PbO-TiO2 catalysts were prepared by sol-gel method and used in the transesterification of dimethyl carbonate and phenol.The catalysts were characterized by means of XRD and TPD.The effects of active component molar ratio,solution pH and calcination temperatures on the activities of the catalysts in the transesterification were investigated,and the transesterification reaction conditions were optimized.It was showed that the PbO-TiO2 catalyst with n(PbO) ∶ n(TiO2) of 1 ∶ 2,solution pH of 3.0 and calcination temperature of 500 ℃ had the best catalytic properties.When it was used in the transesterification,under the conditions of catalyst dosage 1％(w) and reaction distillation 5 h,the conversion of phenol and the selectivity to methyl phenyl carbonate reached 57.1％ and 98.5％,respectively.The characterization results showed that the PbO and Pb-Ti double metal oxides could improve the catalyst activity and the catalysts with many strong alkaline sites and moderate alkali concentration had the high catalytic activity.%采用溶胶凝胶法制备了PbO-TiO2催化剂,将其用于碳酸二甲酯与苯酚的酯交换反应,利用XRD和TPD对制备的催化剂进行表征,考察了催化剂活性组分的摩尔比、溶液pH、焙烧温度等催化剂制备条件对酯交换反应的影响,并优化了酯交换反应的条件.实验结果表明,在n (PbO)∶n(TiO2)=1∶2、溶液pH=3.0、焙烧温度500℃条件下制备的PbO-TiO2催化剂活性最高;催化剂用于碳酸二苯酯与苯酚酯交换生成甲基苯基碳酸酯的反应时,在催化剂用量为1％(w),反应精馏5h条件下,苯酚的转化率达57.1％,甲基苯基碳酸酯选择性达98.5％.表征结果显示,PbO和Pb-Ti双金属氧化物有利于提高催化剂的活性,表面强碱性位多,且碱浓度适中的催化剂活性最好.
展开▼
