AlH3P2W18O62?nH2O/MCM-41的制备、表征及催化合成阿斯匹林性能研究

Preparation，characterization of AlH3P2W18O62?nH2O/MCM-41 and its activity on catalytic synthesis of aspirin

摘要:

通过浸渍法制备了MCM-41负载Dawson型磷钨酸铝催化剂（Al2P2W18O62?nH2O/MCM-41），并用于催化合成阿司匹林，采用FT-IR、XRD、SEM、EDX、NH3-TPD、Py-IR、N2-TPD及TG-DSC对其结构进行表征。探讨了磷钨酸铝负载量、催化剂用量、水杨酸与乙酸酐摩尔比、反应时间、反应温度及催化剂重复使用次数对阿司匹林收率的影响。结果表明：AlH3P2W18O62?nH2O均匀地负载在MCM-41载体上，负载后仍保持Dawson结构。与AlH3P2W18O62?nH2O相比，负载型催化剂（30%Al2P2W18O62?nH2O/MCM-41）呈“蜂巢状”，比表面积明显增大、热稳定性提高，同时具有Lewis酸中心和Br?nsted酸中心，但酸强度降低。在优化反应条件下：即AlH3P2W18O62?nH2O负载量为30%，w（30% AlH3P2W18O62?nH2O/MCM-41）=4.1%（基于反应物的质量），水杨酸与乙酸酐摩尔比1:1.5，80℃反应30min，产物收率为96.3%。催化剂可重复使用，第6次使用时阿司匹林收率达80.6%。30% AlH3P2W18O62?nH2O/MCM-41具有良好的催化活性和稳定性。

Abstract:

A series of dawson type aluminiumphosphotungstates supported on MCM-41 molecular sieve（AlH3P2W18 O62?nH2O/MCM-41）were prepared by immersion process and was used in the synthesis of acetylsalicylic. The structures of catalysts were characterized by FT-IR, XRD, SEM , EDX, BET, NH3-TPD,N2-TPD and TG-DSC. Influences of amount of AlH3P2W18O62?nH2O loading, dosage of catalyst, the mole ratio of reactants, reaction temperature, reaction time and reusability of catalyst on the reaction were investigated. The results indicated that the AlH3P2W18O62?nH2O was evenly loaded on the MCM - 41 carrier and existed in the form of Dawson structure. Compared with AlH3P2W18O62?nH2O, the high specific surface area and thermal stability of supported catalyst (30% AlH3P2W18O62?nH2O/MCM-41) increased, but the acid strength of supported catalyst reduced. The supported catalyst showed honeycomb shape and had both Br?nsted and Lewis acid centers. Under the optimal conditions,i.e, loading amount of AlH3P2W18O62?nH2O of 30%, w (30% AlH3P2W18 O62?nH2O/MCM-41）=4.1% (relative to the dosage of total reactant), reaction temperature of 80℃, reaction time of 30 min, the yield of aspirin could reach 96.3%. The catalyst has good reusability and the yield of aspirin could reach 80.6% after six cycles. 30% AlH3P2W18 O62?nH2O /MCM-41 is the efficient and environmental friendly catalyst in synthesizing aspirinwith good catalytic activity and reusability.