Resource Utilization of Spent Activated Coke as an Efficient Material for Simultaneous Removal of COS and H₂S

Abstract

The desulfurization of blast furnace gas (BFG) is highly desired by iron and steel enterprises to realize its resource utilization with no environmental pollution. In this work, spent activated coke (SAC) modified by NaOH was innovatively reused as an efficient material for the removal of carbonyl sulfide (COS) and sulfuretted hydrogen (H 2 S) from BFG with admirable breakthrough sulfur capacities of 126.58 and 141.62 mg/g, respectively, and 100% removal efficiency of both COS and H 2 S could be reached with the total sulfur capacity of COS and H 2 S as high as 116.60 mg/g in the purification of the simulative BFG gas. The removal behaviors manifested that the removal process included catalytic hydrolysis of COS to H 2 S and subsequent oxidation of H 2 S to immobilize these sulfur species in the form of S 8 . The multiple structural characterizations (X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), H 2 -temperature-programmed reduction (TPR)) further revealed that the surface carbonyl and pyridine/pyrrolic groups together with the loaded hydroxyl ion enhanced the COS hydrolysis and the subsequent oxidation of H 2 S. The modified SAC possessed much richer pore structures and active groups than either fresh activated coke (FAC) or high specific surface area activated carbon (HAC). At the same time, a recycling scheme suitable for SAC after removing H 2 S and COS was proposed. The demonstrated excellent simultaneous removal capacity of COS and H 2 S over the modified SAC will provide a promising technical route for desulfurization of BFG with high efficiency and low cost.

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

“…K 2 CO 3 impregnation and N doping promote the removal of both COS and H 2 S, implying a synergistic effect. Figure f shows that ACC-N-8K clearly exhibits the highest combined capacity ( M C ) of 312.4 mg·g –1 , which far exceeds that of another reported carbon-based bifunctional catalyst ( M C = 116.6 mg·g –1 ) …”

“…Figure 1f shows that ACC-N-8K clearly exhibits the highest combined capacity (M C ) of 312.4 mg•g −1 , which far exceeds that of another reported carbonbased bifunctional catalyst (M C = 116.6 mg•g −1 ). 13 The H 2 S selectivity of AC, ACC, AC-N, AC-8K, and AC-N-8K during COS hydrolysis was investigated in the absence of H 2 S. As shown in Figure S4, all five samples have nearly 100% selectivity toward H 2 S during COS hydrolysis. However, the H 2 S selectivities of ACC, AC-8K, and AC-N-8K decrease after a certain period of time, which may be attributed to the production of S 2− and SO 4 2− .…”

“…16−19 In contrast, little research has been reported on the use of carbon materials for COS removal. Ma et al 13 reported a bifunctional catalyst prepared from waste-activated coke for the removal of COS and H 2 S. However, the combined capacity of this catalyst was only 116.6 mg•g −1 , which is not enough to meet the demand of practical industry applications. Notably, several studies have confirmed that N doping can significantly promote the functionalization of desulfurizers.…”

“…Due to the different physical and chemical properties of COS and H 2 S, their removal from BFG usually involves different methods, as shown in Figure S1. However, this stepwise removal process has various drawbacks. − Therefore, the development of a bifunctional desulfurizer that can satisfactorily remove both COS and H 2 S would be highly promising for replacing existing technology.…”

“…In recent years, carbon materials have shown promising applications in the field of H 2 S removal due to their excellent surface properties and easy functionalization. , Biochar carbon materials prepared by the carbonization and activation of plant wastes such as straw, leftover rice, and peanut shells can be used to effectively remove H 2 S from gas while also promoting the resourceful use of wastes. − In contrast, little research has been reported on the use of carbon materials for COS removal. Ma et al reported a bifunctional catalyst prepared from waste-activated coke for the removal of COS and H 2 S. However, the combined capacity of this catalyst was only 116.6 mg·g –1 , which is not enough to meet the demand of practical industry applications. Notably, several studies have confirmed that N doping can significantly promote the functionalization of desulfurizers.…”