Bimetallic Ni-Zn site anchored in siliceous zeolite framework for synergistically boosting propane dehydrogenation
Bimetallic Ni-Zn site anchored in siliceous zeolite framework for synergistically boosting propane dehydrogenation
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DOI：
10.1016/j.fuel.2021.121790
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发表时间：
2022
期刊：
影响因子：
7.4
通讯作者：
Chengming Huang;D. Han;Linjie Guan;Linhua Zhu;Yi Mei;Dedong He;Yun Zu
中科院分区：
文献类型：
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作者：
Chengming Huang;D. Han;Linjie Guan;Linhua Zhu;Yi Mei;Dedong He;Yun Zu
丙烷脱氢（PDH）是一种很有前景的生产丙烯的良性工艺，但通常依赖于高价Pt和有毒的Cr（VI）催化剂，这些催化剂经常受到金属烧结和严重焦炭沉积引起的快速失活的影响。为了克服这些问题，高效、低成本和环保的替代催化剂设计的突破对成功开发这一过程起着至关重要的作用。本文采用配体保护策略，制备了锚定在硅石-1分子筛骨架上的Ni-Zn双金属位催化剂（描述为NiZn-S-1），具有高温稳定性。在相同条件下，高Ni/Zn摩尔比为3:1的NiZn-S-1催化剂（命名为0.2Ni0.06Zn-S-1）表现出优异的催化活性（初始丙烷转化率为32.5%，实际tof丙烷转化率为28.5 min−1）、低失活率（0.0778 h−1）和高丙烯选择性（>90%）。特别是在连续4次氧化还原循环后，该催化剂的催化性能与新鲜催化剂基本保持一致。多重表征进一步表明，PDH性能的增强应归因于双金属Ni-Zn位点之间的协同作用，有利于C-H键的选择性活化和丙烯的脱附，减少高石墨化程度焦炭的形成，促进催化剂稳定性的提高。新型双金属位催化剂的设计为今后开发经济环保的PDH催化剂提供了新的思路。
Propane dehydrogenation (PDH) is a prospective benign process for the production of propylene, but generally depends on high-price Pt and toxic Cr(VI) catalysts that often suffer from the rapid deactivation derived from metal sintering and severe coke deposition. To overcome these problems, the breakthroughs in an alternative catalyst design with efficient, low-cost and eco-friendly play a crucial role in successfully developing this process. Here, we facilely fabricate the bimetallic-site catalyst of Ni-Zn anchored in the zeolitic framework of silicalite-1 (depicted as NiZn-S-1) by employing ligand-protected strategy, which performs high temperature stability. Under comparable conditions, the NiZn-S-1 catalyst with high Ni/Zn molar ratio of 3:1 (named 0.2Ni0.06Zn-S-1) exhibits superior catalytic activity (initial propane conversion of 32.5 % and actual TOFpropaneof 28.5 min−1) with low deactivation rate (0.0778 h−1) and great propylene selectivity (>90%) after 30 h on stream. In particular, the catalytic performance on this catalyst almost keeps same as that of fresh catalyst after 4 successive oxidation–reduction cycles. Multiple characterizations further demonstrate that the enhancement of PDH performance ought to be attributed to the synergistic effect between bimetallic Ni-Zn sites, which favors the selective activation of C–H bond and propylene desorption to reduce the formation of coke species with high graphitization degree, boosting the improvement of catalyst stability. The design of novel bimetallic-sites catalyst can give a new idea on the development of alternative PDH catalysts with economical- and environment-friendly in the future.