Integrated anode structure for passive direct methanol fuel cells with neat methanol operation

Science.gov (United States)

Wu, Huijuan; Zhang, Haifeng; Chen, Peng; Guo, Jing; Yuan, Ting; Zheng, Junwei; Yang, Hui

2014-02-01

A microporous titanium plate based integrated anode structure (Ti-IAS) suitable for passive direct methanol fuel cells (DMFCs) fueled with neat methanol is reported. This anode structure incorporates a porous titanium plate as a methanol mass transfer barrier and current collector, pervaporation film for passively vaporizing methanol, vaporous methanol cavity for evenly distributing fuel, and channels for carbon dioxide venting. With the effective control of methanol delivery rate, the Ti-IAS based DMFC allows the direct use of neat methanol as the fuel source. In the meantime, the required water for methanol-oxidation reaction at the anode can also be fully recovered from the cathode with the help of the highly hydrophobic microporous layer in the cathode. DMFCs incorporating this new anode structure exhibit a power density as high as 40 mW cm-2 and a high volumetric energy density of 489 Wh L-1 operating with neat methanol and at 25 °C. Importantly, no obvious performance degradation of the passive DMFC system is observed after more than 90 h of continuous operation. The experimental results reveal that the compact DMFC based on the Ti-IAS exhibits a substantial potential as power sources for portable applications.

Novel Anode Catalyst for Direct Methanol Fuel Cells

Directory of Open Access Journals (Sweden)

S. Basri

2014-01-01

Full Text Available PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni and iron (Fe. Multiwalled carbon nanotubes (MWCNTs are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX, X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and X-ray photoelectron spectroscopy (XPS, are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR. The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2–5 nm PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g−1 catalyst.

Advances in direct oxidation methanol fuel cells

Science.gov (United States)

Surampudi, S.; Narayanan, S. R.; Vamos, E.; Frank, H.; Halpert, G.; Laconti, Anthony B.; Kosek, J.; Prakash, G. K. Surya; Olah, G. A.

1993-01-01

Fuel cells that can operate directly on fuels such as methanol are attractive for low to medium power applications in view of their low weight and volume relative to other power sources. A liquid feed direct methanol fuel cell has been developed based on a proton exchange membrane electrolyte and Pt/Ru and Pt catalyzed fuel and air/O2 electrodes, respectively. The cell has been shown to deliver significant power outputs at temperatures of 60 to 90 C. The cell voltage is near 0.5 V at 300 mA/cm(exp 2) current density and an operating temperature of 90 C. A deterrent to performance appears to be methanol crossover through the membrane to the oxygen electrode. Further improvements in performance appear possible by minimizing the methanol crossover rate.

Methanol Oxidation on Pt3Sn(111) for Direct Methanol Fuel Cells: Methanol Decomposition.

Science.gov (United States)

Lu, Xiaoqing; Deng, Zhigang; Guo, Chen; Wang, Weili; Wei, Shuxian; Ng, Siu-Pang; Chen, Xiangfeng; Ding, Ning; Guo, Wenyue; Wu, Chi-Man Lawrence

2016-05-18

PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt3Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CHxOHy, x = 1-3, y = 0-1) were strongly adsorbed and preferred decomposition rather than desorption on Pt3Sn(111). The competitive methanol decomposition started with the initial O-H bond scission followed by successive C-H bond scissions, (i.e., CH3OH → CH3O → CH2O → CHO → CO). The Brønsted-Evans-Polanyi relations and energy barrier decomposition analyses identified the C-H and O-H bond scissions as being more competitive than the C-O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt3Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.

Recent Advances in High-Performance Direct Methanol Fuel Cells

Science.gov (United States)

Narayanan, S. R.; Chun, W.; Valdez, T. I.; Jeffries-Nakamura, B.; Frank, H.; Surumpudi, S.; Halpert, G.; Kosek, J.; Cropley, C.; La Conti, A. B.;

Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

Science.gov (United States)

Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

2015-04-18

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

Experimental analysis of methanol cross-over in a direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Casalegno, Andrea [Dipartimento di Energetica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: andrea.casalegno@polimi.it; Grassini, Paolo [Dipartimento di Energetica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: PGrassini@seal.it; Marchesi, Renzo [Dipartimento di Energetica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: renzo.marchesi@polimi.it

2007-03-15

Methanol cross-over through the polymeric membrane is one of the main causes limiting direct methanol fuel cell performances. It causes fuel wasting and enhances cathode overpotential. A repeatable and reproducible measurement system, that assures the traceability of the measurement to international reference standards, is necessary to compare different fuel cell construction materials. In this work a method to evaluate methanol cross-over rate and operating condition influence is presented and qualified in term of measurement uncertainty. In the investigated range, the methanol cross-over rate results mainly due to diffusion through the membrane, in fact it is strongly affected by temperature. Moreover the cross-over influence on fuel utilization and fuel cell efficiency is investigated. The methanol cross-over rate appears linearly proportional to electrochemical fuel utilization and values, obtained by measurements at different anode flow rate but constant electrochemical fuel utilization, are roughly equal; methanol wasting, due to cross-over, is considerable and can still be higher than electrochemical utilization. The fuel recirculation effect on energy efficiency has been investigated and it was found that fuel recirculation gives more advantage at low temperature, but fuel cell energy efficiency results are in any event higher at high temperature.

Experimental analysis of methanol cross-over in a direct methanol fuel cell

International Nuclear Information System (INIS)

Casalegno, Andrea; Grassini, Paolo; Marchesi, Renzo

2007-01-01

Methanol cross-over through the polymeric membrane is one of the main causes limiting direct methanol fuel cell performances. It causes fuel wasting and enhances cathode overpotential. A repeatable and reproducible measurement system, that assures the traceability of the measurement to international reference standards, is necessary to compare different fuel cell construction materials. In this work a method to evaluate methanol cross-over rate and operating condition influence is presented and qualified in term of measurement uncertainty. In the investigated range, the methanol cross-over rate results mainly due to diffusion through the membrane, in fact it is strongly affected by temperature. Moreover the cross-over influence on fuel utilization and fuel cell efficiency is investigated. The methanol cross-over rate appears linearly proportional to electrochemical fuel utilization and values, obtained by measurements at different anode flow rate but constant electrochemical fuel utilization, are roughly equal; methanol wasting, due to cross-over, is considerable and can still be higher than electrochemical utilization. The fuel recirculation effect on energy efficiency has been investigated and it was found that fuel recirculation gives more advantage at low temperature, but fuel cell energy efficiency results are in any event higher at high temperature

Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing

Energy Technology Data Exchange (ETDEWEB)

Fletcher, James H. [University of North Florida; Cox, Philip [University of North Florida; Harrington, William J [University of North Florida; Campbell, Joseph L [University of North Florida

2013-09-03

containment. PROJECT OVERVIEW The University of North Florida (UNF), with project partner the University of Florida, recently completed the Department of Energy (DOE) project entitled “Advanced Direct Methanol Fuel Cell for Mobile Computing”. The primary objective of the project was to advance portable fuel cell system technology towards the commercial targets as laid out in the DOE R&D roadmap by developing a 20-watt, direct methanol fuel cell (DMFC), portable power supply based on the UNF innovative “passive water recovery” MEA. Extensive component, sub-system, and system development and testing was undertaken to meet the rigorous demands of the consumer electronic application. Numerous brassboard (nonpackaged) systems were developed to optimize the integration process and facilitating control algorithm development. The culmination of the development effort was a fully-integrated, DMFC, power supply (referred to as DP4). The project goals were 40 W/kg for specific power, 55 W/l for power density, and 575 Whr/l for energy density. It should be noted that the specific power and power density were for the power section only, and did not include the hybrid battery. The energy density is based on three, 200 ml, fuel cartridges, and also did not include the hybrid battery. The results show that the DP4 system configured without the methanol concentration sensor exceeded all performance goals, achieving 41.5 W/kg for specific power, 55.3 W/l for power density, and 623 Whr/l for energy density. During the project, the DOE revised its technical targets, and the definition of many of these targets, for the portable power application. With this revision, specific power, power density, specific energy (Whr/kg), and energy density are based on the total system, including fuel tank, fuel, and hybridization battery. Fuel capacity is not defined, but the same value is required for all calculations. Test data showed that the DP4 exceeded all 2011 Technical Status values; for example

A selective electrocatalyst-based direct methanol fuel cell operated at high concentrations of methanol.

Science.gov (United States)

Feng, Yan; Liu, Hui; Yang, Jun

2017-06-01

Owing to the serious crossover of methanol from the anode to the cathode through the polymer electrolyte membrane, direct methanol fuel cells (DMFCs) usually use dilute methanol solutions as fuel. However, the use of high-concentration methanol is highly demanded to improve the energy density of a DMFC system. Instead of the conventional strategies (for example, improving the fuel-feed system, membrane development, modification of electrode, and water management), we demonstrate the use of selective electrocatalysts to run a DMFC at high concentrations of methanol. In particular, at an operating temperature of 80°C, the as-fabricated DMFC with core-shell-shell Au@Ag 2 S@Pt nanocomposites at the anode and core-shell Au@Pd nanoparticles at the cathode produces a maximum power density of 89.7 mW cm -2 at a methanol feed concentration of 10 M and maintains good performance at a methanol concentration of up to 15 M. The high selectivity of the electrocatalysts achieved through structural construction accounts for the successful operation of the DMFC at high concentrations of methanol.

A selective electrocatalyst–based direct methanol fuel cell operated at high concentrations of methanol

Science.gov (United States)

Feng, Yan; Liu, Hui; Yang, Jun

2017-01-01

Owing to the serious crossover of methanol from the anode to the cathode through the polymer electrolyte membrane, direct methanol fuel cells (DMFCs) usually use dilute methanol solutions as fuel. However, the use of high-concentration methanol is highly demanded to improve the energy density of a DMFC system. Instead of the conventional strategies (for example, improving the fuel-feed system, membrane development, modification of electrode, and water management), we demonstrate the use of selective electrocatalysts to run a DMFC at high concentrations of methanol. In particular, at an operating temperature of 80°C, the as-fabricated DMFC with core-shell-shell Au@Ag2S@Pt nanocomposites at the anode and core-shell Au@Pd nanoparticles at the cathode produces a maximum power density of 89.7 mW cm−2 at a methanol feed concentration of 10 M and maintains good performance at a methanol concentration of up to 15 M. The high selectivity of the electrocatalysts achieved through structural construction accounts for the successful operation of the DMFC at high concentrations of methanol. PMID:28695199

Development of new membrane materials for direct methanol fuel cells

NARCIS (Netherlands)

Yildirim, M.H.

2009-01-01

Development of new membrane materials for direct methanol fuel cells Direct methanol fuel cells (DMFCs) can convert the chemical energy of a fuel directly into electrical energy with high efficiency and low emission of pollutants. DMFCs can be used as the power sources to portable electronic devices

Studies on Methanol Crossover in Liquid-Feed Direct Methanol Pem Fuel Cells

Science.gov (United States)

Narayanan, S. R.

1995-01-01

The performance of liquid feed direct methanol fuel cells using various types of Nafion membranes as the solid polymer electrolyte have been studied. The rate of fuel crossover and electrical performance has been measured for cells with Nafion membranes of various thicknesses and equivalent weights. The crossover rate is found to decrease with increasing thickness and applied current. The dependence of crossover rate on current density can be understood in terms of a simple linear diffusion model which suggests that the crossover rate can be influenced by the electrode structure in addition to the membrane. The studies suggest that Nafion EW 1500 is a very promising alternate to Nafion EW 1100 for direct methanol fuel cells.

Polypyrrole layered SPEES/TPA proton exchange membrane for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Neelakandan, S.; Kanagaraj, P. [PG & Research Department of Chemistry, Polymeric Materials Research Lab, Alagappa Government Arts College, Karaikudi 630003 (India); Sabarathinam, R.M. [Functional Material Division, Central Electrochemical Research Institute, Karaikudi 630006 (India); Nagendran, A., E-mail: nagimmm@yahoo.com [PG & Research Department of Chemistry, Polymeric Materials Research Lab, Alagappa Government Arts College, Karaikudi 630003 (India)

2015-12-30

Graphical abstract: - Highlights: • A series of Ppy layered SPEES/TPA composite membranes were prepared. • SPEES/TPA-Ppy hybrid membranes displayed efficient methanol resistance than Nafion 117. • SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity of 2.86 × 104 S cm{sup 3} s. • Increasing Ppy layer on membrane surface reduces the leaching out of tungstophosphoric acid. - Abstract: Hybrid membranes based on sulfonated poly(1,4-phenylene ether ether sulfone) (SPEES)/tungstophosphoric acid (TPA) were prepared. SPEES/TPA membrane surfaces were modified with polypyrrole (Ppy) by in situ polymerization method to reduce the TPA leaching. The morphology and electrochemical property of the surface coated membranes were studied by SEM, AFM, water uptake, ion exchange capacity, proton conductivity, methanol permeability and tensile strength. The water uptake and the swelling ratio of the surface coated membranes decreased with increasing the Ppy layer. The surface roughness of the hybrid membrane was decreased with an increase in Ppy layer on the membrane surface. The methanol permeability of SPEES/TPA-Ppy4 hybrid membrane was significantly suppressed and found to be 2.1 × 10{sup −7} cm{sup 2} s{sup −1}, which is 1.9 times lower than pristine SPEES membrane. The SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity (2.86 × 10{sup 4} S cm{sup −3} s) than the other membrane with low TPA leaching. The tensile strength of hybrid membranes was improved with the introduction of Ppy layer. Combining their lower swelling ratio, high thermal stability and selectivity, SPEES/TPA-Ppy4 membranes could be a promising material as PEM for DMFC applications.

Polypyrrole layered SPEES/TPA proton exchange membrane for direct methanol fuel cells

International Nuclear Information System (INIS)

Neelakandan, S.; Kanagaraj, P.; Sabarathinam, R.M.; Nagendran, A.

2015-01-01

Graphical abstract: - Highlights: • A series of Ppy layered SPEES/TPA composite membranes were prepared. • SPEES/TPA-Ppy hybrid membranes displayed efficient methanol resistance than Nafion 117. • SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity of 2.86 × 104 S cm"3 s. • Increasing Ppy layer on membrane surface reduces the leaching out of tungstophosphoric acid. - Abstract: Hybrid membranes based on sulfonated poly(1,4-phenylene ether ether sulfone) (SPEES)/tungstophosphoric acid (TPA) were prepared. SPEES/TPA membrane surfaces were modified with polypyrrole (Ppy) by in situ polymerization method to reduce the TPA leaching. The morphology and electrochemical property of the surface coated membranes were studied by SEM, AFM, water uptake, ion exchange capacity, proton conductivity, methanol permeability and tensile strength. The water uptake and the swelling ratio of the surface coated membranes decreased with increasing the Ppy layer. The surface roughness of the hybrid membrane was decreased with an increase in Ppy layer on the membrane surface. The methanol permeability of SPEES/TPA-Ppy4 hybrid membrane was significantly suppressed and found to be 2.1 × 10"−"7 cm"2 s"−"1, which is 1.9 times lower than pristine SPEES membrane. The SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity (2.86 × 10"4 S cm"−"3 s) than the other membrane with low TPA leaching. The tensile strength of hybrid membranes was improved with the introduction of Ppy layer. Combining their lower swelling ratio, high thermal stability and selectivity, SPEES/TPA-Ppy4 membranes could be a promising material as PEM for DMFC applications.

Selectivity of Direct Methanol Fuel Cell Membranes

Directory of Open Access Journals (Sweden)

Antonino S. Aricò

2015-11-01

Full Text Available Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion® were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK, new generation perfluorosulfonic acid (PFSA systems, and composite zirconium phosphate–PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC. The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA was higher than the benchmark Nafion® 115-based MEA (77 mW·cm−2 vs. 64 mW·cm−2. This result was due to a lower methanol crossover (47 mA·cm−2 equivalent current density for s-PEEK vs. 120 mA·cm−2 for Nafion® 115 at 60 °C as recorded at OCV with 2 M methanol and a suitable area specific resistance (0.15 Ohm cm2 for s-PEEK vs. 0.22 Ohm cm2 for Nafion® 115.

Selectivity of Direct Methanol Fuel Cell Membranes.

Science.gov (United States)

Aricò, Antonino S; Sebastian, David; Schuster, Michael; Bauer, Bernd; D'Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

2015-11-24

Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion(®) were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate-PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion(®) 115-based MEA (77 mW·cm(-2) vs. 64 mW·cm(-2)). This result was due to a lower methanol crossover (47 mA·cm(-2) equivalent current density for s-PEEK vs. 120 mA·cm(-2) for Nafion(®) 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm² for s-PEEK vs. 0.22 Ohm cm² for Nafion(®) 115).

Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells

DEFF Research Database (Denmark)

Olesen, Anders Christian

An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... surpasses batteries in important areas, fundamental research is still required to improve durability and performance. Particularly the transport of methanol and water within the cell structure is difficult to study in-situ. A demand therefore exist for the fundamental development of mathematical models...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...

Sensing methanol concentration in direct methanol fuel cell with total harmonic distortion: Theory and application

International Nuclear Information System (INIS)

Mao Qing; Krewer, Ulrike

2012-01-01

The nonlinear frequency response of a direct methanol fuel cell (DMFC) is studied by analyzing the total harmonic distortion (THD) spectra. The dependence of the THD spectra on methanol concentration and methanol oxidation kinetics is investigated by means of both simulation and experiment. Simulation using a continuous stirred tank reactor network model suggests that the methanol concentration profile in the anode has a strong impact on the THD spectra. The experimentally observed nonlinear behavior of the DMFC anode can be qualitatively reproduced with a model containing a three-step methanol oxidation mechanism with Kauranen–Frumkin/Temkin kinetics. Both experiment and simulation results show that THD value has a monotonic correlation with methanol concentration at certain frequencies and its sensitivity to concentration is improved with increased current amplitude. The monotonic relationship enables the THD to sense the methanol concentration level by the DMFC itself, which is of mayor interest for the portable application as an external sensor for the system can be omitted.

Effect of pervaporation plate thickness on the rate of methanol evaporation in a passive vapor-feed direct methanol fuel cell

Science.gov (United States)

Fauzi, N. F. I.; Hasran, U. A.; Kamarudin, S. K.

2015-09-01

In a passive vapor-feed direct methanol fuel cell (DMFC), methanol vapor is typically obtained using a pervaporation plate in a process by which liquid methanol contained in the fuel reservoir undergoes a phase change to vapor in the anodic vapor chamber. This work investigates the effect of pervaporation plate thickness on the rate of methanol evaporation using a three-dimensional simulation model developed by varying the plate thickness. A. The rate of methanol evaporation was measured using Darcy's law. The rate of methanol evaporation was found to be inversely proportional to the plate thickness, where the decrease in thickness inevitably lowers the resistance along the plate and consequently increases the methanol transport through the plate. This shows that the plate thickness has a significant influence on the rate of methanol evaporation and thereby plays an important role in improving the performance of the passive vapor-feed direct methanol fuel cell.

Solar Hybrid Hydrogen Production in Sunbelt and Shipping to Japan as a Liquid fuel of Methanol

International Nuclear Information System (INIS)

Tamaura, Y.; Hasegawa, N.; Kaneko, H.; Utamura, M.; Katayama, Y.; Onozaki, M.; Hasuike, H.

2006-01-01

Solar hybrid methanol (SH-methanol) production (6000 t/day) from natural gas and coal using H 2 and O 2 gases, which are produced by electrolysis with solar thermal power (Tokyo Tech Beam-down concentration solar power generation with molten salt heat-storage system) at Sunbelt in Australia was studied from the economical view point. This system is the combined system of O 2 -burning coal gasification (C+1/2O 2 =CO), natural gas reforming by O 2 -partial oxidation (CH 4 + 1/2O 2 = CO + 2H 2 ), and water decomposition by electrolysis with solar thermal power (H 2 O = H 2 + 1/2O 2 ). In this production system, the SH-methanol is produced with zero CO 2 emission, shipped to Japan by oil tanker, and can be used as solar hybrid hydrogen in Japan for fuel cell. The solar hybrid methanol production cost of 24 yen/kg (58 US dollars bbl crude oil equivalent, April, 2006) is obtained with the solar power cost of the Tokyo Tech Beam-down solar concentration solar power generation with molten salt heat-storage. This cost is lower than the crude oil (67 US dollars bbl crude oil equivalent, April, 2006) and LPG (72 US dollars/ bbl crude oil equivalent, January, 2006). (authors)

Effect of pervaporation plate thickness on the rate of methanol evaporation in a passive vapor-feed direct methanol fuel cell

International Nuclear Information System (INIS)

Fauzi, N F I; Hasran, U A; Kamarudin, S K

2015-01-01

In a passive vapor-feed direct methanol fuel cell (DMFC), methanol vapor is typically obtained using a pervaporation plate in a process by which liquid methanol contained in the fuel reservoir undergoes a phase change to vapor in the anodic vapor chamber. This work investigates the effect of pervaporation plate thickness on the rate of methanol evaporation using a three-dimensional simulation model developed by varying the plate thickness. A. The rate of methanol evaporation was measured using Darcy's law. The rate of methanol evaporation was found to be inversely proportional to the plate thickness, where the decrease in thickness inevitably lowers the resistance along the plate and consequently increases the methanol transport through the plate. This shows that the plate thickness has a significant influence on the rate of methanol evaporation and thereby plays an important role in improving the performance of the passive vapor-feed direct methanol fuel cell. (paper)

Reactivity descriptors for direct methanol fuel cell anode catalysts

DEFF Research Database (Denmark)

Ferrin, Peter; Nilekar, Anand Udaykumar; Greeley, Jeff

2008-01-01

oxidation to CO2 are investigated: an indirect mechanism that goes through a CO intermediate and a direct mechanism where methanol is oxidized to CO2 without the formation of a CO intermediate. For the direct mechanism, we find that, because of CO poisoning, only a small current will result on all non......We have investigated the anode reaction in direct methanol fuel cells using a database of adsorption free energies for 16 intermediates on 12 close-packed transition metal surfaces calculated with periodic, self-consistent, density functional theory (DFT-GGA). This database, combined with a simple...... electrokinetic model of the methanol electrooxidation reaction, yields mechanistic insights that are consistent with previous experimental and theoretical studies on Pt, and extends these insights to a broad spectrum of other transition metals. In addition, by using linear scaling relations between...

Long Term Performance Study of a Direct Methanol Fuel Cell Fed with Alcohol Blends

OpenAIRE

Teresa J. Leo; Miguel A. Raso; Emilio Navarro; Eleuterio Mora

2013-01-01

The use of alcohol blends in direct alcohol fuel cells may be a more environmentally friendly and less toxic alternative to the use of methanol alone in direct methanol fuel cells. This paper assesses the behaviour of a direct methanol fuel cell fed with aqueous methanol, aqueous ethanol and aqueous methanol/ethanol blends in a long term experimental study followed by modelling of polarization curves. Fuel cell performance is seen to decrease as the ethanol content rises, and subsequent opera...

Modeling and Simulation of the Direct Methanol Fuel Cell

Science.gov (United States)

Wohr, M.; Narayanan, S. R.; Halpert, G.

1996-01-01

From intro.: The direct methanol liquid feed fuel cell uses aqueous solutions of methanol as fuel and oxygen or air as the oxidant and uses an ionically conducting polymer membrane such as Nafion(sup r)117 and the electrolyte. This type of direct oxidation cell is fuel versatile and offers significant advantages in terms of simplicity of design and operation...The present study focuses on the results of a phenomenological model based on current understanding of the various processed operating in these cells.

Performance comparison of two low-CO2 emission solar/methanol hybrid combined cycle power systems

International Nuclear Information System (INIS)

Li, Yuanyuan; Zhang, Na; Lior, Noam

2015-01-01

Highlights: • Two novel solar hybrid combined cycle systems have been proposed and analyzed. • The power systems integrate solar-driven thermo-chemical conversion and CO 2 capture. • Exergy efficiency of about 55% and specific CO 2 emissions of 34 g/kW h are predicted. • Systems CO 2 emissions are 36.8% lower compared to a combined cycle with CO 2 capture. • The fossil fuel demand is ∼30% lower with a solar share of ∼20%. - Abstract: Two novel hybrid combined cycle power systems that use solar heat and methanol, and integrate CO 2 capture, are proposed and analyzed, one based on solar-driven methanol decomposition and the other on solar-driven methanol reforming. The high methanol conversion rates at relatively low temperatures offer the advantage of using the solar heat at only 200–300 °C to drive the syngas production by endothermic methanol conversions and its conversion to chemical energy. Pre-combustion decarbonization is employed to produce CO 2 -free fuel from the fully converted syngas, which is then burned to produce heat at the high temperature for power generation in the proposed advanced combined cycle systems. To improve efficiency, the systems’ configurations were based on the principle of cascade use of multiple heat sources of different temperatures. The thermodynamic performance of the hybrid power systems at its design point is simulated and evaluated. The results show that the hybrid systems can attain an exergy efficiency of about 55%, and specific CO 2 emissions as low as 34 g/kW h. Compared to a gas/steam combined cycle with flue gas CO 2 capture, the proposed solar-assisted system CO 2 emissions are 36.8% lower, and a fossil fuel saving ratio of ∼30% is achievable with a solar thermal share of ∼20%. The system integration predicts high efficiency conversion of solar heat and low-energy-penalty CO 2 capture, with the additional advantage that solar heat is at relatively low temperature where its collection is cheaper and

Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation

Directory of Open Access Journals (Sweden)

Feng Lili

2011-01-01

Full Text Available Abstract In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene were characterized by SEM, TEM, and zeta potential measurements. It is confirmed that the prepared Au@PtAg alloy nanorods/graphene hybrid composites own good catalytic function for methanol electro-oxidation by cyclic voltammograms measurements, and exhibited higher catalytic activity and more stability than pure Au@Pt nanorods and Au@AgPt alloy nanorods. In conclusion, the prepared PtAg alloy nanoislands/graphene hybrid composites own high stability and catalytic activity in methanol electro-oxidation, so that it is one kind of high-performance catalyst, and has great potential in applications such as methanol fuel cells in near future.

Operation characteristic analysis of a direct methanol fuel cell system using the methanol sensor-less control method

Energy Technology Data Exchange (ETDEWEB)

Chen, C.Y.; Chang, C.L. [Institute of Nuclear Energy Research (INER), Longtan Township, Taoyuan County (China); Sung, C.C. [National Taiwan University (China)

2012-10-15

The application of methanol sensor-less control in a direct methanol fuel cell (DMFC) system eliminates most of the problems encountered when using a methanol sensor and is one of the major solutions currently used in commercial DMFCs. This study focuses on analyzing the effect of the operating characteristics of a DMFC system on its performance under the methanol sensor-less control as developed by Institute of Nuclear Energy Research (INER). Notably, the influence of the dispersion of the methanol injected on the behavior of the system is investigated systematically. In addition, the mechanism of the methanol sensor-less control is investigated by varying factors such as the timing of the injection of methanol, the cathode flow rate, and the anode inlet temperature. These results not only provide insight into the mechanism of methanol sensor-less control but can also aid in the improvement and application of DMFC systems in portable and low-power transportation. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The JPL Direct Methanol Liquid-feed PEM Fuel Cell

Science.gov (United States)

Halpert, G.; Surampudi, S.

1994-01-01

Recently, there has been a breakthrough in fuel cell technology in the Energy Storage Systems Group at the Jet Propulsion Laboratory with the develpment of a direct methanol, liquid-feed, solid polymer electrolyte membrane (PEM) fuel cell... The methanol liquid-feed, solid polymer electrolyte (PEM) design has numerous system level advantages over the gas-feed design. These include:...

Long Term Performance Study of a Direct Methanol Fuel Cell Fed with Alcohol Blends

Directory of Open Access Journals (Sweden)

Eleuterio Mora

2013-01-01

Full Text Available The use of alcohol blends in direct alcohol fuel cells may be a more environmentally friendly and less toxic alternative to the use of methanol alone in direct methanol fuel cells. This paper assesses the behaviour of a direct methanol fuel cell fed with aqueous methanol, aqueous ethanol and aqueous methanol/ethanol blends in a long term experimental study followed by modelling of polarization curves. Fuel cell performance is seen to decrease as the ethanol content rises, and subsequent operation with aqueous methanol only partly reverts this loss of performance. It seems that the difference in the oxidation rate of these alcohols may not be the only factor affecting fuel cell performance.

The Direct Methanol Liquid-Feed Fuel Cell

Science.gov (United States)

Halpert, Gerald

1997-01-01

Until the early 1990's the idea of a practical direct methanol fuel cell from transportation and other applications was just that, an idea. Several types of fuel cells that operate under near ambient conditions were under development.

Lightweight Stacks of Direct Methanol Fuel Cells

Science.gov (United States)

Narayanan, Sekharipuram; Valdez, Thomas

2004-01-01

An improved design concept for direct methanol fuel cells makes it possible to construct fuel-cell stacks that can weigh as little as one-third as much as do conventional bipolar fuel-cell stacks of equal power. The structural-support components of the improved cells and stacks can be made of relatively inexpensive plastics. Moreover, in comparison with conventional bipolar fuel-cell stacks, the improved fuel-cell stacks can be assembled, disassembled, and diagnosed for malfunctions more easily. These improvements are expected to bring portable direct methanol fuel cells and stacks closer to commercialization. In a conventional bipolar fuel-cell stack, the cells are interspersed with bipolar plates (also called biplates), which are structural components that serve to interconnect the cells and distribute the reactants (methanol and air). The cells and biplates are sandwiched between metal end plates. Usually, the stack is held together under pressure by tie rods that clamp the end plates. The bipolar stack configuration offers the advantage of very low internal electrical resistance. However, when the power output of a stack is only a few watts, the very low internal resistance of a bipolar stack is not absolutely necessary for keeping the internal power loss acceptably low.

Response of a direct methanol fuel cell to fuel change

Energy Technology Data Exchange (ETDEWEB)

Leo, T.J. [Dpto de Sistemas Oceanicos y Navales- ETSI Navales, Univ. Politecnica de Madrid, Avda Arco de la Victoria s/n, 28040 Madrid (Spain); Raso, M.A.; de la Blanca, E. Sanchez [Dpto de Quimica Fisica I- Fac. CC. Quimicas, Univ. Complutense de Madrid, Avda Complutense s/n, 28040 Madrid (Spain); Navarro, E.; Villanueva, M. [Dpto de Motopropulsion y Termofluidodinamica, ETSI Aeronauticos, Univ. Politecnica de Madrid, Pza Cardenal Cisneros 3, 28040 Madrid (Spain); Moreno, B. [Instituto de Ceramica y Vidrio, Consejo Superior de Investigaciones Cientificas, C/Kelsen 5, Campus de la UAM, 28049 Cantoblanco, Madrid (Spain)

2010-10-15

Methanol and ethanol have recently received much attention as liquid fuels particularly as alternative 'energy-vectors' for the future. In this sense, to find a direct alcohol fuel cell that able to interchange the fuel without losing performances in an appreciable way would represent an evident advantage in the field of portable applications. In this work, the response of a in-house direct methanol fuel cell (DMFC) to the change of fuel from methanol to ethanol and its behaviour at different ambient temperature values have been investigated. A corrosion study on materials suitable to fabricate the bipolar plates has been carried out and either 316- or 2205-duplex stainless steels have proved to be adequate for using in direct alcohol fuel cells. Polarization curves have been measured at different ambient temperature values, controlled by an experimental setup devised for this purpose. Data have been fitted to a model taking into account the temperature effect. For both fuels, methanol and ethanol, a linear dependence of adjustable parameters with temperature is obtained. Fuel cell performance comparison in terms of open circuit voltage, kinetic and resistance is established. (author)

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells.

Science.gov (United States)

Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

2016-08-15

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF-supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells

Directory of Open Access Journals (Sweden)

Jiyoung Kim

2016-08-01

Full Text Available Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC. The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR activities and the electrochemical double layer compared with common carbon black (CB. To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF–supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

Novel Materials for High Efficiency Direct Methanol Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Carson, Stephen [Arkema Inc.; Mountz, David [Arkema Inc.; He, Wensheng [Arkema Inc.; Zhang, Tao [Arkema Inc.

2013-12-31

Direct methanol fuel cell membranes were developed using blends of different polyelectrolytes with PVDF. The membranes showed complex relationships between polyelectrolyte chemistry, morphology, and processing. Although the PVDF grade was found to have little effect on the membrane permselectivity, it does impact membrane conductivity and methanol permeation values. Other factors, such as varying the polyelectrolyte polarity, using varying crosslinking agents, and adjusting the equivalent weight of the membranes impacted methanol permeation, permselectivity, and areal resistance. We now understand, within the scope of the project work completed, how these inter-related performance properties can be tailored to achieve a balance of performance.

Hybrid 3D structures of ZnO nanoflowers and PdO nanoparticles as a highly selective methanol sensor.

Science.gov (United States)

Acharyya, D; Huang, K Y; Chattopadhyay, P P; Ho, M S; Fecht, H-J; Bhattacharyya, P

2016-05-10

The present study concerns the enhancement of methanol selectivity of three dimensional (3D) nanoflowers (NFs) of ZnO by dispersing nickel oxide (NiO) and palladium oxide (PdO) nanoparticles on the surface of the nanoflowers to form localized hybrid nano-junctions. The nanoflowers were fabricated through a liquid phase deposition technique and the modification was achieved by addition of NiCl and PdCl2 solutions. In addition to the detailed structural (like X-ray diffraction (XRD), electron dispersive spectroscopy (EDS), X-ray mapping, XPS) and morphological characterization (by field emission scanning electron microscopy (FESEM)), the existence of different defect states (viz. oxygen vacancy) was also confirmed by photoluminescence (PL) spectroscopy. The sensing properties of the pristine and metal oxide nanoparticle (NiO/PdO)-ZnO NF hybrid sensor structures, towards different alcohol vapors (methanol, ethanol, 2-propanol) were investigated in the concentration range of 0.5-700 ppm at 100-350 °C. Methanol selectivity study against other interfering species, viz. ethanol, 2-propanol, acetone, benzene, xylene and toluene was also investigated. It was found that the PdO-ZnO NF hybrid system offered enhanced selectivity towards methanol at low temperature (150 °C) compared to the NiO-ZnO NF and pristine ZnO NF counterparts. The underlying mechanism for such improvement has been discussed with respective energy band diagram and preferential dissociation of target species on such 3D hybrid structures. The corresponding improvement in transient characteristics has also been co-related with the proposed model.

Effect of sorbed methanol, current, and temperature on multicomponent transport in nafion-based direct methanol fuel cells.

Science.gov (United States)

Rivera, Harry; Lawton, Jamie S; Budil, David E; Smotkin, Eugene S

2008-07-24

The CO2 in the cathode exhaust of a liquid feed direct methanol fuel cell (DMFC) has two sources: methanol diffuses through the membrane electrode assembly (MEA) to the cathode where it is catalytically oxidized to CO2; additionally, a portion of the CO2 produced at the anode diffuses through the MEA to the cathode. The potential-dependent CO2 exhaust from the cathode was monitored by online electrochemical mass spectrometry (ECMS) with air and with H2 at the cathode. The precise determination of the crossover rates of methanol and CO2, enabled by the subtractive normalization of the methanol/air to the methanol/H2 ECMS data, shows that methanol decreases the membrane viscosity and thus increases the diffusion coefficients of sorbed membrane components. The crossover of CO2 initially increases linearly with the Faradaic oxidation of methanol, reaches a temperature-dependent maximum, and then decreases. The membrane viscosity progressively increases as methanol is electrochemically depleted from the anode/electrolyte interface. The crossover maximum occurs when the current dependence of the diffusion coefficients and membrane CO2 solubility dominate over the Faradaic production of CO2. The plasticizing effect of methanol is corroborated by measurements of the rotational diffusion of TEMPONE (2,2,6,6-tetramethyl-4-piperidone N-oxide) spin probe by electron spin resonance spectroscopy. A linear inverse relationship between the methanol crossover rate and current density confirms the absence of methanol electro-osmotic drag at concentrations relevant to operating DMFCs. The purely diffusive transport of methanol is explained in terms of current proton solvation and methanol-water incomplete mixing theories.

Modelling and experimental studies on a direct methanol fuel cell working under low methanol crossover and high methanol concentrations

Energy Technology Data Exchange (ETDEWEB)

Oliveira, V.B.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [Instituto Nacional de Energia e Geologia, Fuel Cells and Hydrogen, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal)

2009-08-15

A number of issues need to be resolved before DMFC can be commercially viable such as the methanol crossover and water crossover which must be minimised in portable DMFCs. The main gain of this work is to systematically vary commercial MEA materials and check their influence on the cell performance of a direct methanol fuel cell operating at close to room temperature. A detailed experimental study on the performance of an <> developed DMFC with 25 cm{sup 2} of active membrane area, working near the ambient conditions is described. Tailored MEAs (membrane-electrode assemblies), with different structures and combinations of gas diffusion layers (GDLs), were designed and tested in order to select optimal working conditions at high methanol concentration levels without sacrificing performance. The experimental polarization and power density curves were successfully compared with the predictions of a steady state, one-dimensional model accounting for coupled heat and mass transfer, along with the electrochemical reactions occurring in the DMFC recently developed by the same authors. The influence of the anode gas diffusion layer media, the membrane thickness and the MEA properties on the cell performance are explained under the light of the predicted methanol crossover rate across the membrane. A tailored MEA build-up with the common available commercial materials was proposed to achieve relatively low methanol crossover, operating at high methanol concentrations. The use of adequate materials for the gas diffusion layers (carbon paper at the anode GDL and carbon cloth at the cathode GDL) enables the use of thinner membranes enhancing the water back diffusion which is essential to work at high methanol concentrations. (author)

Structural Study of Reduced Graphene Oxide/ Polypyrrole Composite as Methanol Sensor in Direct Methanol Fuel Cell

International Nuclear Information System (INIS)

Mumtazah Atiqah Hassan; Siti Kartom Kamarudin; Siti Kartom Kamarudin

2016-01-01

Density functional theory (DFT) computations were performed on the optimized geometric and electronic properties of reduced graphene oxide/polypyrole (rGO/ PPy) composite in comparison with pure graphene and graphene oxide structures. Incorporation of both reduced GO (rGO) and PPy will form a good composite which have advantages from both materials such as good mechanical strength and excellent electrical conductivity. These composite would be very suitable in fabrication of methanol sensor in direct methanol fuel cell (DMFC). The HOMO-LUMO energy (eV) was also calculated. These computations provide a theoretical explanation for the good performance of rGO/ PPy composite as electrode materials in methanol sensor. (author)

A simple preparation of very high methanol tolerant cathode electrocatalyst for direct methanol fuel cell based on polymer-coated carbon nanotube/platinum.

Science.gov (United States)

Yang, Zehui; Nakashima, Naotoshi

2015-07-20

The development of a durable and methanol tolerant electrocatalyst with a high oxygen reduction reaction activity is highly important for the cathode side of direct methanol fuel cells. Here, we describe a simple and novel methodology to fabricate a practically applicable electrocatalyst with a high methanol tolerance based on poly[2,2'-(2,6-pyridine)-5,5'-bibenzimidazole]-wrapped multi-walled carbon nanotubes, on which Pt nanoparticles have been deposited, then coated with poly(vinylphosphonic acid) (PVPA). The polymer coated electrocatalyst showed an ~3.3 times higher oxygen reduction reaction activity compared to that of the commercial CB/Pt and methanol tolerance in the presence of methanol to the electrolyte due to a 50% decreased methanol adsorption on the Pt after coating with the PVPA. Meanwhile, the peroxide generation of the PVPA coated electrocatalyst was as low as 0.8% with 2 M methanol added to the electrolyte, which was much lower than those of the non-PVPA-coated electrocatalyst (7.5%) and conventional CB/Pt (20.5%). Such a high methanol tolerance is very important for the design of a direct methanol fuel cell cathode electrocatalyst with a high performance.

Improved Flow-Field Structures for Direct Methanol Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Gurau, Bogdan [Nuvant Systems Inc., Crown Point, IN (United States)

2013-05-31

The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.

High performance direct methanol fuel cell with thin electrolyte membrane

Science.gov (United States)

Wan, Nianfang

2017-06-01

A high performance direct methanol fuel cell is achieved with thin electrolyte membrane. 320 mW cm-2 of peak power density and over 260 mW cm-2 at 0.4 V are obtained when working at 90 °C with normal pressure air supply. It is revealed that the increased anode half-cell performance with temperature contributes primarily to the enhanced performance at elevated temperature. From the comparison of iR-compensated cathode potential of methanol/air with that of H2/air fuel cell, the impact of methanol crossover on cathode performance decreases with current density and becomes negligible at high current density. Current density is found to influence fuel efficiency and methanol crossover significantly from the measurement of fuel efficiency at different current density. At high current density, high fuel efficiency can be achieved even at high temperature, indicating decreased methanol crossover.

Silicon Based Direct Methanol Fuel Cells

DEFF Research Database (Denmark)

Larsen, Jackie Vincent

The purpose of this project has been to investigate and fabricate small scale Micro Direct Methanol Fuel Cells (μDMFC). They are investigated as a possible alternative for Zinc-air batteries in small size consumer devices such as hearing aids. In such devices the conventional rechargeable batteries...... such as lithium-ion batteries have insufficiently low energy density. Methanol is a promising fuel for such devices due to the high energy density and ease of refueling compared to charging batteries, making μDMFC a suitable replacement energy source. In this Ph.D. dissertation, silicon micro fabrication...... techniques where utilized to build μDMFCs with the purpose of engineering the structures, both on the micro and nano scales in order to realize a high level of control over the membrane and catalyst components. The work presents four different monolithic fuel cell designs. The primary design is based...

Electrochemical characterization of Pt-Ru-Pd catalysts for methanol oxidation reaction in direct methanol fuel cells.

Science.gov (United States)

Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

2011-01-01

PtRuPd nanoparticles on carbon black were prepared and characterized as electrocatalysts for methanol oxidation reaction in direct methanol fuel cells. Nano-sized Pd (2-4 nm) particles were deposited on Pt/C and PtRu/C (commercial products) by a simple chemical reduction process. The structural and physical information of the PtRuPd/C were confirmed by TEM and XRD, and their electrocatalytic activities were measured by cyclic voltammetry and linear sweep voltammetry. The catalysts containing Pd showed higher electrocatalytic activity for methanol oxidation reaction than the other catalysts. This might be attributed to an increase in the electrochemical surface area of Pt, which is caused by the addition of Pd; this results in increased catalyst utilization.

Recent progresses in materials for the direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Lamy, C; Leger, J M [Centre National de la Recherche Scientifique (CNRS), 86 - Poitiers (France)

1998-12-31

Research programs are being conducted worldwide to develop a clean, zero emissions electric vehicle. However, even with the most advanced batteries, such as nickel/metal hydride, or lithium ion batteries, the driving range is limited and the recharging time is long. Only fuel cells which can convert chemical energy directly into electrical energy can compete with internal combustion engines. This paper reviewed the recent progress made in the development of a direct methanol fuel cell using the concept developed for the proton exchange membrane fuel cell (PEMFC). It was noted that the electrode materials, at the methanol anode and oxygen cathode need to be improved by using multifunctional electrocatalysts. The development of new temperature resistant proton exchange membranes with good ionic conductivity and low methanol cross-over, which resulted from the need to increase operating temperatures above 100 degrees C was also reviewed. 35 refs., 1 tab., 2 figs.

Small-sized and contacting Pt-WC nanostructures on graphene as highly efficient anode catalysts for direct methanol fuel cells.

Science.gov (United States)

Wang, Ruihong; Xie, Ying; Shi, Keying; Wang, Jianqiang; Tian, Chungui; Shen, Peikang; Fu, Honggang

2012-06-11

The synergistic effect between Pt and WC is beneficial for methanol electro-oxidation, and makes Pt-WC catalyst a promising anode candidate for the direct methanol fuel cell. This paper reports on the design and synthesis of small-sized and contacting Pt-WC nanostructures on graphene that bring the synergistic effect into full play. Firstly, DFT calculations show the existence of a strong covalent interaction between WC and graphene, which suggests great potential for anchoring WC on graphene with formation of small-sized, well-dispersed WC particles. The calculations also reveal that, when Pt attaches to the pre-existing WC/graphene hybrid, Pt particles preferentially grow on WC rather than graphene. Our experiments confirmed that highly disperse WC nanoparticles (ca. 5 nm) can indeed be anchored on graphene. Also, Pt particles 2-3 nm in size are well dispersed on WC/graphene hybrid and preferentially grow on WC grains, forming contacting Pt-WC nanostructures. These results are consistent with the theoretical findings. X-ray absorption fine structure spectroscopy further confirms the intimate contact between Pt and WC, and demonstrates that the presence of WC can facilitate the crystallinity of Pt particles. This new Pt-WC/graphene catalyst exhibits a high catalytic efficiency toward methanol oxidation, with a mass activity 1.98 and 4.52 times those of commercial PtRu/C and Pt/C catalysts, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance of PEM Liquid-Feed Direct Methanol-Air Fuel Cells

Science.gov (United States)

Narayanan, S. R.

1995-01-01

A direct methanol-air fuel cell operating at near atmospheric pressure, low-flow rate air, and at temperatures close to 60oC would tremendously enlarge the scope of potential applications. While earlier studies have reported performance with oxygen, the present study focuses on characterizing the performance of a PEM liquid feed direct methanol-air cell consisting of components developed in house. These cells employ Pt-Ru catalyst in the anode, Pt at the cathode and Nafion 117 as the PEM. The effect of pressure, flow rate of air and temperature on cell performance has been studied. With air, the performance level is as high as 0.437 V at 300 mA/cm2 (90oC, 20 psig, and excess air flow) has been attained. Even more significant is the performance level at 60oC, 1 atm and low flow rates of air (3-5 times stoichiometric), which is 0.4 V at 150 mA/cm2. Individual electrode potentials for the methanol and air electrode have been separated and analyzed. Fuel crossover rates and the impact of fuel crossover on the performance of the air electrode have also been measured. The study identifies issues specific to the methanol-air fuel cell and provides a basis for improvement strategies.

Survey report for fiscal 1998. Achievement report on research and development of direct methanol fuel cell; 1998 nendo direct methanol nenryo denchi no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-12-01

Research and development has been performed on a direct methanol fuel cell (DMFC) to generate electric power through direct chemical reaction of methanol not being given modification as a fuel cell to be used for automotive engines. This paper summarizes the achievements in fiscal 1998. In the research of the membranes to conduct ions for the DMFC, an ion conduction membrane which introduces POSS group as the methanol eliminating functional group was prepared to achieve enhancement in tensile strength, heat resistance, and ion conductivity. In the power generation characteristics of the DMFC, verification was given on power generation performance with as high main power density as 0.1 W/cm{sup 2} by using the available electrolytic membranes and electrode catalysts. The characteristics showed effectiveness of the DMFC as the electric power supply source. In addition, fundamental findings were obtained on factors affecting the power generation characteristics of the DMFC as a result of generating power under different conditions. Research and development was given also on the water-methanol-ion exchange polymeric membrane, ion exchange membranes provided with lipophilic and water repellent electrolyte, solid polymeric membranes having high proton conductivity and low methanol permeability, and a new micro-porous filling type polymeric membrane. (NEDO)

Development and characterisation of a portable direct methanol fuel cell stack

Energy Technology Data Exchange (ETDEWEB)

Oedegaard, A.

2005-11-21

This thesis deals with the development and characterisation of a portable direct methanol fuel cell stack. In addition, calculations of the transport of methanol and water in the membrane are compared with experimentally determined values. It also includes investigations of the behaviour of single-cells and some of its components, as the anode gas diffusion layer and the anode flow-field. For the addition of methanol to the anode feed loop, a passive concept based on a permeable tube was developed and verified by both experiments and simulations. (orig.)

A Nafion-Ceria Composite Membrane Electrolyte for Reduced Methanol Crossover in Direct Methanol Fuel Cells

Directory of Open Access Journals (Sweden)

Parthiban Velayutham

2017-02-01

Full Text Available An alternative Nafion composite membrane was prepared by incorporating various loadings of CeO2 nanoparticles into the Nafion matrix and evaluated its potential application in direct methanol fuel cells (DMFCs. The effects of CeO2 in the Nafion matrix were systematically studied in terms of surface morphology, thermal and mechanical stability, proton conductivity and methanol permeability. The composite membrane with optimum filler content (1 wt. % CeO2 exhibits a proton conductivity of 176 mS·cm−1 at 70 °C, which is about 30% higher than that of the unmodified membrane. Moreover, all the composite membranes possess a much lower methanol crossover compared to pristine Nafion membrane. In a single cell DMFC test, MEA fabricated with the optimized composite membrane delivered a peak power density of 120 mW·cm−2 at 70 °C, which is about two times higher in comparison with the pristine Nafion membrane under identical operating conditions.

A novel method of methanol concentration control through feedback of the amplitudes of output voltage fluctuations for direct methanol fuel cells

International Nuclear Information System (INIS)

An, Myung-Gi; Mehmood, Asad; Hwang, Jinyeon; Ha, Heung Yong

2016-01-01

This study proposes a novel method for controlling the methanol concentration without using methanol sensors for DMFC (direct methanol fuel cell) systems that have a recycling methanol-feed loop. This method utilizes the amplitudes of output voltage fluctuations of DMFC as a feedback parameter to control the methanol concentration. The relationship between the methanol concentrations and the amplitudes of output voltage fluctuations is correlated under various operating conditions and, based on the experimental correlations, an algorithm to control the methanol concentration with no sensor is established. Feasibility tests of the algorithm have been conducted under various operating conditions including varying ambient temperature with a 200 W-class DMFC system. It is demonstrated that the sensor-less controller is able to control the methanol-feed concentration precisely and to run the DMFC systems more energy-efficiently as compared with other control systems. - Highlights: • A new sensor-less algorithm is proposed to control the methanol concentration without using a sensor. • The algorithm utilizes the voltage fluctuations of DMFC as a feedback parameter to control the methanol feed concentration. • A 200 W DMFC system is operated to evaluate the validity of the sensor-less algorithm. • The algorithm successfully controls the methanol feed concentration within a small error bound.

Low-Pt-Content Anode Catalyst for Direct Methanol Fuel Cells

Science.gov (United States)

Narayanan, Sekharipuram; Whitacre, Jay

2008-01-01

Combinatorial experiments have led to the discovery that a nanophase alloy of Pt, Ru, Ni, and Zr is effective as an anode catalyst material for direct methanol fuel cells. This discovery has practical significance in that the electronic current densities achievable by use of this alloy are comparable or larger than those obtained by use of prior Pt/Ru catalyst alloys containing greater amounts of Pt. Heretofore, the high cost of Pt has impeded the commercialization of direct methanol fuel cells. By making it possible to obtain a given level of performance at reduced Pt content (and, hence, lower cost), the discovery may lead to reduction of the economic impediment to commercialization.

Optimisation of polypyrrole/Nafion composite membranes for direct methanol fuel cells

International Nuclear Information System (INIS)

Zhu Jun; Sattler, Rita R.; Garsuch, Arnd; Yepez, Omar; Pickup, Peter G.

2006-01-01

Acidic and neutral Nafion[reg] 115 perfluorosulphonate membranes have been modified by in situ polymerization of pyrrole using Fe(III) and H 2 O 2 as oxidizing agents, in order to decrease methanol crossover in direct methanol fuel cells. Improved selectivities for proton over methanol transport and improved fuel cell performances were only obtained with membranes that were modified while in the acid form. Use of Fe(III) as the oxidizing agent can produce a large decrease in methanol crossover, but causes polypyrrole deposition on the surface of the membrane. This increases the resistance of the membrane, and leads to poor fuel cell performances due to poor bonding with the electrodes. Surface polypyrrole deposition can be minimized, and surface polypyrrole can be removed, by using H 2 O 2 . The use of Nafion in its tetrabutylammonium form leads to very low methanol permeabilities, and appears to offer potential for manipulating the location of polypyrrole within the Nafion structure

A gradient activation method for direct methanol fuel cells

International Nuclear Information System (INIS)

Liu, Guicheng; Yang, Zhaoyi; Halim, Martin; Li, Xinyang; Wang, Manxiang; Kim, Ji Young; Mei, Qiwen; Wang, Xindong; Lee, Joong Kee

2017-01-01

Highlights: • A gradient activation method was reported firstly for direct methanol fuel cells. • The activity recovery of Pt-based catalyst was introduced into the novel activation process. • The new activation method led to prominent enhancement of DMFC performance. • DMFC performance was improved with the novel activation step by step within 7.5 h. - Abstract: To realize gradient activation effect and recover catalytic activity of catalyst in a short time, a gradient activation method has firstly been proposed for enhancing discharge performance and perfecting activation mechanism of the direct methanol fuel cell (DMFC). This method includes four steps, i.e. proton activation, activity recovery activation, H_2-O_2 mode activation and forced discharging activation. The results prove that the proposed method has gradually realized replenishment of water and protons, recovery of catalytic activity of catalyst, establishment of transfer channels for electrons, protons, and oxygen, and optimization of anode catalyst layer for methanol transfer in turn. Along with the novel activation process going on, the DMFC discharge performance has been improved, step by step, to more than 1.9 times higher than that of the original one within 7.5 h. This method provides a practicable activation way for the real application of single DMFCs and stacks.

Matlab Source Code for Species Transport through Nafion Membranes in Direct Ethanol, Direct Methanol, and Direct Glucose Fuel Cells

OpenAIRE

JH, Summerfield; MW, Manley

2016-01-01

A simple simulation of chemical species movement is presented. The species traverse a Nafion membrane in a fuel cell. Three cells are examined: direct methanol, direct ethanol, and direct glucose. The species are tracked using excess proton concentration, electric field strength, and voltage. The Matlab computer code is provided.

High-Performance Direct Methanol Fuel Cells with Precious-Metal-Free Cathode.

Science.gov (United States)

Li, Qing; Wang, Tanyuan; Havas, Dana; Zhang, Hanguang; Xu, Ping; Han, Jiantao; Cho, Jaephil; Wu, Gang

2016-11-01

Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt-based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol-tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)-based Fe-N-C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe-N-rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe-N-rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe-N-rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.

Emerging methanol-tolerant AlN nanowire oxygen reduction electrocatalyst for alkaline direct methanol fuel cell.

Science.gov (United States)

Lei, M; Wang, J; Li, J R; Wang, Y G; Tang, H L; Wang, W J

2014-08-11

Replacing precious and nondurable Pt catalysts with cheap materials is a key issue for commercialization of fuel cells. In the case of oxygen reduction reaction (ORR) catalysts for direct methanol fuel cell (DMFC), the methanol tolerance is also an important concern. Here, we develop AlN nanowires with diameters of about 100-150 nm and the length up to 1 mm through crystal growth method. We find it is electrochemically stable in methanol-contained alkaline electrolyte. This novel material exhibits pronounced electrocatalytic activity with exchange current density of about 6.52 × 10(-8) A/cm(2). The single cell assembled with AlN nanowire cathodic electrode achieves a power density of 18.9 mW cm(-2). After being maintained at 100 mA cm(-2) for 48 h, the AlN nanowire-based single cell keeps 92.1% of the initial performance, which is in comparison with 54.5% for that assembled with Pt/C cathode. This discovery reveals a new type of metal nitride ORR catalyst that can be cheaply produced from crystal growth method.

Novel crosslinked membranes based on sulfonated poly(ether ether ketone) for direct methanol fuel cells.

Science.gov (United States)

Zhu, Yuanqin; Zieren, Shelley; Manthiram, Arumugam

2011-07-14

Novel covalently crosslinked membranes based on sulfonated poly(ether ether ketone) and carboxylated polysulfone exhibit much lower methanol crossover and better performance in direct methanol fuel cells at 65 °C in 1 and 2 M methanol solutions compared to Nafion 115 membranes.

The Pore Structure of Direct Methanol Fuel Cell Electrodes

DEFF Research Database (Denmark)

Lund, Peter Brilner

2005-01-01

The pore structure and morphology of direct methanol fuel cell electrodes are characterized using mercury intrusion porosimetry and scanning electron microscopy. It is found that the pore size distributions of printed primer and catalyst layers are largely dictated by the powders used to make...

Nafion®/H-ZSM-5 composite membranes with superior performance for direct methanol fuel cells

NARCIS (Netherlands)

Yildirim, M.H.; Curos, Anna Roca; Motuzas, Julius; Motuzas, J.; Julbe, Anne; Stamatialis, Dimitrios; Wessling, Matthias

2009-01-01

Solution cast composite direct methanol fuel cell membranes (DEZ) based on DE2020 Nafion® dispersion and in-house prepared H-ZSM-5 zeolites with different Si/Al ratios were prepared and thoroughly characterized for direct methanol fuel cell (DMFC) applications. All composite membranes have indeed

Methanol electro-oxidation and direct methanol fuel cell using Pt/Rh and Pt/Ru/Rh alloy catalysts

International Nuclear Information System (INIS)

Choi, Jong-Ho; Park, Kyung-Won; Park, In-Su; Nam, Woo-Hyun; Sung, Yung-Eun

2004-01-01

Pt-based binary or ternary catalysts containing Rh for use as anodes in direct methanol fuel cells (DMFC) were synthesized by borohydride reduction method combined with freeze-drying. The resulting catalysts had a specific surface area of approximately 65-75 m 2 /g. X-ray diffraction (XRD) patterns indicated that the catalysts were well alloyed and the average size of alloy catalysts was confirmed by transmission electron microscopy (TEM). The Pt/Rh (2:1) and Pt/Ru/Rh (5:4:1) alloy catalysts showed better catalytic activities for methanol electro-oxidation than Pt or Pt/Ru (1:1), respectively

Direct observation of deformation of nafion surfaces induced by methanol treatment by using atomic force microscopy

International Nuclear Information System (INIS)

Umemura, Kazuo; Kuroda, Reiko; Gao Yanfeng; Nagai, Masayuki; Maeda, Yuta

2008-01-01

We successfully characterized the effect of methanol treatment on the nanoscopic structures of a nafion film, which is widely used in direct methanol fuel cells (DMFCs). Atomic force microscopy (AFM) was used to repetitively image a particular region of a nafion sample before and after methanol solutions were dropped onto the nafion film and dried in air. When the surface was treated with 20% methanol for 5 min, many nanopores appeared on the surface. The number of nanopores increased when the sample was treated twice or thrice. By repetitive AFM imaging of a particular region of the same sample, we found that the shapes of the nanopores were deformed by the repeated methanol treatment, although the size of the nanopores had not significantly changed. The creation of the nanopores was affected by the concentration of methanol. Our results directly visualized the effects of methanol treatment on the surface structures of a nafion film at nanoscale levels for the first time

Performance of direct methanol fuel cell with a palladium–silica nanofibre/Nafion composite membrane

International Nuclear Information System (INIS)

Thiam, H.S.; Daud, W.R.W.; Kamarudin, S.K.; Mohamad, A.B.; Kadhum, A.A.H.; Loh, K.S.; Majlan, E.H.

2013-01-01

Highlights: • This study introduces Pd–SiO 2 Carbon Nano Fibre as an additive to Nafion membrane. • It investigates the effects of membrane annealing temperature and casting solvent. • Results show that Pd–SiO 2 fibre/Nafion performs lower methanol permeability. • This could effectively reduces methanol crossover in direct methanol fuel cell. - Abstract: Palladium–silica nanofibres (Pd–SiO 2 fibre) were adopted as an additive to Nafion recast membranes in order to reduce methanol crossover and improve the cell performance. The performance of a membrane electrode assembly (MEA) with fabricated composite membrane was evaluated through a passive air-breathing single cell direct methanol fuel cell (DMFC). The limiting crossover current density was measured to determine the methanol permeation in the DMFC. The effects of membrane annealing temperature and casting solvent of composite membrane on the cell performance were investigated and are discussed here. Compared to recast Nafion with the same thickness (150 μm), the Pd–SiO 2 fibre/Nafion composite membrane exhibited higher performance and lower methanol permeability. A maximum power density of 10.4 mW cm −2 was obtained with a 2 M methanol feed, outperforming the much thicker commercial Nafion 117 with a power density of 7.95 mW cm −2 under the same operating conditions. The experimental results showed that the Pd–SiO 2 fibre as inorganic fillers for Nafion could effectively reduce methanol crossover and improve the membrane performance in DMFC applications

Characterization of an anionic-exchange membranes for direct methanol alkaline fuel cells

Energy Technology Data Exchange (ETDEWEB)

Abuin, Graciela C. [Centro de Procesos Superficiales, Instituto Nacional de Tecnologia Industrial (INTI), Av. Gral. Paz 5445, B1650KNA, San Martin, Buenos Aires (Argentina); Nonjola, Patrick; Mathe, Mkhulu K. [Council for Scientific and Industrial Research (CSIR), Material Science and Manufacturing, PO Box 395, Brumeria, Pretoria 0001 (South Africa); Franceschini, Esteban A.; Izraelevitch, Federico H.; Corti, Horacio R. [Departamento de Fisica de la Materia Condensada, Comision Nacional de Energia Atomica (CNEA), Av. Gral. Paz 1499, B1650KNA, San Martin, Buenos Aires (Argentina)

2010-06-15

Ammonium quaternized polymers such as poly (arylene ether sulfones) are being developed and studied as candidates of ionomeric materials for application in alkaline fuel cells, due to their low cost and promising electrochemical properties. In this work, a quaternary ammonium polymer was synthesized by chloromethylation of a commercial polysulfone followed by amination process. Quaternized polysulfone membrane properties such us water and water-methanol uptake, electrical conductivity and Young's modulus were evaluated and compared to Nafion 117, commonly employed in direct methanol fuel cells. The anionic polysulfone membrane sorbs more water than Nafion all over the whole range of water activities, but it uptakes much less methanol as compared to Nafion. The specific conductivity of the fully hydrated polysulfone membrane equilibrated with KOH solutions at ambient temperature increases with the KOH concentration, reaching a maximum of 0.083 S cm{sup -1} for 2 M KOH, slightly less conductive than Nafion 117. The elastic modulus of the polysulfone membranes inmersed in water is similar to that reported for Nafion membranes under the same conditions. We concluded that quaternized polysulfone membrane are good candidates as electrolytes in alkaline direct methanol fuel cells. (author)

Update on status of direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Reeve, R.W.

2002-07-01

This report reviews the progress in direct methanol fuel cell (DMFC) technology since 1995 and examines the opportunities for this technology in various market sectors. The report is divided into two parts. Part A describes the state-of-the-art of DMFC technology, developments in electrocatalysis relevant to DMFCs, single cell and stack performance, and polymer electrolyte membranes. Part B discusses the viability of current DMFCs for portable and automotive applications, and examines some niche markets, eg for remote power applications. Market opportunities, technical issues, applications and competing technologies are summarised. The report draws attention to the outstanding technical issues and recommends further development in a number of areas (eg inexpensive membranes with lower rates of methanol crossover, membranes with lower rates of water permeation, improved power density and methods to ensure solutions do not freeze in cold climates).

A small mono-polar direct methanol fuel cell stack with passive operation

Science.gov (United States)

Chan, Y. H.; Zhao, T. S.; Chen, R.; Xu, C.

A passive direct methanol fuel cell (DMFC) stack that consists of six unit cells was designed, fabricated, and tested. The stack was tested with different methanol concentrations under ambient conditions. It was found that the stack performance increased when the methanol concentration inside the fuel tank was increased from 2.0 to 6.0 M. The improved performance is primarily due to the increased cell temperature as a result of the exothermic reaction between the permeated methanol and oxygen on the cathode. Moreover, the increased cell temperature enhanced the water evaporation rate on the air-breathing cathode, which significantly reduced water flooding on the cathode and further improved the stack performance. This passive DMFC stack, providing 350 mW at 1.8 V, was successfully applied to power a seagull display kit. The seagull display kit can continuously run for about 4 h on a single charge of 25 cm 3 4.0-M methanol solution.

Characterization of polymer blends PES/SPSf and PES/SPEEK for direct methanol fuel cells

NARCIS (Netherlands)

Manea, G.C.; Mulder, M.H.V.

2002-01-01

Existing polymer electrolyte membranes (PEMs) applied for hydrogen fuel cells are frequently not suitable for direct methanol fuel cells due to the high methanol permeability. Therefore, new materials are required and in order to avoid laborious fuel cell experiments with a so-called

Improved Direct Methanol Fuel Cell Stack

Science.gov (United States)

Wilson, Mahlon S.; Ramsey, John C.

2005-03-08

A stack of direct methanol fuel cells exhibiting a circular footprint. A cathode and anode manifold, tie-bolt penetrations and tie-bolts are located within the circular footprint. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet and outlet cathode manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold, where the serpentine channels of the anode are orthogonal to the serpentine channels of the cathode. Located between the two plates is the fuel cell active region.

High Performance and Cost-Effective Direct Methanol Fuel Cells: Fe-N-C Methanol-Tolerant Oxygen Reduction Reaction Catalysts.

Science.gov (United States)

Sebastián, David; Serov, Alexey; Artyushkova, Kateryna; Gordon, Jonathan; Atanassov, Plamen; Aricò, Antonino S; Baglio, Vincenzo

2016-08-09

Direct methanol fuel cells (DMFCs) offer great advantages for the supply of power with high efficiency and large energy density. The search for a cost-effective, active, stable and methanol-tolerant catalyst for the oxygen reduction reaction (ORR) is still a great challenge. In this work, platinum group metal-free (PGM-free) catalysts based on Fe-N-C are investigated in acidic medium. Post-treatment of the catalyst improves the ORR activity compared with previously published PGM-free formulations and shows an excellent tolerance to the presence of methanol. The feasibility for application in DMFC under a wide range of operating conditions is demonstrated, with a maximum power density of approximately 50 mW cm(-2) and a negligible methanol crossover effect on the performance. A review of the most recent PGM-free cathode formulations for DMFC indicates that this formulation leads to the highest performance at a low membrane-electrode assembly (MEA) cost. Moreover, a 100 h durability test in DMFC shows suitable applicability, with a similar performance-time behavior compared to common MEAs based on Pt cathodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reduction of methanol crossover by thin cracked metal barriers at the interface between membrane and electrode in direct methanol fuel cells

Science.gov (United States)

Kim, Sungjun; Jang, Segeun; Kim, Sang Moon; Ahn, Chi-Yeong; Hwang, Wonchan; Cho, Yong-Hun; Sung, Yung-Eun; Choi, Mansoo

2017-09-01

This work reports the successful reduction in methanol crossover by creating a thin cracked metal barrier at the interface between a Nafion® membrane and an electrode in direct methanol fuel cells (DMFCs). The cracks are generated by simple mechanical stretching of a metal deposited Nafion® membrane as a result of the elastic mismatch between the two attached surfaces. The cracked metal barriers with varying strains (∼0.5 and ∼1.0) are investigated and successfully incorporated into the DMFC. Remarkably, the membrane electrode assembly with the thin metal crack exhibits comparable ohmic resistance as well as reduction of methanol crossover, which enhanced the device performance.

Three-dimensional anode engineering for the direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Bauer, A.; Oloman, C.W.; Gyenge, E.L. [Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC (Canada)

2009-09-05

Catalyzed graphite felt three-dimensional anodes were investigated in direct methanol fuel cells (DMFCs) operated with sulfuric acid supporting electrolyte. With a conventional serpentine channel flow field the preferred anode thickness was 100 {mu}m, while a novel flow-by anode showed the best performance with a thickness of 200-300 {mu}m. The effects of altering the methanol concentration, anolyte flow rate and operating temperature on the fuel cell superficial power density were studied by full (2{sup 3} + 1) factorial experiments on a cell with anode area of 5 cm{sup 2} and excess oxidant O{sub 2} at 200 kPa(abs). For operation in the flow-by mode with 2 M methanol at 2 cm{sup 3} min{sup -1} and 353 K the peak power density was 2380 W m{sup -2} with a PtRuMo anode catalyst, while a PtRu catalyst yielded 2240 W m{sup -2} under the same conditions. (author)

Three-dimensional anode engineering for the direct methanol fuel cell

Science.gov (United States)

Bauer, A.; Oloman, C. W.; Gyenge, E. L.

Catalyzed graphite felt three-dimensional anodes were investigated in direct methanol fuel cells (DMFCs) operated with sulfuric acid supporting electrolyte. With a conventional serpentine channel flow field the preferred anode thickness was 100 μm, while a novel flow-by anode showed the best performance with a thickness of 200-300 μm. The effects of altering the methanol concentration, anolyte flow rate and operating temperature on the fuel cell superficial power density were studied by full (2 3 + 1) factorial experiments on a cell with anode area of 5 cm 2 and excess oxidant O 2 at 200 kPa(abs). For operation in the flow-by mode with 2 M methanol at 2 cm 3 min -1 and 353 K the peak power density was 2380 W m -2 with a PtRuMo anode catalyst, while a PtRu catalyst yielded 2240 W m -2 under the same conditions.

On the actual cathode mixed potential in direct methanol fuel cells

Science.gov (United States)

Zago, M.; Bisello, A.; Baricci, A.; Rabissi, C.; Brightman, E.; Hinds, G.; Casalegno, A.

2016-09-01

Methanol crossover is one of the most critical issues hindering commercialization of direct methanol fuel cells since it leads to waste of fuel and significantly affects cathode potential, forming a so-called mixed potential. Unfortunately, due to the sluggish anode kinetics, it is not possible to obtain a reliable estimation of cathode potential by simply measuring the cell voltage. In this work we address this limitation, quantifying the mixed potential by means of innovative open circuit voltage (OCV) tests with a methanol-hydrogen mixture fed to the anode. Over a wide range of operating conditions, the resulting cathode overpotential is between 250 and 430 mV and is strongly influenced by methanol crossover. We show using combined experimental and modelling analysis of cathode impedance that the methanol oxidation at the cathode mainly follows an electrochemical pathway. Finally, reference electrode measurements at both cathode inlet and outlet provide a local measurement of cathode potential, confirming the reliability of the innovative OCV tests and permitting the evaluation of cathode potential up to typical operating current. At 0.25 A cm-2 the operating cathode potential is around 0.85 V and the Ohmic drop through the catalyst layer is almost 50 mV, which is comparable to that in the membrane.

On direct and indirect methanol fuel cells for transportation applications

Energy Technology Data Exchange (ETDEWEB)

Gottesfield, S.

1996-04-01

Research on direct oxidation methanol fuel cells (DMFCs) and polymer electrolyte fuel cells (PEFCs) is discussed. Systems considered for transportation applications are addressed. The use of platinum/ruthenium anode electrocatalysts and platinum cathode electrocatalysts in polymer electrolyte DMFCs has resulted in significant performance enhancements.

Methanol electro-oxidation on platinum modified tungsten carbides in direct methanol fuel cells: a DFT study.

Science.gov (United States)

Sheng, Tian; Lin, Xiao; Chen, Zhao-Yang; Hu, P; Sun, Shi-Gang; Chu, You-Qun; Ma, Chun-An; Lin, Wen-Feng

2015-10-14

In exploration of low-cost electrocatalysts for direct methanol fuel cells (DMFCs), Pt modified tungsten carbide (WC) materials are found to be great potential candidates for decreasing Pt usage whilst exhibiting satisfactory reactivity. In this work, the mechanisms, onset potentials and activity for electrooxidation of methanol were studied on a series of Pt-modified WC catalysts where the bare W-terminated WC(0001) substrate was employed. In the surface energy calculations of a series of Pt-modified WC models, we found that the feasible structures are mono- and bi-layer Pt-modified WCs. The tri-layer Pt-modified WC model is not thermodynamically stable where the top layer Pt atoms tend to accumulate and form particles or clusters rather than being dispersed as a layer. We further calculated the mechanisms of methanol oxidation on the feasible models via methanol dehydrogenation to CO involving C-H and O-H bonds dissociating subsequently, and further CO oxidation with the C-O bond association. The onset potentials for the oxidation reactions over the Pt-modified WC catalysts were determined thermodynamically by water dissociation to surface OH* species. The activities of these Pt-modified WC catalysts were estimated from the calculated kinetic data. It has been found that the bi-layer Pt-modified WC catalysts may provide a good reactivity and an onset oxidation potential comparable to pure Pt and serve as promising electrocatalysts for DMFCs with a significant decrease in Pt usage.

Recast Nafion{sup R}-based membranes for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Dimitrova, Penka; Friedrich, Kaspar A.; Stimming, Ulrich; Vogt, Brunhilde [Department of Physics, Technische Universitaet Muenchen, D-80333 Munich (Germany)

2001-07-01

Commercially available Nafion{sup R} membranes at present do not meet the requirements for direct methanol fuel cell (DMFC) applications, amongst others factors because of their high methanol permeability. With the aim of improving this undesirable characteristic, a modification procedure has been applied to recast Nafion-based membranes. Membranes, containing different additives, are assessed with regard to their conductivity and methanol permeation rate. The preparation of the samples involves the introduction of a small amount of a high boiling point solvent to the as-received Nafion solution and then shaping the membranes by a recasting procedure (drying at room temperature and heating up to 150{sup o}C). An enhancement of the conductivity of the thermally treated membranes in comparison to the commercial Nafion 117 is found. The thickness-normalised methanol permeation rate of the samples, containing inorganic additives (Aerosil and molybdophosphoric acid) decreases compared to the pure recast and as-received Nafion membranes. The observed results are discussed in terms of the membrane structure and preparation. (author)

Facile approach to prepare Pt decorated SWNT/graphene hybrid catalytic ink

Energy Technology Data Exchange (ETDEWEB)

Mayavan, Sundar, E-mail: sundarmayavan@cecri.res.in [Centre for Innovation in Energy Research, CSIR–Central Electrochemical Research Institute, Karaikudi 630006, Tamil Nadu (India); Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 (Korea, Republic of); Mandalam, Aditya; Balasubramanian, M. [Centre for Innovation in Energy Research, CSIR–Central Electrochemical Research Institute, Karaikudi 630006, Tamil Nadu (India); Sim, Jun-Bo [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 (Korea, Republic of); Choi, Sung-Min, E-mail: sungmin@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 (Korea, Republic of)

2015-07-15

Highlights: • Pt NPs were in situ synthesized onto CNT–graphene support in aqueous solution. • The as-prepared material was used directly as a catalyst ink without further treatment. • Catalyst ink is active toward methanol oxidation. • This approach realizes both scalable and greener production of hybrid catalysts. - Abstract: Platinum nanoparticles were in situ synthesized onto hybrid support involving graphene and single walled carbon nanotube in aqueous solution. We investigate the reduction of graphene oxide, and platinum nanoparticle functionalization on hybrid support by X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The as-prepared platinum on hybrid support was used directly as a catalyst ink without further treatment and is active toward methanol oxidation. This work realizes both scalable and greener production of highly efficient hybrid catalysts, and would be valuable for practical applications of graphene based fuel cell catalysts.

Relating Direct Methanol Fuel Cell Performance to Measurements in a Liquid Half Cell

DEFF Research Database (Denmark)

Pedersen, Christoffer Mølleskov; Tynelius, Oskar; Lund-Olesen, Torsten

2015-01-01

Direct methanol fuel cells (DMFC) could act as a replacement for batteries in low power electronics. For instance, micro—DMFC’s could be used to power hearing instruments[1]. The power output of a DMFC is limited by the sluggish kinetics of both the methanol oxidation reaction (MOR) on the anode ...... Cells Bull. 2012 (2012) 12–16. doi:10.1016/S1464-2859(12)70367-X....

Experimental investigation two phase flow in direct methanol fuel cells

International Nuclear Information System (INIS)

Mat, M. D.; Kaplan, Y.; Celik, S.; Oeztural, A.

2007-01-01

Direct methanol fuel cells (DMFC) have received many attentions specifically for portable electronic applications since it utilize methanol which is in liquid form in atmospheric condition and high energy density of the methanol. Thus it eliminates the storage problem of hydrogen. It also eliminates humidification requirement of polymeric membrane which is a problem in PEM fuel cells. Some electronic companies introduced DMFC prototypes for portable electronic applications. Presence of carbon dioxide gases due to electrochemical reactions in anode makes the problem a two phase problem. A two phase flow may occur at cathode specifically at high current densities due to the excess water. Presence of gas phase in anode region and liquid phase in cathode region prevents diffusion of fuel and oxygen to the reaction sites thus reduces the performance of the system. Uncontrolled pressure buildup in anode region increases methanol crossover through membrane and adversely effect the performance. Two phase flow in both anode and cathode region is very effective in the performance of DMYC system and a detailed understanding of two phase flow for high performance DMFC systems. Although there are many theoretical and experimental studies available on the DMFC systems in the literature, only few studies consider problem as a two-phase flow problem. In this study, an experimental set up is developed and species distributions on system are measured with a gas chromatograph. System performance characteristics (V-I curves) is measured depending on the process parameters (temperature, fuel ad oxidant flow rates, methanol concentration etc)

Direct synthesis of dimethyl carbonate from CO2 and methanol over ...

Indian Academy of Sciences (India)

The direct synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO2) and methanol is ... Zirconia and ceria-based catalysts were most effective ... construction of a validation plant for dialkyl carbonates .... (mmol of MeOH consumed/2).

Selective electrocatalysts toward a prototype of the membraneless direct methanol fuel cell.

Science.gov (United States)

Feng, Yan; Yang, Jinhua; Liu, Hui; Ye, Feng; Yang, Jun

2014-01-22

Mastery over the structure of nanomaterials enables control of their properties to enhance their performance for a given application. Herein we demonstrate the design and fabrication of Pt-based nanomaterials with enhanced catalytic activity and superior selectivity toward the reactions in direct methanol fuel cells (DMFCs) upon the deep understanding of the mechanisms of these electrochemical reactions. In particular, the ternary Au@Ag2S-Pt nanocomposites display superior methanol oxidation reaction (MOR) selectivity due to the electronic coupling effect among different domains of the nanocomposites, while the cage-bell structured Pt-Ru nanoparticles exhibit excellent methanol tolerance for oxygen reduction reaction (ORR) at the cathode because of the differential diffusion of methanol and oxygen in the porous Ru shell of the cage-bell nanoparticles. The good catalytic selectivity of these Pt-based nanomaterials via structural construction enables a DMFC to be built without a proton exchange membrane between the fuel electrode and the oxygen electrode.

Direct synthesis of few-layer graphene supported platinum nanocatalyst for methanol oxidation

Science.gov (United States)

Tan, Hong; Ma, Xiaohui; Sheng, Leimei; An, Kang; Yu, Liming; Zhao, Hongbin; Xu, Jiaqiang; Ren, Wei; Zhao, Xinluo

2014-11-01

High-crystalline few-layer graphene supported Pt nanoparticles have been synthesized by arc discharge evaporation of carbon electrodes containing Pt element. A high-temperature treatment under hydrogen atmosphere has been carried out to obtain a new type of Pt/graphene catalyst for methanol oxidation in direct methanol fuel cell. The morphology and structure characterizations of as-grown few-layer graphene supported Pt nanoparticles and Pt/graphene catalysts have been studied by Raman spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy. Cyclic voltammograms and chronoamperometric curves show that our present Pt/graphene catalysts have larger current density for methanol oxidation, higher tolerance to carbon monoxide poisoning, and better stability during the operating procedure, compared to commercial Pt/C catalysts.

Metal membrane-type 25-kW methanol fuel processor for fuel-cell hybrid vehicle

Science.gov (United States)

Han, Jaesung; Lee, Seok-Min; Chang, Hyuksang

A 25-kW on-board methanol fuel processor has been developed. It consists of a methanol steam reformer, which converts methanol to hydrogen-rich gas mixture, and two metal membrane modules, which clean-up the gas mixture to high-purity hydrogen. It produces hydrogen at rates up to 25 N m 3/h and the purity of the product hydrogen is over 99.9995% with a CO content of less than 1 ppm. In this fuel processor, the operating condition of the reformer and the metal membrane modules is nearly the same, so that operation is simple and the overall system construction is compact by eliminating the extensive temperature control of the intermediate gas streams. The recovery of hydrogen in the metal membrane units is maintained at 70-75% by the control of the pressure in the system, and the remaining 25-30% hydrogen is recycled to a catalytic combustion zone to supply heat for the methanol steam-reforming reaction. The thermal efficiency of the fuel processor is about 75% and the inlet air pressure is as low as 4 psi. The fuel processor is currently being integrated with 25-kW polymer electrolyte membrane fuel-cell (PEMFC) stack developed by the Hyundai Motor Company. The stack exhibits the same performance as those with pure hydrogen, which proves that the maximum power output as well as the minimum stack degradation is possible with this fuel processor. This fuel-cell 'engine' is to be installed in a hybrid passenger vehicle for road testing.

New Catalysts for Direct Methanol Oxidation Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Adzic, Radoslav

1998-08-01

A new class of efficient electrocatalytic materials based on platinum - metal oxide systems has been synthetized and characterized by several techniques. Best activity was found with NiWO{sub 4}-, CoWO{sub 4}-, and RuO{sub 2}- sr¡pported platinum catalysts. A very similar activity at room temperature was observed with the electrodes prepared with the catalyst obtained from International Fuel Cells Inc. for the same Pt loading. Surprisingly, the two tungstates per se show a small activity for methanol oxidation without any Pt loading. Synthesis of NiWO{sub 4} and CoWO{sub 4} were carried out by solid-state reactions. FTIR spectroscopy shows that the tungstates contain a certain amount of physically adsorbed water even after heating samples at 200{degrees}C. A direct relationship between the activity for methanol oxidation and the amount of adsorbed water on those oxides has been found. The Ru(0001) single crystal shows a very small activity for CO adsorption and oxidation, in contrast to the behavior of polycrystalline Ru. In situ extended x-ray absorption fine structure spectroscopy (EXAFS) and x-ray absorption near edge spectroscopy (XANES) showed that the OH adsorption on Ru in the Pt-Ru alloy appears to be the limiting step in methanol oxidation. This does not occur for Pt-RuO{SUB 2} electrocatalyst, which explains its advantages over the Pt-Ru alloys. The IFCC electrocatalyst has the properties of the Pt-Ru alloy.

Biodiesel synthesis by direct transesterification of microalga Botryococcus braunii with continuous methanol reflux.

Science.gov (United States)

Hidalgo, Pamela; Ciudad, Gustavo; Schober, Sigurd; Mittelbach, Martin; Navia, Rodrigo

2015-04-01

Direct transesterification of Botryococcus braunii with continuous acyl acceptor reflux was evaluated. This method combines in one step lipid extraction and esterification/transesterification. Fatty acid methyl esters (FAME) synthesis by direct conversion of microalgal biomass was carried out using sulfuric acid as catalyst and methanol as acyl acceptor. In this system, once lipids are extracted, they are contacted with the catalyst and methanol reaching 82%wt of FAME yield. To optimize the reaction conditions, a factorial design using surface response methodology was applied. The effects of catalyst concentration and co-solvent concentration were studied. Hexane was used as co-solvent for increasing lipid extraction performance. The incorporation of hexane in the reaction provoked an increase in FAME yield from 82% (pure methanol) to 95% when a 47%v/v of hexane was incorporated in the reaction. However, the selectivity towards non-saponifiable lipids such as sterols was increased, negatively affecting biodiesel quality. Copyright © 2015 Elsevier Ltd. All rights reserved.

Direct methanol feed fuel cell with reduced catalyst loading

Science.gov (United States)

Kindler, Andrew (Inventor)

1999-01-01

Improvements to direct feed methanol fuel cells include new protocols for component formation. Catalyst-water repellent material is applied in formation of electrodes and sintered before application of ionomer. A membrane used in formation of an electrode assembly is specially pre-treated to improve bonding between catalyst and membrane. The improved electrode and the pre-treated membrane are assembled into a membrane electrode assembly.

Review on utilization of the pervaporation membrane for passive vapor feed direct methanol fuel cell

International Nuclear Information System (INIS)

Fauzi, N F I; Hasran, U A; Kamarudin, S K

2013-01-01

The Direct Methanol Fuel Cell (DMFC) is a promising portable power source for mobile electronic devices because of its advantages including easy fuel storage, high energy density, low temperature operation and compact structure. In DMFC, methanol is used as a fuel source where it can be fed in liquid or vapor phase. However, the vapor feed DMFC has an advantage over the liquid feed system as it has the potential to have a higher operating temperature to increase the reaction rates and power outputs, to enhance the mass transfers, to reduce methanol crossover, reliable for high methanol concentration and it can increase the fuel cell performance. Methanol vapor can be delivered to the anode by using a pervaporation membrane, heating the liquid methanol or another method that compatible. Therefore, this paper is a review on vapor feed DMFC as a better energy source than liquid feed DMFC, the pervaporation membrane used to vaporize methanol feed from the reservoir and its applications in vapor feed DMFC

New ETFE-based membrane for direct methanol fuel cell

International Nuclear Information System (INIS)

Saarinen, V.; Kallio, T.; Paronen, M.; Tikkanen, P.; Rauhala, E.; Kontturi, K.

2005-01-01

The investigated membranes are based on 35-bar μ m thick commercial poly(ethylene-alt-tetrafluoroethylene) (ETFE) films. The films were made proton conductive by means of irradiation treatment followed by sulfonation. These membranes have exceptionally low water uptake and excellent dimensional stability. The new membranes are investigated widely in a laboratory-scale direct methanol fuel cell (DMFC). The temperature range used in the fuel cell tests was 30-85-bar o C and the measurement results were compared to those of the Nafion ( R)115 membrane. Also methanol permeability through the ETFE-based membrane was measured as a function of temperature, resulting in values less than 10% of the corresponding values for Nafion ( R)115, which was considerably thicker than the experimental membrane. Methanol crossover was reported to decrease when the thickness of the membrane increases, so the ETFE-based membrane compares favourably to Nafion ( R) membranes. The maximum power densities achieved with the experimental ETFE-based membrane were about 40-65% lower than the corresponding values of the Nafion ( R)115 membrane, because of the lower conductivity and noticeably higher IR-losses. Chemical and mechanical stability of the ETFE-based membrane appeared to be promising since it was tested over 2000-bar h in the DMFC without any performance loss

Micro-patterned Nafion membranes for direct methanol fuel cell applications

NARCIS (Netherlands)

Yildirim, M.H.; te Braake, J.; Aran, H.C.; Stamatialis, Dimitrios; Wessling, Matthias

2010-01-01

In this work, we report the direct methanol fuel cell (DMFC) performance of micro-patterned (μp) Nafion® 117 (N117) membranes prepared by hot embossing and compare them with that of normal N117 and heat and pressure treated (hp) N117 non-patterned (smooth) membranes. Our results suggest that the

Bifunctional anode catalysts for direct methanol fuel cells

DEFF Research Database (Denmark)

Rossmeisl, Jan; Ferrin, Peter; Tritsaris, Georgios

2012-01-01

Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties......: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro-oxidation....... Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts....

Characteristics of PVdF copolymer/Nafion blend membrane for direct methanol fuel cell (DMFC)

International Nuclear Information System (INIS)

Cho, Ki-Yun; Eom, Ji-Yong; Jung, Ho-Young; Choi, Nam-Soon; Lee, Yong Min; Park, Jung-Ki; Choi, Jong-Ho; Park, Kyung-Won; Sung, Yung-Eun

2004-01-01

For direct methanol fuel cell, blends of vinylidene fluoride-hexafluoropropylene copolymer (P(VdF-co-HFP)) and Nafion were prepared the different equivalent weight of Nafion. The investigations of the blend morphology were performed by means of permeability test, uptake measurement, differential-scanning calorimetry (DSC), and scanning electron microscopy. In the blend membranes, many pores were created as the content of Nafion in blend increased. Then, the methanol uptake was sharply increased. But the methanol permeability was not sharply increased because the methanol permeation through blend membranes is diffusion-controlled process. The methanol permeability of N10 (low equivalent weight) series was similar to that of N11 series (high equivalent weight). The proton conductivity of N10 series was around one and a half times higher than that of N11 series. The cell performance of the blend was much enhanced when the equivalent weight of Nafion was 1000

Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Sherazi, Tauqir A. [Department of Chemistry, Government College University, Lahore 54000 (Pakistan); Institute for Chemical Process and Environmental Technology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Guiver, Michael D.; Kingston, David; Xue, Xinzhong [Institute for Chemical Process and Environmental Technology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Ahmad, Shujaat [PIEAS/PINSTECH, P O Nilore, Islamabad 45650 (Pakistan); Kashmiri, M. Akram [Department of Chemistry, Government College University, Lahore 54000 (Pakistan); Board of Intermediate and Secondary Education, Lahore 54000 (Pakistan)

2010-01-01

Styrene was grafted onto ultrahigh molecular weight polyethylene powder (UHMWPE) by gamma irradiation using a {sup 60}Co source. Compression moulded films of selected pre-irradiated styrene-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PS) were post-sulfonated to the sulfonic acid derivative (UHMWPE-g-PSSA) for use as proton exchange membranes (PEMs). The sulfonation was confirmed by X-ray photoelectron spectroscopy (XPS). The melting and flow properties of UHMWPE and UHMWPE-g-PS are conducive to forming homogeneous pore-free membranes. Both the ion conductivity and methanol permeability coefficient increased with degree of grafting, but the grafted membranes showed comparable or higher ion conductivity and lower methanol permeability than Nafion {sup registered} 117 membrane. One UHMWPE-g-PS membrane was fabricated into a membrane-electrode assembly (MEA) and tested as a single cell direct methanol fuel cell (DMFC). Low membrane cost and acceptable fuel cell performance indicate that UHMWPE-g-PSSA membranes could offer an alternative approach to perfluorosulfonic acid-type membranes for DMFC. (author)

Design of an optimal micro direct methanol fuel cell for portable applications

International Nuclear Information System (INIS)

Ahmad, M.M.; Kamarudin, S.K.; Daud, W.R.W

2010-01-01

The main constraint for the commercialization of micro Direct Methanol Fuel cell (μDMFC) for small power generation is the performance of the fuel cell. In this study, a high-power μDMFC with a power output of 14.10 mW on an active area of 4 cm 2 and catalyst loading of 0.5 mg cm -2 cathode was successfully developed. The optimal parameters for methanol concentration and catalyst loading were determined. Besides that, testing of performance, long term and open circuit voltage (OCV) was also performed. (author)

Co-catalytic effect of Ni in the methanol electro-oxidation on Pt-Ru/C catalyst for direct methanol fuel cell

International Nuclear Information System (INIS)

Wang, Z.B.; Yin, G.P.; Zhang, J.; Sun, Y.C.; Shi, P.F.

2006-01-01

This research is aimed to improve the utilization and activity of anodic catalysts, thus to lower the contents of noble metals loading in anodes for methanol electro-oxidation. The direct methanol fuel cell anodic catalysts, Pt-Ru-Ni/C and Pt-Ru/C, were prepared by chemical reduction method. Their performances were tested by using a glassy carbon working electrode through cyclic voltammetric curves, chronoamperometric curves and half-cell measurement in a solution of 0.5 mol/L CH 3 OH and 0.5 mol/L H 2 SO 4 . The composition of the Pt-Ru-Ni and Pt-Ru surface particles were determined by EDAX analysis. The particle size and lattice parameter of the catalysts were determined by means of X-ray diffraction (XRD). XRD analysis showed that both of the catalysts exhibited face-centered cubic structures and had smaller lattice parameters than Pt-alone catalyst. Their sizes are small, about 4.5 nm. No significant differences in the methanol electro-oxidation on both electrodes were found by using cyclic voltammetry, especially regarding the onset potential for methanol electro-oxidation. The electrochemically active-specific areas of the Pt-Ru-Ni/C and Pt-Ru/C catalysts are almost the same. But, the catalytic activity of the Pt-Ru-Ni/C catalyst is higher for methanol electro-oxidation than that of the Pt-Ru/C catalyst. Its tolerance performance to CO formed as one of the intermediates of methanol electro-oxidation is better than that of the Pt-Ru/C catalyst

Characterisation of micro direct methanol fuel cells with silicon plate supported integrated ionomer membranes

DEFF Research Database (Denmark)

Larsen, Jackie Vincent; Dalslet, Bjarke Thomas; Kallesee, C.

2013-01-01

This work deals with the investigation and fabrication of Micro Direct Methanol Fuel Cells (μDMFC). They are investigated as a possible alternative for zinc-air batteries in small size consumer devices such as hearing aids. In such devices the conventional rechargeable batteries such as lithium......-ion batteries have insufficiently low energy density in the range 240 Wh/L to 300 Wh/L Methanol is a promising fuel for such devices due to the high energy density, with pure methanol having an energy density of 4400 Wh/L. Using a liquid fuel also allows refueling, which can be achieved much faster than battery...

Mixed phase Pt-Ru catalyst for direct methanol fuel cell anode by flame aerosol synthesis

DEFF Research Database (Denmark)

Chakraborty, Debasish; Bischoff, H.; Chorkendorff, Ib

2005-01-01

A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst wa......Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy. (c) 2005 The Electrochemical Society.......A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst...... was found to be a mixture of nanocrystalline, mostly unalloyed Pt and an amorphous phase mostly of Ru and to a lesser extent of Pt oxides on top of the crystalline phase. The flame-produced Pt1Ru1 demonstrated similar onset potential but similar to 60% higher activity compared to commercially available Pt1...

Sensor-less control of the methanol concentration of direct methanol fuel cells at varying ambient temperatures

International Nuclear Information System (INIS)

An, Myung-Gi; Mehmood, Asad; Ha, Heung Yong

2014-01-01

Highlights: • A new algorithm is proposed for the sensor-less control of methanol concentration. • Two different strategies are used depending on the ambient temperatures. • Energy efficiency of the DMFC system has been improved by using the new algorithm. - Abstract: A new version of an algorithm is used to control the methanol concentration in the feed of DMFC systems without using methanol sensors under varying ambient temperatures. The methanol concentration is controlled indirectly by controlling the temperature of the DMFC stack, which correlates well with the methanol concentration. Depending on the ambient temperature relative to a preset reference temperature, two different strategies are used to control the stack temperature: either reducing the cooling rate of the methanol solution passing through an anode-side heat exchanger; or, lowering the pumping rate of the pure methanol to the depleted feed solution. The feasibility of the algorithm is evaluated using a DMFC system that consists of a 200 W stack and the balance of plant (BOP). The DMFC system includes a sensor-less methanol controller that is operated using a LabView system as the central processing unit. The algorithm is experimentally confirmed to precisely control the methanol concentration and the stack temperature at target values under an environment of varying ambient temperatures

Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design.

Science.gov (United States)

Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

2015-11-18

Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells.

Development of a Crosslinked Pore-filling Membrane with an Extremely Low Swelling Ratio and Methanol Crossover for Direct Methanol Fuel Cells

International Nuclear Information System (INIS)

Li, Yunxi; Hoorfar, Mina; Shen, Kuizhi; Fang, Jiyong; Yue, Xigui; Jiang, Zhenhua

2017-01-01

A poly (ether sulphone)-based pore-filling membrane was successfully fabricated and tested against a conventional Nafion-based membrane in direct methanol fuel cells. An amino-containing polymer with a low degree of sulphonation (DS) was synthesized and used as the supporting substrate. The porous substrate was prepared by introducing the porogenic agent (tetrafluoroborate) into the membrane casting solution. The effects of the content of the porogenic agent on the pore morphologies were evaluated using field emission scanning electron microscopy. Then, an epoxy resin was introduced into the porous electrolyte for the first time to minimize the swelling and methanol crossover that resulted from the high degree of sulphonation. In essence, solidification of the amino groups in the substrate results in 3D crosslinking of epoxy resins, which greatly suppresses the swelling and methanol crossover of the composite membranes with enhanced mechanical properties and enhances the thermal and oxidation stability compared to Nafion 117. The resulting composite membrane also shows high proton conductivity that is only slightly lower than that of Nafion 117. However, the selectivity between the proton conductivity and methanol permeability is higher for the composite membranes than that of Nafion 117. The composite membrane also shows a better performance in single cell tests with 10 M methanol.

Improved Anode for a Direct Methanol Fuel Cell

Science.gov (United States)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the

Novel fluoropolymer anion exchange membranes for alkaline direct methanol fuel cells.

Science.gov (United States)

Zhang, Yanmei; Fang, Jun; Wu, Yongbin; Xu, Hankun; Chi, Xianjun; Li, Wei; Yang, Yixu; Yan, Ge; Zhuang, Yongze

2012-09-01

A series of novel fluoropolymer anion exchange membranes based on the copolymer of vinylbenzyl chloride, butyl methacrylate, and hexafluorobutyl methacrylate has been prepared. Fourier transform infrared (FT-IR) spectroscopy and elemental analysis techniques are used to study the chemical structure and chemical composition of the membranes. The water uptake, ion-exchange capacity (IEC), conductivity, methanol permeability, and chemical stability of the membranes are also determined. The membranes exhibit high anionic conductivity in deionized water at 65 °C ranging from 3.86×10(-2) S cm(-1) to 4.36×10(-2) S cm(-1). The methanol permeability coefficients of the membranes are in the range of 4.21-5.80×10(-8) cm(2) s(-1) at 65 °C. The novel membranes also show good chemical and thermal stability. An open-circuit voltage of 0.7 V and a maximum power density of 53.2 mW cm(-2) of alkaline direct methanol fuel cell (ADMFC) with the membrane C, 1 M methanol, 1 M NaOH, and humidified oxygen are achieved at 65 °C. Therefore, these membranes have great potential for applications in fuel cell systems. Copyright © 2012 Elsevier Inc. All rights reserved.

New polymeric electrolyte membranes based on proton donor proton acceptor properties for direct methanol fuel cells

NARCIS (Netherlands)

Manea, G.C.; Mulder, M.H.V.

2002-01-01

In order to reduce the high methanol permeability of membranes in a direct methanol fuel cell application new and better materials are still required. In this paper membranes made from polybenzimidazole/sulfonated polysulfone are given and compared with homopolymer membranes made from sulfonated

Passive direct methanol fuel cells for portable electronic devices

International Nuclear Information System (INIS)

Achmad, F.; Kamarudin, S.K.; Daud, W.R.W.; Majlan, E.H.

2011-01-01

Due to the increasing demand for electricity, clean, renewable energy resources must be developed. Thus, the objective of the present study was to develop a passive direct methanol fuel cell (DMFC) for portable electronic devices. The power output of six dual DMFCs connected in series with an active area of 4 cm 2 was approximately 600 mW, and the power density of the DMFCs was 25 mW cm -2 . The DMFCs were evaluated as a power source for mobile phone chargers and media players. The results indicated that the open circuit voltage of the DMFC was between 6.0 V and 6.5 V, and the voltage under operating conditions was 4.0 V. The fuel cell was tested on a variety of cell phone chargers, media players and PDAs. The cost of energy consumption by the proposed DMFC was estimated to be USD 20 W -1 , and the cost of methanol is USD 4 kW h. Alternatively, the local conventional electricity tariff is USD 2 kW h. However, for the large-scale production of electronic devices, the cost of methanol will be significantly lower. Moreover, the electricity tariff is expected to increase due to the constraints of fossil fuel resources and pollution. As a result, DMFCs will become competitive with conventional power sources.

Effects of dimethyl ether on the performance characteristics of a direct methanol fuel cell

International Nuclear Information System (INIS)

Seo, Sang Hern; Lee, Chang Sik

2013-01-01

Highlights: • Activation loss is significantly reduced in fuel cell with DME-methanol. • DME crossover through the membrane reduces. • The open circuit voltage of DME-methanol the fuel cell increases. • The overall efficiency of the mixed fuel cell is higher than that of DMFC. - Abstract: The objective of this study was to determine the effects of dimethyl ether (DME) on the performance characteristics of a direct methanol fuel cell. Impedance and crossover experiments were performed in order to investigate the performance losses such as ohmic loss, activation loss and crossover loss accurately. The DME was pressurized to 5 bar to supply with liquid phase was and blended with an aqueous methanol solution. In this experiment, the membrane electrode assembly (MEA) was composed of Nafion 115, anode catalyst loaded Pt–Ru and cathode catalyst loaded Pt-Black. Experimental results showed that fuel cells with DME-methanol enhanced performance when compared to fuel cells with methanol only. Such performance enhancement was due to a decrease in activation losses by DME oxidation reactions. As the DME crossover through the membrane was reduced, the open circuit voltage (OCV) of the fuel cell increased. Other output characteristics are also discussed

A high selectivity quaternized polysulfone membrane for alkaline direct methanol fuel cells

CSIR Research Space (South Africa)

Abuin, GC

2015-04-01

Full Text Available polysulfone membrane for alkaline direct methanol fuel cells Graciela C. Abuina, Esteban A. Franceschinib, Patrick Nonjolac, Mkhulu K. Mathec, Mmalewane Modibedic, Horacio R. Cortib,* aCentro de Procesos Superficiales, Instituto Nacional de Tecnología...

Ruthenium–Platinum Catalysts and Direct Methanol Fuel Cells (DMFC: A Review of Theoretical and Experimental Breakthroughs

Directory of Open Access Journals (Sweden)

Ana S. Moura

2017-02-01

Full Text Available The increasing miniaturization of devices creates the need for adequate power sources and direct methanol fuel cells (DMFC are a strong option in the various possibilities under current development. DMFC catalysts are mostly based on platinum, for its outperformance in three key areas (activity, selectivity and stability within methanol oxidation framework. However, platinum poisoning with products of methanol oxidation led to the use of alloys. Ruthenium–platinum alloys are preferred catalysts active phases for methanol oxidation from an industrial point of view and, indeed, ruthenium itself is a viable catalyst for this reaction. In addition, the route of methanol decomposition is crucial in the goal of producing H2 from water reaction with methanol. However, the reaction pathway remains elusive and new approaches, namely in computational methods, have been ensued to determine it. This article reviews the various recent theoretical approaches for determining the pathway of methanol decomposition, and systematizes their validation with experimental data, within methodological context.

Modeling of a 5-cell direct methanol fuel cell using adaptive-network-based fuzzy inference systems

Science.gov (United States)

Wang, Rongrong; Qi, Liang; Xie, Xiaofeng; Ding, Qingqing; Li, Chunwen; Ma, ChenChi M.

The methanol concentrations, temperature and current were considered as inputs, the cell voltage was taken as output, and the performance of a direct methanol fuel cell (DMFC) was modeled by adaptive-network-based fuzzy inference systems (ANFIS). The artificial neural network (ANN) and polynomial-based models were selected to be compared with the ANFIS in respect of quality and accuracy. Based on the ANFIS model obtained, the characteristics of the DMFC were studied. The results show that temperature and methanol concentration greatly affect the performance of the DMFC. Within a restricted current range, the methanol concentration does not greatly affect the stack voltage. In order to obtain higher fuel utilization efficiency, the methanol concentrations and temperatures should be adjusted according to the load on the system.

Modeling of a 5-cell direct methanol fuel cell using adaptive-network-based fuzzy inference systems

Energy Technology Data Exchange (ETDEWEB)

Wang, Rongrong; Li, Chunwen [Department of Automation, Tsinghua University, Beijing 100084 (China); Qi, Liang; Xie, Xiaofeng [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Ding, Qingqing [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Ma, ChenChi M. [National Tsing Hua University, Hsinchu 300 (China)

2008-12-01

The methanol concentrations, temperature and current were considered as inputs, the cell voltage was taken as output, and the performance of a direct methanol fuel cell (DMFC) was modeled by adaptive-network-based fuzzy inference systems (ANFIS). The artificial neural network (ANN) and polynomial-based models were selected to be compared with the ANFIS in respect of quality and accuracy. Based on the ANFIS model obtained, the characteristics of the DMFC were studied. The results show that temperature and methanol concentration greatly affect the performance of the DMFC. Within a restricted current range, the methanol concentration does not greatly affect the stack voltage. In order to obtain higher fuel utilization efficiency, the methanol concentrations and temperatures should be adjusted according to the load on the system. (author)

Modeling of the anode side of a direct methanol fuel cell with analytical solutions

International Nuclear Information System (INIS)

Mosquera, Martin A.; Lizcano-Valbuena, William H.

2009-01-01

In this work, analytical solutions were derived (for any methanol oxidation reaction order) for the profiles of methanol concentration and proton current density, by assuming diffusion mass transport mechanism, Tafel kinetics, and fast proton transport in the anodic catalyst layer of a direct methanol fuel cell. An expression for the Thiele modulus that allows to express the anodic overpotential as a function of the cell current and kinetic and mass transfer parameters was obtained. For high cell current densities, it was found that the Thiele modulus (φ 2 ) varies quadratically with cell current density; yielding a simple correlation between anodic overpotential and cell current density. Analytical solutions were derived for the profiles of both local methanol concentration in the catalyst layer and local anodic current density in the catalyst layer. Under the assumptions of the model presented here, in general, the local methanol concentration in the catalyst layer cannot be expressed as an explicit function of the position in the layer. In spite of this, the equations presented here for the anodic overpotential allow the derivation of new semi-empirical equations

Carbon-Supported Pd and PdFe Alloy Catalysts for Direct Methanol Fuel Cell Cathodes

Directory of Open Access Journals (Sweden)

Luis M. Rivera Gavidia

2017-05-01

Full Text Available Direct methanol fuel cells (DMFCs are electrochemical devices that efficiently produce electricity and are characterized by a large flexibility for portable applications and high energy density. Methanol crossover is one of the main obstacles for DMFC commercialization, forcing the search for highly electro-active and methanol tolerant cathodes. In the present work, carbon-supported Pd and PdFe catalysts were synthesized using a sodium borohydride reduction method and physico-chemically characterized using transmission electron microscopy (TEM and X-ray techniques such as photoelectron spectroscopy (XPS, diffraction (XRD and energy dispersive spectroscopy (EDX. The catalysts were investigated as DMFC cathodes operating at different methanol concentrations (up to 10 M and temperatures (60 °C and 90 °C. The cell based on PdFe/C cathode presented the best performance, achieving a maximum power density of 37.5 mW·cm−2 at 90 °C with 10 M methanol, higher than supported Pd and Pt commercial catalysts, demonstrating that Fe addition yields structural changes to Pd crystal lattice that reduce the crossover effects in DMFC operation.

Effect of operating conditions on energy efficiency for a small passive direct methanol fuel cell

International Nuclear Information System (INIS)

Chu Deryn; Jiang Rongzhong

2006-01-01

Energy conversion efficiency was studied in a direct methanol fuel cell (DMFC) with an air-breathing cathode using Nafion 117 as electrolyte membrane. The effect of operating conditions, such as methanol concentration, discharge voltage and temperature, on Faradic and energy conversion efficiencies was analyzed under constant voltage discharge with quantitative amount of fuel. Both of Faradic and energy conversion efficiencies decrease significantly with increasing methanol concentration and environmental temperature. The Faradic conversion efficiency can be as high as 94.8%, and the energy conversion efficiency can be as high as 23.9% if the environmental temperature is low enough (10 deg. C) under constant voltage discharge at 0.6 V with 3 M methanol for a DMFC bi-cell. Although higher temperature and higher methanol concentration can achieve higher discharge power, it will result in considerable losses of Faradic and energy conversion efficiencies for using Nafion electrolyte membrane. Development of alternative highly conductive membranes with significantly lower methanol crossover is necessary to avoid loss of Faradic conversion efficiency with temperature and with fuel concentration

Autonomous Voltage Oscillations in a Direct Methanol Fuel Cell

International Nuclear Information System (INIS)

Nogueira, Jéssica A.; Peña Arias, Ivonne K.; Hanke-Rauschenbach, Richard; Vidakovic-Koch, Tanja; Varela, Hamilton; Sundmacher, Kai

2016-01-01

Proton exchange membrane fuel cells fed with H_2/CO mixtures at the anode have a considerably lower performance than fuel cells fed with pure hydrogen. However, when operated in an autonomous oscillatory regime, the overall voltage loss decreases due to a self-cleaning mechanism. Another molecule, also widely used as feed in the fuel cell and susceptible to kinetic instabilities, is methanol. To the best of our knowledge, there are no reports on autonomous voltage oscillations in the direct methanol fuel cell (DMFC). The purpose of this work was to explore if such instabilities also occur in the DMFC system. Initially, half-cell experiments with a gas diffusion electrode were performed. Then, a DMFC was operated under current control and studied by means of electrochemical impedance spectroscopy. The half-cell measurements revealed that the induction period for oscillations depends on the mass transfer conditions, where on stagnant electrode the induction time was shorter than in the case of forced convection. The DMFC showed also autonomous voltage oscillations above a certain threshold current. The results obtained by electrochemical impedance spectroscopy give evidence of a negative differential resistance in the fuel cell, hitherto not described in the literature, which can be related to the appearance of oscillations during galvanostatic methanol electro-oxidation. These results open the possibility to evaluate the performance of low-temperature fuel cells fed with carbon-containing fuels under oscillatory operating conditions.

Numerical simulation of direct methanol fuel cells using lattice Boltzmann method

Energy Technology Data Exchange (ETDEWEB)

Delavar, Mojtaba Aghajani; Farhadi, Mousa; Sedighi, Kurosh [Faculty of Mechanical Engineering, Babol University of Technology, Babol, P.O. Box 484 (Iran)

2010-09-15

In this study Lattice Boltzmann Method (LBM) as an alternative of conventional computational fluid dynamics method is used to simulate Direct Methanol Fuel Cell (DMFC). A two dimensional lattice Boltzmann model with 9 velocities, D2Q9, is used to solve the problem. The computational domain includes all seven parts of DMFC: anode channel, catalyst and diffusion layers, membrane and cathode channel, catalyst and diffusion layers. The model has been used to predict the flow pattern and concentration fields of different species in both clear and porous channels to investigate cell performance. The results have been compared well with results in literature for flow in porous and clear channels and cell polarization curves of the DMFC at different flow speeds and feed methanol concentrations. (author)

Micropump Fuel Mix Control for Novel Miniature Direct Methanol Fuel Cells, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The Energies and Power Densities of Direct Methanol Fuel Cells (DMFCs) are limited by the size and weight associated with the liquid pump, which must circulate the...

Performance of direct alcohol fuel cells fed with mixed methanol/ethanol solutions

Energy Technology Data Exchange (ETDEWEB)

Wongyao, N. [The Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, 126 Pracha-Uthit Rd., Bang Mod, Thung Khru, Bangkok 10140 (Thailand); Therdthianwong, A., E-mail: apichai.the@kmutt.ac.t [Fuel Cell and Hydrogen Research and Engineering Center, Clean Energy System Group, PDTI, King Mongkut' s University of Technology Thonburi, 126 Pracha-Uthit Rd., Bang Mod, Thung Khru, Bangkok 10140 (Thailand); Therdthianwong, S. [Department of Chemical Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, 126 Pracha-Uthit Rd., Bang Mod, Thung Khru, Bangkok 10140 (Thailand)

2011-07-15

Research highlights: {yields} We examined the performance of direct alcohol fuel cells fed with mixed alcohol. {yields} PtRu-PtSn/C and PtRu/C as catalysts for mixed alcohol electrooxidation reaction. {yields} Misplace adsorption of ethanol on PtRu/C caused the cell performance drop. {yields} PtRu/C showed higher performance than PtRu-PtSn/C for mixed alcohol fuel. -- Abstract: In combining the advantages of both methanol and ethanol, direct alcohol fuel cells fed with mixed alcohol solutions (1 M methanol and 1 M ethanol in varying volume ratios) were tested for performance. Employing a PtRu-PtSn/C catalyst as anode, cell performance was found to diminish rapidly even at 2.5% by volume ethanol mixture. Further increase of ethanol exceeded 10%, the cell performance gradually decreased and finally approached that of direct ethanol fuel cells. The causes of the decrease in the cell performance were the slow electro-oxidation of ethanol and the misplaced adsorption of ethanol on PtRu/C. By comparing the PtRu-PtSn/C cell with the PtRu/C cell operated with mixed alcohol solutions, the cell using PtRu/C as an anode catalyst provided higher power density since more PtRu/C surface was available for methanol oxidation reaction and less ohmic resistance of PtRu/C than that of PtRu-PtSn/C. In order to reach optimization of DAFC performance fed with mixed alcohol, the electrocatalyst used for the anode must selectively adsorb an alcohol, especially ethanol.

Performance of direct alcohol fuel cells fed with mixed methanol/ethanol solutions

International Nuclear Information System (INIS)

Wongyao, N.; Therdthianwong, A.; Therdthianwong, S.

2011-01-01

Research highlights: → We examined the performance of direct alcohol fuel cells fed with mixed alcohol. → PtRu-PtSn/C and PtRu/C as catalysts for mixed alcohol electrooxidation reaction. → Misplace adsorption of ethanol on PtRu/C caused the cell performance drop. → PtRu/C showed higher performance than PtRu-PtSn/C for mixed alcohol fuel. -- Abstract: In combining the advantages of both methanol and ethanol, direct alcohol fuel cells fed with mixed alcohol solutions (1 M methanol and 1 M ethanol in varying volume ratios) were tested for performance. Employing a PtRu-PtSn/C catalyst as anode, cell performance was found to diminish rapidly even at 2.5% by volume ethanol mixture. Further increase of ethanol exceeded 10%, the cell performance gradually decreased and finally approached that of direct ethanol fuel cells. The causes of the decrease in the cell performance were the slow electro-oxidation of ethanol and the misplaced adsorption of ethanol on PtRu/C. By comparing the PtRu-PtSn/C cell with the PtRu/C cell operated with mixed alcohol solutions, the cell using PtRu/C as an anode catalyst provided higher power density since more PtRu/C surface was available for methanol oxidation reaction and less ohmic resistance of PtRu/C than that of PtRu-PtSn/C. In order to reach optimization of DAFC performance fed with mixed alcohol, the electrocatalyst used for the anode must selectively adsorb an alcohol, especially ethanol.

Metamorphosis of the mixed phase PtRu anode catalyst for direct methanol fuel cells after exposure of methanol: In situ and ex situ characterizations

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Debasish [Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Aerosol Laboratory, Nano.DTU, Department of Chemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Chorkendorff, Ib [Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Johannessen, Tue [Aerosol Laboratory, Nano.DTU, Department of Chemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

2007-11-08

The change in the mixed phase heavily oxidized PtRu anode with the exposure of methanol in a direct methanol fuel cell (DMFC) has been investigated by electrochemical impedance spectroscopy (EIS) and X-ray diffraction (XRD). The investigation had two major objectives: (i) to explore the original state of the active catalyst and (ii) to understand if alloying of Pt and Ru is a requirement for higher methanol oxidation activity. It was found that the methanol oxidation activity gradually improved for {proportional_to}2 h of exposure. The impedance spectra were taken at different times within this time of improvement of activity. The impedance spectra were deconvoluted in different contributions like membrane resistance (R{sub m}), charge transfer resistance (R{sub Ct}), adsorption resistance (R{sub ad}), and oxidation resistance (R{sub ox}). The improvement of the activity was explained in terms of the effect of the pretreatment on different contributions. XRD was done on the virgin and methanol exposed sample as a possible mean to identify the difference. It was postulated that the reduction of the as prepared PtRu after exposure was responsible for the activity improvement. Also, it was shown that bulk alloy formation is not a necessary condition for higher methanol activity of PtRu catalysts. (author)

Combinatorial discovery of new methanol-tolerant non-noble metal cathode electrocatalysts for direct methanol fuel cells.

Science.gov (United States)

Yu, Jong-Sung; Kim, Min-Sik; Kim, Jung Ho

2010-12-14

Combinatorial synthesis and screening were used to identify methanol-tolerant non-platinum cathode electrocatalysts for use in direct methanol fuel cells (DMFCs). Oxygen reduction consumes protons at the surface of DMFC cathode catalysts. In combinatorial screening, this pH change allows one to differentiate active catalysts using fluorescent acid-base indicators. Combinatorial libraries of carbon-supported catalyst compositions containing Ru, Mo, W, Sn, and Se were screened. Ternary and quaternary compositions containing Ru, Sn, Mo, Se were more active than the "standard" Alonso-Vante catalyst, Ru(3)Mo(0.08)Se(2), when tested in liquid-feed DMFCs. Physical characterization of the most active catalysts by powder X-ray diffraction, gas adsorption, and X-ray photoelectron spectroscopy revealed that the predominant crystalline phase was hexagonal close-packed (hcp) ruthenium, and showed a surface mostly covered with oxide. The best new catalyst, Ru(7.0)Sn(1.0)Se(1.0), was significantly more active than Ru(3)Se(2)Mo(0.08), even though the latter contained smaller particles.

Nuclear magnetic resonance spectroscopic investigation of anode exhaust of direct methanol fuel cells without isotope enrichment

International Nuclear Information System (INIS)

Byun, Young Seok; Hwang, Reo Yun; Han, Ochee

2016-01-01

Fuel cells are devices that electrochemically convert the chemical energy of fuels such as natural gas, gasoline, and methanol, into electricity. Fuel cells more efficiently use energy than internal combustion engines and do not produce undesirable pollutants, such as NO_x ,SO_x and particulates. Fuel cells can be distinguished from one another by their electrolytes. Among the various direct alcohol fuel cells, direct methanol fuel cells (DMFCs) have been developed most. However, DMFCs have several practical problems such as methanol crossove r from an anode to a cathode and slow methanol oxidation reaction rates. Therefore, understanding the electrochemical reaction mechanisms of DMFCs may provide clues to solve these problems, and various analytical methods have been employed to examine these mechanisms. We demonstrated that "1H and "1"3C NMR spectroscopy can be used for analyzing anode exhausts of DMFCs operated with methanol without any isotope enrichment. However, the low sensitivity of NMR spectroscopy hindered our efforts to detect minor reaction intermediates. Therefore, sensitivity enhancement techniques such as dynamic nuclear polarization (DNP) NMR methods and/or presaturation methods to increase the dynamic range of the proton spectra by pre-saturating large water signals, are expected to be useful to detect low-concentration species

Nuclear magnetic resonance spectroscopic investigation of anode exhaust of direct methanol fuel cells without isotope enrichment

Energy Technology Data Exchange (ETDEWEB)

Byun, Young Seok; Hwang, Reo Yun; Han, Ochee [Western Seoul Center, Korea Basic Science Institute, Seoul (Korea, Republic of)

2016-12-15

Fuel cells are devices that electrochemically convert the chemical energy of fuels such as natural gas, gasoline, and methanol, into electricity. Fuel cells more efficiently use energy than internal combustion engines and do not produce undesirable pollutants, such as NO{sub x} ,SO{sub x} and particulates. Fuel cells can be distinguished from one another by their electrolytes. Among the various direct alcohol fuel cells, direct methanol fuel cells (DMFCs) have been developed most. However, DMFCs have several practical problems such as methanol crossove r from an anode to a cathode and slow methanol oxidation reaction rates. Therefore, understanding the electrochemical reaction mechanisms of DMFCs may provide clues to solve these problems, and various analytical methods have been employed to examine these mechanisms. We demonstrated that {sup 1}H and {sup 13}C NMR spectroscopy can be used for analyzing anode exhausts of DMFCs operated with methanol without any isotope enrichment. However, the low sensitivity of NMR spectroscopy hindered our efforts to detect minor reaction intermediates. Therefore, sensitivity enhancement techniques such as dynamic nuclear polarization (DNP) NMR methods and/or presaturation methods to increase the dynamic range of the proton spectra by pre-saturating large water signals, are expected to be useful to detect low-concentration species.

Synthesis of Pd₃Co₁@Pt/C core-shell catalysts for methanol-tolerant cathodes of direct methanol fuel cells.

Science.gov (United States)

Aricò, Antonino S; Stassi, Alessandro; D'Urso, Claudia; Sebastián, David; Baglio, Vincenzo

2014-08-18

A composite Pd-based electrocatalyst consisting of a surface layer of Pt (5 wt.%) supported on a core Pd3Co1 alloy (95 wt.%) and dispersed as nanoparticles on a carbon black support (50 wt.% metal content) was prepared by using a sulphite-complex route. The structure, composition, morphology, and surface properties of the catalyst were investigated by XRD, XRF, TEM, XPS and low-energy ion scattering spectroscopy (LE-ISS). The catalyst showed an enrichment of Pt on the surface and a smaller content of Co in the outermost layers. These characteristics allow a decrease the Pt content in direct methanol fuel cell cathode electrodes (from 1 to 0.06 mg cm(-2)) without significant decay in performance, due also to a better tolerance to methanol permeated through the polymer electrolyte membrane. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Proton conducting hydrocarbon membranes: Performance evaluation for room temperature direct methanol fuel cells

International Nuclear Information System (INIS)

Krivobokov, Ivan M.; Gribov, Evgeniy N.; Okunev, Alexey G.

2011-01-01

The methanol permeability, proton conductivity, water uptake and power densities of direct methanol fuel cells (DMFCs) at room temperature are reported for sulfonated hydrocarbon (sHC) and perfluorinated (PFSA) membranes from Fumatech, and compared to Nafion membranes. The sHC membranes exhibit lower proton conductivity (25-40 mS cm -1 vs. ∼95-40 mS cm -1 for Nafion) as well as lower methanol permeability (1.8-3.9 x 10 -7 cm 2 s -1 vs. 2.4-3.4 x 10 -6 cm 2 s -1 for Nafion). Water uptake was similar for all membranes (18-25 wt%), except for the PFSA membrane (14 wt%). Methanol uptake varied from 67 wt% for Nafion to 17 wt% for PFSA. The power density of Nafion in DMFCs at room temperature decreases with membrane thickness from 26 mW cm -2 for Nafion 117 to 12.5 mW cm -2 for Nafion 112. The maximum power density of the Fumatech membranes ranges from 4 to 13 mW cm -1 . Conventional transport parameters such as membrane selectivity fail to predict membrane performance in DMFCs. Reliable and easily interpretable results are obtained when the power density is plotted as a function of the transport factor (TF), which is the product of proton concentration in the swollen membrane and the methanol flux. At low TF values, cell performance is limited by low proton conductivity, whereas at high TF values it decreases due to methanol crossover. The highest maximum power density corresponds to intermediate values of TF.

A quasi-direct methanol fuel cell system based on blend polymer membrane electrolytes

DEFF Research Database (Denmark)

Li, Qingfeng; Hjuler, Hans Aage; Hasiotis, C.

2002-01-01

, compared to less than 100 ppm CO for the Nafion-based technology at 80degrees C. The high CO tolerance makes it possible to use the reformed hydrogen directly from a simple methanol reformer without further CO removal. That both the fuel cell and the methanol reformer operate at temperatures around 200......On the basis of blend polymer electrolytes of polybenzimidazole and sulfonated polysulfone, a polymer electrolyte membrane fuel cell was developed with an operational temperature up to 200degrees C. Due to the high operational temperature, the fuel cell can tolerate 1.0-3.0 vol % CO in the fuel...

A microfluidic-structured flow field for passive direct methanol fuel cells operating with highly concentrated fuels

International Nuclear Information System (INIS)

Wu, Q X; Zhao, T S; Chen, R; Yang, W W

2010-01-01

Conventional direct methanol fuel cells (DMFCs) have to operate with excessively diluted methanol solutions to limit methanol crossover and its detrimental consequences. Operation with such diluted methanol solutions not only results in a significant penalty in the specific energy of the power pack, limiting the runtime of this type of fuel cell, but also lowers the cell performance and operating stability. In this paper, a microfluidic-structured anode flow field for passive DMFCs with neither liquid pumps nor gas compressors/blowers is developed. This flow field consists of plural micro flow passages. Taking advantage of the liquid methanol and gas CO 2 two-phase counter flow, the unique fluidic structure enables the formation of a liquid–gas meniscus in each flow passage. The evaporation from the small meniscus in each flow passage can lead to an extremely large interfacial mass-transfer resistance, creating a bottleneck of methanol delivery to the anode CL. The fuel cell tests show that the innovative flow field allows passive DMFCs to achieve good cell performance with a methanol concentration as high as 18.0 M, increasing the specific energy of the DMFC system by about five times compared with conventional designs.

Enrichment and detection of microorganisms involved in direct and indirect methanogenesis from methanol in an anaerobic thermophilic bioreactor

NARCIS (Netherlands)

Roest, de K.; Altinbas, M.; Paulo, P.L.; Heilig, H.G.H.J.; Akkermans, A.D.L.; Smidt, H.; Vos, de W.M.; Stams, A.J.M.

2005-01-01

To gain insight into the microorganisms involved in direct and indirect methane formation from methanol in a laboratory-scale thermophilic (55°C) methanogenic bioreactor, reactor sludge was disrupted and serial dilutions were incubated in specific growth media containing methanol and possible

Modeling of the Transport Phenomena in Passive Direct Methanol Fuel Cells Using a Two-Phase Anisotropic Model

Directory of Open Access Journals (Sweden)

Zheng Miao

2014-04-01

Full Text Available The transport phenomena in a passive direct methanol fuel cell (DMFC were numerically simulated by the proposed two-dimensional two-phase nonisothermal mass transport model. The anisotropic transport characteristic and deformation of the gas diffusion layer (GDL were considered in this model. The natural convection boundary conditions were adopted for the transport of methanol, oxygen, and heat at the GDL outer surface. The effect of methanol concentration in the reservoir on cell performance was examined. The distribution of multiphysical fields in the membrane electrode assembly (MEA, especially in the catalyst layers (CLs, was obtained and analyzed. The results indicated that transport resistance for the methanol mainly existed in the MEA while that for oxygen and heat was primarily due to natural convection at the GDL outer surface. Because of the relatively high methanol concentration, the local reaction rate in CLs was mainly determined by the overpotential. Methanol concentration between 3 M and 4 M was recommended for passive liquid feed DMFC in order to achieve a balance between the cell performance and the methanol crossover.

Mixtures of methanol and 2-propanol as a potential fuel for direct alcohol fuel cells

Directory of Open Access Journals (Sweden)

S. LJ. GOJKOVIC

2007-12-01

Full Text Available The electrochemical oxidation of methanol, 2-propanol, and their mixtures was investigated on a Pt/C thin film electrode in acid solution. It was confirmed that the oxidation of 2-propanol commences at less positive potentials than that of methanol and exhibits significantly higher oxidation current densities at low potentials. When both methanol and 2-propanol were present in the solution, the onset of the oxidation current was the same as for the oxidation of pure 2-propanol. Although both alcohols inhibit the oxidation reaction of each other to a certain extent, steady-state polarization measurements showed that their mixture provides higher current densities than single alcohols over the entire potential region from the hydrogen region to oxide formation on the Pt surface. This implies that the addition of 2-propanol into the fuel may extend the operational range of direct methanol fuel cells.

In situ synthesis of nanocomposite membranes: comprehensive improvement strategy for direct methanol fuel cells.

Science.gov (United States)

Rao, Siyuan; Xiu, Ruijie; Si, Jiangju; Lu, Shanfu; Yang, Meng; Xiang, Yan

2014-03-01

In situ synthesis is a powerful approach to control nanoparticle formation and consequently confers extraordinary properties upon composite membranes relative to conventional doping methods. Herein, uniform nanoparticles of cesium hydrogen salts of phosphotungstic acid (CsPW) are controllably synthesized in situ in Nafion to form CsPW–Nafion nanocomposite membranes with both improved proton conductivity and methanol-crossover suppression. A 101.3% increase of maximum power density has been achieved relative to pristine Nafion in a direct methanol fuel cell (DMFC), indicating a potential pathway for large-scale fabrication of DMFC alternative membranes.

Effects of dissolved iron and chromium on the performance of direct methanol fuel cell

International Nuclear Information System (INIS)

Chen, Weimin; Xin, Qin; Sun, Gongquan; Yang, Shaohua; Zhou, Zhenhua; Mao, Qing; Sun, Pichang

2007-01-01

Effects of Fe 3+ and Cr 3+ ions on the performance of direct methanol fuel cell were investigated. The results show that the cell performance decreased remarkably when the concentration of Fe 3+ or Cr 3+ exceeded 1 x 10 -4 mol L -1 . Fe 3+ displayed a strong negative effect on the catalytic oxidation of methanol, while Cr 3+ affected the cell performance primarily by exchanging with protons of the membrane/ionomer and resulted in ionic conductivity losses. Complete recovery of the cell performance was not obtained after flushing the cell with deionized water

Experimental Validation of Methanol Crossover in a Three-dimensional, Two-Fluid Model of a Direct Methanol Fuel Cell

DEFF Research Database (Denmark)

Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

2012-01-01

A fully coupled three-dimensional, steady-state, two-fluid, multi-component and non-isothermal DMFC model has been developed in the commercial CFD package CFX 13 (ANSYS inc.). It accounts for the presence of micro porous layers, non-equilibrium phase change, and methanol and water uptake...... in the ionomer phase of the catalytic layer, and detailed membrane transport of methanol and water. In order to verify the models ability to predict methanol crossover, simulation results are compared with experimental measurements under different current densities along with air and methanol stoichiometries....... Methanol crossover is indirectly measured based on the combined anode and cathode exhaust CO2 mole fraction and by accounting for the CO2 production at the anode as a function of current density. This approach is simple and assumes that all crossed over methanol is oxidized. Moreover, it takes CO2...

Two-phase, mass-transport model for direct methanol fuel cells with effect of non-equilibrium evaporation and condensation

Science.gov (United States)

Yang, W. W.; Zhao, T. S.

A two-phase, mass-transport model for liquid-feed direct methanol fuel cells (DMFCs) is developed by taking into account the effect of non-equilibrium evaporation and condensation of methanol and water. The comparison between the present model and other models indicates that the present model yields more reasonable predictions of cell performance. Particularly, it is shown that the models that invoke a thermodynamic-equilibrium assumption between phases will overestimate mass-transport rates of methanol and water, thereby resulting in an inaccurate prediction of cell performance. The parametric study using the present model reveals that the gas coverage at the flow channel-diffusion-layer interface is directly related to the gas-void fraction inside the anode porous region; increasing the gas-void fraction will increase the mass-transfer resistance of methanol and thus lower cell performance. The effects of the geometric dimensions of the cell structure, such as channel width and rib width, on cell performance are also investigated with the model developed in this work.

Mould Design and Material selection for Film Insert Moulding of Direct Methanol Fuel Cell Packaging

DEFF Research Database (Denmark)

Wöhner, Timo; Senkbeil, S.; Olesen, T. L.

2015-01-01

This paper presents the mould design for an injection moulding (IM) process for the production of a methanol container for the use in small, passive Direct Methanol Fuel Cell (DMFC) systems, which are intended to be used in behind-the-ear hearing aid systems. One of the crucial properties...... for the production of containers with different venting area and location of the venting holes and the use of different membrane thicknesses by using the same mould. Mould design and material selection are presented....

Fabrication of graphene-fullerene hybrid by self-assembly and its application as support material for methanol electrocatalytic oxidation reaction

Science.gov (United States)

Zhang, Xuan; Zhang, Jia-Wei; Xiang, Ping-Hua; Qiao, Jinli

2018-05-01

Graphene-fullerene hybrids were facilely fabricated by self-assembly of graphene oxide (GO) and multi-substituted fulleropyrrolidines (PyrC60). The hybrids (GO-PyrC60) were applied as support materials to deposit Pd nanoparticle catalyst by a simple hydrothermal co-reduction approach. The as-prepared electrocatalysts (Pd/RGO-PyrC60) were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The RGO-PyrC60 hybrid supported Pd catalyst with the optimal ratio of RGO to PyrC60, exhibited much enhanced electrocatalytic activity and stability toward methanol oxidation reaction (MOR) compared to the RGO alone supported Pd as well as commercial Pd/C. The introduction of fulleropyrrolidine as spacer between graphene layers could increase the electrocatalytic activity and improve the long-term stability. This strategy may contribute to developing graphene-fullerene hydrids as effective support materials for advanced electrocatalysts.

Waste-to-methanol: Process and economics assessment.

Science.gov (United States)

Iaquaniello, Gaetano; Centi, Gabriele; Salladini, Annarita; Palo, Emma; Perathoner, Siglinda; Spadaccini, Luca

2017-11-01

The waste-to-methanol (WtM) process and related economics are assessed to evidence that WtM is a valuable solution both from economic, strategic and environmental perspectives. Bio-methanol from Refuse-derived-fuels (RdF) has an estimated cost of production of about 110€/t for a new WtM 300t/d plant. With respect to waste-to-energy (WtE) approach, this solution allows various advantages. In considering the average market cost of methanol and the premium as biofuel, the WtM approach results in a ROI (Return of Investment) of about 29%, e.g. a payback time of about 4years. In a hybrid scheme of integration with an existing methanol plant from natural gas, the cost of production becomes a profit even without considering the cap for bio-methanol production. The WtM process allows to produce methanol with about 40% and 30-35% reduction in greenhouse gas emissions with respect to methanol production from fossil fuels and bio-resources, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Model-based analysis of water management in alkaline direct methanol fuel cells

Science.gov (United States)

Weinzierl, C.; Krewer, U.

2014-12-01

Mathematical modelling is used to analyse water management in Alkaline Direct Methanol Fuel Cells (ADMFCs) with an anion exchange membrane as electrolyte. Cathodic water supply is identified as one of the main challenges and investigated at different operation conditions. Two extreme case scenarios are modelled to study the feasible conditions for sufficient water supply. Scenario 1 reveals that water supply by cathodic inlet is insufficient and, thus, water transport through membrane is essential for ADMFC operation. The second scenario is used to analyse requirements on water transport through the membrane for different operation conditions. These requirements are influenced by current density, evaporation rate, methanol cross-over and electro-osmotic drag of water. Simulations indicate that water supply is mainly challenging for high current densities and demands on high water diffusion are intensified by water drag. Thus, current density might be limited by water transport through membrane. The presented results help to identify important effects and processes in ADMFCs with a polymer electrolyte membrane and to understand these processes. Furthermore, the requirements identified by modelling show the importance of considering water transport through membrane besides conductivity and methanol cross-over especially for designing new membrane materials.

Development of cesium phosphotungstate salt and chitosan composite membrane for direct methanol fuel cells.

Science.gov (United States)

Xiao, Yanxin; Xiang, Yan; Xiu, Ruijie; Lu, Shanfu

2013-10-15

A novel composite membrane has been developed by doping cesium phosphotungstate salt (CsxH3-xPW12O40 (0≤x≤3), Csx-PTA) into chitosan (CTS/Csx-PTA) for application in direct methanol fuel cells (DMFCs). Uniform distribution of Csx-PTA nanoparticles has been achieved in the chitosan matrix. The proton conductivity of the composite membrane is significantly affected by the Csx-PTA content in the composite membrane as well as the Cs substitution in PTA. The highest proton conductivity for the CTS/Csx-PTA membranes was obtained with x=2 and Cs2-PTA content of 5 wt%. The value is 6×10(-3) S cm(-1) and 1.75×10(-2) S cm(-1) at 298 K and 353 K, respectively. The methanol permeability of CTS/Cs2-PTA membrane is about 5.6×10(-7), 90% lower than that of Nafion-212 membrane. The highest selectivity factor (φ) was obtained on CTS/Cs2-PTA-5 wt% composite membrane, 1.1×10(4)/Scm(-3)s. The present study indicates the promising potential of CTS/Csx-PTA composite membrane as alternative proton exchange membranes in direct methanol fuel cells. Copyright © 2013 Elsevier Ltd. All rights reserved.

A CNT (carbon nanotube) paper as cathode gas diffusion electrode for water management of passive μ-DMFC (micro-direct methanol fuel cell) with highly concentrated methanol

International Nuclear Information System (INIS)

Deng, Huichao; Zhang, Yufeng; Zheng, Xue; Li, Yang; Zhang, Xuelin; Liu, Xiaowei

2015-01-01

A novel MEA (membrane electrode assembly) structure of passive μ-DMFC (micro-direct methanol fuel cell) controls water management and decreases methanol crossover. The CNT (carbon nanotube) paper replacing CP (carbon paper) as GDL (gas diffusion paper) enhances water back diffusion which passively prevents flooding in the cathode and promotes low methanol crossover. Moreover, the unique structure of CNT paper can also enhance efficiency of oxygen mass transport and catalyst utilization. The passive μ-DMFC with CNT-MEA exhibits significantly higher performance than passive μ-DMFC with CP-MEA and can operate in high methanol concentration, showing the peak power density of 23.2 mW cm −2 . The energy efficiency and fuel utilization efficiency are obviously improved from 11.54% to 22.7% and 36.61%–49.34%, respectively, and the water transport coefficient is 0.47 which is lower than previously reported passive μ-DMFC with CP. - Highlights: • This novel GDL (gas diffusion layer) solves water management and methanol crossover. • This GDL creates a hydraulic pressure in the cathode increasing water back diffusion. • This GDL improves the electrical conductivity and activity of catalyst

Functional separation of oxidation–reduction reactions and electron transport in PtRu/ND and conductive additive hybrid electrocatalysts during methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yan; Wang, Yanhui [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Bian, Linyan [College of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, Henan 454000 (China); Lu, Rui [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Zang, Jianbing, E-mail: jbzang@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

2016-02-28

Graphical abstract: - Highlights: • Functional separation of reactions and electron transport in PtRu/ND + AB (or CNT). • A conductive network was formed after the addition of AB or CNT. • PtRu/ND + AB (or CNT) exhibited enhanced activity and stability than PtRu/ND. - Abstract: Undoped nanodiamond (ND) supported PtRu (PtRu/ND) electrocatalyst for methanol oxidation reactions (MOR) in direct methanol fuel cells was prepared by a microwave-assisted polyol reduction method. Sp{sup 3}-bonded ND possesses high electrochemical stability but low conductivity, while sp{sup 2}-bonded carbon nanomaterials with high conductivity are prone to oxidation. Therefore, the functions of the supporting material were separated in this study. ND (sp{sup 3}), as a support, and AB or CNTs (sp{sup 2}), as a conductive additive, were combined to form the hybrid electrocatalysts PtRu/ND + AB and PtRu/ND + CNT for MOR. The morphology of the electrocatalysts was characterized by scanning electron microscopy and electrochemical measurements were performed using an electrochemical workstation. The results indicated that the electrocatalytic activity of PtRu/ND for MOR was improved with the addition of AB or CNTs as a conductive additive. Moreover, adding CNTs to PtRu/ND as a conductive additive showed better electrocatalytic activities than adding AB, which can be ascribed to the better electron-transfer ability of CNTs.

A direct methanol fuel cell system to power a humanoid robot

Science.gov (United States)

Joh, Han-Ik; Ha, Tae Jung; Hwang, Sang Youp; Kim, Jong-Ho; Chae, Seung-Hoon; Cho, Jae Hyung; Prabhuram, Joghee; Kim, Soo-Kil; Lim, Tae-Hoon; Cho, Baek-Kyu; Oh, Jun-Ho; Moon, Sang Heup; Ha, Heung Yong

In this study, a direct methanol fuel cell (DMFC) system, which is the first of its kind, has been developed to power a humanoid robot. The DMFC system consists of a stack, a balance of plant (BOP), a power management unit (PMU), and a back-up battery. The stack has 42 unit cells and is able to produce about 400 W at 19.3 V. The robot is 125 cm tall, weighs 56 kg, and consumes 210 W during normal operation. The robot is integrated with the DMFC system that powers the robot in a stable manner for more than 2 h. The power consumption by the robot during various motions is studied, and load sharing between the fuel cell and the back-up battery is also observed. The loss of methanol feed due to crossover and evaporation amounts to 32.0% and the efficiency of the DMFC system in terms of net electric power is 22.0%.

MnO2/CNT supported Pt and PtRu nanocatalysts for direct methanol fuel cells.

Science.gov (United States)

Zhou, Chunmei; Wang, Hongjuan; Peng, Feng; Liang, Jiahua; Yu, Hao; Yang, Jian

2009-07-07

Pt/MnO2/carbon nanotube (CNT) and PtRu/MnO2/CNT nanocomposites were synthesized by successively loading hydrous MnO2 and Pt (or PtRu alloy) nanoparticles on CNTs and were used as anodic catalysts for direct methanol fuel cells (DMFCs). The existence of MnO2 on the surface of CNTs effectively increases the proton conductivity of the catalyst, which then could remarkably improve the performance of the catalyst in methanol electro-oxidation. As a result, Pt/MnO2/CNTs show higher electrochemical active surface area and better methanol electro-oxidation activity, compared with Pt/CNTs. As PtRu alloy nanoparticles were deposited on the surface of MnO2/CNTs instead of Pt, the PtRu/MnO2/CNT catalyst shows not only excellent electro-oxidation activity to methanol with forward anodic peak current density of 901 A/gPt but also good CO oxidation ability with lower preadsorbed CO oxidation onset potential (0.33 V vs Ag/AgCl) and peak potential (0.49 V vs Ag/AgCl) at room temperature.

Methyl phosphate formation as a major degradation mode of direct methanol fuel cells with phosphoric acid based electrolytes

DEFF Research Database (Denmark)

Aili, David; Vassiliev, Anton; Jensen, Jens Oluf

2015-01-01

Phosphoric acid and phosphoric acid doped polymer membranes are widely used as electrolytes in hydrogen based fuel cells operating at elevated temperatures. Such electrolytes have been explored for direct oxidation of methanol to further increase the versatility of the systems, however......, with demonstrated lifetimes of only a few days to weeks. In this work the methyl phosphate formation from the acid and methanol is identified and proposed to be a major mechanism for the cell degradation. Proton conductivity and fuel cell durability tests validate the mechanism at high methanol contents....

Enrichment and detection of microorganisms involved in direct and indirect methanogenesis from methanol in an anaerobic thermophilic bioreactor.

Science.gov (United States)

Roest, Kees; Altinbas, Mahmut; Paulo, Paula L; Heilig, H G H J; Akkermans, Antoon D L; Smidt, Hauke; de Vos, Willem M; Stams, Alfons J M

2005-10-01

To gain insight into the microorganisms involved in direct and indirect methane formation from methanol in a laboratory-scale thermophilic (55 degrees C) methanogenic bioreactor, reactor sludge was disrupted and serial dilutions were incubated in specific growth media containing methanol and possible intermediates of methanol degradation as substrates. With methanol, growth was observed up to a dilution of 10(8). However, when Methanothermobacter thermoautotrophicus strain Z245 was added for H2 removal, growth was observed up to a 10(10)-fold dilution. With H2/CO2 and acetate, growth was observed up to dilutions of 10(9) and 10(4), respectively. Dominant microorganisms in the different dilutions were identified by 16S rRNA-gene diversity and sequence analysis. Furthermore, dilution polymerase chain reaction (PCR) revealed a similar relative abundance of Archaea and Bacteria in all investigated samples, except in enrichment with acetate, which contained 100 times less archaeal DNA than bacterial DNA. The most abundant bacteria in the culture with methanol and strain Z245 were most closely related to Moorella glycerini. Thermodesulfovibrio relatives were found with high sequence similarity in the H2/CO2 enrichment, but also in the original laboratory-scale bioreactor sludge. Methanothermobacter thermoautotrophicus strains were the most abundant hydrogenotrophic archaea in the H2/CO2 enrichment. The dominant methanol-utilizing methanogen, which was present in the 10(8)-dilution, was most closely related to Methanomethylovorans hollandica. Compared to direct methanogenesis, results of this study indicate that syntrophic, interspecies hydrogen transfer-dependent methanol conversion is equally important in the thermophilic bioreactor, confirming previous findings with labeled substrates and specific inhibitors.

Effect of fumigation methanol and ethanol on the gaseous and particulate emissions of a direct-injection diesel engine

Science.gov (United States)

Zhang, Z. H.; Tsang, K. S.; Cheung, C. S.; Chan, T. L.; Yao, C. D.

2011-02-01

Experiments were conducted on a four-cylinder direct-injection diesel engine with methanol or ethanol injected into the air intake of each cylinder, to compare their effect on the engine performance, gaseous emissions and particulate emissions of the engine under five engine loads at the maximum torque speed of 1800 rev/min. The methanol or ethanol was injected to top up 10% and 20% of the engine loads under different engine operating conditions. The experimental results show that both fumigation methanol and fumigation ethanol decrease the brake thermal efficiency (BTE) at low engine load but improves it at high engine load; however the fumigation methanol has higher influence on the BTE. Compared with Euro V diesel fuel, fumigation methanol or ethanol could lead to reduction of both NOx and particulate mass and number emissions of the diesel engine, with fumigation methanol being more effective than fumigation ethanol in particulate reduction. The NOx and particulate reduction is more effective with increasing level of fumigation. However, in general, fumigation fuels increase the HC, CO and NO 2 emissions, with fumigation methanol leading to higher increase of these pollutants. Compared with ethanol, the fumigation methanol has stronger influence on the in-cylinder gas temperature, the air/fuel ratio, the combustion processes and hence the emissions of the engine.

Dynamic Modeling and Plantwide Control of a Hybrid Power and Chemical Plant: An Integrated Gasification Combined Cycle Coupled with a Methanol Plant

Science.gov (United States)

Robinson, Patrick J.

Gasification has been used in industry on a relatively limited scale for many years, but it is emerging as the premier unit operation in the energy and chemical industries. The switch from expensive and insecure petroleum to solid hydrocarbon sources (coal and biomass) is occurring due to the vast amount of domestic solid resources, national security and global warming issues. Gasification (or partial oxidation) is a vital component of "clean coal" technology. Sulfur and nitrogen emissions can be reduced, overall energy efficiency is increased and carbon dioxide recovery and sequestration are facilitated. Gasification units in an electric power generation plant produce a fuel gas for driving combustion turbines. Gasification units in a chemical plant generate synthesis gas, which can be used to produce a wide spectrum of chemical products. Future plants are predicted to be hybrid power/chemical plants with gasification as the key unit operation. The coupling of an Integrated Gasification Combined Cycle (IGCC) with a methanol plant can handle swings in power demand by diverting hydrogen gas from a combustion turbine and synthesis gas from the gasifier to a methanol plant for the production of an easily-stored, hydrogen-consuming liquid product. An additional control degree of freedom is provided with this hybrid plant, fundamentally improving the controllability of the process. The idea is to base-load the gasifier and use the more responsive gas-phase units to handle disturbances. During the summer days, power demand can fluctuate up to 50% over a 12-hour period. The winter provides a different problem where spikes of power demand can go up 15% within the hour. The following dissertation develops a hybrid IGCC / methanol plant model, validates the steady-state results with a National Energy Technical Laboratory study, and tests a proposed control structure to handle these significant disturbances. All modeling was performed in the widely used chemical process

Influencing parameters of water and methanol transport in a big direct methanol fuel cell; Einflussgroessen auf den Wasser- und Methanoltransport einer groesseren Direkt-Methanol Brennstoffzelle

Energy Technology Data Exchange (ETDEWEB)

Schonert, Morten

2008-07-01

The author investigated the influencing parameters of water and methanol transport in a big direct methanol fuel cell (Pel > 1 kW) with the intention of making the direct methanol fuel cell system water-autonomous. As water is consumed during the electrochemical reaction on the anode while more water is produced on the cathode, the difference must be removed via the air. Any further water produced on the cathode must be condensed and recirculated to the anode. With increasing ambient temperature, the air volume flow must be reduced because otherwise more water would be removed than is acceptable. Low air volume flow on the cathode causes unstable cell voltage, which is also assumed to be caused by excess water production. For this reason, an attempt was made to prevent excess water production on the cathode by a system engineering approach. It was found that at the low air volume flow required for water autonomy, water permeation through the membrane-electrode aggregate (MEA) depends on the uptake capacity and on the time of residue of air over the cathode and less on the cathode material. Water permeation stops when the concentration gradient is balanced. Apart from the water permeation, there is also water transport through the Nafion {sup registered} membrane, i.e. so-called electroosmotic drag (ESD). This is an active transport mechanism that can also work against a concentration gradient. It could be shown that the EOD can be reduced by using water-impermeable materials for the gas diffusion layer on the anode. This will reduce the water volume that reaches the membrane, i.e. the water on the cathode. On the other hand, there was no measurable effect of the cathode design on water or methanol transport. The electrochemical performance of the membrane-electrode units under investigation was robust in case of many influencing parameters, e.g. dispersion, the conditions of MEA fabrication by hot pressing, themembrane thickness and the rate of methanol permeation

Ni2P Makes Application of the PtRu Catalyst Much Stronger in Direct Methanol Fuel Cells.

Science.gov (United States)

Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei

2015-10-12

PtRu is regarded as the best catalyst for direct methanol fuel cells, but the performance decay resulting from the loss of Ru seriously hinders commercial applications. Herein, we demonstrated that the presence of Ni2 P largely reduces Ru loss, which thus makes the application of PtRu much stronger in direct methanol fuel cells. Outstanding catalytic activity and stability were observed by cyclic voltammetry. Upon integrating the catalyst material into a practical direct methanol fuel cell, the highest maximum power density was achieved on the PtRu-Ni2P/C catalyst among the reference catalysts at different temperatures. A maximum power density of 69.9 mW cm(-2) at 30 °C was obtained on PtRu-Ni2P/C, which is even higher than the power density of the state-of-the-art commercial PtRu catalyst at 70 °C (63.1 mW cm(-2)). Moreover, decay in the performance resulting from Ru loss was greatly reduced owing to the presence of Ni2 P, which is indicative of very promising applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mordenite/Nafion and analcime/Nafion composite membranes prepared by spray method for improved direct methanol fuel cell performance

Science.gov (United States)

Prapainainar, Paweena; Du, Zehui; Kongkachuichay, Paisan; Holmes, Stuart M.; Prapainainar, Chaiwat

2017-11-01

The aim of this work was to improve proton exchange membranes (PEMs) used in direct methanol fuel cells (DMFCs). A membrane with a high proton conductivity and low methanol permeability was required. Zeolite filler in Nafion (NF matrix) composite membranes were prepared using two types of zeolite, mordenite (MOR) and analcime (ANA). Spray method was used to prepare the composite membranes, and properties of the membranes were investigated: mechanical properties, solubility, water and methanol uptake, ion-exchange capacity (IEC), proton conductivity, methanol permeability, and DMFC performance. It was found that MOR filler showed higher performance than ANA. The MOR/Nafion composite membrane gave better properties than ANA/Nafion composite membrane, including a higher proton conductivity and a methanol permeability that was 2-3 times lower. The highest DMFC performance (10.75 mW cm-2) was obtained at 70 °C and with 2 M methanol, with a value 1.5 times higher than that of ANA/Nafion composite membrane and two times higher than that of commercial Nafion 117 (NF 117).

Graphene-derived Fe/Co-N-C catalyst in direct methanol fuel cells: Effects of the methanol concentration and ionomer content on cell performance

Science.gov (United States)

Park, Jong Cheol; Choi, Chang Hyuck

2017-08-01

Non-precious metal catalysts (typically Fe(Co)-N-C catalysts) have been widely investigated for use as cost-effective cathode materials in low temperature fuel cells. Despite the high oxygen reduction activity and methanol-tolerance of graphene-based Fe(Co)-N-C catalysts in an acidic medium, their use in direct methanol fuel cells (DMFCs) has not yet been successfully implemented, and only a few studies have investigated this topic. Herein, we synthesized a nano-sized graphene-derived Fe/Co-N-C catalyst by physical ball-milling and a subsequent chemical modification of the graphene oxide. Twelve membrane-electrode-assemblies are fabricated with various cathode compositions to determine the effects of the methanol concentration, ionomer (i.e. Nafion) content, and catalyst loading on the DMFC performance. The results show that a graphene-based catalyst is capable of tolerating a highly-concentrated methanol feed up to 10.0 M. The optimized electrode composition has an ionomer content and catalyst loading of 66.7 wt% and 5.0 mg cm-2, respectively. The highest maximum power density is ca. 32 mW cm-2 with a relatively low PtRu content (2 mgPtRu cm-2). This study overcomes the drawbacks of conventional graphene-based electrodes using a nano-sized graphene-based catalyst and further shows the feasibility of their potential applications in DMFC systems.

Thin Film Catalyst Layers for Direct Methanol Fuel Cells

Science.gov (United States)

Witham, C. K.; Chun, W.; Ruiz, R.; Valdez, T. I.; Narayanan, S. R.

2000-01-01

One of the primary obstacles to the widespread use of the direct methanol fuel cell (DMFC) is the high cost of the catalyst. Therefore, reducing the catalyst loading well below the current level of 8-12 mg/cm 2 would be important to commercialization. The current methods for preparation of catalyst layers consisting of catalyst, ionomer and sometimes a hydrophobic additive are applied by either painting, spraying, decal transfer or screen printing processes. Sputter deposition is a coating technique widely used in manufacturing and therefore particularly attractive. In this study we have begun to explore sputtering as a method for catalyst deposition. Present experiments focus on Pt-Ru catalyst layers for the anode.

A Graphite Oxide Paper Polymer Electrolyte for Direct Methanol Fuel Cells

Directory of Open Access Journals (Sweden)

Ravi Kumar

2011-01-01

Full Text Available A flow directed assembly of graphite oxide solution was used in the formation of free-standing graphene oxide paper of approximate thickness of 100 μm. The GO papers were characterised by XRD and SEM. Electrochemical characterization of the GO paper membrane electrode assembly revealed proton conductivities of 4.1 × 10−2 S cm−1 to 8.2 × 10−2 S cm−1 at temperatures of 25–90°C. A direct methanol fuel cell, at 60°C, gave a peak power density of 8 mW cm−2 at a current density of 35 mA cm−2.

Proton conducting semi-IPN based on Nafion and crosslinked poly(AMPS) for direct methanol fuel cell

International Nuclear Information System (INIS)

Cho, Ki-Yun; Jung, Ho-Young; Shin, Seung-Shik; Choi, Nam-Soon; Sung, Shi-Joon; Park, Jung-Ki; Choi, Jong-Ho; Park, Kyung-Won; Sung, Yung-Eun

2004-01-01

For direct methanol fuel cell, the proton conducting membrane based on semi-interpenetrating polymer networks (IPNs) of Nafion and crosslinked poly(AMPS) was prepared and characterized. The modification of Nafion with crosslinked poly(AMPS) such as hydrocarbon polymer changed the state of water in membranes. Without a significant increase of the membrane resistance, the semi-IPNs demonstrated a reduction of the methanol permeability, comparing to the native Nafion. And the maximum power density of AMPS60 increased as much as 22.2% compared with Nafion

A self-supported 40W direct methanol fuel cell system

Indian Academy of Sciences (India)

... and maintains a constant methanol-feed concentration with thermal management in the system. ... During the operation, methanol ... catalyst poisoning.5–8 Accordingly, it is necessary to consider the operational characteristics of all the con-.

Improved Cathode Structure for a Direct Methanol Fuel Cell

Science.gov (United States)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been

Low methanol-permeable polyaniline/Nafion composite membrane for direct methanol fuel cells

Czech Academy of Sciences Publication Activity Database

Wang, C. H.; Chen, C. C.; Hsu, H. C.; Du, H. Y.; Chen, C. P.; Hwang, J. Y.; Chen, L. C.; Shih, H. C.; Stejskal, Jaroslav; Chen, K. H.

2009-01-01

Roč. 190, č. 2 (2009), s. 279-284 ISSN 0378-7753 R&D Projects: GA AV ČR IAA4050313 Institutional research plan: CEZ:AV0Z40500505 Keywords : DMFC * methanol crossover * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.792, year: 2009

High-performance alkaline direct methanol fuel cell using a nitrogen-postdoped anode.

Science.gov (United States)

Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Bender, Guido; O'Hayre, Ryan

2014-07-01

A commercial PtRu/C catalyst postdoped with nitrogen demonstrates a significantly higher performance (~10-20% improvement) in the anode of an alkaline direct methanol fuel cell than an unmodified commercial PtRu/C catalyst control. The enhanced performance shown herein is attributed at least partially to the increased electrochemical surface area of the PtRu/C after postdoping with nitrogen. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Anodic Flux and Temperature Controlling System for Micro Direct Methanol Fuel Cell

International Nuclear Information System (INIS)

Li, M M; Liu, C; Liang, J S; Wu, C B; Xu, Z

2006-01-01

Micro Direct Methanol Fuel Cell (μDMFC) is a kind of newly developed power sources, which effective apparatus for its performance evaluation is still in urgent need at present. In this study, a testing system was established for the purpose of testing the continuous working performance such as micro flux and temperature of μDMFC. In view of the temperature controlling for micro-flux liquid fuel, a heating block with labyrinth-like single pass channel inside for heating up the methanol solution was fabricated. A semiconductorrefrigerating chip was utilized to heat and cool the liquid flow during testing procedures. On the other hand, the two channels of a high accuracy double-channel syringe pump that can suck and pump in turn so as to transport methanol solution continuously was adopted. Based on the requirements of wide-ranged temperature and micro flux controlling, the solenoid valves and the correlative component were used. A hydraulic circuit, which can circulate the fed methanol cold to hot in turn, has also been constructed to test the fatigue life of the μDMFC. The automatic control was actualized by software module written with Visual C++. Experimental results show that the system is perfect in stability and it may provide an important and advanced evaluation apparatus to satisfy the needs for real time performance testing of μDMFC

A three-dimensional non-isothermal model for a membraneless direct methanol redox fuel cell

Science.gov (United States)

Wei, Lin; Yuan, Xianxia; Jiang, Fangming

2018-05-01

In the membraneless direct methanol redox fuel cell (DMRFC), three-dimensional electrodes contribute to the reduction of methanol crossover and the open separator design lowers the system cost and extends its service life. In order to better understand the mechanisms of this configuration and further optimize its performance, the development of a three-dimensional numerical model is reported in this work. The governing equations of the multi-physics field are solved based on computational fluid dynamics methodology, and the influence of the CO2 gas is taken into consideration through the effective diffusivities. The numerical results are in good agreement with experimental data, and the deviation observed for cases of large current density may be related to the single-phase assumption made. The three-dimensional electrode is found to be effective in controlling methanol crossover in its multi-layer structure, while it also increases the flow resistance for the discharging products. It is found that the current density distribution is affected by both the electronic conductivity and the concentration of reactants, and the temperature rise can be primarily attributed to the current density distribution. The sensitivity and reliability of the model are analyzed through the investigation of the effects of cell parameters, including porosity values of gas diffusion layers and catalyst layers, methanol concentration and CO2 volume fraction, on the polarization characteristics.

Preparation of supported PtRu/C electrocatalyst for direct methanol fuel cells

International Nuclear Information System (INIS)

Jiang Luhua; Sun Gongquan; Zhao Xinsheng; Zhou Zhenhua; Yan Shiyou; Tang Shuihua; Wang Guoxiong; Zhou Bing; Xin Qin

2005-01-01

In this work, high-surface supported PtRu/C were prepared with Ru(NO)(NO 3 ) 3 and [Pt(H 2 NCH 2 CH 2 NH 2 ) 2 ]Cl 2 as the precursors and hydrogen as a reducing agent. XRD and TEM analyses showed that the PtRu/C catalysts with different loadings possessed small and homogeneous metal particles. Even at high metal loading (40 wt.% Pt, 20 wt.% Ru) the mean metal particle size is less than 4 nm. Meanwhile, the calculated Pt crystalline lattice parameter and Pt (2 2 0) peak position indicated that the geometric structure of Pt was modified by Ru atoms. Among the prepared catalysts, the lattice parameter of 40-20 wt.% PtRu/C contract most. Cyclic voltammetry (CV), chronoamperometry (CA), CO stripping and single direct methanol fuel cell tests jointly suggested that the 40-20 wt.% PtRu/C catalyst has the highest electrochemical activity for methanol oxidation

Effect of fabrication and operating parameters on electrochemical property of anode and cathode for direct methanol fuel cells

International Nuclear Information System (INIS)

Liu, Guicheng; Zhou, Hongwei; Ding, Xianan; Li, Xinping; Zou, Dechun; Li, Xinyang; Wang, Xindong; Lee, Joong Kee

2016-01-01

Highlights: • A quick and simple method for optimizing assembly force of fuel cells. • Effect mechanisms of operating parameters on polarization of each electrode. • Working temperature is main factor to affect the optimal flow rates. • This paper is helpful to simulate the relation between operating parameters. - Abstract: A quick and simple method for optimizing assembly force of the direct methanol fuel cell has been introduced. Meanwhile, the effect mechanism of operating parameters on fuel cell performance and the properties of single anode and cathode have been intuitively investigated by a three-electrode system in this paper. The impedance curves indicate that internal resistance is the suitable intermediate to connect assembly torque and assembly force. The cathode polarization curve and limiting current density of methanol crossover are shown that the increasing methanol concentration markedly exacerbates the polarization in cathode due to serious methanol crossover phenomenon. Also, the higher cathode backpressure mainly improves cathode property, and lowers methanol crossover simultaneously. Finally, the summaries of peak power densities prove that the main factor that affected the optimal flow rates of methanol and oxygen is not the concentration or backpressure, but the working temperature.

Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Directory of Open Access Journals (Sweden)

Lei Xing

2011-01-01

Full Text Available An intrinsic time-dependent one-dimensional (1D model and a macro two-dimensional (2D model for the anode of the direct methanol fuel cell (DMFC are presented. The two models are based on the dual-site mechanism, which includes the coverage of intermediate species of methanol, OH, and CO (θM, θOH,Ru, and θCO,Pt on the surface of Pt and Ru. The intrinsic 1D model focused on the analysis of the effects of operating temperature, methanol concentration, and overpotential on the transient response. The macro 2D model emphasises the dimensionless distributions of methanol concentration, overpotential and current density in the catalyst layer which were affected by physical parameters such as thickness, specific area, and operating conditions such as temperature, bulk methanol concentration, and overpotential. The models were developed and solved in the PDEs module of COMSOL Multiphysics, giving good agreement with experimental data. The dimensionless distributions of methanol concentration, overpotential, and current density and the efficiency factor were calculated quantitatively. The models can be used to give accurate simulations for the polarisations of methanol fuel cell.

Cost Analysis of Direct Methanol Fuel Cell Stacks for Mass Production

Directory of Open Access Journals (Sweden)

Mauro Francesco Sgroi

2016-11-01

Full Text Available Fuel cells are very promising technologies for efficient electrical energy generation. The development of enhanced system components and new engineering solutions is fundamental for the large-scale deployment of these devices. Besides automotive and stationary applications, fuel cells can be widely used as auxiliary power units (APUs. The concept of a direct methanol fuel cell (DMFC is based on the direct feed of a methanol solution to the fuel cell anode, thus simplifying safety, delivery, and fuel distribution issues typical of conventional hydrogen-fed polymer electrolyte fuel cells (PEMFCs. In order to evaluate the feasibility of concrete application of DMFC devices, a cost analysis study was carried out in the present work. A 200 W-prototype developed in the framework of a European Project (DURAMET was selected as the model system. The DMFC stack had a modular structure allowing for a detailed evaluation of cost characteristics related to the specific components. A scale-down approach, focusing on the model device and projected to a mass production, was used. The data used in this analysis were obtained both from research laboratories and industry suppliers specialising in the manufacturing/production of specific stack components. This study demonstrates that mass production can give a concrete perspective for the large-scale diffusion of DMFCs as APUs. The results show that the cost derived for the DMFC stack is relatively close to that of competing technologies and that the introduction of innovative approaches can result in further cost savings.

Challenges in Design of an Orientation free Micro Direct Methanol Fuel Cell (µDMFC)

DEFF Research Database (Denmark)

Omidvarnia, Farzaneh; Hansen, Hans Nørgaard; Hales, Jan Harry

2014-01-01

the challenges in design and manufacturing of a micro direct methanol fuel cell (μDMFC) as the power generator in hearing aid devices is investigated. Among the different challenges in design for μDMFC, the CO2 bubble management and orientation independency of the cell are addressed by proposing a spring loaded...

Development of an electrode for direct methanol fuel cell

International Nuclear Information System (INIS)

Ramzia, A. M. S.; Iqbal, J.

2006-01-01

This paper presents the efficient use of platinum catalyst ruthenium with in the anode of a Direct Methanol Fuel Cell (DMFC). This is achieved by depositing platinum and ruthenium nano-particles on the pre-refluxed multi-walled carbon nano-tubes (MWCNT): MWCNTs were synthesized using the Chemical Vapor Deposition (CVD) with floating catalyst technique. The synthesized carbon nano tubes (CNT) were refluxed in 12M nitric acid to produce anchoring sites on the surface of the CNT. The platinum and ruthenium nano-particles were in a ratio of (3.1). These particles are deposited on the surface of the CNT at 60 wt % by reduction in ethylene glycol. Transmission micrograph (TEM) and scanning electron micrograph (SEM) images show the success of the deposition method. (author)

The Methanol Economy Project

Energy Technology Data Exchange (ETDEWEB)

Olah, George [Univ. of Southern California, Los Angeles, CA (United States); Prakash, G. K. [Univ. of Southern California, Los Angeles, CA (United States)

2014-02-01

The Methanol Economy Project is based on the concept of replacing fossil fuels with methanol generated either from renewable resources or abundant natural (shale) gas. The full methanol cycle was investigated in this project, from production of methanol through bromination of methane, bireforming of methane to syngas, CO₂ capture using supported amines, co-electrolysis of CO₂ and water to formate and syngas, decomposition of formate to CO₂ and H₂, and use of formic acid in a direct formic acid fuel cell. Each of these projects achieved milestones and provided new insights into their respective fields.

Micro-electro-mechanical systems (MEMS)-based micro-scale direct methanol fuel cell development

International Nuclear Information System (INIS)

Yao, S.-C.; Tang Xudong; Hsieh, C.-C.; Alyousef, Yousef; Vladimer, Michael; Fedder, Gary K.; Amon, Cristina H.

2006-01-01

This paper describes a high-power density, silicon-based micro-scale direct methanol fuel cell (DMFC), under development at Carnegie Mellon. Major issues in the DMFC design include the water management and energy-efficient micro fluidic sub-systems. The air flow and the methanol circulation are both at a natural draft, while a passive liquid-gas separator removes CO 2 from the methanol chamber. An effective approach for maximizing the DMFC energy density, pumping the excess water back to the anode, is illustrated. The proposed DMFC contains several unique features: a silicon wafer with arrays of etched holes selectively coated with a non-wetting agent for collecting water at the cathode; a silicon membrane micro pump for pumping the collected water back to the anode; and a passive liquid-gas separator for CO 2 removal. All of these silicon-based components are fabricated using micro-electro-mechanical systems (MEMS)-based processes on the same silicon wafer, so that interconnections are eliminated, and integration efforts as well as post-fabrication costs are both minimized. The resulting fuel cell has an overall size of one cubic inch, produces a net output of 10 mW, and has an energy density three to five times higher than that of current lithium-ion batteries

Self-assembled platinum nanoparticles on sulfonic acid-grafted graphene as effective electrocatalysts for methanol oxidation in direct methanol fuel cells.

Science.gov (United States)

Lu, Jinlin; Li, Yanhong; Li, Shengli; Jiang, San Ping

2016-02-15

In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs.

Compact Fuel-Cell System Would Consume Neat Methanol

Science.gov (United States)

Narayanan, Sekharipuram; Kindler, Andrew; Valdez, Thomas

2007-01-01

In a proposed direct methanol fuel-cell electric-power-generating system, the fuel cells would consume neat methanol, in contradistinction to the dilute aqueous methanol solutions consumed in prior direct methanol fuel-cell systems. The design concept of the proposed fuel-cell system takes advantage of (1) electro-osmotic drag and diffusion processes to manage the flows of hydrogen and water between the anode and the cathode and (2) evaporative cooling for regulating temperature. The design concept provides for supplying enough water to the anodes to enable the use of neat methanol while ensuring conservation of water for the whole fuel-cell system.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Liu, Gen [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Pan, Zhanchang, E-mail: panzhanchang@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Li, Wuyi; Yu, Ke [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Xia, Guowei; Zhao, Qixiang; Shi, Shikun [Victory Giant Technology (Hui Zhou) Co., Ltd., Huizhou 516083 (China); Hu, Guanghui; Xiao, Chumin; Wei, Zhigang [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China)

2017-07-15

Highlights: • TiNiN/CNT-rGO support with an interactive three-dimensional structure and high surface area was synthesized. • Pt nanoparticles with small size were well dispersed on TiNiN/CNT-rGO support. • Pt/TiNiN/CNT-rGO shows remarkably enhanced methanol oxidation activity and durability. - Abstract: Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

International Nuclear Information System (INIS)

Liu, Gen; Pan, Zhanchang; Li, Wuyi; Yu, Ke; Xia, Guowei; Zhao, Qixiang; Shi, Shikun; Hu, Guanghui; Xiao, Chumin; Wei, Zhigang

2017-01-01

Highlights: • TiNiN/CNT-rGO support with an interactive three-dimensional structure and high surface area was synthesized. • Pt nanoparticles with small size were well dispersed on TiNiN/CNT-rGO support. • Pt/TiNiN/CNT-rGO shows remarkably enhanced methanol oxidation activity and durability. - Abstract: Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

Characteristics of a direct methanol fuel cell system with the time shared fuel supplying approach

International Nuclear Information System (INIS)

Na, Youngseung; Kwon, Jungmin; Kim, Hyun; Cho, Hyejung; Song, Inseob

2013-01-01

DMFC (direct methanol fuel cell) systems usually employ two pumps for supplying the methanol solution. The conventional system configuration, however, may bring about free flow from the methanol reservoir and malfunctions in the self-priming of the pumps. When instruments such as check valves and pressure regulators are applied, they result in excessive weight and control system malfunctions. In this paper, a light and robust DMFC system is proposed. By using the time sharing approach to supply fuel with a 3-way valve, free flow does not occur because only one inlet is opened at one time which means that both the circulation flow from gas liquid separator and the fuel flow from the methanol cartridge are not allowed to be opened at same time. As a result, back flow and self-priming problems do not occur. This makes the system stable and robust due to the removal of both the check valves and the fluctuation from unstable back pressure. Stabilized system doesn't need excessive battery buffering and recycling water any more, which are responsible for the heavy system. The proposed system performs the same level of power and efficiency with the conventional system. Adaptability is also carried out in various environmental temperature conditions. - Highlights: ►A light and robust DMFC system is proposed. ► The circulation pump is able to self-prime by itself after long term storage. ► The time sharing approach to supply fuel enables to control the methanol concentration precisely. ► The methanol concentration is controlled without free flow and the back flow from the fuel feeding pump. ► The excessive buffer of the batteries and the recycling water level are reduced

Pt-Fe catalyst nanoparticles supported on single-wall carbon nanotubes: Direct synthesis and electrochemical performance for methanol oxidation

Science.gov (United States)

Ma, Xiaohui; Luo, Liqiang; Zhu, Limei; Yu, Liming; Sheng, Leimei; An, Kang; Ando, Yoshinori; Zhao, Xinluo

2013-11-01

Single-wall carbon nanotubes (SWCNTs) supported Pt-Fe nanoparticles have been prepared by one-step hydrogen arc discharge evaporation of carbon electrode containing both Pt and Fe metal elements. The formation of SWCNTs and Pt-Fe nanoparticles occur simultaneously during the evaporation process. High-temperature hydrogen treatment and hydrochloric acid soaking have been carried out to purify and activate those materials in order to obtain a new type of Pt-Fe/SWCNTs catalyst for methanol oxidation. The Pt-Fe/SWCNTs catalyst performs much higher electrocatalytic activity for methanol oxidation, better stability and better durability than a commercial Pt/C catalyst according to the electrochemical measurements, indicating that it has a great potential for applications in direct methanol fuel cells.

Combinatorial approach toward high-throughput analysis of direct methanol fuel cells.

Science.gov (United States)

Jiang, Rongzhong; Rong, Charles; Chu, Deryn

2005-01-01

A 40-member array of direct methanol fuel cells (with stationary fuel and convective air supplies) was generated by electrically connecting the fuel cells in series. High-throughput analysis of these fuel cells was realized by fast screening of voltages between the two terminals of a fuel cell at constant current discharge. A large number of voltage-current curves (200) were obtained by screening the voltages through multiple small-current steps. Gaussian distribution was used to statistically analyze the large number of experimental data. The standard deviation (sigma) of voltages of these fuel cells increased linearly with discharge current. The voltage-current curves at various fuel concentrations were simulated with an empirical equation of voltage versus current and a linear equation of sigma versus current. The simulated voltage-current curves fitted the experimental data well. With increasing methanol concentration from 0.5 to 4.0 M, the Tafel slope of the voltage-current curves (at sigma=0.0), changed from 28 to 91 mV.dec-1, the cell resistance from 2.91 to 0.18 Omega, and the power output from 3 to 18 mW.cm-2.

Single wall carbon nanotube supports for portable direct methanol fuel cells.

Science.gov (United States)

Girishkumar, G; Hall, Timothy D; Vinodgopal, K; Kamat, Prashant V

2006-01-12

Single-wall and multiwall carbon nanotubes are employed as carbon supports in direct methanol fuel cells (DMFC). The morphology and electrochemical activity of single-wall and multiwall carbon nanotubes obtained from different sources have been examined to probe the influence of carbon support on the overall performance of DMFC. The improved activity of the Pt-Ru catalyst dispersed on carbon nanotubes toward methanol oxidation is reflected as a shift in the onset potential and a lower charge transfer resistance at the electrode/electrolyte interface. The evaluation of carbon supports in a passive air breathing DMFC indicates that the observed power density depends on the nature and source of carbon nanostructures. The intrinsic property of the nanotubes, dispersion of the electrocatalyst and the electrochemically active surface area collectively influence the performance of the membrane electrode assembly (MEA). As compared to the commercial carbon black support, single wall carbon nanotubes when employed as the support for anchoring the electrocatalyst particles in the anode and cathode sides of MEA exhibited a approximately 30% enhancement in the power density of a single stack DMFC operating at 70 degrees C.

Energy efficiency of a direct-injection internal combustion engine with high-pressure methanol steam reforming

International Nuclear Information System (INIS)

Poran, Arnon; Tartakovsky, Leonid

2015-01-01

This article discusses the concept of a direct-injection ICE (internal combustion engine) with thermo-chemical recuperation realized through SRM (steam reforming of methanol). It is shown that the energy required to compress the reformate gas prior to its injection into the cylinder is substantial and has to be accounted for. Results of the analysis prove that the method of reformate direct-injection is unviable when the reforming is carried-out under atmospheric pressure. To reduce the energy penalty resulted from the gas compression, it is suggested to implement a high-pressure reforming process. Effects of the injection timing and the injector's flow area on the ICE-SRM system's fuel conversion efficiency are studied. The significance of cooling the reforming products prior to their injection into the engine-cylinder is demonstrated. We show that a direct-injection ICE with high-pressure SRM is feasible and provides a potential for significant efficiency improvement. Development of injectors with greater flow area shall contribute to further efficiency improvements. - Highlights: • Energy needed to compress the reformate is substantial and has to be accounted for. • Reformate direct-injection is unviable if reforming is done at atmospheric pressure. • Direct-injection engine with high-pressure methanol reforming is feasible. • Efficiency improvement by 12–14% compared with a gasoline-fed engine was shown

Controlled disulfonated poly(arylene ether sulfone) multiblock copolymers for direct methanol fuel cells.

Science.gov (United States)

Li, Qing; Chen, Yu; Rowlett, Jarrett R; McGrath, James E; Mack, Nathan H; Kim, Yu Seung

2014-04-23

Structure-property-performance relationships of disulfonated poly(arylene ether sulfone) multiblock copolymer membranes were investigated for their use in direct methanol fuel cell (DMFC) applications. Multiple series of reactive polysulfone, polyketone, and polynitrile hydrophobic block segments having different block lengths and molecular composition were synthesized and reacted with a disulfonated poly(arylene ether sulfone) hydrophilic block segment by a coupling reaction. Large-scale morphological order of the multiblock copolymers evolved with the increase of block size that gave notable influence on mechanical toughness, water uptake, and proton/methanol transport. Chemical structural changes of the hydrophobic blocks through polar group, fluorination, and bisphenol type allowed further control of the specific properties. DMFC performance was analyzed to elicit the impact of structural variations of the multiblock copolymers. Finally, DMFC performances of selected multiblock copolymers were compared against that of the industrial standard Nafion in the DMFC system.

Investigation of nano Pt and Pt-based alloys electrocatalysts for direct methanol fuel cells and their properties

Directory of Open Access Journals (Sweden)

Chunguang Suo

2014-03-01

Full Text Available The electrocatalysts used in micro direct methanol fuel cell (μDMFC, such as Pt/C and Pt alloy/C, prepared by liquid-phase NaBH4 reduction method have been investigated. XC-72 (Cobalt corp. Company, U.S.A is chosen as the activated carrier for the electrocatalysts to keep the catalysts powder in the range of several nanometers. The XRD, SEM, EDX analyses indicated that the catalysts had small particle size in several nanometers, in excellent dispersed phase and the molar ratio of the precious metals was found to be optimal. The performances of the DMFCs using cathodic catalyst with Pt percentage of 30wt% and different anodic catalysts (Pt-Ru, Pt-Ru-Mo were tested. The polarization curves and power density curves of the cells were measured to determine the optimal alloy composition and condition for the electrocatalysts. The results showed that the micro direct methanol fuel cell with 30wt% Pt/C as the cathodic catalyst and n(Pt:n(Ru:n(Mo = 3:2:2 PtRuMo/C as the anodic catalyst at room temperature using 2.0mol/L methanol solution has the best performances.

High methanol oxidation activity of electrocatalysts supported by directly grown nitrogen-containing carbon nanotubes on carbon cloth

International Nuclear Information System (INIS)

Wang, C.-H.; Shih, H.-C.; Tsai, Y.-T.; Du, H.-Y.; Chen, L.-C.; Chen, K.-H.

2006-01-01

The microstructure and electrochemical activity of the Pt-Ru supported by nitrogen-containing carbon nanotubes (CN x NTs) directly grown on the carbon cloth have been investigated. The CN x NTs directly grown on the carbon cloth (CN x NTs-carbon cloth composite electrode) were synthesized using microwave-plasma-enhanced chemical vapour deposition first and then use as the template to support the Pt-Ru nanoclusters subsequently sputtered on. The ferricyanide/ferrocyanide redox reaction in cyclic voltammetry (CV) measurements showed a faster electron transfer on the CN x NTs-carbon cloth composite electrode than the one with carbon cloth alone. Comparing their methanol oxidation abilities, it is found that the Pt-Ru nanoclusters supported by the CN x NTs-carbon cloth composite electrode have considerably higher electrocatalytic activity than the carbon cloth counterpart. This result suggests high performance of the CN x NTs-carbon cloth composite electrode, and demonstrates its suitability for direct methanol fuel cell applications

High methanol oxidation activity of electrocatalysts supported by directly grown nitrogen-containing carbon nanotubes on carbon cloth

Energy Technology Data Exchange (ETDEWEB)

Wang, C.-H. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Shih, H.-C. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Institue of Materials Science and Nano Technology, Chinese Culture University, Taipei, Taiwan (China); Tsai, Y.-T. [Institue of Materials Science and Nano Technology, Chinese Culture University, Taipei, Taiwan (China); Du, H.-Y. [Institue of Materials Science and Nano Technology, Chinese Culture University, Taipei, Taiwan (China); Chen, L.-C. [Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan (China); Chen, K.-H. [Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan (China) and Institue of Atomic and Molecular Science, Academia Sinica, Taipei, Taiwan (China)]. E-mail: chenkh@pub.iams.sinica.edu.tw

2006-12-01

The microstructure and electrochemical activity of the Pt-Ru supported by nitrogen-containing carbon nanotubes (CN {sub x} NTs) directly grown on the carbon cloth have been investigated. The CN {sub x} NTs directly grown on the carbon cloth (CN {sub x} NTs-carbon cloth composite electrode) were synthesized using microwave-plasma-enhanced chemical vapour deposition first and then use as the template to support the Pt-Ru nanoclusters subsequently sputtered on. The ferricyanide/ferrocyanide redox reaction in cyclic voltammetry (CV) measurements showed a faster electron transfer on the CN {sub x} NTs-carbon cloth composite electrode than the one with carbon cloth alone. Comparing their methanol oxidation abilities, it is found that the Pt-Ru nanoclusters supported by the CN {sub x} NTs-carbon cloth composite electrode have considerably higher electrocatalytic activity than the carbon cloth counterpart. This result suggests high performance of the CN {sub x} NTs-carbon cloth composite electrode, and demonstrates its suitability for direct methanol fuel cell applications.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

Science.gov (United States)

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

2015-12-04

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ 3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

The performance analysis of direct methanol fuel cells with different hydrophobic anode channels

Science.gov (United States)

Yeh, Hung-Chun; Yang, Ruey-Jen; Luo, Win-Jet; Jiang, Jia-You; Kuan, Yean-Der; Lin, Xin-Quan

In order to enhance the performance of the direct methanol fuel cell (DMFC), the product of CO 2 bubble has to be efficiently removed from the anode channel during the electrochemical reaction. In this study, the materials of Polymethyl Methacrylate (PMMA) with hydrophilic property and polydimethylsiloxane (PDMS) with hydrophobic property are used to form the anode cannel. The channel is fabricated through a microelectromechanical system (MEMS) manufacture process of the DMFCs. In addition, some particles with high hydrophobic properties are added into the PDMS materials in order to further reduce the hydro-resistance in the anode channel. The performance of the DMFCs is investigated under the influence of operation conditions, including operation temperature, flow rate, and methanol concentration. It is found that the performance of the DMFC, which is made of PDMS with high hydrophobic particles, can be greatly enhanced and the hydrophobic property of the particles can be unaffected by different operation conditions.

Methanol May Function as a Cross-Kingdom Signal

Science.gov (United States)

Dorokhov, Yuri L.; Komarova, Tatiana V.; Petrunia, Igor V.; Kosorukov, Vyacheslav S.; Zinovkin, Roman A.; Shindyapina, Anastasia V.; Frolova, Olga Y.; Gleba, Yuri Y.

2012-01-01

Recently, we demonstrated that leaf wounding results in the synthesis of pectin methylesterase (PME), which causes the plant to release methanol into the air. Methanol emitted by a wounded plant increases the accumulation of methanol-inducible gene mRNA and enhances antibacterial resistance as well as cell-to-cell communication, which facilitates virus spreading in neighboring plants. We concluded that methanol is a signaling molecule involved in within-plant and plant-to-plant communication. Methanol is considered to be a poison in humans because of the alcohol dehydrogenase (ADH)-mediated conversion of methanol into toxic formaldehyde. However, recent data showed that methanol is a natural compound in normal, healthy humans. These data call into question whether human methanol is a metabolic waste product or whether methanol has specific function in humans. Here, to reveal human methanol-responsive genes (MRGs), we used suppression subtractive hybridization cDNA libraries of HeLa cells lacking ADH and exposed to methanol. This design allowed us to exclude genes involved in formaldehyde and formic acid detoxification from our analysis. We identified MRGs and revealed a correlation between increases in methanol content in the plasma and changes in human leukocyte MRG mRNA levels after fresh salad consumption by volunteers. Subsequently, we showed that the methanol generated by the pectin/PME complex in the gastrointestinal tract of mice induces the up- and downregulation of brain MRG mRNA. We used an adapted Y-maze to measure the locomotor behavior of the mice while breathing wounded plant vapors in two-choice assays. We showed that mice prefer the odor of methanol to other plant volatiles and that methanol changed MRG mRNA accumulation in the mouse brain. We hypothesize that the methanol emitted by wounded plants may have a role in plant-animal signaling. The known positive effect of plant food intake on human health suggests a role for physiological methanol in

Design, fabrication and testing of an air-breathing micro direct methanol fuel cell with compound anode flow field

International Nuclear Information System (INIS)

Wang, Luwen; Zhang, Yufeng; Zhao, Youran; An, Zijiang; Zhou, Zhiping; Liu, Xiaowei

2011-01-01

An air-breathing micro direct methanol fuel cell (μDMFC) with a compound anode flow field structure (composed of the parallel flow field and the perforated flow field) is designed, fabricated and tested. To better analyze the effect of the compound anode flow field on the mass transfer of methanol, the compound flow field with different open ratios (ratio of exposure area to total area) and thicknesses of current collectors is modeled and simulated. Micro process technologies are employed to fabricate the end plates and current collectors. The performances of the μDMFC with a compound anode flow field are measured under various operating parameters. Both the modeled and the experimental results show that, comparing the conventional parallel flow field, the compound one can enhance the mass transfer resistance of methanol from the flow field to the anode diffusion layer. The results also indicate that the μDMFC with an anode open ratio of 40% and a thickness of 300 µm has the optimal performance under the 7 M methanol which is three to four times higher than conventional flow fields. Finally, a 2 h stability test of the μDMFC is performed with a methanol concentration of 7 M and a flow velocity of 0.1 ml min −1 . The results indicate that the μDMFC can work steadily with high methanol concentration.

Nano-Engineered Catalysts for Direct Methanol Fuel Cells

Science.gov (United States)

Myung, Nosang; Narayanan, Sekharipuram; Wiberg, Dean

2008-01-01

Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity. The present method involves electrodeposition of one or more catalytic metal(s) or a catalytic-metal/polytetrafluoroethylene nanocomposite on an alumina nanotemplate. The alumina nanotemplate is then dissolved, leaving the desired metal or metal/polytetrafluoroethylene-composite catalyst layer. Unlike some prior methods of making fine metal catalysts, this method does not involve processing at elevated temperature; all processing can be done at room temperature. In addition, this method involves fewer steps and is more amenable to scaling up for mass production. Alumina nanotemplates are porous alumina membranes that have been fabricated, variously, by anodizing either pure aluminum or aluminum that has been deposited on silicon by electronbeam evaporation. The diameters of the pores (7 to 300 nm), areal densities of pores (as much as 7 x 10(exp 10)sq cm), and lengths of pores (up to about 100 nm) can be tailored by selection of fabrication conditions. In a given case, the catalytic metal, catalytic metal alloy, or catalytic metal/ polytetrafluoroethylene composite is electrodeposited in the pores of the alumina nanotemplate. The dimensions of the pores, together with the electrodeposition conditions

Self-assembled platinum nanoparticles on sulfonic acid-grafted graphene as effective electrocatalysts for methanol oxidation in direct methanol fuel cells

Science.gov (United States)

Lu, Jinlin; Li, Yanhong; Li, Shengli; Jiang, San Ping

2016-02-01

In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs.

A “4-cell” modular passive DMFC (direct methanol fuel cell) stack for portable applications

International Nuclear Information System (INIS)

Wang, Luwen; He, Mingyan; Hu, Yue; Zhang, Yufeng; Liu, Xiaowei; Wang, Gaofeng

2015-01-01

A “4-cell” modular passive DMFC (direct methanol fuel cell) stack, which can be freely combined and applied to various electronic devices, is designed, fabricated and tested. Two PCB (printed circuit board) based accessories are designed and fabricated for electrically connecting and mechanically assembling the “4-cell” modules. The maximum power density of the “4-cell” module is 27 mW cm −2 at 5 M methanol concentration. The steady-state performances of the modular stacks with different numbers of modules are tested. The extra power loss of the multiple module stacks due to inter-module electrical connections is predicted by mathematical fitting method. The fitting results indicate that the efficiencies of the multiple module stacks are all above 90% up to 10 modules. The dynamic performances of the modular stacks are also investigated for portable applications. The results show that the modular stacks exhibit good responsiveness and reproducibility at high loading current (>100 mA). Finally, the modular stacks are successfully applied to drive the experimental fan and charge the mobile phone. - Highlights: • A “4-cell” modular passive DMFC (direct methanol fuel cell) stack is designed, fabricated and tested. • This modular DMFC stack can assemble more single cells with high efficiency. • The modular stack exhibit good responsiveness and reproducibility for portable application

Application of polythiophene to methanol vapor detection: an ab initio study.

Science.gov (United States)

Shokuhi Rad, Ali

2015-11-01

The interaction of methanol with terthiophene (3PT; a model of polythiophene) was investigated using density functional theory (DFT) at the BLYP-D3/6-31+G(d,p) level of theory. The computed density of states (DOS) pointed to considerable orbital hybridization upon the interaction of methanol with 3PT. Natural population analysis (NPA) was used to determine the charge distribution as well as the net charge transfer within the 3PT-methanol system, and thus to assess the sensing ability of terthiophene. The computed dipole moment revealed that the dielectric μ D changes upon the interaction of methanol with 3PT. Using calculated changes in the HOMO-LUMO energy gap, it was deduced that the electronic properties of 3PT are sensitive to the interaction of 3PT with methanol. After full energy relaxation, the interaction energy of methanol with 3PT in the most stable configuration was calculated to be -16.4 (counterpoise-corrected energy: -13.5) kJ mol(-1), providing proof that methanol is physisorbed by 3PT. Graphical Abstract Adsorption of methanol on polythiophene.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

Science.gov (United States)

Liu, Gen; Pan, Zhanchang; Li, Wuyi; Yu, Ke; Xia, Guowei; Zhao, Qixiang; Shi, Shikun; Hu, Guanghui; Xiao, Chumin; Wei, Zhigang

2017-07-01

Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

The electrolyte challenge for a direct methanol-air polymer electrolyte fuel cell operating at temperatures up to 200 C

Science.gov (United States)

Savinell, Robert; Yeager, Ernest; Tryk, Donald; Landau, Uziel; Wainright, Jesse; Gervasio, Dominic; Cahan, Boris; Litt, Morton; Rogers, Charles; Scherson, Daniel

1993-01-01

Novel polymer electrolytes are being evaluated for use in a direct methanol-air fuel cell operating at temperatures in excess of 100 C. The evaluation includes tests of thermal stability, ionic conductivity, and vapor transport characteristics. The preliminary results obtained to date indicate that a high temperature polymer electrolyte fuel cell is feasible. For example, Nafion 117 when equilibrated with phosphoric acid has a conductivity of at least 0.4 Omega(exp -1)cm(exp -1) at temperatures up to 200 C in the presence of 400 torr of water vapor and methanol vapor cross over equivalent to 1 mA/cm(exp 2) under a one atmosphere methanol pressure differential at 135 C. Novel polymers are also showing similar encouraging results. The flexibility to modify and optimize the properties by custom synthesis of these novel polymers presents an exciting opportunity to develop an efficient and compact methanol fuel cell.

Tuning of size and shape of Au–Pt nanocatalysts for direct methanol fuel cells

International Nuclear Information System (INIS)

Hunyadi Murph, Simona E.; Murphy, Catherine J.; Colon-Mercado, Hector R.; Torres, Ricardo D.; Heroux, Katie J.; Fox, Elise B.; Thompson, Lucas B.; Haasch, Richard T.

2011-01-01

In this article, we report the precise control of the size, shape, and surface morphology of Au–Pt nanocatalysts (cubes, blocks, octahedrons, and dogbones) synthesized via a seed-mediated approach. Gold “seeds” of different aspect ratios (1–4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au–Pt nanocatalysts at a low temperature (40 °C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis, UV–Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was employed to evaluate the Au–Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction of direct methanol fuel cells. The results indicate the Au–Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au–Pt dogbones and Pt-black; however, its performance is affected by the presence of MeOH.

TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS

Energy Technology Data Exchange (ETDEWEB)

Murph, S.

2011-04-20

In this paper, we report the precise control of the size, shape and surface morphology of Au-Pt nanocatalysts (cubes, blocks, octahedrons and dogbones) synthesized via a seed-mediated approach. Gold 'seeds' of different aspect ratios (1 to 4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au-Pt nanocatalysts at a low temperature (40 C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis (EDX), UV-Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was used to evaluate the Au-Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) of direct methanol fuel cells. The results indicate the Au-Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au-Pt dogbones and Pt-black, however its performance is affected by the presence of MeOH.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

Directory of Open Access Journals (Sweden)

Hyung Kyu Kim

2015-12-01

Full Text Available This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES proton exchange membranes (PEMs for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa and low water swelling (λ < 15 even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

A battery-fuel cell hybrid auxiliary power unit for trucks: Analysis of direct and indirect hybrid configurations

International Nuclear Information System (INIS)

Samsun, Remzi Can; Krupp, Carsten; Baltzer, Sidney; Gnörich, Bruno; Peters, Ralf; Stolten, Detlef

2016-01-01

Highlights: • A battery-fuel cell hybrid auxiliary power unit for heavy duty vehicles is reported. • Comparison of direct and indirect hybrids using representative load profiles. • Evaluation based on validated fuel cell system and battery models. • Indirect hybrid with constant fuel cell load yields 29.3% hybrid system efficiency. • Fuel cell should be pre-heated using waste heat from the diesel engine during drive. - Abstract: The idling operation of engines in heavy duty vehicles to cover electricity demand during layovers entails significant fuel consumption and corresponding emissions. Indeed, this mode of operation is highly inefficient and a noteworthy contributor to the transportation sector’s aggregate carbon dioxide emissions. Here, a potential solution to this wasteful practice is outlined in the form of a hybrid battery-fuel cell system for application as an auxiliary power unit for trucks. Drawing on experimentally-validated fuel cell and battery models, several possible hybrid concepts are evaluated and direct and indirect hybrid configurations analyzed using a representative load profile. The results indicate that a direct hybrid configuration is only applicable if the load demand profile does not deviate strongly from the assumed profile. Operation of an indirect hybrid with a constant fuel cell load yields the greatest hybrid system efficiency, at 29.3%, while battery size could be reduced by 87% if the fuel cell is operated at the highest dynamics. Maximum efficiency in truck applications can be achieved by pre-heating the system prior to operation using exhaust heat from the motor, which increased system efficiency from 25.3% to 28.1%, including start-up. These findings confirm that hybrid systems could offer enormous fuel savings and constitute a sizeable step on the path toward energy-efficient and environmentally-friendly heavy duty vehicles that does not necessitate a fuel switch.

Fabrication and Characterization of Chitosan Nanoparticle-Incorporated Quaternized Poly(Vinyl Alcohol) Composite Membranes as Solid Electrolytes for Direct Methanol Alkaline Fuel Cells

International Nuclear Information System (INIS)

Li, Pin-Chieh; Liao, Guan–Ming; Kumar, S. Rajesh; Shih, Chao-Ming; Yang, Chun-Chen; Wang, Da-Ming; Lue, Shingjiang Jessie

2016-01-01

Highlights: • Preparation of chitosan nanoparticles from bulk to enhance the degree of deacetylation. • The incorporation of chitosan nanoparticles into a QPVA matrix to form a nanocomposite membrane. • The nanocomposite constructed into thin-film membranes using the solution casting method. • To improve permeability, glutaraldehyde was cross-linked with the nanocomposite membranes. • A direct methanol alkaline fuel cell was studied at different temperatures. - Abstract: In this study, we designed a method for the preparation of chitosan nanoparticles incorporated into a quaternized poly(vinyl alcohol) (QPVA) matrix for direct methanol alkaline fuel cells (DMAFCs). The structural and morphological properties of the prepared nanocomposites were studied using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM) and dynamic laser-light scattering (DLS). The crystallinity of the nanocomposite solid electrolytes containing 0 and 10% chitosan nanoparticles were investigated using differential scanning calorimetry (DSC). The electrochemical measurement of resulting nanocomposite membranes were analyzed according to the following parameters: methanol permeability, liquid uptakes, ionic conductivity and cell performances. The composite membranes with 10% chitosan nanoparticles in a QPVA matrix (CQPVA) show suppressed methanol permeability and higher ionic conductivity than pristine QPVA. In addition, the glutaraldehyde cross-linked nanocomposite film exhibited improvement on the methanol barrier property at 80 °C. The peak power density of the DMAFCs reached 67 mW cm −2 when fed into 1 M of methanol in 6 M of KOH.

Investigation of methanol oxidation on a highly active and stable Pt–Sn electrocatalyst supported on carbon–polyaniline composite for application in a passive direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Amani, Mitra [Department of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Kazemeini, Mohammad [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Hamedanian, Mahboobeh [Department of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Pahlavanzadeh, Hassan [Department of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Gharibi, Hussein, E-mail: h.gharibi@utah.edu [Department of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Department of Material Science & Engineering, 122 S Campus Drive, University of Utah, Salt Lake City, UT 84112 (United States)

2015-08-15

Highlights: • PtSn/C-PANI performed superior in the MOR compared with a commercial PtRu/C. • Catalytic activity of PtRu/C was highly reduced during the accelerated durability test. • Anode of the PtSn/C-PANI in a passive DMFC lowered methanol crossover by 30%. - Abstract: Polyaniline fiber (PANI) was synthesized and utilized to fabricate a vulcan–polyaniline (C-PANI) composite. Pt/C-PANI and PtSn/C-PANI electro-catalysts with different Pt:Sn atomic ratios were prepared by the impregnation method. These electro-catalysts, along with commercial PtRu/C (Electrochem), were characterized with respect to their structural and electrochemical properties in methanol oxidation reaction (MOR). PtSn(70:30)/C-PANI showed excellent performance in MOR, the obtained maximum current density being about 40% and 50% higher than that for PtRu/C and Pt/C-PANI, respectively. It was also found that the CO tolerance and stability of PtSn(70:30)/C-PANI was considerably higher than that of PtRu/C. Finally, the performance of these two materials was compared in a passive direct methanol fuel cell (DMFC). The DMFC test results demonstrated that the membrane electrode assembly (MEA) prepared using PtSn(70:30)/C-PANI anode catalyst performed more satisfactorily in terms of maximum power density and lower methanol crossover.

Metabolism of methanol in acetogenic bacteria

International Nuclear Information System (INIS)

Ivey, D.K.W.

1987-01-01

Acetogens can grown on methanol in the presence of a cosubstrate that is more oxidized than methanol. Three mol of acetate is formed from 4 mol methanol and 2 mol CO 2 . One mol of methanol is oxidized to CO 2 . The levels of the tetrahydrofolate enzymes, carbon monoxide dehydrogenase, and corrinoids indicate the presence of the acetyl CoA pathway when growing on methanol. The acetyl-CoA pathway of acetate synthesis as presently understood does not include methanol as a substrate. It is demonstrated that methanol is oxidized to formaldehyde and then to formate by a methanol dehydrogenase. It is also possible that the methyl group of methanol is transferred directly to either a corrinoid-type enzyme, or tetrahydrofolate. When cells of C. thermoautotrophicum are grown on 14 CO 2 , acetate becomes labeled in both carbons with a ratio 14 CH 3 / 14 COOH of 0.7. In addition, methanol gets labeled. When cells are grown on 14 CH 3 OH, label appears in both acetate carbons with a ratio of 3.3, and also appears in CO 2 . Thus methanol is preferentially incorporated into the methyl group of acetate, whereas CO 2 is the preferred source of the carboxyl carbon

Investigation of Ruthenium Dissolution in Advanced Membrane Electrode Assemblies for Direct Methanol Based Fuel Cells Stacks

Science.gov (United States)

Valdez, T. I.; Firdosy, S.; Koel, B. E.; Narayanan, S. R.

2005-01-01

This viewgraph presentation gives a detailed review of the Direct Methanol Based Fuel Cell (DMFC) stack and investigates the Ruthenium that was found at the exit of the stack. The topics include: 1) Motivation; 2) Pathways for Cell Degradation; 3) Cell Duration Testing; 4) Duration Testing, MEA Analysis; and 5) Stack Degradation Analysis.

SHAPE SELECTIVE NANO-CATALYSTS: TOWARD DIRECT METHANOL FUEL CELLS APPLICATIONS

Energy Technology Data Exchange (ETDEWEB)

Murph, S.

2010-06-16

A series of bimetallic core-shell-alloy type Au-Pt nanomaterials with various morphologies, aspect ratios and compositions, were produced in a heterogenous epitaxial fashion. Gold nanoparticles with well-controlled particle size and shape, e.g. spheres, rods and cubes, were used as 'seeds' for platinum growth in the presence of a mild reducing agent, ascorbic acid and a cationic surfactant cethyltrimethyl ammonium bromide (CTAB). The reactions take place in air and water, and are quick, economical and amenable for scaling up. The synthesized nanocatalysts were characterized by electron microscopy techniques and energy dispersive X-ray analysis. Nafion membranes were embedded with the Au-Pt nanomaterials and analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) for their potential in direct methanol fuel cells applications.

Direct electrical arc ignition of hybrid rocket motors

Science.gov (United States)

Judson, Michael I., Jr.

Hybrid rockets motors provide distinct safety advantages when compared to traditional liquid or solid propellant systems, due to the inherent stability and relative inertness of the propellants prior to established combustion. As a result of this inherent propellant stability, hybrid motors have historically proven difficult to ignite. State of the art hybrid igniter designs continue to require solid or liquid reactants distinct from the main propellants. These ignition methods however, reintroduce to the hybrid propulsion system the safety and complexity disadvantages associated with traditional liquid or solid propellants. The results of this study demonstrate the feasibility of a novel direct electrostatic arc ignition method for hybrid motors. A series of small prototype stand-alone thrusters demonstrating this technology were successfully designed and tested using Acrylonitrile Butadiene Styrene (ABS) plastic and Gaseous Oxygen (GOX) as propellants. Measurements of input voltage and current demonstrated that arc-ignition will occur using as little as 10 watts peak power and less than 5 joules total energy. The motor developed for the stand-alone small thruster was adapted as a gas generator to ignite a medium-scale hybrid rocket motor using nitrous oxide /and HTPB as propellants. Multiple consecutive ignitions were performed. A large data set as well as a collection of development `lessons learned' were compiled to guide future development and research. Since the completion of this original groundwork research, the concept has been developed into a reliable, operational igniter system for a 75mm hybrid motor using both gaseous oxygen and liquid nitrous oxide as oxidizers. A development map of the direct spark ignition concept is presented showing the flow of key lessons learned between this original work and later follow on development.

Mass-produced multi-walled carbon nanotubes as catalyst supports for direct methanol fuel cells.

Science.gov (United States)

Jang, In Young; Park, Ki Chul; Jung, Yong Chae; Lee, Sun Hyung; Song, Sung Moo; Muramatsu, Hiroyuki; Kim, Yong Jung; Endo, Morinobu

2011-01-01

Commercially mass-produced multi-walled carbon nanotubes, i.e., VGNF (Showa Denko Co.), were applied to support materials for platinum-ruthenium (PtRu) nanoparticles as anode catalysts for direct methanol fuel cells. The original VGNFs are composed of high-crystalline graphitic shells, which hinder the favorable surface deposition of the PtRu nanoparticles that are formed via borohydride reduction. The chemical treatment of VGNFs with potassium hydroxide (KOH), however, enables highly dispersed and dense deposition of PtRu nanoparticles on the VGNF surface. This capability becomes more remarkable depending on the KOH amount. The electrochemical evaluation of the PtRu-deposited VGNF catalysts showed enhanced active surface areas and methanol oxidation, due to the high dispersion and dense deposition of the PtRu nanoparticles. The improvement of the surface deposition states of the PtRu nanoparticles was significantly due to the high surface area and mesorporous surface structure of the KOH-activated VGNFs.

Development of an air-breathing direct methanol fuel cell with the cathode shutter current collectors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yufeng; Liu, Xiaowei [Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, Harbin 150001 (China); MEMS Center, Harbin Institute of Technology, Harbin 150001 (China); Zhang, Peng; Zhang, Bo; Li, Jianmin; Deng, Huichao [MEMS Center, Harbin Institute of Technology, Harbin 150001 (China)

2010-06-15

An air-breathing direct methanol fuel cell with a novel cathode shutter current collector is fabricated to develop the power sources for consumer electronic devices. Compared with the conventional circular cathode current collector, the shutter one improves the oxygen consumption and mass transport. The anode and cathode current collectors are made of stainless steel using thermal stamping die process. Moreover, an encapsulation method using the tailor-made clamps is designed to assemble the current collectors and MEA for distributing the stress of the edges and inside uniformly. It is observed that the maximum power density of the air-breathing DMFC operating with 1 M methanol solution achieves 19.7 mW/cm{sup 2} at room temperature. Based on the individual DMFCs, the air-breathing stack consisting of 36 DMFC units is achieved and applied to power a notebook computer. (author)

Experimental study on methanol recovery through flashing vaporation in continuous production of biodiesel via supercritical methanol

International Nuclear Information System (INIS)

Wang Cunwen; Chen Wen; Wang Weiguo; Wu Yuanxin; Chi Ruan; Tang Zhengjiao

2011-01-01

To improve the oil conversion, high methanol/oil molar ratio is required in the continuous production of biodiesel via supercritical methanol transesterification in tubular reactor. And thus the subsequent excess methanol recovery needs high energy consumption. Based on the feature of high temperature and high pressure in supercritical methanol transesterification, excess methanol recovery in reaction system by flashing vaporation is conducted and the effect of reaction temperature, reaction pressure and flashing pressure on methanol recovery and methanol concentration in gas phase is discussed in detail in this article. Results show that at the reaction pressure of 9-15 MPa and the reaction temperature of 240-300 o C, flashing pressure has significant influence on methanol recovery and methanol content in gas phase, which can be effectively improved by reducing flashing pressure. At the same time, reaction temperature and reaction pressure also have an important effect on methanol recovery and methanol content in gas phase. At volume flow of biodiesel and methanol 1:2, tubular reactor pressure 15 MPa, tubular reactor temperature 300 o C and the flashing pressure 0.4 MPa, methanol recovery is more than 85% and methanol concentration of gas phase (mass fraction) is close to 99% after adiabatic braising; therefore, the condensate liquid of gas phase can be injected directly into methanol feedstock tank to be recycled. Research abstracts: Biodiesel is an important alternative energy, and supercritical methanol transesterification is a new and green technology to prepare biodiesel with some obvious advantages. But it also exists some problems: high reaction temperature, high reaction pressure and large molar ratio of methanol/oil will cause large energy consumption which restricts supercritical methanol for the industrial application of biodiesel. So a set of tubular reactor-coupled flashing apparatus is established for continuous preparing biodiesel in supercritical

Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol–methanol mixtures

Energy Technology Data Exchange (ETDEWEB)

Martinez-Guerra, Edith; Gude, Veera Gnaneswar, E-mail: gude@cee.msstate.edu

2014-12-15

Highlights: • Pulse sonication effect on transesterification of waste vegetable oil was studied. • Effects of ethanol, methanol, and alcohol mixtures on FAMEs yield were evaluated. • Effect of ultrasonic intensity, power density, and its output rates were evaluated. • Alcohol mixtures resulted in higher biodiesel yields due to better solubility. - Abstract: This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol–methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol–methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1–2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol–methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.

Enhanced activity of Pt/CNTs anode catalyst for direct methanol fuel cells using Ni2P as co-catalyst

Science.gov (United States)

Li, Xiang; Luo, Lanping; Peng, Feng; Wang, Hongjuan; Yu, Hao

2018-03-01

The direct methanol fuel cell is a promising energy conversion device because of the utilization of the state-of-the-art platinum (Pt) anode catalyst. In this work, novel Pt/Ni2P/CNTs catalysts were prepared by the H2 reduction method. It was found that the activity and stability of Pt for methanol oxidation reaction (MOR) could be significantly enhanced while using nickel phosphide (Ni2P) nanoparticles as co-catalyst. X-ray photoelectron spectroscopy revealed that the existence of Ni2P affected the particle size and electronic distribution of Pt obviously. Pt/CNTs catalyst, Pt/Ni2P/CNTs catalysts with different Ni2P amount were synthesized, among which Pt/6%Ni2P/CNTs catalyst exhibited the best MOR activity of 1400 mAmg-1Pt, which was almost 2.5 times of the commercial Pt/C-JM catalyst. Moreover, compared to other Pt-based catalysts, this novel Pt/Ni2P/CNTs catalyst also exhibited higher onset current density and better steady current density. The result of this work may provide positive guidance to the research on high efficiency and stability of Pt-based catalyst for direct methanol fuel cells.

The influence of methanol on the chemical state of PtRu anodes in a high-temperature direct methanol fuel cell studied in situ by synchrotron-based near-ambient pressure x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Saveleva, Viktoriia A; Savinova, Elena R; Daletou, Maria K

2017-01-01

Synchrotron radiation-based near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) has recently become a powerful tool for the investigation of interfacial phenomena in electrochemical power sources such as batteries and fuel cells. Here we present an in situ NAP-XPS study of the anode of a high-temperature direct methanol fuel cell with a phosphoric acid-doped hydrocarbon membrane, which reveals an enhanced flooding of the Pt 3 Ru anode with phosphoric acid in the presence of methanol. An analysis of the electrode surface composition depending on the cell voltage and on the presence of methanol reveals the strong influence of the latter on the extent of Pt oxidation and on the transformation of Ru into Ru (IV) hydroxide. (paper)

The influence of methanol on the chemical state of PtRu anodes in a high-temperature direct methanol fuel cell studied in situ by synchrotron-based near-ambient pressure x-ray photoelectron spectroscopy

Science.gov (United States)

Saveleva, Viktoriia A.; Daletou, Maria K.; Savinova, Elena R.

2017-01-01

Synchrotron radiation-based near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) has recently become a powerful tool for the investigation of interfacial phenomena in electrochemical power sources such as batteries and fuel cells. Here we present an in situ NAP-XPS study of the anode of a high-temperature direct methanol fuel cell with a phosphoric acid-doped hydrocarbon membrane, which reveals an enhanced flooding of the Pt3Ru anode with phosphoric acid in the presence of methanol. An analysis of the electrode surface composition depending on the cell voltage and on the presence of methanol reveals the strong influence of the latter on the extent of Pt oxidation and on the transformation of Ru into Ru (IV) hydroxide.

Real-time monitoring of methanol concentration using a shear horizontal surface acoustic wave sensor for direct methanol fuel cell without reference liquid measurement

Science.gov (United States)

Tada, Kyosuke; Nozawa, Takuya; Kondoh, Jun

2017-07-01

In recent years, there has been an increasing demand for sensors that continuously measure liquid concentrations and detect abnormalities in liquid environments. In this study, a shear horizontal surface acoustic wave (SH-SAW) sensor is applied for the continuous monitoring of liquid concentrations. As the SH-SAW sensor functions using the relative measurement method, it normally needs a reference at each measurement. However, if the sensor is installed in a liquid flow cell, it is difficult to measure a reference liquid. Therefore, it is important to establish an estimation method for liquid concentrations using the SH-SAW sensor without requiring a reference measurement. In this study, the SH-SAW sensor is installed in a direct methanol fuel cell to monitor the methanol concentration. The estimated concentration is compared with a conventional density meter. Moreover, the effect of formic acid is examined. When the fuel temperature is higher than 70 °C, it is necessary to consider the influence of liquid conductivity. Here, an estimation method for these cases is also proposed.

A two step method to synthesize palladium-copper nanoparticles on reduced graphene oxide and their extremely high electrocatalytic activity for the electrooxidation of methanol and ethanol

Science.gov (United States)

Na, HeYa; Zhang, Lei; Qiu, HaiXia; Wu, Tao; Chen, MingXi; Yang, Nian; Li, LingZhi; Xing, FuBao; Gao, JianPing

2015-08-01

Palladium-copper nanoparticles (Pd-Cu NPs) supported on reduced graphene oxide (RGO) with different Pd/Cu ratios (Pd-Cu/RGO) were prepared by a two step method. The Pd-Cu/RGO hybrids were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and thermogravimetric analyses. Cyclic voltammetry and chronoamperometry were used to investigate the electrochemical activities and stabilities of the Pd-Cu/RGO catalysts for the electro-oxidation of methanol and ethanol in alkaline media. The Pd-Cu/RGO catalysts exhibited high catalytic activities and good stabilities. This is because the catalysts have a bimetallic structure consisting of a small Pd-Cu core surrounded by a thin Pd-rich shell which improves the catalytic activities of the Pd-Cu/RGO hybrids. Thus they should be useful in direct methanol and ethanol fuel cells.

Increasing the operation temperature of polymer electrolyte membranes for fuel cells: From nanocomposites to hybrids

Science.gov (United States)

Licoccia, Silvia; Traversa, Enrico

Among the possible systems investigated for energy production with low environmental impact, polymeric electrolyte membrane fuel cells (PEMFCs) are very promising as electrochemical power sources for application in portable technology and electric vehicles. For practical applications, operating FCs at temperatures above 100 °C is desired, both for hydrogen and methanol fuelled cells. When hydrogen is used as fuel, an increase of the cell temperature produces enhanced CO tolerance, faster reaction kinetics, easier water management and reduced heat exchanger requirement. The use of methanol instead of hydrogen as a fuel for vehicles has several practical benefits such as easy transport and storage, but the slow oxidation kinetics of methanol needs operating direct methanol fuel cells (DMFCs) at intermediate temperatures. For this reason, new membranes are required. Our strategy to achieve the goal of operating at temperatures above 120 °C is to develop organic/inorganic hybrid membranes. The first approach was the use of nanocomposite class I hybrids where nanocrystalline ceramic oxides were added to Nafion. Nanocomposite membranes showed enhanced characteristics, hence allowing their operation up to 130 °C when the cell was fuelled with hydrogen and up to 145 °C in DMFCs, reaching power densities of 350 mW cm -2. The second approach was to prepare Class II hybrids via the formation of covalent bonds between totally aromatic polymers and inorganic clusters. The properties of such covalent hybrids can be modulated by modifying the ratio between organic and inorganic groups and the nature of the chemical components allowing to reach high and stable conductivity values up to 6.4 × 10 -2 S cm -1 at 120 °C.

Diamond nanoparticles as a support for Pt and PtRu catalysts for direct methanol fuel cells.

Science.gov (United States)

La-Torre-Riveros, Lyda; Guzman-Blas, Rolando; Méndez-Torres, Adrián E; Prelas, Mark; Tryk, Donald A; Cabrera, Carlos R

2012-02-01

Diamond in nanoparticle form is a promising material that can be used as a robust and chemically stable catalyst support in fuel cells. It has been studied and characterized physically and electrochemically, in its thin film and powder forms, as reported in the literature. In the present work, the electrochemical properties of undoped and boron-doped diamond nanoparticle electrodes, fabricated using the ink-paste method, were investigated. Methanol oxidation experiments were carried out in both half-cell and full fuel cell modes. Platinum and ruthenium nanoparticles were chemically deposited on undoped and boron doped diamond nanoparticles through the use of NaBH(4) as reducing agent and sodium dodecyl benzene sulfonate (SDBS) as a surfactant. Before and after the reduction process, samples were characterized by electron microscopy and spectroscopic techniques. The ink-paste method was also used to prepare the membrane electrode assembly with Pt and Pt-Ru modified undoped and boron-doped diamond nanoparticle catalytic systems, to perform the electrochemical experiments in a direct methanol fuel cell system. The results obtained demonstrate that diamond supported catalyst nanomaterials are promising for methanol fuel cells.

Recycling of greenhouse gases via methanol

Energy Technology Data Exchange (ETDEWEB)

Bill, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Eliasson, B; Kogelschatz, U [ABB Corporate Research Center, Baden-Daettwil (Switzerland)

1997-06-01

Greenhouse gas emissions to the atmosphere can be mitigated by using direct control technologies (capture, disposal or chemical recycling). We report on carbon dioxide and methane recycling with other chemicals, especially with hydrogen and oxygen, to methanol. Methanol synthesis from CO{sub 2} is investigated on various catalysts at moderate pressures ({<=}30 bar) and temperatures ({<=}300{sup o}C). The catalysts show good methanol activities and selectivities. The conversion of CO{sub 2} and CH{sub 4} to methanol is also studied in a silent electrical discharge at pressures of 1 to 4 bar and temperatures close to room temperature. Methanol yields are given for mixtures of CO{sub 2}/H{sub 2}, CH{sub 4}/O{sub 2} and also for CH{sub 4} and air mixtures. (author) 2 figs., 5 refs.

Increasing Fuel Efficiency of Direct Methanol Fuel Cell Systems with Feedforward Control of the Operating Concentration

Directory of Open Access Journals (Sweden)

Youngseung Na

2015-09-01

Full Text Available Most of the R&D on fuel cells for portable applications concentrates on increasing efficiencies and energy densities to compete with other energy storage devices, especially batteries. To improve the efficiency of direct methanol fuel cell (DMFC systems, several modifications to system layouts and operating strategies are considered in this paper, rather than modifications to the fuel cell itself. Two modified DMFC systems are presented, one with an additional inline mixer and a further modification of it with a separate tank to recover condensed water. The set point for methanol concentration control in the solution is determined by fuel efficiency and varies with the current and other process variables. Feedforward concentration control enables variable concentration for dynamic loads. Simulation results were validated experimentally with fuel cell systems.

Application of green chemistry techniques to prepare electrocatalysts for direct methanol fuel cells.

Science.gov (United States)

Shimizu, Kenichi; Wang, Joanna S; Wai, Chien M

2010-03-25

A series of green techniques for synthesizing carbon nanotube-supported platinum nanoparticles and their high electrocatalytic activity toward methanol fuel cell applications are reported. The techniques utilize either the supercritical fluid carbon dioxide or water as a medium for depositing platinum nanoparticles on surfaces of multiwalled or single-walled carbon nanotubes. The catalytic properties of the carbon nanotubes-supported Pt nanoparticle catalysts prepared by four different techniques are compared for anodic oxidation of methanol and cathodic reduction of oxygen using cyclic voltammetry. One technique using galvanic exchange of Pt(2+) in water with zerovalent iron present on the surfaces of as-grown single-walled carbon nanotubes produces a Pt catalyst that shows an unusually high catalytic activity for reduction of oxygen but a negligible activity for oxidation of methanol. This fuel-selective catalyst may have a unique application as a cathode catalyst in methanol fuel cells to alleviate the problems caused by crossover of methanol through the polymer electrolyte membrane.

New catalysts for miniaturized methanol fuel cells

DEFF Research Database (Denmark)

Pedersen, Christoffer Mølleskov

The methanol fuel cell is an interesting energy technology, capable of converting the chemical energy of methanol directly into electricity. The technology is specifically attractive for small mobile applications such as laptops, smartphones, tablets etc. since it offers almost instantaneously...

Performance of an Active Micro Direct Methanol Fuel Cell Using Reduced Catalyst Loading MEAs

Directory of Open Access Journals (Sweden)

D.S. Falcão

2017-10-01

Full Text Available The micro direct methanol fuel cell (MicroDMFC is an emergent technology due to its special interest for portable applications. This work presents the results of a set of experiments conducted at room temperature using an active metallic MicroDMFC with an active area of 2.25 cm2. The MicroDMFC uses available commercial materials with low platinum content in order to reduce the overall fuel cell cost. The main goal of this work is to provide useful information to easily design an active MicroDMFC with a good performance recurring to cheaper commercial Membrane Electrode Assemblies MEAs. A performance/cost analysis for each MEA tested is provided. The maximum power output obtained was 18.1 mW/cm2 for a hot-pressed MEA with materials purchased from Quintech with very low catalyst loading (3 mg/cm2 Pt–Ru at anode side and 0.5 mg/cm2 PtB at the cathode side costing around 15 euros. Similar power values are reported in literature for the same type of micro fuel cells working at higher operating temperatures and substantially higher cathode catalyst loadings. Experimental studies using metallic active micro direct methanol fuel cells operating at room temperature are very scarce. The results presented in this work are, therefore, very useful for the scientific community.

Development of a Direct Methanol Fuel Cell with Lightweight Disc Type Current Collectors

Directory of Open Access Journals (Sweden)

Yean-Der Kuan

2014-05-01

Full Text Available The direct methanol fuel cell (DMFC adopts methanol solution as a fuel suitable for low power portable applications. A miniature, lightweight, passive air-breathing design is therefore desired. This paper presents a novel planar disc-type DMFC with multiple cells containing a novel developed lightweight current collector at both the anode and cathode sides. The present lightweight current collector adopts FR4 Glass/Epoxy as the substrate with the current collecting areas located at the corresponding membrane electrolyte assembly (MEA areas. The current collecting areas are fabricated by sequentially coating a corrosion resistant layer and electrical conduction layer via the thermal evaporation technique. The anode current collector has carved flow channels for fuel transport and production. The cathode current collector has drilled holes for passive air breathing. In order to ensure feasibility in the present concept a 3-cell prototype DMFC module with lightweight disc type current collectors is designed and constructed. Experiments were conducted to measure the cell performance. The results show that the highest cell power output is 54.88 mW·cm−2 and successfully demonstrate the feasibility of this novel design.

Dimensionally stable Nafion-polyethylene composite membranes for direct methanol fuel cell applications

NARCIS (Netherlands)

Yildirim, M.H.; Stamatialis, Dimitrios; Wessling, Matthias

2008-01-01

Nafion ® impregnated Solupor ®, microporous UHMWPE film, (N-PE), Nafion ®117 (N117) and a membrane prepared using a DE2020 Nafion ® dispersion (DE2020) were characterized with respect to their swelling degree (SD), methanol cross-over, proton conductivity and DMFC performance at various methanol

Photocatalytic conversion of methane to methanol

Energy Technology Data Exchange (ETDEWEB)

Taylor, C.E.; Noceti, R.P.; D`Este, J.R. [Pittsburgh Energy Technology Center, PA (United States)

1995-12-31

A long-term goal of our research group is the exploration of novel pathways for the direct oxidation of methane to liquid fuels, chemicals, and intermediates. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. The products of reaction, methanol and hydrogen, are both commercially desirable, methanol being used as is or converted to a variety of other chemicals, and the hydrogen could be utilized in petroleum and/or chemical manufacturing. Methane is produced as a by-product of coal gasification. Depending upon reactor design and operating conditions, up to 18% of total gasifier product may be methane. In addition, there are vast proven reserves of geologic methane in the world. Unfortunately, a large fraction of these reserves are in regions where there is little local demand for methane and it is not economically feasible to transport it to a market. There is a global research effort under way in academia, industry, and government to find methods to convert methane to useful, more readily transportable and storable materials. Methanol, the initial product of methane oxidation, is a desirable product of conversion because it retains much of the original energy of the methane while satisfying transportation and storage requirements. Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of the current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol, is attractive. Research in the laboratory is directed toward applying the techniques developed for the photocatalytic splitting of the water and the photochemical conversion of methane.

Methanol Oxidation on Model Elemental and Bimetallic Transition Metal Surfaces

DEFF Research Database (Denmark)

Tritsaris, G. A.; Rossmeisl, J.

2012-01-01

Direct methanol fuel cells are a key enabling technology for clean energy conversion. Using density functional theory calculations, we study the methanol oxidation reaction on model electrodes. We discuss trends in reactivity for a set of monometallic and bimetallic transition metal surfaces, flat...... sites on the surface and to screen for novel bimetallic surfaces of enhanced activity. We suggest platinum copper surfaces as promising anode catalysts for direct methanol fuel cells....

Self-Healing Proton-Exchange Membranes Composed of Nafion-Poly(vinyl alcohol) Complexes for Durable Direct Methanol Fuel Cells.

Science.gov (United States)

Li, Yixuan; Liang, Liang; Liu, Changpeng; Li, Yang; Xing, Wei; Sun, Junqi

2018-04-30

Proton-exchange membranes (PEMs) that can heal mechanical damage to restore original functions are important for the fabrication of durable and reliable direct methanol fuel cells (DMFCs). The fabrication of healable PEMs that exhibit satisfactory mechanical stability, enhanced proton conductivity, and suppressed methanol permeability via hydrogen-bonding complexation between Nafion and poly(vinyl alcohol) (PVA) followed by postmodification with 4-carboxybenzaldehyde (CBA) molecules is presented. Compared with pure Nafion, the CBA/Nafion-PVA membranes exhibit enhanced mechanical properties with an ultimate tensile strength of ≈20.3 MPa and strain of ≈380%. The CBA/Nafion-PVA membrane shows a proton conductivity of 0.11 S cm -1 at 80 °C, which is 1.2-fold higher than that of a Nafion membrane. The incorporated PVA gives the CBA/Nafion-PVA membranes excellent proton conductivity and methanol resistance. The resulting CBA/Nafion-PVA membranes are capable of healing mechanical damage of several tens of micrometers in size and restoring their original proton conductivity and methanol resistance under the working conditions of DMFCs. The healing property originates from the reversibility of hydrogen-bonding interactions between Nafion and CBA-modified PVA and the high chain mobility of Nafion and CBA-modified PVA. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bimetallic Nickel/Ruthenium Catalysts Synthesized by Atomic Layer Deposition for Low-Temperature Direct Methanol Solid Oxide Fuel Cells.

Science.gov (United States)

Jeong, Heonjae; Kim, Jun Woo; Park, Joonsuk; An, Jihwan; Lee, Tonghun; Prinz, Fritz B; Shim, Joon Hyung

2016-11-09

Nickel and ruthenium bimetallic catalysts were heterogeneously synthesized via atomic layer deposition (ALD) for use as the anode of direct methanol solid oxide fuel cells (DMSOFCs) operating in a low-temperature range. The presence of highly dispersed ALD Ru islands over a porous Ni mesh was confirmed, and the Ni/ALD Ru anode microstructure was observed. Fuel cell tests were conducted using Ni-only and Ni/ALD Ru anodes with approximately 350 μm thick gadolinium-doped ceria electrolytes and platinum cathodes. The performance of fuel cells was assessed using pure methanol at operating temperatures of 300-400 °C. Micromorphological changes of the anode after cell operation were investigated, and the content of adsorbed carbon on the anode side of the operated samples was measured. The difference in the maximum power density between samples utilizing Ni/ALD Ru and Pt/ALD Ru, the latter being the best catalyst for direct methanol fuel cells, was observed to be less than 7% at 300 °C and 30% at 350 °C. The improved electrochemical activity of the Ni/ALD Ru anode compared to that of the Ni-only anode, along with the reduction of the number of catalytically active sites due to agglomeration of Ni and carbon formation on the Ni surface as compared to Pt, explains this decent performance.

Triboluminescence and associated decomposition of solid methanol

International Nuclear Information System (INIS)

Trout, G.J.; Moore, D.E.; Hawke, J.G.

1975-01-01

The decomposition is initiated by the cooling of solid methanol through the β → α transiRon at 157.8K, producing the gases hydrogen, carbon monoxide, and methane. The passage through this lambda transition causes the breakup of large crystals of β-methanol into crystallites of α-methanol and is accompanied by light emission as well as decomposition. This triboluminescence is accompanied by, and apparently produced by, electrical discharges through methanol vapor in the vicinity of the solid. The potential differences needed to produce the electrical breakdown of the methanol vapor apparently arise from the disruption of the long hydrogen bonded chains of methanol molecules present in crystalline methanol. Charge separation following crystal deformation is a characteristic of substances which exhibit gas discharge triboluminescence; solid methanol has been found to emit such luminescence when mechanically deformed in the absence of the β → α transition The decomposition products are not produced directly by the breaking up of the solid methanol but from the vapor phase methanol by the electrical discharges. That gas phase decomposition does occur was confirmed by observing that the vapors of C 2 H 5 OH, CH 3 OD, and CD 3 OD decompose on being admitted to a vessel containing methanol undergoing the β → α phase transition. (U.S.)

Bio-refinery system in a pulp mill for methanol production with comparison of pressurized black liquor gasification and dry gasification using direct causticization

International Nuclear Information System (INIS)

Naqvi, Muhammad; Yan, Jinyue; Dahlquist, Erik

2012-01-01

Black liquor gasification (BLG) for bio-fuel or electricity production at the modern pulp mills is a field in continuous evolution and the efforts are considerably driven by the climate change, fuel security, and renewable energy. This paper evaluates and compares two BLG systems for methanol production: (i) oxygen blown pressurized thermal BLG; and (ii) dry BLG with direct causticization, which have been regarded as the most potential technology candidates for the future deployment. A key objective is to assess integration possibilities of BLG technologies with the reference Kraft pulp mill producing 1000 air dried tonnes (ADt) pulp/day replacing conventional recovery cycle. The study was performed to compare the systems’ performance in terms of potential methanol production, energy efficiency, and potential CO 2 reductions. The results indicate larger potential of black liquor conversion to methanol from the pressurized BLG system (about 77 million tonnes/year of methanol) than the dry BLG system (about 30 million tonnes/year of methanol) utilizing identical amount of black liquor available worldwide (220 million tDS/year). The potential CO 2 emissions reduction from the transport sector is substantially higher in pressurized BLG system (117 million tonnes/year CO 2 reductions) as compared to dry BLG system (45 million tonnes/year CO 2 reductions). However, the dry BLG system with direct causticization shows better results when considering consequences of additional biomass import. In addition, comparison of methanol production via BLG with other bio-refinery products, e.g. hydrogen, dimethyl ether (DME) and bio-methane, has also been discussed.

High thermal efficiency and low emission performance of a methanol reformed gas fueled engine for hybrid electric vehicles

Energy Technology Data Exchange (ETDEWEB)

Yamane, K.; Nakajima, Y.; Shudo, T.; Hiruma, M. [Musahi Inst. of Tech., Tokyo (Japan); Komatsu, H.; Takagi, Y. [Nissan Motor Co., Ltd., Yokosuka (Japan)

2000-07-01

An internal combustion engine (ICE) operation was carried out experimentally by using the mixture of air and fuel simulating the reformed gas as the fuel. It has been found that the engine can expectedly attain ultra-low emission and high thermal efficiency, namely 35% brake thermal efficiency in the basis of the low heat value of the theoretically reformed gas or 42% in the basis of the low heat value of methanol. By using the result for the estimation of the total thermal efficiency at the end of the motor output shaft of a hybrid electric vehicle, it has been found that the total thermal efficiency of the reformed gas engine system is 34% in case of a 120% energy increment and 33% in case of a 116% energy increment with a little higher NOx emission of 60 ppm while the counterpart of the fuel cell system is 34%. When the emission level for EZEV is required, the total thermal efficiency falls to 32% in case of a 120% energy increment and 31% in case of a 116% energy increment. From the points of the reliability proved by the long history, higher specific power and low cost, the internal combustion engine system with the thermal efficiency almost equal to that of the fuel cell (FC) system is further more practical when methanol is used as the fuel. (orig.)

Methanol as an energy carrier

Energy Technology Data Exchange (ETDEWEB)

Biedermann, P.; Grube, T.; Hoehlein, B. (eds.)

2006-07-01

For the future, a strongly growing energy demand is expected in the transport sector worldwide. Economically efficient oil production will run through a maximum in the next decade. Higher fuel prices and an environmentally desirable reduction of emissions will increase the pressure for reducing fuel consumption and emissions in road traffic. These criteria show the urgent necessity of structural changes in the fuel market. Due to its advantages concerning industrial-scale production, storage and global availability, methanol has the short- to medium-term potential for gaining increased significance as a substitution product in the energy market. Methanol can be produced both from fossil energy sources and from biomass or waste materials through the process steps of synthesis gas generation with subsequent methanol synthesis. Methanol has the potential to be used in an environmentally friendly manner in gasoline/methanol mixtures for flexible fuel vehicles with internal combustion engines and in diesel engines with pure methanol. Furthermore, it can be used in fuel cell vehicles with on-board hydrogen production in direct methanol fuel cell drives, and in stationary systems for electricity and heat generation as well as for hydrogen production. Finally, in portable applications it serves as an energy carrier for electric power generation. In this book, the processes for the production and use of methanol are presented and evaluated, markets and future options are discussed and issues of safety and environmental impacts are addressed by a team of well-known authors. (orig.)

A durable PtRu/C catalyst with a thin protective layer for direct methanol fuel cells.

Science.gov (United States)

Shimazaki, Yuzuru; Hayasaka, Sho; Koyama, Tsubasa; Nagao, Daisuke; Kobayashi, Yoshio; Konno, Mikio

2010-11-15

A methanol oxidation catalyst with improved durability in acidic environments is reported. The catalyst consists of PtRu alloy nanoparticles on a carbon support that were stabilized with a silane-coupling agent. The catalyst was prepared by reducing ions of Pt and Ru in the presence of a carbon support and the silane-coupling agent. The careful choice of preparatory conditions such as the concentration of the silane-coupling agent and solution pH resulted in the preparation of catalyst in which the PtRu nanoparticles were dispersively adsorbed onto the carbon support. The catalytic activity was similar to that of a commercial catalyst and was unchanged after immersion in sulfuric acid solution for 1000 h, suggesting the high durability of the PtRu catalyst for the anode of direct methanol fuel cells. Copyright © 2010 Elsevier Inc. All rights reserved.

A transient multi-scale model for direct methanol fuel cells

International Nuclear Information System (INIS)

Jahnke, T.; Zago, M.; Casalegno, A.; Bessler, W.G.; Latz, A.

2017-01-01

The DMFC is a promising option for backup power systems and for the power supply of portable devices. However, from the modeling point of view liquid-feed DMFC are challenging systems due to the complex electrochemistry, the inherent two-phase transport and the effect of methanol crossover. In this paper we present a physical 1D cell model to describe the relevant processes for DMFC performance ranging from electrochemistry on the surface of the catalyst up to transport on the cell level. A two-phase flow model is implemented describing the transport in gas diffusion layer and catalyst layer at the anode side. Electrochemistry is described by elementary steps for the reactions occurring at anode and cathode, including adsorbed intermediate species on the platinum and ruthenium surfaces. Furthermore, a detailed membrane model including methanol crossover is employed. The model is validated using polarization curves, methanol crossover measurements and impedance spectra. It permits to analyze both steady-state and transient behavior with a high level of predictive capabilities. Steady-state simulations are used to investigate the open circuit voltage as well as the overpotentials of anode, cathode and electrolyte. Finally, the transient behavior after current interruption is studied in detail.

Catalyst inks and method of application for direct methanol fuel cells

Science.gov (United States)

Zelenay, Piotr; Davey, John; Ren, Xiaoming; Gottesfeld, Shimshon; Thomas, Sharon C.

2004-02-24

Inks are formulated for forming anode and cathode catalyst layers and applied to anode and cathode sides of a membrane for a direct methanol fuel cell. The inks comprise a Pt catalyst for the cathode and a Pt--Ru catalyst for the anode, purified water in an amount 4 to 20 times that of the catalyst by weight, and a perfluorosulfonic acid ionomer in an amount effective to provide an ionomer content in the anode and cathode surfaces of 20% to 80% by volume. The inks are prepared in a two-step process while cooling and agitating the solutions. The final solution is placed in a cooler and continuously agitated while spraying the solution over the anode or cathode surface of the membrane as determined by the catalyst content.

Electrical enhancement of direct methanol fuel cells by metal-plasma ion implantation Pt-Ru/C multilayer catalysts.

Science.gov (United States)

Weng, Ko-Wei; Chen, Yung-Lin; Chen, Ya-Chi; Lin, Tai-Nan

2009-02-01

Direct methanol fuel cells (DMFC) have been widely studied owing to their simple cell configuration, high volume energy density, short start-up time, high operational reliability and other favorable characteristics. However, major limitations include high production cost, poisoning of the catalyst and methanol crossover. This study adopts a simple technique for preparing Pt-Ru/C multilayer catalysts, including magnetron sputtering (MS) and metal-plasma ion implantation (MPII). The Pt catalysts were sputtered onto the gas diffusion layer (GDL), followed by the implantation of Ru catalysts using MPII (at an accelerating voltage of 20 kV and an implantation dose of 1 x 10(16) ions/cm2). Pt-Ru is repeatedly processed to prepare Pt-Ru/C multilayer catalysts. The catalyst film structure and microstructure were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM), respectively. The cell performance was tested using a potential stat/galvano-stat. The results reveal that the membrane electrode assembly (MEA) of four multilayer structures enhances the cell performance of DMFC. The measured power density is 2.2 mW/cm2 at a methanol concentration of 2 M, with an OCV of 0.493 V.

On the effect of operating conditions in liquid-feed direct methanol fuel cells: A multiphysics modeling approach

International Nuclear Information System (INIS)

García-Salaberri, Pablo A.; Vera, Marcos

2016-01-01

A multiphysics model for liquid-feed Direct Methanol Fuel Cells is presented. The model accounts for two-dimensional (2D) across-the-channel anisotropic mass and charge transport in the anode and cathode Gas Diffusion Layers (GDLs), including the effect of GDL assembly compression and electrical contact resistances at the Bipolar Plate (BPP) and membrane interfaces. A one-dimensional (1D) across-the-membrane model is used to describe local species diffusion through the microporous layers, methanol/water crossover, proton transport, and electrochemical reactions, thereby coupling both GDL sub-models. The 2D/1D model is extended to the third dimension and supplemented with 1D descriptions of the flow channels to yield a 3D/1D + 1D model that is successfully validated. A parametric study is then conducted on the 2D/1D model to examine the effect of operating conditions on cell performance. The results show that an optimum methanol concentration exists that maximizes power output due to the trade-off between anode polarization and cathode mixed overpotential. For fixed methanol concentration, cell performance is largely affected by the oxygen supply rate, cell temperature, and liquid/gas saturation levels. There is also an optimal GDL compression due to the trade-off between ohmic and concentration losses, which strongly depends on BPP material and, more weakly, on the actual operating conditions. - Highlights: • A multiphysics model for liquid-feed DMFCs is presented. • GDL anisotropic transport, assembly compression, and ohmic contact resistances are considered. • The model is successfully validated against previous experimental data. • Optimum methanol concentrations, GDL compressions, and operating temperatures are reported. • Oxygen-starved conditions with spontaneous hydrogen evolution in the anode are also considered.

Performance evaluation of direct methanol fuel cells for portable applications

Energy Technology Data Exchange (ETDEWEB)

Rashidi, R.; Dincer, I.; Naterer, G.F. [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario (Canada); Berg, P. [Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario (Canada)

2009-02-15

This study examines the feasibility of powering a range of portable devices with a direct methanol fuel cell (DMFC). The analysis includes a comparison between a Li-ion battery and DMFC to supply the power for a laptop, camcorder and a cell phone. A parametric study of the systems for an operational period of 4 years is performed. Under the assumptions made for both the Li-ion battery and DMFC system, the battery cost is lower than the DMFC during the first year of operation. However, by the end of 4 years of operational time, the DMFC system would cost less. The weight and cost comparisons show that the fuel cell system occupies less space than the battery to store a higher amount of energy. The weight of both systems is almost identical. Finally, the CO{sub 2} emissions can be decreased by a higher exergetic efficiency of the DMFC, which leads to improved sustainability. (author)

Direct synthesis of iso-butane from synthesis gas or CO2 over CuZnZrAl/Pd-β hybrid catalyst

Directory of Open Access Journals (Sweden)

Congming Li

2017-12-01

Full Text Available The effect of various factors on the catalytic performance of iso-butane formation over CuZnZrAl/Pd-β hybrid catalyst via synthesis gas or CO2 hydrogenation has been deeply investigated in this work. It was interesting to note that the iso-butane/n-butane ratio value was much higher than that of thermodynamic equilibrium (about 1/1, whose value was directly related to the reaction condition using this hybrid catalyst. In order to further clearly clarify this finding, various experimental reaction factors were selected to investigate the formation of iso-butane. The results revealed that increasing temperature, H2/COx, CO2/COx, and/or Pd loading possessed an inhibiting effect on the iso-butane yield. High selectivity of iso-butane could be achieved by increasing the reaction pressure, W/F and the weight ratio of CuZnZrAl methanol catalyst to Pd-β catalyst. It is also noted that the addition of water seriously suppressed the reaction activity, resulting in the low ratio of iso-butane/n-butane. A possible reaction route was elucidated based on the latest results. This might shed light on the development of a high efficient catalyst for iso-butane production from synthesis gas or CO2 hydrogenation. Keywords: Iso-butane, Synthesis gas, CO2, CuZnZrAl/Pd-β hybrid catalyst

Ion pair reinforced semi-interpenetrating polymer network for direct methanol fuel cell applications.

Science.gov (United States)

Fang, Chunliu; Julius, David; Tay, Siok Wei; Hong, Liang; Lee, Jim Yang

2012-06-07

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.

Nafion–clay hybrids with a network structure

KAUST Repository

Burgaz, Engin; Lian, Huiqin; Alonso, Rafael Herrera; Estevez, Luis; Kelarakis, Antonios; Giannelis, Emmanuel P.

2009-01-01

Nafion-clay hybrid membranes with a unique microstructure were synthesized using a fundamentally new approach. The new approach is based on depletion aggregation of suspended particles - a well-known phenomenon in colloids. For certain concentrations of clay and polymer, addition of Nafion solution to clay suspensions in water leads to a gel. Using Cryo-TEM we show that the clay particles in the hybrid gels form a network structure with an average cell size in the order of 500 nm. The hybrid gels are subsequently cast to produce hybrid Nafion-clay membranes. Compared to pure Nafion the swelling of the hybrid membranes in water and methanol is dramatically reduced while their selectivity (ratio of conductivity over permeability) increases. The small decrease of ionic conductivity for the hybrid membranes is more than compensated by the large decrease in methanol permeability. Lastly the hybrid membranes are much stiffer and can withstand higher temperatures compared to pure Nafion. Both of these characteristics are highly desirable for use in fuel cell applications, since a) they will allow the use of a thinner membrane circumventing problems associated with the membrane resistance and b) enable high temperature applications. © 2009 Elsevier Ltd. All rights reserved.

Nafion–clay hybrids with a network structure

KAUST Repository

Burgaz, Engin

2009-05-01

Nafion-clay hybrid membranes with a unique microstructure were synthesized using a fundamentally new approach. The new approach is based on depletion aggregation of suspended particles - a well-known phenomenon in colloids. For certain concentrations of clay and polymer, addition of Nafion solution to clay suspensions in water leads to a gel. Using Cryo-TEM we show that the clay particles in the hybrid gels form a network structure with an average cell size in the order of 500 nm. The hybrid gels are subsequently cast to produce hybrid Nafion-clay membranes. Compared to pure Nafion the swelling of the hybrid membranes in water and methanol is dramatically reduced while their selectivity (ratio of conductivity over permeability) increases. The small decrease of ionic conductivity for the hybrid membranes is more than compensated by the large decrease in methanol permeability. Lastly the hybrid membranes are much stiffer and can withstand higher temperatures compared to pure Nafion. Both of these characteristics are highly desirable for use in fuel cell applications, since a) they will allow the use of a thinner membrane circumventing problems associated with the membrane resistance and b) enable high temperature applications. © 2009 Elsevier Ltd. All rights reserved.

Isolated Fe sites in Metal Organic Framework catalyze the direct conversion of methane to methanol

KAUST Repository

Osadchii, Dmitrii; Olivos Suarez, Alma Itzel; Szé csé nyi, Á gnes; Li, Guanna; Nasalevich, Maxim A.; Dugulan, A Iulian; Serra-Crespo, Pablo; Hensen, Emiel J. M.; Veber, Sergey L.; Fedin, Matvey V.; Sankar, Gopinathan; Pidko, Evgeny A; Gascon, Jorge

2018-01-01

Hybrid materials bearing organic and inorganic motives have been extensively discussed as playgrounds for the implementation of atomically resolved inorganic sites within a confined environment, with an exciting similarity to enzymes. Here, we present the successful design of a site-isolated mixed-metal Metal Organic Framework that mimics the reactivity of soluble methane monooxygenase enzyme reactivity and demonstrates the potential of this strategy to overcome current challenges in selective methane oxidation. We describe the synthesis and characterisation of an Fe-containing MOF that comprises the desired antiferromagnetically cou-pled high spin species in a coordination environment closely resembling that of the enzyme. An electrochemi-cal synthesis method is used to build the microporous MOF matrix while integrating, with an exquisite con-trol, the atomically dispersed Fe active sites in the crystalline scaffold. The model mimics the catalytic C-H activation behaviour of the enzyme to produce methanol, and shows that the key to this reactivity is the for-mation of isolated oxo-bridged Fe units.

Isolated Fe sites in Metal Organic Framework catalyze the direct conversion of methane to methanol

KAUST Repository

Osadchii, Dmitrii

2018-05-10

Hybrid materials bearing organic and inorganic motives have been extensively discussed as playgrounds for the implementation of atomically resolved inorganic sites within a confined environment, with an exciting similarity to enzymes. Here, we present the successful design of a site-isolated mixed-metal Metal Organic Framework that mimics the reactivity of soluble methane monooxygenase enzyme reactivity and demonstrates the potential of this strategy to overcome current challenges in selective methane oxidation. We describe the synthesis and characterisation of an Fe-containing MOF that comprises the desired antiferromagnetically cou-pled high spin species in a coordination environment closely resembling that of the enzyme. An electrochemi-cal synthesis method is used to build the microporous MOF matrix while integrating, with an exquisite con-trol, the atomically dispersed Fe active sites in the crystalline scaffold. The model mimics the catalytic C-H activation behaviour of the enzyme to produce methanol, and shows that the key to this reactivity is the for-mation of isolated oxo-bridged Fe units.

Direct methanol feed fuel cell and system

Science.gov (United States)

Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

2009-01-01

Improvements to non acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous. The fuel cell system also comprises a fuel supplying part including a meter which meters an amount of fuel which is used by the fuel cell, and controls the supply of fuel based on said metering.

Durability and efficiency tests for direct methanol fuel cell's long-term performance assessment

International Nuclear Information System (INIS)

Yeh, Pulin; Chang, Chu Hsiang; Shih, Naichien; Yeh, Naichia

2016-01-01

This research assessed the long-term performance of direct methanol fuel cells. The experiment was performed at room temperature using 0.51 mol/L ∼0.651 mol/L methanol with a fuel consumption rate of 0.8 ± 0.1 cc/Wh at stack temperature of 60 °C–70 °C. DuPont Nafion115 proton exchange membrane was used as the base material of MEA (membrane electrode assembly), which is then examined via a series of processes that include I−V curve test, humidity cycle test, load cycle test, and hydrogen penetration test. The study employs membrane modification and cell structure adjustment approaches to reduce the methanol crossover in the cathode and identify the cell performance effect of the carbon paper gas diffusion layer. The test results indicated an efficiency of 25% can be achieved with a three-piece MEA assembly. According to the durability test, the stack power-generation efficiency has maintained at 15%–25% level. With such efficiency, the stack voltage output has been able to stay above 7.8-V for over 5000 h. This result is in line with industry standard. - Highlights: • Assess DMFC performance under non-optimal conditions for production readiness. • Output of 26-cell DMFC stack stays beyond 7.8v after 5000 operation hours. • Power-generation efficiency of 26-cell DMFC stack maintains between 15%–20%.

A comparative study of approaches to direct methanol fuel cells modelling

Energy Technology Data Exchange (ETDEWEB)

Oliveira, V.B.; Falcao, D.S.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [Instituto Nacional de Engenharia, Tecnologia e Inovacao, Paco do Lumiar, 22,1649-038 (Portugal)

2007-03-15

Fuel cell modelling has received much attention over the past decade in an attempt to better understand the phenomena occurring within the cell. Mathematical models and simulation are needed as tools for design optimization of fuel cells, stacks and fuel cell power systems. Analytical, semi-empirical and mechanistic models for direct methanol fuel cells (DMFC) are reviewed. Effective models were until now developed describing the fundamental electrochemical and transport phenomena taking place in the cell. More research is required to develop models that can account for the two-phase flows occurring in the anode and cathode of the DMFC. The merits and demerits of the models are presented. Selected models of different categories are implemented and discussed. Finally, one of the selected simplified models is proposed as a computer-aided tool for real-time system level DMFC calculations. (author)

Characterization and fuel cell performance analysis of polyvinylalcohol-mordenite mixed-matrix membranes for direct methanol fuel cell use

Energy Technology Data Exchange (ETDEWEB)

Uctug, Fehmi Goerkem, E-mail: gorkem.uctug@bahcesehir.edu.t [University of Manchester, School of Chemical Engineering and Analytical Science, M60 1QD (United Kingdom); Holmes, Stuart M. [University of Manchester, School of Chemical Engineering and Analytical Science, M60 1QD (United Kingdom)

2011-10-01

Highlights: > We investigated the availability of PVA-mordenite membranes for DMFC use. > We measured the methanol permeability of PVA-mordenite membranes via pervaporation. > We did the fuel cell testing of these membranes, which had not been done before. > We showed that PVA-mordenite membranes have poorer DMFC performance than Nafion. > Membrane performance can be improved by increasing the proton conductivity of PVA. - Abstract: Polyvinylalcohol-mordenite (PVA-MOR) mixed matrix membranes were synthesized for direct methanol fuel cell (DMFC) use. For the structural and the morphological characterization, Scanning Electron Microscopy and Thermal Gravimetric Analysis methods were used. Zeolite distribution within the polymer matrix was found to be homogeneous. An impedance spectroscope was used to measure the proton conductivity. In order to obtain information about methanol permeation characteristics, swelling tests and a series of pervaporation experiments were carried out. 60-40 wt% PVA-MOR membranes were found to give the optimum transport properties. Proton conductivity of these membranes was found to be slightly lower than that of Nafion117{sup TM} whereas their methanol permeability was at least two orders of magnitude lower than Nafion117{sup TM}. DMFC performance of the PVA-MOR membranes was also measured. The inferior DMFC performance of PVA-MOR membranes was linked to drying in the fuel cell medium and the consequent proton conductivity loss. Their performance was improved by adding a dilute solution of sulfuric acid into the feed methanol solution. Future studies on the improvement of the proton conductivity of PVA-MOR membranes, especially via sulfonation of the polymer matrix, can overcome the low-performance problem associated with insufficient proton conductivity.

Characterization and fuel cell performance analysis of polyvinylalcohol-mordenite mixed-matrix membranes for direct methanol fuel cell use

International Nuclear Information System (INIS)

Uctug, Fehmi Goerkem; Holmes, Stuart M.

2011-01-01

Highlights: → We investigated the availability of PVA-mordenite membranes for DMFC use. → We measured the methanol permeability of PVA-mordenite membranes via pervaporation. → We did the fuel cell testing of these membranes, which had not been done before. → We showed that PVA-mordenite membranes have poorer DMFC performance than Nafion. → Membrane performance can be improved by increasing the proton conductivity of PVA. - Abstract: Polyvinylalcohol-mordenite (PVA-MOR) mixed matrix membranes were synthesized for direct methanol fuel cell (DMFC) use. For the structural and the morphological characterization, Scanning Electron Microscopy and Thermal Gravimetric Analysis methods were used. Zeolite distribution within the polymer matrix was found to be homogeneous. An impedance spectroscope was used to measure the proton conductivity. In order to obtain information about methanol permeation characteristics, swelling tests and a series of pervaporation experiments were carried out. 60-40 wt% PVA-MOR membranes were found to give the optimum transport properties. Proton conductivity of these membranes was found to be slightly lower than that of Nafion117 TM whereas their methanol permeability was at least two orders of magnitude lower than Nafion117 TM . DMFC performance of the PVA-MOR membranes was also measured. The inferior DMFC performance of PVA-MOR membranes was linked to drying in the fuel cell medium and the consequent proton conductivity loss. Their performance was improved by adding a dilute solution of sulfuric acid into the feed methanol solution. Future studies on the improvement of the proton conductivity of PVA-MOR membranes, especially via sulfonation of the polymer matrix, can overcome the low-performance problem associated with insufficient proton conductivity.

Highly stable ionic-covalent cross-linked sulfonated poly(ether ether ketone) for direct methanol fuel cells

Science.gov (United States)

Lei, Linfeng; Zhu, Xingye; Xu, Jianfeng; Qian, Huidong; Zou, Zhiqing; Yang, Hui

2017-05-01

A novel ionic cross-linked sulfonated poly(ether ether ketone) containing equal content of sulfonic acid and pendant tertiary amine groups (TA-SPEEK) has been initially synthesized for the application in direct methanol fuel cells (DMFCs). By adjusting the ratio of p-xylene dibromide to tertiary amine groups of TA-SPEEK, a series of ionic-covalent cross-linked membranes (C-SPEEK-x) with tunable degree of cross-linking are prepared. Compared with the pristine membrane, the ionic and ionic-covalent cross-linked proton exchange membranes (PEMs) exhibit reduced methanol permeability and improved mechanical properties, dimensional and oxidative stability. The proton conductivity and methanol selectivity of protonated TA-SPEEK and C-SPEEK-x at 25 °C is up to 0.109 S cm-1 and 3.88 × 105 S s cm-3, respectively, which are higher than that of Nafion 115. The DMFC incorporating C-SPEEK-25 exhibits a maximum power density as high as 35.3 mW cm-2 with 4 M MeOH at 25 °C (31.8 mW cm-2 for Nafion 115). Due to the highly oxidative stability of the membrane, no obvious performance degradation of the DMFC is observed after more than 400 h operation, indicating such cost-effective ionic-covalent cross-linked membranes have substantial potential as alternative PEMs for DMFC applications.

Highly dispersed Pt-Ni nanoparticles on nitrogen-doped carbon nanotubes for application in direct methanol fuel cells.

Science.gov (United States)

Jiang, Shujuan; Ma, Yanwen; Tao, Haisheng; Jian, Guoqiang; Wang, Xizhang; Fan, Yining; Zhu, Jianmin; Hu, Zheng

2010-06-01

Binary Pt-Ni alloyed nanoparticles supported on nitrogen-doped carbon nanotubes (NCNTs) have been facilely constructed without pre-modification by making use of the active sites in NCNTs due to the N-participation. So-obtained binary Pt-Ni alloyed nanoparticles have been highly dispersed on the outer surface of the support with the size of about 3-4 nm. The electrochemical properties of the catalysts for methanol oxidation have been systematically evaluated. Binary Pt-Ni alloyed composites with molar ratio (Pt:Ni) of 3:2 and 3:1 present enhanced electrocatalytic activities and improved tolerance to CO poisoning as well as the similar stability, in comparison with the commercial Pt/C catalyst and the monometallic Pt/NCNTs catalysts. These results imply that so-constructed nanocomposite catalysts have the potential for applications in direct methanol fuel cells.

Atmospheric deposition of methanol over the Atlantic Ocean

Science.gov (United States)

Yang, Mingxi; Nightingale, Philip D.; Beale, Rachael; Liss, Peter S.; Blomquist, Byron; Fairall, Christopher

2013-01-01

In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air–sea methanol transfer along a ∼10,000-km north–south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air–sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface—an important term for improving air–sea gas exchange models. PMID:24277830

Optimization for microwave-assisted direct liquefaction of bamboo residue in glycerol/methanol mixtures

Science.gov (United States)

Jiulong Xie; Jinqiu Qi; Chungyun Hse; Todd F. Shupe

2015-01-01

Bamboo residues were liquefied in a mixture of glycerol and methanol in the presence of sulfuric acid using microwave energy. We investigated the effects of liquefaction conditions, including glycerol/methanol ratio, liquefaction temperature, and reaction time on the conversion yield. The optimal liquefaction conditions were under the temperature of 120

Mechanistic Studies on Chabazite-Type Methanol-to-Olefin Catalysts: Insights from Time-Resolved UV/Vis Microspectroscopy Combined with Theoretical Simulations

NARCIS (Netherlands)

Van Speybroeck, V.; Hemelsoet, K.L.J.; De Wispelaere, K.; Qian, Q.|info:eu-repo/dai/nl/34138609X; Van der Mynsbrugge, J.; De Sterck, B.; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Waroquier, M.

2013-01-01

The formation and nature of active sites for methanol conversion over solid acid catalyst materials are studied by using a unique combined spectroscopic and theoretical approach. A working catalyst for the methanol-to-olefin conversion has a hybrid organic–inorganic nature in which a cocatalytic

Methanol utilizing Desulfotomaculum species utilizes hydrogen in a methanol-fed sulfate-reducing bioreactor.

Science.gov (United States)

Balk, Melike; Weijma, Jan; Goorissen, Heleen P; Ronteltap, Mariska; Hansen, Theo A; Stams, Alfons J M

2007-01-01

A sulfate-reducing bacterium, strain WW1, was isolated from a thermophilic bioreactor operated at 65 degrees C with methanol as sole energy source in the presence of sulfate. Growth of strain WW1 on methanol or acetate was inhibited at a sulfide concentration of 200 mg l(-1), while on H2/CO2, no apparent inhibition occurred up to a concentration of 500 mg l(-1). When strain WW1 was co-cultured under the same conditions with the methanol-utilizing, non-sulfate-reducing bacteria, Thermotoga lettingae and Moorella mulderi, both originating from the same bioreactor, growth and sulfide formation were observed up to 430 mg l(-1). These results indicated that in the co-cultures, a major part of the electron flow was directed from methanol via H2/CO2 to the reduction of sulfate to sulfide. Besides methanol, acetate, and hydrogen, strain WW1 was also able to use formate, malate, fumarate, propionate, succinate, butyrate, ethanol, propanol, butanol, isobutanol, with concomitant reduction of sulfate to sulfide. In the absence of sulfate, strain WW1 grew only on pyruvate and lactate. On the basis of 16S rRNA analysis, strain WW1 was most closely related to Desulfotomaculum thermocisternum and Desulfotomaculum australicum. However, physiological properties of strain WW1 differed in some aspects from those of the two related bacteria.

Study of SI engine fueled with methanol vapor and dissociation gas based on exhaust heat dissociating methanol

International Nuclear Information System (INIS)

Fu, Jianqin; Deng, Banglin; Liu, Jingping; Wang, Linjun; Xu, Zhengxin; Yang, Jing; Shu, Gequn

2014-01-01

Highlights: • The full load power decreases successively from gasoline engine, methanol vapor engine to dissociated methanol engine. • Both power and thermal efficiency of dissociated methanol engine can be improved by boosting pressure. • The conversion efficiency of recovered exhaust gas energy is largely influenced by the BMEP. • At the same BMEP, dissociated methanol engine has higher thermal efficiency than methanol vapor engine and gasoline engine. - Abstract: To improve the fuel efficiency of internal combustion (IC) engine and also achieve the goal of direct usage of methanol fuel on IC engine, an approach of exhaust heat dissociating methanol was investigated, which is a kind of method for IC engine exhaust heat recovery (EHR). A bottom cycle system is coupled with the IC engine exhaust system, which uses the exhaust heat to evaporate and dissociate methanol in its catalytic cracker. The methanol dissociation gas (including methanol vapor) is used as the fuel for IC engine. This approach was applied to both naturally aspirated (NA) engine and turbocharged engine, and the engine performance parameters were predicted by the software GT-power under various kinds of operating conditions. The improvement to IC engine performance and the conversion efficiency of recovered exhaust gas energy can be evaluated by comparing the performances of IC engine fueled with various kinds of fuels (or their compositions). Results show that, from gasoline engine, methanol vapor engine to dissociated methanol engine, the full load power decreases successively in the entire speed area due to the declining of volumetric efficiency, while it is contrary in the thermal efficiency at the same brake mean effective pressure (BMEP) level because of the improving of fuel heating value. With the increase of BMEP, the conversion efficiency of recovered exhaust gas energy is promoted. All those results indicate that the approach of exhaust heat dissociating methanol has large

Studies of the role of water in the electrocatalysis of methanol oxidation

Science.gov (United States)

Lin, Andrew S.; Kowalak, Albert D.; O'Grady, William E.

The oxidation of methanol has been carried out on electrodes prepared by evaporating Pt directly onto a Nafion membrane and then introducing the methanol either in the gas-fed mode or directly from the electrolyte in the electrolyte-fed mode. It was found that the oxidation carried out using a gas-fed electrode was shifted 100-150 mV more cathodic than the electrolyte-fed electrode. A similar set of experiments was carried out using hydrophobic gas-diffusion electrodes and similar results were obtained. These results suggest that the mechanism of the methanol oxidation reaction depends on the nature of the surroundings and the orientation of the methanol with respect to the electrode surface. In the electrolyte-fed configuration the methanol will be in a hydrogen-bonded water cluster allowing the carbon end of the molecule to more readily approach the catalyst surface. While in the gas-fed configuration the methanol will interact with the water or oxidic surface through the hydroxyl end of the molecule. Clearly, these two possible mechanisms will lead to different products and one may enhance the rate of the direct oxidation of methanol as observed in this work.

Study of catalysis for solid oxide fuel cells and direct methanol fuel cells

Science.gov (United States)

Jiang, Xirong

Fuel cells offer the enticing promise of cleaner electricity with lower environmental impact than traditional energy conversion technologies. Driven by the interest in power sources for portable electronics, and distributed generation and automotive propulsion markets, active development efforts in the technologies of both solid oxide fuel cell (SOFC) and direct methanol fuel cell (DMFC) devices have achieved significant progress. However, current catalysts for fuel cells are either of low catalytic activity or extremely expensive, presenting a key barrier toward the widespread commercialization of fuel cell devices. In this thesis work, atomic layer deposition (ALD), a novel thin film deposition technique, was employed to apply catalytic Pt to SOFC, and investigate both Pt skin catalysts and Pt-Ru catalysts for methanol oxidation, a very important reaction for DMFC, to increase the activity and utilization levels of the catalysts while simultaneously reducing the catalyst loading. For SOFCs, we explored the use of ALD for the fabrication of electrode components, including an ultra-thin Pt film for use as the electrocatalyst, and a Pt mesh structure for a current collector for SOFCs, aiming for precise control over the catalyst loading and catalyst geometry, and enhancement in the current collect efficiency. We choose Pt since it has high chemical stability and excellent catalytic activity for the O2 reduction reaction and the H2 oxidation reaction even at low operating temperatures. Working SOFC fuel cells were fabricated with ALD-deposited Pt thin films as an electrode/catalyst layer. The measured fuel cell performance reveals that comparable peak power densities were achieved for ALD-deposited Pt anodes with only one-fifth of the Pt loading relative to a DC-sputtered counterpart. In addition to the continuous electrocatalyst layer, a micro-patterned Pt structure was developed via the technique of area selective ALD. By coating yttria-stabilized zirconia, a

Highly effective and CO-tolerant PtRu electrocatalysts supported on poly(ethyleneimine) functionalized carbon nanotubes for direct methanol fuel cells

International Nuclear Information System (INIS)

Cheng, Yi; Jiang, San Ping

2013-01-01

A highly efficient and CO tolerant PtRu electrocatalysts supported on amino-rich, cationic poly(ethyleneimine) polyelectrolyte functionalized multi-walled carbon nanotubes (PtRu/PEI-MWCNTs) has been developed. The catalysts were characterized by thermogravimetric analysis, Raman spectroscopy, cyclic voltammograms, CO stripping, chronoamperometry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The PtRu particles with average size ∼2.5 nm are well dispersed on PEI-MWCNTs. The peak current for the methanol oxidation reaction on 40% PtRu/PEI-MWCNTs is 636mAmg Pt −1 , 5.7 times higher than 112mA mg Pt −1 measured on the 40% PtRu supported on acid treated MWCNTs (PtRu/AO-MWCNTs) under identical conditions. PtRu/PEI-MWCNTs catalysts exhibit a superior electrocatalytic activity and stability for the methanol oxidation reaction due to its high tolerance toward CO poisoning as compared with PtRu/AO-MWCNTs for direct methanol fuel cells

Formation of carbonyl compounds in radiolysis of ethylene glycol in methanol

International Nuclear Information System (INIS)

Bezborodova, S.G.; Vetrov, V.S.; Kalyazin, E.P.; Korolev, V.M.; Salamatov, I.I.

1977-01-01

Radiolysis of diluted solutions of ethylene glycol has been investigated. It is shown that acetaldehyde, glycol aldehyde and formaldehyde are the main products of radiolysis of methanol solutions of ethylene glycol. Acetaldehyde and glycol aldehyde yields increase in radiolysis of methanol solutions of ethylene glycol with an increase of the original concentration of ethylene glycol and a temperature rise of radiolysis. Formaldehyde yields increase with the ethylene glycol concentration but decrease with a temperature rise (the formation of formaldehyde from methanol is taken into account). A mechanism of radiation-chemical transformations of ethylene glycol in methanol is explained. It is concluded that the main directions of ethylene glycol decomposition, detected in water solutions of ethylene glycol, are also realized in methanol solutions. However, a role of different directions of decomposition depends on the medium

Process for obtaining methanol. Verfahren zur Gewinnung von Methanol

Energy Technology Data Exchange (ETDEWEB)

Link, H; Watson, A

1983-12-08

Synthetic gas is generated and converted to methanol in a reactor. After the separation of the crude methanol, there is a multi-stage methanol distillation. Condensate occurring during distillation is at least partly fed back before the methanol synthesis.

An Investigation of Palladium Oxygen Reduction Catalysts for the Direct Methanol Fuel Cell

Directory of Open Access Journals (Sweden)

G. F. Álvarez

2011-01-01

Full Text Available A comparative study of Pd and Pt was carried out in DMFC using different methanol concentrations and under different operating conditions. Cell performance was compared at methanol concentrations of 1, 3, 5, and 7 M and at temperatures of 20, 40, and 60°C. Homemade Pd nanoparticles were prepared on Vulcan XC-72R using ethylene glycol as the reducing agent at pH 11. The resulting catalyst, Pd/C, with metal nanoparticles of approximately 6 nm diameter, was tested as a cathode catalyst in DMFC. At methanol concentrations of 5 M and higher, the Pd cathode-based cell performed better than that with Pt at 60°C with air.

Mass transport of direct methanol fuel cell species in sulfonated poly(ether ether ketone) membranes

International Nuclear Information System (INIS)

Silva, V.S.; Ruffmann, B.; Vetter, S.; Boaventura, M.; Mendes, A.M.; Madeira, L.M.; Nunes, S.P.

2006-01-01

Homogeneous membranes based on sulfonated poly(ether ether ketone) (sPEEK) with different sulfonation degrees (SD) were prepared and characterized. In order to perform a critical analysis of the SD effect on the polymer barrier and mass transport properties towards direct methanol fuel cell species, proton conductivity, water/methanol pervaporation and nitrogen/oxygen/carbon dioxide pressure rise method experiments are proposed. This procedure allows the evaluation of the individual permeability coefficients in hydrated sPEEK membranes with different sulfonation degrees. Nafion[reg] 112 was used as reference material. DMFC tests were also performed at 50 deg. C. It was observed that the proton conductivity and the permeability towards water, methanol, oxygen and carbon dioxide increase with the sPEEK sulfonation degree. In contrast, the SD seems to not affect the nitrogen permeability coefficient. In terms of selectivity, it was observed that the carbon dioxide/oxygen selectivity increases with the sPEEK SD. In contrast, the nitrogen/oxygen selectivity decreases. In terms of barrier properties for preventing the DMFC reactants loss, the polymer electrolyte membrane based on the sulfonated poly(ether ether ketone) with SD lower or equal to 71%, although having slightly lower proton conductivity, presented much better characteristics for fuel cell applications compared with the well known Nafion[reg] 112. In terms of the DMFC tests of the studied membranes at low temperature, the sPEEK membrane with SD = 71% showed to have similar performance, or even better, as that of Nafion[reg] 112. However, the highest DMFC overall efficiency was achieved using sPEEK membrane with SD = 52%

Comparison between two methods of methanol production from carbon dioxide

International Nuclear Information System (INIS)

Anicic, B.; Trop, P.; Goricanec, D.

2014-01-01

Over recent years there has been a significant increase in the amount of technology contributing to lower emissions of carbon dioxide. The aim of this paper is to provide a comparison between two technologies for methanol production, both of which use carbon dioxide and hydrogen as initial raw materials. The first methanol production technology includes direct synthesis of methanol from CO 2 , and the second has two steps. During the first step CO 2 is converted into CO via RWGS (reverse water gas shift) reaction, and methanol is produced during the second step. A comparison between these two methods was achieved in terms of economical and energy-efficiency bases. The price of electricity had the greatest impact from the economical point of view as hydrogen is produced via the electrolysis of water. Furthermore, both the cost of CO 2 capture and the amounts of carbon taxes were taken into consideration. Energy-efficiency comparison is based on cold gas efficiency, while economic feasibility is compared using net present value. Even though the mentioned processes are similar, it was shown that direct methanol synthesis has higher energy and economic efficiency. - Highlights: • We compared two methods for methanol production. • Process schemes for both, direct synthesis and two-step synthesis, are described. • Direct synthesis has higher economical and energy efficiency

Direct methanol fuel cells: Pt-Ni/C binary electrocatalysts; Celulas a combutivel de metanol direto: eletrocatalisadores binarios de Pt-Ni/C

Energy Technology Data Exchange (ETDEWEB)

Salgado, Jose Ricardo Cezar; Antolini, Ermete; Santos, Ana Maria dos; Gonzalez, Ernesto Rafael [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Quimica], e-mail: salgado@iqsc.usp.br

2004-07-01

Direct methanol fuel cells use platinum alloys as more efficient catalysts than platinum. In the case of binary alloys, the second metal affects several properties of platinum, like the interatomic distance, the electronic density and the capacity of forming oxygenated species at lower potentials. In this work, Pt-Ni catalysts supported on high surface area carbon (Pt-Ni/C) were prepared and characterized, and tested as catalysts in the anode and the cathode in direct methanol fuel cells. In both cases the performance of the material was better than that of Pt/C, and comparing the two situations it was better when the material was used in the cathode. The improved performance in the cathode was attributed to the nickel that forms a true alloy with platinum, while the better performance in the anode was attributed to the presence of nickel oxides. (author)

Fast Measurement of Methanol Concentration in Ionic Liquids by Potential Step Method

Directory of Open Access Journals (Sweden)

Michael L. Hainstock

2015-01-01

Full Text Available The development of direct methanol fuel cells required the attention to the electrolyte. A good electrolyte should not only be ionic conductive but also be crossover resistant. Ionic liquids could be a promising electrolyte for fuel cells. Monitoring methanol was critical in several locations in a direct methanol fuel cell. Conductivity could be used to monitor the methanol content in ionic liquids. The conductivity of 1-butyl-3-methylimidazolium tetrafluoroborate had a linear relationship with the methanol concentration. However, the conductivity was significantly affected by the moisture or water content in the ionic liquid. On the contrary, potential step could be used in sensing methanol in ionic liquids. This method was not affected by the water content. The sampling current at a properly selected sampling time was proportional to the concentration of methanol in 1-butyl-3-methylimidazolium tetrafluoroborate. The linearity still stood even when there was 2.4 M water present in the ionic liquid.

Evaluation of sulfonated polysulfone/zirconium hydrogen phosphate composite membranes for direct methanol fuel cells

International Nuclear Information System (INIS)

Ozden, Adnan; Ercelik, Mustafa; Devrim, Yilser; Colpan, C. Ozgur; Hamdullahpur, Feridun

2017-01-01

Highlights: •Very thin SPSf/ZrP composite membranes were prepared by solution casting method. •The viability of SPSf/ZrP membranes for DMFCs was investigated for the first time. •Superior proton conductivity over Nafion ® 115 was achieved between 45–80 °C. •Desired membrane characteristics, along with low manufacturing cost were achieved. •Single cell DMFC performance was improved up to 13%. -- Abstract: Direct methanol fuel cell (DMFC) technology has advanced perceivably, but technical challenges remain that must be overcome for further performance improvements. Thus, in this study, sulfonated polysulfone/zirconium hydrogen phosphate (SPSf/ZrP) composite membranes with various sulfonation degrees (20%, 35%, and 42%) and a constant concentration of ZrP (2.5%) were prepared to mitigate the technical challenges associated with the use of conventional Nafion ® membranes in DMFCs. The composite membranes were investigated through Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), Thermogravimetric Analysis (TGA), oxidative stability and water uptake measurements, and single cell testing. Comparison was also made with Nafion ® 115. Single cell tests were performed under various methanol concentrations and cell temperatures. Stability characteristics of the DMFCs under charging and discharging conditions were investigated via 1200 min short-term stability tests. The response characteristics of the DMFCs under dynamic conditions were determined at the start-up and shut-down stages. Composite membranes with sulfonation degrees of 35% and 42% were found to be highly promising due to their advanced characteristics with respect to proton conductivity, water uptake, thermal resistance, oxidative stability, and methanol suppression. For the whole range of parameters studied, the maximum power density obtained for SPSf/ZrP-42 (119 mW cm −2 ) was found to be 13% higher than that obtained for Nafion ® 115 (105 mW cm −2 ).

Upgrade of hybrid fibre coax networks towards bi-directional access

NARCIS (Netherlands)

Khoe, G.D.; Wolters, R.P.C.; Boom, van den H.P.A.; Prati, G.

1997-01-01

In this paper we describe an upgrade scenario for Hybrid Fibre Coax (HFC) CATV Networks towards hi-directional access. The communication system described has been newly designed, and is based on the use of Direct Sequence- Code Division Multiple-Access (DS-CDMA). Due to its spread-spectrum

Cathode-supported hybrid direct carbon fuel cells

DEFF Research Database (Denmark)

Gil, Vanesa; Gurauskis, Jonas; Deleebeeck, Lisa

2017-01-01

The direct conversion of coal to heat and electricity by a hybrid direct carbon fuel cell (HDCFC) is a highly efficient and cleaner technology than the conventional combustion power plants. HDCFC is defined as a combination of solid oxide fuel cell and molten carbonate fuel cell. This work...... investigates cathode-supported cells as an alternative configuration for HDCFC, with better catalytic activity and performance. This study aims to define the best processing route to manufacture highly efficient cathode-supported cells based on La0.75Sr0.25MnO3/yttria-stabilized zirconia infiltrated backbones...

Enhanced methanol electro-oxidation reaction on Pt-CoOx/MWCNTs hybrid electro-catalyst

International Nuclear Information System (INIS)

Nouralishahi, Amideddin; Rashidi, Ali Morad; Mortazavi, Yadollah; Khodadadi, Abbas Ali; Choolaei, Mohammadmehdi

2015-01-01

Highlights: • Promoting effects of Cobalt oxide on methanol electro-oxidation over Pt/MWCNTs are investigated. • Higher activity, about 2.9 times, and enhanced stability are observed on Pt-CoO x /MWCNTs. • Electrochemical active surface area of Pt nanoparticles is significantly improved upon CoO x addition. • Bi-functional mechanism is facilitated in presence of CoO x . - Abstract: The electro-catalytic behavior of Pt-CoO x /MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH 4  as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoO x , Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of CO ads on Pt active sites by the participation of CoO x . Compared to Pt/MWCNTs, Pt-CoO x /MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoO x /MWCNTs, at small overpotentials. However, at higher overpotentials, the oxidation of adsorbed oxygen-containing groups

Formaldehyde, methanol and hydrocarbon emissions from methanol-fueled cars

International Nuclear Information System (INIS)

Williams, R.L.; Lipari, F.; Potter, R.A.

1990-01-01

Exhaust and evaporative emissions tests were conducted on several methanol- and gasoline-fueled vehicles. Separate samples for chromatographic analysis of formaldehyde, methanol, and individual hydrocarbons were collected in each of the three phases of the driving cycle and in each of the two portions of the evaporative emissions test. One vehicle, equipped with an experimental variable-fuel engine, was tested using methanol/gasoline fuel mixtures of 100, 85, 50, 15, and 0 percent methanol. Combustion-generated hydrocarbons were lowest using methanol fuel, and increased several-fold as the gasoline fraction was increased. Gasoline components in the exhaust increased from zero as the gasoline fraction of the fuel was increased. On the other hand, formaldehyde emissions were several times higher using methanol fuel than they were using gasoline. A dedicated methanol car and the variable-fuel car gave similar emissions patterns when they both were tested using methanol fuel. The organic-carbon composition of the exhaust was 85-90 percent methanol, 5-7 percent formaldehyde, and 3-9 percent hydrocarbons. Several cars that were tested using gasoline emitted similar distributions of hydrocarbons, even through the vehicles represented a broad range of current and developmental engine families and emissions control systems

In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation

Directory of Open Access Journals (Sweden)

Xi Geng

2015-01-01

Full Text Available PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI- functionalized multiwalled carbon nanotubes (MWCNTs via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray powder diffraction (XRD, and energy dispersive X-ray spectroscopy (EDX, respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC.

Direct hydrogen fuel cell systems for hybrid vehicles

Science.gov (United States)

Ahluwalia, Rajesh K.; Wang, X.

Hybridizing a fuel cell system with an energy storage system offers an opportunity to improve the fuel economy of the vehicle through regenerative braking and possibly to increase the specific power and decrease the cost of the combined energy conversion and storage systems. Even in a hybrid configuration it is advantageous to operate the fuel cell system in a load-following mode and use the power from the energy storage system when the fuel cell alone cannot meet the power demand. This paper discusses an approach for designing load-following fuel cell systems for hybrid vehicles and illustrates it by applying it to pressurized, direct hydrogen, polymer-electrolyte fuel cell (PEFC) systems for a mid-size family sedan. The vehicle level requirements relative to traction power, response time, start-up time and energy conversion efficiency are used to select the important parameters for the PEFC stack, air management system, heat rejection system and the water management system.

Highly Durable Direct Methanol Fuel Cell with Double-Layered Catalyst Cathode

Directory of Open Access Journals (Sweden)

Jing Liu

2015-01-01

Full Text Available Polymer electrolyte membrane (PEM is one of the key components in direct methanol fuel cells. However, the PEM usually gets attacked by reactive oxygen species during the operation period, resulting in the loss of membrane integrity and formation of defects. Herein, a double-layered catalyst cathode electrode consisting of Pt/CeO2-C as inner catalyst and Pt/C as outer catalyst is fabricated to extend the lifetime and minimize the performance loss of DMFC. Although the maximum power density of membrane electrode assembly (MEA with catalyst cathode is slightly lower than that of the traditional one, its durability is significantly improved. No obvious degradation is evident in the MEA with double-layered catalyst cathode within durability testing. These results indicated that Pt/CeO2-C as inner cathode catalyst layer greatly improved the stability of MEA. The significant reason for the improved stability of MEA is the ability of CeO2 to act as free-radical scavengers.

Design, fabrication and performance of a mixed-reactant membraneless micro direct methanol fuel cell stack

Science.gov (United States)

Abrego-Martínez, J. C.; Moreno-Zuria, A.; Cuevas-Muñiz, F. M.; Arriaga, L. G.; Sun, Shuhui; Mohamedi, Mohamed

2017-12-01

In the present work, we report the design, fabrication and evaluation of a membraneless mixed-reactant and air-breathing microfluidic direct methanol fuel cell (ML-μDMFC) stack operated in passive mode. The operation under mixed-reactant conditions was achieved by using a highly methanol-tolerant Ag/Pt/CP cathode with ultra-low Pt loading in alkaline medium. Prior to the fabrication of the stack, a flow simulation was made in order to study the behavior of the reactants stream in the microchannel through the 2 cells. Subsequently, the device was tested in passive mode using a mixture of 5 M MeOH +0.5 M KOH. The results showed that by connecting the 2 cells in series, it is possible to effectively double the voltage of a single ML-μDMFC, as well as increasing the absolute power by 75% with practically no cost increase. The stack was capable of operate continuously for more than 2 h with a single charge of 40 μL, producing an OCV of 0.89 V and a maximum power density of 3.33 mW mgPt-1. Additionally, the device exhibited good stability throughout a 10 h test.

Highly water-dispersible, mixed ionic-electronic conducting, polymer acid-doped polyanilines as ionomers for direct methanol fuel cells.

Science.gov (United States)

Murthy, Arun; Manthiram, Arumugam

2011-06-28

Highly water-dispersible polymer acid-doped polyanilines have been synthesized and evaluated as an alternative for expensive Nafion ionomers in the anode of direct methanol fuel cells (DMFC). These polymers as ionomers lead to higher performance in single cell DMFC compared to Nafion ionomers due to mixed ionic-electronic conduction, water dispersibility, and co-catalytic activity. This journal is © The Royal Society of Chemistry 2011

Micro direct methanol fuel cell with perforated silicon-plate integrated ionomer membrane

DEFF Research Database (Denmark)

Larsen, Jackie Vincent; Dalslet, Bjarke Thomas; Johansson, Anne-Charlotte Elisabeth Birgitta

2014-01-01

This article describes the fabrication and characterization of a silicon based micro direct methanol fuel cell using a Nafion ionomer membrane integrated into a perforated silicon plate. The focus of this work is to provide a platform for micro- and nanostructuring of a combined current collector...... at a perforation ratio of 40.3%. The presented fuel cells also show a high volumetric peak power density of 2 mW cm−3 in light of the small system volume of 480 μL, while being fully self contained and passively feed....... and catalytic electrode. AC impedance spectroscopy is utilized alongside IV characterization to determine the influence of the plate perforation geometries on the cell performance. It is found that higher ratios of perforation increases peak power density, with the highest achieved being 2.5 mW cm−2...

Enhanced activity and durability of platinum anode catalyst by the modification of cobalt phosphide for direct methanol fuel cells

International Nuclear Information System (INIS)

Li, Xiang; Wang, Hongjuan; Yu, Hao; Liu, Ziwu; Wang, Haihui; Peng, Feng

2015-01-01

Graphical abstract: A novel Pt/CoP/CNTs electrocatalyst with has been designed and prepared, which exhibits high activity and stability for methanol oxidation reaction. - Highlights: • Pt-cobalt phosphide catalyst supported on carbon nanotubes (Pt/CoP/CNTs) is designed. • Pt/CoP/CNTs exhibit high activity and stability for methanol oxidation reaction(MOR). • The effect of CoP content on electrocatalytic performances for MOR is studied. • CoP decreases the Pt particle size and increases the electrochemical surface areas. • The interaction between Pt and CoP is evidenced by X-ray photoelectron spectroscopy. - Abstract: In this study, carbon nanotubes (CNTs) supported Pt-cobalt phosphide (CoP) electrocatalyst (Pt/CoP/CNTs) is designed and prepared for methanol oxidation (MOR) for the first time. The modification of CoP decreases the Pt particle size significantly and increases the electrochemical surface areas due to the interaction between Pt and CoP, which is evidenced by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Among all these catalysts, Pt/4%CoP/CNTs catalyst exhibits the best MOR activity of 1600 mA mg −1 Pt , which is six times that of Pt/CNTs. Moreover, this catalyst also exhibits the higher onset current density and steady current density than the other Pt-based catalysts. The work provides a promising method to develop the highly active and stable Pt-based catalyst for direct methanol fuel cells.

Co-deposition of Pt and ceria anode catalyst in supercritical carbon dioxide for direct methanol fuel cell applications

International Nuclear Information System (INIS)

You, Eunyoung; Guzmán-Blas, Rolando; Nicolau, Eduardo; Aulice Scibioh, M.; Karanikas, Christos F.; Watkins, James J.; Cabrera, Carlos R.

2012-01-01

Pt and mixed Pt-ceria catalysts were deposited onto gas diffusion layers using supercritical fluid deposition (SFD) to fabricate thin layer electrodes for direct methanol fuel cells. Dimethyl (1,5-cyclooctadiene) platinum (II) (CODPtMe 2 ) and tetrakis (2,2,6,6-tetramethyl 3,5-heptanedionato) cerium (IV) (Ce(tmhd) 4 ) were used as precursors. Hydrogen-assisted Pt deposition was performed in compressed carbon dioxide at 60 °C and 17.2 MPa to yield high purity Pt on carbon-black based gas diffusion layers. During the preparation of the mixed Pt-ceria catalyst, hydrogen reduction of CODPtMe 2 to yield Pt catalyzed the deposition of ceria from Ce(tmhd) 4 enabling co-deposition at 150 °C. The catalyst layers were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope-energy dispersive spectral (SEM-EDS) analyses. Their electrochemical performance toward methanol oxidation was examined in half cell mode using a three electrode assembly as well as in fuel cell mode. The thin layer electrodes formed via SFD exhibited higher performance in fuel cell operations compared to those prepared by the conventional brush-paint method. Furthermore, the Pt-ceria catalyst with an optimized composition exhibited greater methanol oxidation activity than pure platinum.

Ultrashort hybrid metal-insulator plasmonic directional coupler.

Science.gov (United States)

Noghani, Mahmoud Talafi; Samiei, Mohammad Hashem Vadjed

2013-11-01

An ultrashort plasmonic directional coupler based on the hybrid metal-insulator slab waveguide is proposed and analyzed at the telecommunication wavelength of 1550 nm. It is first analyzed using the supermode theory based on mode analysis via the transfer matrix method in the interaction region. Then the 2D model of the coupler, including transition arms, is analyzed using a commercial finite-element method simulator. The hybrid slab waveguide is composed of a metallic layer of silver and two dielectric layers of silica (SiO2) and silicon (Si). The coupler is optimized to have a minimum coupling length and to transfer maximum power considering the layer thicknesses as optimization variables. The resulting coupling length in the submicrometer region along with a noticeable power transfer efficiency are advantages of the proposed coupler compared to previously reported plasmonic couplers.

One-Pot and Facile Fabrication of Hierarchical Branched Pt-Cu Nanoparticles as Excellent Electrocatalysts for Direct Methanol Fuel Cells.

Science.gov (United States)

Cao, Yanqin; Yang, Yong; Shan, Yufeng; Huang, Zhengren

2016-03-09

Hierarchical branched nanoparticles are one promising nanostructure with three-dimensional open porous structure composed of integrated branches for superior catalysis. We have successfully synthesized Pt-Cu hierarchical branched nanoparticles (HBNDs) with small size of about 30 nm and composed of integrated ultrathin branches by using a modified polyol process with introduction of poly(vinylpyrrolidone) and HCl. This strategy is expected to be a general strategy to prepare various metallic nanostructures for catalysis. Because of the special open porous structure, the as-prepared Pt-Cu HBNDs exhibit greatly enhanced specific activity toward the methanol oxidation reaction as much as 2.5 and 1.7 times compared with that of the commercial Pt-Ru and Pt-Ru/C catalysts, respectively. Therefore, they are potentially applicable as electrocatalysts for direct methanol fuel cells.

Surface tailored single walled carbon nanotubes as catalyst support for direct methanol fuel cell

Science.gov (United States)

Kireeti, Kota V. M. K.; Jha, Neetu

2017-10-01

A strategy for tuning the surface property of Single Walled Carbon Nanotubes (SWNTs) for enhanced methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) along with methanol tolerance is presented. The surface functionality is tailored using controlled acid and base treatment. Acid treatment leads to the attachment of carboxylic carbon (CC) fragments to SWNT making it hydrophilic (P3-SWNT). Base treatment of P3-SWNT with 0.05 M NaOH reduces the CCs and makes it hydrophobic (P33-SWNT). Pt catalyst supported on the P3-SWNT possesses enhanced MOR whereas that supported on P33-SWNT not only enhances ORR kinetics but also possess good tolerance towards methanol oxidation as verified by the electrochemical technique.

Carbon nanotubes based methanol sensor for fuel cells application.

Science.gov (United States)

Kim, D W; Lee, J S; Lee, G S; Overzet, L; Kozlov, M; Aliev, A E; Park, Y W; Yang, D J

2006-11-01

An electrochemical sensor is built using vertically grown multi-walled carbon nanotubes (MWNTs) micro-array to detect methanol concentration in water. This study is done for the potential use of the array as methanol sensor for portable units of direct methanol fuel cells (DMFCs). Platinum (Pt) nanoparticles electro-deposited CNTs (Pt/CNTs) electrode shows high sensitivity in the measurement of methanol concentration in water with cyclic voltammetry (CV) measurement at room temperature. Further investigation has also been undertaken to measure the concentration by changing the amount of the mixture of methanol and formic acid in water. We compared the performance of our micro array sensor built with Pt/CNTs electrodes versus that of Pt wire electrode using CV measurement. We found that our Pt/CNTs array sensor shows high sensitivity and detects methanol concentrations in the range of 0.04 M to 0.10 M. In addition, we found that co-use of formic acid as electrolyte enables us to measure up to 1.0 M methanol concentration.

Three-dimensional two-phase mass transport model for direct methanol fuel cells

International Nuclear Information System (INIS)

Yang, W.W.; Zhao, T.S.; Xu, C.

2007-01-01

A three-dimensional (3D) steady-state model for liquid feed direct methanol fuel cells (DMFC) is presented in this paper. This 3D mass transport model is formed by integrating five sub-models, including a modified drift-flux model for the anode flow field, a two-phase mass transport model for the porous anode, a single-phase model for the polymer electrolyte membrane, a two-phase mass transport model for the porous cathode, and a homogeneous mist-flow model for the cathode flow field. The two-phase mass transport models take account the effect of non-equilibrium evaporation/ condensation at the gas-liquid interface. A 3D computer code is then developed based on the integrated model. After being validated against the experimental data reported in the literature, the code was used to investigate numerically transport behaviors at the DMFC anode and their effects on cell performance

Manufacturing technologies for direct methanol fuel cells (DMFCs)

Energy Technology Data Exchange (ETDEWEB)

Gluesen, Andreas; Mueller, Martin; Kimiaie, Nicola; Konradi, Irene; Mergel, Juergen; Stolten, Detlef [Forschungszentrum Juelich (Germany). Inst. of Energy Research - IEF-3: Fuel Cells

2010-07-01

Fuel cell research is focussing on increasing power density and lifetime and reducing costs of the whole fuel cell system. In order to reach these aims, it is necessary to develop appropriately designed components outgoing from high quality materials, a suitable manufacturing process and a well balanced system. To make use of the advantages that can be obtained by developing production technology, we are mainly improving the coating and assembling techniques for polymer electrolyte fuel cells, especially Direct Methanol Fuel Cells (DMFCs). Coating is used for making fuel cell electrodes as well as highly conductive contacts. Assembling is used to join larger components like membrane electrode assemblies (MEAs) and bipolar units consisting of flow fields and the separator plate, as well as entire stacks. On the one hand a reproducible manufacturing process is required to study fine differences in fuel cell performance affected by new materials or new designs. On the other hand a change in each parameter of the manufacturing process itself can change product properties and therefore affect fuel cell performance. As a result, gas diffusion electrodes (GDEs) are now produced automatically in square-meter batches, the hot-pressing of MEAs is a fully automated process and by pre-assembling the number of parts that have to be assembled in a stack was reduced by a factor of 10. These achievements make DMFC manufacturing more reproducible and less error-prone. All these and further developments of manufacturing technology are necessary to make DMFCs ready for the market. (orig.)

A DFT study of methanol adsorption in 8T rings of chabazite

NARCIS (Netherlands)

Mihaleva, V.V.; Santen, van R.A.; Jansen, A.P.J.

2001-01-01

Hybrid B3LYP and gradient-corrected PW91 functionals were used for studying methanol adsorption on a zeolite cluster consisting of an 8T ring of chabazite. The comparison of the results obtained with PW91 with periodic calculations has shown that the adopted ring is an adequate approximation for the

High temperature transport properties of polyphosphazene membranes for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Xiangyang Zhou; Chalkova, E. [Pennsylvania State University (United States). The Energy Institute; Weston, J.; Lvov, S.N. [Pennsylvania State University (United States). The Energy Institute; Pennsylvania State University (United States). Department of Energy and Geo-Environment Engineering; Hofmann, M.A.; Ambler, C.M.; Allcock, H.R. [Pennsylvania State University (United States). Department of Chemistry

2003-06-30

Experimental methods for studying the conductivity and methanol permeability of proton conductive polymers over a wide range of temperatures have been developed. The proton conductivity and methanol permeability of several polymer electrolyte membranes including sulfonated and phosphonated poly[(aryloxy)phosphazenes] was determined at temperatures up to 120 {sup o}C. Nafion 117 membranes were tested using the same methods in order to determine the reliability of the methods. Although the conductivities of the polyphosphazene membranes were either similar to or lower than that of the Nafion 117 membranes, they continue to hold promise for fuel cell applications. We observed similar activation energies of proton conduction for Nafion 117, and for sulfonated and phosphonated polyphosphazene membranes. However, the methanol permeability of a sulfonated membrane was about 8 times lower than that of the Nafion 117 membrane at room temperature although the values were comparable at 120 {sup o}C. The permeability of a phosphonated phosphazene derivative was about 40 times lower than that of the Nafion 117 membrane at room temperature and about 9 times lower at 120 {sup o}C. This is a significant improvement over the behavior of Nafion 117. (author)

High temperature transport properties of polyphosphazene membranes for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Zhou Xiangyang; Weston, Jamie; Chalkova, Elena; Hofmann, Michael A.; Ambler, Catherine M.; Allcock, Harry R.; Lvov, Serguei N

2003-06-30

Experimental methods for studying the conductivity and methanol permeability of proton conductive polymers over a wide range of temperatures have been developed. The proton conductivity and methanol permeability of several polymer electrolyte membranes including sulfonated and phosphonated poly[(aryloxy)phosphazenes] was determined at temperatures up to 120 deg. C. Nafion 117 membranes were tested using the same methods in order to determine the reliability of the methods. Although the conductivities of the polyphosphazene membranes were either similar to or lower than that of the Nafion 117 membranes, they continue to hold promise for fuel cell applications. We observed similar activation energies of proton conduction for Nafion 117, and for sulfonated and phosphonated polyphosphazene membranes. However, the methanol permeability of a sulfonated membrane was about 8 times lower than that of the Nafion 117 membrane at room temperature although the values were comparable at 120 deg. C. The permeability of a phosphonated phosphazene derivative was about 40 times lower than that of the Nafion 117 membrane at room temperature and about 9 times lower at 120 deg. C. This is a significant improvement over the behavior of Nafion 117.

High temperature transport properties of polyphosphazene membranes for direct methanol fuel cells

International Nuclear Information System (INIS)

Zhou Xiangyang; Weston, Jamie; Chalkova, Elena; Hofmann, Michael A.; Ambler, Catherine M.; Allcock, Harry R.; Lvov, Serguei N.

2003-01-01

Experimental methods for studying the conductivity and methanol permeability of proton conductive polymers over a wide range of temperatures have been developed. The proton conductivity and methanol permeability of several polymer electrolyte membranes including sulfonated and phosphonated poly[(aryloxy)phosphazenes] was determined at temperatures up to 120 deg. C. Nafion 117 membranes were tested using the same methods in order to determine the reliability of the methods. Although the conductivities of the polyphosphazene membranes were either similar to or lower than that of the Nafion 117 membranes, they continue to hold promise for fuel cell applications. We observed similar activation energies of proton conduction for Nafion 117, and for sulfonated and phosphonated polyphosphazene membranes. However, the methanol permeability of a sulfonated membrane was about 8 times lower than that of the Nafion 117 membrane at room temperature although the values were comparable at 120 deg. C. The permeability of a phosphonated phosphazene derivative was about 40 times lower than that of the Nafion 117 membrane at room temperature and about 9 times lower at 120 deg. C. This is a significant improvement over the behavior of Nafion 117

Methanol commercial aviation fuel

International Nuclear Information System (INIS)

Price, R.O.

1992-01-01

Southern California's heavy reliance on petroleum-fueled transportation has resulted in significant air pollution problems within the south Coast Air Basin (Basin) which stem directly from this near total dependence on fossil fuels. To deal with this pressing issue, recently enacted state legislation has proposed mandatory introduction of clean alternative fuels into ground transportation fleets operating within this area. The commercial air transportation sector, however, also exerts a significant impact on regional air quality which may exceed emission gains achieved in the ground transportation sector. This paper addresses the potential, through the implementation of methanol as a commercial aviation fuel, to improve regional air quality within the Basin and the need to flight test and demonstrate methanol as an environmentally preferable fuel in aircraft turbine engines

Ion conductivity and mass spectrometry of methanol diffusion and electroosmotic drag on proton-conducting membranes for the Direct Methanol Fuel Cell (DMFC); Ionische Leitfaehigkeit und massenspektrometrische Bestimmung der Methanol-Diffusion und des 'Electroosmotic Drag' an protonenleitenden Membranen fuer die Direkt-Methanol-Brennstoffzelle (DMFC)

Energy Technology Data Exchange (ETDEWEB)

Oeztuerk, N.

2001-07-01

The methanol permeability of the nafion membrane is one reason why the DMFC is not marketable as yet. As a result of diffusion, permeation and electroosmotic drag, methanol is transferred to the kation side where it will reduce the fuel cell performance. Research is going on world-wide to develop new materials that will prevent methanol crossover. The report describes the development of a measuring cell that will provide the necessary information on diffusion, permeation, electroosmotic drag and conductivity. [German] Ein wesentlicher Grund, der die Einfuehrung der DMFC noch verhindert, ist die Methanoldurchlaessigkeit der Nafion-Membran. Durch Diffusion und Permeation und durch den Electroosmotic Drag gelangt Methanol auf die Kathodenseite und fuehrt dann zu einem Leistungsabfall der Brennstoffzelle. Daher werden weltweit neue Materialien entwickelt, die bei guter lonenleitfaehigkeit den Methanol-crossover unterdruecken. Zur Beurteilung und Weiterentwicklung der neuen Materialien werden Informationen zur Diffusion, Permeation, zum Electroosmotic Drag und zur Leitfaehigkeit benoetigt. Um diese Parameter schnell und einfach zu bestimmen, wurde im Rahmen der vorliegenden Arbeit eine Messzelle weiter entwickelt. Diese Messzelle erlaubt die schnelle Bestimmung aller vier wichtigen Parameter. (orig.)

Palladium-Based Catalysts as Electrodes for Direct Methanol Fuel Cells: A Last Ten Years Review

Directory of Open Access Journals (Sweden)

Juan Carlos Calderón Gómez

2016-08-01

Full Text Available Platinum-based materials are accepted as the suitable electrocatalysts for anodes and cathodes in direct methanol fuel cells (DMFCs. Nonetheless, the increased demand and scarce world reserves of Pt, as well as some technical problems associated with its use, have motivated a wide research focused to design Pd-based catalysts, considering the similar properties between this metal and Pt. In this review, we present the most recent advancements about Pd-based catalysts, considering Pd, Pd alloys with different transition metals and non-carbon supported nanoparticles, as possible electrodes in DMFCs. In the case of the anode, different reported works have highlighted the capacity of these new materials for overcoming the CO poisoning and promote the oxidation of other intermediates generated during the methanol oxidation. Regarding the cathode, the studies have showed more positive onset potentials, as fundamental parameter for determining the mechanism of the oxygen reduction reaction (ORR and thus, making them able for achieving high efficiencies, with less production of hydrogen peroxide as collateral product. This revision suggests that it is possible to replace the conventional Pt catalysts by Pd-based materials, although several efforts must be made in order to improve their performance in DMFCs.

Visualizing ignition and combustion of methanol mixtures in a diesel engine; Methanol funmu no glow chakka to nensho no kashika

Energy Technology Data Exchange (ETDEWEB)

Inomoto, Y; Harada, T; Kusaka, J; Daisho, Y; Kihara, R; Saito, T [Waseda University, Tokyo (Japan)

1997-10-01

A glow-assisted ignition system tends to suffer from poor ignitability and slow flame propagation at low load in a direct-injection diesel engine fueled with methanol. To investigate the ignition process and improve such disadvantages, methanol sprays, their ignition and flames were visualized at high pressures and temperatures using a modified two-stroke engine. The results show that parameters influencing ignition, the location of a glow-plug, swirl level, pressure and temperature are important. In addition, a full kinetics calculation was conducted to predict the delay of methanol mixture ignition by taking into account 39 chemical species and 157 elementary reactions. 3 refs., 9 figs.

Heat and mass transfer effects in a direct methanol fuel cell: A 1D model

Energy Technology Data Exchange (ETDEWEB)

Oliveira, V.B.; Falcao, D.S.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [INETI - Unidade de Electroquimica e Materiais, Paco do Lumiar, 22,1649-038 (Portugal)

2008-07-15

Models are a fundamental tool for the design process of fuel cells and fuel cell systems. In this work, a steady-state, one-dimensional model accounting for coupled heat and mass transfer, along with the electrochemical reactions occurring in the DMFC, is presented. The model output is the temperature profile through the cell and the water balance and methanol crossover between the anode and the cathode. The model predicts the correct trends for the influence of current density and methanol feed concentration on both methanol and water crossover. The model estimates the net water transfer coefficient through the membrane, {alpha}, a very important parameter to describe water management in the DMFC. Suitable operating ranges can be set up for different MEA structures maintaining the crossover of methanol and water within acceptable levels. The model is rapidly implemented and is therefore suitable for inclusion in real-time system level DMFC calculations. (author)

Experimental Validation of Methanol Crossover in a Three-dimensional, Two-Fluid Model of a Direct Methanol Fuel Cell

DEFF Research Database (Denmark)

Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

2012-01-01

A fully coupled three-dimensional, steady-state, two-fluid, multi-component and non-isothermal DMFC model has been developed in the commercial CFD package CFX 13 (ANSYS inc.). It accounts for the presence of micro porous layers, non-equilibrium phase change, and methanol and water uptake in the i...

Vertically aligned carbon nanotubes/carbon fiber paper composite to support Pt nanoparticles for direct methanol fuel cell application

Science.gov (United States)

Zhang, Jing; Yi, Xi-bin; Liu, Shuo; Fan, Hui-Li; Ju, Wei; Wang, Qi-Chun; Ma, Jie

2017-03-01

Vertically aligned carbon nanotubes (VACNTs) grown on carbon fiber paper (CFP) by plasma enhanced chemical vapor deposition is introduced as a catalyst support material for direct methanol fuel cells (DMFCs). Well dispersed Pt nanoparticles on VACNTs surface are prepared by impregnation-reduction method. The VACNTs on CFP possess well-maintained alignment, large surface area and good electrical conductivity, which leading to the formation of Pt particles with a smaller size and enhance the Pt utilization rate. The structure and nature of resulting Pt/VACNTs/CFP catalysts for methanol oxidation are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). With the aid of VACNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway, which leads to enhance the catalytic activity and Pt utilization rate. Compared with the Pt/XC-72/CFP electrode, the electrochemical measurements results display that the Pt/VACNTs/CFP catalyst shows much higher electrocatalytic activity and better stability for methanol oxidation. In addition, the oxidation current from 200 to 1200 s decayed more slowly for the Pt/VACNTs/CFP than that of the Pt/XC-72/CFP catalysts, indicating less accumulation of adsorbed CO species. All those results imply that the Pt/VACNTs/CFP has a great potential for applications in DMFCs.

Efficient and Anisotropic Fog Harvesting on a Hybrid and Directional Surface

KAUST Repository

Wu, Jinbo

2016-12-05

A straight throughout superhydrophilic track that contains high contrast and directional wettability on a superhydrophobic surface is designed. Despite droplets that tend to slide more easily along a direction parallel to the track, it is found that such hybrid strip-pattern surfaces have higher fog harvesting efficiency along a direction perpendicular to the tracks due to the larger accumulation area for droplet removal.

Renewable hydrogen utilisation for the production of methanol

International Nuclear Information System (INIS)

Galindo Cifre, P.; Badr, O.

2007-01-01

Electrolytic hydrogen production is an efficient way of storing renewable energy generated electricity and securing the contribution of renewables in the future electricity supply. The use of this hydrogen for the production of methanol results in a liquid fuel that can be utilised directly with minor changes in the existing infrastructure. To utilise the renewable generated hydrogen for production of renewable methanol, a sustainable carbon source is needed. This carbon can be provided by biomass or CO 2 in the flue gases of fossil fuel-fired power stations, cement factories, fermentation processes and water purification plants. Methanol production pathways via biomass gasification and CO 2 recovery from the flue gasses of a fossil fuel-fired power station have been reviewed in this study. The cost of methanol production from biomass was found to lie in the range of 300-400 EUR/tonne of methanol, and the production cost of CO 2 based methanol was between 500 and 600 EUR/tonne. Despite the higher production costs compared with methanol produced by conventional natural gas reforming (i.e. 100-200 EUR/tonne, aided by the low current price of natural gas), these new processes incorporate environmentally beneficial aspects that have to be taken into account. (author)

Directional genomic hybridization for chromosomal inversion discovery and detection.

Science.gov (United States)

Ray, F Andrew; Zimmerman, Erin; Robinson, Bruce; Cornforth, Michael N; Bedford, Joel S; Goodwin, Edwin H; Bailey, Susan M

2013-04-01

Chromosomal rearrangements are a source of structural variation within the genome that figure prominently in human disease, where the importance of translocations and deletions is well recognized. In principle, inversions-reversals in the orientation of DNA sequences within a chromosome-should have similar detrimental potential. However, the study of inversions has been hampered by traditional approaches used for their detection, which are not particularly robust. Even with significant advances in whole genome approaches, changes in the absolute orientation of DNA remain difficult to detect routinely. Consequently, our understanding of inversions is still surprisingly limited, as is our appreciation for their frequency and involvement in human disease. Here, we introduce the directional genomic hybridization methodology of chromatid painting-a whole new way of looking at structural features of the genome-that can be employed with high resolution on a cell-by-cell basis, and demonstrate its basic capabilities for genome-wide discovery and targeted detection of inversions. Bioinformatics enabled development of sequence- and strand-specific directional probe sets, which when coupled with single-stranded hybridization, greatly improved the resolution and ease of inversion detection. We highlight examples of the far-ranging applicability of this cytogenomics-based approach, which include confirmation of the alignment of the human genome database and evidence that individuals themselves share similar sequence directionality, as well as use in comparative and evolutionary studies for any species whose genome has been sequenced. In addition to applications related to basic mechanistic studies, the information obtainable with strand-specific hybridization strategies may ultimately enable novel gene discovery, thereby benefitting the diagnosis and treatment of a variety of human disease states and disorders including cancer, autism, and idiopathic infertility.

Effect of microchannel structure on the reaction performance of methanol steam reforming

International Nuclear Information System (INIS)

Pan, Minqiang; Wu, Qiuyu; Jiang, Lianbo; Zeng, Dehuai

2015-01-01

Highlights: • Effect of microchannel cross-section and distribution on MSR are investigated. • Microchannel distribution shows much more influence on reaction performance. • SLDR and ELR with rectangular cross-section present better reaction performance. • DLSR and EUU with tooth cross-section have better reaction performance. • Equal-distribution of microchannels present the best reaction performance. - Abstract: Methanol steam reforming inside microchannel reactors is regarded as one of effective methods for supplying hydrogen for fuel cells. Microchannel structure plays an important role on the reaction performance of methanol steam reforming. Parallel and uniform-distributed microchannels with rectangular cross-section are generally adopted. In this work, two kinds of microchannel cross-sections and four kinds of microchannel distributions are selected to investigate the effect of microchannel structure on the reaction performance of methanol steam reforming. The result indicates that microchannel distribution shows much more influences on the reaction performance of methanol steam reforming than the microchannel cross-section. Sparse-distribution in the Left direction and Dense-distribution in the Right direction (SLDR) as well as Equal-distribution in the Left–Right direction (ELR) with rectangular cross-section present relatively good reaction performances, whereas Dense-distribution in the Left direction and Sparse-distribution in the Right direction (DLSR) as well as Equal-distribution in the Upside–Underside direction (EUU) with tooth cross-section have relatively good performances. ELR presents the best reaction performances of methanol steam reforming among all the investigated microchannel structures, whether rectangular or tooth cross-section

A direct hybrid SN method for slab-geometry lattice calculations

International Nuclear Information System (INIS)

Silva, Davi J.M.; Barros, Ricardo C.; Zani, Jose H.

2011-01-01

In this work we describe a hybrid direct method for calculating the thermal disadvantage factor and the neutron flux distribution in fuel-moderator lattices. For the mathematical model, we use the one-speed slab-geometry discrete ordinates (S N ) transport equation with linearly anisotropic scattering. The basic idea is to use higher order angular quadrature set in the highly absorbing fuel region (S NF ) and lower order angular quadrature set in the diffusive moderator region (S NM ) , i.e., N F > N M . We apply special continuity conditions based on the equivalence of the S N and P N-1 equations, which characterize the hybrid model. Numerical results to a typical model problem are given to illustrate the accuracy and the efficiency of the offered hybrid method. (author)

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

Science.gov (United States)

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.; Lee, Sungsik; Flytzani-Stephanopoulos, Maria

2017-11-01

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid, which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. We find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolite-supported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. We anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful

Direct synthesis of bimetallic PtCo mesoporous nanospheres as efficient bifunctional electrocatalysts for both oxygen reduction reaction and methanol oxidation reaction

Science.gov (United States)

Wang, Hongjing; Yu, Hongjie; Li, Yinghao; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-04-01

The engineering of electrocatalysts with high performance for cathodic and/or anodic catalytic reactions is of great urgency for the development of direct methanol fuel cells. Pt-based bimetallic alloys have recently received considerable attention in the field of fuel cells because of their superior catalytic performance towards both fuel molecule electro-oxidation and oxygen reduction. In this work, bimetallic PtCo mesoporous nanospheres (PtCo MNs) with uniform size and morphology have been prepared by a one-step method with a high yield. The as-made PtCo MNs show superior catalytic activities for both oxygen reduction reaction and methanol oxidation reaction relative to Pt MNs and commercial Pt/C catalyst, attributed to their mesoporous structure and bimetallic composition.

Direct methanol fuel cell with extended reaction zone anode: PtRu and PtRuMo supported on graphite felt

Energy Technology Data Exchange (ETDEWEB)

Bauer, Alex; Gyenge, Elod L.; Oloman, Colin W. [Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC (Canada)

2007-05-15

Pressed graphite felt (thickness {proportional_to}350 {mu}m) with electrodeposited PtRu (43 g m{sup -2}, 1.4:1 atomic ratio) or PtRuMo (52 g m{sup -2}, 1:1:0.3 atomic ratio) nanoparticle catalysts was investigated as an anode for direct methanol fuel cells. At temperatures above 333 K the fuel cell performance of the PtRuMo catalyst was superior compared to PtRu. The power density was 2200 W m{sup -2} with PtRuMo at 5500 A m{sup -2} and 353 K while under the same conditions PtRu yielded 1925 W m{sup -2}. However, the degradation rate of the Mo containing catalyst formulation was higher. Compared to conventional gas diffusion electrodes with comparable PtRu catalyst composition and load, the graphite felt anodes gave higher power densities mainly due to the extended reaction zone for methanol oxidation. (author)

Direct methanol fuel cell with extended reaction zone anode: PtRu and PtRuMo supported on graphite felt

Science.gov (United States)

Bauer, Alex; Gyenge, Előd L.; Oloman, Colin W.

Pressed graphite felt (thickness ∼350 μm) with electrodeposited PtRu (43 g m -2, 1.4:1 atomic ratio) or PtRuMo (52 g m -2, 1:1:0.3 atomic ratio) nanoparticle catalysts was investigated as an anode for direct methanol fuel cells. At temperatures above 333 K the fuel cell performance of the PtRuMo catalyst was superior compared to PtRu. The power density was 2200 W m -2 with PtRuMo at 5500 A m -2 and 353 K while under the same conditions PtRu yielded 1925 W m -2. However, the degradation rate of the Mo containing catalyst formulation was higher. Compared to conventional gas diffusion electrodes with comparable PtRu catalyst composition and load, the graphite felt anodes gave higher power densities mainly due to the extended reaction zone for methanol oxidation.

Structure optimization of cathode microporous layer for direct methanol fuel cells

International Nuclear Information System (INIS)

Liu, Guicheng; Ding, Xianan; Zhou, Hongwei; Chen, Ming; Wang, Manxiang; Zhao, Zhenxuan; Yin, Zhuang; Wang, Xindong

2015-01-01

Highlights: • Pore-forming technology was introduced to optimize microporous layer microstructure. • The water removal and gas mass transfer property of diffusion layer were improved. • The optimum DMFC performance reached 292 mW cm −2 at 80 °C. - Abstract: To obtain the cathode microporous layer (CML) with high mass transfer performance and high electronic conductivity, a pore-forming technology was introduced to optimize CML microstructure for direct methanol fuel cells. In this paper, the effects of carbon material type, carbon material loading and pore-forming agent loading in CML on fuel cell performance were discussed systematically. The results indicated that the optimized CML consisted of carbon nanotubes and ammonium oxalate with the loading of 1.5 and 3.5 mg cm −2 respectively. The fuel cell performance was improved by 30.3%, from 224 to 292 mW cm −2 at 80 °C under 0.3 MPa O 2 . Carbon nanotube was found to be the most suitable carbon material for the CML due to its great specific surface area and small particle size, resulting in increasing the number of the hydrophobic sites and the contact area between the support and the catalyst layer. The carbon material and pore-forming agent loading directly influenced the pore distribution and the contact resistance of membrane electrode assembly. The water removal capacity and the gas mass transfer property of diffusion layer were improved by optimizing the amount of micropore and macropore structures

1995 world methanol conference

International Nuclear Information System (INIS)

Anon.

1995-01-01

The 20 papers contained in this volume deal with the global markets for methanol, the production of MTBE, integrating methanol production into a coal-to-SNG complex, production of methanol from natural gas, catalysts for methanol production from various synthesis gases, combined cycle power plants using methanol as fuel, and economics of the methanol industry. All papers have been processed for inclusion on the data base

Fabrication and Characterization of New Composite Tio2 Carbon Nanofiber Anodic Catalyst Support for Direct Methanol Fuel Cell via Electrospinning Method

Science.gov (United States)

Abdullah, N.; Kamarudin, S. K.; Shyuan, L. K.; Karim, N. A.

2017-12-01

Platinum (Pt) is the common catalyst used in a direct methanol fuel cell (DMFC). However, Pt can lead towards catalyst poisoning by carbonaceous species, thus reduces the performance of DMFC. Thus, this study focuses on the fabrication of a new composite TiO2 carbon nanofiber anodic catalyst support for direct methanol fuel cells (DMFCs) via electrospinning technique. The distance between the tip and the collector (DTC) and the flow rate were examined as influencing parameters in the electrospinning technique. To ensure that the best catalytic material is fabricated, the nanofiber underwent several characterizations and electrochemical tests, including FTIR, XRD, FESEM, TEM, and cyclic voltammetry. The results show that D18, fabricated with a flow rate of 0.1 mLhr-1 and DTC of 18 cm, is an ultrafine nanofiber with the smallest average diameter, 136.73 ± 39.56 nm. It presented the highest catalyst activity and electrochemical active surface area value as 274.72 mAmg-1 and 226.75m2 g-1 PtRu, respectively, compared with the other samples.

Kinetics of toluene alkylation with methanol catalyzed by pure and hybridized HZSM-5 catalysts

KAUST Repository

Alabi, Wahab

2012-07-01

A kinetic study of toluene alkylation with methanol was performed over pure HZSM-5, mordenite/ZSM-5 (hybrid of mordenite and HZSM-5), and ZM13 (composite mixture of HZSM-5 and MCM-41 at pH 13). Experimental runs were conducted using a batch fluidized bed reactor at temperatures of 300, 350 and 400 °C and reaction times of 3, 5, 7, 10, 13, 15 and 20. s. The rate of toluene methylation and toluene disproportionation were studied on the three catalysts (toluene alkylation is usually accompanied by toluene disproportionation on acid catalyst). Based on the results obtained, a simplified power law kinetic model consisting of three reactions was developed to estimate the activation energies of toluene methylation and disproportionation simultaneously. Coke formation on catalysts was accounted for using both reaction time and reactant conversion decay functions. All parameters were estimated based on quasi-steady state approximation. Estimated kinetic parameters were in good agreement with experimental results. The order of alkylation ability of the catalysts was found to be ZM13 > HZSM-5 > mordenite/ZSM-5, while the reverse is for toluene disproportionation (mordenite/ZSM-5 > HZSM-5 > ZM13). Thus, alkylation of toluene is most favorable on ZM13 due to combined effect of mesoporosity induced through its synthetic route and acid content. Toluene/MeOH molar ratio of 1:1 was most suitable for toluene alkylation reaction. © 2012 Elsevier B.V.

Towards a methanol economy based on homogeneous catalysis: methanol to H2 and CO2 to methanol

DEFF Research Database (Denmark)

Alberico, E.; Nielsen, Martin

2015-01-01

The possibility to implement both the exhaustive dehydrogenation of aqueous methanol to hydrogen and CO2 and the reverse reaction, the hydrogenation of CO2 to methanol and water, may pave the way to a methanol based economy as part of a promising renewable energy system. Recently, homogeneous...

Vapor-fed bio-hybrid fuel cell.

Science.gov (United States)

Benyamin, Marcus S; Jahnke, Justin P; Mackie, David M

2017-01-01

Concentration and purification of ethanol and other biofuels from fermentations are energy-intensive processes, with amplified costs at smaller scales. To circumvent the need for these processes, and to potentially reduce transportation costs as well, we have previously investigated bio-hybrid fuel cells (FCs), in which a fermentation and FC are closely coupled. However, long-term operation requires strictly preventing the fermentation and FC from harming each other. We introduce here the concept of the vapor-fed bio-hybrid FC as a means of continuously extracting power from ongoing fermentations at ambient conditions. By bubbling a carrier gas (N 2 ) through a yeast fermentation and then through a direct ethanol FC, we protect the FC anode from the catalyst poisons in the fermentation (which are non-volatile), and also protect the yeast from harmful FC products (notably acetic acid) and from build-up of ethanol. Since vapor-fed direct ethanol FCs at ambient conditions have never been systematically characterized (in contrast to vapor-fed direct methanol FCs), we first assess the effects on output power and conversion efficiency of ethanol concentration, vapor flow rate, and FC voltage. The results fit a continuous stirred-tank reactor model. Over a wide range of ethanol partial pressures (2-8 mmHg), power densities are comparable to those for liquid-fed direct ethanol FCs at the same temperature, with power densities >2 mW/cm 2 obtained. We then demonstrate the continuous operation of a vapor-fed bio-hybrid FC with fermentation for 5 months, with no indication of performance degradation due to poisoning (of either the FC or the fermentation). It is further shown that the system is stable, recovering quickly from disturbances or from interruptions in maintenance. The vapor-fed bio-hybrid FC enables extraction of power from dilute bio-ethanol streams without costly concentration and purification steps. The concept should be scalable to both large and small

Development of CH{sub 3}OH fueled PEMFC power plants for hybrid transit buses

Energy Technology Data Exchange (ETDEWEB)

Baumert, R; Cooper, R; Feasey, G [DBB Fuel Cell Engines Corp., Poway, CA (United States)

1999-12-31

An overview of the methanol fuel cell power system was provided, identifying improved efficiency and reduced emissions as the principal advantages. Four critical tasks regarding on-board fuel processing were described: (1) efficient methanol conversion (steam reforming), (2) effective reformate purification (selective catalytic oxidation), (3) optimized heat integration, and (4) rapid response to transients. A description of a 100 kW PEM fuel cell bus engine package was also presented. As far as a development time table is concerned, the DBB Fuel Cell Engines Corp. of Poway California has completed two methanol fueled PEMFC power plants, fabrication of the initial 100 kW PEMFC engine is in progress and scheduled for delivery by 1998. The two methanol fueled commercial products which are in the planning stages are the 100 and 200 kW class FCPS for hybrid and non-hybrid buses and other applications. tabs., figs.

Vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters

International Nuclear Information System (INIS)

Ahmed, Musahid; Ahmed, Musahid; Wilson, Kevin R.; Belau, Leonid; Kostko, Oleg

2008-01-01

In this work we report on the vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuum ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of the form (CH3OH)nH + (n=1-12) dominate the mass spectrum below the ionization energy of the methanol monomer. With an increase in water concentration, small amounts of mixed clusters of the form (CH3OH)n(H2O)H + (n=2-11) are detected. The only unprotonated species observed in this work are the methanol monomer and dimer. Appearance energies are obtained from the photoionization efficiency (PIE) curves for CH3OH +, (CH 3OH)2 +, (CH3OH)nH + (n=1-9), and (CH 3OH)n(H2O)H + (n=2-9 ) as a function of photon energy. With an increase in the water content in the molecular beam, there is an enhancement of photoionization intensity for methanol dimer and protonated methanol monomer at threshold. These results are compared and contrasted to previous experimental observations

Evidence for Conversion of Methanol to Formaldehyde in Nonhuman Primate Brain.

Science.gov (United States)

Zhai, Rongwei; Zheng, Na; Rizak, Joshua; Hu, Xintian

2016-01-01

Many studies have reported that methanol toxicity to primates is mainly associated with its metabolites, formaldehyde (FA) and formic acid. While methanol metabolism and toxicology have been best studied in peripheral organs, little study has focused on the brain and no study has reported experimental evidence that demonstrates transformation of methanol into FA in the primate brain. In this study, three rhesus macaques were given a single intracerebroventricular injection of methanol to investigate whether a metabolic process of methanol to FA occurs in nonhuman primate brain. Levels of FA in cerebrospinal fluid (CSF) were then assessed at different time points. A significant increase of FA levels was found at the 18th hour following a methanol injection. Moreover, the FA level returned to a normal physiological level at the 30th hour after the injection. These findings provide direct evidence that methanol is oxidized to FA in nonhuman primate brain and that a portion of the FA generated is released out of the brain cells. This study suggests that FA is produced from methanol metabolic processes in the nonhuman primate brain and that FA may play a significant role in methanol neurotoxicology.

Experimental Investigation of a Direct Methanol Fuel Cell with Hilbert Fractal Current Collectors

Directory of Open Access Journals (Sweden)

Jing-Yi Chang

2014-01-01

Full Text Available The Hilbert curve is a continuous type of fractal space-filling curve. This fractal curve visits every point in a square grid with a size of 2×2, 4×4, or any other power of two. This paper presents Hilbert fractal curve application to direct methanol fuel cell (DMFC current collectors. The current collectors are carved following first, second, and third order Hilbert fractal curves. These curves give the current collectors different free open ratios and opening perimeters. We conducted an experimental investigation into DMFC performance as a function of the free open ratio and opening perimeter on the bipolar plates. Nyquist plots of the bipolar plates are made and compared using electrochemical impedance spectroscopy (EIS experiments to understand the phenomena in depth. The results obtained in this paper could be a good reference for future current collector design.

Utilization of methanol plus hydrogen by Methanosarcina barkeri for methanogenesis and growth

International Nuclear Information System (INIS)

Mueller, V.; Blaut, M.; Gottschalk, G.

1986-01-01

Methanosarcina barkeri grew on methanol plus H 2 . Both substrates were consumed in equimolar amounts. Growth was strictly dependently on the presence of acetate, which was required for the biosynthesis of cellular constituents. Only about 0.4% of the methane produced originated from acetate. By using deuterated methanol, it was demonstrated that methanogenesis from this compound under H 2 did not occur via oxidation of methanol to CO 2 and subsequent reduction but by direct reduction with H 2 . Growth yields with methanol plus H 2 and with methanol alone were not significantly different: 2.8 g of cells per mol of methanol in mineral medium and 4.6 g of cells per mol of methanol in complex medium, respectively. Growth of M. barkeri on methanol plus H 2 depended strictly on the presence of sodium ions in the medium. In the presence of 50 mM K + the K/sub s/ for Na + was 5 mM

Injector spray characterization of methanol in reciprocating engines

Science.gov (United States)

Dodge, L.; Naegeli, D.

1994-06-01

This report covers a study that addressed cold-starting problems in alcohol-fueled, spark-ignition engines by using fine-spray port-fuel injectors to inject fuel directly into the cylinder. This task included development and characterization of some very fine-spray, port-fuel injectors for a methanol-fueled spark-ignition engine. After determining the spray characteristics, a computational study was performed to estimate the evaporation rate of the methanol fuel spray under cold-starting and steady-state conditions.

The (p, ρ, T) of (methanol + benzene) and (methanol + ethylbenzene)

International Nuclear Information System (INIS)

Naziev, Yashar M.; Shahverdiyev, Astan N.; Hasanov, Vaqif H.

2005-01-01

The (p, ρ, T) of methanol, ethylbenzene and (methanol + benzene) and (methanol + ethylbenzene) at temperatures between (290 and 500) K and pressures in the range (0.1 to 60) MPa have been measured with a magnetic suspension densimeter with an uncertainty of ±0.1%. Our measurements with methanol deviate from the literature values by less than 0.2%. The (p, ρ, T) measurements were fitted with experimental uncertainties by an empirical equation. The temperature and mole fraction dependence of the coefficients of the equation of state are presented

Enhanced methanol electro-oxidation reaction on Pt-CoO{sub x}/MWCNTs hybrid electro-catalyst

Energy Technology Data Exchange (ETDEWEB)

Nouralishahi, Amideddin, E-mail: Nouralishahi@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Caspian Faculty of Engineering, University of Tehran, P.O. Box 43841-119, Rezvanshahr (Iran, Islamic Republic of); Catalysis and Nanotechnology Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Rashidi, Ali Morad, E-mail: Rashidiam@ripi.ir [Catalysis and Nanotechnology Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Mortazavi, Yadollah, E-mail: Mortazav@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Khodadadi, Abbas Ali, E-mail: Khodadad@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Choolaei, Mohammadmehdi, E-mail: Choolaeimm@ripi.ir [Catalysis and Nanotechnology Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of)

2015-04-30

Highlights: • Promoting effects of Cobalt oxide on methanol electro-oxidation over Pt/MWCNTs are investigated. • Higher activity, about 2.9 times, and enhanced stability are observed on Pt-CoO{sub x}/MWCNTs. • Electrochemical active surface area of Pt nanoparticles is significantly improved upon CoO{sub x} addition. • Bi-functional mechanism is facilitated in presence of CoO{sub x}. - Abstract: The electro-catalytic behavior of Pt-CoO{sub x}/MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH{sub 4} as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoO{sub x}, Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of CO{sub ads} on Pt active sites by the participation of CoO{sub x}. Compared to Pt/MWCNTs, Pt-CoO{sub x}/MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoO{sub x}/MWCNTs, at small overpotentials. However, at higher overpotentials, the

One-dimensional hybrid-direct kinetic simulation of the discharge plasma in a Hall thruster

International Nuclear Information System (INIS)

Hara, Kentaro; Boyd, Iain D.; Kolobov, Vladimir I.

2012-01-01

In order to model the non-equilibrium plasma within the discharge region of a Hall thruster, the velocity distribution functions (VDFs) must be obtained accurately. A direct kinetic (DK) simulation method that directly solves the plasma Boltzmann equation can achieve better resolution of VDFs in comparison to particle simulations, such as the particle-in-cell (PIC) method that inherently include statistical noise. In this paper, a one-dimensional hybrid-DK simulation, which uses a DK simulation for heavy species and a fluid model for electrons, is developed and compared to a hybrid-PIC simulation. Time-averaged results obtained from the hybrid-DK simulation are in good agreement with hybrid-PIC results and experimental data. It is shown from a comparison of using a kinetic simulation and solving the continuity equation that modeling of the neutral atoms plays an important role for simulations of the Hall thruster discharge plasma. In addition, low and high frequency plasma oscillations are observed. Although the kinetic nature of electrons is not resolved due to the use of a fluid model, the hybrid-DK model provides spatially and temporally well-resolved plasma properties and an improved resolution of VDFs for heavy species with less statistical noise in comparison to the hybrid-PIC method.

Gas chromatography/isotope ratio mass spectrometry: analysis of methanol, ethanol and acetic acid by direct injection of aqueous alcoholic and acetic acid samples.

Science.gov (United States)

Ai, Guomin; Sun, Tong; Dong, Xiuzhu

2014-08-15

Methanol, ethanol, and acetic acid are not easily extracted from aqueous samples and are susceptible to isotope fractionation in gas chromatography/isotope ratio mass spectrometry (GC/IRMS) analysis. Developing a direct dilution GC/IRMS method for aqueous samples, by adjusting the sample concentrations in common solvents to be similar to each other and using a fixed GC split ratio, is very convenient and important because any linearity effects caused by amount-dependent isotope fractionation can be avoided. The suitability of acetonitrile and acetone solvents for the GC/IRMS analysis of pure methanol, ethanol and acetic acid, and commercial liquor and vinegar samples was evaluated using n-hexane and water as control solvents. All the solvents including water were separated from the analyte on a HP-INNOWAX column and were diverted away from the combustion interface. The influence of liquor matrix on the ethanol GC/IRMS analyses was evaluated by adding pure ethanol to liquor samples. Acetonitrile and acetone gave similar δ(13) C values for pure ethanol and pure acetic acid to those obtained in water and n-hexane, and also gave similar δ(13) C values of ethanol in liquor and acetic acid in white vinegar to that obtained in water. For methanol analysis, acetonitrile and refined acetone gave similar δ(13) C values to that obtained in water, but n-hexane was not a suitable solvent. In addition, isotopic fractionation caused by solvent and solute interactions was observed. We recommend using acetonitrile for the GC/IRMS analysis of aqueous alcoholic samples, and acetone for the analysis of aqueous acetic acid samples. This direct dilution method can provide high accurate and precise GC/IRMS analysis of the relative changes in δ(13) C values of methanol, ethanol, and acetic acid. Copyright © 2014 John Wiley & Sons, Ltd.

Methanol Fuel Cell

Science.gov (United States)

Voecks, G. E.

1985-01-01

In proposed fuel-cell system, methanol converted to hydrogen in two places. External fuel processor converts only part of methanol. Remaining methanol converted in fuel cell itself, in reaction at anode. As result, size of fuel processor reduced, system efficiency increased, and cost lowered.

Observation of methanol behavior in fuel cells in situ by NMR spectroscopy.

Science.gov (United States)

Han, Oc Hee; Han, Kee Sung; Shin, Chang Woo; Lee, Juhee; Kim, Seong-Soo; Um, Myung Sup; Joh, Han-Ik; Kim, Soo-Kil; Ha, Heung Yong

2012-04-16

The chemical conversion of methanol in direct methanol fuel cells was followed in situ by NMR spectroscopy. Comparing data of the methanol oxidation on Pt and PtRu anode catalysts allowed the role of Ru in both Faradaic and non-Faradaic reactions to be investigated. The spatial distributions of chemicals could also be determined. (Picture: T1-T4=inlet and outlet tubes.). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fusion-fission hybrid design with analysis of direct enrichment and non-proliferation features (the SOLASE-H study)

International Nuclear Information System (INIS)

Conn, R.W.; Abdel-Khalik, S.I.; Moses, G.A.; Kulcinski, G.L.; Larsen, E.; Maynard, C.W.; Magheb, M.M.H.; Sviatolslavsky, I.N.; Vogelsang, W.F.; Wolfer, W.G.

1981-01-01

The role of a fusion-fission hybrid in the context of a nuclear economy with and without reprocessing is examined. An inertial confinement fusion driver is assumed and a consistent set of reactor parameters are developed. The form of the driver is not critical, however, to the general concepts. The use of the hybrid as a fuel factory within a secured fuel production and reprocessing center is considered. Either the hybrid or a low power fission reactor can be used to mildly irradiate fuel prior to shipment to offsite reactors thereby rendering the fuel resistant to diversion. A simplified economic analysis indicates a hybrid providing fuel to 10 fission reactors of equal thermal power is insensitive to the recirculating power fraction provided reprocessing is permitted. If reprocessing is not allowed, the hybrid can be used to directly enrich light water reactor fuel bundles fabricated initially from fertile fuel (either ThO 2 or 238 UO 2 ). A detailed neutronic analysis indicates such direct enrichments is feasible but the support ratio for 233 U or 239 Pu production is only 2, making such an approach highly sensitive to the hybrid cost. The hybrid would have to produce considerable net power for economic feasibility in this case. Inertial confinement fusion performance requirements for hybrid application are also examined and an integrated design, SOLASE-H, is described based upon the direct enrichment concept. (orig.)

Biodiesel production from Spirulina microalgae feedstock using direct transesterification near supercritical methanol condition.

Science.gov (United States)

Mohamadzadeh Shirazi, Hamed; Karimi-Sabet, Javad; Ghotbi, Cyrus

2017-09-01

Microalgae as a candidate for production of biodiesel, possesses a hard cell wall that prevents intracellular lipids leaving out from the cells. Direct or in situ supercritical transesterification has the potential for destruction of microalgae hard cell wall and conversion of extracted lipids to biodiesel that consequently reduces the total energy consumption. Response surface methodology combined with central composite design was applied to investigate process parameters including: Temperature, Time, Methanol-to-dry algae, Hexane-to-dry algae, and Moisture content. Thirty-two experiments were designed and performed in a batch reactor, and biodiesel efficiency between 0.44% and 99.32% was obtained. According to fatty acid methyl ester yields, a quadratic experimental model was adjusted and the significance of parameters was evaluated using analysis of variance (ANOVA). Effects of single and interaction parameters were also interpreted. In addition, the effect of supercritical process on the ultrastructure of microalgae cell wall using scanning electron spectrometry (SEM) was surveyed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Direct Evidence for Maser Emission from the 36.2 GHz Class I Transition of Methanol in NGC253

Science.gov (United States)

Chen, Xi; Ellingsen, Simon P.; Shen, Zhi-Qiang; McCarthy, Tiege P.; Zhong, Wei-Ye; Deng, Hui

2018-04-01

Observations made with the Jansky Very large Array (JVLA) at an angular resolution of ∼0.″1 have detected class I methanol maser emission from the 36.2 GHz transition toward the starburst galaxy NGC 253. The methanol emission is detected toward four sites which lie within the regions of extended methanol emission detected in previous lower angular resolution (a few arcseconds) observations. The peak flux densities of the detected compact components are in the range 3–9 mJy beam‑1. Combining the JVLA data with single-dish observations from the Shanghai Tianma Radio Telescope (TMRT) and previous interferometric observations with the Australia Telescope Compact Array (ATCA), we show that the 36.2 GHz class I methanol emission consists of both extended and compact structures, with typical scales of ∼6″ (0.1 kpc) and ∼0.″05 (1 pc), respectively. The strongest components have a brightness temperature of >103 K, much higher than the maximum kinetic temperature (∼100 K) of the thermal methanol emission from NGC 253. Therefore, these observations conclusively demonstrate for the first time the presence of maser emission from a class I methanol transition in an external galaxy.

An in-situ nano-scale swelling-filling strategy to improve overall performance of Nafion membrane for direct methanol fuel cell application

Science.gov (United States)

Li, Jing; Fan, Kun; Cai, Weiwei; Ma, Liying; Xu, Guoxiao; Xu, Sen; Ma, Liang; Cheng, Hansong

2016-11-01

A novel in-situ nano-scale swelling-filling (SF) strategy is proposed to modify commercial Nafion membranes for performance enhancement of direct methanol fuel cells (DMFCs). A Nafion membrane was filled in-situ with proton conductive macromolecules (PCMs) in the swelling process of a Nafion membrane in a PCM solution. As a result, both proton conductivity and methanol-permeation resistivity of the SF-treated Naifion membrane was substantially improved with the selectivity nearly doubled compared to the original Nafion membrane. The mechanical strength of the optimal SF treated Nafion membrane was also enforced due to the strong interaction between the PCM fillers and the Nafion molecular chains. As a result, a DMFC equipped with the SF-treated membrane yielded a 33% higher maximum power density than that offered by the DMFC with the original Nafion membrane.

EFFECT OF STARCH ADDITION ON THE PERFORMANCE AND SLUDGE CHARACTERIZATION OF UASB PROCESS TREATING METHANOLIC WASTEWATER

Science.gov (United States)

Yan, Feng; Kobayashi, Takuro; Takahashi, Shintaro; Li, Yu-You; Omura, Tatsuo

A mesophilic(35℃) UASB reactor treating synthetic wastewater containing methanol with addition of starch was continuously operated for over 430 days by changing the organic loading rate from 2.5 to 120kg-COD/m3.d. The microbial community structure of the granules was analyzed with the molecular tools and its metabolic characteristics were evaluated using specific methanogenic activity tests. The process was successfully operated with over 98% soluble COD removal efficiency at VLR 30kg-COD/m3.d for approximately 300 days, and granulation satisfactory proceeded. The results of cloning and fluorescence in situ hybridization analysis suggest that groups related the genus Methanomethylovorans and the genus Methanosaeta were predominant in the reactor although only the genus Methanomethylovorans was predominant in the reactor treating methanolic wastewater in the previous study. Abundance of the granules over 0.5 mm in diameter in the reactor treating methanolic wastewater with addition of starch was 3 times larger than that in the reactor treating methanolic wastewater. Specific methanogenic activity tests in this study indicate that the methanol-methane pathway and the methanol-H2/CO2-methane pathway were predominant, and however, there was a certain level of activity for acetate-methane pathway unlike the reactor treating methanolic wastewater. These results suggest addition of starch might be responsible for diversifying the microbial community and encouraging the granulation.

Partial sulfonation of PVdF-co-HFP: A preliminary study and characterization for application in direct methanol fuel cell

International Nuclear Information System (INIS)

Das, Suparna; Kumar, Piyush; Dutta, Kingshuk; Kundu, Patit Paban

2014-01-01

Highlights: • Synthesis of sulfonated PVdF-co-HFP by reacting with chlorosulfonic acid. • Maximum degree of sulfonation and best properties were obtained for 7 h reaction. • A maximum water uptake value of 20% was obtained. • A maximum IEC value of 0.42 meq g −1 was obtained. • A methanol permeability of 2.44 × 10 −7 cm 2 s −1 was obtained. - Abstract: Sulfonation of PVdF-co-HFP was conducted by treating the copolymer with chlorosulfonic acid. The efficiency of this sulfonated copolymer towards application as a polymer electrolyte membrane in direct methanol fuel cell (DMFC) was evaluated. For this purpose, we determined the thermal stability, water uptake, ion exchange capacity (IEC), methanol crossover, and proton conductivity of the prepared membranes as functions of duration and degree of sulfonation. The characteristic aromatic peaks obtained in the FT-IR spectra confirmed the successful sulfonation of PVdF-co-HFP. The effect of sulfonation on the semi-crystalline nature of pure PVdF-co-HFP was determined from XRD analysis. Water uptake results indicated that a sulfonation time of 7 h produced maximum water uptake value of about 20%, with a corresponding IEC and proton conductivity values of about 0.42 meq g −1 and 0.00375 S cm −1 respectively. The maximum current density was recorded to be 30 mA cm −2 at 0.2 V potential

Methanol fuel update

International Nuclear Information System (INIS)

Colledge, R.; Spacek, J.

1992-01-01

An overview is presented of methanol fuel developments, with particular reference to infrastructure, supply and marketing. Methanol offers reduced emissions, easy handling, is cost effective, can be produced from natural gas, coal, wood, or municipal waste, is a high performance fuel, is safer than gasoline, and contributes to energy security. Methanol supply, environmental benefits, safety/health issues, economics, passenger car economics, status of passenger car technology, buses, methanol and the prosperity initiative, challenges to implementation, and the role of government and original equipment manufacturers are discussed. Governments must assist in the provision of methanol refuelling infrastructure, and in providing an encouraging regulatory atmosphere. Discriminatory and inequitable taxing methods must be addressed, and an air quality agenda must be defined to allow the alternative fuel industry to respond in a timely manner

Integrated methanol synthesis

International Nuclear Information System (INIS)

Jaeger, W.

1982-01-01

This invention concerns a plant for methanol manufacture from gasified coal, particularly using nuclear power. In order to reduce the cost of the hydrogen circuits, the methanol synthesis is integrated in the coal gasification plant. The coal used is gasified with hydration by means of hydrogen and the crude gas emerging, after cooling and separating the carbon dioxide and hydrogen sulphide, is mixed with the synthetic gas leaving the methane cracking furnace. This mixture is taken to the methanol synthesis and more than 90% is converted into methanol in one pass. The gas mixture remaning after condensation and separation of methanol is decomposed into three fractions in low temperature gas decomposition with a high proportion of unconverted carbon monoxide. The flow of methane is taken to the cracking furnace with steam, the flow of hydrogen is taken to the hydrating coal gasifier, and the flow of carbon monoxide is taken to the methanol synthesis. The heat required for cracking the methane can either be provided by a nuclear reactor or by the coke left after hydrating gasification. (orig./RB) [de

Ru-decorated Pt nanoparticles on N-doped multi-walled carbon nanotubes by atomic layer deposition for direct methanol fuel cells

DEFF Research Database (Denmark)

Johansson, Anne-Charlotte Elisabeth Birgitta; Yang, R.B.; Haugshøj, K.B.

2013-01-01

We present atomic layer deposition (ALD) as a new method for the preparation of highly dispersed Ru-decorated Pt nanoparticles for use as catalyst in direct methanol fuel cells (DMFCs). The nanoparticles were deposited onto N-doped multi-walled carbon nanotubes (MWCNTs) at 250 °C using trimethyl......(methylcyclopentadienyl)platinum MeCpPtMe3, bis(ethylcyclopentadienyl)ruthenium Ru(EtCp)2 and O2 as the precursors. Catalysts with 5, 10 and 20 ALD Ru cycles grown onto the CNT-supported ALD Pt nanoparticles (150 cycles) were prepared and tested towards the electro-oxidation of CO and methanol, using cyclic voltammetry...... and chronoamperometry in a three-electrode electrochemical set-up. The catalyst decorated with 5 ALD Ru cycles was of highest activity in both reactions, followed by the ones with 10 and 20 ALD Ru cycles. It is demonstrated that ALD is a promising technique in the field of catalysis as highly dispersed nanoparticles...

Methanol sensor for integration with GaP nanowire photocathode

Science.gov (United States)

Novák, J.; Laurenčíková, A.; Hasenohrl, S.; Eliáš, P.; Kováč, J.

2017-05-01

We proposed a new type of the methanol concentration sensor that may be integrated directly to the GaP nanostructured photocathode. Necessary attribute for this design is the possibility to make it compatible with p-type of semiconductor. This condition follows from the fact that photocathodes for the CO2 splitting are exclusively prepared from p-type of semiconductors. Design of methanol sensor emanates from this principle. On the GaP substrate is deposited thin Pt supporting layer (100-200 nm thick).This layer is covered by 500 nm thick Nafion membrane that serves as proton filter. On the top of Nafion layer is deposited top Pt contact layer covered by thin nanostructured Pt layer layer with various thickness (0.5 -5 nm). This nanostructured Pt is formed into small islands. It serves as an absorption layer for methanol. Sensor detection properties were estimated from monitoring of I-V characteristics. They were measured in dark and under various methanol concentrations. Dark current values are in order 10-9 A, and this current increases up to order of microamps for methanol of concentration more than 95%.These measurements proved high sensitivity of the GaP compatible sensor structure. Methanol sensors were realized in form of narrow stripe on the side of the photocathode.

Direct deposition of inorganic–organic hybrid semiconductors and their template-assisted microstructures

International Nuclear Information System (INIS)

Dwivedi, V.K.; Baumberg, J.J.; Prakash, G. Vijaya

2013-01-01

A straight-forward method is developed to deposit a new class of self-organized inorganic–organic (IO) hybrid, (C 12 H 25 NH 3 ) 2 PbI 4 . These IO hybrid structures are stacked-up as natural multiple quantum well structures and exhibit strong room-temperature exciton emission and other multifunctional features. Here it is successfully demonstrated that these materials can be directly carved into 2D photonic structures from the inexpensive template-assisted electrochemical deposition followed by solution processing. The applicability of this method for many such varieties of IO-hybrids is also explored. By appropriately controlling the deposition conditions and the self-assembly templates, target structures are developed for new-generation low-cost photonic devices. -- Highlights: ► New fabrication methodology for self-organized inorganic–organic hybrids. ► Strongly confined exciton emission and photoconductive properties. ► Simple bottom-up fabrication for device applications.

Synthesis and properties of a novel sulfonated poly(arylene ether ketone sulfone) membrane with a high β-value for direct methanol fuel cell applications

International Nuclear Information System (INIS)

Xu, Jingmei; Ma, Li; Han, Hailan; Ni, Hongzhe; Wang, Zhe; Zhang, Huixuan

2014-01-01

Highlights: • Introduction of carboxyl groups into copolymers resulted in extensive hydrogen bond. • The C-SPAEKS membranes had obviously hydrophilic/hydrophobic phase separation. • The membranes showed low methanol permeability and high β values. • The membranes exhibited good thermal property and desirable mechanical performance. - Abstract: Sulfonated poly(arylene ether ketone sulfone) membranes containing carboxylic acid groups (C-SPAEKS) with different degrees of sulfonation were synthesized by the nucleophilic aromatic substitution reactions of 4-carboxylphenyl hydroquinone (4C-PH), bisphenol A, 3,3′-disulfonated 4,4′-dichlorodiphenyl sulfone, and 4,4′-difluorobenzophenone. The Fourier transform infrared and 1 H NMR analyses of C-SPAEKS revealed the presence of carboxylic acid groups in the C-SPAEKS membranes. The membranes exhibited a low swelling degree and methanol crossover level. The effects of different degrees of sulfonation on the water uptake, proton conductivity, and methanol permeability coefficient of the membranes were studied. The maximum proton conductivity of C-SPAEKS-80 membrane at room temperature was 0.069 S cm −1 , which was higher than that of Nafion ® 117 membrane. The methanol permeability coefficient of C-SPAEKS-80 membrane was 9.15 × 10 −7 cm 2 s −1 at 20 °C, much lower than that of Nafion 117 membrane (22.9 × 10 −7 cm 2 s −1 ). Furthermore, the carboxyl group-containing membranes exhibited a high β-value, further confirming that this series of membranes possess excellent comprehensive performance and can be applied in direct methanol fuel cells

Research Progress on the Indirect Hydrogenation of Carbon Dioxide to Methanol.

Science.gov (United States)

Du, Xian-Long; Jiang, Zheng; Su, Dang Sheng; Wang, Jian-Qiang

2016-02-19

Methanol is a sustainable source of liquid fuels and one of the most useful organic chemicals. To date, most of the work in this area has focused on the direct hydrogenation of CO2 to methanol. However, this process requires high operating temperatures (200-250 °C), which limits the theoretical yield of methanol. Thus, it is desirable to find a new strategy for the efficient conversion of CO2 to methanol at relatively low reaction temperatures. This Minireview seeks to outline the recent advances on the indirect hydrogenation of CO2 to methanol. Much emphasis is placed on discussing specific systems, including hydrogenation of CO2 derivatives (organic carbonates, carbamates, formates, cyclic carbonates, etc.) and cascade reactions, with the aim of critically highlighting both the achievements and remaining challenges associated with this field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improving the Durability of Methanol Oxidation Reaction Electro-Catalysts Through the Modification of Carbon Architectures

Science.gov (United States)

2014-01-01

PEMFC Direct Methanol Fuel Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DMFC Colorado School of Mines...Thus, a methanol-fed proton exchange membrane fuel cell ( PEMFC ) utilizing this potentially inexpensive fuel, would provide a sustainable and renewable

Liquid methanol under a static electric field

Energy Technology Data Exchange (ETDEWEB)

Cassone, Giuseppe, E-mail: giuseppe.cassone@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France); Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Giaquinta, Paolo V., E-mail: paolo.giaquinta@unime.it [Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); Saija, Franz, E-mail: saija@ipcf.cnr.it [CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Saitta, A. Marco, E-mail: marco.saitta@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France)

2015-02-07

We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm{sup −1}) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.

Development of a direct methanol fuel cell system for the power segment below 5 kW; Entwicklung eines Direkt-Methanol-Brennstoffzellensystems der Leistungsklasse kleiner 5 kW

Energy Technology Data Exchange (ETDEWEB)

Noelke, M.

2006-10-20

The attractiveness of electrical conversion of liquid methanol in a fuel cell is defined by its simple storage and high energy density. Therefore, direct-methanol fuel cell (DMFC) qualifies for applications in portable systems and mobile application in the kW-class. The goal of this work is to develop and demonstrate an improved and optimized peripheral DMFC system compared to the current level of technology. The selected mobile application is the retrofit of the energy supply of a ''Scooter'' with a fuel cell system. The required size reduction and the simplification of the DMFC system are realized by an integrated concept, which combines ideally the peripheral system and the fuel cell. A profound analysis of the stack and the peripheral components is a prerequisite for an optimized design. A detailed modelling and understanding of the stack behaviour establish the starting point of this work. The influence of the most important operating parameters like stack temperature, cell voltage, current density, air ratio and methanol concentration is captured accurately by the developed model and validated by experimental data. This shapes the frame work of the following system design approach. For this the clearly defined task of the peripheral system are investigated individually for alternatives and the best option is selected for the final solution. For selecting the right pumps and blowers available products and prototypes are characterized and checked for the system requirements. The investigation and the modelling of the exhaust gas condenser lead to an optimized component design for the ''Scooter'' DMFC design. Additionally, the integration of the anode loop is accomplished consisting of the supply lines, the circulating pump, the gas separator and the exhaust line. The direct coupling of the fuel cell with a lithium-ion battery as an option for electrical conditioning is investigated. In the system modelling the influence

Direct analysis of formate in human plasma, serum and whole blood by in-line coupling of microdialysis to capillary electrophoresis for rapid diagnosis of methanol poisoning

OpenAIRE

Kubáň, P. (Pavel); Boček, P. (Petr)

2013-01-01

A microdialytic device was in-line coupled to capillary electrophoresis for direct injection of blood samples. Its performance was demonstrated on rapid analysis of formic acid in various blood samples including serum samples of a patient diagnosed with acute methanol poisoning.

Short-term inhalation toxicity of methanol, gasoline, and methanol/gasoline in the rat.

Science.gov (United States)

Poon, R; Chu, I; Bjarnason, S; Vincent, R; Potvin, M; Miller, R B; Valli, V E

1995-01-01

Four- to five-week-old male and female Sprague Dawley rats were exposed to vapors of methanol (2500 ppm), gasoline (3200 ppm), and methanol/gasoline (2500/3200 ppm, 570/3200 ppm) six hours per day, five days per week for four weeks. Control animals were exposed to filtered room air only. Depression in body weight gain and reduced food consumption were observed in male rats, and increased relative liver weight was detected in rats of both sexes exposed to gasoline or methanol/gasoline mixtures. Rats of both sexes exposed to methanol/gasoline mixtures had increased relative kidney weight and females exposed to gasoline and methanol/gasoline mixtures had increased kidney weight. Decreased serum glucose and cholesterol were detected in male rats exposed to gasoline and methanol/gasoline mixtures. Decreased hemoglobin was observed in females inhaling vapors of gasoline and methanol/gasoline at 570/3200 ppm. Urine from rats inhaling gasoline or methanol/gasoline mixtures had up to a fourfold increase in hippuric acid, a biomarker of exposure to the toluene constituent of gasoline, and up to a sixfold elevation in ascorbic acid, a noninvasive biomarker of hepatic response. Hepatic mixed-function oxidase (aniline hydroxylase, aminopyrine N-demethylase and ethoxyresorufin O-deethylase) activities and UDP-glucuronosyltransferase activity were elevated in rats exposed to gasoline and methanol/gasoline mixtures. Histopathological changes were confined to very mild changes in the nasal passages and in the uterus, where decreased incidence or absence of mucosal and myometrial eosinophilia was observed in females inhaling gasoline and methanol/gasoline at 570/3200 ppm. It was concluded that gasoline was largely responsible for the adverse effects, the most significant of which included depression in weight gain in the males, increased liver weight and hepatic microsomal enzyme activities in both sexes, and suppression of uterine eosinophilia. No apparent interactive effects

A Fifth Order Hybrid Linear Multistep method For the Direct Solution ...

African Journals Online (AJOL)

A linear multistep hybrid method (LMHM)with continuous coefficients isconsidered and directly applied to solve third order initial and boundary value problems (IBVPs). The continuous method is used to obtain Multiple Finite Difference Methods (MFDMs) (each of order 5) which are combined as simultaneous numerical ...

Liquid-Feed Methanol Fuel Cell With Membrane Electrolyte

Science.gov (United States)

Surampudi, Subbarao; Narayanan, S. R.; Halpert, Gerald; Frank, Harvey; Vamos, Eugene

1995-01-01

Fuel cell generates electricity from direct liquid feed stream of methanol/water solution circulated in contact with anode, plus direct gaseous feed stream of air or oxygen in contact with cathode. Advantages include relative simplicity and elimination of corrosive electrolytic solutions. Offers potential for reductions in size, weight, and complexity, and for increases in safety of fuel-cell systems.

Covalent-ionically cross-linked polyetheretherketone proton exchange membrane for direct methanol fuel cell

CSIR Research Space (South Africa)

Luo, H

2010-08-01

Full Text Available cross-linked PEEK-WC membrane, this covalent-ionically cross-linked PEEK-WC membrane exhibits extremely reduced water uptake and methanol permeability, but just slightly sacrificed proton conductivity. The proton conductivity of the covalent...

Methanol exchange dynamics between a temperate cropland soil and the atmosphere

Science.gov (United States)

Bachy, A.; Aubinet, M.; Amelynck, C.; Schoon, N.; Bodson, B.; Moureaux, C.; Delaplace, P.; De Ligne, A.; Heinesch, B.

2018-03-01

Soil methanol (CH3OH) exchange is often considered as several orders of magnitude smaller than plant methanol exchange. However, for some ecosystems, it is significant in regard with plant exchange and worth thus better consideration. Our study sought to gain a better understanding of soil exchange. Methanol flux was measured at the ecosystem scale on a bare agricultural soil over two contrasted periods using the disjunct eddy covariance by mass scanning technique. A proton-transfer-reaction mass spectrometer was used for the methanol ambient mixing ratio measurements. Bi-directional exchange dynamics were observed. Methanol emission occurred under dry and warm conditions and correlated best with soil surface temperature, whereas methanol uptake occurred under wet and mild conditions and correlated well with the methanol ambient concentration. After having tested a physical adsorption-desorption model and by confronting our data with the literature, we propose that the exchange was ruled by both a physical adsorption/desorption mechanism and by a methanol source, which still needs to be identified. The soil emission decreased when the vegetation developed. The reasons for the decrease still need to be determined. Overall, the dynamics observed at our site were similar to those reported by other studies for both cropland and forest ecosystems. The mechanism proposed in our work can thus be possibly applied to other sites or ecosystems. In addition, the methanol exchange rate was in the upper range of the exchange rates reported by other soil studies, suggesting that cropland soils are more important methanol exchangers than those in other ecosystems and should therefore be further investigated.

Electro-catalytic biodiesel production from canola oil in methanolic and ethanolic solutions with low cost stainless steel and hybrid ion-exchange resin grafted electrodes

Science.gov (United States)

Allioux, Francois-Marie; Holland, Brendan J.; Kong, Lingxue; Dumée, Ludovic F.

2017-07-01

Biodiesel is a growing alternative to petroleum fuels and is produced by the catalysed transesterification of fats in presence of an alcohol base. Transesterification processes using homogeneous catalysts are considered to be amongst the most efficient methods but rely on the feedstock quality and low water content in order to avoid undesirable saponification reactions. In this work, the electro-catalytic conversion of canola oil to biodiesel in a 1% aqueous methanolic and ethanolic reaction mixture was performed without the addition of external catalyst or co-solvent. An inexpensive stainless steel electrode and a hybrid stainless steel electrode coated with an ion-exchange resin catalyst were used as cathode materials while the anode was composed of a plain carbon paper. The cell voltages were varied from 10 to 40 V and the reaction temperature maintained at 20 or 40°C. The canola oil conversion rates were found to be superior at 40°C without saponification reactions for cell voltages below 30 V. The conversion rates were as high as 87% for the hybrid electrode and 81% for the plain stainless steel electrode. This work could inspire new process development for the conversion of high water content feedstock for the production of second-generation biodiesel.

Electro-Catalytic Biodiesel Production from Canola Oil in Methanolic and Ethanolic Solutions with Low-Cost Stainless Steel and Hybrid Ion-Exchange Resin Grafted Electrodes

Directory of Open Access Journals (Sweden)

Francois-Marie Allioux

2017-07-01

Full Text Available Biodiesel is a growing alternative to petroleum fuels and is produced by the catalyzed transesterification of fats in presence of an alcohol base. Transesterification processes using homogeneous catalysts are considered to be among the most efficient methods but rely on the feedstock quality and low water content in order to avoid undesirable saponification reactions. In this work, the electro-catalytic conversion of canola oil to biodiesel in a 1% aqueous methanolic and ethanolic reaction mixture was performed without the addition of external catalyst or cosolvent. An inexpensive stainless steel (SS electrode and a hybrid SS electrode coated with an ion-exchange resin catalyst were used as cathode materials while the anode was composed of a plain carbon paper. The cell voltages were varied from 10 to 40 V and the reaction temperature maintained at 20 or 40°C. The canola oil conversion rates were found to be superior at 40°C without saponification reactions for cell voltages below 30 V. The conversion rates were as high as 87% for the hybrid electrode and 81% for the plain SS electrode. This work could inspire new process development for the conversion of high water content feedstock for the production of second-generation biodiesel.

Study on the water flooding in the cathode of direct methanol fuel cells.

Science.gov (United States)

Im, Hun Suk; Kim, Sang-Kyung; Lim, Seongyop; Peck, Dong-Hyun; Jung, Doohwan; Hong, Won Hi

2011-07-01

Water flooding phenomena in the cathode of direct methanol fuel cells were analyzed by using electrochemical impedance spectroscopy. Two kinds of commercial gas diffusion layers with different PTFE contents of 5 wt% (GDL A5) and 20 wt% (GDL B20) were used to investigate the water flooding under various operating conditions. Water flooding was divided into two types: catalyst flooding and backing flooding. The cathode impedance spectra of each gas diffusion layer was obtained and compared under the same conditions. The diameter of the capacitive semicircle became larger with increasing current density for both, and this increase was greater for GDL B20 than GDL A5. Catalyst flooding is dominant and backing flooding is negligible when the air flow rate is high and current density is low. An equivalent model was suggested and fitted to the experimental data. Parameters for catalyst flooding and backing flooding were individually obtained. The capacitance of the catalyst layer decreases as the air flow rate decreases when the catalyst flooding is dominant.

Three-dimensional graphene as gas diffusion layer for micro direct methanol fuel cell

Science.gov (United States)

Zhu, Yingli; Zhang, Xiaojian; Li, Jianyu; Qi, Gary

2018-05-01

The gas diffusion layer (GDL), as an important structure of the membrane electrode assembly (MEA) of the direct methanol fuel cell (DMFC), provides a support layer for the catalyst and the fuel and the product channel. Traditionally, the material of GDL is generally carbon paper (CP). In this paper, a new material, namely three-dimensional graphene (3DG) is used as GDL for micro DMFC. The experimental results reveal that the performance of the DMFC has been improved significantly by application of 3DG. The peak powers increase from 25 mW to 31.2 mW and 32 mW by using 3DG as the anode and cathode GDL instead of CP, respectively. The reason may be the decrease of charge and mass transfer resistance of the cell. This means that the unique 3D porous architecture of the 3DG can provide lower contact resistance and sufficient fuel diffusion paths. The output performance of the cell will be further improved when porous metal current collectors is used.

Methanol from biomass and hydrogen

International Nuclear Information System (INIS)

Anon.

1989-01-01

For Hawaii in the near term, the only liquid fuels indigenous sources will be those that can be made from biomass, and of these, methanol is the most promising. In addition, hydrogen produced by electrolysis can be used to markedly increase the yield of biomass methanol. This paper calculates cost of producing methanol by an integrated system including a geothermal electricity facility plus a plant producing methanol by gasifying biomass and adding hydrogen produced by electrolysis. Other studies cover methanol from biomass without added hydrogen and methanol from biomass by steam and carbon dioxide reforming. Methanol is made in a two-step process: the first is the gasification of biomass by partial oxidation with pure oxygen to produce carbon oxides and hydrogen, and the second is the reaction of gases to form methanol. Geothermal steam is used to generate the electricity used for the electrolysis to produce the added hydrogen

A direct hybrid S{sub N} method for slab-geometry lattice calculations

Energy Technology Data Exchange (ETDEWEB)

Silva, Davi J.M.; Barros, Ricardo C., E-mail: rcbarros@pq.cnpq.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Programa de Pos-graduacao em Modelagem Computacional; Zani, Jose H. [Fundacao Educacional Serra dos Orgaos, Teresopolis, RJ (Brazil). Ciencia da Computacao

2011-07-01

In this work we describe a hybrid direct method for calculating the thermal disadvantage factor and the neutron flux distribution in fuel-moderator lattices. For the mathematical model, we use the one-speed slab-geometry discrete ordinates (S{sub N}) transport equation with linearly anisotropic scattering. The basic idea is to use higher order angular quadrature set in the highly absorbing fuel region (S{sub NF}) and lower order angular quadrature set in the diffusive moderator region (S{sub NM}) , i.e., N{sub F} > N{sub M}. We apply special continuity conditions based on the equivalence of the S{sub N} and P{sub N-1} equations, which characterize the hybrid model. Numerical results to a typical model problem are given to illustrate the accuracy and the efficiency of the offered hybrid method. (author)

Pt-Ru/CeO2/carbon nanotube nanocomposites: an efficient electrocatalyst for direct methanol fuel cells.

Science.gov (United States)

Sun, Zhenyu; Wang, Xiang; Liu, Zhimin; Zhang, Hongye; Yu, Ping; Mao, Lanqun

2010-07-20

Pt-Ru/CeO(2)/multiwalled carbon nanotube (MWNT) electrocatalysts were prepared using a rapid sonication-facilitated deposition method and were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and voltammetry. Morphological characterization by TEM revealed that CeO(2) nanoparticles (NPs) were in intimate contact with Pt-Ru NPs, and both were highly dispersed on the exteriors of nanotubes with a small size and a very narrow size distribution. Compared with the Pt-Ru/MWNT and Pt/MWNT electrocatalysts, the as-prepared Pt-Ru/CeO(2)/MWNT exhibited a significantly improved electrochemically active surface area (ECSA) and a remarkably enhanced activity toward methanol oxidation. The effects of the Pt-Ru loading and the Pt-to-Ru molar ratio on the electrocatalytic activity of Pt-Ru/CeO(2)/MWNT for methanol oxidation were investigated. We found that a maximum activity toward methanol oxidation reached at the 10 wt % of Pt-Ru loading and 1:1 of Pt-to-Ru ratio. Moreover, the role of CeO(2) in the catalysts for the enhancement of methanol oxidation was discussed in terms of both bifunctional mechanism and electronic effects.

A study on the dissymmetrical microporous layer structure of a direct methanol fuel cell

International Nuclear Information System (INIS)

Wang Tongtao; Lin Caishun; Fang Yong; Ye Feng; Miao Ruiying; Wang Xindong

2008-01-01

The effect of carbon type, carbon loading and microporous layer structure in the microporous layer on the performance of a direct methanol fuel cell (DMFC) at low temperature was investigated using electrochemical polarization techniques, electrochemical impedance spectroscopy, scanning electron microscope and other methods. Vulcan XC-72 carbon was found to be most suitable as a microporous layer for low temperature DMFC. Maximum fuel cell performance was obtained utilizing a microporous layer with carbon loading of 1.0 mg cm -2 when air was used as an oxidant. A membrane electrode assembly with 1.0 mg cm -2 Vulcan XC-72 carbon with 20 wt.% Teflon in the cathode and no microporous layer in the anode showed a maximum power density of 36.7 mW cm -2 at 35 deg. C under atmospheric pressure. The AC impedance study proved that a cell with a dissymmetrical microporous layer structure had lower internal resistance and mass transfer resistance, thus obtaining better performance

Methanol, Ethanol and Propanol in EHD liquid bridging

International Nuclear Information System (INIS)

Fuchs, Elmar C; Wexler, Adam D; Agostinho, Luewton L F; Ramek, Michael; Woisetschläger, Jakob

2011-01-01

When a high-voltage direct-current is applied to two beakers filled with water or polar liquid dielectrica, a horizontal bridge forms between the two beakers. In this work such bridges made of methanol, ethanol, 1-propanol and 2-propanol are investigated with polarimetry and thermography. Whereas methanol, ethanol and 1-propanol bridges become warm like a water bridge, a 2-propanol bridge cools down relative to the surroundings. It is shown how the different stability of the primary and secondary alcoholate ions and the resulting small difference in conductivity between 1-propanol and 2-propanol is responsible for this novel effect.

A validated near-infrared spectroscopic method for methanol detection in biodiesel

Science.gov (United States)

Paul, Andrea; Bräuer, Bastian; Nieuwenkamp, Gerard; Ent, Hugo; Bremser, Wolfram

2016-06-01

Biodiesel quality control is a relevant issue as biodiesel properties influence diesel engine performance and integrity. Within the European metrology research program (EMRP) ENG09 project ‘Metrology for Biofuels’, an on-line/at-site suitable near-infrared spectroscopy (NIRS) method has been developed in parallel with an improved EN14110 headspace gas chromatography (GC) analysis method for methanol in biodiesel. Both methods have been optimized for a methanol content of 0.2 mass% as this represents the maximum limit of methanol content in FAME according to EN 14214:2009. The NIRS method is based on a mobile NIR spectrometer equipped with a fiber-optic coupled probe. Due to the high volatility of methanol, a tailored air-tight adaptor was constructed to prevent methanol evaporation during measurement. The methanol content of biodiesel was determined from evaluation of NIRS spectra by partial least squares regression (PLS). Both GC analysis and NIRS exhibited a significant dependence on biodiesel feedstock. The NIRS method is applicable to a content range of 0.1% (m/m) to 0.4% (m/m) of methanol with uncertainties at around 6% relative for the different feedstocks. A direct comparison of headspace GC and NIRS for samples of FAMEs yielded that the results of both methods are fully compatible within their stated uncertainties.

A validated near-infrared spectroscopic method for methanol detection in biodiesel

International Nuclear Information System (INIS)

Paul, Andrea; Bräuer, Bastian; Bremser, Wolfram; Nieuwenkamp, Gerard; Ent, Hugo

2016-01-01

Biodiesel quality control is a relevant issue as biodiesel properties influence diesel engine performance and integrity. Within the European metrology research program (EMRP) ENG09 project ‘Metrology for Biofuels’, an on-line/at-site suitable near-infrared spectroscopy (NIRS) method has been developed in parallel with an improved EN14110 headspace gas chromatography (GC) analysis method for methanol in biodiesel. Both methods have been optimized for a methanol content of 0.2 mass% as this represents the maximum limit of methanol content in FAME according to EN 14214:2009. The NIRS method is based on a mobile NIR spectrometer equipped with a fiber-optic coupled probe. Due to the high volatility of methanol, a tailored air-tight adaptor was constructed to prevent methanol evaporation during measurement. The methanol content of biodiesel was determined from evaluation of NIRS spectra by partial least squares regression (PLS). Both GC analysis and NIRS exhibited a significant dependence on biodiesel feedstock. The NIRS method is applicable to a content range of 0.1% (m/m) to 0.4% (m/m) of methanol with uncertainties at around 6% relative for the different feedstocks. A direct comparison of headspace GC and NIRS for samples of FAMEs yielded that the results of both methods are fully compatible within their stated uncertainties. (paper)

Characterization of direct methanol fuel cell (DMFC) applications with H{sub 2}SO{sub 4} modified chitosan membrane

Energy Technology Data Exchange (ETDEWEB)

Osifo, Peter O.; Masala, Aluwani [Department of Chemical Engineering, Vaal University of Technology, Andries Potgieter Bolevald, P/Bag X021, Vanderbijlpark 1900, Gauteng (South Africa)

2010-08-01

Chitosan (Chs) flakes were prepared from chitin materials that were extracted from the exoskeleton of Cape rock lobsters in South Africa. The Chs flakes were prepared into membranes and the Chs membranes were modified by cross-linking with H{sub 2}SO{sub 4}. The cross-linked Chs membranes were characterized for the application in direct methanol fuel cells. The Chs membrane characteristics such as water uptake, thermal stability, proton resistance and methanol permeability were compared to that of high performance conventional Nafion 117 membranes. Under the temperature range studied 20-60 C, the membrane water uptake for Chs was found to be higher than that of Nafion. Thermal analysis revealed that Chs membranes could withstand temperature as high as 230 C whereas Nafion 117 membranes were stable to 320 C under nitrogen. Nafion 117 membranes were found to exhibit high proton resistance of 284 s cm{sup -1} than Chs membranes of 204 s cm{sup -1}. The proton fluxes across the membranes were 2.73 mol cm{sup -2} s{sup -1} for Chs- and 1.12 mol cm{sup -2} s{sup -1} Nafion membranes. Methanol (MeOH) permeability through Chs membrane was less, 1.4 x 10{sup -6} cm{sup 2} s{sup -1} for Chs membranes and 3.9 x 10{sup -6} cm{sup 2} s{sup -1} for Nafion 117 membranes at 20 C. Chs and Nafion membranes were fabricated into membrane electrode assemblies (MAE) and their performances measure in a free-breathing commercial single cell DMFC. The Nafion membranes showed a better performance as the power density determined for Nafion membranes of 0.0075 W cm{sup -2} was 2.7 times higher than in the case of Chs MEA. (author)

Developments for improved direct methanol fuel cell stacks for portable power

Energy Technology Data Exchange (ETDEWEB)

Cremers, C.; Stimming, U. [Bavarian Center for Applied Energy Research, ZAE Bayern, Abteilung 1, Walther-Meissner-Str. 6, D-85748 Garching (Germany); Technische Universitaet Muenchen, Department of Physics E19, James-Franck-Str. 1, D-85748 Garching (Germany); Scholz, M.; Seliger, W. [Bavarian Center for Applied Energy Research, ZAE Bayern, Abteilung 1, Walther-Meissner-Str. 6, D-85748 Garching (Germany); Racz, A. [Technische Universitaet Muenchen, Department of Physics E19, James-Franck-Str. 1, D-85748 Garching (Germany); Knechtel, W.; Rittmayr, J.; Grafwallner, F.; Peller, H. [ET EnergieTechnologie GmbH, Eugen-Saenger-Ring 4, D-85649 Brunnthal-Nord (Germany)

2007-02-15

Different aspects of the improvement of direct methanol fuel cell (DMFC) systems for portable power generation are investigated, in a project funded by the Bavarian state. The materials research focuses on the development of improved catalysts, in particular for the oxygen reduction reaction. Some recent results on supported ruthenium selenium catalysts are reported. In parallel, tests on other fuel cell materials are performed using MEAs made from industrial unsupported catalysts as the reference. These standard MEAs have catalyst loadings of about 11 mg cm{sup -2} and, at high air flux, can deliver current densities of about 500 mA cm{sup -2} and 100 mA cm{sup -2} at 110 C and 50 C, respectively. At low air flux and 50 C, current densities between 60 and 80 mA cm{sup -2} are possible rate at 500 mV. Using these MEAs, different commercial gas diffusion materials are tested as the cathode backing. Thus, it is found that the Sigracet materials by SGL Carbon are the most suitable for operation at a low air flux. Finally, a demonstration stack, comprised of up to ten cells, is developed using graphite PVDF compound bipolar plates by SGL Carbon. As will be reported, this stack shows a high homogeneity of cell voltages and stable operation under relevant conditions, using standard MEAs. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Methanol production by Mycobacterium smegmatis

International Nuclear Information System (INIS)

Weisman, L.S.; Ballou, C.E.

1988-01-01

Mycobacterium smegmatis cells produce [ 3 H]methanol when incubated with [methyl- 3 H]methionine. The methanol is derived from S-adenosylmethionine rather than methyltetrahydrofolate. M. smegmatis cells carboxymethylate several proteins, and some of the methanol probably results from their demethylation, but most of the methanol may come from an unidentified component with a high gel mobility. Although methanol in the medium reached 19 μM, it was not incorporated into the methylated mannose polysaccharide, a lipid carrier in this organism

Electro-oxidation of methanol diffused through proton exchange membrane on Pt surface: crossover rate of methanol

International Nuclear Information System (INIS)

Jung, Inhwa; Kim, Doyeon; Yun, Yongsik; Chung, Suengyoung; Lee, Jaeyoung; Tak, Yongsug

2004-01-01

Methanol crossover rate through proton exchange membrane (Nafion 117) was investigated with a newly designed electrochemical stripping cell. Nanosize Pt electrode was prepared by the electroless deposition. Distinct electrocatalytic oxidation behaviors of methanol inside membrane were similar to the methanol oxidation in aqueous electrolyte, except adsorption/desorption of hydrogen. The amount of methanol diffused through membrane was calculated from the charge of methanol oxidation during repetitive cyclic voltammetry (CV) and methanol crossover rate was estimated to be 0.69 nmol/s

METHANOL REMOVAL FROM METHANOL-WATER MIXTURE USING ACTIVATED SLUDGE, AIR STRIPPING AND ADSORPTION PROCESS: COMPARATIVE STUDY

Directory of Open Access Journals (Sweden)

SALAM K. AL-DAWERY

2015-12-01

Full Text Available An experimental research has been carried out in order to examine the removal of methanol from methanol-water mixtures using three different methods; activated sludge; activated carbon and air stripping. The results showed that the methanol was totally consumed by the bacteria as quickly as the feed entered the activated sludge vessel. Air stripping process has a limited ability for removing of methanol due to strong intermolecular forces between methanol and water; however, the results showed that the percentage of methanol removed using air pressure at 0.5 bar was higher than that of using air pressure of 0.25 bar. Removal of methanol from the mixture with a methanol content of 5% using activated carbon was not successful due to the limited capacity of the of the activated carbon. Thus, the activated sludge process can be considered as the most suitable process for the treatment of methanol-water mixtures.

Biological conversion of biogas to methanol using methanotrophs isolated from solid-state anaerobic digestate.

Science.gov (United States)

Sheets, Johnathon P; Ge, Xumeng; Li, Yueh-Fen; Yu, Zhongtang; Li, Yebo

2016-02-01

The aim of this work was to isolate methanotrophs (methane oxidizing bacteria) that can directly convert biogas produced at a commercial anaerobic digestion (AD) facility to methanol. A methanotrophic bacterium was isolated from solid-state anaerobic digestate. The isolate had characteristics comparable to obligate methanotrophs from the genus Methylocaldum. This newly isolated methanotroph grew on biogas or purified CH4 and successfully converted biogas from AD to methanol. Methanol production was achieved using several methanol dehydrogenase (MDH) inhibitors and formate as an electron donor. The isolate also produced methanol using phosphate with no electron donor or using formate with no MDH inhibitor. The maximum methanol concentration (0.43±0.00gL(-1)) and 48-h CH4 to methanol conversion (25.5±1.1%) were achieved using biogas as substrate and a growth medium containing 50mM phosphate and 80mM formate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fuel options for the fuel cell vehicle: hydrogen, methanol or gasoline?

International Nuclear Information System (INIS)

Thomas, C.E.; James, B.D.; Lomax, F.D. Jr.; Kuhn, I.F. Jr.

2000-01-01

Fuel cell vehicles can be powered directly by hydrogen or, with an onboard chemical processor, other liquid fuels such as gasoline or methanol. Most analysts agree that hydrogen is the preferred fuel in terms of reducing vehicle complexity, but one common perception is that the cost of a hydrogen infrastructure would be excessive. According to this conventional wisdom, the automobile industry must therefore develop complex onboard fuel processors to convert methanol, ethanol or gasoline to hydrogen. We show here, however, that the total fuel infrastructure cost to society including onboard fuel processors may be less for hydrogen than for either gasoline or methanol, the primary initial candidates currently under consideration for fuel cell vehicles. We also present the local air pollution and greenhouse gas advantages of hydrogen fuel cell vehicles compared to those powered by gasoline or methanol. (Author)

Electrokinetic transport of water and methanol in Nafion membranes as observed by NMR spectroscopy

International Nuclear Information System (INIS)

Hallberg, Fredrik; Vernersson, Thomas; Pettersson, Erik Thyboll; Dvinskikh, Sergey V.; Lindbergh, Goeran; Furo, Istvan

2010-01-01

Electrophoretic NMR (eNMR) and pulsed-field-gradient NMR (PFG-NMR) methods were used to study transport processes in situ and in a chemically resolved manner in the electrolyte of an experimental direct methanol fuel cell (DMFC) setup, constituted of several layers of Nafion 117. The measurements were conducted at room temperature for membranes fully swollen by methanol-water mixtures over a wide concentration interval. The experimental setup and the experimental protocol for the eNMR experiments are discussed in detail. The magnitude of the water and methanol self-diffusion coefficients show a good agreement with previously published data while the ratio of the two self-diffusion coefficients may indicate an imperfect mixing of the two solvent molecules. On the molecular level, the drag of water and methanol molecules by protons is roughly of the same magnitude, with the drag of methanol molecules increasing with increasing methanol content. The electro-osmotic drag defined on mass-flow basis increased for methanol from a low level with increasing methanol concentration while that of water remained roughly constant.

Combined local current distribution measurements and high resolution neutron radiography of operating direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Schroeder, Alexander; Wippermann, Klaus [Forschungszentrum Juelich GmbH (Germany). Inst. of Energy Research, IEF-3: Fuel Cells; Sanders, Tilman [RWTH Aachen (DE). Inst. for Power Electronics and Electrical Drives (ISEA); Arlt, Tobias [Helmholtz Centre Berlin (Germany). Inst. for Applied Materials

2010-07-01

Neutron radiography allows the investigation of the local fluid distribution in direct methanol fuel cells (DMFCs) under operating conditions. Spatial resolutions in the order of some tens of micrometers at the full test cell area are achieved. This offers the possibility to study practice-oriented, large stack cells with an active area of several hundred cm{sup 2} as well as specially designed, small test cells with an area of some cm{sup 2}. Combined studies of high resolution neutron radiography and segmented cell measurements are especially valuable, because they enable a correlation of local fluid distribution and local performance [1, 2]. The knowledge of this interdependency is essential to optimise the water management and performance respecting a homogeneous fluid, current and temperature distribution and to achieve high performance and durability of DMFCs. (orig.)

Vector Directional Distance Rational Hybrid Filters for Color Image Restoration

Directory of Open Access Journals (Sweden)

L. Khriji

2005-12-01

Full Text Available A new class of nonlinear filters, called vector-directional distance rational hybrid filters (VDDRHF for multispectral image processing, is introduced and applied to color image-filtering problems. These filters are based on rational functions (RF. The VDDRHF filter is a two-stage filter, which exploits the features of the vector directional distance filter (VDDF, the center weighted vector directional distance filter (CWVDDF and those of the rational operator. The filter output is a result of vector rational function (VRF operating on the output of three sub-functions. Two vector directional distance (VDDF filters and one center weighted vector directional distance filter (CWVDDF are proposed to be used in the first stage due to their desirable properties, such as, noise attenuation, chromaticity retention, and edges and details preservation. Experimental results show that the new VDDRHF outperforms a number of widely known nonlinear filters for multi-spectral image processing such as the vector median filter (VMF, the generalized vector directional filters (GVDF and distance directional filters (DDF with respect to all criteria used.

Imaging sequential dehydrogenation of methanol on Cu(110) with a scanning tunneling microscope.

Science.gov (United States)

Kitaguchi, Y; Shiotari, A; Okuyama, H; Hatta, S; Aruga, T

2011-05-07

Adsorption of methanol and its dehydrogenation on Cu(110) were studied by using a scanning tunneling microscope (STM). Upon adsorption at 12 K, methanol preferentially forms clusters on the surface. The STM could induce dehydrogenation of methanol sequentially to methoxy and formaldehyde. This enabled us to study the binding structures of these products in a single-molecule limit. Methoxy was imaged as a pair of protrusion and depression along the [001] direction. This feature is fully consistent with the previous result that it adsorbs on the short-bridge site with the C-O axis tilted along the [001] direction. The axis was induced to flip back and forth by vibrational excitations with the STM. Two configurations were observed for formaldehyde, whose structures were proposed based on their characteristic images and motions.

Sorption phenomena of methanol on heat treated coal; Netsushori wo hodokoshita sekitan no methanol kyuchaku tokusei

Energy Technology Data Exchange (ETDEWEB)

Yasuda, H.; Kaiho, M.; Yamada, O.; Soneda, Y.; Kobayashi, M.; Makino, M. [National Institute for Resources and Environment, Tsukuba (Japan)

1996-10-28

Experiments were carried out to learn methanol sorption characteristics of heat-treated coal. When Taiheiyo coal is heat-treated at 125{degree}C, performed with a first methanol adsorption at 25{degree}C, and then desorption at 25{degree}C, a site with strong interaction with methanol and a site with relatively weak interaction are generated in test samples. A small amount of methanol remains in both sites. Then, when the methanol is desorbed at as low temperature as 70{degree}C, the methanol in the site with strong interaction remains as it has existed therein, but the methanol in the site with relatively weak interaction desorbs partially, hence the adsorption amount in a second adsorption at 25{degree}C increases. However, when desorption is performed at as high temperature as 125{degree}C, the methanol in the site with strong interaction also desorbs, resulting in increased adsorption heat in the second adsorption. The adsorption velocity drops, however. Existence of methanol in a site with strong interaction affects the adsorption velocity, but no effect is given by methanol in a site with weak interaction. 3 refs., 4 figs.

Electrooxidation of methanol and ethylene glycol mixture on platinum and palladium in alkaline medium

Energy Technology Data Exchange (ETDEWEB)

Li, Z.Y.; Liang, Y.J.; Shan, X.D.; Lin, M.L.; Xu, C.W. [School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou (China); Jiang, S.P. [Department of Chemical Engineering, Faculty of Science and Engineering, Curtin University, Perth, WA (Australia)

2012-08-15

The performance of mixture of methanol and ethylene glycol (EG) oxidation has been studied on both Pt and Pd electrodes in alkaline medium. The activity of EG oxidation is better than that of methanol oxidation and the stability of EG oxidation is better than that of methanol and ethanol oxidation on the Pd electrode. The onset potential for ethanol oxidation is more negative 200 mV than that of EG, however the stability of EG oxidation on the Pd electrode is better than that of ethanol oxidation. The performance of methanol oxidation improves pronouncedly by adding a small amount of EG on both Pt and Pd electrodes. The onset potential and peak potential of mixture of methanol and EG oxidation are close to or more negative than that of sole methanol and EG oxidation on the Pd electrode. The mixture of methanol and EG is more easily to be electrochemically oxidized and gives a better performance than sole methanol and EG on the Pd electrode. The results show that the mixture of methanol and EG is a promising candidate as fuel in direct alcohol fuel cells. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Development of real-time measurement of methanol-concentration in polymer electrolyte membrane using a local NMR sensor

International Nuclear Information System (INIS)

Ogawa, Kuniyasu; Ito, Kohei; Haishi, Tomoyuki

2007-01-01

A real-time sensor to measure methanol concentration in polymer electrolyte membrane (PEM) was developed for reducing methanol cross-over in Direct Methanol Fuel Cell (DMFC). The principle of the methanol sensor is based on the chemical shift of CH and OH species under high magnetic field. The sensor consists of a planar surface coil of 1.3 mm outside diameter. NMR signal from PEM being exposed to CH3OH solvent was measured using NMR sensor. Time-dependence changes of methanol concentration in PEM were obtained from analyzing spectrum of NMR signal. (author)

Investigation of Novel Electrolytes for Use in Lithium-Ion Batteries and Direct Methanol Fuel Cells

Science.gov (United States)

Pilar, Kartik

Energy storage and conversion plays a critical role in the efficient use of available energy and is crucial for the utilization of renewable energy sources. To achieve maximum efficiency of renewable energy sources, improvements to energy storage materials must be developed. In this work, novel electrolytes for secondary batteries and fuel cells have been studied using nuclear magnetic resonance and high pressure x-ray scattering techniques to form a better understanding of dynamic and structural properties of these materials. Ionic liquids have been studied due to their potential as a safer alternative to organic solvent-based electrolytes in lithium-ion batteries and composite sulfonated polyetheretherketone (sPEEK) membranes have been investigated for their potential use as a proton exchange membrane electrolyte in direct methanol fuel cells. The characterization of these novel electrolytes is a step towards the development of the next generation of improved energy storage and energy conversion devices.

[Isolation of a methanol-utilizing strain and its application for determining methanol].

Science.gov (United States)

Guo, Jun; Gao, Wei; Zhang, Qiang; Qu, Fei; Lu, Dongtao; Zheng, Jun; Pang, Jinmei; Yang, Yujing

2013-08-04

To isolate and characterize bacteria that can be used todevelop microbial biosensor for methanol (MeOH) determination. We used selective medium and streak plate to isolate bacteria. Morphological, physiological characteristics and 16S rDNA sequence analysis were used to identify the strain. An MeOH biosensor was then developed by immobilizing M211 along with dissolved oxygen (O2) sensor. An MeOH utilizing bacterium was isolated from biogas-producing tank using methanol as the sole carbon source, and identified as Methylobacteriumorganophilium. Decrease of O2 concentration is linearly related to the MeOH concentration in the range from 0.02% to 1%, with the MeOH detection limit of 0.27 mg/L. The response time of the biosensor is within 20 min. Furthermore, the result of interference test and the detection of methanol sample are both satisfactory. Good results are obtained in interference test and the detection of methanol sample. The proposed method seems very attractive in monitoring methanol.

Self-directed learning readiness of Asian students: students perspective on a hybrid problem based learning curriculum.

Science.gov (United States)

Leatemia, Lukas D; Susilo, Astrid P; van Berkel, Henk

2016-12-03

To identify the student's readiness to perform self-directed learning and the underlying factors influencing it on the hybrid problem based learning curriculum. A combination of quantitative and qualitative studies was conducted in five medical schools in Indonesia. In the quantitative study, the Self Directed Learning Readiness Scale was distributed to all students in all batches, who had experience with the hybrid problem based curriculum. They were categorized into low- and high -level based on the score of the questionnaire. Three focus group discussions (low-, high-, and mixed level) were conducted in the qualitative study with six to twelve students chosen randomly from each group to find the factors influencing their self-directed learning readiness. Two researchers analysed the qualitative data as a measure of triangulation. The quantitative study showed only half of the students had a high-level of self-directed learning readiness, and a similar trend also occurred in each batch. The proportion of students with a high level of self-directed learning readiness was lower in the senior students compared to more junior students. The qualitative study showed that problem based learning processes, assessments, learning environment, students' life styles, students' perceptions of the topics, and mood, were factors influencing their self-directed learning. A hybrid problem based curriculum may not fully affect the students' self-directed learning. The curriculum system, teacher's experiences, student's background and cultural factors might contribute to the difficulties for the student's in conducting self-directed learning.

Dietary methanol and autism.

Science.gov (United States)

Walton, Ralph G; Monte, Woodrow C

2015-10-01

The authors sought to establish whether maternal dietary methanol during pregnancy was a factor in the etiology of autism spectrum disorders. A seven item questionnaire was given to women who had given birth to at least one child after 1984. The subjects were solicited from a large primary care practice and several internet sites and separated into two groups - mothers who had given birth to a child with autism and those who had not. Average weekly methanol consumption was calculated based on questionnaire responses. 550 questionnaires were completed by women who gave birth to a non-autistic child. On average these women consumed 66.71mg. of methanol weekly. 161 questionnaires were completed by women who had given birth to an autistic child. The average estimated weekly methanol consumption for this group was 142.31mg. Based on the results of the Wilcoxon rank sum-test, we see a significant difference between the reported methanol consumption rates of the two groups. This study suggests that women who have given birth to an autistic child are likely to have had higher intake of dietary sources of methanol than women who have not. Further investigation of a possible link of dietary methanol to autism is clearly warranted. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Hot new gamble on methanol

Energy Technology Data Exchange (ETDEWEB)

Hatton, J.

1981-10-01

Methanol from coal, wood, or natural gas is being considered as an extender or an alternative source of gasoline. Firms such as Nova and Celanese are gambling millions on the proposition that methanol is a crucial steppingstone to the fuels and chemicals of the future. With a new process developed by Mobil Oil, methanol from coal could be converted into gasoline. By the 1990s Imperial Oil Ltd. expects there will be at least one methanol plant using Alberta coal. These and other plans by the Alberta and British Columbia governments and by Canadian industry to produce methanol are reported.

The Asian methanol market

International Nuclear Information System (INIS)

Nagase, Hideki

1995-01-01

For the purpose of this presentation, Asia has been broadly defined as a total of 15 countries, namely Japan, Korea, Taiwan, China, Hong Kong, the Philippines, Thailand, Malaysia, Singapore, Indonesia, Myanmar, India, Vietnam, Australia and New Zealand. In 1994 and the first half of 1995, the methanol industry and its derivative industries experienced hard time, because of extraordinarily high methanol prices. In spite of this circumstance, methanol demand in Asian countries has been growing steadily and remarkably, following Asian high economic growth. Most of this growth in demand has been and will continue to be met by outside supply. However, even with increased import of methanol from outside of Asia, as a result of this growth, Asian trade volume will be much larger in the coming years. Asian countries must turn their collective attention to making logistics and transportation for methanol and its derivatives more efficient in the Asian region to make better use of existing supply resources. The author reviews current economic growth as his main topic, and explains the forecast of the growth of methanol demand and supply in Asian countries in the near future

Evaluation of reaction selectivity at various Pt/C electrocatalysts using a porous microelectrode in the presence of methanol and oxygen

International Nuclear Information System (INIS)

Shironita, Sayoko; Zhang, Weiqi; Sakai, Tsukasa; Umeda, Minoru

2014-01-01

Pt is most useful metal for various electrochemical reactions as an electrocatalyst. In a direct methanol fuel cell, Pt performs a catalytic activity for both the methanol oxidation reaction and oxygen reduction reaction; therefore, a Pt-based catalyst is used as an anode and a cathode. For the coexistence of methanol and oxygen due to methanol crossover through an electrolyte membrane during the cell operation, the direct methanol fuel cell performance decreases. However, if a higher selective reaction electrocatalyst can be developed, the cell performance will not be suppressed. In this study, the reaction selectivities of seven types of Pt supported on carbon (Pt/C) electrocatalysts were evaluated using a porous microelectrode in the presence of methanol and oxygen. As a result, some Pt/C catalysts showed a methanol oxidation selectivity, while the other catalysts showed an oxygen reduction selectivity. It was found that the percentage of edge-atom in the Pt particle is related to the methanol oxidation selectivity or the oxygen reduction selectivity. Moreover, each current density decreases with the increasing chemical shift in the Pt binding energy

Preparation of Carbon-Platinum-Ceria and Carbon-Platinum-Cerium catalysts and its application in Polymer Electrolyte Fuel Cell: Hydrogen, Methanol, and Ethanol

Science.gov (United States)

Guzman Blas, Rolando Pedro

This thesis is focused on fuel cells using hydrogen, methanol and ethanol as fuel. Also, in the method of preparation of catalytic material for the anode: Supercritical Fluid Deposition (SFD) and impregnation method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The first part of the thesis describes the general knowledge about Hydrogen Polymer Exchange Membrane Fuel Cell (HPEMFC),Direct Methanol Fuel Cell (DMFC) and Direct Ethanol Fuel Cell (DEFC), as well as the properties of Cerium and CeO2 (Ceria). The second part of the thesis describes the preparation of catalytic material by Supercritical Fluid Deposition (SFD). SFD was utilized to deposit Pt and ceria simultaneously onto gas diffusion layers. The Pt-ceria catalyst deposited by SFD exhibited higher methanol oxidation activity compared to the platinum catalyst alone. The linear sweep traces of the cathode made for the methanol cross over study indicate that Pt-Ceria/C as the anode catalyst, due to its better activity for methanol, improves the fuel utilization, minimizing the methanol permeation from anode to cathode compartment. The third and fourth parts of the thesis describe the preparation of material catalytic material Carbon-Platinum-Cerium by a simple and cheap impregnation method using EDTA as a chelating agent to form a complex with cerium (III). This preparation method allows the mass production of the material catalysts without additional significant cost. Fuel cell polarization and power curves experiments showed that the Carbon-Platinum-Cerium anode materials exhibited better catalytic activity than the only Vulcan-Pt catalysts for DMFC, DEFC and HPEMFC. In the case of Vulcan-20%Pt-5%w Cerium, this material exhibits better catalytic activity than the Vulcan-20%Pt in DMFC. In the case of Vulcan-40% Pt-doped Cerium, this material exhibits better catalytic activity than the Vulcan-40% Pt in DMFC, DEFC and HPEMFC. Finally, I propose a theory that explains the reason why the

A numerical study on RCCI engine fueled by biodiesel/methanol

International Nuclear Information System (INIS)

Zhou, D.Z.; Yang, W.M.; An, H.; Li, J.; Shu, C.

2015-01-01

Highlights: • Numerical study is done to investigate RCCI engine fueled by biodiesel/methanol. • A new biodiesel/methanol dual-fuel chemical reaction mechanism is developed. • Engine performance is improved with fuel reactivity stratification formed. • Soot and NO x significant reduce with methanol induction and fuel reactivity stratification. - Abstract: A 3-D numerical simulation platform based on the KIVA4-CHEMKIN code was constructed by incorporating a newly developed skeletal chemical kinetics mechanism to study the reactivity controlled compression ignition (RCCI) engine performance, combustion and emission characteristics. In the present study, methanol is assumed to be induced into the engine through the intake port, while biodiesel is directly injected into the engine by the end of the compression stroke. The skeletal biodiesel and methanol dual fuel chemical reaction mechanism coupled with CO, NO x and soot formation mechanisms was developed and validated by comparing the ignition delay predicted by the developed mechanism with that of the detailed biodiesel and methanol mechanisms, and also by comparing the simulation results of KIVA-CHEMKIN with the experimental results under different engine operating conditions. A good agreement has been achieved in terms of ignition delay, in-cylinder pressure and heat release rate (HRR). The methanol mass fraction was varied from 0% to 80% at an interval of 20% to form different reactivity stratification. Simulation results revealed that under 10% load conditions, the increasing methanol reduced the peak pressure and heat release rate, whereas under 50% and 100% loads, the peak pressure both appeared at 60% methanol induction. Also, the reactivity distribution and ringing intensity were discussed, aiming at investigating the fuel gradient effects and knocking level, respectively. For the emissions, a general decreasing trend on CO emission was observed at both 50% and 100% loads while at 10% load, a slight

Cytoplasmic-genetic male sterility gene provides direct evidence for some hybrid rice recently evolving into weedy rice

Science.gov (United States)

Zhang, Jingxu; Lu, Zuomei; Dai, Weimin; Song, Xiaoling; Peng, Yufa; Valverde, Bernal E.; Qiang, Sheng

2015-01-01

Weedy rice infests paddy fields worldwide at an alarmingly increasing rate. There is substantial evidence indicating that many weedy rice forms originated from or are closely related to cultivated rice. There is suspicion that the outbreak of weedy rice in China may be related to widely grown hybrid rice due to its heterosis and the diversity of its progeny, but this notion remains unsupported by direct evidence. We screened weedy rice accessions by both genetic and molecular marker tests for the cytoplasmic male sterility (CMS) genes (Wild abortive, WA, and Boro type, BT) most widely used in the production of indica and japonica three-line hybrid rice as a diagnostic trait of direct parenthood. Sixteen weedy rice accessions of the 358 tested (4.5%) contained the CMS-WA gene; none contained the CMS-BT gene. These 16 accessions represent weedy rices recently evolved from maternal hybrid rice derivatives, given the primarily maternal inheritance of this trait. Our results provide key direct evidence that hybrid rice can be involved in the evolution of some weedy rice accessions, but is not a primary factor in the recent outbreak of weedy rice in China. PMID:26012494

Cytoplasmic-genetic male sterility gene provides direct evidence for some hybrid rice recently evolving into weedy rice.

Science.gov (United States)

Zhang, Jingxu; Lu, Zuomei; Dai, Weimin; Song, Xiaoling; Peng, Yufa; Valverde, Bernal E; Qiang, Sheng

2015-05-27

Weedy rice infests paddy fields worldwide at an alarmingly increasing rate. There is substantial evidence indicating that many weedy rice forms originated from or are closely related to cultivated rice. There is suspicion that the outbreak of weedy rice in China may be related to widely grown hybrid rice due to its heterosis and the diversity of its progeny, but this notion remains unsupported by direct evidence. We screened weedy rice accessions by both genetic and molecular marker tests for the cytoplasmic male sterility (CMS) genes (Wild abortive, WA, and Boro type, BT) most widely used in the production of indica and japonica three-line hybrid rice as a diagnostic trait of direct parenthood. Sixteen weedy rice accessions of the 358 tested (4.5%) contained the CMS-WA gene; none contained the CMS-BT gene. These 16 accessions represent weedy rices recently evolved from maternal hybrid rice derivatives, given the primarily maternal inheritance of this trait. Our results provide key direct evidence that hybrid rice can be involved in the evolution of some weedy rice accessions, but is not a primary factor in the recent outbreak of weedy rice in China.

Controlled synthesis of Pt/CS/PW12-GNs composite as an anodic electrocatalyst for direct methanol fuel cells

International Nuclear Information System (INIS)

Li, Zhongshui; Lei, Fengling; Ye, Lingting; Zhang, Xiaofeng; Lin, Shen

2015-01-01

Controlled assembly in aqueous solution was used to synthesize the well-organized Pt/CS/PW 12 -GNs composite. By the aid of linear cationic polysaccharide chitosan, 2-D distribution worm-like Pt nanoparticles with their length and width of 15–20 and 3–4 nm, respectively, were formed on the surface of CS/PW 12 -GNs using HCOOH as a reducing agent at room temperature. The introduction of CS leads to well dispersion of worm-like Pt nanoparticles, the electroactivity of H 3 PW 12 O 40 (PW 12 ) alleviates CO poisoning toward Pt particles, and graphene nanosheets (GNs) ensure excellent electrical conductivity of the composites. The combined action among different components results in significantly enhanced catalytic activity of Pt/CS/PW 12 -GNs toward methanol oxidation and better tolerance of CO. The as-synthesized Pt/CS/PW 12 -GNs exhibit the forward peak current density of 445 mA mg −1 , which is much higher than that (220 mA mg −1 ) for Pt/C-JM (the commercially available Johnson Matthey Hispec4000 catalyst, simplified as Pt/C-JM) and some recently reported Pt/graphene-based nanomaterials. The construction of 2-D distribution worm-like Pt nanoparticles and facile wet chemical synthesis strategy provide a promising way to develop superior performance electrocatalysts for direct methanol fuel cells applications

Endogenous Methanol Regulates Mammalian Gene Activity

Science.gov (United States)

Komarova, Tatiana V.; Petrunia, Igor V.; Shindyapina, Anastasia V.; Silachev, Denis N.; Sheshukova, Ekaterina V.; Kiryanov, Gleb I.; Dorokhov, Yuri L.

2014-01-01

We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH) converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP) and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis. PMID:24587296

Endogenous methanol regulates mammalian gene activity.

Directory of Open Access Journals (Sweden)

Tatiana V Komarova

Full Text Available We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis.

Optimum concentration gradient of the electrocatalyst, Nafion® and poly(tetrafluoroethylene) in a membrane-electrode-assembly for enhanced performance of direct methanol fuel cells.

Science.gov (United States)

Liu, Jing Hua; Jeon, Min Ku; Lee, Ki Rak; Woo, Seong Ihl

2010-12-14

A combinatorial library of membrane-electrode-assemblies (MEAs) which consisted of 27 different compositions was fabricated to optimize the multilayer structure of direct methanol fuel cells. Each spot consisted of three layers of ink and a gradient was generated by employing different concentrations of the three components (Pt catalyst, Nafion® and polytetrafluoroethylene (PTFE)) of each layer. For quick evaluation of the library, a high-throughput optical screening technique was employed for methanol electro-oxidation reaction (MOR) activity. The screening results revealed that gradient layers could lead to higher MOR activity than uniform layers. It was found that the MOR activity was higher when the concentrations of Pt catalyst and Nafion ionomer decreased downward from the top layer to the bottom layer. On the other hand, higher MOR activity was observed when PTFE concentration increased downward from the top to the bottom layer.

Quaternized poly(vinyl alcohol)/alumina composite polymer membranes for alkaline direct methanol fuel cells

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Chien, Wen-Chen; Chiu, Sheng-Shin

The quaternized poly(vinyl alcohol)/alumina (designated as QPVA/Al 2O 3) nanocomposite polymer membrane was prepared by a solution casting method. The characteristic properties of the QPVA/Al 2O 3 nanocomposite polymer membranes were investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), micro-Raman spectroscopy, and AC impedance method. Alkaline direct methanol fuel cell (ADMFC) comprised of the QPVA/Al 2O 3 nanocomposite polymer membrane were assembled and examined. Experimental results indicate that the DMFC employing a cheap non-perfluorinated (QPVA/Al 2O 3) nanocomposite polymer membrane shows excellent electrochemical performances. The peak power densities of the DMFC with 4 M KOH + 1 M CH 3OH, 2 M CH 3OH, and 4 M CH 3OH solutions are 28.33, 32.40, and 36.15 mW cm -2, respectively, at room temperature and in ambient air. The QPVA/Al 2O 3 nanocomposite polymer membranes constitute a viable candidate for applications on alkaline DMFC.

Nanostructured Carbon Materials as Supports in the Preparation of Direct Methanol Fuel Cell Electrocatalysts

Directory of Open Access Journals (Sweden)

María Jesús Lázaro

2013-08-01

Full Text Available Different advanced nanostructured carbon materials, such as carbon nanocoils, carbon nanofibers, graphitized ordered mesoporous carbons and carbon xerogels, presenting interesting features such as high electrical conductivity and extensively developed porous structure were synthesized and used as supports in the preparation of electrocatalysts for direct methanol fuel cells (DMFCs. The main advantage of these supports is that their physical properties and surface chemistry can be tailored to adapt the carbonaceous material to the catalytic requirements. Moreover, all of them present a highly mesoporous structure, diminishing diffusion problems, and both graphitic character and surface area can be conveniently modified. In the present work, the influence of the particular features of each material on the catalytic activity and stability was analyzed. Results have been compared with those obtained for commercial catalysts supported on Vulcan XC-72R, Pt/C and PtRu/C (ETEK. Both a highly ordered graphitic and mesopore-enriched structure of these advanced nanostructured materials resulted in an improved electrochemical performance in comparison to the commercial catalysts assayed, both towards CO and alcohol oxidation.

Developments in the European methanol market

International Nuclear Information System (INIS)

Speed, J.

1995-01-01

In the late eighties/early nineties the World Methanol Market was basically divided into three regional markets--America, Asia Pacific and Europe. These markets were interrelated but each had its own specific characteristics and traditional suppliers. Now the situation has changed; in the mid nineties there is a Global Methanol Market with global players and effective global pricing and the European market is governed by events world-wide. Europe is however a specific market with specific characteristics which are different from those of other markets although it is also part of the Global Market. Hence before the author focuses on Europe he looks at the World Market. The paper discusses world methanol production and consumption by region, world methanol consumption by end use, world methanol supply demand balance, the west European market, western European methanol production, methanol imports to W. Europe, the Former Soviet Union supplies, W. European methanol consumption by end use, MTBE in Europe, duties on methanol imports into W. Europe, investment in Europe, the effect of the 1994/95 price spike, and key issues for the future of the industry

37 GHz METHANOL MASERS : HORSEMEN OF THE APOCALYPSE FOR THE CLASS II METHANOL MASER PHASE?

International Nuclear Information System (INIS)

Ellingsen, S. P.; Breen, S. L.; Sobolev, A. M.; Voronkov, M. A.; Caswell, J. L.; Lo, N.

2011-01-01

We report the results of a search for class II methanol masers at 37.7, 38.3, and 38.5 GHz toward a sample of 70 high-mass star formation regions. We primarily searched toward regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesized to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region.

Study on fuel supplying method and methanol concentration sensor for the high efficient operation of methanol fuel cells. Methanol nenryo denchi no unten ni okeru nenryo kyokyu hoho no kento to methanol nodo sensor no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Tsukui, Tsutomu; Doi, Ryota; Yasukawa, Saburo; Kuroda, Osamu [Hirachi, Ltd., Tokyo, (Japan)

1990-01-20

A fuel supplying method was studied and demonstrated, essential to the high efficient operation of methanol fuel cells. Methanol and water were supplied independently from each tank to an anordic electrolyte tank in a circulating system, detecting a methanol concentration and liquid level of anordic electrolyte by each sensor, respectively. A methanol sensor was also developed to detect accurately the concentration based on electrochemical reaction under a constant voltage. A detection control circuit was insulated from a constant-voltage power supply to prevent external noises. The methanol sensor output was compensated for temperature, and a new level sensing method was adopted to send out a command comparing different responses to electrolyte shortage. As the methanol fuel cell was operated with this fuel supplying system, the stable characteristics of the cell were obtained within the variation of {plus minus} 0.1mol/l from the specified methanol concentration. 6 refs., 17 figs., 1 tab.

Novel proton exchange membrane based on crosslinked poly(vinyl alcohol) for direct methanol fuel cells

Science.gov (United States)

Liu, Chien-Pan; Dai, Chi-An; Chao, Chi-Yang; Chang, Shoou-Jinn

2014-03-01

In this study, we report the synthesis and the characterization of poly (vinyl alcohol) based proton conducting membranes. In particular, we describe a novel physically and chemically PVA/HFA (poly (vinyl alcohol)/hexafluoroglutaric acid) blending membranes with BASANa (Benzenesulfonic acid sodium salt) and GA (Glutaraldehyde) as binary reaction agents. The key PEM parameters such as ion exchange capacity (IEC), water uptake, proton conductivity, and methanol permeability were controlled by adjusting the chemical composition of the membranes. The IEC value of the membrane is found to be an important parameter in affecting water uptake, conductivity as well as the permeability of the resulting membrane. Plots of the water uptake, conductivity, and methanol permeability vs. IEC of the membranes show a distinct change in the slope of their curves at roughly the same IEC value which suggests a transition of structural changes in the network. The proton conductivities and the methanol permeability of all the membranes are in the range of 10-3-10-2 S cm-1 and 10-8-10-7 cm2 s-1, respectively, depending on its binary crosslinking density, and it shows great selectivity compared with those of Nafion®-117. The membranes display good mechanical properties which suggest a good lifetime usage of the membranes applied in DMFCs.

Desenvolvimento de conjunto membrana-eletrodos para célula a combustível de metanol direto passiva Development of membrane electrode assembly for passive direct methanol fuel cell

Directory of Open Access Journals (Sweden)

Eli Carlos Lisboa Ferreira

2010-01-01

Full Text Available Direct methanol fuel cells (DMFCs without external pumps or other ancillary devices for fuel and oxidant supply are known as passive DMFCs and are potential candidates to replace lithium-ion batteries in powering portable electronic devices. This paper presents the results obtained from a membrane electrode assembly (MEA specifically designed for passive DMFCs. Appropriated electrocatalysts were prepared and the effect of their loadings was investigated. Two types of gas diffusion layers (GDL were also tested. The influence of the methanol concentration was analyzed in each case. The best MEA performance presented a maximum power density of 11.94 mW cm-2.

Hybrid Direct Carbon Fuel Cell Performance with Anode Current Collector Material

DEFF Research Database (Denmark)

Deleebeeck, Lisa; Kammer Hansen, Kent

2015-01-01

collectors were studied: Au, Ni, Ag, and Pt. It was shown that the performance of the direct carbon fuel cell (DCFC) is dependent on the current collector materials, Ni and Pt giving the best performance, due to their catalytic activity. Gold is suggested to be the best material as an inert current collector......The influence of the current collector on the performance of a hybrid direct carbon fuel cell (HDCFC), consisting of solid oxide fuel cell (SOFC) with a molten carbonate-carbon slurry in contact with the anode, has been investigated using current-voltage curves. Four different anode current...

Direct switching control of DC-DC power electronic converters using hybrid system theory

Energy Technology Data Exchange (ETDEWEB)

Zhao, J.; Lin, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wang, C. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wayne State Univ., Detroit, MI (United States). Div. of Engineering Technology

2010-07-01

A direct switching control (DSC) scheme for power electronics converters was described. The system was designed for use in both traditional and renewable energy applications as well as in electric drive vehicles. The proposed control scheme was based on a detailed hybrid system converter model that used model predictive control (MPC), piecewise affine (PWA) approximations and constrained optimal control methods. A DC-DC converter was modelled as a hybrid machine. Switching among different modes of the DC-DC converter were modelled as discrete events controlled by the hybrid controller. The modelling scheme was applied to a Buck converter. The DSC was used to control the switch of the power converter based on a hybrid machine model. Results of the study showed that the method can be used to regulate output voltage and inductor currents. The method also provides fast transient responses and effectively regulates both currents and voltage. The controller can be used to provide immediate responses to dynamic disturbances and output voltage fluctuations. 23 refs., 7 figs.

Generation of gaseous methanol reference standards

International Nuclear Information System (INIS)

Geib, R.C.

1991-01-01

Methanol has been proposed as an automotive fuel component. Reliable, accurate methanol standards are essential to support widespread monitoring programs. The monitoring programs may include quantification of methanol from tailpipe emissions, evaporative emissions, plus ambient air methanol measurements. This paper will present approaches and results in the author's investigation to develop high accuracy methanol standards. The variables upon which the authors will report results are as follows: (1) stability of methanol gas standards, the studies will focus on preparation requirements and stability results from 10 to 1,000 ppmv; (2) cylinder to instrument delivery system components and purge technique, these studies have dealt with materials in contact with the sample stream plus static versus flow injection; (3) optimization of gas chromatographic analytical system will be discussed; (4) gas chromatography and process analyzer results and utility for methanol analysis will be presented; (5) the accuracy of the methanol standards will be qualified using data from multiple studies including: (a) gravimetric preparation; (b) linearity studies; (c) independent standards sources such as low pressure containers and diffusion tubes. The accuracy will be provided as a propagation of error from multiple sources. The methanol target concentrations will be 10 to 500 ppmv

Three dimensional graphene foam supported platinum-ruthenium bimetallic nanocatalysts for direct methanol and direct ethanol fuel cell applications

Science.gov (United States)

Kung, Chih-Chien; Lin, Po-Yuan; Xue, Yuhua; Akolkar, Rohan; Dai, Liming; Yu, Xiong; Liu, Chung-Chiun

2014-06-01

A novel composite material of hierarchically structured platinum-ruthenium (PtRu) nanoparticles grown on large surface area three dimensional graphene foam (3D GF) is reported. 3D GF was incorporated with PtRu bimetallic nanoparticles as an electrochemical nanocatalyst for methanol and ethanol oxidation. PtRu/3D GF nanocatalyst showed a higher tolerance to poisoning by CO and exhibited improved catalytic activity for both methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). Cyclic voltammetry (CV) results and long-term cycling stability tests demonstrated that GF provided a promising platform for the development of electrochemical nanocatalysts. Specifically, PtRu/3D GF nanocatalyst showed excellent catalytic activity toward MOR and EOR compared with PtRu/Graphene (Commercial graphene), PtRu/C (Vulcan XC-72R carbon), and PtRu alone. The crystal size of PtRu on 3D GF was reduced to 3.5 nm and its active surface area was enhanced to 186.2 m2 g-1. Consequently, the MOR and EOR rates were nearly doubled on PtRu/3D GF compared to those on PtRu/Graphene.

Poly-dimethylsiloxane (PDMS) based micro-reactors for steam reforming of methanol

Energy Technology Data Exchange (ETDEWEB)

Ha, Ji Won; Kundu, Arunabha; Jang, Jae Hyuk

2010-11-15

A miniaturized methanol steam reformer with a serpentine type of micro-channels was developed based on poly-dimethylsiloxane (PDMS) material. This way of fabricating micro-hydrogen generator is very simple and inexpensive. The volume of a PDMS micro-reformer is less than 10 cm{sup 3}. The catalyst used was a commercial Cu/ZnO/Al{sub 2}O{sub 3} reforming catalyst from Johnson Matthey. The Cu/ZnO/Al{sub 2}O{sub 3} reforming catalyst particles of mean diameter 50-70 {mu}m was packed into the micro-channels by injecting water based suspension of catalyst particles at the inlet point. The miniaturized PDMS micro-reformer was operated successfully in the operating temperatures of 180-240 C and 15%-75% molar methanol conversion was achieved in this temperature range for WHSV of 2.1-4.2 h{sup -1}. It was not possible to operate the micro-reformer made by pure PDMS at temperature beyond 240 C. Hybrid type of micro-reformer was fabricated by mixing PDMS and silica powder which allowed the operating temperature around 300 C. The complete conversion (99.5%) of methanol was achieved at 280 C in this case. The maximum reformate gas flow rate was 30 ml/min which can produce 1 W power at 0.6 V assuming hydrogen utilization of 60%. (author)

Methanol electro-oxidation on Pt/C modified by polyaniline nanofibers for DMFC applications

Energy Technology Data Exchange (ETDEWEB)

Zhiani, Mohammad; Rezaei, Behzad; Jalili, Jalal [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran)

2010-09-15

In the present study, in order to achieve an inexpensive tolerable anode catalyst for direct methanol fuel cell applications, a composite of polyaniline nanofibers and Pt/C nano-particles, identified by PANI/Pt/C, was prepared by in-situ electropolymerization of aniline and trifluoromethane sulfonic acid on glassy carbon. The effect of synthesized PANI nanofibers in methanol electrooxidation reaction was compared by bare Pt/C by different electrochemical methods such as; cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry. Scanning electron microscopy (SEM) was also employed to morphological study of the modified catalyst layer. The test results reveal that introduction of PANI nanofibers within catalyst layer improves the catalyst activity in methanol oxidation, hinders and prevents catalyst from more poisoning by intermediate products of methanol oxidation and improves the mechanical properties of the catalyst layer. SEM images also indicate that PANI nanofibers placed between platinum particles and anchor platinum particles and alleviate the Pt migration during methanol electrooxidation. (author)

Nafion titania nanotubes nanocomposite electrolytes for high-temperature direct methanol fuel cells

CSIR Research Space (South Africa)

Cele, NP

2012-01-01

Full Text Available electrolytes membranes. This promotes to study the Nafion/TNTs nanocomposite membranes behaviour with the aim to improve Nafion properties such as fuel permeability and thermal and mechanical stability. Nafion, whose primary structure consists of acid... membrane properties, further investigations were carried out. In this study, the effects of TiO2 nanotubes on Nafion properties such as water uptake, thermal stability, methanol (MeOH) permeability, and ion conductivity were investigated...

Methanol from biomass: A technoeconomic analysis

International Nuclear Information System (INIS)

Stevens, D.J.

1991-01-01

Biomass-derived methanol offers significant potential as an alternative transportation fuel. Methanol is cleaner burning and has a lower flame temperature than gasoline. These characteristics can result in lower carbon monoxide and nitrogen oxide emissions when methanol is used as a fuel. Methanol produced from biomass offers potential advantages over that from other sources. When produced from biomass which is subsequently regrown, methanol does not contribute net emissions of carbon dioxide, a greenhouse gas, to the atmosphere. The introduction of alternative fuels will likely be driven by a number of political and economic decisions. The ability of biomass to compete with other resources will be determined in part by the economics of the production systems. In this paper, recent technoeconomic analyses of biomass-methanol systems are presented. The results are compared with methanol production from coal and natural gas

Catalytic methanol dissociation

International Nuclear Information System (INIS)

Alcinikov, Y.; Fainberg, V.; Garbar, A.; Gutman, M.; Hetsroni, G.; Shindler, Y.; Tatrtakovsky, L.; Zvirin, Y.

1998-01-01

Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

Autonomous electrochemical biosensors: A new vision to direct methanol fuel cells.

Science.gov (United States)

Sales, M Goreti F; Brandão, Lúcia

2017-12-15

A new approach to biosensing devices is demonstrated aiming an easier and simpler application in routine health care systems. Our methodology considered a new concept for the biosensor transducing event that allows to obtain, simultaneously, an equipment-free, user-friendly, cheap electrical biosensor. The use of the anode triple-phase boundary (TPB) layer of a passive direct methanol fuel cell (DMFC) as biosensor transducer is herein proposed. For that, the ionomer present in the anode catalytic layer of the DMFC is partially replaced by an ionomer with molecular recognition capability working as the biorecognition element of the biosensor. In this approach, fuel cell anode catalysts are modified with a molecularly imprinted polymer (plastic antibody) capable of protein recognition (ferritin is used as model protein), inserted in a suitable membrane electrode assembly (MEA) and tested, as initial proof-of-concept, in a non-passive fuel cell operation environment. The anchoring of the ionomer-based plastic antibody on the catalyst surface follows a simple one-step grafting from approach through radical polymerization. Such modification increases fuel cell performance due to the proton conductivity and macroporosity characteristics of the polymer on the TPB. Finally, the response and selectivity of the bioreceptor inside the fuel cell showed a clear and selective signal from the biosensor. Moreover, such pioneering transducing approach allowed amplification of the electrochemical response and increased biosensor sensitivity by 2 orders of magnitude when compared to a 3-electrodes configuration system. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Electrochemical characterization of nano-sized Pd-based catalysts as cathode materials in direct methanol fuel cells.

Science.gov (United States)

Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

2011-01-01

To improve the catalytic activity of palladium (Pd) as a cathode catalyst in direct methanol fuel cells (DMFCs), we prepared palladium-titanium oxide (Pd-TiO2) catalysts which the Pd and TiO2 nanoparticles were simultaneously impregnated on carbon. We selected Pd and TiO2 as catalytic materials because of their electrochemical stability in acid solution. The crystal structure and the loading amount of Pd and TiO2 on carbon were characterized by X-ray diffraction (XRD) and energy dispersive X-ray microanalysis (EDX). The electrochemical characterization of Pd-TiO2/C catalysts for the oxygen reduction reaction was carried out in half and single cell systems. The catalytic activities of the Pd-TiO2 catalysts were strongly influenced by the TiO2 content. In the single cell test, the Pd-TiO2 catalysts showed very comparable performance to the Pt catalyst.

Fabrication of MEA based on optimum amount of Co in PdxCo/C alloy nanoparticles as a new cathode for oxygen reduction reaction in passive direct methanol fuel cells

International Nuclear Information System (INIS)

Gharibi, Hussein; Golmohammadi, Farhad; Kheirmand, Mehdi

2013-01-01

Highlights: ► The optimal amount of Pd/Co in the catalyst layer reduces the polarization resistance in comparison with Pd alone. ► The Pd/Co in catalyst layer increases the Pd utilization in the ORR. ► The DMFC test results indicate that the MEA prepared from Pd 3 Co/C cathode exhibits best performance. -- Abstract: Carbon supported Pd and Pd x Co alloy electrocatalysts of different Pd x Co atomic ratios (x = 1, 2, 3 and 10) were prepared by the impregnation synthesis method at room temperature without heat treatment by ethylene glycol (EG) reduction. As prepared Pd x Co bimetallic nanoparticles show a single-phase face-centered-cubic (fcc) disordered structure. The performance of these electrodes in the ORR was measured with cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), inductive coupled plasma (ICP), X-ray diffraction (XRD); scanning electron microscopy coupled to energy dispersive X-ray (SEM–EDX) and transmission electron microscope (TEM). For synthesized Pd x Co/C electrocatalysts, the highest catalytic activity for the ORR, was found for a Pd:Co atomic ratio of 3:1 in acid media at the presence and absence of methanol with optimal Pd–Pd bond distance (0.2729 nm). Since the Pd x Co/C alloy electrocatalysts are inactive for the adsorption and oxidation of methanol, it can act as a methanol-tolerant ORR catalyst in a direct methanol fuel cell (DMFC). A membrane-electrode assembly (MEA) has been prepared by employing of the Pd 3 Co/C as a cathode for passive direct methanol fuel cell and characterized by polarization curves and impedance diagrams. The DMFC test results indicate that the MEA prepared from Pd 3 Co/C cathode exhibits better performance compared to the MEA prepared from Pt/C (Electrochem) and an in-house Pd/C catalyst synthesized, in terms of maximum power density and minimum charge transfer resistance

Discovery of a Ni-Ga catalyst for carbon dioxide reduction to methanol

DEFF Research Database (Denmark)

Studt, Felix; Sharafutdinov, Irek; Abild-Pedersen, Frank

2014-01-01

The use of methanol as a fuel and chemical feedstock could become very important in the development of a more sustainable society if methanol could be efficiently obtained from the direct reduction of CO 2 using solar-generated hydrogen. If hydrogen production is to be decentralized, small-scale CO...... 2 reduction devices are required that operate at low pressures. Here, we report the discovery of a Ni-Ga catalyst that reduces CO 2 to methanol at ambient pressure. The catalyst was identified through a descriptor-based analysis of the process and the use of computational methods to identify Ni......-Ga intermetallic compounds as stable candidates with good activity. We synthesized and tested a series of catalysts and found that Ni 5 Ga 3 is particularly active and selective. Comparison with conventional Cu/ZnO/Al 2 O 3 catalysts revealed the same or better methanol synthesis activity, as well as considerably...

Microwave-Assisted Synthesis of Co3(PO42 Nanospheres for Electrocatalytic Oxidation of Methanol in Alkaline Media

Directory of Open Access Journals (Sweden)

Prabhakarn Arunachalam

2017-04-01

Full Text Available Low-cost and high-performance advanced electrocatalysts for direct methanol fuel cells are of key significance for the improvement of environmentally-pleasant energy technologies. Herein, we report the facile synthesis of cobalt phosphate (Co3(PO42 nanospheres by a microwave-assisted process and utilized as an electrocatalyst for methanol oxidation. The phase formation, morphological surface structure, elemental composition, and textural properties of the synthesized (Co3(PO42 nanospheres have been examined by powder X-ray diffraction (XRD, Fourier transform-infrared spectroscopy (FT-IR, field emission-scanning electron microscopy (FE-SEM, high-resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, and nitrogen adsorption-desorption isotherm investigations. The performance of an electrocatalytic oxidation of methanol over a Co3(PO42 nanosphere-modified electrode was evaluated in an alkaline solution using cyclic voltammetry (CV and chronopotentiometry (CP techniques. Detailed studies were made for the methanol oxidation by varying the experimental parameters, such as catalyst loading, methanol concentration, and long-term stability for the electro-oxidation of methanol. The good electrocatalytic performances of Co3(PO42 should be related to its good surface morphological structure and high number of active surface sites. The present investigation illustrates the promising application of Co3(PO42 nanospheres as a low-cost and more abundant electrocatalyst for direct methanol fuel cells.

Power generation in fuel cells using liquid methanol and hydrogen peroxide

Science.gov (United States)

Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor); Chun, William (Inventor)

2002-01-01

The invention is directed to an encapsulated fuel cell including a methanol source that feeds liquid methanol (CH.sub.3 OH) to an anode. The anode is electrical communication with a load that provides electrical power. The fuel cell also includes a hydrogen peroxide source that feeds liquid hydrogen peroxide (H.sub.2 O.sub.2) to the cathode. The cathode is also in communication with the electrical load. The anode and cathode are in contact with and separated by a proton-conducting polymer electrolyte membrane.

Modifications for use of methanol or methanol-gasoline blends in automotive vehicles, September 1976-January 1980

Energy Technology Data Exchange (ETDEWEB)

Patterson, D.J.; Bolt, J.A.; Cole, D.E.

1980-01-01

Methanol or blends of methanol and gasoline as automotive fuels may be attractive means for extending the nation's petroleum reserves. The present study was aimed at identifying potential problems and solutions for this use of methanol. Retrofitting of existing vehicles as well as future vehicle design have been considered. The use of ethanol or higher alcohols was not addressed in this study but will be included at a later date. Several potentially serious problems have been identified with methanol use. The most attractive solutions depend upon an integrated combination of vehicle modifications and fuel design. No vehicle problems were found which could not be solved with relatively minor developments of existing technology providing the methanol or blend fuel was itself engineered to ameliorate the solution. Research needs have been identified in the areas of lubrication and materials. These, while apparently solvable, must precede use of methanol or methanol-gasoline blends as motor fuels. Because of the substantial costs and complexities of a retrofitting program, use of methanol must be evaluated in relation to other petroleum-saving alternatives. Future vehicles can be designed initially to operate satisfactorily on these alternate fuels. However a specific fuel composition must be specified around which the future engines and vehicles can be designed.

Thermodynamics of R-(+)-2-(4-Hydroxyphenoxy)propanoic Acid Dissolution in Methanol, Ethanol, and Methanol-Ethanol Mixture

Science.gov (United States)

Liu, Wei; Ma, Jinju; Yao, Xinding; Fang, Ruina; Cheng, Liang

2018-05-01

The solubilities of R-(+)-2-(4-hydroxyphenoxy)propanoic acid (D-HPPA) in methanol, ethanol and various methanol-ethanol mixtures are determined in the temperature range from 273.15 to 323.15 K at atmospheric pressure using a laser detecting system. The solubilities of D-HPPA increase with increasing mole fraction of ethanol in the methanol-ethanol mixtures. Experimental data were correlated with Buchowski-Ksiazczak λ h equation and modified Apelblat equation; the first one gives better approximation for the experimental results. The enthalpy, entropy and Gibbs free energy of D-HPPA dissolution in methanol, ethanol and methanol-ethanol mixtures were also calculated from the solubility data.

Valveless piezoelectric micropump for fuel delivery in direct methanol fuel cell (DMFC) devices

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tao; Wang, Qing-Ming [Department of Mechanical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, PA 15261 (United States)

2005-01-10

Fuel cells are being considered as an important technology that can be used for various power applications. For portable electronic devices such as laptops, digital cameras, cell phone, etc., the direct methanol fuel cell (DMFC) is a very promising candidate as a power source. Compared with conventional batteries, DMFC can provide a higher power density with a long-lasting life and recharging which is almost instant. However, many issues related to the design, fabrication and operation of miniaturized DMFC power systems still remain unsolved. Fuel delivery is one of the key issues that will determine the performance of the DMFC. To maintain a desired performance, an efficient fuel delivery system is required to provide an adequate amount of fuel for consumption and remove carbon dioxide generated from fuel cell devices at the same time. In this paper, a novel fuel delivery system combined with a miniaturized DMFC is presented. The core component of this system is a piezoelectric valveless micropump that can convert the reciprocating movement of a diaphragm activated by a piezoelectric actuator into a pumping effect. Nozzle/diffuser elements are used to direct the flow from inlet to outlet. As for DMFC devices, the micropump system needs to meet some specific requirements: low energy consumption but a sufficient fuel flow rate. Based on theoretical analysis, the effect of piezoelectric materials properties, driving voltage, driving frequency, nozzle/diffuser dimension, and other factors on the performance of the whole fuel cell system will be discussed. As a result, a viable design of a micropump system for fuel delivery can be achieved and some simulation results will be presented as well. (author)

Soil and groundwater remediation guidelines for methanol

International Nuclear Information System (INIS)

2010-12-01

Methanol is used by oil and gas operators to inhibit hydrate formation in the recovery of heavy oils, in natural gas production and transport, as well as in various other production applications. Emissions from methanol primary occur from miscellaneous solvent usage, methanol production, end-product manufacturing, and storage and handling losses. This document provided soil and groundwater remediation guidelines for methanol releases into the environment. The guidelines were consistent with the Alberta Environment tier 1 soil and groundwater framework. The chemical and physical properties of methanol were reviewed. The environmental fate and behavior of methanol releases was discussed, and the behaviour and effects of methanol in terrestrial and aquatic biota were evaluated. The toxicity of methanol and its effects in humans and mammalian species were reviewed. Soil quality and ground water quality guidelines were presented. Surface water and soil guideline calculation methods were provided, and ecological exposure and ground water pathways were discussed. Management limits for methanol concentrations were also provided. 162 refs., 18 tabs., 4 figs.

High performance anode based on a partially fluorinated sulfonated polyether for direct methanol fuel cells operating at 130 °C

Science.gov (United States)

Mack, Florian; Gogel, Viktor; Jörissen, Ludwig; Kerres, Jochen

2014-06-01

Due to the disadvantages of the Nafion polymer for the application in the direct methanol fuel cell (DMFC) especial at temperatures above 100 °C several polymers of the hydrocarbon type have already been investigated as membranes and ionomers in the DMFC. Among them were nonfluorinated and partially fluorinated arylene main-chain hydrocarbon polymers. In previous work, sulfonated polysulfone (sPSU) has been applied as the proton-conductive binder in the anode of a DMFC, ending up in good and stable performance. In continuation of this work, in the study presented here a polymer was prepared by polycondensation of decafluorobiphenyl and bisphenol AF. The formed polymer was sulfonated after polycondensation by oleum and the obtained partially fluorinated sulfonated polyether (SFS) was used as the binder and proton conductor in a DMFC anode operating at a temperature of 130 °C. The SFS based anode with 5% as ionomer showed comparable performance for the methanol oxidation to Nafion based anodes and significant reduced performance degradation versus Nafion and sPSU based anodes on the Nafion 115 membrane. Membrane electrode assemblies (MEAs) with the SFS based anode showed drastically improved performance compared to MEAs with Nafion based anodes during operation with lower air pressure at the cathode.

Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

NARCIS (Netherlands)

Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, M.; Ozcan, Mutlu

Objectives: This randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials. Methods: A total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in

Studies of catalyst material for the electro-oxidation of methanol, ethanol, formaldehyde and formic acid

International Nuclear Information System (INIS)

Bajwa, S.Z.; Ahmed, R.

2007-01-01

Fuel cell is an electrochemical device that converts the chemical energy of reaction directly into the electrical energy. It is highly efficient and environment friendly device. Normally used fuel in fuel cells is hydrogen, but due to the convenience in handling some other liquid fuels are also used and now direct methanol fuel cells are available in the market. Rapid electro-oxidation of the fuel at the fuel cell electrode is necessary for its optimum use. In addition to the methanol, other liquid fuels can also be used in the fuel cell. In this work, cyclic voltammetric studies have been done for the electro-oxidation of the methanol, ethanol, formic acid and formaldehyde on fuel cell catalyst. Platinum electrode is characterized by the measurement of active surface area and roughness factor. Classical electrochemical equations have been employed to find out rate constants for electro-oxidation of methanol fuel and calculations have been carried out to find out thermodynamic parameters. Exchange current density has been evaluated with reference to catalyst by drawing polarization curves. (author)

The Use of C-MnO2 as Hybrid Precursor Support for a Pt/C-MnxO1+x Catalyst with Enhanced Activity for the Methanol Oxidation Reaction (MOR

Directory of Open Access Journals (Sweden)

Alessandro H.A. Monteverde Videla

2015-07-01

Full Text Available Platinum (Pt nanoparticles are deposited on a hybrid support (C-MnO2 according to a polyol method. The home-made catalyst, resulted as Pt/C-MnxO1+x, is compared with two different commercial platinum based materials (Pt/C and PtRu/C. The synthesized catalyst is characterized by means of FESEM, XRD, ICP-MS, XPS and μRS analyses. MnO2 is synthesized and deposited over a commercial grade of carbon (Vulcan XC72 by facile reduction of potassium permanganate in acidic solution. Pt nanoparticles are synthesized on the hybrid support by a polyol thermal assisted method (microwave irradiation, followed by an annealing at 600 °C. The obtained catalyst displays a support constituted by a mixture of manganese oxides (Mn2O3 and Mn3O4 with a Pt loading of 19 wt. %. The electro-catalytic activity towards MOR is assessed by RDE in acid conditions (0.5 M H2SO4, evaluating the ability to oxidize methanol in 1 M concentration. The synthesized Pt/C-MnxO1+x catalyst shows good activity as well as good stability compared to the commercial Pt/C based catalyst.

Improvement on performance and efficiency of direct methanol fuel cells using hydrocarbon-based membrane electrode assembly

International Nuclear Information System (INIS)

Kim, Joon-Hee; Yang, Min-Jee; Park, Jun-Young

2014-01-01

Highlights: • Faradaic efficiency and water transfer coefficient (WTC) of DMFC MEAs are calculated based on mass balance measurements. • Faradaic efficiency of the HC-based MEAs is generally improved over the Nafion-based MEAs. • Nafion-based MEAs show a WTC of 3, whereas the HC-based MEAs show a very low WTC of -2. • Low WTC of the HC-based MEAs indicates the back-diffusion of water from the cathode to the anode. • Performance of HC-based MEAs is improved as the fuel stoichiometry increases, maintaining high Faradaic efficiency. - Abstract: In order to improve the energy efficiency (fuel efficiency and electrical power) of direct methanol fuel cells (DMFCs), the hydrocarbon (HC) membrane-based membrane electrode assemblies (MEAs) are investigated under various operating conditions. The MEAs are then compared with the conventional Nafion-based MEA in terms of their efficiency and performance. The Faradaic efficiency and water transfer coefficient (WTC) are calculated based on mass balance measurements. The Faradaic efficiency of the HC-based MEAs is improved over the Nafion-based MEAs since methanol crossover decreased. The performance of HC-based MEAs shows strong dependency on the anode stoichiometry at high current densities probably because of the limited mass transport of fuel, which is not observed for the Nafion-based MEAs. The Nafion-based MEAs show a WTC of 3, whereas the HC-based MEAs show a very low WTC of −2, indicating the back-diffusion of water from the cathode to the anode. This may have limited mass transport by interrupting proton conduction at high current densities. The performance of HC-based MEAs at high current densities is improved as the fuel stoichiometry increases; High Faradaic efficiency is maintained by decreasing the cathode stoichiometry

Purification, crystallization and preliminary X-ray crystallographic analysis of a methanol dehydrogenase from the marine bacterium Methylophaga aminisulfidivorans MPT

International Nuclear Information System (INIS)

Choi, Jin Myung; Kim, Hee Gon; Kim, Jeong-Sun; Youn, Hyung-Seop; Eom, Soo Hyun; Yu, Sung-Lim; Kim, Si Wouk; Lee, Sung Haeng

2011-01-01

In order to obtain molecular insights into the methanol-oxidizing system of M. aminisulfidivorans, a native heterotetrameric α 2 β 2 methanol dehydrogenase complex was directly purified from M. aminisulfidivorans MP T grown in the presence of methanol and crystallized. Methylophaga aminisulfidivorans MP T is a marine methylotrophic bacterium that utilizes C 1 compounds such as methanol as a carbon and energy source. The released electron from oxidation flows through a methanol-oxidizing system (MOX) consisting of a series of electron-transfer proteins encoded by the mox operon. One of the key enzymes in the pathway is methanol dehydrogenase (MDH), which contains the prosthetic group pyrroloquinoline quinone (PQQ) and converts methanol to formaldehyde in the periplasm by transferring two electrons from the oxidation of one methanol molecule to the electron acceptor cytochrome c L . In order to obtain molecular insights into the oxidation mechanism, a native heterotetrameric α 2 β 2 MDH complex was directly purified from M. aminisulfidivorans MP T grown in the presence of methanol and crystallized. The crystal diffracted to 1.7 Å resolution and belonged to the monoclinic space group P2 1 (unit-cell parameters a = 63.9, b = 109.5, c = 95.6 Å, β = 100.5°). The asymmetric unit of the crystal contained one heterotetrameric complex, with a calculated Matthews coefficient of 2.24 Å 3 Da −1 and a solvent content of 45.0%

Notes on HTR applications in methanol production

International Nuclear Information System (INIS)

Santoso, B.; Barnert, H.

1997-01-01

Notes on the study of HTR applications are presented. The study in particular should be directed toward the most feasible applications of HTR for process heat generation. A prospective study is the conversion of CO 2 gas from Natuna to methanol or formic acid. Further studies needs to be deepened under the auspices of IAEA and countries that have similar interest. (author). 3 refs, 3 figs

Fuel and power coproduction: The Liquid Phase Methanol (LPMEOH{trademark}) process demonstration at Kingsport

Energy Technology Data Exchange (ETDEWEB)

Drown, D.P.; Brown, W.R.; Heydorn, E.C.; Moore, R.B.; Schaub, E.S.; Brown, D.M.; Jones, W.C.; Kornosky, R.M.

1997-12-31

The Liquid Phase Methanol (LPMEOH{trademark}) process uses a slurry bubble column reactor to convert syngas (primarily a mixture of carbon monoxide and hydrogen) to methanol. Because of its superior heat management, the process is able to be designed to directly handle the carbon monoxide (CO)-rich syngas characteristic of the gasification of coal, petroleum coke, residual oil, wastes, or of other hydrocarbon feedstocks. When added to an integrated gasification combined cycle (IGCC) power plant, the LPMEOH{trademark} process converts a portion of the CO-rich syngas produced by the gasifier to methanol, and the remainder of the unconverted gas is used to fuel the gas turbine combined-cycle power plant. The LPMEOH{trademark} process has the flexibility to operate in a daily electricity demand load-following manner. Coproduction of power and methanol via IGCC and the LPMEOH{trademark} process provides opportunities for energy storage for electrical demand peak shaving, clean fuel for export, and/or chemical methanol sales.

Methanol induces low temperature resilient methanogens and improves methane generation from domestic wastewater at low to moderate temperatures.

Science.gov (United States)

Saha, Shaswati; Badhe, Neha; De Vrieze, Jo; Biswas, Rima; Nandy, Tapas

2015-01-01

Low temperature (methanol is a preferred substrate by methanogens in cold habitats. The study hypothesizes that methanol can induce the growth of low-temperature resilient, methanol utilizing, hydrogenotrophs in UASB reactor. The hypothesis was tested in field conditions to evaluate the impact of seasonal temperature variations on methane yield in the presence and absence of methanol. Results show that 0.04% (v/v) methanol increased methane up to 15 times and its effect was more pronounced at lower temperatures. The qPCR analysis showed the presence of Methanobacteriales along with Methanosetaceae in large numbers. This indicates methanol induced the growth of both the hydrogenotrophic and acetoclastic groups through direct and indirect routes, respectively. This study thus demonstrated that methanol can impart resistance in methanogenic biomass to low temperature and can improve performance of UASB reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.

A sensor-less methanol concentration control system based on feedback from the stack temperature

International Nuclear Information System (INIS)

An, Myung-Gi; Mehmood, Asad; Ha, Heung Yong

2014-01-01

Highlights: • A new sensor-less methanol control algorithm based on feedback from the stack temperature is developed. • Feasibility of the algorithm is tested using a DMFC system with a recirculating fuel loop. • The algorithm precisely controls the methanol concentration without the use of methanol sensors. • The sensor-less controller shortens the time that the DMFC system requires to go from start-up to steady-state. • This controller is effective in handling unexpected changes in the methanol concentration and stack temperature. - Abstract: A sensor-less methanol concentration control system based on feedback from the stack temperature (SLCCF) has been developed. The SLCCF algorithm is embedded into an in-house LabVIEW program that has been developed to control the methanol concentration in the feed of direct methanol fuel cells (DMFCs). This control method utilizes the close correlation between the stack temperature and the methanol concentration in the feed. Basically, the amounts of methanol to be supplied to the re-circulating feed stream are determined by estimating the methanol consumption rates under given operating conditions, which are then adjusted by a proportional–integral controller and supplied into the feed stream to maintain the stack temperature at a set value. The algorithm is designed to control the methanol concentration and the stack temperature for both start-up and normal operation processes. Feasibility tests with a 200 W-class DMFC system under various operating conditions confirm that the algorithm successfully maintains the methanol concentration in the feed as well as the stack temperature at set values, and the start-up time required for the DMFC system to reach steady-state operating conditions is reduced significantly compared with conventional sensor-less methods

Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

Science.gov (United States)

Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

A Review on the Fabrication of Electrospun Polymer Electrolyte Membrane for Direct Methanol Fuel Cell