Effect of carbon on the hydrodesulfurization activity of MoCo catalysts supported on zeolite/ active carbon hybrid supports

Abstract

A series of catalysts of cobalt (Co) and molybdenum (Mo) loaded on zeolite (Z) support decorated with different weight percent of activated carbon (AC), namely ZMoCo, ZACMoCo25%, ZACMoCo50%, and ZACMoCo75%, were newly prepared, characterized by using various techniques to reveal the structural, textural, surface composition and thermal behavior of both hybrid supports and supported bimetallic catalysts, followed by the evaluation of the supported bimetallic catalysts in ultra-deep hydrodesulfurization reaction. The loading of Co and Mo nanoparticles, as well as carbon, perturbed the zeolite lattice, but the structural crystallinity was largely preserved with low weight percent composition of carbon in the hybrid supports. The ZAC75% hybrid support showed significant loss of crystallinity, but this seemed to be largely redeemed with the incorporation of Co and Mo nanoparticles, as in the case of ZACMoCo75%. The progressive decrease in relative crystallinity (RC) with an increase in the amount of carbon, in both hybrid supports and supported bimetallic catalysts, could be due to the dilution effect of the hybrid supports. Importantly, the decoration of Y zeolite with carbon from waste rubber tyre offered a new metal-free approach to modify zeolite support for hydrodesulfurization MoCo catalysts. Optimum loading of carbon onto zeolite support offered uniform mesoporous structure, moderate acidity, and better active metal dispersion in the carbon-decorated zeolite-supported MoCo catalysts. The hybrid support ZAC50% showed better dispersion of metal nanoparticles to form ZACMoCo50% with preserved structural, textural and surface functionalities and reduced acidity that enabled its better performance of 98% conversion (turn over number, TON, of 7.84 at 6 h reaction time) in hydrodesulfurization of model fuel.