合成气制乙醇RhCu双金属催化剂活性位点的作用机制研究

Study on the effect of active sites of ethanol synthesis from syngas over RhCu bimetallic catalyst

  • 摘要: 稳定高效双金属催化剂的研究对于合成气直接合成乙醇具有重大意义,但也存在一定的挑战。本研究采用尿素辅助凝胶法和初湿浸渍法,制备了系列RhCu/P25双金属催化剂,并进行合成气直接制乙醇性能研究。研究表明,Rh改性的Cu基催化剂可以有效促进乙醇的生成,然而Rh和Cu活性位点之间紧密接触时,反应产物以甲烷和甲醇为主,乙醇含量甚微。RhCu/P25双金属催化剂反应性能的减弱与Rh和Cu活性位点上CO分子吸附受到抑制相关。当采用物理混合的方式增大Rh和Cu活性位点的空间距离时,CO分子的吸附明显增强,催化活性以及乙醇选择性提高。

     

    Abstract: Developing efficient and stable bimetallic catalysts has been a highly promising challenge for the direct synthesis of ethanol from syngas in recent years. In this study, a series of RhCu/P25 bimetallic catalysts with different Rh contents were prepared by combining the urea-assisted gel method and the impregnation method, and their performance in ethanol synthesis from syngas was studied. The results show that Rh-modified Cu-based catalyst can effectively promote the ethanol production. However, when the active sites of Rh and Cu are in close contact, the reaction products are mainly methane and methanol, and ethanol content is very low. This should be attributed to the inhibition of the adsorption of CO molecules on the Rh and Cu active sites. When the spatial distance between the Rh and Cu active sites is increased by physical mixing, the adsorption of CO molecules is significantly enhanced, and the catalytic activity and ethanol selectivity are improved.

     

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