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.