High catalytic performance of crystalline facet‐engineered nanostructure γ ‐ Al 2 O 3 supported Ni catalyst for optimizing benzene hydrogenation

Abstract The petrochemical industry is developing new catalysts and processes for saturating aromatics to improve fuel ignition quality and cetane number, leading to better combustion. Nanostructures of γ ‐Al 2 O 3 with different facets—nanorods exposed by (111) and (222) facets, nanocubes enclosed by (200) facets, and nanosheets exposed by (220) facets—were synthesized and decorated with Ni nanoparticles. Detailed physicochemical characterizations showed that optimized adsorption strength for benzene and increased chemisorption capacity of benzene on medium‐strength acid sites were obtained from the progressive exposure of Ni/ γ ‐Al 2 O 3 (111), (200), (220), and (222) facets. The performance and activity of (2 wt.%) Ni/ γ ‐Al 2 O 3 catalyst in the hydrogenation of benzene reaction were studied in a high‐pressure continuous down flow catalytic fixed bed reactor. Two parameters of the reactor, such as pressure and temperature, were varied, keeping the liquid hourly space velocity (LHSV) at 2 min −1 to understand the effect on benzene conversion. It was observed that benzene conversion was increased with increasing H 2 pressure up to 15 bar and beyond that slightly decreased to 25 bar. Additionally, the benzene conversion is dependent upon temperature and shows a maximum at 330°C and activation energy found to be 23.24 kJ/mol. The power law model of hydrogenation of benzene gives a perfect fit on data, and it was found that the order of the H 2 shows a 1st order reaction, whereas the order of benzene is 0.8 (close to 1st order). It was found that (2 wt.%) Ni/ γ ‐Al 2 O 3 catalyst shows 94% benzene conversion into cyclohexane at moderate temperature and pressure.