Abstract

The transformation of methanol into light olefins over ZSM-5 zeolites with different SiO₂/Al₂O₃ molar ratios (SAR) and phosphorus contents was investigated. An increase in the SAR and amount of incorporated phosphorus reduced the acid-site strength and density, which favored catalytic stability and the production of light olefins, mainly propylene. Under an isoconversion of 91%, high propylene/ethylene molar ratios were observed using the zeolite with the highest SAR (i.e., HZ(280)) and the one containing 4 wt.% P (i.e., 4PHZ(30)). However, the latter was less stable when used in a long-term reaction. An experimental design was employed to investigate how the reaction temperature and methanol partial pressure affect the propylene (C₃⁼) yield in the reaction catalyzed by the HZ(280) zeolite, which led to a temperature of 475 °C and a methanol partial pressure of 0.04 atm using the proposed model within the experimental design space.

摘要

_{研究了不同SiO 2} /Al ₂ O ₃摩尔比（SAR）和磷含量的ZSM-5沸石将甲醇转化为轻质烯烃。SAR 和掺入磷量的增加会降低酸位强度和密度，这有利于催化稳定性和轻质烯烃（主要是丙烯）的生产。在 91% 的等转化率下，使用具有最高 SAR 的沸石（即 HZ(280)）和含有 4 wt.% P 的沸石（即 4PHZ(30)）观察到高丙烯/乙烯摩尔比。然而，后者在用于长期反应时不太稳定。采用实验设计来研究反应温度和甲醇分压如何影响丙烯（C ₃⁼ ) 由 HZ(280) 沸石催化的反应中的产率，在实验设计空间内使用所提出的模型导致温度为 475 °C，甲醇分压为 0.04 atm。