氧化铈和铈锆固溶体对Pd催化剂抗硫性能影响的研究

Effect of CeO_2 and Ce_(0.6)Zr_(0.4)O_2 solid solution on the sulfur tolerance of Pd-based catalysts

采用等体积浸渍法制备了质量分数为1%Pd/γ-Al2O3、1%Pd/10%CeO2/γ-Al2O3以及1%Pd/10%Ce0.6Zr0.4O2/γ-Al2O3催化剂,研究了CeO2和Ce0.6Zr0.4O2固溶体对Pd催化剂抗硫性能的影响。利用XRD和XPS技术表征了催化剂的固相结构、表面元素组成和反应后催化剂中硫物种(或表面硫酸盐)的存在形态。利用SO2-TPD研究了SO2在催化剂上的吸附和脱附行为。实验结果表明,在催化剂载体中引入CeO2和Ce0.6Zr0.4O2降低了催化剂起燃活性;SO2在Pd/Ce0.6Zr0.4O2/γ-Al2O3催化剂表面上发生化学反应生成Zr(SO4)2,其热稳定性大于在Pd/γ-Al2O3和Pd/CeO2/γ-Al2O3催化剂表面上的硫酸盐或硫酸盐物种。

1% Pd/γ-Al2O3,1% Pd/10% CeO2/γ-Al2O3 and 1% Pd/10% Ce0.6Zr0.4O2/γ-Al2O3 catalysts were prepared by incipient wetness impregnation method. Effects of CeO2 and Ce0.6Zr0.4O2 solid solution on tolerance to sulfur of Pd-based catalyst were investigated. The solid structure, surface elemental composition and state of sulfur species （or surface sulfates ） in the catalysts after reaction were characterized using X-ray powder diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. adsorption/desorption of SO2 on the catalysts were studied using SO2 temperature-programmed desorption （SO2-TPD）. The results showed that doping of CeO2 and Ce0.6Zr0.4O2 lowered the combustion-initiating temperature; Zr（ SO4 ）2 formed on 1% Pd/10% Ce0.6Zr0.4O2γ-Al2O3 catalyst, whose thermal stability was higher than sulfates formed on 1% Pd/10%CeO2/γ-Al2O3 and 1% Pd/10 % Ce0.6Zr0.4O2/γ-Al2O3.