Both, physical solvents (Rectisol, Selexol, Benfield) and chemical solvents (amines: MEA, DGA, DEA, DIPA and MDEA) are widely used in oil refineries and natural gas processing plants for removing acid gases. Because these systems simply remove H2S the acid gas must then be routed to a sulfur recovery unit. The LO CAT® technology, with its “autocirculation” design, was first licensed to treat acid gas in 1982 The continued success of the LO CAT® technology on acid gas applications has lead to in excess of 60 acid gas treatment installations worldwide, making this the largest single user segment for the technology.