Controlling the SAPO-34 Particle Size to Enhance Reaction-Diffusion Behavior for Improving Catalytic Efficiency in the MTO Reaction
Controlling the SAPO-34 Particle Size to Enhance Reaction-Diffusion Behavior for Improving Catalytic Efficiency in the MTO Reaction
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DOI：
10.1021/acs.iecr.3c00555
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
Jiaxin Wu;Ruizhi Chu;Xianliang Meng;Bangming Yang;Pengcheng Li;Mingzhi Dai;Guoguang Wu;Xiao Li;Xiao F. Jiang;Weisong Li
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文献类型：
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作者：
Jiaxin Wu;Ruizhi Chu;Xianliang Meng;Bangming Yang;Pengcheng Li;Mingzhi Dai;Guoguang Wu;Xiao Li;Xiao F. Jiang;Weisong Li
SAPO-34分子筛作为一种重要的催化剂在甲醇制烯烃反应中得到了广泛的应用，但其反应物甲醇的内扩散行为的研究仍然是一个挑战。制备了一系列不同粒径的SAPO-34催化剂，其中当TEAOH/莫尔比为8：1时，可合成出薄层状SAPO-34分子筛，其低碳烯烃选择性高达95%，寿命长达410 min。结合失活催化剂的TG和BET结果，发现积炭堵塞了催化剂的孔道是催化剂失活的主要原因。动力学结果表明，沸石的粒径与其表观反应速率成反比。Thiele模量的计算表明，小颗粒分子筛的分子内扩散速率较快。由于内扩散被部分消除和酸性中心的利用率提高，可以通过减小颗粒尺寸来提高催化效率。
The SAPO-34 zeolite as an important catalyst is widely used in the methanol-to-olefin reaction, but understanding the internal diffusion behavior of its reactant methanol is still a challenge. In this work, a series of SAPO-34 catalysts with different particle sizes were prepared, among which the thin-layer SAPO-34 zeolite could be synthesized when the ratio of TEAOH/Mor is 8:1, which exhibits a high selectivity of 95% for light olefins and a long lifetime of 410 min. Through29Si NMR and N2physical adsorption–desorption, it indicates that more Si(4Al) coordination structures and a larger external volume jointly determine the stability of SAPO-34. Combining the TG and BET results of deactivated catalysts, it was found that the main reason for deactivation is the micropore blocked by coke deposition. The kinetic results demonstrated that the particle size of the zeolite is inversely proportional to its apparent reaction rate. The calculation of the Thiele modulus shows that the intramolecular diffusion rate of the small particle zeolite is faster. The catalytic efficiency can be enhanced by reducing the particle size due to the partly removed internal diffusion and the improved utilization of acid sites.