Chapter Seven Methanol Reforming Processes

Abstract

Abstract Hydrogen is seen by many as the energy carrier for the future, and development of the science and technology needed to produce, store and utilize hydrogen has emerged as an international research priority. Hydrogen has the highest energy density of any non-nuclear fuel and can be easily converted to electrical and thermal energy via highly efficient, non-polluting processes. Fossil fuels like natural gas and crude oil are obvious sources for the large quantities of hydrogen needed to initiate the transition to a “Hydrogen Economy.”. Hydrogen can be produced either off-board or on-board way. Most of the studies for on-board hydrogen production for fuel cells are based on two types of compounds. One is oxygen containing compounds – methanol and ethanol, etc. The other option is hydrocarbons such as natural gas, gasoline and diesel fuel. Among them, methanol is the most attractive fuel for on-board hydrogen production because of its high H/C ratio, low reforming temperature and good miscibility with water. In addition, methanol is sulfur-free, eliminating the concerns with catalyst or electrode poisoning by sulfur. The absence of carbon–carbon (C—C) bonds in methanol comparatively reduces the risk of coking. The different reforming process of methanol (steam reforming of methanol (SRM), partial oxidation of methanol (POM) and oxidative methanol reforming (OMR)) has been discussed and compared. Primarily owing to advances of the materials (e.g. catalysts) and reactors, the processing of hydrocarbons into H2-rich gas has become fairly efficient. The chapter focuses on the different catalysts of recent literature and reactors by different workers for hydrogen production from methanol reforming process and operation of fuel cells from the production of hydrogen in this process. The commercial catalyst for SRM is Cu/ZnO/Al2O3. The other types of catalyst like ZrO2 supported catalyst or addition of ZrO2 and CeO2 in Cu/ZnO/Al2O3, CuO/CeO2 and Pd/ZnO have also been discussed. The appropriate selection of reforming reactor is required for its suitability as on-board source of hydrogen in automobile industries as well as electronic equipment. The different approaches in this regard have been discussed. These are fixed bed reactor, monolithic reactor, wall-coated heat exchanger, micro-channel reactor and metallic foam reactor. Among them, micro-channel reactor seems to be most promising in portable electronics with respect to its fast response in transient behavior, higher heat (which will lead to better temperature control inside reactor) and mass transfer characteristics, less channeling of flow of reactant and less pressure drop. The further work on the stability of the coated catalyst with high catalytic performance is still required. The larger version of micro-channel reactor, i.e. wall-coated heat exchanger with channels can also be promising for automotive applications. Studies on the integrated operation of methanol reformer with the fuel cell is very essential to apply it in on-board application. It is evident from the existing literature that the methanol reformer has a desirable fast response to achieve the reaction temperature and is highly suitable for use with fuel cells to power automobiles. However, more efforts are still needed on the cold start and transient characteristics of the reformer if it is to be used as an on-board vehicle fuel processor.