Mn-Cu and Mn-Cu-V Mixed-Oxide Regenerable Sorbents for Hot Gas Desulfurization

Porous Mn-Cu and Mn-Cu-V mixed-oxide sorbents prepared by the complexation technique were tested for hightemperature removal of H2S in the presence of hydrogen gas. Sorption experiments carried out at 627 (degree)C in a fixedbed reactor showed higher reactivity and also higher sulfur retention capacity (over 0.15 g of S/g of sorbent) for the Mn-Cu mixed oxide than for the Mn-Cu-V mixed oxide. Successive sulfidation-regeneration cycles demonstrated that the Mn-Cu mixed oxide was also more stable than Mn-Cu-V, maintaining its activity and about 90% of its sulfur retention capacity at the end of five cycles. Although formation of some MnSO4 was observed during regeneration at 700 (degree)C with a gas mixture containing 6% oxygen in nitrogen, this did not cause significant reduction in the activity of this mixed-oxide sorbent. It was also shown that a previously proposed deactivation model gave good predictions of the experimental breakthrough curves obtained with these sorbents.