Characterization of CuO Species and Thermal Solid-Solid Interaction in CuO/CeO_2-Al_2O_3 Catalyst by In-Situ XRD,Raman Spectroscopy and TPR

摘要

Transference of CuO species and thermal solid-solid interaction in CuO/CeO_2-Al_2O_3 catalyst prepared by an impregnation method were characterized by in-situ XRD, Raman spectroscopy and H2-TPR techniques. For the catalyst calcined at 300 deg C , two kinds of CuO species coexist on the surface, that is, highly dispersed and bulk CuO crystalline phase. Four kinds of CuO species are present for the catalyst calcined at 600 deg C : (1) highly dispersed CuO, (2) bulk CuO on the surface, (3) bulk CuO in the internal layer of CeO_2, and (4) CuAl_2O_4 formed from CuO-Al_2O_3 interaction. For the catalyst calcined at 800 t, besides very little highly dispersed and bulk CuO on the surface, most of the CuO has transferred into the internal layer of CeO_2 and the mass of CuAl_2O4 are increased. At 900 deg C , all of CuO has diffused into the internal layer of CeO_2 and formed CuAl_2O_4. The results show that the distribution of CuO species in the catalysts depends on the calcination temperature; the different CuO species can be effectively confirmed by in-situ XRD, Raman spectroscopy and H_2-TPR techniques.