Controllable synthesis of Ir(Rh)–Sn/SiO2 bimetallic catalysts via surface organometallic chemistry for the production of ethanol from hydrogenolysis of ethyl acetate
Controllable synthesis of Ir(Rh)–Sn/SiO2 bimetallic catalysts via surface organometallic chemistry for the production of ethanol from hydrogenolysis of ethyl acetate
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DOI：
10.1039/c9cy02071c
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发表时间：
2020-02
影响因子：
5
通讯作者：
Rui Xu;Kunbo Lian;Zhikang Xu;Yuanyuan Yue;Pei Yuan;Xiaojun Bao;Xiaohong Yuan;Haibo Zhu
中科院分区：
文献类型：
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作者：
Rui Xu;Kunbo Lian;Zhikang Xu;Yuanyuan Yue;Pei Yuan;Xiaojun Bao;Xiaohong Yuan;Haibo Zhu
乙醇作为传统化石燃料的替代品，近来在世界范围内备受关注，因为乙醇被证明是一种清洁、绿色、高效的燃料。通过酯的催化氢解间接合成气制备乙醇已成为最具竞争力和可持续发展的路线之一。Ir-Sn和Rh-Sn双金属材料是该反应最有效的催化剂，因为它们在长期反应中表现出高的活性、选择性和稳定性。基于表面有机金属化学的概念，通过在SiO2表面直接生成Ir（Rh）-Sn纳米粒子，发展了一种合成Ir（Rh）-Sn/SiO2催化剂的接枝方法。SiO_2表面的SiO_2颗粒的形成是通过在脱羟基SiO_2表面依次接枝[（COD）IrCl]_2（或Rh（acac）（COD））和HSnBu_3复合物得到的SiOIr（COD）/SiOSnBu_3或SiORh（COD）/SiOSnBu_3的氢解而实现的。这种分子合成方法能够在温和条件下在SiO2表面原位生成Ir-Sn或Rh-Sn簇，并提供高度分散的Ir-Sn/SiO2和Rh-Sn/SiO2催化剂。采用STEM、XRD、N2吸附、CO-IR和XPS等技术对这两种催化剂的结构进行了系统研究，结果表明，Ir-Sn和Rh-Sn颗粒均匀分布在SiO2表面，粒径约为1.2 nm。Sn/Ir（Rh）比为1的Ir-Sn/SiO2和Rh-Sn/SiO2催化剂在乙酸乙酯氢解制备乙醇的反应中表现出最好的性能，其可以提供高达99%的乙醇选择性。此外，这两种催化剂在催化反应中表现出优异的稳定性，其高转化率和选择性可以完全保持120小时的长期运行。
Ethanol as an alternative to traditional fossil fuels has recently attracted much attention all over the world, because ethanol is proven to be a clean, green and efficient fuel. Ethanol production from indirect syngas synthesis via the catalytic hydrogenolysis of esters has become one of the most competitive and sustainable routes. Ir–Sn and Rh–Sn bimetallic materials constitute the most effective catalysts for this reaction, because they exhibit high activity, selectivity and stability in the long-term reaction. A grafting approach based on the surface organometallic chemistry concept is developed for the synthesis of Ir(Rh)–Sn/SiO2 catalysts via the direct generation of Ir(Rh)–Sn bimetallic particles at the surface of SiO2. The formation of bimetallic particles at the surface of SiO2 was achieved by hydrogenolysis of the well-defined surface compounds SiOIr(COD)/SiOSnBu3 or SiORh(COD)/SiOSnBu3, which were obtained from sequential grafting of [(COD)IrCl]2 (or Rh(acac)(COD)) and HSnBu3 complexes at the surface of dehydroxylated SiO2. This molecular synthesis methodology enables in situ generation of Ir–Sn or Rh–Sn clusters at the surface of SiO2 under mild conditions, and affords highly dispersed Ir–Sn/SiO2 and Rh–Sn/SiO2 catalysts. The detailed structure of these two catalysts was systematically studied by STEM, XRD, N2 adsorption, CO-IR and XPS techniques, which reveal that the Ir–Sn and Rh–Sn particles of around 1.2 nm are homogeneously distributed at the surface of the SiO2. The Ir–Sn/SiO2 and Rh–Sn/SiO2 catalysts with a Sn/Ir(Rh) ratio of 1 show the best performance in the hydrogenolysis of ethyl acetate for the production of ethanol, which can deliver a selectivity to ethanol of up to 99%. Moreover, these two catalysts show excellent stability in the catalytic reaction, and their high conversion and selectivity can be completely kept for a long-term run of 120 hours.