Highly Dispersed FeAg-MCM41 Catalyst for Medium-Temperature Hydrogen Sulfide Oxidation in Coke Oven Gas

Abstract

The traditional hydrolysis−cooling−adsorption process for coke oven gas (COG) desulfurization urgently needs to be improved because of its complex nature and high energy consumption. One promising alternative for replacing the last two steps is selective catalytic oxidation. However, most catalysts used in selective catalytic oxidation require a high temperature to achieve effective desulfurization. Herein, a robust 30Fe-MCM41 catalyst is developed for direct desulfurization at medium temperatures after hydrolysis. This catalyst exhibits excellent stability for over 300 h and a high breakthrough sulfur capacity (2327.6 mgS g cat −1). Introducing Ag into the 30Fe-MCM41 (30Fe5Ag-MCM41) catalyst further enhances the H 2 S removal efficiency and sulfur selectivity at 120 °C. Its outstanding performance can be attributed to the synergistic effect of Fe−Ag clusters. During H 2 S selective oxidation, Fe serves as the active site for H 2 S adsorption and dissociation, while Ag functions as the catalyst promoter, increasing Fe dispersion, reducing the oxidation capacity of the catalyst, improving the desorption capacity of sulfur, and facilitating the reaction between active oxygen species and [HS]. This process provides a potential route for enhancing COG desulfurization.

Iron-Based Catalysts Derived from Iron-Containing Sludge for Enhanced Catalytic Performance of H2S Selective Catalytic Oxidation

“…Due to the fact that O 2 , O 2 – , and O 2 2– species desorbed at similar temperatures, it is difficult to distinguish them based on their desorption temperature. Therefore, the desorption peak at low temperatures can be attributed to the desorption of chemically adsorbed oxygen (O ads , including O 2 , O 2 – , and O 2 2– ) species, while the desorption peak at medium to high temperatures and high temperatures can be assigned to the desorption of surface lattice oxygen (O latt ), and bulk lattice oxygen, respectively. , From Figure A, it can be observed that the sludge-based catalysts were composed of three oxygen desorption peaks. The desorption peaks at 30–300 and 300–500 °C were due to the desorption of surface adsorbed oxygen species (O ads ) and surface lattice oxygen (O latt ), while the desorption peaks above 500 °C were due to the desorption of bulk lattice oxygen species in the sludge-based catalysts.…”

“…According to the reports, the alkaline sites on the surface of the catalyst play a crucial role in the selective catalytic oxidation of H 2 S . In general, the H 2 S molecule needed to be dissociated into HS – on the alkaline sites before it can be further oxidized, while alkaline sites can promote this dissociation reaction, thus promoting its desulfurization performance. , Moreover, the large amount of elemental S generated during H 2 S selective catalytic oxidation contributed to increasing the colliding and merging probability of S atoms with each other, making it easier to form cyclic or chain-shaped S8 structures, which can be easily precipitated. As a result, it can be avoided to further oxidize into SO 2 , thus improving the S selectivity of the catalyst.…”

“…From Figure A, it can be seen that the peaks of Fe, Si, Al, Ca, K, and O elements are accurately identified in the full scan of the XPS spectrum, and the approximate content of the elements is shown in Table , indicating that the sludge-based catalysts were composed of multi-elements. As shown in Figure B, the fine spectrum of O 1s mainly includes surface lattice oxygen species (O latt ) at BE = 530.9 eV, surface-adsorbed oxygen species (O ads ) at BE = 531.7 eV, hydroxy oxygen species at BE = 533.1 eV. ,, According to the literature, surface-adsorbed oxygen with high mobility is the most active species in selective catalytic oxidation of H 2 S, and the number of surface-adsorbed oxygen means the rich surface oxygen vacancies. Generally, oxygen molecules in the reaction are activated by the abundant oxygen vacancies on the surface of the catalyst.…”

“…Furthermore, Figure C shows that the asymmetric peak of Fe 2p3/2 XPS and the peaks located at binding energies of 711.5, 714.8, and 718.5 eV can be attributed to Fe 2+ , Fe 3+ species and the satellite peaks of Fe 2+ species on the surface of sludge-based catalysts, respectively. ,, The integrated peak area of Fe 2+ and Fe 3+ was calculated, as shown in Table . In comparison to other sludge-based catalysts, S-500(2.0) had the biggest molar percentage of Fe 3+ species with 50.88%, which played a vital role in the adsorption of H 2 S molecules.…”

Cu/Biochar Bifunctional Catalytic Removal of COS and H2S:H2O Dissociation and CuO Anchoring Enhanced by Pyridine N

“…COS and H 2 S are well-known sulfur-containing substances that seriously impact the atmosphere, cause acid rain, endanger human health, and contribute to global climate change. − Blast furnace gas (BFG) is one of the three gas byproducts generated by the iron and steel industry. Due to its large output and low calorific value (about 3500 kJ/m 3 ), BFG is usually directly discharged.…”