Perovskite LaNiO3 Nanocrystals inside Mesostructured Cellular Foam Silica: High Catalytic Activity and Stability for CO2 Methanation

摘要

To simultaneously obtain high catalytic activity and stability, LaNiO3-based catalysts supported on mesostructured cellular foam (MCF) silica are prepared by a citric acid-assisted impregnation method and applied for a CO2 methanation reaction. These MCF-supported perovskite LaNiO3 (LaNiO3/MCF) samples are characterized by nitrogen adsorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, H-2-temperature-programmed reduction, and X-ray photoelectron spectroscopy. The results indicate that these catalysts offer highly dispersed La2O3 and metallic Ni nanoparticles with intimate contact inside the pores of MCF support after reduction in H-2 flow. Compared with the catalyst prepared by the coimpregnation method (30LNOM-Im-650), the citric acid-assisted LaNiO3/MCF (30LNOM-C-650) catalyst exhibits a much higher catalytic activity due to its higher Ni dispersion and stronger interrelationship between La2O3 and Ni species. In the 100 h-lifetime test under the conditions of 450 degrees C, 0.1 MPa, and a high weight hourly space velocity of 60 000 mL g(-1) h(-1), 30LNOM-C-650 also shows a high long-term stability without Ni sintering, which is attributed to the formation of enhanced interaction between metallic Ni and La2O3 via La2O2CO3 species on their interface as well as the confinement effect of the MCF support.