Development of the dimethyl ether steam reforming catalysts that suite for generating the CO-free hydrogen

二甲醚（DME）具有毒性小、燃烧时不含氮氧化物或微粒、易于处理等优点，是潜在的下一代清洁燃料。研究了二甲醚流重整制无co氢的催化剂（SRDME），用于聚合物电解质燃料膜电池。采用溶胶-凝胶法制备的γ-Al_2O_3、SiO_2、Cu/Al_2O_3、Ru/Al_2O_3、Cu/SiO_2等催化剂，浸渍法制备的Cu- zn /Al_2O_3和CuO-ZnO作为工业催化剂。溶胶-凝胶法制备的Al_2O_3催化剂主要生成H_2，仅生成Al_2O_3的甲醇。另一方面，Cu/SiO_2和SiO_2在甲醇蒸汽重整中表现优异，没有产生H_2。这些结果表明，γ-Al_2O_3，特别是路易斯酸位点，对二甲醚水解成甲醇有很好的效果，所生成的甲醇在活性金属（如铜）上转化为H_2和CO_2进行甲醇蒸汽重整。溶胶-凝胶法制备SRDME催化剂是一种很好的方法，因为γ-Al_2O_3、Lewis酸位和铜等活性金属位能够很好地混合并分布在催化剂表面。Cu/Al_2O_3是SRMDE的优良催化剂之一，在Cu/Al_2O_3中分别加入Zn、Fe和Mn可以提高H_2的产率；然而，CO的产量并没有减少。CO是由生成的H_2和CO_2通过相反的水气变换反应生成的，因此认为CO在ppm数量级或更低数量级的还原是非常困难的。以Cu-Zn(29-1wt%)/Al_2O_3催化剂为例，在275℃的反应温度下，95%的二甲醚转化为含有0.8% CO的H_2和CO_2。在低温（250 ~ 300℃）条件下，SRDME催化剂性能优异。2001-2003年，我们在日本催化学会的会议上做了3次报告，在日本化学学会的会议上做了7次报告。我们非常感谢对这项研究的支持。少

Dimethyl ether (DME) is a potential clean fuel of the next generation, because of less toxicity, burning without Nox or particulates, and ease of handling. We have studied catalysts which will produce CO-free hydrogen with stream reforming of DME (SRDME) for the use of hydrogen in polymer electrolyte fuel membrane cells.Catalysts prepared by the sol-gel method, such as γ-Al_2O_3, SiO_2, Cu/Al_2O_3, Ru/Al_2O_3, Cu/SiO_2, so on, Cu-Zn/Al_2O_3 prepared by the impregnation method, and CuO-ZnO as a commercial catalyst were used.The Al_2O_3 catalysts prepared by the sol-gel method mainly produced H_2, and in the case only of Al_2O_3 methanol was formed. On the other hand, the Cu/SiO_2 which was excellent for methanol steam reforming and SiO_2 produced no H_2. These results suggest that γ-Al_2O_3, especially the Lewis acid sites, is excellent for hydrolyzing DME into methanol and the methanol produced is reformed to H_2 and CO_2 over active metal for methanol steam reforming, such as copper. … More It is also found that the sol-gel method is excellent for preparing the suitable catalysts for SRDME, because γ-Al_2O_3, the Lewis acid sites, and active metal sites such as copper will be mixed and distributed well on the surfaces of the catalysts. Each addition of Zn, Fe, and Mn into Cu/Al_2O_3 that is one of the excellent catalysts for SRMDE improves the rate of H_2 production ; however, the CO production is not reduced. CO is formed with the opposite water gas shift reaction by generated H_2 and CO_2, therefore it was thought that the CO reduction in the ppm order or less orders is very difficult. However, for example, Cu-Zn(29-1wt%)/Al_2O_3 catalyst converts 95% of DME into H_2 and CO_2 containing 0.8% of CO at the reaction temperature, 275℃. The excellent catalysts for SRDME at low temperature (250-300℃) have been developed.(We had 3 presentations in the conferences of Catalysis Society of Japan, and 7 presentations in the conferences of The Chemical Society of Japan for 2001-2003. We are grateful for support of this research.) Less