A system for reducing SO.sub.2 emissions comprises a hydrogenation reactor, a tail gas cooler, a contact condenser, a hydrolysis reactor, and an absorber. The hydrogenation reactor is configured to receive a Claus tail gas and convert at least a portion of SO.sub.2 in the Claus tail gas to H.sub.2S to produce a hydrogenated Claus tail gas stream. The hydrolysis reactor is configured to convert at least a portion of COS to H.sub.2S. The absorber comprises an amine-based solvent and is configured to absorb at least a portion of the H.sub.2S and recycle the H.sub.2S to the Claus plant.

A process for the production of synthesis gas from coke is described herein. The process comprises the steps of: (a) subjecting hard coal to dry pyrolysis, resulting in the production of a gas mixture containing hydrogen, methane, nitrogen and carbon monoxide as major constituents and carbon sulphides as minor constituents; (b) subjecting the gas mixture to hydrogenation at a temperature in the range of 200 to 280 C. over a sulphidic cobalt molybdenum catalyst provided on an aluminium oxide carrier material; and (c) separating the hydrogen sulphide obtained from hydrogenation from the gas mixture.

Contemplated systems and methods for removing polysulfides and hydrogen sulfide from liquid sulfur of a Claus plant include (a) physically separated steps of catalytic decomposition of polysulfides and gas stripping, or (b) use of the stripping gas as the continuous phase in a packed column with decomposition catalyst to so avoid catalyst attrition.

A system for reducing SO.sub.2 emissions comprises a hydrogenation reactor, a tail gas cooler, a contact condenser, a hydrolysis reactor, and an absorber. The hydrogenation reactor is configured to receive a Claus tail gas and convert at least a portion of SO.sub.2 in the Claus tail gas to H.sub.2S to produce a hydrogenated Claus tail gas stream. The hydrolysis reactor is configured to convert at least a portion of COS to H.sub.2S. The absorber comprises an amine-based solvent and is configured to absorb at least a portion of the H.sub.2S and recycle the H.sub.2S to the Claus plant.