CA1069679A - Oxidation of sulphur-containing compounds - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A process which comprises the oxidation of sul-phur-containing compounds by treating said sulphur-contain-ing compounds with an oxygen-containing gas in a medium possessing a pH of from about 8 to 14 in the presence of a catalyst system comprising a Group VIIB metal phthalocyanine and a Group VIII metal phthalocyanine.

Description

~069~;79 The oxidation of various sulphur-containing com-pounds is well-known in the prior art. The oxidation re-actions known in the art are mainly directed to the oxida-tion of mercaptans to disulphides and the oxidation of hy-drogen sulphide to sulphur. Various modes of operation havebeen set forth, however, most generally the oxidation reactions have been performed catalytically in an alkaline environment.
It has been shown that various catalystshave been utilised in the oxidation reactions, the most notable consisting of dif-ferent metal chelates such as metal phthalocyanines. The metalphthalocyanine catalysts have been shown to include cobalt phthalocyanine, vanadium phthalocyanine, iron phthalocyanine, copper phthalocyanine, nickel phthalocyanine, molybdenum phthal-ocyanine chromium phthalocyanine, tungsten phthalocyanine, magnesium phthalocyanine, platinum phthalocyanine, hafnium phthalocyanine, palladium phthalocyanine, etc. Further, the catalysts of the prior art have been shown to be used in an aqueous liquid-liquid form or in a solid form dispersed on a solid support.
The prior art has also disclosed the use of poly metalo phthalocyanines in the oxidation reactions. For example, U.S.
Patent No. 3,565,959 (by Takase et al, assigned to Nippon Oil Company Limited of Tokyo, Japan) teaches the use of, inter alia, poly iron-manganese phthalocyanine in a process for oxidising mercaptans to disulphides.
In contradistinction to the prior art, it has now been discovered that a catalyst system comprising a mixture of a Group VIIs phthalocyanine and a Group VIII phthalocyanine can be utilised in the oxidation of sulphur-containing compounds.

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106~679 Many sulphur-containing compounds, especially mercaptans and hydrogen sulphide, which are formed in many industrial processes or occur naturally in crude oil, must be convert-ed to other compounds before disposal as a result of environ-mental considerations. For example, hydrogen sulphide hasa high oxygen demand and accordingly will deprive marine life and other living organisms of oxygen needed for survival.
Also, most mercaptan compounds possess a pungent odour which is harmful and displeasing to the surrounding environment.
Previous metal phthalocyanine catalyst systems set forth in the prior art possess problems of hydrogen peroxide production which causes overoxidation of the sulphur-contain-ing compounds. The overoxidation of the sulphur-containing compounds presents problems of colour generation, which is highly undesirable in the treatment of petroleum charge stocks, and of consumption of caustic or ammonia, which is normally utilised in the oxidation of both mercaptans and hydrogen sul-phide. The utilisation of the present catalyst system will greatly reduce the production of hydrogen peroxide, and there-fore overoxidation of the entire system. The lack of over-oxidation will alleviate the presence of any side oxidation products which would create consumption of caustic and colour formation within the recovered charge stock. The utilisation of the present invention will also allow the refiner or manu-facturer a catalytic treating method which is more economicallyfeasible as a result of the eradication of any necessary subse-quent treatment steps to remove colour-generating compounds and the extended "use time" for the caustic medium of the various treatment processes. The above catalyst system will also create .: ' ' . . ~ .': :

new combinations of metal phthalocyanine catalytic compo-sitions of matter as a result of the two component system, therefore, different impregnation and dispersal effects can further be studied to maximise catalytic treatment conditions.
According to the invention there is provided a pro-cess for the oxidation of sulphur-containing compounds which comprises the treatment of said sulphur-containing compounds with an oxygen-containing gas in a medium possessing a pH of from 8 to 14 in the presence of a catalyst system comprising a Group VIIB metal phthalocyanine and a Group VIII metal phthalo-cyanine at oxidation conditions, and recOvering the resultant oxidized sulphur-containing compound.
The oxidation conditions of the present invention in-clude atemperature of from 0 to 500C and preferably from 50C

15 to 400 C and a pressure from 1 to 100 atmospheres.
The sulphur-containing compounds of the present inven-tion are present in either a pure form of sulphur-containing com-pounds or they may be intermixed in a petroleum charge stock, an - aqueous charge stream or an alkali-aqueous charge stream. The sulphur-containing compounds in a petroleum charge stock may be present as natural mercaptans in a crude oil charge stock in its natural condition. Such mercaptans will possess 1 to 19 carbon atoms. Other mercaptans which may also be present include aro-matic mercaptans such as thiophenol or substituted thiophenols.
It is also contemplated within the scope of this invention that the sulphur-containing compounds comprise hydrogen sulphide dis-solved in an aqueous or an aqueous-alkaline solution. Specific types of mercaptans which may be converted to disulphide material by the oxidation process of th~s invention wlll inolude methyl . ' .

1069f~79 mercaptan, ethyl mercaptàn, propyl mercaptan, etc., various mercaptobenzothiazoles, hydroxy mercaptans such as mercapto--ethanol, cysteine, aromatic mercaptans such as thiophenol, methyl-substituted thiophenol isomers, ethyl-substituted thio-phenol isomers, propyl-substituted thiophenol isomers, etc.
The present catalyst system may be present in a range of from 1 to 6 moles of the Group VIIB metal phthalocyanine per mole of the Group VIII metal phthalocyanine. The total catalyst system may be present in a weight percent relative to the en-tire reaction system of from .0001 to 10.00 weight percent.
The Group VIIB metal phthalocyanine will include manganese phthalocyanine and rhenium phthalocyanine, said phthalocyanine compounds may be present in a sulphonated or a carboxylated state. For example, the Group VIIB metal phthalocyanine may comprise the monosulphonate, the disulphonate, the trisulphonate,the tetrasulphonate, or the carboxylate. Suitable examples of Group VIII metal phthalocyanine compounds will comprise cobalt phthalocyanine, iron phthalocyanine, nickel phthalocyanine, palladium phthalocyanine, rhodium phthalocyanine, ruthenium phthalocyanine, osmium phthalocyanine, iridium phthalocyanine or platinum phthalocyanine where the Group VIII metal phthalocyanine may also be carboxylated or sulphonated. The catalyst comprising the Group VIIB metal phthalocyanine and Group VIII metal phthalo- -cyanine may also be present in the form of polymers of phthalo-cyanine. For example, the catalyst system may comprise either a polymer or monomer of manganese phthalocyanine tetrasulphonate together with either a polymer or monomer of cobalt phthalocyanine tetra~ulphonate.

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106967g In a preferred embodiment of this invention it is found that the catalyst system comprising the Group VII~ metal phthalocyanine and Group VIII metal phthalocyanine may be present in either an aqueous or liquid-liquid form or the catalyst sys-tem may be dispersed on a solid support such as alumina, silica,magnesia, thallia, zirconia, carbon, charcoal, Y-alumina, morde-nite, faujasite, etc. The solid supports may be impregnated with reduced forms of the phthalocyanine compounds.
The process of the present invention is effec~ted in a medium possessing a pH in a range of from 8 to 14. The medium which supplies the pH factor will comprise any alkaline material such as sodium hydroxide, potassium hydroxide, ammonia, pyridine, piperidine, picoline, lutidine, quinoline, pyrrole, indole, car-bazole, acridine, or any suitable quaternary ammonium compound such as tetrabutyl ammonium hydroxide, tetraamyl ammonium hydrox-ide, tetrapropyl ammonium methoxide, tetraamyl ammonium methoxide, diethyl amine, triethyl amine; however, the preferred alkaline medium will comprise either sodium hydroxide or ammonia, the sodium hydroxide being preferred when mercaptan removal is ef-fected and the ammonium being preferred when hydrogen sulphideremoval is effected. As hereinbefore set forth the pH range of the medium will be from 8 to 14. The preferred pH range will be 9 to 13. For example, when sodium hydroxide is utilised as the treatment medium of the present invention, a pH of from 11 to 13 will exist within the treatment system. However, when ammonia is used a pH of from 9 to 13 will be present in the treatment sys-tem~ It should also be noted that the treatment medium possessing a pH in the range of from 8 to 14 will be present in any system in which the catalyst is dispersed upon an inert support. The 1069~i79 treatment medium is present in the solid support system by either a continual fIow over the solid support or the treat-ment medium may be intermittently contacted with the solid support.
Treatment of the charge stock containing the sulphur-containing compounds may be effected in any suitable manner andmay be in a ~atch or continuous type process. The batch or continuous type process may both comprise either the solid bed treating or the liquid-liquid treating process. In a batch pro-cess the charge stock containing a sulphur-containing compound is introduced into the oxidation zone containing the novel catalytic system of the present invention, the treatment medium possessing a pH in the range of from 8 to 14 and air is introduced therein or passed therethrough. Preferably the oxidation zone is equipped with suitable stirrers or other mixing device to obtain intimate mixing. In a continuous process the treatment medium may contain the novel catalytic system of the present invention comprising a Group VIIB metal phthalocyanine and a Group VIII metal phthalo-cyanine, all of which is passed countercurrently or concurrently with the charge stock containing the sulphur-containing compounds in the presence of a continuous stream of air or oxygen. In a mixed type process the oxidation zone contains the treatment mediun phthalocyanine catalyst system and the charge stock and air are passed continuously therethrough and removed, generally from the upper portion of the oxidation zone. In cases of treating charge stocks containing mercaptan compounds, the resultant disulphide oxidation products may be recovered from the resultant oxidation zone effluent by any method known in the art or the disulphides may be allowed to continue through other petroleum process treat-ing units as a harmless sulphur-containing compound. In a case ~7--.

11)69679 in which the charge stock comprises hydrogen sulphide, the resultant sulphur product may be separated by any method known to the art and utilised in the chemical industry as a pure sul-phur compound.
EXAMPLE I
In this example 0.98 grams of thiophenol, 50 ml of isooctane, 50 ml of 8% sodium hydroxide, 0.008 grams of potassium cyanide and .008 grams of cobalt phthalocyanine tetrasulphonate were placed in a 100 ml-round bottom flask containing a magnetic stirrer and a means of oxygen entry and uptake measurement. The oxygen uptake measurement is defined as the amount of oxygen con-sumed in the oxidation of the thiophenol. The desired effect is to minimise the quantity of oxygen uptake, thereby indicating the diminishment of the quantity of hydrogen peroxide (which is a par-tial reduction product of oxygen and is responsible for overoxi-dation). The potassium cyanide was added because the amount of hydrogen peroxide is maximised when the cyanide ion is present.
In this manner, it is easier to compare small increments~of hy-drogen peroxide formation. The flask was maintained at a tem-perature of 20 C and a pressure of l atmosphere as afforded bythe introduction of oxygen to the oxidation flask for a period of time comprising l9 minutes, which was the approximate 100%
oxidation time. The oxygen uptake was measured at the end of this period of time, said oxygen uptake being 80.5 ml/gram of thiophenol at standard pressure and temperature.
EXA~æLE II
In this example 0.73 grams of thiophenol, 50 ml of isooctane, 50 ml of 8~ sodium hydroxide,0.008 grams of potassium cyanide and 0.034 grams of cobalt phthalocyanine tetrasulphonate :~, ~069679 were placed in a 100 ml-round bottom flask containing a mag-netic stirrer and a means of oxygen entry and uptake measure-ment. The flask was maintained at a temperature of 2QC and a pressure of 1 atmosphere as afforded by the introduction of oxy-gen to the oxidation flask for a period of time comprising 13 minutes, which was the approximate 100% oxidation time. The oxygen uptake ~as measured at the end of this period of time, said oxygen uptake being 71.8 ml/grams of thiophenol at stan-dard pressure and temperature.
EXAMPLE III
In this example 1.00 grams of thiophenol, 50 ml o iso-octane, 50 ml of 8% sodium hydroxide, 0.008 grams of potassium cyan~ide and a catalyst system comprising 0.008 grams of cobalt phthalocyanine tetrasulphonate and 0.026 grams of manganese phthalocyanine tetrasul~honate (a 3:1 mole ratio of manganese species to cobalt species) was added to a 100 ml-round bottom flask containing a magnetic stirrer and a means of oxygen entry and uptake measurement. The oxygen uptake is defined as set forth in Example I. The oxidation flask was maintained at the conditions of pressure and temperature of Examples I and II for a period of time comprising 15 minutes, which was the approxi-mate 100% oxidation time. The oxygen uptake was measured at the end of this period of time, said oxygen uptake being 42.2 ml/gram of thiophenol at standard pressure and temperature.
The unexpected results of the present invention may be cogently seen in a comparison of Example III with Examples I
and II. In Example III a catalyst system comprising a Group VIIB metal phthalocyanine and a Group VIII metal phthalocyanine was utilized in comparison to the Group VIII metal phthalocyanine _g_ , 10696~9 of Examples I and II. The result of the different catalyst sys-tem in Example III was the oxygen uptake of only 42.2 ml/~ram of thiophenol at STP in comparison with the oxygen uptake of 80.5 ml/gram of thiophenol at STP of Example I and the 71.8 ml/gram of thiophenol at STP of Example II. The difference in the respective numbers shows that less overoxidation occurred in Example III, since substantially less hydrogen peroxide was present than in the Examples I and II, which utilized a cata-lyst known in the art.
EXAMPLE IV
In this example l.ll grams of thiophenol, 50 ml of isooctane, S0 ml of 8~ sodium hydroxide, 0.008 grams of potas-sium cyanide and a catalyst system comprising 0.008 grams of cobalt phthalocyanine tetrasulphonate and 0.008 grams of manga-nese phthalocyanine tetrasulphonate (a 1:1 mole ratio of the manganese species to the cobalt species) was added to a lO0 ml-round bottom flask containing a magnetic stirrer and a means of oxygen entry and uptake measurement. The oxidation flask was maintained at the conditions of pressure and temper-ature of Examples I, II and III for a period of time compris-ing 17 minutes, which was the approximate 100% oxidation time.
The oxygen uptake was measured at the end of this period of time, said oxygen uptake being 50.4 ml/gram of thiophenol at standard pressure and temperature.
It should be noted that in a comparison of Example -IV to Example III that the amount of hydrogen peroxide was increased with the change from the 3:1 metal species ratio to the 1:1 metal species ratio. However, in the comparison of Example IV to Examples I and II it can be seen that the amount --10-- . -.

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~ Q6 of oxygen uptake, or hydrogen peroxide formation, the relative value was still decreased using the 1:1 metal species ratio in contrast to the known catalytic metals of Examples I and II
which showed an oxygen uptake of 80.5 ml/gram of thiophenol at STP for Example I and 71.8 ml/gram of thiophenol at STP for Example II.
EXAMPLE V
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In this example 1.50 grams of thiophenol, 50 ml of :
isooctane, 50 ml of 8% sodium hydroxide, 0.008 grams of potas- :
sium cyanide and a catalyst system comprising 0.014 grams of cobalt phthalocyanine tetrasulphonate and 0.007 grams of man-ganese phthalocyanine disulphonate (a 2:1 mole ratio of cobalt species to the manganese species) was added to a 100 ml-round bottom flask containing a magnetic stirrer and a means of oxy-gen entry and uptake measurement. It should be noted in this experiment that a disulphonate of one metal of the two-compon-ent system is utilized in conjunction with a tetrasulphonated metal of the two-component system in contrast to the previous examples which have all compared the metal tetrasulphonates in combination with each other. The oxidation flask was maintained at a temperature of 20C. and a pressure of 1 atmosphere as af-forded by the introduction of oxygen to the oxidation flask for : a period of time comprising 23 minutes, which was the approxim-ate 100~ oxidation time. The oxygen uptake was measured at the : ~ end of this period of time, said oxygen uptake being 53.5 ml/
gram of thiophenol at STP
It should be noted that a comparison of Example V
;with Examples I and II show a decrease in the hydrogen perox-:~ ide formed (lower oxygen uptake values) utilizing the Group VIIB metal disulphonate in conjunction with the Group VIII metal tetrasulphonate (cobalt phthalocyanine tetrasulphonate), which was previously known in the art.
EXAMPLE VI
In this example 1.54 grams of thiophenol, 20 ml of isooctane, 50 ml of 8~ sodium hydroxide, and 0.05 grams of co-balt phthalocyanine tetrasulphonate dispersed on 50.00 grams of Nuchar WA (a charcoal compound produced under the trademark Nuchar WA) was added to a 100 ml-round bottom flask containing a magnetic stirrer and a means of oxygen entry and uptake mea-surement. The oxidation flask was maintained at conditions of 20~ and a pressure of 1 atmosphere for a period of time com- ~ -prising 30 minutes, which was the approximate 100~ oxidation time. The oxygen uptake at the end of this period of time was measured, said oxygen uptake being 62.7 ml/gram of thiophenol at STP.
It should be noted that this example is included within the specification to show the increased advantage of treat-ing asulphur-containing compound with the bimetallic catalyst sys-tem of Example VII, this example, Example VI, utilizing only the monometallic catalyst system which was previously known in the art. -EXAMPLE VII
In this example 1.53 grams of thiophenol, 20 ml of isooctane, 50 ml of 8% sodium hydroxide, 0.008 grams of potas-sium cyanide and a catalyst system comprising 0.90 grams of -manganese phthalocyaninetetrasulphonate and 0.16 grams of co-balt phthalocyanine tetrasulphonate dispersed on 45.00 grams of charcoal was added to a 100 ml-round bottom flask containing 1~696 ~ 9 a magnetic stirrer and a means of oxvqen entry and uptake mea-surement. The oxidation flask was maintained at the conditions of temperature and pressure of experiment VI for a period of time comprising 42.5 minutes which was the approximate lO0~
oxidation time. The oxygen uptake was measured at the end of this period of time, said oxygen uptake being 48.0 ml/gram of thiophenol at STP.
It should be noted that a comparison of Example VI
with Example VII will show a decrease in the amount of oxygen '0 uptake from 62.7 ml/gram of thiophenol at STP of Example VI to the 48.0 ml/gram of thiophenol at STP oxygen uptake of Example VII. The decrease in the oxygen uptake as hereinbefore set forth indicates the lower amount of hydrogen peroxide present in Example VII, thereby alleviating problems of caustic use and colour generation.
EXAMPLE VIII
In this example 1.66 grams of methyl mercaptan, 0.010 grams of potassium cyanide in a vaporous phase and a catalyst system comprising 0.50 grams of rhenium phthalocya-nine disulphonate and 0.50 grams of ruthenium phthalocyanine tetrasulphonate dispersed on 25.6 grams of alumina is added to a lO0 ml-round bottom flask containin~ a medium comprising tetrabutyl ammonium hydroxide, a magnetic stirrer and a means of air entry and air uptake measurement. The oxidation flask is maintained at oxidation conditions of 150C. and a pressure of S atmospheres as afforded by the introduction of air to the reaction system for a period of time comprising 15 minutes, which is the approximate 100% oxidation time of the methyl mer-captan. The air uptake is measured at the end of this period ~1 069679 of time, said air uptake being equal to an amount less than that of a controlled standardized example utilizing only the rhenium phthalocyanine disulphonate.
EXAMPLE IX
In this-example 0.52 grams of sodium sulphide, 50 ml of 4~ sodium hydroxide and 0.10 grams of cobalt phthalocy-anine tetrasulphonate was added to a 100 ml-round bottom flask containing a magnetic stirrer and a means of oxygen entry and uptake measurement. The oxidation flask was maintained at ox-idation conditions of 20C. and a pressure of 1 atmosphere as afforded by the introduction of oxygen to the reaction system for a period of time comprising approximately 130 minutes, which was the approximate 100% oxidation time. The oxygen uptake was measured at the end of this time, said oxygen uptake being 183.0 ml/gram sulphide at STP. It should be noted that the purpose of this example was to compare the monometallic catalyst system known to the art of this example with the hereinafter set forth Example X which discloses the unexpected utilizing the two-component cat-alyst system.
EXAMPLE X
In this example 0.53 grams of sodium sulphide, which was partially converted to hydrogen sulphide before oxidation, 50 ml of 4~ sodium hydroxide, 0.10 grams of cobalt phthalocya-nine tetrasulphonate and 0.30 grams of manganese phthalocyanine tetrasulphonate (a 3:1 mole ratio of manganese species to cobalt species) ~as added to a lOQ ml-round bottom flask containing a magnetic stirrer and a means of oxygen entry and uptake measure-ment. The oxidation flask was maintained at the same physical conditions of Example IX for a period of time comprising 125 .. . .. . . .. . .. . . . .... . . . . .

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minutes, which was the approximate 100% oxidation time. The oxygen uptake was measured at the end of this period of time, said oxygen uptake being 157.0 ml/gram sulphide at STP.
It can be seen as a comparison of Examples IX and X that the catalyst system of the present invention provided unexpected results in the fact that less oxygen uptake was re-corded utilizing the two-component catalyst systems. However, it should be noted that in the case of the hydro~en sulphide the decreased amount of oxygen uptake does not mean less for-mation of hydrogen peroxide as in the case of the oxidation of the thiophenol or mercaptan compound. The smaller the oxygen uptake of the example, the smaller the quantity of thiosulphate production from the oxidation of the sodium sulphide and the more sulphur.
EXAMPLE XI
In this example a catalyst comprising 1.1 grams of manganese phthalocyanine tetrasulphonate and O.lS grams of co-balt phthalocyanine tetrasulphonate on 45 grams of Darco 12 x 20 (a tradename for an activated charcoal compound sold under the name Darco 12 x 20) was prepared and utilized for the ox-idation of a charge stock comprising a liquid feed of 5.63 grams of sulphur as ammonium sulphide per hour (this sulphur being derived from hydrogen sulphide), and 0.73 grams of am-monium thiosulphate per hour for a total of 6.36 grams of sul-phur per hour. The temperature was maintained at 52C. and the pressure was maintained at 5 atmospheres, circulation of charge was at a liquid hourly space velocity (LHSV) of 1.0 with a 90% stoichiometric quantity of air. The resultant oxidation product was recovered, analyzed and found to contain only 0.72 grams of sulphur as ammonium thiosulphate, said result being unexpected in the fact that an experiment utilizing a catalyst known to the art would have resulted in the conversion of 7~14%
of the ammonium sulphide to ammonium thiosulphate. The oxida-tion product also indicates a 69.6 percent conversion of ammo-nium sulphide to ammonium polysulphide. It can be seen from the treatment of the two-component catalvtic system of the pres-ent invention that the amount of thiosulphate compound was dras-tically reduced in the presence of the novel catalyst system of the present invention.
EXAMPLE XII
In this example a comparison is made between a poly metalo phthalocyanine catalyst made in accordance with the teach-in~ of U. S. Patent No. 3,565,959 and the present catalyst sys-~ tem which comprises a mixture of two mono metallic phthalocya-nines.
A polyiron-manganese phthalocyanine catalyst was pre-pared by admixing and reacting 0.1 mole of pyromellitic acid with l.0 mole of urea, 0.025 mole of ferric chloride and 0.075 mole of manganese dichloride, the reaction mixture beinq heated at 160C. for 2 hours substantially in accordance with the method of 3,565,959. The manganese dichloride and ferric chloride were employed in a 3:1 mole ratio to provide a polyiron-manganese phthalocyanine catalyst containing manganese and iron in sub-stantially the same mole ratio as employed in the catalyst sys-tem of the present invention. In addition, a catalyst system was prepared pursuant to our method as described in the pres- -ent specification. Thus,.0081 grams of sulphonated manganese phthalocyanine was admixed with .0240 grams of sulphonated iron :.: :

106967'9 phthalocyanine to provide a mixture of said phthalocyanines in substantially a 3:1 mole ratio.
The last described iron phthalocyanine-manganese phthalocyanine system, as well as the first described poly-iron-manganese phthalocyanine catalyst of 3,565,959, was sub-jected to a comparative evaluation with respect to the over-oxidation tendencies of the catalyst by the method described in the present specification. This method determines how much side-product hydrogen peroxide is formed while oxidizing a small charge oE thiophenol to diphenyl disulphide. It also determines to what extent the thiophenol is overoxidized. sasically, the method consists of measuring the total oxygen uptake durinq the thiophenol oxidation. Thus, in each case, 1.25 grams of thio-phenol, 20 milliliters of isooctane, 50 milliliters of 8~ sodi-um hydroxide, 0.008 grams of potassium cyanide, and Q.034 grams of catalyst were placed in a lO0 milliliter round hotto~ed flask containing a magnetic stirrer and a means of oxygen entry and measurement of oxygen uptake. The flask was maintained at a temperature of 20C. and at a pressure of l atmosphere as af-forded by the introduction of oxygen to the oxidation flask until oxidation is completed. The oxygen uptake was measured at the end of the period required to effect 100~ oXidation of the thiophenol, the oxygen uptake being 62 milliliters per gram with respect to the catalyst of U. S. Patent No. 3,565,959, and 53.5 milliliters per gram with respect to our catalyst, indicat-ing substantial overoxidation by the 3,565,959 catalyst as com-pared to our catalyst.
This example, therefore, clearly demonstrates a pat-entable improvement over U. S. Patent No. 3,565,959, particular-ly as evidenced by the better selectivity with respect to the . . . ~ . . .
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oxidation of sulphur-containing compounds to minimize overoxid-ation to hydrogen peroxide and the resultant formation of unde-sirable side products.

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the oxidation of sulphur-contain-ing compounds which comprises the treatment of said sulphur-containing compounds with an oxygen-containing gas in a med-ium possessing a pH of from 8 to 14 in the presence of a cat-alyst system comprising a Group VIIB metal phthalocyanine and a Group VIII metal phthalocyanine at oxidation conditions, and recovering the resultant oxidized sulphur-containing compound.

2. The process of Claim 1 wherein the oxidation con-ditions include a temperature of from 0° to 500°C. and a pres-sure of from 1 to 100 atmospheres.

3. The process of Claim 1 wherein the catalyst system comprises from 1 to 6 mol of the Group VIIB metal phthalo-cyanine per mol of the Group VIII metal phthalocyanine.

4. The process of Claim 1 wherein the sulphur-contain-ing compound is a mercaptan.

5. The process of Claim 4 wherein the mercaptan is selected from methyl mercaptan, propyl mercaptan, and thio-phenol.

6. The process of any of Claims 1 to 3 wherein the sulphur-containing compound is hydrogen sulphide.

7. The process of any of Claims 1 to 3 wherein the oxygen-containing gas is oxygen or air.

8. The process of any of Claims 1 to 3 wherein the Group VIIB metal is manganese or rhenium.

9. The process of any of Claims 1 to 3 wherein the Group VIII metal is selected from ruthenium, iridium, cobalt, nickel, and iron.

10. The process of Claim 1 wherein the catalyst system is dispersed on a solid support.

11. The process of Claim 10 wherein the solid sup-port is carbon or Y-alumina.

12. The process of any of Claims 1 to 3 wherein the medium comprises sodium hydroxide or ammonia or a quaternary ammonium compound.