The separation of hydrogen from refinery recycle streams is energy intensive in that it requires cooling and may require decompression of the streams prior to separation by either membranes or pressure swing adsorption. The recovered hydrogen must then be recompressed and reheated to process conditions. This project will develop a cost-effective, thin-film composite inorganic membrane to produce purified hydrogen at the temperature of the hydrotreater and with a small pressure driving force. As a consequence, a higher pressure permeate will be supplied, and a considerable amount of energy will be saved. Specific objectives include: (1) developing an ultra thin micro porous hydrogen separation membrane with a higher hydrogen permeation rate at a higher selectivity compared to existing materials, (2) demonstrating its utility in the separation of mixed hydrogen streams at elevated temperatures, and (3) scaling the membrane to commercially viable module sizes for testing in selected industrial sites. During Phase I several membrane materials will be synthesized, ground to submicron powders, and formed into a membrane with a thickness less than 20 microns. Then, a proprietary procedure will be used to apply this film to a micro porous support layer, fused to provide mechanical strength. The membranes will be characterized analytically; and their ability to separate hydrogen from nitrogen, at temperatures characteristic of refining operations (300 - 500ยบ C), will be determined.
Commercial Applications and Other Benefits as described by the awardee: It is estimated that U.S. refiners use more than 2 billion standard cubic feet per day of hydrogen in the removal of sulfur from gasoline and diesel fuel streams. Because hydrogen treat gas rates are higher than consumption rates, the reactor off-gas is left with substantial amounts of hydrogen, which must be purified before it is recycled. Thus, a major opportunity exists to commercialize the new membrane process in the refining industry (especially at a time when lower sulfur levels in transportation fuels are being mandated, requiring even more hydrogen to remove this sulfur.)
