SO2 reactivity on the MgO and CaO surfaces: A CW-EPR study of oxo-sulphur radical anions

Livraghi, Stefano; Paganini, Maria Cristina; Giamello, Elio

doi:10.1016/j.molcata.2010.02.012

Cited by 16 publications

(11 citation statements)

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“…5−11 MgO also serves as a catalyst itself, and there have been numerous experimental and computational studies of its properties for a range of reactions including oxidation and of its photochemical behavior. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] n clusters are models of such supporting materials and could also serve as nanosize containers for catalytic reactions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In addition, MgO is the only engineered barrier material approved for emplacement in the Waste Isolation Pilot Plant (WIPP) in the U.S . MgO has been used as a support for metal and bimetallic clusters for catalytic processes. − MgO also serves as a catalyst itself, and there have been numerous experimental and computational studies of its properties for a range of reactions including oxidation and of its photochemical behavior. − (MgO) n clusters are models of such supporting materials and could also serve as nanosize containers for catalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

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Structures and Stabilities of (MgO)_n Nanoclusters

2014

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Global minima for (MgO)n structures were optimized using a tree growth-hybrid genetic algorithm in conjunction with MNDO/MNDO/d semiempirical molecular orbital calculations followed by density functional theory geometry optimizations with the B3LYP functional. New lowest energy isomers were found for a number of (MgO)n clusters. The most stable isomers for (MgO)n (n > 3) are 3-dimensional. For n < 20, hexagonal tubular (MgO)n structures are more favored in energy than the cubic structures. The cubic structures and their variations dominate after n = 20. For the cubic isomers, increasing the size of the cluster in any dimension improves the stability. The effectiveness of increasing the size of the cluster in a specific dimension to improve stability diminishes as the size in that dimension increases. For cubic structures of the same size, the most compact cubic structure is expected to be the more stable cubic structure. The average Mg-O bond distance and coordination number both increase as n increases. The calculated average Mg-O bond distance is 2.055 Å at n = 40, slightly smaller than the bulk value of 2.104 Å. The average coordination number is predicted to be 4.6 for the lowest energy (MgO)40 as compared to the bulk value of 6. As n increases, the normalized clustering energy ΔE(n) for the (MgO)n increases and the slope of the ΔE(n) vs n curve decreases. The value of ΔE(40) is predicted to be 150 kcal/mol, as compared to the bulk value ΔE(∞) = 176 kcal/mol. The electronic properties of the clusters are presented and the reactive sites are predicted to be at the corners.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structures and Stabilities of (MgO)_n Nanoclusters

2014

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“…Several processes have been proposed and developed to remove SO 2 from various exhausts and implementation of more stringent regulations for the control of environmental pollution has spurred research on more efficient desulfurization processes, for example, capture of SO 2 by calcium‐based sorbents such as limestone and dolomite . Furthermore, carbide slag constitutes another industrial residue from the production of C 2 H 2 and PVC by calcium carbide hydrolysis .…”

Section: Introductionmentioning

confidence: 99%

Dealkalization of Red Mud by Carbide Slag and Flue Gas

Wang

Zhang

Liu

et al. 2018

CLEAN Soil Air Water

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Red mud and carbide slag which are industrial waste materials from alumina and chlor‐alkali plants pose environmental risks due to the large production volume. However, reutilization has been limited due to their composition and structure and the large alkali concentration in red mud has hampered utilization of red mud. At the same time, flue gas produced during the process of coal firing is a major environmental threat causing greenhouse effects and fog haze. In this work, alkalis (Na2O) in red mud were released by the alkali and acid methods and carbide slags and flue gas were utilized to remove alkalis from red mud. The effects of the reaction time, temperature, and solid‐to‐liquid ratio on dealkalization of red mud by carbide slag were studied. Flame absorption and X‐ray diffraction were employed to monitor the changes in the red mud before and after dealkalization. Under the optimal conditions, the residual Na2O amount in the red mud after dealkalization using the carbide slag diminished to less than 3 wt%, whereas that of Na2O dropped to less than 2 wt% using flue gas. The pH of the suspension is determined by the acid method. The hydroxysodalite (Na8Al6Si6O24(OH)2) structure in the initial red mud was destroyed and soluble sodium salts formed in the suspension can be easily replaced by carbide slag or flue gas reducing Na2O.

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“…36,[39][40] Note that these signals are very different from SO2radical has a typical sharp signal with g values on 2.008-2.005. [41][42] Figure 4. X-band EPR of Fe III TPPCl (green), Fe II TPP (blue) and the product of Fe II TPP reaction with SO2 (green) collected at 77K.…”

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confidence: 99%

Reduction of Sulfur Dioxide to Sulfur Monoxide by Ferrous Porphyrin

Bhattacharya

Nath

Ghatak

et al. 2021

Preprint

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Reduction of SO2 to fixed forms of sulfur can address the growing concerns regarding its detrimental effect on health and environment as well as enable its valorization into valuable chemicals. While the coordination of SO2 to transition metals are documented, its reduction using molecular catalysts has remained elusive. Alternatively, the naturally occurring heme enzyme sulfite reductase is known to reduce SO2 to H2S and is an integral part of the global sulfur cycle. However, its action is not yet mimicked in artificial systems outside of the protein matrix even after several decades of its structural elucidation. Here reduction of SO2 by iron (II) porphyrin, a synthetic analogue of heme, is demonstrated. A combination of spectroscopic and analytical methods indicates that SO2 is reduced by 2e -/2H + by Fe II TPP to form an intermediate [Fe III -SO] + species which releases SO. The SO obtained from the chemical reduction of SO2 could be valorized in the form of a Diels-Alder adduct of butadiene resulting in an organic sulfoxide.

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SO2 reactivity on the MgO and CaO surfaces: A CW-EPR study of oxo-sulphur radical anions

Cited by 16 publications

References 50 publications

Structures and Stabilities of (MgO)_n Nanoclusters

Structures and Stabilities of (MgO)_n Nanoclusters

Dealkalization of Red Mud by Carbide Slag and Flue Gas

Reduction of Sulfur Dioxide to Sulfur Monoxide by Ferrous Porphyrin

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SO2 reactivity on the MgO and CaO surfaces: A CW-EPR study of oxo-sulphur radical anions

Cited by 16 publications

References 50 publications

Structures and Stabilities of (MgO)n Nanoclusters

Structures and Stabilities of (MgO)n Nanoclusters

Dealkalization of Red Mud by Carbide Slag and Flue Gas

Reduction of Sulfur Dioxide to Sulfur Monoxide by Ferrous Porphyrin

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Product

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Structures and Stabilities of (MgO)_n Nanoclusters

Structures and Stabilities of (MgO)_n Nanoclusters