NiO-Zr_xCe_(1-x)O_2催化剂的制备及其性能

Preparation and Perfomance of NiO-Zr_xCe_(1-x)O_2 Catalysts

用尿素均匀沉淀法制备了NiO-ZrxCe1-xO2复合氧化物,并用XRD、TPR、TPD和原位红外对其晶相结构、NiO与载体的相互作用、催化剂的表面酸碱性能和NiO-ZrxCe1-xO2对CO2和CH3OH吸附性等进行了表征。结果表明,Zr0.7Ce0.3O2形成固溶体,且表面具有酸性中心和碱性中心,除NiO-Zr0.1Ce0.9O2样品外,各催化剂均能使CH3OH发生解离吸附,而CO2在各催化剂表面发生了单齿吸附,在金属位上发生了线式吸附和剪式吸附,在金属位和酸性位的协同作用下发生了卧式吸附。NiO-Zr0.7Ce0.3O2催化剂在CO2和CH3OH常压合成碳酸二甲酯(DMC)反应中表现出较好的催化活性和选择性。

NiO- ZrxCe1-xO2 complex oxides catalysts are prepared by homogeneous precipitation method with urea as precipitant. XRD, TPR, TPD, and in-situ IR techniques are carried out to characterize the crystalline structures, interaction between NiO and the supports, the acid-base properties of catalysts and the adsorptions of CH3OH and CO2. The results show that Zr0.7Ce0.302 sample is solid solution structure, with acid site and base site on the surface. The dissociative adsorptions of CH3 OH is observed on the surface of catalysts except the Ni -Zro. 1Ce0.902 sample. Monodentate adsorption of CO2 occurs on the catalysts surface while linear and shearing adsorption of CO2 happen on the metallic sites. Besides, there is horizontal adsorption of CO2 with the synergistic function of meteallic sites and surports. The NiO -Zr0. 7 Ce0. 302 catalysts demonstrate high catalytic activity and selectivity in the synthesis of dimethyl carbonate from carbon dioxide and methanol.