Isovalent substituted La-Gd-Cr perovskite for the cleaner hydrogen production during partial oxidation methane in catalytic packed bed

Abstract

Perovskite as a catalytic material with high activity and thermal stability effectively improved methane conversion efficiency and hydrogen yield. To combine the advantages of catalyst and porous media, La1-xGdxCrO3 (x = 0, 0.2, 0.5 and 0.8) perovskite catalysts were prepared by sol-gel method and loaded on Al2O3 pellet supports to build a catalytic pellet packed bed. And the effects of A-site isovalent doping on the catalytic activity and combustion characteristics of catalytic pellets were studied. The results demonstrated that with the increasing of Gd doping, the crystal structure changed from cubic to orthorhombic and the content of Cr6+ increased to 29.53 %. The A-site partial doping improved the combustion temperature and the hydrogen yield reached the maximum at Gd = 0.2. When pellet diameter increased to 8 mm, the catalytic combustion effect of La0.8Gd0.2CrO3 was enhanced. Meanwhile, compared with La0.2Gd0.8CrO3, the La0.8Gd0.2CrO3 showed better catalytic activity and obtained the maximum CH4 conversion of 93.90 % at the inlet velocity of 12 cm/s and equivalence ratio of 1.5. The combination of A-site optimized perovskite and porous media greatly promoted the partial oxidation of methane and enhanced the hydrogen production efficiency.