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分别采用物理研磨、浸渍和共沉淀3种方法制备了负载型固体碱MgO/ZrO2催化剂,并将其用于催化碳酸二甲酯与异辛醇的酯交换反应合成碳酸二异辛酯。结果表明,催化剂的活性在焙烧温度为973 K时达到最佳,合成产物的收率分别为67.00%,51.00%,59.93%。催化剂的X射线衍射、CO2程序升温脱附、FTIR表征表明,催化剂的活性及稳定性取决于MgO/ZrO2的结构。四方氧化锆晶相对催化活性有积极的影响,当单斜氧化锆晶相明显时,催化活性显著下降。用物理研磨法制备的催化剂,由于MgO均匀分散于载体表面而使其显示高催化活性。用共沉淀法制备的催化剂,由于Mg2+进入Zr4+的晶格形成MgO/ZrO2固溶体结构,使其显示了高的稳定性和活性。
The supported solid alkali MgO / ZrO2 catalysts were prepared by physical milling, impregnation and coprecipitation, respectively, and were used to catalyze the transesterification of dimethyl carbonate and isooctanol to synthesize diisoctyl carbonate. The results showed that the activity of the catalyst reached the best when the calcination temperature was 973 K, and the yields of the synthesized products were 67.00%, 51.00% and 59.93% respectively. X-ray diffraction of catalyst, CO2 temperature-programmed desorption and FTIR characterization indicate that the activity and stability of the catalyst depend on the structure of MgO / ZrO2. The tetragonal zirconia crystal has a positive effect on the catalytic activity, and when the monoclinic zirconia crystal phase is obviously, the catalytic activity is significantly decreased. The catalyst prepared by the physical grinding method shows high catalytic activity because MgO is uniformly dispersed on the surface of the carrier. Coprecipitation prepared by the catalyst, as Mg2 + into the lattice of Zr4 + form MgO / ZrO2 solid solution structure, it shows high stability and activity.