CO methanation over highly active and coke-resistant ruthenium-doped fibrous mordenite zeolite catalyst for synthetic natural gas (SNG) production

Synthetic natural gas, or SNG, can be used as a low-carbon substitute for fossil fuels such as coal, gasoline, and natural gas. SNG can be produced by methanation of CO using an appropriate and efficient catalyst. In this study, a ruthenium-doped fibrous silica-mordenite (Ru-FSMOR) catalyst was prepared by a microemulsion method for CO methanation. X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption-desorption, Fourier transform infrared (FTIR)-KBr, FTIR-pyrrole adsorption, hydrogen temperature-programmed reduction (H₂-TPR), and thermogravimetric analysis (TGA) were used to examine the catalytic properties. The Ru-FSMOR catalyst demonstrated substantially improved catalytic capacity at 450 °C, with 84% conversion of CO and 78% CH₄ yield compared to other catalysts. In addition, the Ru-FSMOR demonstrated excellent thermal stability, as evidenced by the absence of any deactivation after 100 h. Multiple factors, including high surface area, basicity, and the presence of uniformly distributed Ru, which served as CO and H₂ adsorption sites, significantly improve the CO methanation activity. The Ru-FSMOR exhibited optimum metal-support interaction amongst the series of catalysts evaluated, inhibiting crystallite movement and protecting against coke deposits. Additionally, in-situ FTIR spectroscopy revealed that CO and H₂ molecules are activated by linear adsorption of CO* as intermediates. These disintegrate into immobilized C*, which undergoes hydrogenation during CO methanation to produce methane.