Mechanism of the desulfurization route of the reduction of SO2 on carbons. Dimerization of Disulfur and Tetrasulfur

IF 1.9 4区 化学 Q2 CHEMISTRY, ORGANIC Journal of Physical Organic Chemistry Pub Date : 2024-04-23 DOI:10.1002/poc.4610
Eduardo Humeres, Marília Isabel Tarnowski Correia, Nito Angelo Debacher, Regina de F. P. M. Moreira
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Abstract

The desulfurization of carbons modified with SO2 was studied as a dispersion in boiling cyclohexane (81°C) using activated carbon (mAC) and graphene oxide (mGO), modified by SO2. The steady-state species in the carbon matrix after the catalytic reduction of SO2 was considered a trisulfane. For mAC, there was a burst of a sulfur species identified as S2 by UV spectrum with a maximum at 217 nm (εM at 217 nm = 2.56 × 103) that showed a second-order decay of absorbance with k S 2 = 47.29 M-1·sec-1 ( ΔG 354 = 18.1 kcal·mol-1). The product was postulated to be S4. No other consecutive reaction was observed because of the possible adsorption of S4 in the carbon matrix. The desulfurization of mGO was shown by XPS and the kinetics were a second-order decay up to 16 min ( k S 2 = 18.41 M-1·sec-1; ΔG 354 = 18.8 kcal·mol-1) followed by a second-order increase of absorbance with k S 4 = 3.84 M-1·sec-1 ( ΔG 354 = 19.9), where the product showed a double maximum at 260-285 nm typical of S8. These results are consistent with a mechanism of consecutive thermodynamically favorable dimerizations of S2 and S4 and with the desulfurization mechanism that has been previously postulated.

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碳上还原二氧化硫的脱硫途径的机理。二硫和四硫的二聚反应
利用经二氧化硫改性的活性炭(mAC)和氧化石墨烯(mGO),研究了经二氧化硫改性的碳在沸腾的环己烷(81°C)中分散的脱硫过程。在催化还原 SO2 后,碳基质中的稳态物质被认为是三硫烷。就 mAC 而言,在 217 纳米波长(217 纳米波长处的εM = 2.56 × 103)处出现了紫外光谱最大值(= 47.29 M-1-sec-1(= 18.1 千卡-摩尔-1))的硫物种猝灭,其吸光度呈二阶衰减(= 47.29 M-1-sec-1 = 18.1 千卡-摩尔-1)。推测产物为 S4。由于碳基质中可能吸附了 S4,因此没有观察到其他连续反应。XPS 显示了 mGO 的脱硫过程,其动力学是在 16 分钟内出现二阶衰减(18.41 M-1-sec-1;= 18.8 kcal-mol-1),随后吸光度出现二阶上升(= 3.84 M-1-sec-1;= 19.9),产物在 260-285 纳米波长处显示出典型的 S8 双最大值。这些结果与 S2 和 S4 连续发生热力学上有利的二聚化机理以及之前推测的脱硫机理相一致。
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来源期刊
CiteScore
3.60
自引率
11.10%
发文量
161
审稿时长
2.3 months
期刊介绍: The Journal of Physical Organic Chemistry is the foremost international journal devoted to the relationship between molecular structure and chemical reactivity in organic systems. It publishes Research Articles, Reviews and Mini Reviews based on research striving to understand the principles governing chemical structures in relation to activity and transformation with physical and mathematical rigor, using results derived from experimental and computational methods. Physical Organic Chemistry is a central and fundamental field with multiple applications in fields such as molecular recognition, supramolecular chemistry, catalysis, photochemistry, biological and material sciences, nanotechnology and surface science.
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