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    铜基催化剂载体组成(MZr4O2)对CO2加氢制甲醇活性影响

    Influence of support composition (MZr4O2) of Cu−based catalysts on activity in CO2 hydrogenation to methanol

    • 摘要: 二氧化碳加氢制甲醇,不仅能够实现碳排放的控制,还可以减少化石能源的消耗,是实现CO2资源化利用的有效途径之一。铜基催化剂在高温、高压下能够催化CO2加氢转化为甲醇,但传统铜基催化剂存在CO2活化能力弱、目标产物甲醇选择性低、氧化物负载的活性铜物种稳定性差等问题,因此高效、稳定的新型铜基催化剂开发是CO2加氢合成甲醇反应中的重要研究内容。基于此,制备了4种不同的锆基双金属氧化物为载体的铜基催化剂,分别为Cu/TiZr4O2、Cu/ZnZr4O2、Cu/GaZr4O2和Cu/CeZr4O2,并进行了CO2加氢合成甲醇试验。结果表明:以TiZr4O2氧化物为载体的Cu/TiZr4O2催化剂具有良好的催化活性。表征分析表明,H2还原后的Cu/TiZr4O2催化剂表面具有大量的不饱和Cu物种(Cu0),与丰富的氧空位和表面碱性位点相结合,促进了CO2和H2的吸附和活化。较小的Cu粒径、较大的Cu比表面积和分散度共同促进了H2的活化。优异的物理化学性质使得Cu/TiZr4O2催化剂表现出良好的催化活性。此外,反应机理结果表明甲酸盐物种是Cu/TiZr4O2催化剂催化CO2加氢合成甲醇的关键中间体。

       

      Abstract: Hydrogenation of carbon dioxide to methanol can not only achieve the control of carbon emission, but also reduce the consumption of fossil energy, which is one of the effective ways to realize the utilization of CO2 resources. Copper-based catalysts are capable of catalyzing the conversion of CO2 hydrogenation to methanol at high temperature and high pressure, but the traditional copper-based catalysts suffer from the problems of weak CO2 activation ability, low selectivity of methanol as the target product, and poor stability of oxide-loaded activated copper species, and so on. Therefore, the development of highly efficient, stable and novel copper-based catalysts is an important part of the research in the reaction of methanol synthesis by CO2 hydrogenation. In this study, four copper-based catalysts supported by zirconium bimetallic oxides, namely Cu/TiZr4O2, Cu/ZnZr4O2, Cu/GaZr4O2, and Cu/CeZr4O2, are synthesized and tested in CO2 hydrogenation experiments for methanol production. The results show that the Cu/TiZr4O2 catalysts with TiZr4O2 oxides as carriers have good catalytic activity. Characterization analyses show that the H2 reduced Cu/TiZr4O2 catalysts have a large number of unsaturated Cu species (Cu0) on the surface, which combined with abundant oxygen vacancies and surface alkaline sites to promote the adsorption and activation of CO2 and H2. The smaller Cu particle size, larger Cu specific surface area and dispersion combined to promote H2 activation. The excellent physicochemical properties enable the Cu/TiZr4O2 catalyst to exhibit good catalytic activity. In addition the reaction mechanism suggests that formate species are key intermediates in the synthesis of methanol from CO2 hydrogenation catalyzed by Cu/TiZr4O2 catalysts.

       

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