Monitoring of the Chemical Species in a Liquid-Phase Claus Reaction

Rouquette, Charlotte; Digne, Mathieu; Renaudot, L.; Grandjean, Jean; Ballaguet, Jean-Pierre

doi:10.1021/ef900152x

Cited by 5 publications

(7 citation statements)

References 25 publications

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“…has shown that the measured room-temperature spectra of solid K 2 S n (1 ≤ n ≤ 6) are distinct . Lengthening of the S n 2– chains should lead to salient differences between the chains in the melt . Our room-temperature Raman spectra for K 2 S 3 and K 2 S 5 are shown in Figure .…”

Section: Resultsmentioning

confidence: 79%

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Understanding Fluxes as Media for Directed Synthesis: In Situ Local Structure of Molten Potassium Polysulfides

et al. 2012

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Rational exploratory synthesis of new materials requires routes to discover novel phases and systematic methods to tailor their structures and properties. Synthetic reactions in molten fluxes have proven to be an excellent route to new inorganic materials because they promote diffusion and can serve as an additional reactant, but little is known about the mechanisms of compound formation, crystal precipitation, or behavior of fluxes themselves at conditions relevant to synthesis. In this study we examine the properties of a salt flux system that has proven extremely fertile for growth of new materials: the potassium polysulfides spanning K(2)S(3) and K(2)S(5), which melt between 302 and 206 °C. We present in situ Raman spectroscopy of melts between K(2)S(3) and K(2)S(5) and find strong coupling between n in K(2)S(n) and the molten local structure, implying that the S(n)(2-) chains in the crystalline state are mirrored in the melt. In any reactive flux system, K(2)S(n) included, a signature of changing species in the melt implies that their evolution during a reaction can be characterized and eventually controlled for selective formation of compounds. We use in situ X-ray total scattering to obtain the pair distribution function of molten K(2)S(5) and model the length of S(n)(2-) chains in the melt using reverse Monte Carlo simulations. Combining in situ Raman and total scattering provides a path to understanding the behavior of reactive media and should be broadly applied for more informed, targeted synthesis of compounds in a wide variety of inorganic fluxes.

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Section: Resultsmentioning

confidence: 79%

“…There is no consensus on suitable methods to characterize these systems at conditions relevant to crystal growth. Attempts to model the stability of polyanionic species have been limited to the gas phase, , but these isolated molecules do not share the structure or stability of their counterparts in liquid salts…”

Section: Introductionmentioning

confidence: 99%

Understanding Fluxes as Media for Directed Synthesis: In Situ Local Structure of Molten Potassium Polysulfides

et al. 2012

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“…As is known, the structure of SeSO 3 2− is similar to that of S 2 O 3 2− . Many researchers proposed that S 2 O 3 2− released HS − under acid conditions. Similarly, many studies suggested that HSe − could be released from the hydrolytic decomposition of SeSO 3 2− in acidic media.…”

Section: Resultsmentioning

confidence: 99%

Se‐catalyzed process of sodium bisulfite disproportionation

Chai

Yang

Liu

et al. 2015

J of Chemical Tech & Biotech

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BACKGROUND: SO 2 is an important gaseous pollutant that seriously affects the environment and human health. The most common method for SO 2 removal is absorption by NaOH solution and then forming HSO 3 − . Since generation of high-value products and reduction of alkali consumption are important for the economy and practical application, selenium-catalyzed HSO 3 − disproportionation was developed in this study.RESULTS: Selenium decreased the reaction temperature of HSO 3 − disproportionation from >433 K to 343 K. The effects of HSO 3 − 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 HSO 3 − disproportionation experienced a solid-liquid-solid phase transformation process. During this process, SeSO 3 2− and HSe − were identified as the intermediates. Furthermore, products, i.e. sulfur and sodium bisulfate, were characterized to demonstrate their structure and composition. CONCLUSION: Selenium was an efficient catalyst for HSO 3− 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 SO 2 removal in practical applications. /jctb As shown in the inset graph, standard HSO 3 − had an obvious characteristic absorption peak at 230-350 nm. However, the peak at 235 nm decreased when reaction time was increased from 10 to

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“…Traditionally, this process is a gas–solid catalytic reaction, and the temperature must be maintained above the dew point of sulfur; otherwise, the solid sulfur will deposit on the surface of the catalysts . Form the point of kinetics, the activation energy of the gas–solid catalytic reaction is about 30 kJ/mol, which is much higher than that of the liquid-phase Claus reaction. , In recent years, with the study of liquid-phase Claus reaction, the high conversion rate of H 2 S under mild reaction conditions was realized, and the produced solid sulfur could be separated easily. − Wu et al , investigated various normal ILs and deep eutectic solvents (DESs, or called analogue ILs) as the medium for the Claus reaction, which could achieve a conversion rate up to 99% under 40 °C. It is noted that the ILs used in their study are normal ILs and can absorb a large amount of SO 2 only by physical interaction at a high concentration of SO 2 .…”

Section: Introductionmentioning

confidence: 99%

Efficient Regeneration of SO₂-Absorbed Functional Ionic Liquids with H₂S via the Liquid-Phase Claus Reaction

Zhang

Hou

Ren

et al. 2019

ACS Sustainable Chem. Eng.

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Functional ionic liquids (ILs), which have high absorption capacities of low-concentration SO2 through chemical interaction, have been widely studied. However, the absorbed SO2 in functional ILs is normally desorbed with high-temperature and steaming treatment, which is harmful to the stability of absorbents and causes high-energy consumption. In this work, functional ILs (monoethanolaminium lactate-[MEA]L, 1,1,3,3-tetramethylguanidinium lactate-[TMG]L, tetraethylammonium lactate-[N2222]L) mixed with ethylene glycol (EG) or H2O were used to capture low-concentration SO2, and then H2S was added to regenerate the absorbents via the liquid-phase Claus reaction. It was found that the reaction of H2S with SO2 in the absorbents proceeded fast and the absorbed SO2 was almost completely converted to solid sulfur (S8) under mild conditions without the addition of any catalysts. The effects of temperature, H2S initial pressure, and solvent on the Claus reaction in the functional ILs were investigated, and the optimal reaction conditions were obtained. The recycle experiments showed that the activity of the functional ILs for the Claus reaction was not decreased after being reused three times. The Claus reaction between H2S and SO2 in functional ILs provides a promising method for the efficient regeneration of functional ILs and SO2 resource utilization.

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Monitoring of the Chemical Species in a Liquid-Phase Claus Reaction

Cited by 5 publications

References 25 publications

Understanding Fluxes as Media for Directed Synthesis: In Situ Local Structure of Molten Potassium Polysulfides

Understanding Fluxes as Media for Directed Synthesis: In Situ Local Structure of Molten Potassium Polysulfides

Se‐catalyzed process of sodium bisulfite disproportionation

Efficient Regeneration of SO₂-Absorbed Functional Ionic Liquids with H₂S via the Liquid-Phase Claus Reaction

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Monitoring of the Chemical Species in a Liquid-Phase Claus Reaction

Cited by 5 publications

References 25 publications

Understanding Fluxes as Media for Directed Synthesis: In Situ Local Structure of Molten Potassium Polysulfides

Understanding Fluxes as Media for Directed Synthesis: In Situ Local Structure of Molten Potassium Polysulfides

Se‐catalyzed process of sodium bisulfite disproportionation

Efficient Regeneration of SO2-Absorbed Functional Ionic Liquids with H2S via the Liquid-Phase Claus Reaction

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Product

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Efficient Regeneration of SO₂-Absorbed Functional Ionic Liquids with H₂S via the Liquid-Phase Claus Reaction