Catalyzed Transesterification Reaction Solid Base Design Synthesis And Catalytic Performance

The transesterification is an important reaction in synthesis of esters in industry. It is a hot point in present reseach using heterogeneous catalyst. As a novel solid base catalyst, the hydrotalcite-like compounds have been attracted more and more attention due to its good catalytic performance, tunable structure and low cost of raw materials.The condition to synthesize high alkaline hydrotalcite as solid base of transesterification with the tributyrin as a model reaction is discussed, the conditions of tributyrin transesterification is also optimized in this paper. The samples are characterized by XRD, SEM, nitrogen adsorption-desorption, and the results show that the Mg-Al hydrotalcite synthesized by low coprecipitation has higher crystallinity. The Mg-Al composite oxides exhibit the better catalytic activity in transesterification between tributyrin and methanol.Based on the above results, to improve the catalytic activity, the performance of different metal (Li, Ca and Sr) doped hydrotalcite and the influence of the calcined product on the transesterification is also studied. The alkaline of catalyst is improved when the doped is Li, Ca, Sr, and the mixing amount n(Mx+)/n(Mg2+)=0.5. The results of the CO2-TPD show that the alkaline and catalytic activity of catalyst are improved. MgLiAl-1c is the best catalyst.79.5%selectivity of methyl butyrate and 97.9% conversion of tributyrin when the amount of catalyst is 3wt%, reaction time is 5 h and reaction temperature is 60℃. However, using the hydrotalcite as catalyst, the corresponding selectivity and conversion are only 74.7%and 50.8%, respectively.The influences of hydrotalcite load alkali metal K, alkaline earth metal Ca, the activity of loaded K and Ca catalyst is studied, as well as the amount of loading for he transesterification are finally investigated. The results show that the hydrotalcite is an excellent support. The catalytic activity of transesterification increases with the amount of K and Ca. The n%K/MgAl-LDO series of the catalyst, when the loading is 30%, catalysts exhibit excellent catalytic activity. The transesterification is almost 100% when the loading of CaO is 20%.