Rhodium-Based Catalysts: An Impact of the Support Nature on the Catalytic Cyclohexane Ring Opening

Because of the growing demand for high-quality fuels, the light cycle oil fraction improvement including cetane number improvement is important. The main way to reach this improvement is the ring opening of cyclic hydrocarbons, and a highly effective catalyst should be found. Cyclohexane ring openings are a possible option to investigate the catalyst activity. In this work, we investigated rhodium-loaded catalysts prepared using the commercially available industrial supports: single-component ones, SiO₂ and Al₂O₃; and mixed oxides CaO + MgO + Al₂O₃ and Na₂O + SiO₂ + Al₂O₃. The catalysts were prepared by incipient wetness impregnation and investigated by N₂ low-temperature adsorption-desorption, XRD, XPS, DRS UV-Vis and DRIFT spectroscopy, SEM, and TEM with EDX. The catalytic tests were performed in cyclohexane ring opening in the range of 275-325 °C. The best result was demonstrated by the sample 1Rh/CaMgAlO: the selectivity to n-hexane was about 75% while the cyclohexane conversion was about 25% at 275 °C. The space-time yield was up to 12 mmol_n-hexane g_cat^-1h^-1.