Effect of Citric Acid on the Synthesis of CO Methanation Catalysts with High Activity and Excellent Stability

Abstract

Several Ni-based SBA-16 catalysts were synthesized by a citric acid (CA)-assisted impregnation method and applied for syngas methanation in a fix-bed reactor. Various characterization techniques (N2 physical adsorption, powder X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and ultraviolet–visible spectroscopy) were used to characterize the catalysts. The amount of citric acid has significant influence on the properties of the catalysts. A small amount of CA could improve the dispersion of nickel species and refine the particle size of the catalysts. The refined nickel particles (3–5 nm) could anchor into the pores (6–7 nm) of the silica, which leads to the confinement of nickel particles. The best activity was obtained on Ni/SBA-16–15%CA catalysts with 100% CO conversion and 99.9% CH4 selectivity at 350 °C, 0.1 MPa, and 15 000 mL/g/h. The catalysts prepared with CA exh...