论文部分内容阅读
制备了一系列脱铝超稳Y沸石(DUSY)负载的12-磷钨杂多酸(PW)及其铯盐催化剂,表征了其比表面和酸强度,并在乙酸和正丁醇液相酯化反应中考察了催化剂的活性、选择性和稳定性.结果表明,DUSY上引入PW后,酯化反应的催化活性明显提高,正丁醇的转化率从49.5%上升到86.4%,而PW的这种促进作用并未在超稳Y沸石负载的PW催化剂上观察到;DUSY负载磷钨酸铯盐催化剂(Cs2.5H0.5PW/DUSY)的转化率高达94.6%,且乙酸正丁酯的选择性为100%;催化剂稳定性考察表明,经过5次反复使用后,负载磷钨酸铯盐的催化活性仍高达81.6%,而相应的负载磷钨酸的催化活性却大幅度下降到47.6%;催化剂溶脱性研究表明,催化剂在反复使用过程中活性下降的量与活性组分在极性体系中的溶脱量成对应关系,说明催化剂活性下降的主要原因是杂多酸(盐)活性组分的流失造成的,而负载磷钨酸铯盐良好的催化稳定性来源于磷钨酸铯盐的难溶脱性.
A series of dephosphorized ultra-stable Y zeolite (DUSY) supported 12-phosphotungstic heteropoly acid (PW) and its cesium salt catalyst were prepared. Their specific surface and acid strength were characterized and esterified in the liquid phase of acetic acid and n-butanol The activity, selectivity and stability of the catalyst were investigated in the reaction.The results showed that the catalytic activity of esterification increased obviously after DUSY was introduced into PW, while the conversion of n-butanol increased from 49.5% to 86.4% The promoting effect was not observed on the ultra-stable Y zeolite loaded PW catalyst. The conversion of DUSY-supported cesium phosphotungstate catalyst (Cs2.5H0.5PW / DUSY) was as high as 94.6%, and the selectivity to n-butyl acetate Was 100%. The catalyst stability showed that the catalytic activity of cesium phosphotungstate was still up to 81.6% after 5 times of repeated use, but the catalytic activity of the corresponding supported phosphotungstic acid dropped sharply to 47.6%. The catalyst The results of dissolution study showed that the decrease of the activity of the catalyst during repeated use was related to the amount of the active component dissolved in the polar system, indicating that the decrease of the catalyst activity was mainly due to the loss of the active component of the heteropoly acid (salt) Caused by the good catalytic stability of cesium phosphotungstate loaded Insoluble in cesium salt of phosphotungstic acid detachable.