US2702237A

US2702237A - Inhibited chlorine-containing petroleum oils and method of preparing same

Info

Publication number: US2702237A
Application number: US162607A
Authority: US
Inventors: Leonard V Sorg
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1950-05-17
Filing date: 1950-05-17
Publication date: 1955-02-15
Anticipated expiration: 1972-02-15

Description

United INHIBITED CHLORlNE-CONTAINING PETRO- LEUM OILS AND METHOD OF PREPARING SAME No Drawing. Application May 17, 1950, Serial No. 162,607

13 Claims. (Cl. 44-63) This invention pertains to inhibited sweetened lowerboiling hydrocarbon oil distillates, and more particularly to inhibited chlorine-containing sweetened lower-boiling petroleum distillates which meet copper strip specifications, and to the method of obtaining the same.

Hydrocarbon oils, particularly the lower-boiling petroleum distillates, such as for example, naphthas, kerosenes, fuel oils, etc., either straight-run or cracked, 'are treated to convert obnoxious sulfur compounds, such as mercaptans, into less obnoxious and less odoriferous sulfur compounds. art and is generally referred to as sweetening and the products so treated are called sweetened products.

Among the various methods of sweetening is the hypochlorite'method in which the sour distillate lS treated with an aqueous hypochlorite solution or with an aqueous solution of an alkali metal or alkaline earth hypochlorite, such as for example, sodium hypochlorite, lithium hypochlorite, potassium hypochlorite, calcium hypochlorite, barium hypochlorite, etc. Heavy metal hypochlorites, such as zinc, have also been used for this purpose.

It is well known that the lower-boiling petroleum dlS- tillates of the above type are frequently subjected to various tests to determine whether they pass certain specifications. One of the tests usually required is a so-called copper strip or copper corrosion test, in which a highly polished copper strip is immersed in the oil under specified conditions to determine whether the oil will cause a discoloration of the copper strip, and if so, the intensity of such discoloration. It is known that sulfur and certain classes of organic sulfur compounds will cause copper strip staining. It also has been observed that the presence of chlorine and/or compounds containing unstable chlorine will also cause copper strip staining. It has been noted that petroleum oils having a chlorine content of at least about ten parts per million p. p. in.) will not pass the copper strip staining test. It is, therefore, highly desirable that the lower-boiling petroleum distillates, sweetened with a hypochlorite solution or with other chlorine-containing compounds be treated to overcome this tendency toward copper strip staining.

It is an object of the present invention to provide a hydrocarbon oil sweetened with a chlorine-containing compound which will pass the copper strip tests. Another object of the invention is to provide a hypochlorite sweetened petroleum distillate which is non-corrosive to copper. A further object of the invention is to provide a copper non-staining hypochlorite sweetened low-boiling petroleum distillate normally containing a sufficient amount of chlorine to cause copper staining.

Another object of the invention is to provide a copper non-staining hypochlorite sweetened low-boiling petroleum distillate containing more than 10 parts per million chlorine and which normally causes excessive copper staining. Still another object of the invention is to provide a method of treating hypochlorite sweetened petroleum distillates containing more than ten parts per million chlorine to reduce the tendency of such distillates to excessively stain copper. Other objects and advan tages of the invention will become apparent from the following description thereof.

In accordance with the present invention hypochlorite sweetened normally liquid petroleum distillates, straightrun or cracked, normally containing more than ten parts per million chlorine and which normally fail to pass the copper strip test are treated with from about 0.000l% to about 0.5%, and preferably from about 0.0005% to Such treatment is well known in the atent about 0.01% of a morpholine. The term morpholine compound, as used herein and in the appended claims, includes morpholine (NH[C2H4]2O) per se, and derivatives thereof, such as for example, methyl morpholine, phenyl morpholine, morpholine ethanol, morpholine ethyl ether, morpholine vinyl ether, etc.

The method of sweetening sour petroleum distillates with hypochlorite solutions is well known. Briefly, the process comprises treating a light petroleum distillate with an aqueous alkali or alkaline earth hypochlorite solution under controlled conditions, followed by a caustic wash to remove any acidic bodies which may be dissolved in the'oil. The hypochlorite treatment is usually preceded by a preliminary alkali wash to remove any acidic sulfur compounds which may be present. In some cases-it may be desirable to precede the hypochlorite treatment with a combination of alkali wash and adoctor sweetening step. As is well known in the art, the term doctor sweetening is applied to the treatmentof'sour distillates with sodium plumbite. Following the preliminary caustic and/or sodium plumbite treatment of the sour distillate, the distillate is treated or washed with an aqueous hypochlorite solution, preferably an alkali metal hypochlorite solution, such as sodium hypochlorite or an alkaline earth hypochlorite solution, such as calcium hypochlorite. As aforementioned, the treatment with the hypochlorite solution is usually followed with an alkali wash, such as with an aqueous caustic soda solution, to remove any acidic bodies whichmay be dissolved in the oil. In some cases, it may be found desirable to follow the hypochlorite wash with a doctor solution treatment.

Some petroleum distillates, even though subjected to drastic caustic treatment fail to pass the copper strip test; that is, will cause excessive copper staining.

The copper strip test, usually used to determine whether the treated distillates meet certain specifications, is carried out by placing a clean strip of polished pure copper in a clean test tube and adding a sufficient amount of the sample to completely cover the strip. The test tube is closed with a vented stopper and placed in an upright position in a suitable bath, maintained at the specified temperature, and at the end of a specified test period the strip is removed from the test tube, dried and compared with standard copper strips for visual rating expressed as corrosion number. A corrosion number of 12 denotes a scaley. block strip indicative of a very corrosive sample, while a corrosion number of 0 denotes an unstained strip which is indicative of a non-corrosive sample; strips having varying degrees of staining are given intermediate and numerical corrosion number ratings. A corrosion number rating higher than 7 is not satisfactory and for many specifications a corrosion number rating of 3 or less is required. A description of the copper strip test and the determination of corrosion number ratings can be found in the article by J. A. Bolt entitled, Copper strip corrosion test, published in the Oil and Gas Journal, August 4, 1947.

Depending on the specifications for any particular distillate the duration of the test varies and may be for as short as 10 minutes and as long as 24 hours. Likewise, the temperature at which the test is made varies depending upon the specification requirements from l22dF. to the initial boiling point of the distillate being teste The present invention will be described in connection with the treatment of a particular stock which is given by way of example and is not to be construed as limiting the scope of the invention.

Three separate batches of a petroleum distillate having a distillation range of between about 315 F. and 390 F. were treated in the following manner:

Each batch was given a 12 hour 20 Baum caustic wash at a temperature of to F. and then given a 48 hour doctor treatment using a fresh batch of new doctor solution after the first 24 hours contact. After the doctor treatment the batches were given a cold water wash and the temperature of the batches reduced to 85 F. Water-washed batches were then treated with an alkaline sodium hypochlorite solution using a 1 to 7 volume ratio of hypochlorite to oil; each batch was so-treated Patented Feb. 15, 1955 un il the oil was sweet and then given a hour water wash. At this stage the three batches of oil showed residual chlorine contents of 141, 153 and 195 parts per million and each had a copper strip corrosion number rating of 9 with a definite violet-blue cast.

Following the ten hour water wash, the batches were given an eight hour contact with a sodium plumbite solution. After the sodium plumbite treatment the batches had residual chlorine contents of 35, 74 and 41 parts per million, respectively, and had copper strip corrosion numbers of 6 to 7; these were unsatisfactory. The

addition of about 0.007% morpholine to the batches containing 35 and 41 parts per million chlorine resulted in products having passing copper strip corrosion numbers of 2-3, while the addition of about 0.009% morpholine to the batch having 74 parts per million chlorine resulted in the product having passing copper strip corrosion number of 3.

The terms lower-boiling hydrocarbon oil distillates and lower-boiling petroleum distillates as used herein means normally liquid distillates having maximum boiling points below about 700 -F.

While I have described my invention by reference to a specific embodiment thereof, the invention is not limited by the same but includes within its scope such modifications as come within the spirit of the appended claims.

I claim:

1. A normally liquid petroleum oil having a chlorine content of at least about 10 parts per million and normally causing copper staining containing from about 0.0001 to about 0.5% of morpholine.

2. A normally liquid petroleum distillate having a chlorine content of at least about 10 parts per million and normally corrosive to copper, containing morpholine in small but sufiicient quantities to inhibit copper cor- IOSlOIl.

3. A petroleum distillate sweetened by treatment with a chlorine-containing reagent and having a chlorine content of at least about 10 parts per million, which sweet ened distillate is normally corrosive to copper, containing from about 0.0001% to about 0.5 morpholine.

4. A hypochlorite sweetened petroleum distillate oil having a chlorine content of at least about 10 parts per million and normally corrosive to copper, containing from about 0.0001 to about 0.5% morpholine.

5. A cracked petroleum distillate oil having a chlorine content of at least about 10 parts per million and which normally causes copper staining, containing from about 0.0001% to about 0.5% morpholine.

6. A normally liquid cracked petroleum distillate sweetened with an alkali hypochlorite and having a chlorine content of at least about 10 parts per million, containing from about 0.000l% to about 0.5 morpholine.

7. A normally liquid cracked petroleum distillate sweetened with a sodium hypochlorite and having a chlorine content of at least about -10 parts per million, containing from about 0.000l% to about 0.5% morpholine.

8. A normally laifiuid cracked petroleum distillate, sweetened with an aline earth hypochlorite and having a chlorine content of at least about 10 parts per million, containing from about 0.0001% to about 0.5% morpholine.

9. A normally liquid cracked petroleum distillate, sweetened with a calcium hypochlorite and having a chlorine content of at least about 10 parts per million, containing from about 0.0001% to about 0.5% morpho- 10. The method of inhibiting the copper staining effect of a normally liquid petroleum oil having a chlorine content of about 10 parts per million, comprising incorporating in said petroleum distillate from about 0.0001% to about 0.5% of morpholine.

11. The method of substantially inhibiting the corrosion of copper by a petroleum distillate, sweetened by treatment with a hypochlorite solution having a chlorine content of at least about 10 parts per million, comprising incorporating in said sweetened petroleum distillate morpholine in small but sufiicient quantities to substantially inhibit the corrosion to copper by said sweetened petroleum distillate.

12. In the sweetening of a normally liquid petroleum distillate with a hypochlorite solution, whereby a sweetened distillate containing at least 10 parts per million chlorine and normally susceptible to copper staining is obtained, the improvement comprising incorporating in said sweetened distillate from about 0.0001% to about 0.5% morpholine.

13. In the method of treating a sour cracked petroleum distillate comprising washing said sour petroleum distillate with caustic soda, treating the caustic soda-washed distillate with a sodium plumbite solution; treating the sodium plumbite treated distillate with a hypochlorite solution and washing the hypochlorite-treated distillate with a sodium plumbite solution, whereby a sweetened distillate containing at least 10 parts per million chlorine and normal1y susceptible to copper staining is obtained, the mprovement comprising incorporating in said treated distillate from about 0.000l% to about 0.5 morpholine, wlherebfi a sweetened distillate non-staining to copper is o talne References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. A NORMALLY LIQUID PETROLEUM OIL HAVING A CHLORINE CONTENT OF AT LEAST ABOUT 10 PARTS PER MILLION AND NORMALLY CAUSING COPPER STAINING CONTAINING FROM ABOUT 0.0001% TO ABOUT 0.5% OF MORPHOLINE.