Extrudutes of regenerable mixed-metal oxide sorbents including zinc ferrite, copper-modijied zinc ferrite, and zinc titanate were prepared and tested for their potential to remove hydrogen sulfide (H2S) from coal gasifier gas in a high-temperature high-pressure (HTHP) jixed-bed reactor. Reductions in H2S concentration from >10,000 parts per million b y volume (ppmv) to < I to 50 ppmv were achieved depending on sorbent, reactor temperature, and steam concentration. Zinc ferrite showed no apparent loss in capacity over 15 sulfidution-regeneration cycles, but underwent signijicant strength reduction at 5% steam due to soot formation. Zinc titanate exhibited excellent strength and capacity retention at 5% steam and temperatures up to 735°C.

Application of zinc ferrite, a regeneruble mixed metal oxide, for the removal of H2S from hot coal derived gas streams is limited to a maximum temperature of about 1,250"F (677°C) and to a minimum H2S concentration of about 5 ppmv in the cleaned gas. Four novel sorbents that have shown potential for ocercoming the limitations of zinc ferrite [ l , 41 were selected for development and bench-scale testing. Several variations of these mixed metal oxides were prepared, using different amounts of binders. They were tested in the presence of simulated coal gas using a thermogravimetric reactor (TGR) for selection of preparations possessing an adequate combination of reactivity, regenerability, capacity, and strength. Limited bench-scale tests were conducted in the presence of simulated fluidized-bed coal gas$er product gases at pressures from 1 to 2 MPa, temperatures from 525°C to 625°C and space velocities from 1,000 to 3000 Nm3/(m3 * h).

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