a reducing gas stream containing hydrogen , carbon monoxide and water , as steam , is passed through a molten sulfur to vaporize sulfur . the gas stream containing the vaporized sulfur is passed through a catalytic conversion zone where at a controlled temperature of from about 500 ° to about 800 ° f sulfur is converted to hydrogen sulfide . the introduced steam optionally coupled with a water quench following hydrogenation of sulfur serves to suppress carbonyl sulfide and carbon disulfide formation .