Insight into the Transformation Behaviors of Dioxins from Sintering Flue Gas in the Cyclic Thermal Regeneration by the V2O5/AC Catalyst-sorbent

Dioxins in the sintering flue gas are usually removed through integrated elimination technologies by carbonaceous catalysts. However, the regeneration of the used catalyst is poorly investigated, leading to the risk of leakage of dioxins. Herein, the influences of cyclic regenerations on the dioxin removal performance of a catalyst (V₂O₅/AC) were investigated systematically with dibenzofuran (DBF) as a model pollutant. It was demonstrated that the adsorption capacity and oxidation activity of catalysts significantly declined after several regeneration cycles due to the decreasing external specific surface area and V⁵⁺, respectively. Compared with 79.12% DBF directly emitted from a regenerator during N₂ regeneration, the emission of DBF was only 29.93% with the modification of the regeneration process through O₂ addition and temperature adjustment. The possible regenerated products were also analyzed to disclose the transformation behaviors of DBF. The regeneration mechanisms of DBF followed the transformation pathway of dibenzofuranol, benzofuran, anhydride species, and ultimately to CO₂ and H₂O. Moreover, the accumulated heavy aromatics on the surface could be decomposed by introducing O₂. This research provides a comprehensive understanding of dioxin transformation behavior and a theoretical basis for efficient control of dioxin removal in the whole integrated removal technologies.

Enhanced Photocatalytic hydrolysis performance of titanium disulfide nanosheets by chiral molecules loaded

The photoelectrochemical (PEC) water decomposition is a promising method to produce hydrogen from water. In order to improve the water decomposition efficiency of the PEC process, it is necessary to inhibit the generation of H 2 O 2  byproducts and reduce the overpotential required by cheap catalysts and a high current density. Studies have shown that coating the electrode with chiral molecules or chiral films can increase the hydrogen production and reduce the generation of H 2 O 2  byproducts. This is interpreted as the result of a chiral induced spin selectivity (CISS) effect, which induces a spin correlation between the electrons that are transferred to the anode. Here, we report the adsorption of chiral molecules onto titanium disulfide nanosheets. Firstly, titanium disulfide nanosheets were synthesized via thermal injection and then dispersed through ultrasonic crushing. This strategy combines the CISS effect with the plasma effect caused by the narrow bandgap of two-dimensional sulfur compounds to promote the PEC water decomposition with a high current density.

Insight into the enhancing activity and stability of Ce modified V2O5/AC during cyclic desulfurization-regeneration-denitrification

Cyclic desulfurization-regeneration-denitrification over carbon-based catalysts is a promising technology for SO₂ and NOx simultaneous elimination in steel industry. Regeneration is imperative to the long-term operation of the process, while the research is limited. In this work, Ce modified V₂O₅/AC catalyst (CeVOx/AC) with higher desulfurization and denitrification activity was prepared and the effect of cyclic regeneration was investigated. Results illustrated that the desulfurization and denitrification activity of CeVOx/AC gradually improved with increasing the regeneration cycles at the optimum regeneration temperature of 470 °C in N₂. The increasing Ce³⁺, V⁵⁺ and oxygen vacancies, enhanced surface acidity and improved redox ability contributed to the catalytic activity of regenerated catalysts. For desulfurization, more SO₂ transformed into H₂SO₄ rather than to metal sulfates after cyclic regeneration. For denitrification, the improved redox ability accelerated the oxidation of NO to active NO₂, bridged nitrites and nitrates, and the enhanced acidity facilitated the NH₃ adsorption, further generating more -NH₂ and promoting the SCR activity of regenerated samples. The CeVOx/AC with good activity and regenerative stability shows great application potential in steel industry for the simultaneous SO₂ and NOx removal.