低温陈化法制备SO_4^(2-)/ZrO_2-Sm_2O_3固体超强酸及表征

Preparing by Ageing at Low Temperature andCharacterizing of SO_4^(2-)/ZrO_2-Sm_2O_3 Solid Superacid

本研究以氨水、氧氯化锆和三氯化钐为原料,用共沉淀法制得锆和钐的氢氧化物,经低温陈化、过滤、烘干和高温焙烧,制备出SO_4^(2-)/ZrO_2-Sm_2O_3固体超强酸(以下简称SZS)。用流动指示剂法测定其酸度,用IR、XRD对其进行了表征,并将其用于催化氯乙酸和乙醇的酯化反应。结果表明,低温陈化样品的突出优点是酸强度大(H0<-14.5);与SO42-结合得牢;在较宽的温度范围内,具有催化活性的亚稳态的ZrO2四方晶相没有发生相转变,这是其催化活性较高的微观原因。

The zirconic and samaric hydroxide were prepared by coprecipitation in ammonia with ZrOCl2 and SMCl3 in this research. The SO42-/ZrO2-SM2O3 solid superacid samples were obtained finally through the steps of ageing at low temperature, filtration, drying, impregnation and calcination. The acidity of samples were determined with flow indicator method, and the characterizations of the samples were performed by IR and XRD. The samples were used in the esterification of choroacetic acid and ethyl alcohol as the catalysts to study their catalytic performances. The results show that the sample ageing at lower temperature have best performances comparing with others samples aged at normal temperature, the acidic density is larger (H-0 < - 14.5), they could combine with SO42- more firmly, and the metastable tetragonal phase of ZrO2 crystal has not transformed into other phase through the wide temperatures. It is responsible for the higher catalytic activity as we believe.