论文部分内容阅读
本文用TPD技术与红外光谱法研究了甲醇与烯烃在HSW与PHZSM-5上的吸附及甲醇的催化转化。观察到甲醇转化的产物分布与催化剂表面结构OH 基(3608cm~(-1))附近的吸收峰强度,B 酸中心的数目及其强度有直接关联。强的B 酸中心的数目较多、且能使甲醇与烯烃产生强烈的化学吸附而生成烷氧基的催化剂HZSM-5有利于生成汽油产物。反之,则有利于生成低碳烯烃。HSW 沸石表面结构OH 基的数目虽然很多,但是与HZSM-5相比,其表面强的B 酸中心的数目却较少,对甲醇与烯烃的化学吸附较弱,故有利于低碳烯烃的生成。另外,在高温下HSW 与PHZSM-5孔道中所生成的芳烃与聚合物的二次裂解也会使产物中富产烯烃。
In this paper, the adsorption of methanol and olefins on HSW and PHZSM-5 and the catalytic conversion of methanol were studied by TPD and FT-IR. It is observed that the product distribution of methanol conversion is directly related to the intensity of the absorption peak near the OH group (3608 cm -1) on the catalyst surface and the number of B acid centers and their intensity. HZSM-5, which has a large number of strong acid sites and a strong chemisorption of methanol and olefins to generate alkoxy groups, is good for generating gasoline products. On the contrary, it is conducive to the production of light olefins. Although the number of OH groups on the surface structure of HSW zeolite is quite large, the number of strong B acid centers on the surface of the HSW zeolite is smaller than that of HZSM-5, and the chemisorption on methanol and olefin is relatively weak, which is in favor of the formation of light olefins . In addition, secondary cracking of aromatics and polymers generated in the HSW and PHZSM-5 channels at elevated temperatures also results in the production of olefins in the product.