助剂对低温水煤气变换反应Au/α-Fe_2O_3催化剂性能的影响

Effect of promoter on the performance of low-temperature water-gas shift reaction in H_2-rich steam over supported gold catalyst

采用共沉淀法制备了系列Au/α-Fe2O3-MOx(M=Zr、A l、Mg、Ca、Ba)催化剂,通过N2物理吸附、XRD、H2-TPR和CO2-TPD-MS等手段对催化剂的物化性质进行表征,考察了富氢下低温水煤气变换(WGS)反应中助剂对Au/α-Fe2O3催化剂性能的影响。结果表明,助剂ZrO2能有效提高Au/α-Fe2O3催化剂在富氢气氛下低温WGS反应活性和稳定性,反应温度150℃时CO转化率可达88.45%,且催化剂具有较高的稳定性。研究发现,添加ZrO2助剂能抑制载体晶粒的生长,降低载体晶粒度,提高催化剂的比表面积,改善催化剂的还原性能和表面酸碱度,从而提高催化剂的催化活性和稳定性。

The Au/α-Fe2O3 -MOx catalysts （ M = Zr , Al, Mg, Ca, Ba） prepared by coprecipitation method were characterized by BET , XRD, H2-TPR and CO2-TPD-MS. The catalytic performance for low-temperature watergas shift reaction（WGSR） in H2-rich gas was investigated. It was found that the activity and stability of Au/α- Fe2O3-MOx was strongly dependent on the type of additive. Among the tested samples, the Au/α-Fe2O3 catalyst modified by ZrO2 or Al2O3 showed highest activity and stability. On the contrary, the modification by MgO ,CaO and BaO resulted in an activity decrease. The structure and surface analyses revealed that zirconia added to the the Au/α-Fe2O3 catalyst increased the surface area, decreased crystallite size of support, and limited the growth of the crystallite size of support during the catalytic reaction. The results indicated that addition of the promoter zirconia and alumina, changed the structure and performances of the support and resulted in higher activity and stability.