US 3164544 A
Description (OCR text may contain errors)
United States Patent OXEDATKVE SWEETENING WHTH BASE AND QUATERNARY AMMGNIUM QQMPOUND Rolland G. Bowers, Perryshurg, Ghio, assignor to Sun Oil Company, Philadelphia, El a, a corporation of New Jersey No Drawing. Continuation of applications Ser. No. 137,717, Sept. 13, 1961, and Ser. No. 170,510, Feb. 1, 1962. This application Feb. 26, P263, Ser. No. 261,16
13 Claims. (Cl. 2082ti6) This invention relates to sweetening sour hydrocarbon distillates, and more particularly to a manner of providing increased sweetening rate.
It is known in the art to sweeten sour hydrocarbon distillates by contact with phenylene diamine compounds in the presenceof an alkaline catalyst. Such process is commonly referred to as inhibitor sweetening. The process is believed to involve oxidation of mercaptans to disulfides, by gaseous oxygen, catalyzed by the phenylene diamine compound and the alkaline material.
In the known process, the rate of mercaptan conversion is sometimes not rapid enough for satisfactory results. According to the present invention, a novel man ner is provided of obtaining more rapid sweetening. This result is obtained by carrying out the process in the presence of a quaternary ammonium nitrite or halide.
The quaternary ammonium nitrite or halide which is used in the process contains at least one aliphatic or cycloaliph-atic radical having at least 12 carbon atoms. Such radicals can advantageously be those which are contained in naturally occurring fatty acids such as coconut oil fatty acids. It is known in the art to convert coconut oil fatty acids to mixtures of amines, in which one or more of the alkyl radicals originally attached to the carboxyl group of the fatty acid, is contained in the amine. It is also known to convert such amines to quaternary ammonium nitrites or halides containing four alkyl groups, at least one of which is the alkyl radical derived from the coconut oil fatty acids. Thus, for example, dicoco dimethyl ammonium nitrite or halide contains two such alkyl groups and two methyl groups attached to the nitrogen atom. The aliphatic or cycloaliphatic group or groups containing 12 or more carbon atoms can also be derived from other naturally occurring fatty acid mixtures, or from individual fatty acids, or from naturally occurring cycloaliphatic acids such as petroleum naphthenic acids or rosin. Usually the hydrocarbon radical will not contain more than 24 carbon atoms, though greater numbers are suitable in some cases.
Examples of suitable quaternary ammonium nitrites and halides for use according to the invention include monococo trimethyl ammonium nitrite, dodecyl trimethyl ammonium nitrite, hexadecyl triethyl ammonium nitrite, dihexadecyl dimethyl ammonium nitrite, cetyl lauryl dimethyl ammonium nitrite, dioleyl diethyl ammonium nitrite, din-aphthenyl dimethyl ammonium nitrite, diabietyl dimethyl ammonium nitrite, and the corresponding halides, etc. Preferred nitrites are those containing one or two, and more preferably one, alkyl radicals, each having 12 to 14 carbon atoms, and two or three radicals each having 1 to 3 carbon atoms. Particularly preferred compounds are those containing alkyl radicals derived from coconut oil acids.
The amount of nitrite or halide in the sweetening mixture is preferably in the range from 0.001 to 1.0 weight percent based on hydrocarbon charge stock. Other amounts can be used in some cases; greater amounts are usually avoidedsince unnecessary for satisfactory results.
EJ54544 i atentecl Jan. 5, 1965 "ice The known phenylene diamine compounds for use in inhibitor sweetening are generally suitable for use according to the invention. The most commonly used com pound is N,N-di-secondary-butyl-p-phenylene diamine. Other suitable phenylene diamine compounds include N,N'-di-isopropyl-p-phenylene diamine, N,N-di-secondary-amyl-p-phenylene diamine, N-isopropyl-N'-secondarybutyl-p-phenylene diamine, N-isopropyl-N-secondaryamyl-p-phenylene diamine, N-secondary-butyl-N'-secondary-amyl-p-phenylene diamine, etc. The amount of phenylene diamine compound employed is generally within the approximate range from 0.0001 to 1.0 weight percent based on hydrocarbons, more preferably, 0.001 to 0.1 weight percent. However, any amount known to be suitable for inhibitor sweetening can be used.
The alkaline material which is employed in the process according to the invention is any alkaline material which is known for use in catalyzing inhibitor sweetening reactions. Examples of suitable alkaline materials are the hydroxides of the alkali metals or alkaline earth metals, sodium, potassium, calcium, strontium, barium, etc., ammonia, and organic basic compounds which are substantially insoluble in hydrocarbons, e.g., polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, 1,2-diaminopropane, 1,3-diaminobutane, 1,3,5- triaminopentane, 1,3,6-triaminohexane, 1,3,5,7-tetraminoheptane, etc., aminoalcohols including aminoethanol, diaminopropanol, triaminobutanol, tetraminopentanol, etc. and quaternary ammonium compounds including tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetramethyl ammonium methoxide, tetramethyl ammonium ethoxide, tetraethyl ammonium ethoxide, etc. Mixtures of alkaline materials, e.g. of ammonia and sodium hydroxide, etc., can be employed.
The amount of alkaline material which is employed in the process of the invention is preferably within the approximate range from 0.01 to 5 weight percent, although any amount known to be suitable for use in oxidative sweetening operations can be employed.
The temperature conditions of the sweetening operation according to the invention can be those which are employed in the conventional sweetening operations, eg in the range from 50 F. to F., though other temperatures can be employed.
Agitation of the sweetening mixture promotes the conversion of mercaptans. Agitation can be provided only at the beginning of the sweetening operation, or irregularly during the operation, or it can be provided periodically or continuously during the operation. In some cases at least, the presence of the nitrite or halide according to the invention reduces the extent of the agitation needed to provide satisfactory sweetening rate.
Molecular oxygen is required for the sweetening operation. Frequently, petroleum distillates normally contain sufiicient dissolved oxygen to obtain substantial sweetening. Additional oxygen can be supplied, regularly or irregularly, if needed.
The process according to the invention is applicable generally to those mercaptan-containing petroleum frac tions, such as gasoline, naphtha, kerosine and fuel oil fractions, which are known to be susceptible to oxidative sweetening with alkaline catalyst; A typical charge stock is a 62 API, 400 F. endpoint, catalytically cracked and caustic-pretreated gasoline containing about 0.01 weight percent mercaptan sulfur, but the applicability of the invention to other known charge stocks for oxidative sweetening processes will be readily apparent.
The following reaction mixture is prepared:
Cc. Petroleum fuel containing 0.0069 Wt. percent mercaptans n 400 20 B. caustic soda 10 N,N'-dibutyl phenylene diamine.
Monococo trimethyl ammonium nitrite.
The amounts of the latter two components are equivalent to 5 pounds of the diamine per 1000 barrels of fuel, and pounds per 1000 barrels of fuel of a mixture of the nitrite and isopropanol, containing 50% of the nitrite.
The mixture is agitated for one hour at room temperature, then allowed to stand for 5 hours. 100 cc. of air are then injected, and the mixture shaken for minutes. The mixture is then allowed to stand. The following table shows the mercaptan contents at the indicated times, measured from the initial mixing. For comparison, results are shown for identical operation, with the monococo trimethyl ammonium nitrite omitted.
Wt. percent Mereaptan- Monococo trimethyl am- Hours monium nitrite Present Absent These data show the acceleration in rate of mercaptan conversion obtained by the use of the monococo trimethyl ammonium nitrite.
' Example 2 The latter two components are added as a mixture with aqueous isopropanol, the solution containing of the soya chloride and 25% of the dicoco chloride. The mixture is used in amount equivalent to one pound of mixture per 1000 barrels of gasoline.
The soya trimethyl ammonium chloride is a compound similar to the monococo trimethyl ammonium chloride disclosed previously, but containing the hydrocarbon radical of soybean fatty acids in place of the hydrocarbon radicalor coconut oil fatty acids.
The reaction mixture is blown with air for seconds, then shaken for 30 minutes and allowed to stand. The reaction mixture is cloudy immediately after shaking, but clear after 2 hours. The following table shows the mercaptan contents at the indicated times, measured from the initial mixing. For comparison, results are shown for identical operation, with the mixture of soya trimethyl ammonium chloride and dicoco dimethyl ammonium chloride omitted.
The copper dish gum of the gasoline after 24 hours is 11 mg./100 ml. in the case Where the quaternary chlorides are present, and 19 mg./100 ml. in the case where they are absent.
4 Example 3 The procedure of Example 2 is repeated, using however a mixture, with aqueous isopropanol, of dicoco dimethyl ammonium chloride (constituting 75% of the mixture) as sole quaternary chloride, in place of the mixture containing two quaternary chlorides as used in Example 2. The following results are obtained:
Wt. percent Mercaptan Hours Quaternary Quaternary chlorides chlorides present absent Copper dish gum after 24 hours is 14 mg./ ml. where quaternary chloride is present, 19 mg./100 ml. where absent.
Example 4 The procedure of Example 2 is repeated, using however a different gasoline, containing initially 0.0029 wt. percent mercaptan, and using N,N'-dibutyl phenylene diamine, in amount equivalent to 5 pounds thereof per 1000 barrels of gasoline in addition to the other components of the reaction mixture; the quaternary chloride mixture with aqueous isopropanol is used in amount equivalent to 5 pounds per 1000 barrels of gasoline, rather than 1 pound per 1000 barrels as in Example 2; Comparison is made with another reaction mixture containing the above phenylene diamine derivative but lacking the two quaternary chlorides. The following results are obtained:
Wt. percent Mereaptan Hours Quaternary Quaternary chlorides chlorides present absent 0. 0006 0. 0011 0. 0001 0. 0007 nil 0. 0005 Copper dish gum after 24 hours is 7 mg./100 ml. where quaternary chlorides are present, 13 where absent.
Example 5 Example 4 is repeated substituting the dicoco derivative of Example 3 for the two quaternary chlorides used in Examples 2 and 4. The'following results are obtained:
Copper dish gum after 24 hours is 9 mg./ 100 ml. where quaternary chlorides are present, 13 mg./100 ml. where absent.
Generally similar results to those obtained in the preceding examples are obtained using other quaternary ammonium nitrites or halides, phenylene diamine agents and alkaline materials such as those specifically disclosed previously. Halides contemplated for use include bromides and iodides as well as chlorides, though the latter are preferred.
This application is a continuation of application Serial No. 137,717, filed September 13, 1961, now abandoned, which was a continuation-in-part of application Serial No. 861,464, filed December 23, 1959, now abandoned. This application is also a continuation of application Serial No. 170,510, filed February 1, 1962, now abandoned.
The invention claimed is:
1. Process for reducing mercaptan content of hydrocarbons which comprises contacting hydrocarbons containing mercaptans with an alkaline catalyst and a quaternary ammonium nitrite containing at least one hydrocarbon radical selected from the group consisting of aliphatic and cycloaliphatic radicals and having at least 12 carbon atoms, in the presence of oxygen and a phenylene diamine sweetening agent.
2. Process according to claim 1 wherein said nitrite contains three alkyl groups each having 12 to 14 carbon atoms and one alkyl group having 1 to 3 carbon atoms.
3. Process according to' claim 1' wherein said nitrite is monococo trimethyl ammonium nitrite.
4. Process according to claim 1 wherein the amount of alkaline catalyst is in the range from 0.01 to 5 weight percent based on hydrocarbons.
5. Process according to claim 1 wherein the amount of said nitrite is in the range from 0.001 to 1.0 weight percent based on hydrocarbons.
6. Process according to claim 1 wherein the amount of said agent is in the range from 0.0001 to 1.0 weight percent based on hydrocarbons.
7. Process for reducing mercaptan content of hydrocarbons which comprises contacting hydrocarbons containing mercaptans with an alkaline catalyst and a quaternary ammonium halide containing at least one hydrocarbon radical selected from the group consisting of aliphatic and cyclojaliphatic radicals and having at least 12 carbon atoms, in the presence of oxygen. 1
8. Process according to claim 7 wherein said halide contains 2 to 3 alkyl groups each having 12 to 14 carbon atoms and 1 to 2 alkyl groups having 1 to 3 carbon atoms.
9. Process according to claim 7 wherein said halide is dicoco dimethyl ammonium chloride.
10. Process according to claim 7 wherein the amount of alkaline catalyst is in the range from 0.01 to 5 weight percent based on hydrocarbons.
11. Process according to claim 7 wherein the amount of said halide is in the range from 0.001 to 1.0 weight percent based on hydrocarbons.
12. Process according to claim 7 wherein the contacting is in the presence of a phenylene diamine sweetening agent in amount in the range from 0.0001 to 1.0 weight percent based on hydrocarbons.
13. Process for reducing mercaptan content of hydrocarbons which comprises contacting hydrocarbons containing mercaptans with an alkaline catalyst and a quaternary ammonium compound containing at least one hydrocarbon radical selected from the group consisting of aliphatic and; cycloaliphatic radicals and having at least 12 carbon atoms, in the presence of oxygen, said compound being selected from the group consisting of quaternary ammonium nitrites and quaternary ammonium halides.
References Cited in the file of this patent UNITED STATES PATENTS