Catalyst for oxidation reactions, a method for its preparation and the use thereof

Abstract

The present invention relates to a catalyst for oxidation reactions, particularly for oxidation of mercaptan dialkyldisulfides and/or dialklypolysulfides with oxygen to alkanesulfonic acids.

Claims

1. A catalyst according to general formula (I):
Q.sub.a[M.sub.b(VO.sub.4).sub.c].sup.a(I), wherein Q is a quaternary ammonium cation of the general formula (II)
R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+(II), wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is independently of each other a saturated C.sub.1 to C.sub.20 alkyl radical or an aromatic C.sub.5 or C.sub.6 radical with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is a saturated C.sub.4 to C.sub.20 alkyl group, M is at least one metal selected from the group consisting of alkali metals, alkaline earth metals, group III metals and transition metals, V denotes vanadium, O denotes oxygen, a is an integer from 1 to 3, b is the integer 1 or 2, and c is the integer 1 or 2.

2. The catalyst according to claim 1, wherein Q is a quaternary ammonium cation according to the general formula (III):
(C.sub.nH.sub.2n+1).sub.o(CH.sub.3).sub.4oN.sup.+(III), wherein n is an integer from 4 to 18, and o is an integer from 1 to 4.

3. The catalyst according to claim 2, wherein Q is selected from the group of quaternary ammonium cations consisting of (C.sub.4H.sub.9).sub.4N.sup.+, (C.sub.4H.sub.9).sub.3(CH.sub.3)N.sup.+, (C.sub.4H.sub.9).sub.2(CH.sub.3).sub.2N.sup.+, (C.sub.4H.sub.9)(CH.sub.3).sub.3N.sup.+, (C.sub.8H.sub.17).sub.4N.sup.+, (C.sub.8H.sub.17).sub.3(CH.sub.3)N.sup.+, (C.sub.8H.sub.17).sub.2(CH.sub.3).sub.2N.sup.+, (C.sub.8H.sub.17)(CH.sub.3).sub.3N.sup.+, (C .sub.12H.sub.25).sub.4N.sup.+, (C .sub.12H.sub.25).sub.3 (CH.sub.3)N.sup., (C.sub.12H.sub.25).sub.2(CH.sub.3).sub.2N.sup.+, (C.sub.12H.sub.25)(CH.sub.3).sub.3N.sup.+, (C.sub.16H.sub.33).sub.4N.sup.+, (C.sub.16H.sub.33).sub.3(CH.sub.3)N.sup.+, (C.sub.16H.sub.33).sub.2(CH.sub.3).sub.2N.sup.+, (C.sub.16H.sub.33)(CH.sub.3).sub.3N.sup.+, (C.sub.18H.sub.37).sub.4N.sup.+, (C.sub.18H.sub.27).sub.3(CH.sub.3)N.sup.+, (C .sub.18H.sub.37).sub.2(CH.sub.3).sub.2N.sup.+, (C.sub.18H.sub.37)(CH.sub.3).sub.3N.sup.+, ((C.sub.18H.sub.37).sub.75%(C.sub.16H.sub.33).sub.25%).sub.2(CH.sub.3).sub.2N.sup.+and combinations thereof.

4. The catalyst according to claim 3, wherein Q is (C.sub.16H.sub.33).sub.4N.sup.+, (C.sub.16H.sub.33).sub.3(CH.sub.3)N.sup.+, (C.sub.16H.sub.33).sub.2(CH.sub.3).sub.2N.sup.+, or (C.sub.16H.sub.33)(CH.sub.3).sub.3N.sup.+or combinations thereof.

5. The catalyst according to claim 1, wherein the metal M is selected from the group consisting of Mg, Co, Cu, Fe, Ba, Zr and combinations thereof.

6. The catalyst according to claim 5, wherein the metal M is Mg.

7. The catalyst according to claim 5, wherein a is 1, b is 1 and c is 1.

8. The catalyst according to claim 6, wherein the catalyst is a compound of the formula C.sub.16H.sub.33(CH.sub.3).sub.3)N.sup.+[MgVO.sub.4].sup..

9. The catalyst according to claim 1 that is suitable for oxidation reactions.

10. A method for the production of a catalyst according to claim 1, which comprises: a) providing a solution of a salt of the metal M in nitric acid, b) adding a salt of the quaternary ammonium cation Q to the solution obtained in a), c) adding a solution of a salt of an orthovanadate to the solution obtained in b), d) stirring the solution obtained in c), e) concentrating the solution of d) under reduced pressure to give a catalytically active mass, and f) drying the catalytically active mass obtained in e).

11. The method according to claim 10, wherein the sequence of b) and c) is exchanged.

12. A method for oxidation of a sulfur containing hydrocarbon compound comprising contacting a catalyst according to claim 1 with at least one sulfur containing hydrocarbon compound.

13. The method according to claim 12 that comprises oxidation of alkylmercaptan to dialkyldisulfide and/or at least one alkanesulfonic acid with oxygen or hydrogen peroxide as an oxidizing agent in the presence or absence of nitric acid, or oxidation of dialkyldisulfide to alkanesulfonic acid with oxygen or hydrogen peroxide as oxidizing agent in the presence or absence of nitric acid or the oxidation of dialkylpolysulfide to alkanesulfonic acid with oxygen or hydrogen peroxide as oxidizing agent in the presence or absence of nitric acid.

14. The method according to claim 13, that comprises oxidation of methylmercaptan to dimethyldisulfide and/or methanesulfonic acid with oxygen or hydrogen peroxide as oxidizing agent in the presence or absence of nitric acid, or oxidation of dimethyldisulfide to methanesulfonic acid with oxygen or hydrogen peroxide as oxidizing agent in the presence or absence of nitric acid or the oxidation of dimethylpolysulfide to methanesulfonic acid with oxygen or hydrogen peroxide as oxidizing agent in the presence or absence of nitric acid.

15. A process for the preparation of alkanesulfonic acid comprising: a) providing a solution comprising a sulfur containing hydrocarbon compound and a catalyst according to claim 1 in an organic solvent, b) introducing oxygen or hydrogen peroxide into a reaction system, and c) stirring the resulting mixture.

16. The process according to claim 15, wherein water is added in an amount which is sufficient to give the desired alkanesulfonic acid.

17. The process according to claim 15, wherein the sulfur containing hydrocarbon compound is methylmercaptan or dimethyldisulfide.

18. The process according to claim 15, wherein the organic solvent is selected from the group consisting of optionally substituted alkanes, optionally substituted aromatic hydrocarbons, esters, ethers, ketones, alcohols, carboxylic acids, nitriles amides, sulfones, sulfoxides, alkanesulfonic acids and combinations thereof.

19. The process according to claim 15, wherein the process is performed at a pressure of from 10 bar to 120 bar.

20. The process according to claim 15, wherein the process is performed at a temperature of from 40 C. to 150 C.

21. A catalyst according to general formula (I):
Q.sub.a[M.sub.b(VO.sub.4).sub.c].sup.a(I), wherein Q is a quaternary ammonium cation of the general formula (II)
R.sup.1R.sup.2R.sup.3R.sup.4N.sup.1(II), wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is independently of each other a saturated C.sub.1 to C.sub.20 alkyl radical or an aromatic C.sub.5 or C.sub.6 radical with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is a saturated C.sub.4 to C.sub.20 alkyl group, M is at least one metal selected from the group consisting Mg, Co, Cu, Fe, Ba, Zr and combinations thereof, V denotes vanadium, O denotes oxygen, a is an integer from 1 to 3, b is the integer 1 or 2, and c is the integer 1 or 2.

22. The catalyst according to claim 21, wherein a is 1, b is 1 and c is 1.

Description

EXAMPLES

(1) I. Preparation of the Catalysts

Example 1

Preparation of C16H33(CH3)3N+[MgVO4] (MgV catalyst)

(2) Magnesium nitrate hexahydrate (0.53 g) and a solution of nitric acid (30 ml, 0.1 mol/l) were placed in a 100 l flask. The thus obtained mixture was stirred for 30 minutes and afterwards, hexadecyltrimethylammonium chloride (0.33 g) was added to this mixture and the resulting suspension was stirred for another 60 minutes. To this suspension, a solution of sodium orthovanadate dodecahydrate (4 g) in nitric acid (20 ml, 0.1 g/l) was added and the resulting mixture was stirred at room temperature for 24 hours. Subsequently, the mixture was concentrated under reduced pressure using a rotary evaporator and dried at 100 C. for 4 hours.

Example 2

Preparation of C16H33(CH3)3N+[CoVO4] (CoV catalyst)

(3) Cobalt nitrate hexahydrate (2.33 g) was dissolved in nitric acid (120 ml, 0.1 mol/l) at room temperature. The resulting solution was placed in a 500 ml flask and stirred for 10 minutes. Subsequently, a solution of sodium orthovanadate dodecahydrate (16 g) in water (80 ml) was added and the thus obtained suspension was stirred for 30 minutes. To this suspension, hexadecyltrimethylammonium chloride (1.28 g) was added and the resulting mixture was stirred at room temperature for 24 hours. Afterwards, the mixture was concentrated under reduced pressure using a rotary evaporator and dried at 100 C. for 4 hours.

Example 3

Preparation of C16H33(CH3)3N+[CuVO4] (CuV catalyst)

(4) The CuV catalyst was prepared using the procedure of example 2, except that cobalt nitrate hexahydrate was replaced with cupric nitrate hydrate (1.93 g).

Example 4

Preparation of C16H33(CH3)3N+[FeVO4] (FeV catalyst)

(5) Iron(III) nitrate nonahydrate (4 g) was placed in a 100 ml flask, dissolved in nitric acid (30 ml, 0.1 mol/l) at room temperature and the resulting solution stirred for 30 minutes. A solution of sodium orthovanadate dodecahydrate (4 g) in water (20 ml) was added and the resulting suspension was stirred for another 30 minutes. To this suspension, hexadecyltrimethyl-ammonium chloride (0.32 g) was added and the thus obtained mixture was stirred at room temperature for 24 hours. This mixture was concentrated under reduced pressure using a rotary evaporator and dried at 100 C. for 4 hours.

Example 5

Preparation of C16H33(CH3)3N+[BaVO4] (BaV catalyst)

(6) Barium chloride dihydrate (0.84 g) was placed in a 250 ml flask, dissolved in nitric acid (60 ml, 0.1 mol/l) at room temperature and the resulting solution stirred for 10 minutes.

(7) Subsequently, hexadecyltrimethylammonium chloride (0.64 g) was added and the thus obtained mixture was stirred at room temperature for 30 minutes. To this mixture, a solution of sodium orthovanadate dodecahydrate (8 g) in water (40 ml) was added and the resulting mixture was stirred at room temperature for 24 hours. This mixture was concentrated under reduced pressure in a rotary evaporator and dried at 100 C. for 4 hours.

Example 6

Preparation of C16H33(CH3)3N+[ZrVO4] (ZrV catalyst)

(8) The ZrV catalyst was prepared using the procedure of example 5, except that barium chloride dehydrate was replaced with zirconium nitrate pentahydrate.

Example 7

Preparation of C16H33(CH3)3N+[NaVO4] (NaV catalyst)

(9) The NaV catalyst was prepared using the procedure of example 4, except that iron(III) nitrate nonahydrate was replaced with sodium chloride (0.12 g).

Example 8

Preparation of (C16H33(CH3)3N+)3[Al(VO4)2]3 (AlV catalyst)

(10) The NaV catalyst was prepared using the procedure of example 4, except that iron(III) nitrate nonahydrate was replaced with aluminum nitrate (0.75 g).

Comparative Example 1

Preparation of C16H33(CH3)3N+[NaWO4] (NaW catalyst)

(11) Sodium chloride (0.1 g) was placed in a 100 ml flask, dissolved in nitric acid (30 ml, 0.1 mol/l) and the resulting solution was stirred for 10 minutes. Subsequently, a solution of sodium tungstate dehydrate (3.3 g) in 20 ml water was added and the thus obtained suspension was stirred for 20 minutes. Following, hexadecyltrimethylammonium chloride (0.32 g) was added and the resulting mixture was stirred at room temperature for 24 hours. The suspension was filtered, and the wet filter cake was dried at 60 C. for 4 hours.

Comparative Example 2

Preparation of C16H33(CH3)3N+[Mg0.5WO4] (MgW catalyst)

(12) Magnesium nitrate hexahydrate (0.225 g) was placed in a 100 ml flask, dissolved in nitric acid (30 ml, 0.1 mol/l) and the resulting solution was stirred for 10 minutes. Subsequently, a solution of sodium tungstate dehydrate (3.3 g) in 20 ml water was added and the thus obtained suspension was stirred for 10 minutes. Following, hexadecyltrimethylammonium chloride (0.32 g) was added and the resulting mixture was stirred at room temperature for 24 hours. The suspension was filtered, and the wet filter cake was dried at 60 C. for 4 hours.

Comparative Example 3

Preparation of C16H33(CH3)3N+[Al(WO4)2] (AlW catalyst)

(13) The AlW catalyst was prepared using the procedure of comparative example 2, except that magnesium nitrate hexahydrate was replaced with aluminum nitrate (0.75 g).

Comparative Example 4

Preparation of C16H33(CH3)3N+[Cu0.5WO4] (CuW catalyst)

(14) Cupric nitrate (0.69 g) was placed in a 100 ml flask, dissolved in nitric acid (60 ml, 0.1 mol/l) and the resulting solution was stirred for 10 minutes. Subsequently, a solution of sodium tungstate dehydrate (6.6 g) in 40 ml water was added and the thus obtained suspension was stirred for 10 minutes. Following, hexadecyltrimethylammonium chloride (0.64 g) was added and the resulting mixture was stirred at room temperature for 24 hours. The suspension was filtered, and the wet filter cake was dried at 60 C. for 4 hours.

(15) II. Catalysts Activities in Oxidation of Methylmercaptan with Hydrogen Peroxide to Dimethyldisulfide and Methansulfonic Acid

Comparative Example 5

Oxidation with the NaW Catalyst

(16) A solution of methylmercaptan in acetonitrile (77 g, 13.5%) was placed in a three-neck flask and 0.12 g of the MgW catalyst of comparative example 1 was added. The thus obtained reaction mixture was stirred at room temperature and hydrogen peroxide solution (99.7 g) was added dropwise at a temperature of less 40 C. within one hour. The resulting mixture was stirred at room temperature for 24 hours. The solvent was removed under reduced pressure using a rotary evaporator. The yield for methanesulfonic acid was 47.5% and the yield for sulfuric acid was 1.1%.

Comparative Example 6

Oxidation with the use of the MgW Catalyst

(17) A solution of methyl mercaptan in acetonitrile (78 g, 16.5%) was placed in a three-neck flask and 0.15 g of the MgW catalyst of comparative example 2 was added. The thus obtained reaction mixture was stirred at room temperature and a hydrogen peroxide solution (122.4 g) was added dropwise at a temperature of less 40 C. within one hour. The resulting mixture was stirred at room temperature for 24 hours. The solvent was removed under reduced pressure using a rotary evaporator. The yield for methylsulfonic acid was 37.7% and the yield for sulfuric acid was 0.6%.

Comparative Example 7

Oxidation with the AlW Catalyst

(18) A solution of methylmercaptan in acetonitrile (77 g, 13.5% in acetonitrile) was placed in a three-neck flask and 0.12 g of the AlW catalyst of comparative example 3 was added at room temperature. The thus obtained reaction mixture was stirred at room temperature and 99.8 g of a hydrogen peroxide solution was added dropwise at a temperature of less 40 C. over a period of one hour. The resulting mixture was stirred at room temperature for 24 hours. The solvent was removed under reduced pressure using a rotary evaporator. The yield for methanesulfonic acid was 41.7% and the yield for sulfuric acid was 1%.

Comparative Example 8

Oxidation with the use of the CuW Catalyst

(19) A solution of methylmercaptan in acetonitrile (78 g, 16.5% in acetonitrile) was placed in a three-neck flask and 0.15 g of the CuW catalyst of comparative example 4 was added. The thus obtained reaction mixture was stirred at room temperature and a hydrogen peroxide solution (99.8 g) was added dropwise at a temperature of less 40 C. over a period of one hour. The resulting mixture was stirred at room temperature for 24 hours. The solvent was removed under reduced pressure using a rotary evaporator. The yield for methylsulfonic acid was 41.7% and the yield for sulfuric acid was 1%.

Example 9

Oxidation with the use of the MgV Catalyst

(20) A solution of methyl mercaptan in acetonitrile (78 g, 16.5%) was placed in a three-neck flask and the MgV catalyst of example 1 (0.12 g) was added. The thus obtained reaction mixture was stirred at room temperature and hydrogen peroxide solution (122.5 g) was added dropwise at a temperature of less 40 C. over a period of one hour. The resulting mixture was stirred at room temperature for 24 hours. The solvent was removed under reduced pressure using a rotary evaporator. The yield for methanesulfonic acid was 63.9% and the yield for sulfuric acid was 0.4%.

(21) TABLE-US-00001 TABLE 1 Results of the comparative examples 5 to 8 and of example 9 Yield [%] Example Catalyst T [ C.] MSA H.sub.2SO.sub.4 comp. C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[NaWO.sub.4].sup. 40 47.5 1.1 example 5 comp. C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[Mg.sub.0.5WO.sub.4].sup. 40 37.7 0.6 example 6 comp. (C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+).sub.3[Al(WO.sub.4).sub.2].sup. 40 41.7 1 example 7 comp. C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+ [Cu.sub.0.5WO.sub.4].sup. 40 41.7 1 example 8 example 9 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. 40 63.9 0.4
III. Catalysts Activities in the Oxidation of Dimethyldisulfide with Oxygen to Methanesulfonic Acid

Comparative Example 9

Without a Catalyst Under Oxygen Atmosphere (10 Bar)

(22) A reaction mixture of dimethyldisulfide (15.02 g) and acetonitrile (150 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (10 bar) for 24 hours. The conversion of dimethyldisulfide was 4.4% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 0.88%.

Comparative Example 10

Oxidation without a Catalyst Under Oxygen Atmosphere (40 Bar)

(23) A reaction mixture of dimethyldisulfide (15.14 g) and acetonitrile (150 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 0.4% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 0.87%.

Example 10

Oxidation using the MgV Catalyst Under Oxygen Atmosphere (10 Bar)

(24) A reaction mixture of dimethyldisulfide (15.18 g), acetonitrile (153 g) and the MgV catalyst of example 1 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (10 bar) for 24 hours. The conversion of dimethyldisulfide was 73% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 53.7%.

Example 11

Oxidation using the MgV Catalyst Under Oxygen Atmosphere (40 Bar)

(25) A reaction mixture of dimethyldisulfide (15.2 g), acetonitrile (150 g) and the MgV catalyst of example 1 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 73% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 56%.

Example 12

Oxidation using the CoV Catalyst Under Oxygen Atmosphere (40 Bar)

(26) A reaction mixture of dimethyldisulfide (15.14 g), acetonitrile (150 g) and the CoV catalyst of example 2 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 16% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 8.7%.

Example 13

Oxidation using the CuV Catalyst Under Oxygen Atmosphere (40 Bar)

(27) A reaction mixture of dimethyldisulfide (15 g), acetonitrile (150 g) and the CuV catalyst of example 3 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 37% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 22.4%.

Example 14

Oxidation using the FeV Catalyst Under Oxygen Atmosphere (40 Bar)

(28) A reaction mixture of dimethyldisulfide (15.02 g), acetonitrile (150.34 g) and the FeV catalyst of example 4 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 20% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 11.3%.

Example 15

Oxidation using the BaV Catalyst Under Oxygen Atmosphere (40 Bar)

(29) A reaction mixture of dimethyldisulfide (15.02 g), acetonitrile (150.1 g) and the BaV catalyst of example 5 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 32% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 10.2%.

Example 16

Oxidation using the ZrV Catalyst Under Oxygen Atmosphere (40 Bar)

(30) A reaction mixture of dimethyldisulfide (15.14 g), acetonitrile (150 g) and the ZrV catalyst of example 6 (0.15 g) was placed in a 500 ml autoclave and stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. The conversion of dimethyldisulfide was 11% (based on results obtained through gas chromatography) and the yield for the formation of methanesulfonic acid was 6.5%.

(31) TABLE-US-00002 TABLE 2 Results of the comparative examples 9 and 10 and of the examples 10 to 16 T p(O.sub.2) C.sub.DMDS Yield [%] Example Catalyst [ C.] [bar] [%] MSA H.sub.2SO.sub.4 comp. example 9 90 10 4.4 0.88 0 comp. example 10 90 40 0.4 0.87 0 example 10 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. 90 10 73 53.7 0.03 example 11 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. 90 40 73 56 0.2 example 12 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[CoVO.sub.4].sup. 90 40 16 8.7 0 example 13 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[CuVO.sub.4].sup. 90 40 37 22.4 0.72 example 14 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[FeVO.sub.4].sup. 90 40 20 11.3 0.16 example 15 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[BaVO.sub.4].sup. 90 40 32 10.2 0 example 16 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[ZrVO.sub.4].sup. 90 40 11 6.5 0
IV. Catalyst Activity in the Oxidation of Methylmercaptan with Oxygen to Dimethyldisulfide and Methanesulfonic

Example 17

Oxidation using the MgV Catalyst

(32) A solution of methylmercaptan in acetonitrile (9.1%, 150 g) was placed in a 500 ml autoclave and the MgV catalyst C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. (0.15 g) was added at room temperature. The reaction mixture was stirred at 90 C. under an oxygen atmosphere (40 bar) for 24 hours. Following, the reaction mixture was cooled to room temperature and analyzed. The conversion of methylmercaptan was 71%; the yield for the formation of dimethyldisulfide was 40% and the yield for the formation of methansulfonic acid was 4.2%.

(33) V. Catalyst Activity in the Oxidation of Dimethyldisulfide with Oxygen to Methanesulfonic at Different Oxygen Pressures

Comparative Example 11

Oxidation without a Catalyst Under Oxygen Atmosphere (10 Bar)

(34) A solution of dimethyldisulfide in acetonitrile (9.1%, 150 g) was placed in a 500 ml autoclave at room temperature. No catalyst was added to this solution. The reaction mixture was heated at 90 C. and stirred under oxygen atmosphere (10 bar) for 24 hours. Following, the reaction mixture was cooled to room temperature and analyzed. The yield for the formation of methanesulfonic acid was 0.9%.

Example 18

Oxidation using the MgV Catalyst at Reflux

(35) A solution of dimethyldisulfide in acetonitrile (9%, 111 g) was placed in a three-neck flask and the MgV catalyst C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. (0.15 g) was added. The resulting reaction mixture was heated at 80 C. under oxygen atmosphere (gas sparging with 40 ml/min to 60 ml/min) for 24 hours. Since the reaction was performed under oxygen flow, the reaction temperature was lower than the boiling point of acetonitrile. Thus, the reaction mixture was stirred under slight reflux. In this way a loss of dimethyldisulfide could be avoided. The yield for the formation of methansulfonic acid was 0.1% and the yield for the formation of sulfuric acid was 0.006%.

Example 19

Oxidation using the MgV Catalyst Under Oxygen Atmosphere (10 Bar)

(36) A solution of dimethyldisulfide in acetonitrile (9.1%, 150 g) and the MgV catalyst C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. (0.15 g) was placed in a 500 ml autoclave at room temperature. This reaction mixture heated at 90 C. and stirred under oxygen atmosphere (10 bar) for 24 hours. Following, the reaction mixture was cooled to room temperature and analyzed. The yield for the formation of methanesulfonic acid was 53.7% and the yield for the formation was 0.3%.

Example 20

Oxidation using the MgV Catalyst Under Oxygen Atmosphere (40 Bar)

(37) A solution of dimethyldisulfide in acetonitrile (9.1%, 150 g) and the MgV catalyst C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. (0.15 g) was placed in a 500 ml autoclave at room temperature. This reaction mixture heated at 90 C. and stirred under oxygen atmosphere (40 bar) for 24 hours. Following, the reaction mixture was cooled to room temperature and analyzed. The conversion of dimethyldisulfide was 73%; the yield for the formation of methanesulfonic acid was 55% and the yield for the formation was 0.2%.

Example 21

Oxidation using the MgV Catalyst Under Oxygen Atmosphere (40 Bar) with Water

(38) A solution of dimethyldisulfide in acetonitrile (9.1%, 150 g), the MgV catalyst C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+[MgVO.sub.4].sup. (0.15 g) and water (2.89 g) was placed in a 500 ml autoclave at room temperature. This reaction mixture heated at 90 C. and stirred under oxygen atmosphere (40 bar) for 24 hours. Following, the reaction mixture was cooled to room temperature and analyzed. The conversion of dimethyldisulfide was 96%; the yield for the formation of methanesulfonic acid was 92% and the yield for the formation was 0.4%.

(39) TABLE-US-00003 TABLE 3 Results of comparative example 11 without catalyst and of the examples 18 to 21 with the MgV catalyst of example 1 Reaction conditions Yield other Examples Concentration T [ C.] p [bar] t [h] MSA [%] H.sub.2SO.sub.4 [%] S balance [%] by-products comp. 9.1% in CH.sub.3CN 90 10 24 0.88 97.1 example 11 example 18 9.1% in CH.sub.3CN reflux 1 24 0.1 0.006 6.5 example 19 9.1% in CH.sub.3CN 90 10 24 53.7 0.03 81 CH.sub.3SO.sub.2CH.sub.3 CH.sub.3SO.sub.2SO.sub.2CH.sub.3 example 20 9.1% in CH.sub.3CN 90 40 24 55 0.2 81 CH.sub.3SO.sub.2CH.sub.3 CH.sub.3SO.sub.2SO.sub.2CH.sub.3 example 21 9.1% in CH.sub.3CN + 90 40 24 92 0.4 82 H.sub.2SO.sub.3 H.sub.2O* In context of the present invention the term S balance indicates the sulfur balance: $S\mathrm{balance}=\frac{\mathrm{moles}\mathrm{of}\mathrm{total}\mathrm{sulfur}\mathrm{derivative}\left(\mathrm{after}\mathrm{reaction}\right)}{\mathrm{moles}\mathrm{of}\mathrm{initial}\mathrm{sulfur}\mathrm{in}\mathrm{raw}\mathrm{material}}=\frac{\left(\mathrm{moles}\mathrm{of}\mathrm{sulfur}\mathrm{in}\mathrm{the}\mathrm{obtained}\mathrm{products}\mathrm{after}\mathrm{reaction}\right)+\left(\mathrm{moles}\mathrm{of}\mathrm{sulfur}\mathrm{in}\mathrm{the}\mathrm{remaining}\mathrm{educt}\mathrm{after}\mathrm{reaction}\right)}{\mathrm{moles}\mathrm{of}\mathrm{sulfur}\mathrm{in}\mathrm{the}\mathrm{educt}\mathrm{before}\mathrm{reaction}}.$An S balance of 100% indicates that there is no loss of sulfur in the reaction. Thus, all the products and by-products could be completely recovered, identified and quantified.