钒-铜复合氧化物催化碳酸二甲酯和苯酚酯交换合成碳酸二苯酯

V-Cu Composite Oxide Catalyst for Transesterification of Dimethyl Carbonate with Phenol to Diphenyl Carbonate

采用共沉淀法制备了一种用于碳酸二甲酯与苯酚酯交换合成碳酸二苯酯的新型钒-铜复合氧化物催化剂.考察了V/Cu配比对催化剂性能的影响以及催化剂的重复使用效果,并用X射线衍射对催化剂的结构进行了表征.结果发现,在焙烧温度为550℃,V∶Cu摩尔比为4∶1条件下制得催化剂的活性最高,该催化剂上苯酚的转化率为37.0%,甲基苯基碳酸酯及碳酸二苯酯的总选择性为96.8%.由X射线衍射表征结果可知,该催化剂的物相组成为V2O5和CuV2O6.催化剂使用三次后苯酚转化率从37.0%降至23.7%,多次重复使用后的催化剂在空气气氛中焙烧即可再生,再生催化剂的催化性能几乎和新鲜催化剂相当,其苯酚转化率达到36.2%.

The V-Cu composite oxide catalyst was prepared by coprecipitation and used for the synthesis of diphenyl carbonate （DPC） by transesterification of dimethyl carbonate （DMC） with phenol. The effect of the molar ratio of V/Cu and the reusability of the catalyst were investigated. The catalyst showed the highest activi- ty with a V/Cu molar ratio of 4/1. Under the conditions of 150-180 ℃ and 9 h, the conversion of phenol and the transesterification selectivity over the V-Cu catalyst were 37.0 % and 96.8 %, respectively. According to the X-ray diffraction results, the V-Cu composite oxide was composed of crystalline V205 and CuV206 at V/Cu = 4/ 1. Both crystalline V205 and CuV206 were the active phase. In addition, the activity of the catalyst was reduced from 37.0 % to 23.7 % after the catalyst was reused three times. However, the used catalyst could be easily regenerated by calcination at 550 ℃ in air for 5 h, and the catalytic activity of the regenerated catalyst was almost as high as that of the fresh sample.