APCATB 147-2014-359

Highly active Ni-promoted mesostructured silica nanoparticles forCO2methanation

Mesostructured silica nanoparticles (MSN) and Ni loaded onto MSN (Ni/MSN) for the methanationof CO2were prepared by the sol–gel and impregnation methods. Catalytic testing was conducted inthe temperature range of 423–723 K under atmospheric pressure in the presence of H2. Ni supportedon MSN was compared with others types of support such as MCM-41 (Mobile Crystalline Material),HY (protonated Y zeolite), SiO2and -Al2O3. The activity of CO2methanation followed the order:Ni/MSN > Ni/MCM-41 > Ni/HY > Ni/SiO2> Ni/-Al2O3. The nitrogen physisorption and pyrrole adsorbedIR spectroscopy results indicated that the high activity of Ni/MSN is due to the presence of both intra-and inter-particle porosity which led to the high concentration of basic sites. In addition, the correlationbetween N–H band intensity and the turnover frequency revealed that the methanation activity increasedwith increasing of the concentration of basic sites. The presence of defect sites or oxygen vacancies in MSNwas responsible for the formation of surface carbon species, while Ni sites dissociated hydrogen to formatomic hydrogen. The surface carbon species then interacted with atomic hydrogen to form methane.The Ni/MSN catalyst performed with good stability and no deactivation up to 200 h.