Preparation and improvement of nickel catalyst supported ordered mesoporous spherical silica for thermocatalytic decomposition of methane

Abstract

The thermocatalytic alteration of CH4 into highly pure hydrogen and filaments of carbon was investigated on a series of Ni-catalysts with various contents (25, 40, 55, and 70 wt%) supported mesoporous spherical SiO2. The silica with ordered structure and high specific surface area (1136 m2/g) was synthesized using the Stöber technique with TEOS as a silica precursor and CTAB as the template in a simple synthesis system of aqueous-phase. This technique led to the preparation of mesoporous spherical silica. The prepared samples were characterized using BET, TPR, XRD, TPO, and SEM analyses. The prepared catalysts with different nickel loading showed the BET surface area ranging from 225.0 to 725.7 m2/g. These results indicated that an increase in nickel content decreases the surface area and leads to a subsequent collapse of a pore structure. SEM analysis confirmed a spherical nanostructure of catalysts and revealed that with the increase in loading of Ni, the particle size enlarged, because of the agglomeration of the particles. The results implied that the high methane conversion of 54% obtained over the 55 wt% Ni/SiO2 at 575 °C and this sample had higher stability at lower reaction temperature than the other prepared catalysts, slowly deactivation was observed for this catalyst at a period of 300 min of time on stream.