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<p>Efficient ammonia synthesis is a significant but challenging target. One of questions faced by Ru-based ammonia synthesis catalyst is the hydrogen poisoning of Ru. In this work, we developed a strategy to greatly alleviate the effect by regulating hydrogen acceptance capacity of support MgO, thereby promoting the ammonia synthesis rate. To this end, three kinds of MgO (i.e., MgO nanocube (MgO-c), MgO nanoplate (MgO-p) and MgO nanosphere (MgO-s)) were chosen as the support of Ru catalysts for ammonia synthesis. The ammonia synthesis rate of 4Cs–Ru/MgO-c is 4466&#xa0;μmol&#xa0;g<sup>−1</sup><sub>cat</sub> h<sup>−1</sup>, higher than the 2Cs–Ru/MgO-p (3483&#xa0;μmol&#xa0;g<sup>−1</sup><sub>cat</sub> h<sup>−1</sup>) and Cs–Ru/MgO-s (2080&#xa0;μmol&#xa0;g<sup>−1</sup><sub>cat</sub> h<sup>−1</sup>) at 350&#xa0;℃ and 0.1&#xa0;MPa. The kinetic analysis results show that the value of the hydrogen reaction order is 4Cs–Ru/MgO-c &gt; 2Cs–Ru/MgO-p &gt; Cs–Ru/MgO-s &gt; 0, indicating that no hydrogen poisoning occurs. The H<sub>2</sub>-TPR and in situ FTIR characterizations show that MgO-c support has more active sites which can accept hydrogen atoms from the Ru surface as compared to the other two kinds of MgO. Meanwhile, the active sites released from the Ru surface can be used for N<sub>2</sub> activation, which will reduce the reaction activation energy of ammonia synthesis. Therefore, MgO containing abundant active sites for accepting hydrogen atoms can be expected to be a promising commercial catalyst support for Ru-based ammonia synthesis.</p>

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Regulation of hydrogen acceptance capacity of MgO to enhance ammonia synthesis rate of Cs–Ru/MgO by hydrogen spillover

  • 期刊论文

  • 发表日期：

    2025年7月18日

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  • Chao Gao,
  • Jia Huang,
  • Peng Zhang,
  • Xiancan Jiang,
  • Zhixiong You

摘要

Efficient ammonia synthesis is a significant but challenging target. One of questions faced by Ru-based ammonia synthesis catalyst is the hydrogen poisoning of Ru. In this work, we developed a strategy to greatly alleviate the effect by regulating hydrogen acceptance capacity of support MgO, thereby promoting the ammonia synthesis rate. To this end, three kinds of MgO (i.e., MgO nanocube (MgO-c), MgO nanoplate (MgO-p) and MgO nanosphere (MgO-s)) were chosen as the support of Ru catalysts for ammonia synthesis. The ammonia synthesis rate of 4Cs–Ru/MgO-c is 4466 μmol g−1cat h−1, higher than the 2Cs–Ru/MgO-p (3483 μmol g−1cat h−1) and Cs–Ru/MgO-s (2080 μmol g−1cat h−1) at 350 ℃ and 0.1 MPa. The kinetic analysis results show that the value of the hydrogen reaction order is 4Cs–Ru/MgO-c > 2Cs–Ru/MgO-p > Cs–Ru/MgO-s > 0, indicating that no hydrogen poisoning occurs. The H2-TPR and in situ FTIR characterizations show that MgO-c support has more active sites which can accept hydrogen atoms from the Ru surface as compared to the other two kinds of MgO. Meanwhile, the active sites released from the Ru surface can be used for N2 activation, which will reduce the reaction activation energy of ammonia synthesis. Therefore, MgO containing abundant active sites for accepting hydrogen atoms can be expected to be a promising commercial catalyst support for Ru-based ammonia synthesis.