Lewis酸碱调控镧掺杂氧化锌催化CO2转化制碳酸乙烯酯

Lewis acid-base modulated lanthanum-doped zinc oxide catalyzed CO2 conversion to ethylene carbonate

  • 摘要: 本研究以CO2和乙二醇(EG)合成碳酸乙烯酯(EC)为目标,设计合成一系列La掺杂ZnO催化剂,可对ZnO表面Lewis酸碱性位点调控,并在无助剂条件下研究了催化剂活性。La-ZnO-1%-550℃具有最好的催化活性,在130 ℃、4 MPa CO2、1 h条件下,EG的转化率为0.54%,EC的时空收率和选择性分别为7.326 mmol/(h∙g)和99%,并具有良好的稳定性。结合对催化剂的晶体结构、形貌和表面酸碱性等分析,结果显示,La均匀分布在ZnO中空纳米片中,经过550 ℃煅烧的La掺杂ZnO的表面具有最多的Lewis酸碱性位点,催化剂的催化活性随中强Lewis酸碱性位点增多而升高。

     

    Abstract: The massive emission of the greenhouse gas CO2 has caused problems such as global warming and ecological damage. How to effectively utilize CO2 as a resource and create economic benefits has attracted much attention in recent years. In this paper, a series of La-doped ZnO catalysts were designed and synthesized targeting the synthesis of ethylene carbonate (EC) from CO2 and ethylene glycol (EG), which could modulate the Lewis acid-base sites on the ZnO surface, and the catalyst activity was investigated under additive-free conditions. La-ZnO-1%-550℃ had the best catalytic activity with 0.54% conversion of EG, 7.326 mmol/(h∙g) and 99% space-time yield and selectivity of EC at 130 ℃, 4 MPa CO2, and 1 h with good stability. Combined with the analysis of the crystal structure, morphology and surface acid-base of the catalysts, the results showed that La was uniformly distributed in the ZnO hollow nanosheets, and the surface of the La-doped ZnO calcined at 550 ℃ had the most Lewis acid-base sites, and the catalytic activity of the catalysts increased with the increase of moderate to strong Lewis acid-base sites.

     

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