Amino-modified molecular sieves for adsorptive removal of H2S from natural gas

Amine-modified MCM-41 adsorbents (APTMS/MCM-41, PEI/MCM-41 and AAPTS/MCM-41) were prepared and characterized by XRD, N₂ adsorption–desorption, FT-IR, TEM, SEM and TG-DTA. The performance of each adsorbent in a fixed adsorption bed for H₂S removal was measured using a mixture of oxygen, nitrogen and hydrogen sulfide gases. It was found that the specific surface area decreased and the topography changed significantly after the use of each modified adsorbent. Nevertheless, all amine-modified MCM-41 adsorbents retained mesoporous silica of MCM-41. The H₂S removal rate and saturated H₂S capacity of APTMS/MCM-41 improved from 32.3% to 54.2% and 119.5 to 134.4 mg g⁻¹, respectively, compared with that of MCM-41, and it showed the best performance among all adsorbents. APTMS/MCM-41, PEI/MCM-41 and AAPTS/MCM-41 were regenerated by maintaining at 423, 523 and 373 K in nitrogen for 3 h, respectively, and thus possessed high regenerability.

Several amine-modified MCM-41 adsorbents (APTMS/MCM-41, PEI/MCM-41, AAPTS/MCM-41) by the grafting method were prepared, in which APTMS/MCM-41 showed much better adsorptive desulfurization performance and regenerability than the others.