甲醇制氢铜铝尖晶石缓释催化剂的研究—不同铜源合成的影响

Cu-Al spinel as a sustained release catalyst for H_2 production from methanol steam reforming: Effects of different copper sources

以拟薄水铝石为铝源,氢氧化铜、乙酸铜和硝酸铜等为铜源,采用固相法合成Cu-Al尖晶石催化剂。采用TG-MS、XRD、H2-TPR、BET和XANES等表征技术,对合成过程、产物的物相、还原性质及表层结构进行研究,并考察了甲醇重整制氢的缓释催化性能。结果表明,三种铜源都得到尖晶石固溶体,其晶粒粒径相差不大,但其比表面积(25.4-65.9 m2/g)、孔容(0.213-0.434 cm3/g)、表面结构(Cu的分布)以及还原性能有明显的差别,从而导致不同的缓释催化行为。在甲醇重整反应过程中,铜铝缓释催化剂通过反应条件下还原释放活性铜物种而起催化作用。以氢氧化铜合成的催化剂活性高,反应稳定性好,反应后生成的Cu粒子最小(6.6 nm),其表现出优异的催化性能。

Cu-Al spinel catalysts were synthesized by the solid-state reaction method using pseudo-boehmite as the Al source and hydroxides,acetates and nitrates of copper as the Cu source. Several techniques such as TGMS,XRD,H2-TPR,BET and XANES were employed for the exploration of the synthetic process,phase composition,reduction behaviors and surface structure of the catalysts. Moreover,the catalytic properties for methanol steam reforming（MSR） of these catalysts were evaluated. The obtained results showed that spinel solid solution can be successfully synthesized with the three different Cu sources. The synthesized spinels showed little difference in crystalline size,but their specific surface area（25. 4-65. 9 m2/g）,pore volume（0. 213-0.434 cm3/g）,surface structure（distribution of Cu） and reduction properties were quite different,which led to different catalytic behavior and performance. During the methanol steam reforming reaction,active Cu species can be released from Cu-Al spinel structure. The catalyst synthesized from copper（II） hydroxide shows excellent catalytic performance for MSR as it generates the smallest Cu particles（6.6 nm）.