中空介孔氧化硅球负载钛酸铋催化碳酸二甲酯与苯酚酯交换合成碳酸二苯酯

Transesterification of dimethyl carbonate with phenol to diphenyl carbonate catalyzed by hollow mesoporous silica sphere supported bismuth titanate

采用浸渍法合成了中空介孔氧化硅球负载钛酸铋系列催化剂,并用于苯酚与碳酸二甲酯酯交换合成碳酸二苯酯的反应。采用XRD、SEM、N_2吸附-脱附、XPS等方法对载体及系列催化剂进行表征。实验结果表明,在钛酸铋负载量30%(w)、催化剂用量0.8 g、150～180℃、反应9 h的优选条件下,苯酚转化率可达46.7%、酯交换选择性为99.6%;连续使用5次后,苯酚转化率由28.8%降低到24.7%。表征结果显示,少量的钛酸铋流失是催化剂活性下降的主要原因;与未负载的钛酸铋相比,负载型钛酸铋在介孔氧化硅球上高度分散,提供了更多的活性位,催化剂活性提高;中空介孔氧化硅的壳能够减少活性组分的流失。

Hollow mesoporous silica sphere supported bismuth titanate catalysts were prepared through the impregnation method,and used in the transesteri?cation reaction of dimethyl carbonate and phenol to diphenyl carbonate. The support and the catalysts were characterized by XRD,SEM,N2 adsorption-desorption,and XPS. The experiment results showed that under the optimized conditions of bismuth titanate loading 30%(w),catalyst amount 0.8 g,reaction temperature 150-180 ℃,reaction time 9 h,the phenol conversion reached 46.7% and the transesteri?cation selectivity was 99.6%.In recycle test,the phenol conversion decreased from 28.8% to 24.7% after ?ve runs. The characterization results showed that the leaching of a small amount of bismuth titanate was the main reason for the decline of catalytic activity. Compared with unsupported bismuth titanate,the bismuth titanates in the supported catalysts were highly dispersed on the hollow mesoporous silica spheres,providing more active sites,so the catalytic activity was enhanced. In addition,the shell of the hollow mesoporous silica spheres could prevent the leaching of active components.