Durable regenerable sorbent pellets for removal of hydrogen sulfide from coal gas

Durable sorbent pellets chemically and physically stable for use in multi-cycle sulfidation and regeneration processes at temperatures over 260.degree. C. (500.degree. F.) consisting of a mixture of the following components:

• a material reactive with hydrogen sulfide and selected from the group consisting of metal oxides, acetates, formates, carbonates ad nitrates of zinc, copper, iron, manganese, chromium, and mixtures thereof and having a particle size below 50 microns--30 to 65 weight percent;
• a diluent selected from the group consisting of, calcium sulfate, calcium phosphate, magnesium sulfate, and zinc silicate, and having a particle size less than 50 microns--20 to 40 weight percent;
• an inert material comprising particles having a particle size at least twice that of said material reactive with hydrogen sulfide selected from the group consisting of silica, silica gel, alumina, alumina gel, calcium sulfate (drierite), zinc silicate, and sand, wherein the particle size of said inert material is chosen to create additional voids between the components, thus increasing the porosity of the sorbent pellets --2 to 40 weight percent;
• a binder unreactive with hydrogen sulfide, having a particle size less than said inert material, and selected from the group consisting of bentonite, kaolinite, and cement and mixtures thereof--2 to 45 weight percent;
• a promoter selected from the group consisting of oxides and salts of copper, cobalt, manganese, nickel and mixtures thereof--an amount greater than zero and up to 10 weight percent;
• said mixture having been moistened with water, formed into pellets, dried, and calcined at a temperature above 538.degree. C. (1,000.degree. F.), but low enough to avoid a chemical reaction of said material reactive with hydrogen sulfide with said diluent;
• and
• said material reactive with hydrogen sulfide being unreactive with all other components of said mixture at said calcination temperature.