酸改性CoPd/TiO2催化CH4-CO2直接合成C2含氧化合物

Direct synthesis of C2-oxygenates from CH4 and CO2 over acid-modified CoPd/TiO2 catalyst

采用酸处理方法对CoPd/TiO2催化剂进行改性,并将酸改性催化剂用于温和条件下CH4-CO2梯阶转化直接合成C2含氧化合物(乙酸和乙醇)的反应。在150~300℃考察了浸酸方式和不同种类酸处理对催化剂活性和选择性的影响。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、NH3程序升温脱附(NH3-TPD)和N2吸附对催化剂进行了表征。结果表明,酸改性明显提高了CoPd/TiO2上C2含氧化合物的生成速率和选择性。浸酸方式对催化剂性能和结构有显著影响,先用酸浸渍载体然后再浸渍活性金属所得催化剂具有更高的活性。在H3PO4、HNO3和HCl中,H3PO4浸渍的催化剂活性最佳,在150℃时C2含氧化合物(乙酸和乙醇)的生成速率为3365μg/(g·h),选择性达到91%。

CoPd/TiO2 catalysts modified by acids were used to catalyze the step-wise reaction of CH4 and CO2 to directly synthesize C2-oxygenates(acetic acid and ethanol) under mildness conditions. The effect of the different introducing manners of acid and treatment of different acids on the activity and selectivity of catalysts was investigated at temperature between 150℃ and 300℃. All Catalysts were characterized by XRD, TPD, XPS, NH3-TPD and N2 adsorption. The formation rate and selectivity of C2-oxygenates was markedly improved by acid modification. The performance and structure of catalysts were obviously affected by introducing manner of acid. High activity was observed on the catalyst which was prepared by first treating the TiO2 support with acids then immobilizing Co and Pd. In the case of the treatment of H3 PO4, HNO3 and HCl, the best activity was attained on the catalyst modified by H3 PO4. The highest formation rate of C2-oxygenates(acetic acid and ethanol) reached 3365μg/(g·h), while the highest selectivity of C2-oxygenates was 91% at 150℃.