硅钨杂多酸对乙酸异戊酯合成反应的催化性能

采用乙醚萃取法合成具有Keggin型结构的硅钨杂多酸（H4SiW12O40）,并采用浸渍法将硅钨杂多酸负载在二氧化硅载体上制备H4SiW12O40/SiO2,用IR对制备的催化剂进行表征,结果表明所制备的负载型催化剂中硅钨酸仍保留原有结构.将制备的H4SiW12O40和H4SiW12O40/SiO2用于乙酸异戊酯的合成反应,探讨合成乙酸异戊酯的最佳反应条件,以及所制备的催化剂对乙酸异戊酯合成反应的催化活性和重复使用性.结果表明：合成乙酸异戊酯的最佳酸醇摩尔比为1∶1.6,催化剂用量为1.500 g（约占反应物总质量的2.37%）.在该条件下,以H4SiW12O40为催化剂时乙酸的转化率在120 min可达到97.70%,以H4SiW12O40/SiO2为催化剂时乙酸的转化率在120 min可达到87.14%.负载型硅钨杂多酸H4SiW12O40/SiO2在使用后可以很容易地进行分离,并重复使用,是合成乙酸异戊酯的一种新型环境友好型催化剂.

Preparation of Silicotungstic Acid and Its Catalytic Activity in Isoamyl Acetate Synthesis

Silicotungstic acid(H4SiW12O40)was synthesized by ether extraction method,and H4SiW12O40/SiO2 was synthesized by impregnation method.Their structures were characterized by IR spectrum.The results show that both of them keep the Keggin-type structure.The catalytic activities of H4SiW12O40 and H4SiW12O40/SiO2 in isoamyl acetate synthesis were studied,and the optimum synthesis condition of isoamyl acetate was also studied.The results show that the optimum acid to alcohol ratio is 1∶1.6,the amount of the catalyst is 1.500 g(2.37 % of the total reactants).At this condition,the conversion of acetic acid reached 97.70 % in 120 min when H4SiW12O40 was used as catalyst and reached 87.14 % in 120 min when H4SiW12O40/SiO2 was used as catalyst.H4SiW12O40/SiO2 can be easily separated and reused.It is a new type of environment friendly catalyst for isoamyl acetate synthesis.