Study of mayenite produced from waste eggshell as support for Ni–Co catalysts for biomass tar cracking

Abstract

Ultrasonication-promoted synthesis was applied to produce mayenite (M-CES) with properties similar to mayenite produced with commercial reagents, using calcined eggshell waste as a calcium source. Monometallic 10Ni/M-CES (10 wt.% Ni) and 10Co/M-CES (10 wt.% Co) and bimetallic 5Ni5Co/M-CES (5 wt.% Ni and 5 wt.% Co) catalysts were synthesized by the wet impregnation method. Catalyst 10Co/M-CES showed a noticeably lower metal dispersion when compared to the Ni-containing catalysts. 5Ni5Co/M-CES bimetallic catalyst showed the highest metal dispersion, and XRD analysis proved the Ni–Co alloy formation. The performance of Ni–Co catalysts for hydrocarbon cracking was evaluated by methane and propane catalytic decomposition. The alloy formation between Ni and Co in the bimetallic catalyst provided a reduction in the start temperature of the cracking reaction of approximately 80 °C and 110 °C for methane and propane, respectively, when compared to monometallic catalysts. A synergistic effect was also observed by a decrease in carbon deposition and an increase in the catalytic activity of 5Ni5Co/M-CES. The use of eggshell waste to produce mayenite support for tar cracking catalysts has proved to be attractive to add value to the eggshell waste.