PROCESS FOR THE MANUFACTURING OF ALKANESULFONIC ACIDS

Abstract

A process for manufacturing of an alkanesulfonic acid, and an alkanesulfonic acid manufactured by the process. Aspects of the process may involve manufacturing an alkanesulfonic acid by reaction of an initiator composition with an alkane and sulfur trioxide by preparing an initiator composition by reacting aqueous hydrogen peroxide with alkanesulfonic acid and/or H.sub.2SO.sub.4; and reacting the initiator composition with sulfur trioxide and alkane to form an alkanesulfonic acid, wherein an alkane with a purity of at least 98.0 mol-% is used.

Claims

1. A process for manufacturing an methanesulfonic acid, the process comprising: preparing an initiator composition comprising reacting aqueous hydrogen peroxide with alkanesulfonic acid components and/or H.sub.2SO.sub.4; reacting the initiator composition with sulfur trioxide and methane to form methanesulfonic acid, wherein the methane in the reacting has a purity of at least 98.0 mol-%, and wherein the methane has a maximum content of hydrocarbons of 500 ppm.

2-3. (canceled)

4. The process of claim 1, wherein the methane has a purity of at least 98.5 mol-% in the reacting.

5. The process of claim 1, wherein the initiator composition in the preparing further comprises sulfur trioxide.

6. The process of claim 1, wherein the initiator composition in the preparing further comprises a recycle stream from a bottom purge of a distillation of methanesulfonic acid comprising methanesulfonic acid and sulfuric acid.

7. The process of claim 1, wherein the reacting is a radical reaction.

8. The process of claim 1, wherein the methanesulfonic acid in the reacting has an HAZEN number of less than 300.

9. The process of claim 1, further comprising: purifying the methanesulfonic acid obtained from the reacting.

10. The process of claim 9, wherein the purifying is a single step distillation or a multi step distillation.

11. The process of claim 1, wherein the purifying is a crystallization followed by a solid-liquid separation.

12. The process of claim 9, wherein the methanesulfonic acid obtained from the purifying has an HAZEN number of less than 300.

13. The process of claim 9, wherein the preparing is conducted in a reactor A, wherein the reacting is conducted in a reactor B or a set of reactors B, and wherein the purifying is conducted in a column or set of columns C, and wherein the reactor A, reactor B or set of reactors B, and column C are connected to conduct the process for the manufacturing of methanesulfonic acid continuously.

14. The process of claim 9, wherein the purifying is conducted in a distillation unit, wherein the preparing is conducted in a reactor A, wherein the reacting is conducted in a reactor B or a set of reactors B, and wherein a bottom product of the distillation is recycled into an upstream distillation column or into the reactor A or into the reactor or set of reactors B or drained.

15. The process of claim 13, wherein the purifying is conducted in a crystallization unit, wherein a crystallization mother liquor is recycled into the crystallization unit or into the reactor A or into the reactor B or drained.

16. The process of claim 9, wherein, after methanesulfonic acid is obtained from the purifying: providing methanesulfonic acid anhydride for subsequent charging of reactor A with alkanesulfonic acid anhydride.

17. The process of claim 1, wherein the methanesulfonic acid anhydride in the providing comprises a separated methanesulfonic acid anhydride manufacturing after the purifying or a methanesulfonic acid anhydride separation as side-component from the purifying.

18. The process of claim 1, wherein the preparing is conducted at a temperature in a range of from −5° C. to 25° C., wherein the reacting is conducted at a temperature in a range of from 25° C. to 80° C., and wherein the bottom of the column in the purifying is at a temperature in a range of from 30° C. to 220° C.

19. The process of claim 9, wherein the preparing is conducted at a pressure of at least 1013 mbar, wherein the reacting is conducted at a pressure in a range of from 10 bar to 150 bar, and wherein the purifying is conducted at a pressure in the column in a range of from 2 mbar to 1000 mbar.

20. The process of claim 9, wherein between the reacting and the purifying a flash is installed.

21. The process of claim 1, wherein the methane has undergone purification in a pressure swing absorption unit.

22-24. (canceled)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0105] In a first aspect the invention relates to a process for manufacturing of methane sulfonic acid (MSA) by reaction (for example radical reaction) of an initiator composition with methane and sulfur trioxide comprising the steps: [0106] i. Preparation of the initiator composition by mixing aqueous hydrogen peroxide (H.sub.2O.sub.2) with the components methane sulfonic acid (MSA), optionally sulfur trioxide (SO.sub.3) and optionally sulfuric acid (H2SO4) and optionally methane sulfonic acid anhydride (MSA anhydride or MSAA), [0107] ii. Reaction of the initiator composition from step i. with sulfur trioxide and methane to form MSA (preferably by radical reaction), wherein methane with a purity of at least 98 mol-% is used.

[0108] It was found that reduction of the percentage of hydrocarbons as listed above (see ranges quoted from Ullmann's Enzyklopädie), e.g. ethane and/or propane and/or butanes and/or C5-C8 alkanes in the methane used as educt had positive effects both on the product (yield, purity, colour number) and the manufacturing process (lower energy consumption).

[0109] In a preferred embodiment of the inventive process, methane with a purity of at least 98.0 mol-% is used.

[0110] In a further preferred embodiment of the inventive process, methane with a purity of at least 98.5 mol-% or 99.0 mol-% or 99.5 mol-% or even 99.7 or 99.8 or 99.9 mol-% is used.

[0111] It was also found that in an embodiment of the invention a combination of the components in step i. is suitable to form radicals as initiators for a subsequent radical reaction in combination with sulfur trioxide and methane. In step i. particularly the components aqueous hydrogen peroxide, methane sulfonic acid, optionally sulfur trioxide (SO.sub.3) and sulfuric acid and methane sulfonic acid anhydride are charged together in a reactor. Preferably, step i. comprises the substeps i1) and i2). In sub-step i1) for example the components aqueous hydrogen peroxide (H.sub.2O.sub.2), methane sulfonic acid (MSA) and sulfuric acid and methane sulfonic acid anhydride (MSA anhydride) are mixed together. In step i1) for example water is removed and anhydrous conditions are generated, in particular due to MSA anhydride. In sub-step ii2) for example sulfur trioxide (SO.sub.3) is added.

[0112] As process conditions for preparing the initiator composition the following parameters are preferably selected in step a) [0113] temperature preferably in the range from −5° C. to +25° C., and [0114] pressure preferably in the range from 0.5 bar to 10 bar, preferably in the range from 0.8 bar to 5 bar, most preferably close to normal pressure of approximately 1 bar (about 1013 mbar).

[0115] The amount of MSA anhydride added to the initiator composition (starter solution) in step a) is equivalent (calculated as mol, not as gram (g)) to the amount of water introduced with the H.sub.2O.sub.2 solution. It is for example to note that the H.sub.2O.sub.2 solution, the MSA anhydride, MSA, optionally sulfuric acid and optionally the recycle stream from the MSA distillation are combined first. In particular, sulfur trioxide (SO3) is introduced only after all free water has reacted with the MSA anhydride.

[0116] Optionally, the initiator composition in step i. further comprises sulfur trioxide (SO.sub.3). A further option for the initiator composition in step i. is a recycle stream from the bottom purge of the distillation of MSA comprising mainly MSA and H.sub.2SO.sub.4. In step i. of an embodiment of the invention an initiation mixture is prepared, which is suitable to form radicals at elevated temperature conditions or under photochemical initiation. The formation of radicals then takes place in a so-called initiation reaction. The radicals are particularly formed in the presence of methane and/or sulfur trioxide for example as part of step ii. Step i. yields a mixture comprising one or more of the components peroxo-monosulfuric acid (Caro's acid), peroxo-disulfuric acid (Marshall's acid), mono(methyl-sulfonyl)peroxide (MMSP) and/or di(methyl-sulfonyl)peroxide (DMSP), and besides, optionally, MSA and/or H2SO4. These components may act as intermediates, which further form in particular methyl radicals and/or methane sulfonic acid radicals in the synthesis of MSA according to an embodiment of step ii. Preferably, the radical reaction in an embodiment of step ii. comprises an initiation reaction and a propagation reaction.

[0117] The formation of radicals in an embodiment of the present invention in particular takes place in a separate step ii. wherein the initiator composition from step i. is brought in contact with methane and sulfur trioxide (initiation reaction). In a subsequent reaction (propagation reaction) which is preferably also part of an embodiment of step ii. then the formation of MSA takes place by reacting the initiator composition in a reaction with methane and sulfur trioxide, for example by radical reaction or at least partially a radical reaction.

[0118] In an embodiment of the present inventive process, in step ii. the temperature-induced at least partially radical formation starts the radical chain reaction leading to the formation of methanesulfonic acid:

HO—(SO.sub.2)—O.+CH.sub.4.fwdarw.H.sub.3C.+H.sub.2SO.sub.4

H.sub.3C.+SO.sub.3.fwdarw.H.sub.3C—(SO.sub.2)O.

H.sub.3C—(SO.sub.2)O.+CH.sub.4.fwdarw.H.sub.3C.+H.sub.3C—(SO.sub.2)OH

[0119] In another embodiment of this invention the present inventive process comprises at least partially other reaction pathways than solely a radical pathway, e.g. ionic pathways or combinations of radical and ionic pathways.

[0120] Optionally, purification step iii. may be carried out in more than two purification actions in order to further purify the MSA from step ii. and to further decrease e.g. the H.sub.2SO.sub.4 content in the purified MSA from step iii. A purification step is for example a distillation or crystallization.

[0121] Preferably, the process of this invention comprises a step iii. for purification of MSA obtained from step ii. It is further preferred that the purification step iii. is a single step distillation or a multi-step distillation.

[0122] It is further preferred that the purification step iii. is a crystallization and/or a solid-liquid separation. In an embodiment of the invention the purification step iii. is a combination of a crystallization and/or a solid-liquid separation with a distillation.

[0123] It is preferred that step i. is conducted in a reactor A, step ii. is conducted in a reactor B or a sequence of reactors and step iii. is conducted in a column or in a set of columns C, and whereas the reactor A, reactor(s) B and column(s) C are connected to conduct the process for the manufacturing of MSA continuously. If step iii. is carried out in a multi-step distillation at least the first purification step can be carried out in a simple vessel which can be stripped with a carrier gas or operated under vacuum as indicated below. Stripping by addition of a gaseous carrier is being regarded as a distillative or evaporative process.

[0124] Optionally, in an additional step iv., after MSA is obtained from step ii. or iii. respectively, MSA anhydride is provided for subsequent charging of reactor A with MSA anhydride.

[0125] Optionally, step iv. for providing MSA anhydride for subsequent charging of reactor A comprises a separated MSA anhydride manufacturing step after step iii. or MSA anhydride is provided for subsequent charging of reactor A by separation of MSA anhydride as side-product from step iii.

[0126] Preferably, prior to starting the synthesis/reaction sequence, the equipment used for steps i. to iv. is set under inert conditions, e.g. by rinsing with inert gases as nitrogen or argon, by repeated evacuation of the system and refilling the system with inter gases or by other means yielding the same effect. In particular, step i. and ii. should be carried out under inert conditions.

[0127] Preferably, the temperature in step i. is in the range from −5° C. to +25° C., more preferably in the range from −2° C. to +15° C. and most preferably in the range from 0° C. to 10° C., or any value between these values or ranges thereof. Preferably, the temperature in step ii. is in the range from 25° C. to 80° C., more preferably in the range from 30° C. to 70° C. and most preferably in the range from 40° C. to 60° C., or any value between these values or ranges thereof. Preferably, the temperature at the bottom of the column in step iii. is in the range from 30° C. to 220° C., more preferably in the range from 100° C. to 200° C., or any value between these values or ranges thereof. If the distillation in step iii. is carried out in two or more steps, the first step can be operated for example at temperatures in the range from 30° C. to 220° C., preferably in the range from 100° C. to 200° C., and more preferably in the range from 120° C. to 190° C., or any value between these values or ranges thereof. Alternatively, if more than one column is used, the set of columns are all operated in the range from 30° C. to 220° C. or 100° C. to 200° C. or 120° C. to 190° C. at the bottom.

[0128] Preferably, the pressure in step i. can be any pressure, preferably a pressure close to normal conditions or for example slightly increased pressures, in particular in the range from 0.5 bar to 10 bar, more preferably in the range from 0.8 bar to 5 bar and most preferably at about 1013 mbar or for example at slightly elevated pressure beyond 1013 mbar, e.g. 2 bar (absolute), or any value between these values or ranges thereof. The pressure in step ii. is preferably in the range from 10 bar to 150 bar, more preferably in the range from 20 bar to 100 bar, and most preferably in the range from 40 bar to 80 bar, or any value between these values or ranges thereof. The pressure in step iii. is preferably in the range from 2 mbar to 1000 mbar, more preferred in the range from 5 to 300 mbar, or any value between these values or ranges thereof. In an embodiment of this invention a flash or a series of flash installations is introduced between steps ii. and iii. to allow for single or stepwise adaptation from the pressure applied in step ii. to the pressure in step iii. and to reduce the amount of light boilers carried over from step ii. into step iii. If the distillation in step iii. is carried out in two or more steps, the first step can be operated at pressures in the range from 5 mbar to 1000 mbar, preferably in the range from 7 mbar to 200 mbar, and most preferably in the range from 10 mbar to 100 mbar or 10 mbar to 50 mbar, or any value between these values or ranges thereof. The second step can be carried out at a pressure between 0.1 and 20 mbar, preferably between 2 and 10 mbar. Alternatively, if more than one column is used, the set of columns are all operated in the range from 0.1 to 20 bar, preferably between 2 to 10 bar.

[0129] A further aspect of the invention relates to the use of an initiator composition comprising MSA, optionally sulfuric acid, optionally SO3 and/or a recycle stream from the bottom purge of the distillation of MSA comprising mainly MSA and H.sub.2SO.sub.4, MSA anhydride and aqueous H.sub.2O.sub.2 for the manufacturing of MSA, preferably by radical reaction (or partially radical reaction).

[0130] A further aspect of the invention relates to methane sulfonic acid (MSA), whereas after purification in step iii. the MSA content is above 98 wt-%, preferably in the range from 99.0 wt-% to 100 wt-% or from 99.5 wt-% to 100 wt-%, or any value between these values or ranges thereof. It is in particular preferred that after purification in step iii. the MSA content is about 99.6 wt-%, 99.7 wt-%, 99.8 wt-% or 99.9 wt-%. It is further preferred that after purification in step iii. the H.sub.2SO.sub.4 content is preferably about 200 ppm or lower, more preferably about 150 ppm or lower, even more preferably about 100 ppm or lower, and most preferably about 50 ppm or lower, or any value between these values or ranges thereof. It is in particular preferred that after purification in step iii. the sulfuric acid content is in the range from 0 ppm to 20 ppm, preferably in the range from 0 ppm to 15 ppm, more preferably in the range from 0 ppm to 10 ppm and most preferably in the range from 0 ppm to 5 ppm, or any value between these values or ranges thereof.

[0131] The same target values for the purified MSA after step iii. apply if purification is done via a crystallization step or a combination of distillation and crystallization.

[0132] If using a dedicated pressure swing absorption unit to provide purified methane according to the invention, use the “waste methane” at the outlet of the pressure swing absorption, which is enriched in ethane, propane, butanes and higher alkanes, alkenes or alkines as fuel to heat the MSA distillation sump via indirect heating, e.g. generate steam and use as heat carrier for a heat exchanger or heat oil as heat carrier for a heat exchanger.

[0133] It must be noted that as used herein, the singular forms “a”, “an”, and “the”, include plural references unless the context clearly indicates otherwise. Thus, for example, reference to “a reagent” includes one or more of such different reagents and reference to “the method” includes reference to equivalent steps and methods known to those of ordinary skill in the art that could be modified or substituted for the methods described herein.

[0134] Unless otherwise indicated, the term “at least” preceding a series of elements is to be understood to refer to every element in the series. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the present invention.

[0135] The term “and/or” wherever used herein includes the meaning of “and”, “or” and “all or any other combination of the elements connected by said term”.

[0136] The term “about” or “approximately” as used herein means within 20%, preferable within 10%, and more preferably within 5% of a given value or range. The term “about” or “approximately” as used herein also includes the exact respective values or ranges.

[0137] Throughout the specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step. When used herein the term “comprising” can be substituted with the term “containing” or “including” or sometimes when used herein with the term “having”.

[0138] When used herein “consisting of” excludes any element, step, or ingredient not specified in the claim element. When used herein, “consisting essentially of” does not exclude material or steps that do not materially affect the basic and novel characteristics of the claim.

[0139] Although the invention has been described with respect to specific embodiments and examples, it should be appreciated that other embodiments utilizing the concept of the present invention are possible without departing from the scope of the invention. The present invention is defined by the claimed elements, and any and all modifications, variations, or equivalents that fall within the true spirit and scope of the underlying principles.

EXAMPLES

[0140] Synthesis of Methanesulfonic Acid by Sulfonation of Methane—General Procedure

[0141] Sulfonation of methane was carried out in a 300 mL autoclave (material of construction HC-4) which is equipped with a glass liner, baffles (HC-4), a thermo-sleeve (HC-4) and a magnetic stirring bar (magnetic metal core with PTFE lining). Handling of sulfur trioxide and sulfur trioxide containing solutions (e.g. oleum) is carried out under inert conditions (N2 or Ar atmosphere) to avoid SO3-losses by formation of sulfuric acid.

[0142] In a typical experiment, a 250 mL round bottom flask is charged with a sulfur trioxide containing solution (e.g. oleum with 32 wt. % sulfur trioxide). Thereafter, the solution is cooled down to a temperature of 10-20° C. Subsequently, an aqueous H.sub.2O.sub.2 solution (e.g. 70 wt. %) is added slowly via immersed tube into the liquid under stirring. The mixture is transferred to the autoclave and the autoclave is quickly closed. After closing, the head space is repeatedly flushed with N2 to render the autoclave inert. After a pressure of 50-100 bar methane has been set, the temperature is slowly raised to 40-60° C. at a rate of 0.4-0.6° C./min causing an additional pressure increase. Examples of typical curves of pressure and temperature over the duration of the experiment are given in FIGS. 2-4. (A typical reactor set-up for an embodiment of the invention is shown in FIG. 1).

[0143] In the course of several hours the pressure drops by up to ca. 50 bar and plateaus. The residual pressure is released slowly and the liquid is recovered as crude product. The color ranges from pale-yellow to dark red depending on the quality of employed methane gas.

[0144] In order to show the range of typical side products, in some examples the crude product is characterized by .sup.1H— and .sup.13C-NMR spectroscopy (C.sub.6D.sub.6 was used in a capillary as the lock reference; device: Bruker Avance III HD 400 MHz; identification of main product and side products) Moreover all product mixes with significant methane conversion (indicated by the pressure drop) were characterized by acidimetry (crude product is diluted with H.sub.2O, determination of MSA- and H.sub.2SO.sub.4 content in wt. %), and measurement of the color index (Hazen scale; apparatus: LICO 500, Hach/Lang, upward limit 1000 Hazen).

[0145] The examples are meant to further explain effects related to the reaction of CH4 and SO3 in the synthesis step ii. The formation of the starter (step i.) is described as part of the overall synthesis sequence in one embodiment of the invention.

[0146] The calculation of MSA yields in the following examples considers only what happens in the synthesis reactor (unless explicitly noted otherwise).

[0147] The calculation of MSA yields is done as follows (unless otherwise mentioned).

Y(MSA based on SO3, given in %)=((MSA at the end of the reaction in mol)/(SO3 available for the reaction with CH4 in mol))×100

[0148] MSA at the end of the reaction is determined by weighing the content of the reactor after reaction, determining the MSA concentration by acidimetry in wt-%, multiplying these two values and converting them into mol MSA (output given in mol MSA formed during reaction and the mol SO3 converted to MSA are equivalent).

[0149] SO3 available for the reaction with CH4 is determined by the total weight of oleum introduced into the reactor—and thus the total amount of SO3—corrected by the amount of water in mol introduced via the H.sub.2O.sub.2 solution during formation of the starter which captures SO3 and forms H2SO4 (output given in mol).

[0150] Employed primary methane sources (CH.sub.4 99.5% and CH.sub.4 99.995%) are analyzed by gas chromatography. Ethane and propane are commercially available. Impurities in these gases are specified. Gases 4 and 7 were premixed. The compositions of the used gas mixtures are given in Table 1. (Methane pre PSA and post PSA are available commercially in gas bottles.)

TABLE-US-00001 TABLE 1 Gas composition of used gases Gas composition methane ethane propane other hydrocarbons nitrogen carbon dioxide (vol %) (vol %) (vol %) (vol %) (vol %) (vol %) 1 99.995 <2 ppm <2 ppm <10 ppm 2 99.649 225-227 ppm <2 ppm 22 ppm 3 99.500 322-324 ppm <2 ppm 31-32 ppm 4 97.939 0.906 0.251 0.794 0.110 5 97.507 0.446 0.124 1.869 0.054 6 99.409 0.227 0.063 0.265 0.037 7 98.700 0.010 0.005 1.270 8 96.995 2.999 <21 ppm 9 96.995 2.999 <22 ppm 10 <25 ppm 99.950  <375 ppm <40 ppm <5 ppm 11 99.950  <400 ppm <40 ppm <5 ppm

TABLE-US-00002 TABLE 2 Overview over yield and color index. Example Gas Yield Color index No. composition (%) (HAZEN) 1 1 90 ± 2 58 2 2 85 ± 2 102  3 3 90 ± 2 118  4 4  5 ± 2 out of scale 5 5 31 ± 2 out of scale 6 6 86 ± 2 85 7 7 94 ± 2 n.a. 8 8 — out of scale 9 9 — out of scale

Example 1

[0151] Sulfonation of methane was carried out according to the procedure described afore. 0.20 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 103.06 g oleum (32 wt. % SO.sub.3) under cooling to 11-12° C. and stirring. 93.09 g of the mixture were transferred into the autoclave. After rendering inert, a methane pressure of 100 bar was set. The purity of the employed methane gas was 99.995% (gas composition 1, cf. Table 1). Setting the temperature to 50° C. (at a rate of 0.4° C./min), the pressure increased to approx. 110 bar. After 5 h the pressure dropped by 26 bar. 97.25 g of a non-fuming pale-yellow liquid was recovered from the autoclave. A color index of 58 Hazen was measured. The methanesulfonic acid content was determined to be 31.8 wt. % corresponding to a yield of 90±2%. Via NMR the following side products could be identified: 0.01 wt. % H.sub.3C—(SO.sub.2)—OCH.sub.3 (methyl methanesulfonate), 0.07 wt. % H.sub.3CO—(SO.sub.2)—OH (methyl bisulfate), traces of HO—(SO.sub.2)—CH.sub.2—(SO.sub.2)—OH (methanedisulfonic acid).

[0152] Results are shown in FIG. 2.

Example 2

[0153] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 101.27 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 85.91 g of the mixture were transferred into the autoclave. After rendering inert, a pressure of 30 bar of gas 3 and 70 bar of gas 1 was applied for a total pressure of 100 bar. The composition of the employed gas is given in Table 1 (gas composition 2). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 111 bar. After 3 h the pressure dropped by 20 bar. 89.53 g of a non-fuming yellowish liquid was recovered from the autoclave. The methanesulfonic acid content was determined as 29.2 wt. % referring to a yield of 85±2%. A color index of 102 Hazen was obtained. Via NMR the following side products could be identified: 0.03 wt. % H.sub.3C—(SO.sub.2)—OCH.sub.3 (methyl methanesulfonate), 0.18 wt. % H.sub.3CO—(SO.sub.2)—OH (methyl bisulfate), 0.02 wt. %, HO—(SO.sub.2)—CH.sub.2—CH.sub.2—O—(SO.sub.2)—OH, <0.01 wt. % H.sub.3C—CH.sub.2—(SO.sub.2)—OH (ethanesulfonic acid), traces of HO—(SO.sub.2)—CH.sub.2—(SO.sub.2)—OH (methanedisulfonic acid) and HO—(SO.sub.2)—CH.sub.2—CH.sub.2—(SO.sub.2)—OH (ethanedisulfonic acid).

[0154] Results are shown in FIG. 3.

Example 3

[0155] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 100.93 g oleum (32 wt. % SO.sub.3) under cooling and stirring. 88.28 g of the mixture were transferred into the autoclave. After rendering inert, a methane pressure of 100 bar was set. The purity of the employed methane gas was 99.5% (gas composition 3, cf. Table 1). Setting the temperature to 50° C. (at a rate of 0.6° C./min), the pressure increased to approx. 111 bar. After 4 h the pressure dropped by 26 bar. 92.27 g of a non-fuming yellow liquid was recovered from the autoclave. The methanesulfonic acid content was determined as 30.8 wt. % referring to a yield of 90±2%. A color index of 110 Hazen was obtained. Via NMR the following side products could be identified: 0.02 wt. % H.sub.3C—(SO.sub.2)—OCH.sub.3 (methyl methanesulfonate), 0.17 wt. % H.sub.3CO—(SO.sub.2)—OH (methyl bisulfate), 0.03 wt. %, HO—(SO.sub.2)—CH.sub.2—CH.sub.2—O—(SO.sub.2)—OH, 0.01 wt. % H.sub.3C—CH.sub.2—(SO.sub.2)—OH (ethanesulfonic acid), traces of HO—(SO.sub.2)—CH.sub.2—(SO.sub.2)—OH (methanedisulfonic acid) and HO—(SO.sub.2)—CH.sub.2—CH.sub.2—(SO.sub.2)—OH (ethanedisulfonic acid).

[0156] Results are shown in FIG. 4.

Example 4—Comparative

[0157] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 98.93 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 86.53 g of the mixture were transferred into the autoclave. After rendering inert, a methane pressure of 100 bar was set. The purity of the employed methane gas is given in Table 1 (gas composition 4). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 110 bar. After 19 h the pressure dropped by about 18 bar. 85.29 g of a fuming redish liquid was recovered from the autoclave. The methanesulfonic acid content was determined as 1.4 wt. % referring to a yield of 5±2%. A color index in Hazen could not be obtained as the solution was out of HAZEN scale.

Example 5—Comparative

[0158] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 101.28 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 90.48 g of the mixture were transferred into the autoclave. After rendering inert, a nitrogen pressure of 1 bar remained. A pressure of 50 bar of gas 4 and 50 bar of gas 1 was applied for a total pressure of 101 bar. The composition of the employed gas mixture is given in Table 1 (gas composition 5). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 111 bar. After 19 h the pressure dropped by about 5 bar. 89.54 g of a fuming reddish liquid was recovered from the autoclave. The methanesulfonic acid content was determined as 11.2 wt. % referring to a yield of 31±2%. A color index in Hazen could not be obtained as the solution was out of HAZEN scale.

Example 6

[0159] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 100.39 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 85.34 g of the mixture were transferred into the autoclave. After rendering inert, a pressure of 25 bar of gas 4 and 75 bar of gas 1 was applied for a total pressure of 100 bar. The composition of the employed gas mixture is given in Table 1 (gas composition 6). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 112 bar. After 46 h the pressure dropped significantly. 88.57 g of a non-fuming slightly yellow liquid was recovered from the autoclave. The methanesulfonic acid content was determined as 29.8 wt. % referring to a yield of 86±2%. A color index of 85 Hazen was obtained.

Example 7

[0160] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 102.01 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 91.22 g of the mixture were transferred into the autoclave. After rendering inert, a pressure of 100 bar was set with gas 7. The composition of the employed gas is given in Table 1 (gas composition 7). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 110 bar. After 3.25 h the pressure dropped by about 26 bar. 94.10 g of a non-fuming slightly yellow liquid was recovered from the autoclave. The methanesulfonic acid content was determined as 32.9 wt. % referring to a yield of 94±2%.

Example 8—Comparative

[0161] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 99.27 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 88.87 g of the mixture were transferred into the autoclave. After rendering inert, an ethane pressure of 3 bar was applied (gas composition 10, Table 1), followed by addition of gas 1 (Table 1) up to a total pressure pressure of 100 bar. The composition of the employed gas is given in Table 1 (gas composition 8). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 112 bar. After 19 h the pressure dropped by about 0.8 bar. 87.6 g of a fuming, red liquid was recovered from the autoclave. The methanesulfonic acid content was not determined. A color index in Hazen could not be obtained as the solution was out of HAZEN scale.

Example 9—Comparative

[0162] Sulfonation of methane was carried out according to the procedure described afore. 0.34 mL H.sub.2O.sub.2 (aqueous solution, 70 wt. % H.sub.2O.sub.2) were added to 102.7 g oleum (32 wt. % SO.sub.3) under cooling to 12-16° C. and stirring. 91.62 g of the mixture were transferred into the autoclave. After rendering inert, a propane pressure of 3 bar (gas 11, Table 1) was applied, followed by addition of gas 1 (Table 1) up to a total pressure pressure of 100 bar. The composition of the employed gas is given in Table 1 (gas composition 9). Setting the temperature to 50° C. (at a rate of 0.5° C./min), the pressure increased to approx. 111 bar. After 18 h no further pressure drop was observed. 88.76 g of a fuming, orange-red liquid was recovered from the autoclave. The methanesulfonic acid content was not determined. A color index in Hazen could not be obtained as the solution was out of HAZEN scale.