Role of free radicals in hydroprocessing of coal liquids

Carbonization of liquid fossil fuels at hydroprocessing temperatures of around 350/degree/C manifests itself as coking of catalysts and fouling of processing equipment. Catalyst coking is believed to be at least partly due to free radical reactions which cause condensation and polymerization of small molecules. An earlier study on hydrogenation of model compounds indicated that addition of an organometallic compound, bis (cyclopentadieny) titanium (IV) dichloride known as titanocene dichloride to the feed affected the coke formation probably by changing the mechanisms of free radical reactions (Tescheikuna and Seapan 1985). Therefore, in this project we conducted a study, using an SRC-II middle distillate and an SRC-II process solvent, to evaluate the role of free radicals and titanocene dichloride in hydrotreatment processes.