Ni(OCH3)2/SiO2催化剂的制备及其合成碳酸二甲酯的反应性能

采用表面改性和离子交换相结合的方法，制备了负载型单核金属甲氧基配合物Ni(OCH3)2/SiO2催化剂。利用IR、TPD、TPSR和微反技术，考察了催化剂的表面结构以及CO2、CH3OH在催化剂表面上的化学吸附和反应性能。结果表明，负载型单核金属甲氧基配合物Ni(OCH3)2/SiO2中，Ni^2 与载体SiO2表面的O^2-以双齿形式配位；在催化剂表面存在CO2的桥式吸附态和甲氧碳酸酯基物种两种吸附态，CH3OH则只有一种分子吸附态。在373-473K条件下，CO2和CH3OH在催化剂上的反应物主要是DMC、H2O以及少量的CO、CH4和CH2O，催化剂的活性由表面甲氧碳酸酯基物种与分子吸附态甲醇的反应决定的。讨论了催化剂上CO2和CH3OH的活化过程及吸附态的形成机理。

Preparation of Ni(OCH3)2/SiO2 Catalyst and it's Reactivity for DMC Synthesis

The supported mononuclear nickel methoxide complex, Ni(OCH\-3)\-2/SiO\-2 was prepared by surface reaction modification and ion\|exchange method. Surface structure, chem\|adsorption and reactivity of the catalyst were characterized by IR, TPD, TPSR and microreactor techniques. The results showed that Ni\+\{2+\} bonds with O\+\{2-\} of the SiO\-2 support in bidentate fashion and is terminated with the two methoxyl groups. CO\-2 chemisorbs on the catalyst as two states: bridged absorption state and methyl carbonate species while CH\-3OH only formed molecular adsorption states. Reaction products were mainly DMC and H\-2O with few CO, CH\-4 and CH\-2O at 373~473 K. The reactivity was determined by surface methoxyl carbonate species and CH\-3OH in molecular adsorption states. Moreover, the activation processes of CO\-2 and CH\-3OH were analyzed theoretically.