Title of Invention	"A PROCESS FOR LIQUID-LIQUID SWEETENING OF LIGHTER PETROLEUM DISTILLATES USING METAL PHTHALOCYANINE SULPHONAMIDE CATALYST"
Abstract	The present invention relates to a process for liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst. In the process liquid-liquid sweetening of lighter petroleum distillates like pentanes, lighter straight run naphtha (LSRN), FCC cracked naphtha and gasoline is carried out comprising of mixing sour light petroleum distillates, alkali solution containing metal phthalocyanine sulphonamide catalyst in presence of air, whereby the mercaptans present in the light petroleum distillates are oxidized to disulphides, which being hydrocarbon soluble goes with the sweetened petroleum distillates, and the alkali solution containing is recalculated.

Title of Invention

"A PROCESS FOR LIQUID-LIQUID SWEETENING OF LIGHTER PETROLEUM DISTILLATES USING METAL PHTHALOCYANINE SULPHONAMIDE CATALYST"

Abstract

The present invention relates to a process for liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst. In the process liquid-liquid sweetening of lighter petroleum distillates like pentanes, lighter straight run naphtha (LSRN), FCC cracked naphtha and gasoline is carried out comprising of mixing sour light petroleum distillates, alkali solution containing metal phthalocyanine sulphonamide catalyst in presence of air, whereby the mercaptans present in the light petroleum distillates are oxidized to disulphides, which being hydrocarbon soluble goes with the sweetened petroleum distillates, and the alkali solution containing is recalculated.

Full Text	The present invention relates to a process for liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst. Particularly, the invention relates to a procef; for liquid-liquid sweetening of lighter petroleum distillates like pentanes, lighter straight run naphtha (LSRN), FCC cracked naphtha and gasoline, comprising of mixing sour light petroleum distillates , alkali solution containing metal phthalocyanine sulphonamide catalyst in presence of air, whereby the mercaptans present in the light petroleum distillates are oxidized to disulphides, which being hydrocarbon soluble goes with the sweetened petroleum distillates, and the alkali solution containing catalyst is recirculated. Metal phthalocyanine sulphonamide catalyst has been prepared by a procedure as described and disclosed in our copending Indian patent application No 1032/DEL/2000. It is known that the presence of mercaptans in the petroleum products like LPG, naphtha, gasoline, keiosene, ATF etc is highly undesirable due to their foul odour and highly corrosive nature. These are also poisonous to the catalysts and adversely affect the performance of tetraethyl lead as octane booster. Although there are several processes known for the removal of mercaptans from petroleum products, the most common practice is to oxidize the mercaptans present, to less deleterious disulphides with air in the presence of a catalyst. Generally, the lower mercaptans present in LPG, pentanes, LSRN and light thermally cracked naphtha are first extracted in alkali solution and then oxidized to disulphides with air in the presence of a catalyst. The disulphides, being insoluble in alkali solution is separated out from the top and the alkali is regenerated. In the liquid-liquid sweetening the lower mercaptans present in petroleum products like pentanes, LSRN, FCC cracked naphtha etc are converted to disulphides by direct oxidation with air in the presence of alkali solution and catalyst. The higher molecular weight mercaptans present in petroleum products like heavy naphtha, FCC gasoline, ATF and kerosene are oxidized to disulphides with air in a fixed bed reactor containing catalyst impregnated on a suitable support like activated carbon (Catal. Rev. Sci. Eng. 35(4), 571-609, 1993). It is also well known that the phthalocyanines of the metals like cobalt, iron, manganese, molybdenum and vanadium catalyze the oxidation of mercaptans to disulphides in alkaline medium. Among these cobalt and vanadium phthalocyanines are preferred. As the metal phthalocyanines are not soluble in aqueous medium, for improved catalytic activity their derivatives like sulphonated and carboxylated metal phthalocyanines are used as catalyst for sweetening of petroleum fractions. For example use of cobalt phthalocyanine monosulphonate as the catalyst in the fixed bed sweetening of various petroleum products (US Patents No. 3,371,031; 4,009,120; 4,207,173; 4,028,269; 4,087,378; 4,141,819; 4,121,998; 4,124,494; 4,124,531) and cobalt phthalocyanine disulphoante (US Patent No. 4, 250, 022), tetra sulphonate (US Patent No. 2,622,763) and the mixture thereof (US Patent No. 4,248,694) as catalysts for liquid-liquid sweetening and alkali regeneration in mercaptan extraction of light petroleum distillates has been reported. The use of phenoxy substituted cobalt phthalocyanine as sweetening catalyst (Ger Offen 3,816, 952), cobalt and vanadium chelates of 2, 9, 16, 23-tetrakis (3,4-dicarboxybenzoyl) phthalocyanine as effective catalyst for both homogeneous and fixed bed mercaptan oxidation (Ger Offen 2, 757, 476; Fr. Demande 2,375,201) and cobalt, vanadium chelates of tetrapyridinoporphyrazine as active catalysts for sweetening of sour petroleum distillates (Ger Offen 2,441, 648) has also been reported. It is well known that the catalysts used for the liquid-liquid sweetening of lighter petroleum distillates like pentanes, light straight run naphtha (LSRN), FCC cracked naphtha and gasoline are di-, tri-and tetra sulphonates of metal phthalocyanines particularly those of cobalt and vanadium phthalocyanines; cobalt phthalocyanine sulphonates being specially preferred. The cobalt phthalocyanine sulphonates, differ in activity and in their solubility characteristics depending upon the number of sulphonate functionalities leading to problems in their use as catalysts. Cobalt phthalocyanine disulphonate a commonly used catalyst in sweetening of light petroleum distillates is extremely dusty in the dry fine powder form and causes handling problem. To overcome this problem cobalt phthalocyanine disulphonate is admixed with Water and commonly used as a slurry. However, with insufficient mixing the cobalt phthalocyanine disulphonate precipitates out from the slurry. Moreover, even if the slurry is mixed sufficiently, it retains the cobalt phthalocyanine disulphonate in suspension for a particular length of time only, beyond which the slurry becomes extremely viscous and may form gel, making it very difficult to remove the material from packaging. Cobalt phthalocyanine tetrasulphonate, on the other hand, is highly soluble in water and its use can eliminate precipitation and gel forming problems associated with the use of cobalt phthalocyanine disulphonate. However, it is reported that cobalt pthalocyanine tetrasulphonate has lower catalytic activity than cobalt phthalocyanine disulphonate (US patent 4, 885,268). In one of our application 1032/del/2000 we reported an improved process for the preparation of metal phthalocyanine sulphonamide catalyst useful for sweetening and obviates the drawback as detailed above. The main objective of the present invention is to provide a process for liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst, which obviates the drawbacks as details above. Accordingly the present invention provides a process for the liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst which comprises mixing the sour petroleum distillates selected from pentanes, light straight run naphtha (LSRN), Fluid catalytic cracked naphtha and gasoline with an aqueous solution of alkali metal hydroxide such as herein described in the concentration ranging from 1 wt% to 50 wt% containing metal phthalocyanine sulphonamide catalyst in the concentration ranging from 5 to 4000 ppmw in the presence of air, oxygen or any other oxygen containing gas at a temperature ranging between 25°C to 90°C and pressure ranging between 1 kg/cm2 to 60 kg/cm2, thereby converting the mercaptans present in the lighter petroleum distillates to corresponding hydrocarbon soluble disulphides, separating the sweetened petroleum distillates from alkali solution containing catalyst by known methods and recalculating the alkali solution containing catalyst for further sweetening process. In an embodiment of the present invention the metal phthalocyanine sulphonamide used is selected from the group consisting of cobalt, manganese, nickel, iron, vanadium phthalocyanine sulphonamide and their N-substiruted sulphonamide derivatives most preferably cobalt phthalocyanine sulphonamide. In an embodiment of the present invention the aqueous solution of alkali metal hydroxides used is selected from group consisting of aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide most preferably aqueous solution of sodium and potassium hydroxide. In another embodiment of the present invention the concentration of aqueous solution of alkali metal hydroxide used is preferably in the range 4 % to 25 % by weight. In yet another embodiment of the present invention the metal phthalocyanine sulphonamide catalyst used is preferably in the concentration range between 10-1000 ppniw. In still another embodiment of the present invention the liquid-liquid sweetening is preferably effected in the presence of air. In still another embodiment of the present invention the liquid-liquid sweetening is preferably effected at a temperature ranging between 20°C to 60°C. In still another embodiment of the present invention the liquid-liquid sweetening is effected preferably at 1 kg/cm2 to 20 kg/cm2. In an embodiment of the present invention the liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst is used for treating petroleum fractions with mercaptan sulphur content in the range 10 ppmw to 20,000 ppmw. In yet another embodiment of the present invention liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst can be effected in batch or continuous manner. Process Description In the liquid-liquid sweetening process herein contemplated, the mercaptan containing (sour) lighter petroleum distillates like pentanes, light straight run naphtha (LSRN), FCC cracked naphtha and gasoline are mixed in continuous or batch manner with aqueous solution of alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, containing cobalt phthalocyanine sulphonamide catalyst, and air or any other oxygen containing gas. The mercaptans present in the light petroleum distillates are oxidized to corresponding disulphides by oxygen present in air in presence of catalyst and alkali. The disulphides thus formed being hydrocarbon soluble goes with the sweetened petroleum distillates and the alkali solution containing catalyst is recirculated after gravity separation. The sweetening process is effected with the metal phthalocyanine sulphonamide catalyst like cobalt, manganese, nickel, iron and vanadium phthalocyanine sulphonamide and their N-substituted derivatives, the preferred catalyst is cobalt phthalocyanine sulphonamide. The catalyst is used in the concentration 5 to 4000 ppmw related to alkali solution, the preferred range is 10 - 1000 ppmw. The aqueous solution of alkali metal hydroxide used in this sweetening process is aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide preferably aqueous solution of sodium and potassium hydroxide. The concentration of aqueous solution of alkali metal hydroxide used is 1 % to 50 % the preferably 4 % to 25 %. This liquid-liquid sweetening process is effected at pressure ranging from atmospheric to 60 kg/cm2 preferred range being 1 to 20 kg/cm2. Similarly the process is effected at the temperature ambient to 90°C, preferably 20°C to 60°C. The process is effected by air, oxygen or any other oxygen containing gas, air being especially preferred. The following examples are given by way of illustration and therefore, should not be construed to line to the scope of the invention. Example 1 Preparation of Cobalt Phthalocyanine Sulphonamide Catalyst as described in our Indian Patent Application No. 1032/Del/2000 Preparation of Cobalt Phthalocyanine Sulphonyl Chloride For the preparation of cobalt phthalocyanine sulphonyl chloride, 30 parts by weight of cobalt phthalocyanine were slowly added with stirring to 315 parts by weight of chlorosulphonic acid. The reaction mixture was heated to about 75°C in one hour and from 75°C to about 130°C in 1.5 hours by controlling the heating rate, with constant stirring. The reaction mixture, after maintaining 130-135°C for additional 4 hours, was cooled to 60-65°C, and then 123 parts of thionyl chloride were slowly added. The whole contents were heated to 79°C and maintained at this temperature for one hour. The reaction product was cooled to room temperature and slowly added to crushed ice, keeping the temperature preferably below 5°C. The precipitated cobalt phthalocyanine sulphonyl chloride was filtered and washed thoroughly with cold water. The filtered cake was stored wet at 0°C till further processing. Preparation of Cobalt Phthalocyanine Sulphonamide In a typical preparation of cobalt phthalocyanine sulphonamides, total wet cake of cobalt phthalocyanine sulphonyl chloride, obtained was dispersed in 900 parts of ice water and 190 parts of methanol added to get homogeneous dispersion. The reaction mixture was stirred at 5-8°C and ammonia gas was passed till the mixture was fairly alkaline (pH 8-9). Pyridine (1.2 parts) was then added and the mixture stirred at room temperature for 20 minutes. This was followed by addition of 6 parts of 10% sodium hydroxide solution followed by stirring the reaction mixture for 40 minutes at room temperature. The contents were then heated to 80°C and after maintaining at this temperature for 1 hour, cooled to room temperature and poured over a mixture of ice and concentrated hydrochloric acid keeping the pH fairly acidic (2-3). The precipitated cobalt phthalocyanine tetrasulphonamide was filtered, washed thoroughly with cold water and dried in vacuum oven to yield 44 gms of the product. The FAB mass spectral analysis of the sulphonamide obtained using cobalt phthalocyanine as the starting material showed the presence of tetra sulphonamide as the major isomer, followed by trisulphonamide and disulphonamide isomers. Example 2 Liquid-Liquid Sweetening The experimental set-up used consisted of a 250 ml round bottom flask, fitted with a mechanical stirrer with teflon blade, a gas inlet tube and a condenser. The feed was prepared by adding standard 1-hexanethiol to light naphtha (b.p. 60-90°C) and its mercaptan sulphur content was estimated by UOP method 163-89. The catalyst solution was prepared by adding calculated amount of cobalt phthalocyanine sulphonamide to 7 % aqueous solution of sodium hydroxide. The prepared feed (100 ml) was taken in the RB flask and 7 % aqueous solution of sodium hydroxide containing catalyst was added to it. The stirrer (speed 1600 rpm) and air flow(rate about 1.0 lit/min) were then started. The reaction was carried out at room temperature (25-35°C) for 10 min. The reaction mass was then transferred to a separating funnel and the treated naphtha was separated. The aqueous sodium hydroxide solution layer containing the catalyst was reused with fresh naphtha (100 ml) doped with 1-hexanethiol. The catalyst solution was thus repeatedly used number of times. The mercaptan sulphur content of the treated naphtha obtained after each experiment was estimated by UOP method 163-89. Results are given in Table-1. Table-1 Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min Volume of 7 % aqueous solution of sodium hydroxide containing catalyst taken, ml Air flow rate at NTP, litres/min480 100 300 10 20 0.95-1.05 (Table Removed) Example 3 Liquid-Liquid Sweetening Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-2. Table-2 Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min Volume of 7 % aqueous solution of sodium hydroxide containing catalyst taken, ml Air flow rate at NTP, litres/min 1100 100 300 10 20 0.95-1.05 (Table Removed) Example 4 Liquid-Liquid Sweetening Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-3. Table-3 Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min Volume of 7 % aqueous solution of sodium hydroxide containing catalyst taken, ml Air flow rate at NTP, litres/min 1530 100 300 10 20 0.95-1.05 (Table Removed) Example 5 Liquid-Liquid Sweetening Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-4. Table-4 Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min Volume of 7 % aqueous solution of sodium hydroxide containing catalyst taken, ml Air flow rate at NTP, litres/min 1954 100 300 10 20 0.95-1.05 (Table Removed) Example 6 Liquid-Liquid Sweetening Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-5. Table-5 Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min Volume of 7 % aqueous solution of sodium hydroxide containing catalyst taken, ml Air flow rate at NTP, litres/min 2470 100 300 10 20 0.95-1.05 (Table Removed) Example 7 Liquid-Liquid Sweetening Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-6. Table-6 Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min Volume of 7 % aqueous solution of sodium hydroxide containing catalyst taken, ml Air flow rate at NTP, litres/min 2280 100 300 10 50 0.95-1.05 (Table Removed) Advantages of the Invention The main advantages of the present invention over the previous inventions are : (a) The present invention provides a process for liquid-liquid sweetening of lighter petroleum distillates like pentanes, light straight run naphtha (LSRN), FCC cracked naphtha, and gasoline using metal phthalocyanine sulphonamide catalyst. (b) Metal phthalocyanine sulphonamide catalyst used in the present invention are found to be highly active for liquid-liquid sweetening of lighter petroleum distillates. (c) Metal phthalocyanine sulphonamide catalyst used in the present invention are not dusty and do not create handling problems as encountered with the conventional cobalt phthalocyanine disulphonate catalyst. Therefore, admixing with water to make slurry is not required. (d) As the metal phthalocyanine sulphonamide used as catalyst in this invention are insoluble in acidic medium their isolation is easier than conventional cobalt phthalocyanine sulphonate catalyst. We Claim: 1. A process for the liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst which comprises mixing the sour petroleum distillates selected from pentanes, light straight run naphtha (LSRN), Fluid catalytic cracked naphtha and gasoline with an aqueous solution of alkali metal hydroxide such as herein described in the concentration ranging from 1 wt% to 50 wt% containing metal phthalocyanine sulphonamide catalyst in the concentration ranging from 5 to 4000 ppmw in the presence of air, oxygen or any other oxygen containing gas at a temperature ranging between 25°C to 90°C and pressure ranging between 1 kg/cm2 to 60 kg/cm2, thereby converting the mercaptans present in the lighter petroleum distillates to corresponding hydrocarbon soluble disulphides, separating the sweetened petroleum distillates from alkali solution containing catalyst by known methods and recalculating the alkali solution containing catalyst for further sweetening process. 2. A process as claimed in claim 1, wherein the metal phthalocyanine sulphonamide used is selected from the group consisting of cobalt, manganese, nickel, iron, vanadium phthalocyanine sulphonamide and their N-substituted sulphonamide derivatives most preferably cobalt phthalocyanine sulphonamide. 3. A process as claimed in claims 1-2, wherein the aqueous solution of alkali metal hydroxides used is selected from group consisting of aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide and cesium hydroxide most preferably aqueous solution of sodium and potassium hydroxide. 4. A process as claimed in claims 1-3, wherein the concentration of aqueous solution of alkali metal hydroxide used is preferably in the range 4% to 25% by weight. 5. A process as claimed in claims 1-4, wherein the metal phthalocyanine sulphonamide catalyst used is preferably in the concentration ranging between 10- 1000 ppmw. 6. A process as claimed in claims 1-5, wherein the liquid-liquid sweetening is preferably effected by air. 7. A process as claimed in claims 1-6, wherein the liquid-liquid sweetening is preferably effected at a temperature ranging between 20°C to 60°C. 8. A process as claimed in claims 1-7, wherein the liquid-liquid sweetening is effected preferably at 1 kg/cm2 to 20 kg/cm2. 9. A process as claimed in claims 1-8, wherein the liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst is used for treating petroleum fractions with mercaptan sulphur content in the range 10 ppmw to 20,000 ppmw. 1 0. A process as claimed in claims 1 -9, wherein liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst is effected in batch or continuous manner. 1 1 . A process for the liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst substantially as herein described with reference to the examples.

Full Text

The present invention relates to a process for liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst.
Particularly, the invention relates to a procef; for liquid-liquid sweetening of lighter petroleum distillates like pentanes, lighter straight run naphtha (LSRN), FCC cracked naphtha and gasoline, comprising of mixing sour light petroleum distillates , alkali solution containing metal phthalocyanine sulphonamide catalyst in presence of air, whereby the mercaptans present in the light petroleum distillates are oxidized to disulphides, which being hydrocarbon soluble goes with the sweetened petroleum distillates, and the alkali solution containing catalyst is recirculated.
Metal phthalocyanine sulphonamide catalyst has been prepared by a procedure as described and disclosed in our copending Indian patent application No 1032/DEL/2000.
It is known that the presence of mercaptans in the petroleum products like LPG, naphtha, gasoline, keiosene, ATF etc is highly undesirable due to their foul odour and highly corrosive nature. These are also poisonous to the catalysts and adversely affect the performance of tetraethyl lead as octane booster. Although there are several processes known for the removal of mercaptans from petroleum products, the most common practice is to oxidize the mercaptans present, to less deleterious disulphides with air in the presence of a catalyst. Generally, the lower mercaptans present in LPG, pentanes, LSRN and light thermally cracked naphtha are first extracted in alkali solution and then oxidized to disulphides with air in the presence of a catalyst. The disulphides, being insoluble in alkali solution is separated out from the top and the alkali is regenerated. In the liquid-liquid sweetening the lower mercaptans present in petroleum products like pentanes, LSRN, FCC cracked naphtha etc are converted to disulphides by direct oxidation with air in the presence of alkali solution and catalyst. The higher molecular weight mercaptans present in petroleum products like heavy naphtha, FCC gasoline, ATF and kerosene are oxidized to disulphides with air in a fixed bed reactor containing catalyst impregnated on a suitable support like activated carbon (Catal. Rev. Sci. Eng. 35(4), 571-609, 1993).

It is also well known that the phthalocyanines of the metals like cobalt, iron, manganese, molybdenum and vanadium catalyze the oxidation of mercaptans to disulphides in alkaline medium. Among these cobalt and vanadium phthalocyanines are preferred. As the metal phthalocyanines are not soluble in aqueous medium, for improved catalytic activity their derivatives like sulphonated and carboxylated metal phthalocyanines are used as catalyst for sweetening of petroleum fractions. For example use of cobalt phthalocyanine monosulphonate as the catalyst in the fixed bed sweetening of various petroleum products (US Patents No. 3,371,031; 4,009,120; 4,207,173; 4,028,269; 4,087,378; 4,141,819; 4,121,998; 4,124,494; 4,124,531) and cobalt phthalocyanine disulphoante (US Patent No. 4, 250, 022), tetra sulphonate (US Patent No. 2,622,763) and the mixture thereof (US Patent No. 4,248,694) as catalysts for liquid-liquid sweetening and alkali regeneration in mercaptan extraction of light petroleum distillates has been reported. The use of phenoxy substituted cobalt phthalocyanine as sweetening catalyst (Ger Offen 3,816, 952), cobalt and vanadium chelates of 2, 9, 16, 23-tetrakis (3,4-dicarboxybenzoyl) phthalocyanine as effective catalyst for both homogeneous and fixed bed mercaptan oxidation (Ger Offen 2, 757, 476; Fr. Demande 2,375,201) and cobalt, vanadium chelates of tetrapyridinoporphyrazine as active catalysts for sweetening of sour petroleum distillates (Ger Offen 2,441, 648) has also been reported.
It is well known that the catalysts used for the liquid-liquid sweetening of lighter petroleum distillates like pentanes, light straight run naphtha (LSRN), FCC cracked naphtha and gasoline are di-, tri-and tetra sulphonates of metal phthalocyanines particularly those of cobalt and vanadium phthalocyanines; cobalt phthalocyanine sulphonates being specially preferred. The cobalt phthalocyanine sulphonates, differ in activity and in their solubility characteristics depending upon the number of sulphonate functionalities leading to problems in their use as catalysts.
Cobalt phthalocyanine disulphonate a commonly used catalyst in sweetening of light petroleum distillates is extremely dusty in the dry fine powder form and causes handling problem. To overcome this problem cobalt phthalocyanine disulphonate is admixed with

Water and commonly used as a slurry. However, with insufficient mixing the cobalt phthalocyanine disulphonate precipitates out from the slurry. Moreover, even if the slurry is mixed sufficiently, it retains the cobalt phthalocyanine disulphonate in suspension for a particular length of time only, beyond which the slurry becomes extremely viscous and may form gel, making it very difficult to remove the material from packaging. Cobalt phthalocyanine tetrasulphonate, on the other hand, is highly soluble in water and its use can eliminate precipitation and gel forming problems associated with the use of cobalt phthalocyanine disulphonate. However, it is reported that cobalt pthalocyanine tetrasulphonate has lower catalytic activity than cobalt phthalocyanine disulphonate (US patent 4, 885,268).
In one of our application 1032/del/2000 we reported an improved process for the preparation of metal phthalocyanine sulphonamide catalyst useful for sweetening and obviates the drawback as detailed above.
The main objective of the present invention is to provide a process for liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst, which obviates the drawbacks as details above.
Accordingly the present invention provides a process for the liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst which comprises mixing the sour petroleum distillates selected from pentanes, light straight run naphtha (LSRN), Fluid catalytic cracked naphtha and gasoline with an aqueous solution of alkali metal hydroxide such as herein described in the concentration ranging from 1 wt% to 50 wt% containing metal phthalocyanine sulphonamide catalyst in the concentration ranging from 5 to 4000 ppmw in the presence of air, oxygen or any other oxygen containing gas at a temperature ranging between 25°C to 90°C and pressure ranging between 1 kg/cm2 to 60 kg/cm2, thereby converting the mercaptans present in the lighter petroleum distillates to corresponding hydrocarbon soluble disulphides, separating the sweetened petroleum distillates from alkali solution containing catalyst by known methods and recalculating the alkali solution containing catalyst for further sweetening process.

In an embodiment of the present invention the metal phthalocyanine sulphonamide used is selected from the group consisting of cobalt, manganese, nickel, iron, vanadium phthalocyanine sulphonamide and their N-substiruted sulphonamide derivatives most preferably cobalt phthalocyanine sulphonamide.
In an embodiment of the present invention the aqueous solution of alkali metal hydroxides used is selected from group consisting of aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide most preferably aqueous solution of sodium and potassium hydroxide.
In another embodiment of the present invention the concentration of aqueous solution of alkali metal hydroxide used is preferably in the range 4 % to 25 % by weight.
In yet another embodiment of the present invention the metal phthalocyanine sulphonamide catalyst used is preferably in the concentration range between 10-1000 ppniw.
In still another embodiment of the present invention the liquid-liquid sweetening is preferably effected in the presence of air.
In still another embodiment of the present invention the liquid-liquid sweetening is preferably effected at a temperature ranging between 20°C to 60°C.
In still another embodiment of the present invention the liquid-liquid sweetening is effected preferably at 1 kg/cm2 to 20 kg/cm2.
In an embodiment of the present invention the liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst is used for treating petroleum fractions with mercaptan sulphur content in the range 10 ppmw to 20,000 ppmw.

In yet another embodiment of the present invention liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst can be effected in batch or continuous manner.
Process Description
In the liquid-liquid sweetening process herein contemplated, the mercaptan containing (sour) lighter petroleum distillates like pentanes, light straight run naphtha (LSRN), FCC cracked naphtha and gasoline are mixed in continuous or batch manner with aqueous solution of alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, containing cobalt phthalocyanine sulphonamide catalyst, and air or any other oxygen containing gas. The mercaptans present in the light petroleum distillates are oxidized to corresponding disulphides by oxygen present in air in presence of catalyst and alkali. The disulphides thus formed being hydrocarbon soluble goes with the sweetened petroleum distillates and the alkali solution containing catalyst is recirculated after gravity separation.
The sweetening process is effected with the metal phthalocyanine sulphonamide catalyst like cobalt, manganese, nickel, iron and vanadium phthalocyanine sulphonamide and their N-substituted derivatives, the preferred catalyst is cobalt phthalocyanine sulphonamide. The catalyst is used in the concentration 5 to 4000 ppmw related to alkali solution, the preferred range is 10 - 1000 ppmw.
The aqueous solution of alkali metal hydroxide used in this sweetening process is aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide preferably aqueous solution of sodium and potassium hydroxide. The concentration of aqueous solution of alkali metal hydroxide used is 1 % to 50 % the preferably 4 % to 25 %.
This liquid-liquid sweetening process is effected at pressure ranging from atmospheric to 60 kg/cm2 preferred range being 1 to 20 kg/cm2. Similarly the process is effected at the temperature ambient to 90°C, preferably 20°C to 60°C.

The process is effected by air, oxygen or any other oxygen containing gas, air being especially preferred.
The following examples are given by way of illustration and therefore, should not be construed to line to the scope of the invention.
Example 1
Preparation of Cobalt Phthalocyanine Sulphonamide Catalyst as described in our Indian Patent Application No. 1032/Del/2000
Preparation of Cobalt Phthalocyanine Sulphonyl Chloride
For the preparation of cobalt phthalocyanine sulphonyl chloride, 30 parts by weight of cobalt phthalocyanine were slowly added with stirring to 315 parts by weight of chlorosulphonic acid. The reaction mixture was heated to about 75°C in one hour and from 75°C to about 130°C in 1.5 hours by controlling the heating rate, with constant stirring. The reaction mixture, after maintaining 130-135°C for additional 4 hours, was cooled to 60-65°C, and then 123 parts of thionyl chloride were slowly added. The whole contents were heated to 79°C and maintained at this temperature for one hour. The reaction product was cooled to room temperature and slowly added to crushed ice, keeping the temperature preferably below 5°C. The precipitated cobalt phthalocyanine sulphonyl chloride was filtered and washed thoroughly with cold water. The filtered cake was stored wet at 0°C till further processing.
Preparation of Cobalt Phthalocyanine Sulphonamide
In a typical preparation of cobalt phthalocyanine sulphonamides, total wet cake of cobalt phthalocyanine sulphonyl chloride, obtained was dispersed in 900 parts of ice water and 190 parts of methanol added to get homogeneous dispersion. The reaction mixture was stirred at 5-8°C and ammonia gas was passed till the mixture was fairly alkaline (pH 8-9). Pyridine (1.2 parts) was then added and the mixture stirred at room temperature for 20 minutes. This was followed by addition of 6 parts of 10% sodium hydroxide solution followed by stirring the reaction mixture for 40 minutes at room temperature. The contents were then heated to 80°C and after maintaining at this temperature for 1 hour, cooled to room temperature and poured over a mixture of ice and concentrated hydrochloric acid keeping the pH fairly acidic (2-3). The precipitated cobalt phthalocyanine tetrasulphonamide was filtered, washed thoroughly with cold water and dried in vacuum oven to yield 44 gms of the product. The FAB mass spectral analysis of the sulphonamide obtained using cobalt phthalocyanine as the starting material showed the presence of tetra sulphonamide as the major isomer, followed by trisulphonamide and disulphonamide isomers.
Example 2 Liquid-Liquid Sweetening
The experimental set-up used consisted of a 250 ml round bottom flask, fitted with a mechanical stirrer with teflon blade, a gas inlet tube and a condenser. The feed was prepared by adding standard 1-hexanethiol to light naphtha (b.p. 60-90°C) and its mercaptan sulphur content was estimated by UOP method 163-89. The catalyst solution was prepared by adding calculated amount of cobalt phthalocyanine sulphonamide to 7 % aqueous solution of sodium hydroxide. The prepared feed (100 ml) was taken in the RB flask and 7 % aqueous solution of sodium hydroxide containing catalyst was added to it. The stirrer (speed 1600 rpm) and air flow(rate about 1.0 lit/min) were then started. The reaction was carried out at room temperature (25-35°C) for 10 min. The reaction mass was then transferred to a separating funnel and the treated naphtha was separated. The aqueous sodium hydroxide solution layer containing the catalyst was reused with fresh
naphtha (100 ml) doped with 1-hexanethiol. The catalyst solution was thus repeatedly used number of times. The mercaptan sulphur content of the treated naphtha obtained after each experiment was estimated by UOP method 163-89. Results are given in Table-1.
Table-1

Mercaptan sulphur in feed, 'S' ppmw
Volume of feed taken, ml
Catalyst concentration in alkali, ppmw
Reaction time, min
Volume of 7 % aqueous solution of
sodium hydroxide containing catalyst taken, ml
Air flow rate at NTP, litres/min480
100
300
10
20
0.95-1.05

(Table Removed)
Example 3
Liquid-Liquid Sweetening
Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-2.
Table-2
Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min
Volume of 7 % aqueous solution of
sodium hydroxide containing catalyst taken, ml
Air flow rate at NTP, litres/min
1100
100
300
10
20
0.95-1.05
(Table Removed)
Example 4
Liquid-Liquid Sweetening
Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-3.

Table-3
Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min
Volume of 7 % aqueous solution of
sodium hydroxide containing catalyst taken, ml
Air flow rate at NTP, litres/min
1530
100
300
10
20
0.95-1.05
(Table Removed)
Example 5
Liquid-Liquid Sweetening
Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-4.

Table-4
Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min
Volume of 7 % aqueous solution of
sodium hydroxide containing catalyst taken, ml
Air flow rate at NTP, litres/min

1954
100
300
10
20
0.95-1.05

(Table Removed)
Example 6
Liquid-Liquid Sweetening
Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-5.

Table-5
Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min
Volume of 7 % aqueous solution of
sodium hydroxide containing catalyst taken, ml
Air flow rate at NTP, litres/min
2470
100
300
10
20
0.95-1.05

(Table Removed)
Example 7
Liquid-Liquid Sweetening
Procedure followed and experimental details were same as given in Example 2. The results obtained are presented in Table-6.

Table-6
Mercaptan sulphur in feed, 'S' ppmw Volume of feed taken, ml Catalyst concentration in alkali, ppmw Reaction time, min
Volume of 7 % aqueous solution of
sodium hydroxide containing catalyst taken, ml
Air flow rate at NTP, litres/min

2280
100
300
10
50
0.95-1.05

(Table Removed)
Advantages of the Invention
The main advantages of the present invention over the previous inventions are :
(a) The present invention provides a process for liquid-liquid sweetening of lighter
petroleum distillates like pentanes, light straight run naphtha (LSRN), FCC
cracked naphtha, and gasoline using metal phthalocyanine sulphonamide catalyst.
(b) Metal phthalocyanine sulphonamide catalyst used in the present invention are
found to be highly active for liquid-liquid sweetening of lighter petroleum
distillates.
(c) Metal phthalocyanine sulphonamide catalyst used in the present invention are not
dusty and do not create handling problems as encountered with the conventional
cobalt phthalocyanine disulphonate catalyst. Therefore, admixing with water to
make slurry is not required.
(d) As the metal phthalocyanine sulphonamide used as catalyst in this invention are
insoluble in acidic medium their isolation is easier than conventional cobalt
phthalocyanine sulphonate catalyst.

We Claim:
1. A process for the liquid-liquid sweetening of lighter petroleum distillates using
metal phthalocyanine sulphonamide catalyst which comprises mixing the sour
petroleum distillates selected from pentanes, light straight run naphtha (LSRN),
Fluid catalytic cracked naphtha and gasoline with an aqueous solution of alkali
metal hydroxide such as herein described in the concentration ranging from 1
wt% to 50 wt% containing metal phthalocyanine sulphonamide catalyst in the
concentration ranging from 5 to 4000 ppmw in the presence of air, oxygen or any
other oxygen containing gas at a temperature ranging between 25°C to 90°C and
pressure ranging between 1 kg/cm2 to 60 kg/cm2, thereby converting the
mercaptans present in the lighter petroleum distillates to corresponding
hydrocarbon soluble disulphides, separating the sweetened petroleum distillates
from alkali solution containing catalyst by known methods and recalculating the
alkali solution containing catalyst for further sweetening process.
2. A process as claimed in claim 1, wherein the metal phthalocyanine sulphonamide
used is selected from the group consisting of cobalt, manganese, nickel, iron,
vanadium phthalocyanine sulphonamide and their N-substituted sulphonamide
derivatives most preferably cobalt phthalocyanine sulphonamide.
3. A process as claimed in claims 1-2, wherein the aqueous solution of alkali metal
hydroxides used is selected from group consisting of aqueous solution of sodium
hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide and
cesium hydroxide most preferably aqueous solution of sodium and potassium
hydroxide.
4. A process as claimed in claims 1-3, wherein the concentration of aqueous solution
of alkali metal hydroxide used is preferably in the range 4% to 25% by weight.
5. A process as claimed in claims 1-4, wherein the metal phthalocyanine
sulphonamide catalyst used is preferably in the concentration ranging between 10-
1000 ppmw.
6. A process as claimed in claims 1-5, wherein the liquid-liquid sweetening is
preferably effected by air.

7. A process as claimed in claims 1-6, wherein the liquid-liquid sweetening is
preferably effected at a temperature ranging between 20°C to 60°C.
8. A process as claimed in claims 1-7, wherein the liquid-liquid sweetening is
effected preferably at 1 kg/cm2 to 20 kg/cm2.
9. A process as claimed in claims 1-8, wherein the liquid-liquid sweetening using
metal phthalocyanine sulphonamide catalyst is used for treating petroleum
fractions with mercaptan sulphur content in the range 10 ppmw to 20,000 ppmw.
1 0. A process as claimed in claims 1 -9, wherein liquid-liquid sweetening using metal phthalocyanine sulphonamide catalyst is effected in batch or continuous manner.
1 1 . A process for the liquid-liquid sweetening of lighter petroleum distillates using metal phthalocyanine sulphonamide catalyst substantially as herein described with reference to the examples.

Documents:

726-del-2001-abstract.pdf

726-del-2001-claims.pdf

726-del-2001-correspondence-others.pdf

726-del-2001-correspondence-po.pdf

726-del-2001-description (complete).pdf

726-del-2001-form-1.pdf

726-del-2001-form-18.pdf

726-del-2001-form-2.pdf

726-del-2001-form-3.pdf

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Patent Number

230888

Indian Patent Application Number

726/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

29-Jun-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	TURUGA SUNDARA RAMA PRASADA RAO	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
2	GUR PRATAP RAI	BHARAT PETROLEUM CORPORATION LIMITED, MAHUL, MUMBAI-400 074, INDIA.
3	BIR SAIN	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
4	SOM NATH PURI	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
5	GAUTAM DAS	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
6	BHAGWATI PRASAD BALODI	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
7	SUNIL KUMAR	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
8	ANIL KUMAR	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
9	VIRENDRA KUMAR KAPOOR	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
10	VIRENDRA KUMAR BHATIA	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.

PCT International Classification Number

C10G 19/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA