Molecular Complexes of Sulphur Dioxide With N,o-Containing Organic Bases (Review)

Khoma, R. E.; Еннан, А. А.

doi:10.18524/2304-0947.2016.3(59).79510

Cited by 1 publication

(3 citation statements)

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“…Increasing the basic nature of carbon through the inclusion of basic forms of nitrogen turned out to be a positive factor affecting the absorption of SO 2 and its oxidation to sulfuric acid [31, [59][60][61][62][63][64]. Obviously, the above-mentioned first adsorption energy (~50 kJ/mol) in this case is determined not only by van der Waals interactions (dipole-dipole interactions and dispersion forces), but also by π-dative S←N or S←O bonding (∆HS←N = 20-90kJ/mol; ∆HS←O = 10-55 kJ/mol [65]) with the formation of charge transfer complexes with Lewis bases and H-bonding, similarly to [65].…”

Section: Effect Of Chemical Activator On Ac Propertiesmentioning

confidence: 99%

“…In the process of obtaining AC, the authors of [62,66] carried out N-doping of various carbon raw materials (sub-bituminous coal, lignite; AC fabric based on viscose) by activation with steam enriched with ammonia or its derivatives ((NH 4 ) 2 CO 3 , H 2 NNH 2 , NH 2 OH, H 2 NC (O)NH 2 ; this leads to the formation of various N-containing groups (amides, imides, lactams, nitriles, pyrroles, pyridines, etc.) -Lewis basic centers, which favors S←O and S←N bonding, similarly to [65]. AC with a high N content was obtained [31] by the carbonization of macroporous vinyl pyridine polymers, which are themselves chemisorbents of acid gases, in particular SO 2 [67].…”

Section: Effect Of Chemical Activator On Ac Propertiesmentioning

confidence: 99%

“…The authors of [43] indicate an increase in SO 2 adsorption efficiency as a result of the N-doping of the carbon surface due to increased physical adsorption. For a pristine carbon surface after N-doping, SO 2 physical adsorption mainly occurs on the basal plane through van der Waals (similarly to [68,69]) or π-dative interactions (similarly to [65,70]). N-doping redistributes electrons on carbon surfaces, thereby changing not only the intensity but also the types of interactions involved; quaternary N atoms contribute to SO 2 adsorption, mainly due to the enhancement of "van der Waals" interactions between the basal plane and SO 2 [43].…”

Section: Effect Of Chemical Activator On Ac Propertiesmentioning

confidence: 99%

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Impregnated Activated Carbon Materials for Respiratory Purpose. Chemisorption of Sulfur Dioxide

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Vodzinskii,

Klimov

2023

Ukr. Chem. Journ.

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The review is devoted to the use of impregnated activated carbon materials as chemisorbents of sulfur (IV) oxide. General methods for obtaining ordinary activated carbon, preparation of raw materials, their chemical activation with alkalis and acids followed by heat treatment (carbonization) in an inert environment or in the presence of a gaseous oxidizer, the role of acid-base and redox catalysts in this process are considered. The influence of the chemical composition of the activated carbon surface, the presence of functional groups, and their acid-base properties, as well as the products of surface reactions on the peculiarities of sulfur (IV) oxide adsorption is analyzed from the point of view of SO2 removal efficiency and the possibility of SO2 regeneration. An important role in these processes is played by the pore size, the possibility of co-adsorption of water, and the presence of an oxidant. The nature of adsorbent-adsorbate interactions on the surface of activated carbon, their energy, in particular, the contribution of so-called "physical" adsorption, van der Waals forces, hydrogen bonding, and the influence of surface functional groups are discussed. The activation of carbon raw materials with nitrogen-containing compounds leads to the N-doping of the surface, which increases the efficiency of SO2 adsorption, facilitating not only van der Waals and electrostatic interactions, but also S←N binding. The influence of oxygen and oxygen-containing functional groups on SO2 adsorption is also discussed. To obtain impregnated activated carbon for SO2 absorption, the original activated carbon of the required quality is impregnated with solutions of inorganic and organic compounds that remain on the inner surface of the activated carbon after drying. Impregnation blocks partly the porosity of activated carbon, but makes it more capable of chemical adsorption. Chemisorption, in which certain chemical bonds are formed between the surface of the activated carbon and the compound being adsorbed, is more selective than physical adsorption, where the size of molecules is critical for an effective capture process. It can be noted that unlike inorganic alkalis, which spoil the porous structure of activated carbon, treatment with a solution of ammonia or organic N-containing bases promotes SO2 absorption. A special place in gas purification is occupied by activated carbon impregnated with ionic liquids, non-aqueous solvents being used for impregnation. A separate issue of the chemisorption of sulfur (IV) oxide by samples of impregnated activated carbon based on d-metals will be discussed in detail below.

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