Cu+/SiO2-ZrO2催化剂的制备及其催化甲醇氧化羰基化性能

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10.0%、79.4%和1.45g/(g·h)。

Preparation of Cu~+/SiO_2-ZrO_2 catalysts for oxidative carbonylation of methanol to dimethyl carbonate

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-ZrO₂ catalyst calcined at 450℃ exhibits excellent activity in the oxidative carbonylation of methanol; under the conditions of 140℃, 2.4MPa and a CO/O₂ ratio of 2, the conversion of methanol and the selectivity to DMC reach 10.0% and 79.4%, respectively.