HZSM-5沸石上酯化反应的研究

以醋酸和乙醇的酯化为典型反应,讨论了一系列HNaZSM-5沸石的阳离子交换度对酯化活性和选择性的影响,并与不同交换度的HNaZSM-5沸石的TPD酸性测定结果进行了关联。考察了不同温度焙烧的HZSM-5对酯化活性和选择性的影响,并与不同温度焙烧的HZSM-5沸石吸附吡啶的红外光谱进行了关联。结果表明,酯化反应既可以在B酸中心上进行,亦可以在L酸中心上进行;而乙醇分子间脱水主要是在B酸中心上进行。有机胺中毒实验的结果证明,酯化反应主要是在HZSM-5沸石的内表面上进行的。

Study of the Esterification Reaction of Acetic Acid by Alcohol on HZSM-5 Zeolite

It is reported the esterification reaction of acetic acid with alcohol on HZSM -5 zeolite. With a series of HNaZSM-5 zeolite catalysts, the effect of the degree of cation exchange on the activities and the selectivities of the catalysts were discussed. The effect of calcination temperature of HZSM-5 zeolite on the activity and the selectivity was investigated. The surface acidity of HZSM-5 zeolite was determined by JR-spectroscopic method. It Was found that the esterification reaction can take place both at the Bronsted acid sites and the Lewis acid sites, while ether was produced mainly at strong Bronsted acid sites. Since the activity of the catalyst was not reduced remarkably by 4-mcthylquinoline, the esterification must mainly occured on the internal surface of zeolite.