甲醇制丙烯反应催化剂积炭行为的原位漫反射红外光谱研究

Coking Process of Catalyst Based on In-Situ Diffuse FT-IR Spectroscopy in Reaction of Methanol to Propene

基于催化剂固体表面吸附态物种产生红外信号的机理,借助原位漫反射傅里叶变换红外光谱研究甲醇制丙烯(MTP)反应催化剂在不同操作条件下的积炭行为,分别考察了4种不同性质的ZSM-5催化剂在不同反应温度的甲醇制丙烯(MTP)反应中的积炭历程。实验结果表明,随着反应温度的升高或反应时间的延长,催化剂上积炭组分中多环芳烃等重组分比例均提高。磷改性或水热处理使ZSM-5催化剂的孔道结构、酸性位点及其分布发生改变,从而使催化剂上积炭物质的种类增多,多环芳烃等重组分比例升高。相同操作条件下,催化剂强酸位的酸强度越高,其积炭量越大,并在反应后期积炭速率相对较快。

Based on the mechanism that the chemical substance adsorbed on catalyst surface can produce infrared signals,the method of in situ diffuse reflectance infrared Fourier transform spectroscopy（in situ DRIFTS） was used to study the behavior of catalyst coking in the reaction of methanol to propene（MTP）.The coke processes of four different ZSM-5 catalysts during MTP reaction at different temperatures were investigated.The results showed that the percentage of polycyclic aromatic hydrocarbons in the coke on catalyst increased with the increases of reaction temperature and time.Phosphorus-modification and hydro-thermal treatment could change the pore structure and acid sites of ZSM-5 catalyst,so both the species of coke deposition on the modified ZSM-5 catalyst and the percentage of polycyclic aromatic hydrocarbons in coke increased under the same MTP reaction conditions.In addition,the higher the acidity of strong acid site of catalyst,the more the amount of coke deposition and the faster the coking speed at the latter stage of reaction.