La助剂对Pd/γ-Al2O3催化C3H8氧化性能的影响

Influence of La Promoter in Pd/Al2O3 Catalyst on C3H8 Oxidation

采用不同稀土La前驱体浸渍掺杂改性Pd/γ-Al2O3催化剂,利用多功能催化性能评价装置测试不同催化剂对C3H8的催化氧化性能,并通过H2-TPR、XRD、XPS等对催化材料进行结构表征。结果表明:La能促进贵金属钯分散,增强钯与载体相互作用,稳定高活性Pd^2+物种,从而提高了催化剂对C3H8的催化氧化性能。在选用不同La前驱体改性的Pd/γ-Al2O3催化剂中,硝酸镧改性效果最佳,能更好地促进活性金属钯的分散和Pd^2+高活性物种的稳定。相比Pd/γ-Al2O3,La改性催化剂均降低了C3H8和NO的反应转化温度。选用不同La前驱体对催化活性影响存在差异的主要原因是La前驱体添加而引起的金属-载体相互作用和活性贵金属钯的分散状态变化。

Different rare earth La precursors were used to modify Pd/γ-Al2O3 catalyst via an incipient wetness impregnation method.C3H8oxidation performance was studied using a powder sample evaluation device and the structures of catalysts were characterized through H2-TPR,XRD,XPS,etc.The results show that addition of lanthanum effectively promotes palladium dispersion,strengthens Pd-support interaction and stabilizes highly-active Pd^2+species,thus improving the catalytic activity for C3H8 oxidation.Addition of lanthanum nitrate shows the best promoting-effect in palladium dispersion and stabilization of highly-active Pd^2+species.Compared with Pd/γ-Al2O3,La-modified catalysts show lower Ts,T50 and T90 values for C3H8 and NO conversion.Lanthanum addition induces changes in metal-support interaction and dispersive state of active species,which plays a significant role in enhancing activity for C3H8 catalytic oxidation.