Abstract: The catalysts for selective terminal methyl removal via hydrogenation of aromatics were synthesized by modifying the carrier metal. The hydrodealkylation behavior of ethylbenzene over different catalyst systems was systematically investigated, and the optimal catalyst system was identified as Rh supported on an alumina (Al₂O₃) carrier through comparative analysis of reaction performance. Subsequently, the effects of Al2O3 support modification and active metal loading on catalytic performance were explored. The prepared catalysts were characterized using ammonia temperature-programmed desorption (NH₃-TPD) and pyridine infrared spectroscopy (Py-FTIR). The results revealed that the introduction of K₂O as a modifier effectively suppressed the surface acidity of the Al₂O₃ carrier, thereby enhancing the selectivity for terminal methyl removal from C₂+ side chains in aromatics molecule. Among the synthesized K-modified Al₂O₃ catalysts, the 0.7% Rh-loaded catalyst exhibited the highest ethylbenzene conversion (60%) and optimal methyl removal selectivity. Notably, the molar ratio of toluene to benzene in the products increased to 5.9 under optimized conditions.Additionally, the effects of reaction pressure, temperature and hydrocarbon ratio conditions on catalytic performance were systematically investigated.

Key words: ethylbenzene, dealkalation, hydrogenation, terminal methyl, aromatics, acidity control