甲醇气相氧化羰化合成碳酸二甲酯 Ⅲ.复合载体铜基催化剂的表征

Synthesis of Dimethyl Carbonate via Gas-Phase Oxidative Carbonylation of Methanol Ⅲ.Characterization of Cu Composite Supported Catalyst

采用X射线衍射、表面物理吸附、CO原位吸附红外光谱、X射线光电子能谱以及热重分析方法对甲醇直接气相氧化羰化合成碳酸二甲酯的复合载体铜基催化剂(Cu(Ⅱ)/Naβ-AC)的物化性能进行了表征。实验结果表明,微波辐射条件下制备的Cu(Ⅱ)/Naβ-AC催化剂中,活性组分CuC l2一方面与分子筛载体间发生了固相离子交换反应,并形成了铜分子筛物种,另一方面,可直接高度分散在复合载体表面。反应后Cu(Ⅱ)/Naβ-AC催化剂中部分Cu2+被还原为Cu+或Cu0,Cu2+的结合能峰向低结合能方向迁移,但微波辐射处理并未破坏分子筛载体的骨架结构。采用复合载体增加了催化剂的比表面积,并产生一定量的微孔,从而提高了催化剂的氧化羰化反应活性。热重分析表明,当温度低于350℃时,Cu(Ⅱ)/Naβ-AC催化剂稳定性较好。

Copper -based catalyst on Naβ - AC （ active carbon） composite support （ Cu （ Ⅱ）/Naβ - AC ） for oxidative carbonylation of methanol into dimethyl carbonate were characterized by means of XRD, surface physical adsorption, in situ CO - adsorption FrIR, XPS and TG. Results showed that ion - exchange reaction between active component and zeolite support was carded out in solid phase, and the formed copper -containing zeolite species was the very active species for methanol oxidative carbonylation. The bivalent copper was partly reduced into univalent or metallic copper after reaction, with transition of Cu （ Ⅱ ）binding energy from higher to lower level. Framework of zeolite support was not destroyed under microwave radiation preparation condition. Specific surface area and micropores of catalyst increased by using composite support, and activity of catalyst for oxidative carbonylation was thus improved. In addtion ,Cu -based composite support catalyst Cu（ Ⅱ ）/Naβ -AC was heat -stable below 350 ℃.