Se‐catalyzed process of sodium bisulfite disproportionation

Abstract

AbstractBACKGROUNDSO2 is an important gaseous pollutant that seriously affects the environment and human health. The most common method for SO2 removal is absorption by NaOH solution and then forming HSO3−. Since generation of high‐value products and reduction of alkali consumption are important for the economy and practical application, selenium‐catalyzed HSO3− disproportionation was developed in this study.RESULTSSelenium decreased the reaction temperature of HSO3− disproportionation from >433 K to 343 K. The effects of HSO3− concentration, temperature, selenium dosage, and stirring intensity were investigated. Selenium could be used at least five times with stable catalytic performance, indicating satisfactory reusability. More importantly, a catalytic mechanism was proposed using dynamic light scattering, differential scanning calorimetry and UV‐visible transmittance spectrophotometry. Results showed that selenium‐catalyzed HSO3− disproportionation experienced a solid–liquid–solid phase transformation process. During this process, SeSO32− and HSe− were identified as the intermediates. Furthermore, products, i.e. sulfur and sodium bisulfate, were characterized to demonstrate their structure and composition.CONCLUSIONSelenium was an efficient catalyst for HSO3− disproportionation. This catalytic process offered the advantages of less consumption of alkali and production of high‐valuable products, and thus was a potential alternative to other technology for SO2 removal in practical applications. © 2015 Society of Chemical Industry