Arsenic management in shale oil upgrading

Although the timing remains uncertain, the production of synthetic crude from oil shale seems to be a likely response to diminishing petroleum reserves. Although not unique to shale oil, the presence of arsenic, ranging in concentration from a few to over 100 parts per million, poses a special concern.Arsenic is typically removed from the shale oil by a hydro-processing technique and is concentrated on a catalyst as thermally stable metal arsenides and metal arsenous sulfides. Because this arsenic is still slightly soluble in water, making the spent catalyst a hazardous material, passivation and extraction techniques were investigated to make the catalyst safe for disposal. Passivation techniques were not successful. While extraction procedures were capable of removing over 75% of the arsenic, treated material may still be acceptable.