SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2022, Vol. 46 ›› Issue (6): 173-183.DOI: 10.1016/j.cjche.2021.05.041

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Comparative catalytic study on butene/isobutane alkylation over LaX and CeX zeolites: The influence of calcination atmosphere

Zhiqiang Yang1,2, Ruirui Zhang2, Honghua Zhang2, Hongguo Tang2, Ruixia Liu2,3, Suojiang Zhang1,2,3   

  1. 1 School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, China;
    2 Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, 100049 Beijing, China;
    3 School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-02-18 Revised:2021-04-15 Online:2022-07-20 Published:2022-06-28
  • Contact: Ruixia Liu,E-mail:rxliu@ipe.ac.cn;Suojiang Zhang,E-mail:sjzhang@ipe.ac.cn
  • Supported by:
    This work was supported by the National Key Research and Development Program of China (2017YFA0206803), the National Natural Science Foundation of China (21878315), the Key Programs of the Chinese Academy of Sciences (KFZD-SW-413), the Key Programs of Innovation Academy for Green Manufacture, CAS (IAGM2020C17), K. C. Wong Education Foundation (No. GJTD-2018-04), and the Major Program of National Natural Science Foundation of China (21890762).

Comparative catalytic study on butene/isobutane alkylation over LaX and CeX zeolites: The influence of calcination atmosphere

Zhiqiang Yang1,2, Ruirui Zhang2, Honghua Zhang2, Hongguo Tang2, Ruixia Liu2,3, Suojiang Zhang1,2,3   

  1. 1 School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, China;
    2 Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, 100049 Beijing, China;
    3 School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
  • 通讯作者: Ruixia Liu,E-mail:rxliu@ipe.ac.cn;Suojiang Zhang,E-mail:sjzhang@ipe.ac.cn
  • 基金资助:
    This work was supported by the National Key Research and Development Program of China (2017YFA0206803), the National Natural Science Foundation of China (21878315), the Key Programs of the Chinese Academy of Sciences (KFZD-SW-413), the Key Programs of Innovation Academy for Green Manufacture, CAS (IAGM2020C17), K. C. Wong Education Foundation (No. GJTD-2018-04), and the Major Program of National Natural Science Foundation of China (21890762).

Abstract: Lanthanum-containing (LaX) and cerium-containing X zeolites (CeX) were prepared by a double-exchange, double-calcination method. By changing the calcination atmospheres between nitrogen and air, the CeIV contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established. The crystallinity of CeX zeolite was found to be negatively correlated with the CeIV content. This i s believed to be due to the water formed during the oxidation of CeIII, which facilitates the framework dealumination. As a consequence, calcining in air resulted in a great elimination of strong Brønsted acid sites while under nitrogen protection, this phenomenon was mostly hindered and the sample's acidity was preserved. When tested in a continuously flowed slurry reactor, the catalyst lifetime for isobutane alkylation was found to be linearly related to the strong Brønsted acid concentration. In addition, Ce3+ was found more benefit for the hydride transfer compared with La3+, which is ascribed to the stronger polarization effect on the CH bond of isobutane. Moreover, the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules. Based on the product distribution, a new catalytic cycle of dimethylhexanes (DMHs) involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.

Key words: CeX zeolite, Calcination atmosphere, Isobutane alkylation, Brønsted acid, Hydride transfer

摘要: Lanthanum-containing (LaX) and cerium-containing X zeolites (CeX) were prepared by a double-exchange, double-calcination method. By changing the calcination atmospheres between nitrogen and air, the CeIV contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established. The crystallinity of CeX zeolite was found to be negatively correlated with the CeIV content. This i s believed to be due to the water formed during the oxidation of CeIII, which facilitates the framework dealumination. As a consequence, calcining in air resulted in a great elimination of strong Brønsted acid sites while under nitrogen protection, this phenomenon was mostly hindered and the sample's acidity was preserved. When tested in a continuously flowed slurry reactor, the catalyst lifetime for isobutane alkylation was found to be linearly related to the strong Brønsted acid concentration. In addition, Ce3+ was found more benefit for the hydride transfer compared with La3+, which is ascribed to the stronger polarization effect on the CH bond of isobutane. Moreover, the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules. Based on the product distribution, a new catalytic cycle of dimethylhexanes (DMHs) involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.

关键词: CeX zeolite, Calcination atmosphere, Isobutane alkylation, Brønsted acid, Hydride transfer