Cu+/SiO2-ZrO2催化剂的制备及其催化甲醇氧化羰基化性能

摘要

Silica-zirconia mixed oxide (SiO2-ZrO2) was synthesized by sol-gel method; with SiO2-ZrO2 as the support, CuCl2/SiO2-ZrO2 catalyst was then prepared by ion-exchange and used in the liquid oxidative carbonylation of methanol to dimethyl carbonate (DMC). The results showed that the introduction of zirconium species into the amorphous silica leads to the formation of Si-O-Zr bonds and Br()nsted acid sites. When the CuCl2/SiO2-ZrO2 catalyst is calcined at 300 ℃ ～550 ℃ in an inert atmosphere, CuCl2 is dispersed and bounded on the surface of SiO2-ZrO2 support; CuCl2 can be auto-reduced to CuCl, which is then ion-exchanged with the surface Br()nsted acid sites of the SiO2-ZrO2 support to form Cu+ species. As a result, most of copper remains to be highly dispersed on the surface of SiO2-ZrO2 and only a small amount of chlorine is left over. The CuCl2/ SiO2-ZiO2 catalyst calcined at 450 ℃ exhibits excellent activity in the oxidative carbonylation of methanol; under the conditions of 140 ℃, 2.4 MPa and a CO/O2 ratio of 2, the conversion of methanol and the selectivity to DMC reach 10.0％ and 79.4％, respectively.%采用溶胶-凝胶法制备了SiO2-ZrO2复合氧化物载体,通过和CuCl2进行离子交换制备了Cu+/SiO2-ZrO2催化剂,并研究其催化甲醇液相氧化羰基化合成碳酸二甲酯性能.结果表明,Zr以离子形式进入无定型SiO2骨架结构中形成Si-O-Zr键,同时产生较强的B酸中心.CuCl2通过热处理自还原为CuCl分散在SiO2-ZrO2载体表面,并与载体表面B酸发生离子交换形成Cu+物种,从而保留了活性金属组分Cu,脱除大部分的Cl元素.改善催化剂失活和设备腐蚀等问题.当焙烧温度为450℃时,催化剂表现出良好的催化活性,CH3OH转化率、DMC选择性和时空收率分别达到10.O%、79.4%和1.45G/(g·h).