Design for precise desulfurization

Generally, wet methods are used to remove inorganic sulfur, while dry methods are used to remove organic sulfur.

It seems that there isn’t much relevant information available at the moment, and I exactly need such information. I hope some colleagues can offer some guidance.

There are several methods: 1: Ultrasonic irradiation – The removal of organic sulfur from coal under ultrasonic irradiation in a methanol solvent. The results show that the removal rate of organic sulfur in coal increases with the increase in the amount of methyl iodide used and the duration of ultrasonic irradiation. Based on the analysis results from the infrared spectrometer and gas chromatography/mass spectrometry, the organic sulfur compounds removed included thioethers and disulfides. 2: Microbial removal. In recent years, a new two-stage microbial desulfurization process has been proposed abroad. First, autotrophic microorganisms that use CO2 as a carbon source (such as Thiobacillus ferrooxidans) are used to remove sulfur from pyrite. Then, acid treatment is employed to dissolve the carbonates and certain metal ions that interfere with biological desulfurization; this step also increases the surface area of the coal, allowing the organic components to be exposed to the greatest extent possible. Finally, exotic microorganisms obtained from outside are used to remove the organic sulfur, thereby achieving optimal results. The methods for determining organic sulfur are also not perfect; **the standard procedures are very complicated, and to this day it is still not possible to accurately determine the types of organic sulfur, as well as the specific contents and chemical properties of its various components. All of these factors objectively hinder the development of methods for removing organic sulfur. Currently, commonly used methods include electron microprobe (EMP), transmission electron microscopy (TEM), X-ray absorption fine structure spectroscopy (XAFS), and X-ray photoelectron spectroscopy (XPS) to obtain important information on the composition and proportions of organic sulfur in coal. 3: Thermal desulfurization in a fluidized bed under an oxidizing atmosphere: With oxygen volume fractions of 3.0%, 5.6%, and 8.7%, and a pyrolysis temperature ranging from 400 °C to 800 °C, with a pyrolysis residence time of 30 minutes, thermal desulfurization experiments were conducted in a fluidized bed reactor. The results showed that Yanzhou coal achieved the best desulfurization efficiency at 3.0% O2 and 600 °C, reaching 70%; at this condition, all of the sulfur present as pyrite was removed, and more than 60% of the organic sulfur was also eliminated. Under the same temperature but in an inert atmosphere, the removal rates for total sulfur and organic sulfur were 25% and 15%, respectively. In an oxidizing atmosphere, the sulfur removed mainly ended up in the tar; as the oxygen volume fraction increased, the yield of semi-coke decreased rapidly, and the degree of this decrease was greater than the increase in the desulfurization rate. Therefore, too high an oxygen volume fraction leads to the breaking of C-C bonds as well as the selective breaking of C-S bonds. 4: Electrochemical removal of organic sulfur in coal in an alkaline medium: Using high-sulfur coal as raw material, its inorganic sulfur was removed through chemical methods, after which this coal sample was used for electrochemical studies under alkaline conditions to investigate the mechanisms of electrochemical desulfurization of organic sulfur in coal. The effects of key factors such as electrolytic current, coal slurry concentration, and NaOH concentration on the desulfurization rate of organic sulfur were discussed, and optimal conditions for electrochemical desulfurization were determined: a NaOH concentration of 4.0 mol/L, a coal slurry concentration of 0.04 g/mL, a reaction temperature of 70 °C, an electric current intensity of 1.0 A, and an electrolysis time of 5 hours. These conditions yielded a good desulfurization rate of 32.50% for organic sulfur.