Ru nanoparticles deposited on amorphous aluminosilicates as efficient low-temperature catalysts for hydrocracking of n-hexadecane

Several Ru catalysts deposited on amorphous aluminosilicate supports of different types (Al-MCM-41, Al-SBA-15 and aluminosilicate meso-cellular foam Al-MCF) with variable textural and acidic characteristics were prepared. The obtained catalysts were investigated in the hydrocracking of n -hexadecane in a continuous fixed-bed reactor yielding hydrocarbons in the jet fuel range. Efficient catalytic performance (45 – 60% conversion at 220 o C) at comparatively low temperatures (200 – 240 o C) resulting mainly in linear C10 – C15 alkanes was observed. More stable catalytic performance of Ru/Al-MCF was attributed to more open mesoporous structure of the initial supports in comparison with Al-MCM-41 and Al-SBA-15 possessing smaller cylindrical pores or micropores, respectively, which can be blocked with the reaction intermediates/coke. In terms of n -hexadecane conversion, the catalysts can be ranged in the following order: Ru/Al-MCF ˃ Ru/Al-SBA-15 ˃ Ru/Al-MCM-41 which correlates with the density of Brønsted acid sites calculated as the ratio of their concentration to the mesopore specific surface area. The synthesized materials provide high selectivity towards normal alkanes compared to corresponding isomers ( normal/iso ratio up to ca. 240). The corresponding normal/iso ratio is decreased in the following range: Ru/Al-MCM-41 ˃ Ru/Al-SBA-15 ˃ Ru/Al-MCF and can be correlated with the fraction of strong Brønsted acid sites which promote isomerization. • Aluminosilicate-supported Ru catalysts for continuous hydrocracking of n -hexadecane • Highly active at low temperatures (200 – 240 o C) yielding linear C10 – C15 alkanes • Catalytic activity correlated with the density of Brønsted acid sites • Higher degree of intimacy between acid and metal sites for Ru/Al-MCF • An extremal dependence of the TOF values on the site density