After 5 reaction cycles,the catalytic activity of 30%PW/DUSY catalyst drastically dropped to 31.2%,in contrast,30%Cs_ 2.5H_ 0.5PW/DUSY catalyst still showed a considerable conversion of 88.2%.

• 经过5次反复使用后；负载型磷钨酸铯盐催化剂的催化活性仍较高；转化率达88.；2%25；而相应的负载型磷钨酸催化剂的催化活性却大幅度下降；转化率仅有31