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用原位合成法制备了不同固载量的磷钨酸催化剂HPW/SBA-15,通过FTIR、TEM、XRD、31PNMR及N2-吸附脱附等方法对催化剂进行表征。结果表明,在低固载量时,原位法制备的催化剂保持了SBA-15材料的长程有序结构,并且随着固载量的提高,孔径、比表面积等均有所下降;固载量达到33.3%时,SBA-15材料的长程有序结构遭到一定的破坏;在载体孔壁中高度分散的磷钨酸仍然保持了Keggin特征结构,且与SBA-15材料的表面羟基存在一定的化学相互作用。对苹果酯合成的催化性能研究表明,乙酰乙酸乙酯的转化率可以达到87%以上,催化剂使用6次后,催化活性仍保持在85%。
The HPW / SBA-15 catalysts with different loadings were prepared by in situ synthesis. The catalysts were characterized by FTIR, TEM, XRD, 31P NMR and N2-adsorption-desorption. The results showed that the catalysts prepared by in-situ method retained the long-range ordered structure of SBA-15 at low loading, and the pore size and specific surface area decreased with the increase of the loading. At 33.3%, the long-range order structure of SBA-15 material was destroyed. Phosphotungstic acid, which was highly dispersed in the pore wall, still retained the Keggin structure and had certain chemical interactions with the surface hydroxyl groups of SBA-15 effect. The catalytic performance of the synthesis of malic esters showed that the conversion of ethyl acetoacetate can reach more than 87%, and the catalyst activity remained at 85% after 6 times.