Selection and further activation of activated carbons for removal of nitrogen species in gas oil as a pretreatment for its deep hydrodesulfurization

The partial removal of nitrogen and refractory sulfur species from gas oil was confirmed to be effective to achieve deep hydrodesulfurization. Such removal was effectively performed over activated carbon materials that were further activated by oxidation, followed by heat treatment, to maximize the adsorption capacity of conventional materials for nitrogen and refractory sulfur species. Activation with particular oxidants such as HNO3, H2SO4, and H2O2, followed by heat treatment at their appropriate temperature, dramatically improved the adsorption capacity for nitrogen species by introducing the particular oxygen functional groups on activated carbon. From the correlation between the structure of carbon material and the adsorption capacity for nitrogen and sulfur, particular oxygen groups that release CO at a temperature of 600-800 degreesC in a helium atmosphere and the surface area of the carbon materials are keys for the adsorption of nitrogen and sulfur species.