Methanol Reformer Hydrogen

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

Reforming reaction takes place at high temperatures. Typically, in vehicle systems utilizing methanol reformation, hydrogen is directly injected into the cell where methanol and water are vaporized to form H2, CO, and C02 [6], This reformation takes place at approximately 280°C [6], Materials that operate at these temperatures are quite costly. In addition, separate loop cooling systems (currently in the form of humidifiers) are required to keep the overall cell temperature down and the water management under control for a PEM fuel cell. An aqueous membrane is required to prevent boiling, temperatures below 100°C are necessary [6],... 

Hydrogen Liquefaction. Hydrogen can be produced from caustic—chlorine electrolytic cells, by decomposition of ammonia or methanol, or by steam—methane reforming. Hydrogen recovered by these methods must be further purified prior to Hquefaction. This is generally achieved by utilizing pressure swing adsorption methods whereby impurities are adsorbed on a soHd adsorbent. 

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. 

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. 

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. 

Onboard reforming for fuel cells depends on catalytic reactions to convert conventional hydrocarbon fuels, such as gasoline or methanol, into hydrogen that fuel cells can then use to produce electricity to power vehicles. 

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. 

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. 

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. 

For these low-temperature fuel cells, the development of catalytic materials is essential to activate the electrochemical reactions involved. This concerns the electro-oxidation of the fuel (reformate hydrogen containing some traces of CO, which acts as a poisoning species for the anode catalyst methanol and ethanol, which have a relatively low reactivity at low temperatures) and the electroreduction of the oxidant (oxygen), which is still a source of high energy losses (up to 30-40%) due to the low reactivity of oxygen at the best platinum-based electrocatalysts. 

Most fuel cells are powered by hydrogen, which can be fed to the fuel cell system directly or can be generated within the fuel cell system by reforming hydrogen-rich fuels such as methanol, ethanol, and hydrocarbon fuels. Direct methanol fuel cells (DMFCs), however, are powered by pure methanol. 

Figure 2.16 Methanol conversion as a function of temperature hydrogen selectivity vs. methanol conversion for autothermal methanol reforming [39] (by courtesy of ACS).

Methanol has a number of advantages for powering fuel cell vehicles. As the 2001 study for the caFCP noted, these include methanol s immediate availability without new upstream infrastructure, high hydrogen-carrying capacity, and ability to be readily stored, delivered, and carried on-board without pressurization. 22 In short, our transportation system and its infrastructure favor liquid fuels. Fuel cell vehicles with onboard methanol reformers would have very low emissions of urban air pollutants. Daimler-Chrysler has introduced demonstration fuel cell vehicles that convert methanol to hydrogen on board. 

A more detailed picture of a PEMFC system, with hydrogen produced by methanol reforming, including the auxiliary and control equipments, is given in Figure 9.6. 

Liu ST, et al. Hydrogen production by oxidative methanol reforming on Pd/ZnO catalyst preparation and supporting materials. Catal Today. 2007 129(3-4) 287-92. 

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