化工进展 ›› 2020, Vol. 39 ›› Issue (2): 567-576.DOI: 10.16085/j.issn.1000-6613.2019-0544

• 工业催化 • 上一篇    下一篇

CuZnTiO2/SAPO-34双功能催化剂的设计、制备及其用于CO2加氢制烯烃性能

陈静宇(),张建红,盛浩,吴大凯,高新华(),马清祥,张建利(),范素兵,赵天生   

  1. 省部共建煤炭高效利用与绿色化工国家重点实验室(宁夏大学),宁夏 银川 750021
  • 收稿日期:2019-04-09 出版日期:2020-02-05 发布日期:2020-03-12
  • 通讯作者: 高新华,张建利
  • 作者简介:陈静宇(1993—),女,硕士研究生,研究方向为煤基应用催化。E-mail:852858917@qq.com
  • 基金资助:
    国家自然科学基金(21666030);宁夏重点研发计划(2018BEE03010);宁夏自然科学基金(2018AAC02002);宁夏大学研究生创新项目(GIP2018035)

Design and preparation of CuZnTiO2/SAPO-34 bifunctional catalyst and its catalytic performance in CO2 hydrogenation to light olefins

Jingyu CHEN(),Jianhong ZHANG,Hao SHENG,Dakai WU,Xinhua GAO(),Qingxiang MA,Jianli ZHANG(),Subing FAN,Tiansheng ZHAO   

  1. State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, Ningxia, China
  • Received:2019-04-09 Online:2020-02-05 Published:2020-03-12
  • Contact: Xinhua GAO,Jianli ZHANG

摘要:

CO2加氢经甲醇(含氧中间体)制低碳烯烃工艺路线,可实现成醇、脱水两步反应串联协同进行,打破费托合成产物Anderson-Schulz-Flory(ASF)分布限制,高选择性地制取低碳烯烃。传统甲醇合成Cu基催化剂加氢能力较强,在两步反应中产物以CH4、低碳烷烃为主。实验设计、制备了CuZnTiO2/(Zn-)SAPO-34复合催化剂,实现了CO2加氢在Cu基复合催化剂上高选择性合成C2~C4烯烃(约60%)。研究表明,两步反应过程中甲醇体积分数较低(<6%),且高温下逆水煤气变换反应严重,导致催化剂酸性变化对产物分布的影响较大。调变两类活性位点比例发现,CH4的产生与串联反应存在竞争关系,SAPO-34酸量的增加抑制了CH4的生成,促进串联反应正向进行;合适的酸性有助于生成C2~C4烯烃。控制成醇、脱水两类活性位点接触距离可调变烯烃的二次反应,降低加氢能力,改善产物分布。

关键词: 二氧化碳, 加氢, 分子筛, 低碳烯烃, 接触距离

Abstract:

CO2 hydrogenation to light olefins bymethanol synthesis or oxide intermediates, is accomplished through two successive reactions of activation of CO2 to methanol and methanol conversion to olefins. This route can break the product distribution limitation of Anderson-Schulz-Flory (ASF) via Fischer-Tropsch synthesis and produce light olefins with high selectivity. It is reported that the products from traditional Cu-based composite catalysts mainly include methane and alkanes due to their strong hydrogenation ability during CO2 hydrogenation. Herein, we report the design and preparation of CuZnTiO2/(Zn-)SAPO-34 composite catalyst that shows high selectivity for C2—C4 olefins (around 60%). The study demonstrates that the acidity of the catalyst has great influence on product distribution, due to the low methanol concentration (<6%) and high activity of the reverse water gas shift reaction (RWGS) at high temperature during the two-step reaction process. There exists competition between the formation of methane and the tandem reaction with the change of the content of two active components. The increase of the acid content of SAPO-34 can inhibit the formation of methane and promote the tandem reaction. Reduction in acidity of SAPO-34 by Zn promotion also contributes to the formation of light olefins. It is favorable to suppress the secondary hydrogenation reaction of light olefins, by controlling the distance between the two active components.

Key words: carbon dioxide, hydrogenation, molecular sieves, light olefins, contact distance

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