Facile synthesis of yttria-promoted nickel catalysts supported on MgO-MCM-41 for syngas production from greenhouse gases
Catalytic deactivation owing to agglomeration and metal particle sintering is a serious challenge in dry reforming of methane that encourages researchers to design anti-coke catalysts in a suitable route. Therefore, a series of yttrium oxide (Y2O3)-promoted Ni catalysts supported on magnesium oxide (MgO)-modified MCM-41 were successfully synthesized by the one-pot method. The catalyst characterization was done using X-ray diffraction (XRD), N2 adsorption-desorption, high-resolution transmission electron microscopy (HR-TEM), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), temperature-programmed oxidation (TPO) and scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray analysis (EDAX); after that, it was examined for methane reforming with CO2. The HR-TEM micrographs illustrated that the ordered mesoporous structure of the support remained even after the incorporation of the metallic ions. According to TPD results, the incorporation of Mg into mesoporous silica enhanced the basicity of the support surface. TPR results indicated that adding Mg in a one-pot way led to stronger interaction of metal particles with support and incorporating of yttria enhanced catalyst reducibility. Moreover, based on reforming results, the catalytic performance depended on yttria contents, as catalyst containing 2 wt% yttria possessed the highest NiO dispersion, oxygen vacancies, reducibility, CH4 conversion (79%), H2/CO ratio (0.85) and stability in time on stream (20 h). The TPO and microscopic observations of the spent catalysts revealed that a tip type of nanotube carbon deposited on the yttria-promoted catalyst surface inhibited catalyst deactivation. Therefore, 2Y2O3–Ni/MgO–MCM-41 catalyst can be a practical and environmental candidate for methane reforming with CO2.