Fabrication and Performance of xMnyCe/Hexagonal Mesoporous Silica Sorbents with Wormhole-Like Framework for Hot Coal Gas Desulfurization

Abstract

A series of xMnyCe/hexagonal mesoporous silica (HMS) sorbents with wormhole-like structure was prepared by a sol−gel method, and their performance for hot coal gas desulfurization was investigated at 600 °C. All xMnyCe/HMS sorbents exhibited high breakthrough sulfur capacity, and the utilization of these sorbents was much higher than that of 10Mn/HMS. The breakthrough sulfur capacity over 4Mn1Ce/HMS sorbents was 121.7 mg of S/g of sorbent with the utilization of 82.4%. Such a behavior was maintained in eight consecutive desulfurization−regeneration cycles. The effects of the desulfurization temperature, H 2 concentration, and 7% steam on the performance of 4Mn1Ce/HMS were examined. The fresh, used, and regenerated samples were characterized by means of X-ray diffraction, N 2 adsorption, Fourier transform infrared absorption spectroscopy, and high-resolution transmission electron microscopy techniques. The results confirmed that the manganese oxide was dispersed highly on the HMS support because of the synergetic effects of manganese oxide and ceria oxide, and the wormhole-like structure in sorbents promoted the diffusion of H 2 S molecules. The Brunauer−Emmett−Teller results revealed that the wormhole-like mesoporous structure in sorbents remained intact even after the eighth successive desulfurization/regeneration cycle.

CeO 2 –MnO x /ZSM-5 sorbents for H 2 S removal at high temperature

“…It has been reported that the decline of the sulfur capacity over Mn-based sorbents was mainly attributed to the formation of sulfate, such as MnSO 4 , during sulfidation [20]. The specific absorption peaks of MnSO 4 at 625, 652, and 1013 cm À1 were not detected over the used sample probably contributed to the high sulfur capacity of 5Ce5Mn/ZSM-5 [34]. Table 1 BET specific surface area (S BET ), external specific surface area (S exter ), internal specific surface area (S inter ), total pore volume (V total ), micropore volume (V micro ), micropore ratio (X micro = V micro /V total ), average pore diameter (D aver ), the max aperture (D max ) of CeO 2 -MnO x /ZSM-5.…”

Tea Garden Lateritic Soil as a High-Temperature Desulfurization Sorbent: Effect of Oxygen on Regeneration Process

“…To understand the SO 2 evolution during the regeneration process, the sulfided lateritic soil was regenerated with air and diluted O 2 , and the outlet concentration of SO 2 was systematically recorded for the multiple regenerating cycles. As shown in Figure 1, the regeneration time ranged between 80 and 100 min when the diluted O 2 was used as a regenerating gas, whereas a very rapid regenerating time can be found when the air was used.…”

“…One of the crucial criteria in the development of the HGD for IGCC and SOFC is the need for a high sulfur capacity, low overall cost, high utilization, eco-friendly, and regenerable sorbent [1,2]. Based on the investigation of previous studies, Fe, Cu, Zn, Mn, V, and Co oxides have been paid much attention because of their thermodynamic feasibility, reactivity, and regeneration property [3][4][5][6].…”

Fabrication and Fractality of Fe2O3-CeO2/ZSM-5 Composites for High-Temperature Desulfurization

“…When the reaction temperature increases from 600 to 700 °C, the breakthrough time and sulfur capacity drop from 20 min and 1020 µmol S/g to 10 min and 408 µmol S/g correspondingly, and the breakthrough curve becomes flatter with lower slope, possibly due to the limitation of H2S diffusion for the reason that some active phases sinter or aggregate at 700 °C. Thus, the optimum temperature of sulfidation process is 600 °C [22,23].…”

“…The H 2 S reaction rate with metal oxides and the H 2 S diffusion rate can be promoted by increasing the reaction temperatures, the breakthrough time of 5 min and sulfur capacity of 408 µmol S/g over 5Fe5Ce/ZSM-5 at 500 • C are very low by the reason of lower H 2 S diffusion rate, and only the metal oxides on the sorbent surface react (Figure 5b). When the reaction temperature increases from 600 to 700 • C, the breakthrough time and sulfur capacity drop from 20 min and 1020 µmol S/g to 10 min and 408 µmol S/g correspondingly, and the breakthrough curve becomes flatter with lower slope, possibly due to the limitation of H 2 S diffusion for the reason that some active phases sinter or aggregate at 700 • C. Thus, the optimum temperature of sulfidation process is 600 • C [22,23].…”