Preparation, Characterization and Catalytic Behavior of 12-Molybdophosphoric Acid Encapsulated in the Supercage of Cs^＋-exchanged Y Zeolite

In order to solve the serious leaching problem of supported heteropoly acid catalysts in polar reaction media,12-molybdophosphoric acid encapsulated in the supercage of Cs+-exchanged Y zeolite was prepared by the "ship in the bottle" synthesis.The influence of ion-exchange conditions and the synthesis parameters on the encapsulation of PMo12 were investigated.The obtained solid sample was characterized by X-ray diffraction(XRD),31P magic angle spin nuclear magnetic resonance(MAS NMR) and Fourier Transform Infrared Spectroscopy(FT-IR),and its catalytic activity in the esterification of acetic acid and n-butanol was tested.The ion-exchange time,concentration of aqueous Cs+ solution,pH value,and amount of Mo added in the synthesis mixture were revealed to influence the encapsulation very remarkably.Under the optimal conditions,12-molybdophosphoric acid could be successfully encapsulated in the supercage of CsY zeolite,and the samples showed considerable catalytic activity and excellent reusability in the esterification reaction.

NaY沸石超笼中合成12-钼磷杂多酸

针对负载杂多酸催化剂在极性反应体系中活性组分易溶脱的难题,用"瓶中造船(ship in the bottle)"的方法在NaY沸石超笼中合成了12-钼磷酸.将机械混和的MoO3晶体和NaY沸石在高温下焙烧,使MoO3在沸石表面高度分散,以此复合物在磷酸水溶液中反应,得到的固体样品用X射线衍射仪(XRD)、31P核磁共振谱(31PNMR)和红外光谱(IR)进行了表征,并测试了其在醋酸和正丁醇的酯化反应中的催化性能.结果表明,MoO3质量分数为10%的MoO3/NaY中载体仍保持Y沸石的结构,以此为原料合成的样品呈现出Keggin结构杂多酸的红外特征峰,并且在核磁共振磷谱中杂多酸的化学位移峰向负值方向发生了较大程度的位移,说明杂多阴离子与Y沸石羟基发生了强相互作用,样品在醋酸与正丁醇的酯化反应中显示出了较高的催化活性和优异的重复使用性能.这些充分说明在NaY沸石超笼中成功合成了12-钼磷酸。