While the H2S that was dissolved in the original crude oil was flashed off during production and at the start of processing; additional H2S is generated by the reduction of other sulfur compounds during the refining process. Any processing carried out on a sulfur-containing stream will generate a non-condensing overhead off gas that contains H2S: visbreaking, coking, fluidized-bed catalytic cracking, hydrotreating, hydrofining, and hydrodesulfurization. Merichem’s LO CAT® process has proven to be a highly effective desulfurization process that is capable of producing sulfur free off gases that are typically sent to the refinery fuel gas system. The LO CAT® technology was first licensed to treat a refinery overhead off gas stream in 1981. The continued success of the LO CAT® technology in refinery applications has lead to nearly two dozen installations worldwide.