The performance of Rh/SiO2-Al2O3 catalysts in methycyclohexane cracking reaction

•Rh/SiO2-Al2O3 catalysts are first investigated in cracking reaction of methycyclohexane.•Rh/S60 (the mass fraction of SiO2 is 60 wt.%) has the best catalytic activity and high-temperature stability.•Heat sink obtained on Rh/S60 is up to 3.85 MJ/kg.•The reaction activity evolves regularly with strong Lewis acid sites.

A series of amorphous SiO2-Al2O3 composites oxides with varying content of SiO2 were prepared by sol-gel method and used as the supports of Rh-based catalysts. The as-prepared catalysts were evaluated in the cracking reaction of methycyclohexane at high temperature of 600-750 °C and high pressure of 4 MPa. It was found that Rh/SiO2-Al2O3 catalysts exhibited better cracking activity than thermal cracking in parallel operating conditions. That was in good consistent with a substantial increment of strong Lewis acid sites in these Rh/SiO2-Al2O3 catalysts. Furthermore, catalytic activity of these Rh-supported catalysts greatly depended on the content of SiO2, which firstly increased with the content of SiO2, till 60 wt.%, and then declined when SiO2 occupied the overwhelming majority (85 wt.% and 100 wt.%) in the catalysts. Particularly, Rh/S60 (the mass fraction of SiO2 is 60 wt.%) achieved the best catalytic performance with regard to the gas yield, methycyclohexane conversion and heat sink which was respectively increased by 56.1%, 16.0%, 0.28 MJ/kg in comparison to thermal cracking at 675 °C.