Reforming methanol

A schematic diagram of a methanol-fueled PEFC system is shown in Fig. 27-65. A methanol reformer (to convert CH3OH to H9 and CO9... 

In contrast with the AFC, the PAFC can demonstrate reliable operation with 40 percent to 50 percent system efficiency even when operating on low quality fuels, such as waste residues. This fuel flexibility is enabled by higher temperature operation (200°C vs. 100°C for the AFC) since this raises electro-catalyst tolerance toward impurities. Flowever, the PAFC is still too heavy and lacks the rapid start-up that is nec-essaiy for vehicle applications because it needs preheating to 100°C before it can draw a current. This is unfortunate because the PAFC s operating temperature would allow it to thermally integrate better with a methanol reformer. 

The authors developed a multi-layered microreactor system with a methanol reforma- to supply hydrogen for a small proton exchange membrane fiiel cell (PEMFC) to be used as a power source for portable electronic devices [6]. The microreactor consists of four units (a methanol reformer with catalytic combustor, a carbon monoxide remover, and two vaporizers), and was designed using thermal simulations to establish the rppropriate temperature distribution for each reaction, as shown in Fig. 3. 

In this study, an integrated methanol reformer including an evaporator and a combustor was fabricated and tested. Previous tests of the reformer with a number of on-off cycles revealed that non-uniform temperature distribution caused hot spots within the combustion plate, resulting in cracking of the welded region of the reformer. Therefore, emphasis was made to achieve a uniform temperature distribution within the reformer. In addition, start-up characteristics of the complete reforming system were investigated. 

Performance of an integrated methanol reformer combined with a FROX reactor... 

A complete methanol reforming system was constructed by coimecting the integrated reformer with a PROX reactor. Fig. 5 shows the evolution of temperature at the gas outlet of the evaporator, reformer and PROX reactor during the start-up. Temperature of the reformer became stable in 5 min after introduction of the reactant. The reformer produced hydrogen up to 1.5L/min with methanol conversion higher than 95%, enough to run a lOOW PEMFC. 

Figure 2.21 Computational domain of a multichannel reactor for methanol reforming.

Also a simulation of the flow field in the methanol-reforming reactor of Figure 2.21 by means of the finite-volume method shows that recirculation zones are formed in the flow distribution chamber (see Figure 2.22). One of the goals of the work focused on the development of a micro reformer was to design the flow manifold in such a way that the volume flows in the different reaction channels are approximately the same [113]. In spite of the recirculation zones found, for the chosen design a flow variation of about 2% between different channels was predicted from the CFD simulations. In the application under study a washcoat cata-... 

Laniecki, M. Kazmierczak-Rosik, K., Steam-methanol reforming over zeolitic materials. In 12th World Hydrogen Energy Conference, Bolcich, J. C. Veziroglu, T. N. Eds., Buenos Aires, June 21-25,1998, pp. 661-668. 

Gadhe, J. B. Gupta, R. B., Hydrogen production by methanol reforming in supercritical water Suppression of methane formation. Industrial and Engineering Chemistry Research 2005, 44, 4577-4585. 

MRH (1) [Methanol reformer hydrogen] A process for generating hydrogen from methanol, separating it by PSA. Developed by the Marutani CPE Company. 

Within the literature, FTIR has been used to identify the various intermediate species formed over Au/Ti02 under both methanol decomposition and methanol reforming conditions.65 In the case of methanol decomposition, unlike methanol reforming, only methoxy species associated with Ti02 were observed. 

Fuel cell vehicles with onboard methanol reformers would have very low emissions of urban air pollutants. Daimler-Chrysler has built demonstration fuel cell vehicles that convert methanol to hydrogen. 

Onboard gasoline reforming could serve as an interim step and accelerate the commercialization of PEM fuel cells. It does not require a hydrogen infrastructure. Onboard methanol reformers are likely to be even less efficient than gasoline reformers. For the immediate future, increases in methanol production are likely to come from overseas natural gas. 

In Germany, Daimler-Benz s fuel cell prototypes included the NE-CAR III. This was a Mercedes-Benz A-Class car with Ballard s methanol-reformed fuel cell system. 

The FCX-V2 used a Honda designed fuel cell and reformer. Downsizing the methanol reformer remained to be done and both test cars had room only for a driver and passenger. Fuel cell components took up the rear seats. The need to test fuel cell cars under real-life conditions is one reason Honda joined DaimlerChrysler in the California Fuel Cell Partnership. More recently Honda announced the first lease of its advanced... 

Toyota began to work with PEM cells in 1989 and produced a methanol reformed car, the FCEV, in 1997. This car was based on Toyota s electric RAV4. 

Toyota has been sharing technology with partner GM on electric, hybrid, and fuel cell cars. In 1998, the research division was testing methanol reformers and metal hydride hydrogen storage and had prototypes of each. 

All fuel cells for use in vehicles are based on proton-exchange-membrane fuel cell (PEMFC) technology. The methanol fuel-processor fuel cell (FPFC) vehicle comprises an on-board fuel processor with downstream PEMFC. On-board methanol reforming was a development focus of industry for a number of years until around 2002. Direct-methanol fuel cells (DMFC) are no longer considered for the propulsion of commercial vehicles in the industry (see also Chapter 13). 

A detailed analysis published for fuel-cell drive systems by Schirrmeister et al. (2002) showed a specific cost breakdown of the added value of a fuel-cell drive system powered by methanol (a methanol reformer was a reasonable alternative at that time)... 

Researchers at Lehigh University are developing a methanol reforming silicon reactor with a palladium membrane for a hydrogen purification system built using semiconductor fabrication techniques. The device is designed to produce hydrogen for fuel cells for portable electronic devices, such as laptop computers and cell phones. 

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