摘要
采用柠檬酸络合法制备 LaNixFe1-xO3(x 分别为 0.33、0.5、0.66)和 La1-yCeyNi0.66Fe0.33O3(y 分别为 0.1、0.2、0.3、0.4)系列钙钛矿催化剂.利用X射线衍射(XRD)、扫描电镜(SEM)、N2物理吸附对催化剂的基本性质进行表征,通过固定床实验装置进行模拟煤气催化实验和荒煤气原位催化实验.催化剂的B位Ni和Fe主要起催化作用,A位的La和Ce主要起稳定晶体结构的作用.结果表明,系列催化剂均可形成稳定的钙钛矿结构,B位Ni质量分数的提高有助于提升CO的转化率和催化剂的积碳速率,并同时降低了催化剂的比表面积和孔体积.A位掺杂Ce能够增加催化剂的晶氧空位,改变催化剂的晶体结构,提高催化剂的比表面积、孔体积、抗硫性能和抗积碳性能.对比原位催化减水效果发现,LaNixFe1-xO3系列催化剂中LaNi0.66Fe0.33O3的减水效果较好,热解水产率下降了 35％;La1-yCeyNi0.66Fe0.33O3系列催化剂中La0.7Ce0.3Ni0.66Fe0.33O的减水效果最好,热解水产率下降了 40％.
Abstract
LaNixFe1-xO3(x=0.33,0.5,and 0.66,respectively)and La1-y).CeyNi0.66Fe0.33O3(y=0.1,0.2,0.3,and 0.4,respectively)perovskite catalysts are prepared through using the citric acid complexation method,and characterized by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),and N2 physical adsorption.Their catalytic performance is evaluated through catalytic test of simulated coal gas and in situ catalytic test of raw coal gas in a fixed-bed experimental reactor.It is found that Ni and Fe species at B-site of the catalysts primarily play catalytic roles,while La and Ce ions at A-site of the catalysts mainly play a role in stabilizing the crystal structure.The results show that each of the catalysts forms a stable perovskite structure.The higher Ni content at B-site is helpful to improve the CO conversion rate,but leads to higher carbon deposition rate,lower specific surface area and pore volume of the catalysts.Ce doping at A-site can increase the concentration of oxygen vacancy and alter the crystal structure,resulting in higher specific surface area,pore volume,sulfur resistance and carbon resistance.It is found through comparing in situ water reduction effect that LaNi0.66Fe0.33O3 in LaNixFe1-xO3 series shows the best catalytic performance for in situ water-gas shift reaction,with a 35％reduction in the water-gas shift rate.Among La1-yCeyNi0.66Fe0.33 O3 series,La0.7Ce0.3Ni0.66Fe0.33O exhibits the best performance,with a 40％reduction in the water-gas shift rate.
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