Sulfamic Acid–Catalyzed Oxidation of Sulfides to Sulfoxides and Sulfones Using H2O2: Green and Chemoselective Method

Simultaneous removal of NOx and SO2 with H2O2 over silica sulfuric acid catalyst synthesized from fly ash

Considering that the utilization of fly ash in the removal of flue gas pollutants not only provide a way of high value-added utilization of fly ash, but also greatly reduce the cost of removing flue gas pollutant, the synthesis of silica sulfuric acid catalyst from fly ash and its application in simultaneous removal of NOx and SO₂ with H₂O₂ were investigated in this work. Circulating fluidized bed boiler (CFB) fly ash and pulverized coal boiler (PC) fly ash were selected as raw material to prepare silica sulfuric acid catalyst by H₂SO₄ activation. PC fly ash was difficult to be activated by H₂SO₄ due to its dense structure, while CFB fly ash could be treated with H₂SO₄ to promote dealumination, thereby increasing the silica content. Moreover, the -SO₃H withdrawing groups were detected on the silica surface by XPS and Py-FTIR technologies, indicating the formation of silica sulfuric acid. Silica sulfuric acid showed higher activity in catalyzing the NO oxidation by H₂O₂, and a possible reaction mechanism was proposed. Combined with alkali absorption, 99% SO₂ and 92% NOx removal efficiencies can be achieved. The effects of activation conditions such as activation temperature, activation time and calcination temperature and removal experimental parameters such as H₂O₂ concentration, SO₂ concentration and simulated flue gas temperature on the catalytic performance were studied. Finally, the catalyst was not found to be deactivated for ten hours in the stability test.

Sulphur-containing nonaromatic polymers: clustering-triggered emission and luminescence regulation by oxidation

Sulphur-containing nonconventional luminophores with clustering-triggered emission characteristics are developed, whose emission is readily modulated through oxidation.

Metal-free chemoselective oxidation of sulfides to sulfoxides catalyzed by immobilized l-aspartic acid and l-glutamic acid in an aqueous phase at room temperature

Immobilized l-aspartic and l-glutamic acid were employed in the oxidation of sulfides, and 99% conversion and 97% selectivity were achieved.

pH-Dependence of the Aqueous Phase Room Temperature Brønsted Acid-Catalyzed Chemoselective Oxidation of Sulfides with H₂O₂

A pH-dependence of the Brønsted acid-catalyzed oxidation of sulfides to the corresponding sulfoxides with H₂O₂ is reported for the first time based on our systematic investigation of the catalytic performance of a series of Brønsted acids. For all of the Brønsted acids investigated, the catalytic performances do not depend on the catalyst loading (mol ratio of Brønsted acid to substrate), but rather depend on the pH value of the aqueous reaction solution. All of them can give more than 98% conversion and selectivity in their aqueous solution at pH 1.30, no matter how much the catalyst loading is and what the Brønsted acid is. This pH-dependence principle is a very novel perspective to understand the Brønsted-acid catalysis system compared with our common understanding of the subject.

Selective Oxidation of Sulfides to Sulfoxides Catalysed by Deep Eutectic Solvent with H2O2

A Brønsted acidic deep eutectic solvent based on choline chloride and p-toluenesulfonic acid (ChCl/ p-TsOH, 1:1) was prepared and utilised for the selective oxidation of sulfides with H2O2 as the oxidant. Broad substrate compatibility, good yields and selectivities, the reusability of the catalyst as well as the gram-scale synthesis are the major advantages of this protocol. Moreover, the use of ChCl/ p-TsOH, instead of neat p-TsOH, can greatly reduce the acid sewage especially in large-scale synthetic processes.