This invention is an integrated process which removes acidic gases such as H.sub.2 S, COS and CO.sub.2 from raw synthesis gas. The H.sub.2 S and COS is concentrated and separately recovered. The separately recovered CO.sub.2 is used as a moderator with the purified syngas in a combustion turbine. The process comprises separating H.sub.2 S and COS from a raw synthesis gas by absorption with a liquid solvent, removing coabsorbed CO.sub.2 by stripping the solvent with nitrogen, separating the H.sub.2 S and COS from the solvent and recovering sulfur from the H.sub.2 S and COS. The energy value of the CO.sub.2 and its value as a diluent in reducing NO.sub.x is recovered by using the CO.sub.2 as a moderator during combustion of the purified synthesis gas in a gas turbine.