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Sulfur dioxide (SO2) emission has become a crucial problem, especially in developing countries since it is one of the main reasons for the formation of acid precipitation and the secondary formation of fine particulate matter (PM2.5). Wet magnesia desulfurization stands out as a widely used practical approach for the control of SO2 due to its high removal efficiency, low operating cost and potential valuable by-products. However, the effluent of magnesium sulfite (main by-product) can reemit SO2 and cause water pollution. Thus, it is important, but challenging, to enhance the oxidation rate to improve the utilization of MgSO4 for sustainable resources and meanwhile downsize the absorbing tower. Herein, we report a series of graphitic carbon nitride (g-C3N4)-assembled transition metal catalysts (M–C3N4) for the first time via a facile and environmentally friendly synthetic route as a new generation of catalysts for the oxidation of magnesium sulfite. We have performed both theoretical evaluation and deep experimental validation of the series of M–C3N4 materials, and in particular, the cobalt–C3N4 material since it possesses the best catalytic activity reported to date, which is comparable to that of aqueous precious metal benchmarks but only with a 2.4 wt% cobalt loading. Additionally, the ability to recycle the Co–C3N4 complex is investigated to facilitate its practical application. This fabrication method is expected to provide a new concept for the construction of multifunctional nanocomposites for a large variety of industrially relevant desulfurization applications. [ABSTRACT FROM AUTHOR]

Defect engineering is considered as a flexible and effective mean to improve the performance of Fenton-like reactions. Herein, a simple method is employed to synthesize Co 3 O 4 catalysts with Co-O vacancy pairs (V P ) for peroxymonosulfate (PMS) activation. Multi-scaled characterization, experimental, and simulation results jointly revealed that the cation vacancies-V Co contributed to enhanced conductivity and anion vacancies-V O provided a new active center for the 1 O 2 generation. Co 3 O 4 -V P can optimize the O 2p and Co 3d bands with the strong assistance of synergistic double vacancies to reduce the reaction energy barrier of the "PMS → Co(IV) = O → 1 O 2 " pathway, ultimately triggering the stable transition of mechanism. Co 3 O 4 -V P catalysts with radical-nonradical collaborative mechanism achieve the synchronous improvement of activity and stability, and have good environmental robustness to favor water decontamination applications. This result highlights the possibility of utilizing anion and cation vacancy engineering strategies to rational design Co 3 O 4 -based materials widely used in catalytic reactions., (© 2024 Wiley‐VCH GmbH.)

High energy duty restricts the application of amine-based absorption in CO 2 capture and limits the achievement of carbon neutrality. Although regenerating the amine solvent with solid acid catalysts can increase energy efficiency, inactivation of the catalyst must be addressed. Here, we report a robust metal-organic framework (MOF)-derived hybrid solid acid catalyst (SO 4 2- /ZIF-67-C@TiO 2 ) with improved acidity for promoting amine regeneration. The TiO 2 coating effectively prevented the active components stripping from the surface of the catalyst, thus prolonging its lifespan. The well-protected Co-N x sites and protonated groups introduced onto the TiO 2 surface increased the amount and rate of CO 2 desorption by more than 64.5 and 153%, respectively. Consequently, the energy consumption decreased by approximately 36%. The catalyzed N-C bond rupture and proton transfer mechanisms are proposed. This work provides an effective protection strategy for robust acid catalysts, thus advancing the CO 2 capture with less energy duty.