Amorphous magnesium substituted mesoporous aluminophosphate: An acid-base sites synergistic catalysis for transesterification of diethyl carbonate and dimethyl carbonate in fixed-bed reactor

摘要

Amorphous magnesium substituted mesoporous aluminophosphate (AlPO) were prepared, characterized and used as catalysts for the transesterification of diethyl carbonate and dimethyl carbonate in the fixed-bed reactor. The results of FT-IR and XPS confirm the substitution of Mg into the framework of AlPO. Magnesium substituted mesoporous aluminophosphate (MgAPO) have strong basic and weak acid sites according to the results of CO2-TPD and NH3-TPD. Compared with that of the ALPO catalyst, the pore diameters of the catalysts increased after the introduction of Mg. The activity and stability of the catalysts also improved with the introduction of Mg. The catalytic performance of these catalysts increases in the order of AlPO < Mg(0)(.1)APO < Mg(0)(.)(3)APO < Mg(0)(.)(2)APO, which is consistent with the strong basic and weak acid amounts of the catalysts, indicating an acid-base synergistic catalysis in the reaction. The catalyst showed high stability after 960 h of time on stream. As a result, the Mg(0.)(2)APO presented remarkable activity and durability in the synthesis of ethyl methyl carbonate from dimethyl carbonate and diethyl carbonate in fixed-bed reactor.