ZrO2-SiO2复合物表面酸性的调控及催化四氢呋喃聚合性能研究

Adjustment of Surface Acidity of ZrO_2-SiO_2 Mixed oxide and Catalytic Performance in Tetrahydrofuran Polymerization

采用醇-水溶液加热法制备了复合均匀的ZrO2-SiO2复合氧化物,通过调整复合物中ZrO2含量及焙烧温度对ZrO2-SiO2复合氧化物表面酸量及酸类型进行精细调控,并将其应用于催化四氢呋喃(THF)开环聚合反应.结果表明,当ZrO2含量小于30 mol%时,随着ZrO2含量的增加,复合物总酸量显著增加,且B酸与L酸酸量之比接近1∶1.当ZrO2含量增至50 mol%时,复合物总酸量增加不明显,但B酸酸量减少而L酸酸量显著增加.经高温焙烧后复合物孔径逐渐增大而孔容逐渐减少;复合物总酸量逐渐减少,但L酸百分含量逐渐增多.在催化THF聚合反应中所制备复合物均表现出较好的催化活性,ZrO2含量为50 mol%的复合物经1173 K焙烧后显示出较大的孔径,催化活性最高,聚合物收率达46.38%.

A series of highly homogenous ZrO2-SiO2 mixed oxide were obtained via alcohol-aqueous heating method.The effects of the content of ZrO2 and calcination temperature on the acid properties of ZrO2-SiO2 mixed oxides,including acid amount and acidic type,were investigated.Catalytic performances of these materials were examined for the polymerization of tetrahydrofuran（THF）.When ZrO2 content in mixed oxide was smaller than 30 mol%,the amount of total acidity of mixed oxides increased obviously as ZrO2 content increased,moreover,the mole ratio of Brnsted acidity and Lewis acidity was almost 1∶1.When ZrO2 content in mixed oxide was up to 50 mol%,the amount of total acidity increased slightly,the amount of Brnsted acidity decreased and Lewis acidity increased evidently.After the calcination at higher temperature the average pore size of mixed oxide increased wherever pore volume decreased.Besides,the amount of total surface acidity decreased but the proportion of Lewis acidity increased.The polymerization of THF indicated that all of the mixed oxide showed good catalytic performance.The mixed oxide with ZrO2 content of 50 mol% calcined at 1173 K had larger pore size and the highest polymer yield of 46.38%.