Reduction of Sulfur Dioxide on Carbons Catalyzed by Salts

Eduardo Humeres,Regina F.P.M Moreira,Wido Schreiner,Maria Da Gloria B Peruch

doi:10.3390/i6010130

Eduardo Humeres, Regina F.P.M Moreira + Show 2 more

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https://doi.org/10.3390/i6010130

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Abstract

Abstract. The reduction of SO 2 on different carbons in the presence of the nitrates and sulfides of sodium, potassium and calcium and potassium polysulfides was studied. The presence of salts increased the initial rate 2-5 fold for all of them and did not change the product distribution. The catalysis was not determined by the cation and there was no difference in the catalytic reactivity between nitrates and sulfides. The sulfur content of the activated carbon increased during the reaction on account of the stable reactive intermediates in the reduction of SO 2 . In the presence of NaNO 3 or Na 2 S, the amount of sulfur incorporated was in the molar ratio Na:S = 3 ± 0.3, and the XPS spectra of the residual carbon showed an increase of ca. 9% of the non-oxidized form of sulfur in the intermediates. In the absence of salt, it is proposed that after the adsorption of SO 2 on the carbon, a 1,3,2-dioxathiolane or 1,2-oxathietene 2-oxide are formed and that decompose to produce CO 2 and atomic sulfur. The non-oxidized sulfur intermediate would be an episulfide

Highlights

The reduction of SO2 on carbons has been intensively studied because sulfur and nitrogen oxides are considered among the worst atmospheric pollutants and precursors of acid rain [1]
The reactivity of graphite in the presence of sodium, potassium and calcium salts increased by a factor of 2-5 and the maximum effect was observed for K2S (Table 2)
There were no important differences between the catalytic effects of nitrates and sulfides on the reduction of SO2 on carbons, and this similarity was observed for polysulfides

Summary

Introduction

The reduction of SO2 on carbons has been intensively studied because sulfur and nitrogen oxides are considered among the worst atmospheric pollutants and precursors of acid rain [1]. The reduction of SO2 on activated carbon in the absence of salt showed that the sulfur content of the carbon increased until a constant value when the reaction reached the steady-state condition.

Results

Conclusion