CATALYSTS FOR THE SYNTHESIS OF ALKANESULFONIC ACIDS

Abstract

The present invention relates to novel uses of stable inorganic peroxoacids as catalysts in the preparation of alkanesulfonic acids from alkanes and sulfur trioxide, methods for the production of alkanesulfonic acids employing said catalysts as well as reaction mixtures comprising said catalysts. The invention particularly relates to the production of methanesulfonic acid from methane and sulfur trioxide employing stable inorganic peroxoacids as catalysts.

Claims

1. A process of preparing an alkanesulfonic acid, the process comprising catalyzing a reaction of an alkane and sulfur trioxide with a compound comprising an inorganic peroxoacid or a salt thereof, wherein the inorganic peroxoacid is stable at room temperature.

2. The process of claim 1, wherein the inorganic peroxoacid comprises a peroxoacid of boron, silicon, phosphorus or sulfur.

3. The process of claim 1, wherein the inorganic peroxoacid is obtainable by reacting an oxoacid with a peroxide.

4. The process of claim 1, wherein the inorganic peroxoacid comprises a polyprotic acid comprising a peroxygroup OOX, wherein X is H, Li, Na and/or K.

5. The process of claim 4, wherein the polyprotic acid further comprises a group OX, wherein X is H, Li, Na and/or K.

6. The process of claim 1, wherein the inorganic peroxoacid comprises a reaction product of phosphoric acid with hydrogen peroxide, a reaction product of boric acid with hydrogen peroxide and/or potassium peroxomonosulfate.

7. A process of preparing an alkanesulfonic acid, the process comprising catalyzing a reaction of an alkane and sulfur trioxide with a mixture comprising hydrogen peroxide, an inorganic oxoacid and optionally a solvent.

8. The process of claim 7, wherein the inorganic oxoacid is a monoprotic acid or a polyprotic acid.

9. The process of claim 1, comprising: i) providing the sulfur trioxide; ii) reacting the sulfur trioxide with the alkane in a high-pressure autoclave or laboratory reactor; iii) setting a pressure of from 1 to 200 bar; iv) introducing the inorganic peroxoacid or the salt thereof; v) controlling a temperature of a reaction mixture at 0 C. to 100 C.; and vi) optionally purifying a reaction product.

10. The process of claim 7, comprising: i) providing the sulfur trioxide; ii) reacting the sulfur trioxide with the alkane in a high-pressure autoclave or laboratory reactor; iii) setting a pressure of from 1 to 200 bar; iv) introducing the inorganic oxoacid or a salt thereof, wherein the inorganic oxoacid or the salt thereof is optionally solved in the solvent, and the hydrogen peroxide, wherein the inorganic oxoacid or the salt thereof and the hydrogen peroxide are introduced sequentially or simultaneously; v) controlling a temperature of a reaction mixture at 0 C. to 100 C.; and vi) optionally purifying a reaction product.

11. The process of claim 9, wherein the alkane is methane and the alkanesulfonic acid is methanesulfonic acid.

12. A mixture comprising an alkane, sulfur trioxide, an inorganic peroxoacid stable at room temperature and optionally a solvent.

13. A mixture comprising an alkane, sulfur trioxide, an inorganic oxoacid, hydrogen peroxide and optionally a solvent, wherein the inorganic oxoacid is capable of forming an inorganic peroxoacid which is stable at room temperature.

14. The mixture of claim 12, wherein the alkane is methane.

15. The process of claim 1, wherein the alkane is methane and the alkanesulfonic acid is methanesulfonic acid.

16. The process of claim 10, wherein the alkane is methane and the alkanesulfonic acid is methanesulfonic acid.

17. The mixture of claim 13, wherein the alkane is methane.

Description

EXAMPLES

Example 1: Reaction Using Boronic Peroxide as Initiator

[0064] In a 3.75 L autoclave, 1000 g of 36% (w/w) oleum is charged, and the temperature controlled at 50 C. After a pressure of 100 bar of methane gas was set, intensive stirring is performed with a stirrer from the company Parr. Now, the initiator solution consisting of 100 ml sulfuric acid, 5.1 g boronic acid and 3.6 ml hydrogen peroxide (70%) is metered dropwise to the solution. The pressure drops to 34 bar within 4 hours. The yield is higher than 90%, based on sulfur trioxide. The reaction product contains 43% (w/w) methanesulfonic acid.

Example 2: Reaction Using Phosphoric Peroxide as Initiator

[0065] In a 3.75 L autoclave, 1000 g of 36% (w/w) oleum is charged, and the temperature controlled to 50 C. After a pressure of 100 bar of methane gas was set, intensive stirring is performed with a stirrer from the company Parr. Now, the initiator solution consisting of 100 ml sulfuric acid, 9,4 g phosphoric acid (85%) and 3.6 ml hydrogen peroxide (70%) is metered dropwise to the solution. The pressure drops to 30 bar within 4.5 hours. The yield is higher than 90%, based on sulfur trioxide. The reaction product contains 44% (w/w) methanesulfonic acid.