Ultrasonic-assisted preparation of highly active Co3O4/MCM-41 adsorbent and its desulfurization performance for low H2S concentration gas.

Co3O4/MCM-41 adsorbents were successfully prepared by ultrasonic assisted impregnation (UAI) and traditional mechanical stirring impregnation (TMI) technologies and characterized by X-ray diffraction (XRD), N2 adsorption desorption, Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetry-differential thermal analysis (TG-DTA). The H2S removal performances for a simulated low H2S concentration gas were investigated in a fixed-bed. The effect of preparation and adsorption conditions on the H2S removal over Co3O4/MCM-41 were systematically examined. The results showed that UAI promotes more and well defined highly dispersed active Co3O4 phase on MCM-41. As compared to the Co3O4/MCM-41-T prepared via TMI, the saturated H2S capacity of Co3O4/MCM-41-U prepared via UAI improved by 33.2%. The desulfurization performance of adsorbents decreased in the order of Co3O4/MCM-41-U > Co3O4/MCM-41-T > MCM-41. The Co3O4/MCM-41-U prepared using Co(NO3)2 concentration of 10%, ultrasonic time of 2 h, calcination temperature of 550 °C and calcination time of 3 h exhibited the best H2S removal efficiency. At adsorption temperature of 25 °C with model gas flowrate of 20 mL min-1, the breakthrough time of Co3O4/MCM-41-U was 10 min, and the saturated H2S capacity and H2S removal rate was 52.6 mg g-1 and 47.8%, respectively.

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.