稀释气对甲醇在Ca/HZSM-5上制低碳烯烃的影响

使用连续流动固定床反应器，以2%Ca/HZSM-5为催化剂，考察水蒸汽、N₂、H₂和空气等作为稀释气对甲醇制烯烃催化活性稳定性、低碳烯烃选择性以及副产物的影响。低碳烯烃选择性和催化稳定性实验结果表明，水蒸汽较好，N₂、H₂次之，空气较差。水蒸汽条件下，催化活性稳定性大幅提高，甲醇完全转化时间5 000 min以上，丙烯选择性达52.3%。提高水蒸汽分压有利于甲醇制烯烃反应，水蒸汽分压（82.07~89.17） kPa时，催化剂稳定性较好，且低碳烯烃选择性高。实验结果还表明，即使稀释气中含有少量空气，对甲醇制烯烃反应的影响也较大，与空气中的效果接近。对不同稀释气的作用与机理进行了分析。

Effects of diluting gases on methanol to light olefins process over Ca/HZSM-5

Effects of diluting gases, i. e. , water vapor, nitrogen, hydrogen and air, on stability of the catalyst, selectivity to light olefins and byproducts for methanol to light olefins （ MTO ） over 2% Ca/ HZSM-5 were investigated in a continuous flow fixed-bed reactor. As a result of the selectivity to light olefins and catalyst stability, water vapor was the best diluent, followed by nitrogen and hydrogen, and air was the worst. Using water vapor as the diluent, catalyst stability was greatly enhanced, with the time for complete methanol conversion of longer than 5 000 min and selectivity to propylene of 52.3%. Increasing partial pressure of water vapor favored MTO reaction, with good catalyst stability and high selectivity to light olefins under water vapor partial pressure of （ 82.07 - 89.17 ） kPa. The experimental results also indicated that even a small portion of air in the diluent would impair MTO reaction to a extent similar to that of air diluent. The role and mechanism for different diluting gases were discussed.