Optimization of catalyst activity and stability in the m-cresol hydrodeoxygenation through Ni particle size control

By taking advantage of different nanoparticle size control methodologies, the precise role of Ni particle size (from 1 nm to 9 nm) was evaluated in the HDO of m-cresol in vapor phase at 573 K under atmospheric pressure. The m-cresol HDO reaction pathways were found to be Ni-particle size dependent. The direct deoxygenation (DDO) rate increased by 10 times when decreasing Ni particle size from 9 nm to 1 nm, while the hydrogenation (HYD) and hydrogenolysis (HYG) rates moderately increased. By applying a geometric model, reaction rates were correlated to the different type of sites. Edges and corner sites (smaller particles) favor aromatics production (DDO route), while face sites (larger particles) favor both HYD and HYG routes. Catalysts partially deactivated due to coke formation, with only slight sintering observed for 1 nm Ni particles. Such findings may serve in the further preparation of active and selective catalysts for bio-oils upgrading into fuel.