Desulfurizer

Desulfurizer - Names and Identifiers

Name	Desulfurizer
Synonyms	Desulfurizer

Desulfurizer - Physico-chemical Properties

Molecular Formula	2ZnCO3-3ZN(OH)2-2H2O
Use	Applications for methanol, Biol, ammonia synthesis, gas methanation and food grade carbon dioxide and other industries of fine desulfurization

Desulfurizer - Uses and synthesis methods

overview

Desulfurizers are agents that remove free sulfur or sulfur compounds from fuels, raw materials or other materials; in the control or treatment of pollutants, they mainly refer to agents that can remove sulfur oxides (including SO2 and SO3) from exhaust gas. Various basic compounds can be used as desulfurizers. The most common desulfurizer for removing sulfur dioxide from flue gas is cheap lime, limestone and alkaline solution prepared with calcareous agent. The desulfurizer can absorb most of the sulfur dioxide in the flue gas without discharging with the gas. It can be absorbed by lime water spray, or solid lime powder can be directly mixed into pulverized coal or sprayed into the combustion furnace to fix the sulfide in the fuel slag. Chemical plants, smelters, etc. often use sodium carbonate, alkaline aluminum sulfate and other solutions as desulfurizers to treat exhaust gas containing sulfur dioxide, and can be desorbed and recycled.

type of desulfurizer

P> At present, the desulfurizers with more research and industrialization mainly include the following: amine desulfurizer, activated carbon desulfurizer, iron-based desulfurizer, zinc-based desulfurizer, copper-based desulfurizer and manganese-based desulfurizer. The following mainly discusses the research progress of the above-mentioned desulfurizer at home and abroad.

1. amine desulfurizer

P> Since the 30s of the last century, amine desulfurizers have been the main means of industrial gas purification. Alkanolamine is used as absorption desulfurization. At present, basic solvents developed include monoethanolamine (MEA), ethylene glycol amine (DEA), diisopropanolamine (DIPA), methyl diethanolamine (MDEA) and triethanolamine (TEA), among which monoethanolamine solution, it is commonly used as an acid gas absorbent to reduce the content of H2S to below 5mg/m3 and remove CO2 at the same time. It is a good solvent for absorption and desulfurization at present.

The method of recycling and reuse of monoethanolamine solution is relatively simple. The water washing method is mainly adopted. The specific operation method is to absorb and evaporate amine from the air stream, but monoethanolamine (MEA) and organic sulfide will react and it is difficult to regenerate, so monoethanolamine solution is only suitable for treating exhaust gas containing H2S.

diethanolamine (DEA) is a secondary alcohol amine. its reaction speed with organic sulfide and CS2 is slower than that with monoethanolamine (MEA), thus reducing the loss of absorbent caused by the reaction of diethanolamine (DEA.

diisopropanolamine (DIPA) can selectively remove a small amount of H2S and COS from CO2. The reaction speed of CS2 is slower than that of monoethanolamine (MEA), thus reducing the loss of absorbent caused by the reaction of diethanolamine (DEA) and organic sulfide. Therefore, diethanolamine is more suitable for desulfurization of refinery gas and coal chemical tail gas, and diethanolamine DEA has the same removal effect on CO2 and H2S. Diisopropanolamine (DIPA) can selectively remove a small amount of H2S and COS from CO2.

methyl diethanolamine (MDEA) is a tertiary amine, which has the advantages of high concentration, high acid gas load, low corrosivity, strong anti-degradation ability, high desulfurization selectivity, low energy consumption, etc. When H2S and CO2 coexist, the selectivity to H2S is superior to other alkanolamines. Since the 1980s, it has been widely promoted and applied. Methyl diethanolamine (MDEA) solvent has poor thermodynamic selectivity to H2S, and the removal ratio of organic sulfide is lower. The difference in reaction speed between methyl diethanolamine (MDEA) and H2S and CO2 is used to realize the dynamic selection of H2S and meet the requirements of industrial production. However, when treating mixed gas with high CO2/H2S volume ratio or gas with high H2S content, the requirements of purification degree and selective separation will be contradictory, and the H2S content in the acid gas produced by it may be low, which will make the operation of Claus sulfur recovery unit difficult. At the same time, methyl diethanolamine (MDEA) aqueous solution still has problems such as poor anti-pollution ability and easy foaming of the solution. In view of the above reasons, the current research and development of methyldiethanolamine (MDEA) mainly focuses on the following two aspects. On the one hand, MDEA and organic solvent are prepared to form a mixed solvent, thus reducing the water content in the solvent. For example, sulfolane has good dissolving ability to organic sulfide and hydrogen sulfide, and can selectively remove hydrogen sulfide. The second is to synthesize various sterically hindered amines, and the selectivity of sterically hindered amines is better than MDEA.

P> After more than half a century of development, a variety of amine desulfurizers have been developed. At present, MDEA aqueous solution and its modified solvent are widely used in industrialization, which is also the future development trend of amine desulfurization process.

2. Activated carbon desulfurizer

Activated carbon is a kind of porous carbon, low bulk density, large specific surface area, and good thermal stability. It is currently widely used low-temperature desulfurizer. Activated carbon as a desulfurizer has the role of adsorption and catalysis, desulfurization operating temperature is generally controlled in the range of 50~60 ℃, the principle of activated carbon desulfurization mainly depends on the active group on the surface of the activated carbon on the catalytic reaction of oxygen and sulfide to achieve the purpose of desulfurization. Activated carbon desulfurizer has a large sulfur capacity and high desulfurization accuracy, but it can only be used in aerobic atmosphere.

3. Iron-based desulfurizer

Iron-based desulfurizers traditionally use iron oxide, which has a large sulfur capacity but low desulfurization accuracy. Iron oxide has desulfurization activity in the two hydrate forms of α-Fe2O3 · H2O and & gamma;-Fe2O3 · H2O. The desulfurization mechanism of iron oxide desulfurizer is that H2S molecules first diffuse to the particle surface of iron oxide hydrate, and then dissociate in the water film. The dissociated HS-and S2-ions are replaced with lattice oxygen (OH-, O2-) in hydrated iron oxide to generate Fe2S3 hydrate and FeS.

4. Zinc-based desulfurizer

zinc oxide desulfurizer has good desulfurization accuracy and is widely used at present. the chemical reaction coefficient of zinc oxide desulfurizer with H2S is relatively large, which can reduce the mole fraction of H2S at the outlet to below 10-5. when hydrogen is contained in the reaction gas, sulfides such as carbonyl sulfide, carbon disulfide, mercaptan, thioether, etc. will react under certain reaction conditions to generate H2S, and then react. Increasing the reaction temperature can increase the sulfur capacity of the zinc oxide desulfurizer; the reaction temperature generally requires Confucius to be above 200 ℃ and enter the reaction high efficiency zone in the range of 600~700 ℃. At this time, the reaction is fast and thorough; but when the temperature exceeds 600 ℃, ZnO is easy to be reduced to elemental Zn and volatilization is lost; during the regeneration process of zinc oxide desulfurizer, the operating temperature is too low, which may. When zinc oxide desulfurizer is desulfurized at low temperature, the sulfur capacity is low, but the desulfurization accuracy is high. Therefore, improving the low-temperature sulfur capacity of zinc-based desulfurizers has become the focus of research and development of metal desulfurizers.

5. Copper-based desulfurizer

Copper-based desulfurizers are often used for desulfurization under medium and high temperature conditions. In thermodynamics, the free enthalpy of the reaction between copper oxide and hydrogen sulfide and the desulfurization effect are the most advantageous.

6. Manganese-based desulfurizer

The lowest temperature for desulfurization of manganese-based desulfurizer is 200 ℃, so it is mostly used for medium and high temperature desulfurization. The older manganese-based desulfurizer uses natural manganese ore. Because natural manganese ore contains about 90% manganese dioxide, and when used as a desulfurizer, tetravalent manganese must be reduced to divalent before it has desulfurization activity. Although the sulfur capacity of manganese-based desulfurizer is low and the desulfurization accuracy is not high, it can convert a variety of organic sulfur, so it is often used in the crude desulfurization of coke oven gas or refinery gas. At present, a low price has been developed in China. Iron-manganese refined desulfurizer with certain organic sulfur conversion activity.

7. Biological desulfurization

biological desulfurization method is a new treatment method developed in the 1950s, which has the characteristics of low operating cost and no secondary pollution. The foreign Schell-Parker biological desulfurization process is currently the most representative biological desulfurization technology. It uses biotechnology to remove H2S from the gas-using a weakly alkaline solution to absorb, and then under the action of naturally occurring microorganisms and air The absorbed hydrogen sulfide is oxidized into elemental sulfur, and the generated biological sulfur has good hydrophilicity and will not block the process equipment, it can be used for feed gas with H2S concentration of 50 ppm to 100%( vol), and this technology can be adopted in the field of gas purification of small and medium-sized devices. The waste gas biological treatment technology developed by Sinopec Fushun Petrochemical Research Institute has obvious effect on treating sulfur-containing malodorous waste gas. It can remove a variety of pollutant components at the same time. It uses self-developed biological fillers, which are easy to adhere to microorganisms and have excellent moisture retention. Features, stable operation, strong practicability, and strong resistance to H2S load impact.

Last Update：2024-04-10 22:29:15