Vapour phase hydrodeoxygenation of anisole over ruthenium and nickel supported mesoporous aluminosilicate

Abstract

Mesoporous aluminosilicate (Al-SBA-15) support synthesised via a direct hydrothermal method was post loaded with monometals such as 1.0 wt% RuO₂ and 7.0 wt% NiO separately. Different weight percentages of bimetallic catalysts such as RuO₂ (0.2–1.0 wt%) with 7.0 wt% NiO were loaded jointly on mesoporous Al-SBA-15 support by a wet impregnation method for hydrodeoxygenation of anisole. The XRD and BET results revealed that the materials were hexagonally ordered, indicating the presence of mesoporosity. NH₃-TPD results confirmed the presence of acidic sites on materials, which enhanced the HDO activity of anisole. The oxidation state of Ni²⁺ and Ru⁴⁺ was confirmed by XPS analysis. H₂-TPR revealed the strong metal-support interaction in monometal catalysts of 7.0 wt% NiO, whereas in the case of bimetallic catalysts the reduction temperature of Ni was lowered below 440 °C by addition of Ru, which is lower than the that of 7.0 wt% NiO (524 °C). HR-TEM images further confirmed the presence of the mesoporous nature along with RuO₂ and NiO crystallites largely located over the surface of Al-SBA-15. The activity of all the synthesised catalysts was tested over vapour phase hydrodeoxygenation of anisole (biomass compound). Variation in temperature and time-on-stream with atmospheric pressure was optimised to obtain high conversion and selectivity. A reaction temperature of 400 °C was found to be optimum. The 1.0 wt% RuO₂/7.0 wt% NiO catalyst gave the highest conversion of about 46% of anisole and selectivity towards benzene of 45%. Bimetallic catalysts (1.0 wt% RuO₂/7.0 wt% NiO) showed high activity compared with monometallic catalysts (1.0 wt% RuO₂ and 7.0 wt% NiO) because of the synergism of Ni and Ru. Also the bimetallic catalysts showed good activity compared with other reported catalysts under variable experimental conditions.