Abstract

Ozone is a strong oxidizer and sulfur dioxide is a precursor to acid rain, both are air pollutants that can damage the respiratory tissues of animals and plants making them hazardous to the environment. They are isoelectronic valence O = X = O (X = S, O) molecules and their mechanism of reduction on carbons is similar. The solid–gas kinetics were studied in a flow system with a tubular reactor under differential and steady state conditions. Initial rates and product distribution were used to determine the stoichiometry of the reaction. The reduction of XO₂ on carbons proceeds through a common primary mechanism with oxidized and reduced intermediates. The reactivity of the intermediates that were inserted on carbons (graphite, activated carbon, graphene oxide) modified by SO₂ is selective with respect to aminolysis and thiolysis. A theoretical study of the chemisorption of SO₂ on dehydrogenated pyrene as graphite active site model showed that at 900 °C the chemisorption occurs mainly on the diradical zigzag edge. Computational quantum chemistry calculations were carried out for the reduction of SO₂ on graphite to produce elemental sulfur and CO₂ using tetradehydrogenated-benzo[α]anthracene (TBA) as model. The mechanisms of the decarboxylation and sulfur transport steps were postulated. Ozonation of graphite showed that the 1,2,3-trioxolane decomposes to an oxyrene, eliminating O₂. Both reactions, the SO₂ and O₃ with graphite, have the same experimental free energy of activation for the decarboxylation reaction. The results show that for SO₂ the desulfurization has a much lower energetic demand than the decarboxylation route raising the important possibility of using the reaction of reduction of SO₂ on carbons to reduce the acid rain, producing elemental sulfur as the main product, without increasing the greenhouse effect due to the formation of CO₂.

Graphic Abstract

中文翻译：

---

固-气反应机理：减少碳上的空气污染物

摘要

臭氧是强氧化剂，二氧化硫是酸雨的前兆，两者都是空气污染物，会损害动植物的呼吸组织，从而危害环境。它们是等价电子O = X = O（X = S，O）分子，其碳还原机理相似。在带有管式反应器的流动系统中，在微分和稳态条件下研究了固-气动力学。初始速率和产物分布用于确定反应的化学计量。碳上XO ₂的还原是通过具有氧化和还原中间体的常见主要机理进行的。插入经SO ₂改性的碳（石墨，活性炭，氧化石墨烯）上的中间体的反应性对于氨解和硫解是选择性的。对SO ₂在脱氢pyr上作为石墨活性位点模型的化学吸附的理论研究表明，在900°C时，化学吸附主要发生在双自由基之字形边缘。以四脱氢苯并[α]蒽（TBA）为模型，对石墨上的SO ₂还原生成元素硫和CO ₂进行了计算量子化学计算。推测了脱羧和硫转移步骤的机理。石墨的臭氧化表明1,2,3-三氧戊环分解为氧化an，消除了O ₂。两种反应，SO ₂和O ₃与石墨的脱羧反应具有相同的实验活化自由能。结果表明，对于SO _2而言，脱硫的能量需求比脱羧途径低得多，这增加了利用SO ₂还原反应在碳上减少酸雨，产生元素硫为主要产物而不增加的重要可能性。由于形成CO ₂而产生的温室效应。

图形摘要