二氧化硅负载杂多酸铵催化苯液相硝化反应的研究

Nitration of Benzene Catalyzed by Ammonium Salt Catalysts of Heteropoly Acid Supported on Silicon Dioxide

以正硅酸乙酯为硅源,调整钼酸铵、钨酸铵用量,采用溶胶-凝胶法制备了二氧化硅负载磷钼钨杂多酸铵盐催化剂,利用XRD和IR对催化剂进行了表征,并以苯液相硝化反应为模型反应,初步评价了催化剂的苯硝化反应催化性能.结果表明,杂多酸铵具有典型的Keggin结构,而且表现出较强的苯硝化反应催化活性和100%单硝基苯选择性;钨含量的增大,可有效的增强催化剂的催化性能;催化剂可以重复使用,但使用5次后,催化活性相有所损失,导致催化活性下降.

A series of silicon dioxide supported ammonium salt catalysts of heteropoly acid with different mol ratios of Mo to W atom were prepared via sol-gel method,and their structures were verified by XRD and IR spectra,as well as their activities for liquid nitration of benzene to nitrobenzene were evaluated.Experiments results indicated that these ammonium salts had typical characters of Keggin structure,and these catalysts exhibited excellent catalytic activity for liquid nitration reaction.And the conversion of benzene was increased with the decrease of mol ratio of Mo to W atom.And the repetitive-use of catalyst was also evaluated,which indicated that the active component had some loss in the reaction progress.