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KR-102965306-B1 - Method for producing methyl mercaptan having treatment of gaseous waste

KR102965306B1KR 102965306 B1KR102965306 B1KR 102965306B1KR-102965306-B1

Abstract

The present invention relates to a process for manufacturing methyl mercaptan, comprising: A) a step of reacting methanol with hydrogen sulfide to form a stream (M) preferably in gaseous form, comprising methyl mercaptan, unreacted H₂S , and possibly sulfur byproducts; B) Optionally, a step of condensing the stream (M); C) A step of performing at least one purification step of the stream (M) to obtain a stream concentrated with methyl mercaptan; D) a step of recovering a gas vent generated from at least one purification step, wherein the gas vent comprises at least one sulfur compound, preferably H₂S ; E) a step of performing gas-liquid extraction of at least one sulfur compound, preferably H₂S , using liquid methanol to obtain liquid methanol concentrated with sulfur compound(s), preferably H₂S ; and F) Optionally, the process comprises the step of using the concentrated methanol as a reagent for the reaction of step A).

Inventors

  • 프레미, 조르주
  • 레이몬드, 장-미셸
  • 라만트, 에릭

Assignees

  • 아르끄마 프랑스

Dates

Publication Date
20260513
Application Date
20211216
Priority Date
20201217

Claims (12)

  1. As a method for manufacturing methyl mercaptan, A) reacting methanol with hydrogen sulfide to form a stream (M) containing methyl mercaptan and unreacted H₂S , or containing methyl mercaptan, unreacted H₂S , and sulfur byproducts; C) A step of performing at least one purification step of the stream (M) to obtain a stream concentrated with methyl mercaptan; D) a step of recovering a gaseous vent generated from at least one purification step, wherein the gaseous vent comprises at least one sulfur compound; and E) a step of performing gas-liquid extraction of at least one sulfur compound using liquid methanol to obtain liquid methanol concentrated with sulfur compound(s), and In step E), the mass ratio of gas vent to methanol is 0.001 to 0.5, Method for manufacturing methyl mercaptan.
  2. A method for producing methyl mercaptan according to claim 1, wherein at least one phase separation step is performed during step C) and/or at least one purge is performed.
  3. A method for producing methyl mercaptan according to claim 1 or 2, wherein in step E), the mass ratio of gas vent to methanol is 0.005 to 0.1.
  4. A method for producing methyl mercaptan according to claim 1 or 2, wherein gas-liquid extraction is performed at a temperature of 0°C to 80°C.
  5. A method for producing methyl mercaptan according to claim 1 or 2, wherein gas-liquid extraction is performed at a pressure of 4 to 60 absolute bar.
  6. A method for producing methyl mercaptan according to claim 1 or 2, wherein the concentrated methanol is used as a reagent for the reaction of step A) as a mixture with fresh methanol.
  7. A method for producing methyl mercaptan according to claim 1 or 2, wherein the concentrated methanol comprises 0.1% by weight to 20% by weight of H₂S with respect to the total weight of the concentrated methanol.
  8. A method for producing methyl mercaptan according to claim 1 or 2, wherein the gas vent comprises H₂S , methyl mercaptan, and an inert compound.
  9. A method for producing methyl mercaptan according to claim 1 or 2, wherein gas-liquid extraction is performed in at least one absorption column or in at least one tank.
  10. In paragraph 1, after step A, B) Step of condensing the above stream (M) A method for producing methyl mercaptan, further comprising
  11. In paragraph 1, after step E, F) A step of using the above concentrated methanol as a reagent for the reaction of step A). A method for producing methyl mercaptan, further comprising
  12. A method for producing methyl mercaptan according to claim 1, wherein the sulfur compound is H₂S .

Description

Method for producing methyl mercaptan having treatment of gaseous waste The present invention relates to a method for producing methyl mercaptan, comprising the treatment of gas emissions. The present invention also relates to a process for treating gas emissions from a methyl mercaptan production unit. Mercaptans are receiving significant industrial interest and are currently widely used in the chemical industry as starting materials, particularly in the synthesis of more complex organic molecules. For example, methyl mercaptan ( CH₃SH or MeSH) is used as a starting material in the synthesis of methionine, an essential amino acid for animal nutrition. Methyl mercaptan is also used in the synthesis of dialkyl disulfides, particularly in the synthesis of dimethyl disulfide (DMDS), a sulfide additive for the hydrotreatment of catalysts for petroleum fractionation, among other applications. The industrial synthesis of methyl mercaptan can occur according to the "methanol pathway" starting with methanol and hydrogen sulfide according to the following reaction scheme (1): [Reaction Equation 1] CH 3 OH + H 2 S → CH 3 SH + H 2 O Equation (1) is generally carried out in the gaseous phase with an excess of H₂S . Additionally, at the industrial level, gaseous emissions (also called gaseous vents) can be released throughout the production process. These emissions are typically treated by incineration. However, they contain very high concentrations of H₂S , and their combustion during incineration will cause high sulfur dioxide emissions into the atmosphere ( SO₂ is a pollutant and irritant gas, which can cause acid rain). Furthermore, the loss of these H₂S increases the variable production costs of methyl mercaptan and reduces productivity. Therefore, a process for manufacturing methyl mercaptan that is more environmentally friendly and more economical is required. In addition, it is necessary to reduce gas emissions, and in particular sulfur dioxide, released during the production of methyl mercaptan. One objective of the present invention is to provide a process for producing methyl mercaptan that enables improved management of gas emissions and is particularly more environmentally friendly. One objective of the present invention is to reduce the amount of gas emissions, and in particular sulfur dioxide, released during the production of methyl mercaptan. Another objective of the present invention is to provide a more economical process for producing methyl mercaptan. Another objective of the present invention is to provide a process and/or device for treating gas emissions that can be easily integrated into a unit for producing methyl mercaptan, particularly through a methanol route. The present invention satisfies all or part of the aforementioned purpose. The inventors have surprisingly discovered that gas effluents can be recovered and treated by gas-liquid extraction. Gas (vent gas)-liquid (methanol) extraction according to the present invention makes it possible to move sulfur compounds contained in said gas vents into liquid methanol. The term "sulfur compound" means a compound containing at least one sulfur atom, preferably one or two sulfur atoms. In particular, the term "sulfur compound" means H₂S , methyl mercaptan, and sulfur byproducts, such as dimethyl sulfide (DMS) and dimethyl disulfide (DMDS). Accordingly, gas-liquid extraction according to the present invention makes it possible to recover at least one sulfur compound, preferably H₂S , from methanol. In particular, gas-liquid extraction according to the present invention makes it possible to recover H₂S and methyl mercaptan from methanol. Highly advantageously, the methanol concentrated with sulfur compound(s) can be used as a reagent to form methyl mercaptan, and preferably can be used directly (e.g., without a purification step). Thus, the present invention makes it possible to reintroduce H₂S and possibly methyl mercaptan from vent gas that has been incinerated into a production process. Furthermore, the above extraction allows inert compounds to pass through (i.e., inert compounds hardly proceed from the vent gas into methanol but remain in the gaseous phase). This prevents their accumulation in the equipment and consequent clogging and resulting safety issues. In particular, hydrogen ( H₂ ) does not proceed into the methanol, which avoids undesirable methanation reactions in the reactor when concentrated methanol is used as a reagent in the production of methyl mercaptan. Such reactions are specifically as follows: CH 3 OH + H 2 → CH 4 + H 2 O and CH 3 SH + H 2 → CH 4 + H 2 S. It is understood that the extraction according to the present invention is not intended to directly recover sulfur compounds, and in particular unreacted H₂S , from the outlet of a reactor for the production of methyl mercaptan from methanol and H₂S . The extraction according to the present invention also does not aim to recover or recirculate most of the unreacted H₂S .