Coke minimization via SiC formation in dry reforming of methane conducted in the presence of Ni-based core–shell microsphere catalysts

Abstract

Mesoporous Ni/Si microsphere catalysts were synthesized with a modified sol–gel microencapsulation method and their activity was tested in dry reforming of methane (DRM) reaction. Results indicated comparable conversion values and H2/CO ratios with other catalysts reported in literature. Activity loss of 5% determined with time on stream analysis of 5% Ni/Si catalyst revealed that sustainable production could have been possible in the presence of these catalysts. Coke deposition which was frequently stated as the reason of activity loss was not observed with Ni/Si microsphere catalysts. Taking into account the impossibility of eliminating methane cracking and Boudard reaction during DRM, we should come up with an explanation of the absence of coke. This explanation was provided by silicon carbide (SiC) formation which consumed the coke deposited on the catalyst. Characterization analyses conducted at spent catalysts validated both the absence of coke and formation of SiC during DRM.