Natural zeolite supported Ni catalysts for hydrodeoxygenation of anisole

Natural and synthetic (BEA, MOR) zeolite-supported nickel (similar to 5 wt%) catalysts were prepared and employed for the hydrogenation of toluene and hydrodeoxygenation of anisole in a continuous-flow reactor. Ni/BEA and Ni/MOR display a higher level of metal dispersion and stronger metal-support interaction compared to the Ni/NZ and Ni/Escott catalysts, resulting in a higher concentration of charge-compensating Ni species and a larger high-temperature reduction peak. The Ni/BEA and Ni/MOR also present a significant mass of low-temperature desorbed H-2 (centred at 150 degrees C) based on H-2-TPD, suggesting the H species are weakly adsorbed on small Ni clusters. In contrast, the H species were strongly adsorbed by the bulk Ni crystal over Ni/Escott and Ni/NZ, which were desorbed at maxima between 211 and 222 degrees C. We propose that the strongly adsorbed H species play a crucial role in the hydrogenation of toluene, leading to a significantly higher yield of methylcyclohexane over Ni/Escott and Ni/NZ compared to Ni/BEA and Ni/MOR. Both metal and acid sites are required in the hydrodeoxygenation of anisole. The strong Bronsted acid sites and numerous smaller Ni species over Ni/BEA facilitated the transalkylation of anisole to phenol and methylanisole and subsequently hydrogenolysis of phenol to benzene, followed by the hydrogenation of benzene to cyclohexane.

Automated summary

The study demonstrates that Ni/BEA and Ni/MOR catalysts show better performance in the hydrogenation of toluene, while Ni/BEA is more effective in the hydrodeoxygenation of anisole.