La助剂对Pd-AL2O3催化C3H8氧化性能的研究

Influence of La Promoter in Pd/AL2O3 Catalyst on C3H8 Oxidation

摘要:

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的C3H8催化氧化性能，并通过H2-TPR、XRD、XPS等手段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Pd2+物种，从而提高了催化剂的C3H8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Pd2+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。

Abstract:

Different rare earth La precursors were used to modify Pd/γ-Al2O3 catalyst via incipient wetness impregnation method. C3H8 oxidation performance was studied using powder sample evaluation device and the structures of catalysts were characterized through H2-TPR, XRD, XPS, etc. The results showed that addition of lanthanum effectively promotes palladium dispersion, strengthens Pd-support interaction and stabilizes highly-active Pd2+ species, improving the catalytic activity for C3H8 oxidation. Addition of lanthanum nitrate showed the best promoted-effect in palladium dispersion and stabilization of highly-active Pd2+ species. Compared with Pd/Al2O3, La-modified catalysts showed lower Ts, T50 and T50 values for C3H8 and NO conversion. Lanthanum addition induced changes in metal-support interaction and disperse state of active species play a significant role in enhanced activity for C3H8 catalytic oxidation.