Highly efficient Ru/TiO2 -NiAl mixed oxide catalysts for CO selective methanation in hydrogen-rich gas

Abstract

Selective CO methanation (CO-SMET) is viewed as an effective H2-rich gas purification technique for proton exchange membrane fuel cells. In this work, improved composite-supported Ru catalysts were developed for the CO-SMET process. Mixed metal oxides (MMOs) obtained by calcination of layered double hydroxides precursor were used as an effective catalyst supports. After incorporation of TiO2, the resulting TiO2-MMO composites were expected to have an enhanced catalytic performance. Therefore, a series of TiO2-NiAl layered double hydroxides was successfully prepared via 1-pot deposition method. After calcination, the derived TiO2-NiAl MMO-supported Ru catalysts obtained by impregnation method showed excellent catalytic performance for CO-SMET reaction. The catalyst could deeply remove the CO outlet concentration (<10 ppm) with a high selectivity (>50%) over the wide low-temperature window (175-260°C). Furthermore, the catalyst also showed high stability with no deactivation during a long-term durability test (120 h). Based on X-ray diffraction, Fourier transform infrared, Raman, thermogravimetric differential scanning calorimetry, N2 adsorption-desorption, temperature-programmed reduction, scanning electron microscopy, and transmission electron microscopy analyses, the enhanced catalytic performance of the TiO2-NiAl MMO-supported Ru catalyst was found to be related to the higher dispersion of Ru nanoparticles, partially reduced NiO species, and the increased specific surface area and structural stability of the support. The facile synthesis strategy proposed herein may open a new window for the efficient production of high-quality H2.