Selectivity of layered double hydroxides and their derivative mixed metal oxides as sorbents of hydrogen sulfide

In the context of finding high efficient sorbent materials for removing hydrogen sulfide (H2S) from air stream, a screening study was performed to find the best combination of metals for the synthesis of layered double hydroxides (LDHs) and their derivative mixed metal oxides. Based on selectivity of 998 natural mineral species of sulfur-containing compounds, Cu2+, Ni2+ and Zn2+ were selected as divalent metals, and Fe3+, Al3+ and Cr3+ as trivalent metals to synthesis the LDHs sorbents. 10 LDHs materials and their calcined mixed metal oxides, Ni0.66Al0.34, Cu0.35Ni0.32Al0.33, Zn0.66Al0.34, Cu0.36Zn0.32Al0.32, Ni0.64Fe0.36, Cu0.35Ni0.31Fe0.34, Ni0.66Cr0.34, Cu0.35Ni0.31Cr0.34, Zn0.66Cr0.34, Cu0.33Zn0.32Cr0.35 were synthesized, characterized chemically and physically, and then tested using breakthrough test to determine their sulfur uptake. Ni0.64Fe0.36 mixed metal oxides was found to have the best uptake of hydrogen sulfide (136 mg H2S/g). Regeneration of spent Ni0.64Fe0.36 mixed metal oxides was studied using two different mixture solutions, NaCl/NaOH and acetate-buffer/NaCl/NaOH. The latter mixture successfully desorbed the sulfur from the Ni0.64Fe0.36 sorbent for 2 cycles of regeneration/sorption.