Reverse Conversion Treatment of Gaseous Sulfur Trioxide Using Metastable Sulfides from Sulfur-Rich Flue Gas

Abstract

Sulfur trioxide (SO 3 ) is an unstable pollutant, and its removal from the gas phase of industrial flue gas remains a significant challenge. Herein, we propose a reverse conversion treatment (RCT) strategy to reduce S(VI) in SO 3 to S(IV) by combining bench-scale experiments and theoretical studies. We first demonstrated that metastable sulfides can break the S−O bond in SO 3 , leading to the re-formation of sulfur dioxide (SO 2 ). The RCT performance varied between mono-and binary-metal sulfides, and metastable CuS had a high SO 3 conversion efficiency in the temperature range of 200−300 °C. Accordingly, the introduction of selenium (Se) lowered the electronegativity of the CuS host and enhanced its reducibility to SO 3 . Among the CuSe 1−x S x composites, CuSe 0.3 S 0.7 was the optimal RCT material and reached a SO 2 yield of 6.25 mmol/g in 120 min. The low-valence state of selenium (Se 2− /Se 1− ) exhibited a higher reduction activity for SO 3 than did S 2− /S 1− ; however, excessive Se doping degraded the SO 3 conversion owing to the re-oxidation of SO 2 by the generated SeO 3 2− . The density functional theory calculations verified the stronger SO 3 adsorption performance (E ads = −2.76 eV) and lower S−O bond breaking energy (E a = 1.34 eV) over CuSe 0.3 S 0.7 compared to those over CuS and CuSe. Thus, CuSe 1−x S x can serve as a model material and the RCT strategy can make use of field temperature conditions in nonferrous smelters for SO 3 emission control.

Temperature-Dependent Selection of Reaction Pathways, Reactive Species, and Products during Postsynthetic Selenization of Copper Sulfide Nanoparticles

“…15,18,19 These copper chalcogenides have been studied as solid electrolytes for Li + batteries, 20,21 thermoelectrics, 22,23 photothermal agents, 24 NIR plasmonics, 25 and for pollutant reduction. 26,27 The phase-selective synthesis of Cu 2−x S 28,29 and Cu 2−x Se 30−32 nanoparticles has been studied in detail. Cu 2−x (S,Se) particles, which have mixed sulfur and selenium as a solid solution rather than as a phase-segregated heterostructure, have been made through several routes, including direct synthesis of hexagonal and cubic alloys, 20,33 cation exchange of Cd(S,Se), 34 and oxidation of core/shell Cu 2−x Se/Cu 2−x S particles.…”

“…An array of Cu 2– x S–Cu 2– x Se nanoheterostructures have been created through cation exchange of CdS–CdSe structures obtained by such seeded growth including platelets, dot-in-rod structures where rods grow from wurtzite seed faces, and branched structures where arms grow from zinc blende seeds. , The system here provides new geometries that do not require growth of the overall particle size, including a nanorhombus structure with largely exposed heterojunctions. The Cu 2– x S–Cu 2– x Se nanoparticle system has received considerable attention for their promising properties and as useful starting materials for cation exchange. ,, These copper chalcogenides have been studied as solid electrolytes for Li + batteries, , thermoelectrics, , photothermal agents, NIR plasmonics, and for pollutant reduction. , The phase-selective synthesis of Cu 2– x S , and Cu 2– x Se − nanoparticles has been studied in detail. Cu 2– x (S,Se) particles, which have mixed sulfur and selenium as a solid solution rather than as a phase-segregated heterostructure, have been made through several routes, including direct synthesis of hexagonal and cubic alloys, , cation exchange of Cd­(S,Se), and oxidation of core/shell Cu 2– x Se/Cu 2– x S particles .…”

Study on the Efficiency of Fine Particle Removal in a Single-Tower Dual-Cycle Desulfurization Process Utilizing Heterogeneous Condensation

“…The removal efficiency can exceed 99.9% for particles larger than 10 µm, but it is relatively low for particles smaller than 2.5 µm [9][10][11]. Although wet desulfurization systems have relatively high efficiency in removing sulfur dioxide, they also generate secondary pollution, such as sulfur trioxide [12][13][14]. Additionally, while the wet desulfurization system has some impact on removing fine particles, the removal efficiency for smaller particles is very low due to the Greenfield Gap effect [15,16].…”