杂多酸(盐)催化环己酮氨肟化反应

 制备了4种杂多酸并用红外光谱对其进行了表征，研究了它们及其负载型催化剂对环己酮氨肟化反应的催化性能，并以磷钨酸为催化剂，考察了催化剂用量、反应温度、反应时间、H2O2用量、氨水用量和溶剂种类对环己酮氨肟化反应转化率和环己酮肟选择性的影响。结果表明，所制备的4种杂多酸均具有Keggin型结构。以水为溶剂时，4种杂多酸对环己酮氨肟化反应均具有催化活性，其中磷钨酸的催化活性最高。在m(H3PW12O40)/m(C6H10O)为0.3、n(H2O2)/n(C6H10O)为1.6、n(NH3)/n(C6H10O)为3.0、20℃下反应5h的条件下，环己酮氨肟化反应的转化率为90.88%，环己酮肟选择性达98.38%。在相同的反应条件下，负载型磷钨酸催化剂中，以活性Al2O3为载体的磷钨酸催化剂环己酮氨肟化反应的催化活性最高，环己酮转化率为87.60%，环己酮肟选择性达到97.45%。

CATALYTIC ACTIVITY OF HETEROPOLY ACIDS(SALTS)FOR AMMOXIMATION OF CYCLOHEXANONE

Four heteropoly acid(salts) were synthesized and characterized by FT-IR. The catalytic activity of the synthesized heteropoly acids(salts) and their supported catalysts for the ammoximation reaction of cyclohexanone were estimated. The effects of the catalyst dosage, reaction temperature, reaction time, the dosage of H2O2 and NH3, solvent type on the conversion and cyclohexanone oxime selectivity of cyclohexanone ammoximation over phosphotungstic acid were inverstigated. The results revealed that all the four heteropoly acids possessed the Keggin-type structure and better catalytic activity in the ammoximation reaction of cyclohexanone with water as solvent, in which phosphotungstic acid was the best. Under the reaction conditions of m(H3PW12O40)/m(C6H10O)=0.3, n(H2O2)/n(C6H10O)=1.6, n(H2O2)/n(C6H10O)=3.0, 20℃,5 h, the cyclohexanone conversion and cyclohexanone oxime selectivity of the cyclohexanone ammoximation reached 90.88% and 98.38% respectively. Under the same reaction conditions as above mentioned the supported phosphotungstic acid catalysts also showed better catalytic activity in cyclohexanone ammoximation, in which the Al2O3-supported phosphotungstic acid catalyst was the best one with cyclohexanone conversion of 87.60% and cyclohexanone oxime selectivity of 97.45%.