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Click on “Download PDF” for the PDF version or on the title for the HTML version. If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options. Hydrogen Separation from Synthesis GasPublished by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org Citation: Paper number 056199, 2005 ASAE Annual Meeting . (doi: 10.13031/2013.19649) @2005Authors: Sushil Adhikari, Sandun Fernando Keywords: Hydrogen, Membranes, Permeance, Selectivity About 80% of the present world energy demand comes from fossil fuels. Unlike fossil fuels, using hydrogen as an energy source produce water as the only byproduct. Furthermore, use of hydrogen as an energy source could help to address issues related to energy security including global climate change and local air pollution. Moreover, hydrogen is abundantly available in the universe and possesses the highest energy content per unit of weight (i.e, 120.7 kJ/g) compared to any of the known fuels. Consequently, demand for hydrogen energy and production have been growing in the recent years. Most industrial processes for hydrogen production use steam reforming of methane. Thus, hydrogen produced in this way cannot be considered as a clean gas and new ways of hydrogen production have been studied all over the world in the last several years which could fulfill the goals of sustainability. Biomass gasification is one of the cleaner processes of producing hydrogen. However, the synthesis gas which could be produced by a biomass gasification process contains a number of gases other than hydrogen that should be cleaned up. Several purification methods have been studied for hydrogen purification depending up on the application types. Membrane separation process is an attractive alternative compared to mature technologies such as pressure swing adsorption and cryogenic distillation. This paper reports different types of membranes used for hydrogen separation from hydrogen rich mixtures. The study has found that much of the research has been focused on non-polymeric materials such as metal, molecular sieving carbon, zeolites and ceramics. High purity of hydrogen is available through dense metallic membranes and especially palladium and its alloys, which are very selective to hydrogen. Cost is the major barrier for the preparation of palladium membranes. Consequently, recent studies were focused on thin metallic membranes. Thin membranes would not only reduce the cost of materials but also increases the hydrogen flux. Metal alloys or composite metal membranes have been used for hydrogen purification. However, they are sensitive to some gases such as carbon monoxide and hydrogen sulfide. Therefore, ceramic membranes, inert to poisonous gases are desirable. Inorganic microporous membranes (pore sizes less than 2 nm) offer many advantages over thin-film palladium membranes for separation of hydrogen from a mixed-gas stream. More importantly, in microporous membranes, the flux is directly proportional to the pressure, whereas in palladium membranes it is proportional to the square root of the pressure. This paper discusses the advantages and disadvantages of different hydrogen separation membranes. Also, the paper reports performance of selected membranes in terms of hydrogen selectivity and permeability. (Download PDF) (Export to EndNotes)
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