CuO/CeO_2-Al_2O_3催化剂中CuO高温迁移和固相反应的研究

CuO Transport and Thermal Solid-Solid Interaction in CuO/CeO_2-Al_2O_3 Catalysts

采用原位XRD、激光Raman光谱和TPR技术研究了不同温度焙烧的CuO/CeO2-Al2O3催化剂中CuO物种的存在形式及其高温固相反应。结果表明,300℃焙烧催化剂CuO以晶相和非晶相形式存在于CeO2-Al2O3的表层。600℃焙烧催化剂,表层CuO部分迁移到CeO2内层,并与载体Al2O3反应生成CuAl2O4。800℃焙烧催化剂,除了极少量CuO以晶相和非晶相形式存在于CeO2-Al2O3的表层外,大部分CuO迁移到CeO2内层,与载体反应生成CuAl2O4的量明显增加。900℃焙烧催化剂,所有的Cu物种都以CuAl2O4形式存在。表明高温焙烧有利于CuO向CeO2内层迁移及内层CuO与载体Al2O3反应生成CuAl2O4。

CuO transference and thermal solid-solid interaction in CuO/CeO2-Al2O3 catalysts prepared by an impregnation method were characterized by in-situ XRD, Raman spectroscopy and H2-TPR techniques. For the catalyst calcined at 300 %, two kinds of CuO species coexist on the surface： highly dispersed and bulk CuO. Four kinds of CuO species present for the catalyst calcined at 600 ℃ ： （ 1 ） Highly dispersed CuO, （2） Bulk CuO on the surface, （3） Bulk CuO in the internal layer of CeO2, and （4） CuAl2O4 formed from CuO-Al2O3 interaction. For the catalyst calcined at 800℃, besides very little highly dispersed and bulk CuO on the surface, CuO has transferred into the internal layer mostly and the amount of CuAl2O4 is increased. At 900 ℃, all of CuO diffuseds into the internal layer of CeO2 and formes CuAl2O4. Experiment results show that the calcination temperature can promote transference of CuO from the surface into the internal layer and the CuO-Al2O3 interaction.