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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2017 Vol.18 No.3 P.225-233
Dual bed catalyst system for oxidative dehydrogenation of mixed-butenes: a synergistic mechanism
Abstract: Oxidative dehydrogenation (ODH) of mono and mixed-butenes to 1,3-butadiene (BD) was conducted using individual and dual bed catalyst systems, consisting of ZnFe2O4, Co9Fe3Bi1Mo12O51 or both. The dual bed catalyst system gave improved catalytic performance. A mechanism based on synergy between the catalysts is proposed to explain the improved overall butene conversion. The proportion of the reactants differed between the catalyst beds in the dual bed system, making better use of the catalytic activity of the second bed. The existence of all butene isomers inhibited isomerization, leading to a higher proportion of ODH reactions and thus improved the conversion of butene and the yield of BD. The packing sequences and the volume ratio of the catalysts in the bed were optimized. The results indicated that the sequence with ZnFe2O4 on top and a catalyst packing ratio of between 4:6 and 6:4 led to better activity.
Key words: Mixed-butenes, Dual bed catalyst, Oxidative dehydrogenation (ODH), Synergistic effect
创新点:1. 提出基于丁烯异构体在床层之间浓度重分布和异构化效应抑制作用的协同作用机理;2. 设计验证实验,从直观角度证实机理,并优化了催化剂的装填量和装填顺序。
方法:1. 通过单一丁烯和混合丁烯的氧化脱氢反应,对单一催化剂和双床层催化剂进行反应评估,得到相关反应数据;2. 通过设计对比实验,从改变参加反应物质的直观角度对协同机理进行验证和解释;3. 对参加反应的双层床催化剂中两种催化剂的装填量和装填顺序进行优化,为进一步研究组合型催化剂提供实验基础。
结论:1. ZnFe2O4对两种2-丁烯有更优的催化效果,而Co9Bi1Fe3Mo12O51对1-丁烯有更优的催化效果,由两者组成的双层床催化体系对单一丁烯和混合丁烯的反应效果都有所提升,证明两种催化剂之间存在协同效应。2. 双层床催化剂体系中,两种催化剂之间的协同作用机理是:催化剂不同活性导致丁烯异构体在床层之间的浓度发生重分布,同时由于多种异构体同时存在抑制了异构化反应。3. 对双层床催化剂体系的装填顺序和装填量的优化结果表明,ZnFe2O4装填在上层,CCo9Bi1Fe3Mo12O51装填在下层,且两者比例处于4:6到6:4之间时催化效果最佳。
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DOI:
10.1631/jzus.A1600295
CLC number:
TQ221.2
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On-line Access:
2024-08-27
Received:
2023-10-17
Revision Accepted:
2024-05-08
Crosschecked:
2017-02-22