NOVELTY - Oxidizing sulfur dioxide at high concentration into sulfur trioxide comprises contacting a gas containing sulfur dioxide at 3 wt.% or more, and a supply of oxygen molecules, with an activated carbon preparation that contains type(s) of catalytic metal dopant(s); and using anhydrous liquid solvent having a low dielectric constant as a stripping agent to remove sulfur trioxide molecules from activated carbon preparation.    USE - For oxidizing sulfur dioxide into sulfur trioxide.    ADVANTAGE - The method improves the efficiency and reduces the costs of SO2 to SO3 oxidation. It enables SO2 to SO3 oxidation in ways that generate less toxic or hazardous waste, using anhydrous systems that avoid or minimize any water or salt formation, and also minimize sulfuric acid formation. It can properly and efficiently utilize large amounts of energy that will be released when large quantities of SO2 are oxidized to SO3.    DETAILED DESCRIPTION - Oxidizing sulfur dioxide at high concentration into sulfur trioxide comprises contacting a gas containing sulfur dioxide (SO2) at 3 wt.% or more, and a supply of oxygen molecules, with an activated carbon preparation that contains type(s) of catalytic metal dopant(s), in a reactor vessel that also contains anhydrous liquid solvent(s) having a low dielectric constant, under temperature and pressure conditions that promote oxidation of SO2 molecules to form SO3 molecules; and using anhydrous liquid solvent having a low dielectric constant as a stripping agent to remove sulfur trioxide molecules from activated carbon preparation.    An INDEPENDENT CLAIM is also included for a composition of matter for use in oxidizing sulfur dioxide at high concentration into sulfur trioxide (SO3), comprising activated carbon preparation that contains type(s) of catalytic metal dopant; and anhydrous liquid solvent(s) having a low dielectric constant, which is able to function as an effective stripping agent for removing SO3 molecules from activated carbon preparation.