钼-钛复合氧化物催化碳酸二甲酯和乙酸苯酯合成碳酸二苯酯

Mo-Ti Composite Oxide Catalyst for Transesterification of Dimethyl Carbonate and Phenyl Acetate to Diphenyl Carbonate

采用溶胶-凝胶法制备了用于碳酸二甲酯(DMC)与乙酸苯酯(PA)酯交换合成碳酸二苯酯(DPC)的钼-钛复合氧化物催化剂,考察了Mo/Ti物质的量的配比、反应条件等因素对催化剂性能的影响。结合比表面积(BET法)、X-射线衍射等测试技术对催化剂进行了表征。结果发现,在焙烧温度为500℃,nMo∶nTi=5∶2条件下制得的催化剂活性最高,在优化的反应工艺条件(t=4 h,θ=180℃,wcat/wPA=0.08,nPA/nDMC=2)下,DMC的转化率为74.0%,甲基苯基碳酸酯(MPC)及DPC的选择性分别为51.0%,45.5%。比表面积测试结果表明,TiO2的添加,增大了催化剂的比表面积,有利于催化反应的进行。X-射线衍射测试结果表明,钼-钛复合氧化物中,MoO3具有良好的结晶形态,为α-MoO3,没有发现TiO2、Mo-Ti复合氧化物新物种的结晶相,说明TiO2、Mo-Ti复合氧化物新物相为无定型化合物,并高度分散在整个复合氧化物体系中。

The Mo-Ti composite oxide catalyst was prepared by sol-gel method and used for the transesterification of dimethyl carbonate （DMC） and phenyl acetate （PA） to diphenyl carbonate （DPC）. The effect of the molar ratio of Mo/Ti and reaction conditions on the catalytic performance was investigated. The catalyst with a Mo/Ti molar ratio of 2.5 shows the highest activity. When the reaction is carried out at 180℃, with a molar ratio of PA to DMC of 2：1, the reaction time of 4 h, a catalyst amount of 0.08 （weight ratio to PA）, the conversion of DMC is 74.0%, and the selectivity of DPC and MPC is 45.5% and 51.0%, respectively. According to the surface and X- ray diffraction results, lager specific areas result in improved catalytic performance by the addition of TiO/. The Mo-Ti composite oxide is composed of α-MoO3 and highly dispersed amorphous titania and/or new crystal phase of Mo-Ti. composite oxide.