SiW/ZrO_2/MCM-41催化苯甲醚酰化反应

采用逐层浸渍法制备了MCM-41介孔分子筛负载ZrO2及硅钨酸(SiW)催化剂,考察了催化剂在以苯甲醚为原料、乙酸酐为酰化试剂的Friedel-Crafts酰化反应中的催化活性,同时对催化剂进行XRD、N2吸-脱附测试、DSC、FTIR、NH3-TPD等表征,研究了ZrO2与SiW及载体之间的相互作用对催化剂活性的影响。实验结果表明,SiW直接负载到MCM-41后,SiW与载体发生相互作用使Keggin结构发生畸变,导致活性下降;但SiW通过ZrO2接枝负载到MCM-41后,SiW较好地分散在载体表面且保持了完整的Keggin结构,SiW与ZrO2间的相互作用增加了催化剂上强酸中心的数目,显著提高了催化活性。催化剂的最佳制备条件为:ZrO2负载量20%(w),SiW负载量60%(w),焙烧温度200℃;最佳反应条件为:反应时间4 h,反应温度110℃,催化剂用量为0.2 g(基于10 mmol乙酸酐),苯甲醚与乙酸酐的摩尔比10。

Friedel-Crafts Acylation of Anisole over SiW/ZrO2/MCM-41

MCM-41 molecular sieve supported tungstosilicic acid(SiW)/zirconia catalysts(SiW/ ZrO2/M) were prepared through impregnation and characterized by means of XRD,N2 adsorptiondesorption,DSC,FTIR and NH3-TPD.Their catalytic activities in the Friedel-Crafts acylation of anisole with acetic anhydride were investigated and compared to those of SiW directly supported on MCM-41(SiW/M) and bulk SiW.The effects of the interactions between ZrO2,SiW and the support on their catalytic activities were studied.The results showed that the catalytic activity of SiW/M was lower than that of bulk SiW,due to the distortion of SiW Keggin structure caused by the interaction between SiW and the support.However,when SiW was supported on ZrO2-grafted MCM-41,an obvious increase in catalytic activity was observed,which could be attributed to the increase of strong acidic sites on the catalyst surface due to the fine dispersion of SiW on the support and the interaction between SiW and ZrO2.The optimal preparation conditions for the SiW/ZrO2/M catalyst were:ZrO2 loading of 20%(w),SiW loading of 60%(w) and calcination temperature of 200 ℃.The optimal acylation reaction conditions were: reaction temperature of 110 ℃,reaction time of 4 h,catalyst dosage of 0.2 g(based on 10 mmol acetic anhydride),and mole ratio of anisole to acetic anhydride of 10.