通过沉淀、老化、过滤、洗涤、干燥、浸渍和焙烧等过程,由ZrOCl2和(NH4)2S2O8制备了S2O8^2-/ZrO2催化剂。用XRD,FT—IR,NH3-TPD对其进行了表征,研究了焙烧温度对其酸性、结构和催化性能的影响。XRD结果表明具有较高T型晶相峰。FT—IR分析表明S2O8^2-/ZrO2表面以双桥鳌合状配位化合物形式结合。研究了醛醇物质的量比、催化剂用量、反应时间等因素对产品收率的影响。结果表明,在n(丁醛)/n(乙二醇)=1:1.4,催化剂质量分数为0.25%,反应时间为50min的最佳条件下,丁醛乙二醇缩醛的收率可达95.8%;在n(苯甲醛)/n(乙二醇)=1:1.25,催化剂质量分数为0.5%,反应时间为50min的最佳条件下,苯甲醛乙二醇缩醛的收率可达88.8%。
The S2 O8^2-/ZrO2 solid acid catalyst was prepared from ZrOCl2 and (NH4)2S2O8 by precipitation, aging, filtering, washing, drying, impregnation and calcination processes. The characterization of the catalyst was performed using XRD, FT-- IR and NH3--TPD. The effect of calcination temperature on the acidic property, textural property and catalytic perfomance of S2 O8^2-/ZrO2 solid acid catalysts was studied. XRD patterns show that the catalyst present is higher tetragonal phase. FT--IR spectra shows that S2O8^2- is strongly bind with the ZrO2 surface bidentately. With S2 O8^2-/ZrO2 as catalyst, the effects of molar ratio of glycol to aldehyde, quantity of catalyst, reaction time on the yield of acetalation was more systematically studied and the best reaction conditions were confirmed. The results show that the molar ratio of butyraldehyde to glycol is 1 : 1.4, the quantity of catalyst is equal to 0.25% of feed stocks, the reaction time is 50 min, and the yield of butyraldehyde glycol acetal can reach 75.8 % ; the yield of benzaldehyde glycol acetal is 68.8% under the following conditions:molar ratio of benzaldehyde to glycol 1 : 1.25, the quantity of catalyst 0.5% of feed stocks, the reaction time 50 min.