Abstract: A process for removing hydrogen sulfide from natural gas and other gas streams. By passing a natural gas or other gas stream having a hydrogen sulfide (H.sub.2 S) component through an aqueous solution of copper (II) ions (Cu.sup.++), the hydrogen sulfide component is converted to copper sulfide (CuS). The copper (II) ion solution is prepared by admixing powdered copper (Cu) with an aqueous solution of nitric acid (HNO.sub.3). The copper (II) ion solution is regenerated from the copper sulfide by treatment with nitric acid which liberates nitrogen dioxide (NO.sub.2). The nitrogen dioxide is used to generate nitric acid for the copper sulfide regeneration stage. In another aspect, a reaction vessel is provided which includes a centrally disposed circulation tube that enhances the mass transfer and circulation characteristics of gas purification processes.