US2787531A - Stabilized petroleum naphthas - Google Patents

Description

tates 2,787,531 STABILIZED PETROLEUM NAPHTHAS Weldon Grant Annable, Mundelein, Le Roi E. Hutchings, Lakewood, and John W. Walsh, Chicago, Ill., assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio No Drawing. Application May 22, 1953, Serial No. 356,890

3 Claims. (CI. 44-78) tion of crude petroleum, a large number of chemical articles of commerce, in addition to the more conventional petroleum-derived products, such as gasoline, kerosene, diesel fuels, lubricating oils, etc, have their inception in petroleum. The less conventional articles range from pure hydrocarbons to highly complex synthetic resins and elastomers. While in some instances the chemicals directly obtained from petroleum are employed as chemical intermediates in further manufacture, 'a large number of chemical materials produced'from petroleum have direct application. The latter includes the petroleum naphthas which have a wide variety of commercial uses in the rubber, protective coating, extraction and other miscellaneous industries. The most widely used of the petroleum naphthas are the straight run products which are selected fractions of the lighter, more volatile constituents of crude petroleum. It is with these naphthas that the instant invention is concerned. Accordingly,

atcnt C Because of the diverse nature of the chemical comp I V "ice ture and sale of special naphthas. The test consists of the addition of -a small copper coupon to an A. S. T. M. distillation flask containing 100 cc. of the naphtha sample. The coupon is vertically positioned within the flask so that one end of the strip will dip into the residue at the end of the distillation. This distillation, except for the presence of the copper strip, is conducted exactly as specified in A. S. T. M. D86-38 for the distillation of gasoline, naphtha, kerosene and similar petroleum products described in A. S. T. M. Standards on Petroleum Products and Lubricants, published by American Society for Testing Materials, Philadelphia, Pennsylvania. The color of the strip upon completion of the test is indicative of the amount of corrosive sulfur which is present. Blackening the strip in this test is indicative of the presence of obnoxious sulfur compounds and the result is interpreted as unsatisfactory or positive. If the copper strip employed in the Distillation-Corrosion test is not tarnished or is slightly tarnished, these conditions indicate that the naphtha is satisfactory and the test results are termed negative. Between these two results there is an area which is termed borderline and a copper strip which is moderately tarnished or slightly colored, as evidenced by the peacock appearance of the strip, is neither definitely satisfactory nor unsatisfactory. In order to avoid a rejection of naphthas as being unsatisfactory on this basis, suppliers of naphthas encountering this condition 'generally will not market this type of product and will either reprocess the naphtha to provide a material which will give a satisfactory Distillation-Corrosion test or else will market the oil-specification product to a consumer'who is not particularly interested in purchasing a petroleumfuture reference to naphthas will connote these particular petroleum products.

Unfortunately, in the case of naphtha manufacture, crude petroleum is notsimply a mixture of hydrocarbons. It also contains other types of organic and inorganic constituents which necessitate the additional refining of straight run naphthas produced from crude petroleum to eliminate the deleterious effects of various of these constituents in order that the naphthas may conform with the exacting specifications established by industry. Generally the most inimical of the non-hydrocarbon constitu' cuts are sulfur and the sulfur-containing compounds. These materials have a disadvantageous effect on the quality of the product because they have an objectionable odor and their presence in a blended pro-' tective coating formulation may cause darkening of the finished product. Inaddition, several species of the sulfur compounds are corrosive agents. among the numerous tests which are used to control the properties and insure uniform quality, are several tests which are used for qualitatively and quantitatively determining the presence of obnoxious sulfur compounds. These are the various copper strip corrosion tests as Well as the well known Doctor test. Sulfur contents and sulfur distributions are determined in accordance with established A. S. T. M. procedures. Although odor is an important property,'there is no standard test which covers this property andthe odor of a completely refined petroleum naphtha is usually termed normal or sweet. Probably the most critical and rigorous qualitative test for determining the effect of sulfurous compounds present in the naphtha is a copper strip corrosion test, which will hereinafter be referred to as the Distillation-Corrosion test. This test, which is variously known as the full boiling range corrosion test, Amsco corrosion Included -of obnoxious sulfur compounds.

tes t, or Philadelphia test, is widely usedin the manufacnaphtha which will satisfactorily pass the Distillation- Corrosion test. Either of these alternatives results in an economic disadvantage for the petroleum naphtha producer.

Accordingly, it is an object of this invention to stabilize a naphtha which is borderline with respect to the Distillation-Corrosion test to provide a satisfactory naphtha product which will successfully meet the requirements of the Distillation-Corrosion test.

This and other advantages of the instant invention will be apparent from the following discussion of the invention.

As it has been pointed out above, it is necessary to chemically refine naphtha distillates produced from crude petroleum in order to produce finished products which are suitable for industrial use. There are several types of treating processes which are employed by the refining industry for processing naphthas to mitigate the effect These include extraction processes in which the sulfur compounds are removed from the petroleum distillate in an extraction process employing an aqueous or alcoholic caustic solution containing various mercaptan solubility promoters as the extraction medium. Examples of these processes are the well known Tannin Solutizer, Unisol and Mercapsol processes. Another type of process oxidatively converts the mercaptans contained in the petroleum distillates to disulfides. This type of process is termed oxidative sweetening and is illustrated by the conventional doctor treating process as well as the various copper sweetening processes which employ compounds of copper as oxidiz ing reagents. Inasmuch as itis generally requiredthat petroleum naphthas be doctor sweet, the chemi'calrefining of straight run naphtha distillates generally eniploys the oxidative sweetening type of process in the finishing of naphthas. Although a naphtha which is treated in this manner will be doctor sweet, this does not necessarily mean that the product will satisfactorily pass the Distillation-Corrosion test. Although satisfactory naphthas are produced in this manner, quite freesperimentallv y:

quently, depending upon the type of crude that is being processed, petroleum naphthas which have been oxidatively sweetened will give borderline results when subjected tothe Distillation-Corrosion test. Thus, where a negative result with regard to the Distillation-Corrosion test is an absolute criterion, these borderline naphthas cannot be sold for premium prices and must be downgraded and sold as off-specification products. This obviously should be avoided if possible in the treating stage. However, many refineries are not equipped with treating processes which can be used to severely treat petroleum naphthas to insure their successfully passing the Distillation-Corrosion test or, more often, the vagaries of the more conventional type of sweetening processes result in the production of borderline products.

According to this invention, it has been found that a borderline petroleum naphtha may be stabilized to provide. a material which will satisfactorily pass the Distillation-Corrosion test by the addition of a small amount of an organic hydroxy compound to the borderline prodnet. It has been found that the following liquid, organic hydroxy compounds, free from substituent groups other than specifically noted, are effective, either alone or in admixture:

(l) Aliphatic mono and dihydroxy alcohols having 8 to '18 carbon atoms per molecule, such as octyl, lauryl, cetyl alcohols and 2-hexane diol-1,3.

(2) Mono-hydroxy substituted mononuclear aromatic hydrocarbon compounds having 9 to 18 carbon atoms per molecule, such as the trialkyl phenols having 9 to 18 carbon atoms per molecule, e. g., dietertiary butyl cresol.

(3) Alkoxy alkylated phenols such as isomers of butyl hydroxyl anisole and mixtures thereof.

(-4) Mono-hydroxy substituted polynuclear aromatic hydrocarbons having 2 and 3 fused rings, such as alpha and beta naphthol. lnaddition to having the foregoing structuralcharacteristics, the useful stabilizers are also distinguished by having boiling points which are equal to or above that of the naphthas and, in addition, have molecularweights highenoughto insure that thestabilizer is soluble in thepetroleumnaphtha.

Antioxidants and staln'ligers disclosed in. the patent literature narrow boiling ranges. which find use as extraction solvents and paint diluents as well as in the compounding of rubber products.

To demonstrate the instant invention, Stoddard solvent having a boiling rangeof 300 to 385 E, which was produced as a straight rim naphtha and conventionally refined by oxidative sweetening in a copper chloride process, gave borderline results in the DistillatiomCorrosion test. The addition of'at least one of any of'the following organic hydroxy compounds to separate portions of this naphtha produced a satisfactory naphtha with respect to the Distillation-Corrosion test? octyl, cetyl and lauryl. alcohol Z-ethyl hexandiol-l,3; alpha and beta naphthol; tributyl phenol; mixtures of 2 and 3 tertiary butyl-4-hydroxyanisole having a major portion of the 2 isomer. Where the substances were liquid, 0.2 cc. of stablizer per 100 cc. of naphtha were used. If the material was solid, 0.01 grams per 100 cc. of naphtha were used in most instances. Beta napthol, however, was found to be effective in amounts as low as 0.001 grams per 100 cc. i

From the foregoing illustrative examples it will be noted that the-hydroxy compounds which will function effectively in stabilizing petroleum uaphthas, which would give borderline DistillationCorrosion test results in the absence of these stabilizers, may be found in general among the oxidation inhibitors which are employed in gasoline to mitigate oxidative deterioration. It has been found, however, that if a material is an oxidation inhibitor, it does not follow a priori that this qualification alone will permit its use in the stabilization of petroleum naphthas which give borderline results in the Distillation-Corrosion test. This is illustrated by Table I in which is tabulated the results obtained in employing a plurality of materials described by the prior art as being oxidation inhibitors in a stabilizing capacity during the testing of borderline petroleum naphthas in the Distillation-Corrosion test. =lt.will be noted from this tabular summary that the compounds which were tested were unsatisfactory for effecting the stabilization of borderline petroleum naphthas.

TABLE I Compound Reasons for Negative Result ation T- hiophenol. Bntyl Alcohol- Benzyl Alcohol Urea Pentanediol Phenyl-a-naphthylamine Sustnne Dow DHA S P-30e4930 Dicyclohexyl Amine leie A'eid Trlethylene Glycol. Diethyl'ene Glyc0l Propylene Glycol.

Dimethoxytetraglyeol 400 and 600 series polyethylene glycol. I Phenylhydrazine d 's s i s l i sum 1 Proprietary gasoline antioxidants.

The optinmniquanti iesnt st bilize i be determined rig tests on mallamounts' of the naphtha. in general OiOQI per'c'e to 0.1 percent ';-by Weight maybe used, although in some instances as" little as 0.0001 weight percent may be effective; Onthe other hand. quantities as highr as l.0 percent by weight may be requiredin exceptional cases.

-Nap t a whi h may be r at by m n of thi inventinitwl deem en she: de pa-ta ge a thee-such a. .-hb :;so1 n Stoddard solvent, but also the c1 Itisthus seenthatthere has been discovered a plurality Qffidili w hff e s ui j hi s r 'v nap hawhich u ll s ubcssfully' pass the Distillation Corro sion tesjt from a nap hthfwfiicli without"stabilization iectionable to more fastidious consumers. For example, the use of alpha naphthol produces a color, whereas the use of octyl alcohol produces a naphtha having a perceptible odor. It has been found, however, that if it is desired to produce an odorless and colorless naphtha which will successfully pass the Distillation-Corrosion test from a naphtha which gives borderline results in the Distillation-Corrosion test in the absence of a stabilizer, the desirable stabilizing material to use would be beta naphthol.

It will be understood that it is intended that all changes and modifications of the examples of the invention herein chosen for the purposes of illustration which do not depart from the spirit and scope of this invention are covered by the appended claims.

What is claimed is:

1. A petroleum naphtha characterized by providing satisfactory results in the Distillation-Corrosion test which comprises a major portion of an oxidatively sweetened petroleum naphtha which produces borderline results in the Distillation-Corrosion test and a minor portion in an amount sufiicient to abate the corrosive tendencies of said naphtha as determined by said Distillation-Corrosion test of at least one naphtha soluble, organic, hydroxy compound selected from the group consisting of octyl alcohol, cetyl alcohol and lauryl alcohol, 2-ethyl heXanediol-1,3, ditertiary butyl cresol, mixtures of 2 and 3 tertiary butyl-4-hydroxyanisole having a major portion of the 2 isomer, and alpha and beta naphthol.

2. A naphtha in accordance with claim 1 in which the organic, hydroxy compound is present in an amount of 0.001-1% by Weight.

3. A petroleum naphtha in accordance with claim 1 in which said organic hydroxy compound is beta naphthol.

References Cited in the file of this patent UNITED STATES PATENTS Schulze Aug. 10, 1937 Wilson et a1. July 15, 1941

Claims (1)

1. A PETROLEUM NAPHTHA CHARACTERIZED BY PROVIDING SATISFACTORY RESULTS IN THE DISTILLATION-CORROSION TEST WHICH COMPRISES A MAJOR PORTION OF AN OXIDATIVELY SWEETENED PETROLEUM NAPHTHA WHICH PRODUCTS BORDELINE RESULTS IN THE DISTILLATION-CORROSIONTEST AND A MINOR PORTION IN AN AMOUNT SUFFICEINT TO ABATE THE CORROSIVE TENDENCIES OF SAID NAPHTHA AS DETERMINED BY SAID DISTILLATION-CORROSION TEST OF AT LEAST ONE NAPHTHA SOLUBLE, ORGANIC, HYDROXY COMPOUND SELECTED FROM THE GROUP CONSISTING OF OCTYL ALCOHOL, CETYL ALCOHOL AND LAURYL ALCOHOL, 2-ETHYL HEXANEDIOL-,3, DITERTIARY BUTYL CRESOL, MIXTURES OF 2 AND 3 TERTIARY BUTYL-4-HYDROXYANISOLE HAVING A MAJOR PORTION OF THE 2 ISOMER, AND ALPHA AND BETA NAPHTHOL.