Microfibrous-Structured SS-fiber@meso-HZSM-5 Catalyst for Methanol-to-Propylene: Steam-Assisted Crystallization Synthesis and Insight into the Stability Enhancement

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• 作者：Jia Ding ; Pengjing Chen ; Songyu Fan ; Zhiqiang Zhang ; Lupeng Han ; Guofeng Zhao ; Ye Liu ; Yong Lu
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：February 6, 2017
• 年：2017
• 卷：5
• 期：2
• 页码：1840-1853
• 全文大小：883K
• ISSN：2168-0485

文摘

Free-standing stainless-steel (SS)-fiber@meso-HZSM-5 core–shell catalysts engineered from micro- to macro-scale were highly efficiently synthesized via cost-effective steam-assisted crystallization (SAC) method. Impact of synthesis conditions on their morphology and textural/acidic properties was investigated by means of XRD, SEM, TEM, solid-state NMR, NH₃-TPD, Py-IR and N₂ physisorption. Single-run lifetime of such structured catalysts for MTP process was strongly dependent on their preparation conditions but slightly the product distribution. A volcano-like relationship for lifetime was observed against the SAC time, which was correlated well with the crystallization-time-dependent crystallinity, mesoporosity and crystal size. The promising SS-fiber@meso-HZSM-5 was the one obtained after the SAC for 12 h, which delivered a prolonged single-run lifetime of 620 h with a high propylene selectivity of ∼42% at 450 °C using a methanol weight hourly space velocity (WHSV) of 1 hp>–1p>, as the result of high crystallinity, well-developed mesoporosity and small crystal size. Note that well-developed mesoporosity was paramount for the catalyst stability improvement, because of enhanced accommodation capacity of zeolite shell for receiving formed coke.