Sorbitol Derived Carbon Coated Alumina Composite as a Promising Support for CoMoS Hydrotreating Catalyst

The beneficial impact of carbon coated alumina (C@Al2O3) implemented as support for the CoMoS hydrotreating catalyst has been demonstrated. A series of C@Al2O3 supports with varying carbon contents were obtained by pyrolysis of sorbitol preliminarily impregnated in alumina from an aqueous solution. It was found that carbon coating positively affects the formation of the high-active CoMoS phase. However, control of the carbon content from 2.3 to 11.3 wt % is essential to maintain the sulfide particles dispersion and textural properties. CoMoS/C@Al2O3 catalysts demonstrated superior hydrodesulfurization activity compared with CoMoS/Al2O3. The hydrodenitrogenation activity of most CoMoS/C@Al2O3 samples is similar to CoMoS/Al2O3 but decreases when the carbon content in the support exceeds 11.3 wt %. The determining factor in improving the CoMoS/C@Al2O3 hydrodesulfurization activity is the formation of defective graphene fragments, which partially cover the alumina surface and help to reduce the support acidity and, therefore, metal–support interaction while maintaining the textural characteristics.