Ultrasonic-assisted preparation of highly active Co 3 O 4 /MCM-41 adsorbent and its desulfurization performance for low H 2 S concentration gas.

Co 3 O 4 /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), N 2 adsorption desorption, Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetry-differential thermal analysis (TG-DTA). The H 2 S removal performances for a simulated low H 2 S concentration gas were investigated in a fixed-bed. The effect of preparation and adsorption conditions on the H 2 S removal over Co 3 O 4 /MCM-41 were systematically examined. The results showed that UAI promotes more and well defined highly dispersed active Co 3 O 4 phase on MCM-41. As compared to the Co 3 O 4 /MCM-41-T prepared via TMI, the saturated H 2 S capacity of Co 3 O 4 /MCM-41-U prepared via UAI improved by 33.2%. The desulfurization performance of adsorbents decreased in the order of Co 3 O 4 /MCM-41-U > Co 3 O 4 /MCM-41-T > MCM-41. The Co 3 O 4 /MCM-41-U prepared using Co(NO 3 ) 2 concentration of 10%, ultrasonic time of 2 h, calcination temperature of 550 °C and calcination time of 3 h exhibited the best H 2 S removal efficiency. At adsorption temperature of 25 °C with model gas flowrate of 20 mL min -1 , the breakthrough time of Co 3 O 4 /MCM-41-U was 10 min, and the saturated H 2 S capacity and H 2 S removal rate was 52.6 mg g -1 and 47.8%, respectively.