US3597173A - Oxidative treatment of petroleum distillate fuels containing olefinic unsaturated components - Google Patents

Abstract

PETROLEUM DISTILLATE FUELS CONTAINING OLEFINS AND DISSOLVED MOLECULAR OXYGEN ARE TREATED WITH FROM 0.1 TO 1.0 WT. PERCENT OF AT LEAST ONE ARYLHYDRAZONE, PREFERABLY THE ARYLHYDRAZONE OF A CYCLO ALIPHATIC SATURATED HYDROCARBON KETONE, AFTER WHICH BOTH THE INSOLUBLE AND SOLUBLE GUMS ARE SEPARATED FROM THE SO TREATED FUELS.

Description

United States Patent ice US. Cl. 44-64 ABSTRACT OF THE DISCLOSURE Petroleum distillate fuels containing olefins and dissolved molecular oxygen are treated with from 0.1 to 1.0 wt. percent of at least one arylhydrazone, preferably the arylhydrazone of a cyclo aliphatic saturated hydrocarbon ketone, after which both the insoluble and soluble gums are separated from the so treated fuels.

The present invention relates to the oxidative treatment of petroleum distillate fuels containing olefinic unsaturated components and, more particularly, relates to the stabilization of such fuels especially those having boiling points within the range of between about 75 F. and about 750 F. whereby it is possible to improve the stabil ity of such fuels and to thus greatly alleviate the gum forming tendencies of such fuels when stored or stand ing under atmospheric conditions and in contact with the atmosphere.

The petroleum industry has long recognized the instability of distillate petroleum fuels, boiling between about 75 F. and about 750 F. or having boiling ranges within this range, largely due to the presence of olefinic unsaturated components in such fuels. This constitutes a serious problem in connection with the use, handling, and storage of the fuels because the unstable constituents chief among which are the mono and diolefinic components, tend to gradually oxidize or otherwise react. For example, polymerization or copolymerization occurs during storage to form gums, sludges, and/or sediments which either precipitate out of the fuel of which remain in solution in the fuel and are later deposited through vaporization or combustion of the fuels in fuel lines, carburetors, pistons, cylinder walls and other surfaces in internal combustion engines thus causing breakdown in lubrication and a general gumming up in internal combustion engines. Such clogging and deposition of either precipitate or dissolved gums or sludge which have formed as a result of the co-oxidation or oxidation of the olefinic components necessitates the disassembling of the engine and the cleaning of all moving parts including carburetors, fuel lines, filters and the like. This becomes an extremely expensive operation and entails time consuming effort. In the past, this has sometimes been controlled to some extent through the addition of antioxidants to the petroleum distillate fuels containing the olefinic components.

The present invention provides a new and improved method of treatment of such unsaturated petroleum distillate fuels in order to accelerate under controlled proce dures and conditions, the formation of gum and sludge which is thought to be brought about by polymerization and copolymerization of the olefinic components through the peroxidation and/or oxidation, of these components whereby both soluble and insoluble gums and sludges are formed. It is, of course, readily apparent that once the major portion of those olefinic components having the greatest tendency towards oxidative polymerization and/ or copolymerization are removed as insoluble solids by centrifugation and the like or by vaporization to isolate 3,597,173 Patented Aug. 3, 1971 the potential gums which are dissolved in the fuels, the resultant distillate fuel is, to a large extent, stabilized.

The novel treatment involves the addition of between about 0.1% and about 1.0%, preferably between about 0.3 Wt. percent and about 0.6 Wt. percent of one or more specific arylhydrazones. Another requirement is that mo lecular oxygen, i.e., air, be either dissolved in the fuels so treated or at least the fuels should be in contact with molecular oxygen such as in the form of air. Depending upon the relative hydroperoxidic activity of the particular hydrazone or hydrazones employed and depending upon the temperature employed, which may range from atmospheric up to about F. or thereabouts, the time of contact required to achieve substantial oxidative reaction of the olefinic components may range from about 30 minutes up to several hours, for example, up to 8 or 50 hours or even longer. In general, however, atmospheric temperatures and pressures are entirely suitable for effecting the oxidative polymerization and/or copolymerization of the olefinic constituents. A mere settling operation followed by decantation, centrifugation, or filtration will remove the solid gums thus leaving a fuel containing only potential or dissolved gum. A subsequent atmospheric or vacuum distillation, if convenience dictates, will result in a distillate product substantially free of both solid and dissolved gum. It has been found that fuels so treated are effectively stabilized against further oxidation. If necessary, prolonged periods of storage of the so treated fuels in the presence of conventional antioxidants such as 2,6-di-tertiary butyl phenol, p-amino phenol, di-phenylamine and N,N-di-secondarybutyl-p-phenylene diamine, when added in amounts up to .01 wt. percent, results in stable fuels over prolonged periods of time, i.e., of the order of many weeks and, in fact, months.

The arylhydrazones employed are those having the formula:

wherein R may be a C C saturated acyclic hydrocarbon radical such as methyl, ethyl, isopropyl, propyl, butyl, isobutyl, octyl, iso-octyl, dodecyl and the like or may further be a C -C saturated cyclic aliphatic hydrocarbon radical such as cyclopentyl, cyclohexyl, cycloheptyl and the like, and aralkyl radical such as benzyl, phenethyl or an aryl radical such as phenyl, naphthyl, or anthryl. R

may be the same as or different from R as above defined,

R and R may be jointly a C -C alkylene (cycloaliphatic) radical or R may be hydrogen. It has been discovered, however, that R may not be an aryl radical if R is also an aryl radical. The arylhydrazine reacted with this ketonic or aldehydic compound must be an arylhydrazine such as phenylhydrazine, naphthylhydrazine, or anthrylhydrazine. Representative hydrazones employed are the phenylhydrazones of cyclohexanone, cyclopentanone, benzylaldehyde, para-tolyl aldehyde, dibenzyl ketone, acetophenone, 9-anthranaldehyde, l-naphthaldehyde, and Z-naphthaldehyde. The arylhydrazones may be formed by reacting the hydrazine with a mixed ketoaldehyde such as pivalyl aldehyde, a dialdehyde such as phthalaldehyde, or a diketone such as cyclohexanedione or cyclopentanedione. As used in this description and accompanying claims, the definitions of R and R are intended to encompass the mixed ketoaldehydes, the diketones, and the dialdehydes.

The oxidative treatment, involving the use of arylhydrazones as above described and defined, of the petroleum distillate fuels containing olefinic unsaturated components applies to a wide range of gasolines and heating oils. These may be derived from gas oils of any desired boiling range through the conventional steam cracking, thermal cracking, or catalytic cracking of the same. Almost any cracked naphtha or heating oil contains considerable quantities of olefinic compounds. These olefinic compounds, depending upon the particular process by which the naphtha was produced, can be either cyclic or acrylic in nature. They can be mono-olefinic or di-olefinic (either conjugated, nonconjugated, or of the allenic type). In some cases polymeric forms of olefins are present in the cracked naphthas as produced, generally in soluble form. Any of the cyclic or acyclic olefinic unsaturated compounds such as indene, or even styrene, will be effectively polymerized or copolymerized through the novel arylhydrazone treatment herein described. Typical olefins found in cracked naphthas and heating oils include the following: Z-heXene, cyclohexene, indenc, 1,3-hexadiene, l-pentene and 4-methyl-2-hexene. Any number of these olefinically unsaturated compounds other than those specifically mentioned tend to render gasoline or heating oils unstable during storage.

Additionally, and depending upon the source of the crude oil which has been used, these distillate fuels may also contain nitrogen compounds such as pyrroles, indoles, aliphatic amines and pyridines, disulfides, and finally mercaptans of both aliphatic and aromatic nature, Although it is not intended that the instant novel process be limited by any theory, it is believed that substantial portions of these types of impurities also undergo oxidative reaction involving polymerization and/or oxidative reaction involving copolymerization of these impurities with some of the olefinc components present and so are likewise converted into gums or sludges which can be removed in the same manner and at the same time as the gums and sludges formed solely from the olefinic constituents.

The presence of other additives in the treated distillates such as antiknock agents, scavenging agents, dyes, antiicing agents, and solvent oils in total additive concentra- 4 EXAMPLE 1 A heavy catalytic cracked naphtha of the type above stated, in aliquots, was treated with about 1 wt. percent of a number of different phenylhydrazones under the temperature and time conditions shown in Table I.

The first run shown in the table is a blank run involving no treatment with a phenylhydrazone and is shown for comparative purposes only. The comparative tests were carried out as follows:

A 500 cc., round bottom, 4-necked flask was equipped with a paddle stirrer, an overhead water-cooled condenser, a thermometer, and a self-sealing rubber cap. Molecular oxygen was supplied to the vessel from a partially filled polyethylene gas balloon, through a wet-test gas meter through which oxygen was passed, connected to a drying tower packed with a desiccating material such as Drierite (anhydrous magnesium sulfate). There was then introduced into the reaction vessel through the neck of the flask 200 to 250 cc. of naphtha and 2 to 2.5 grams of the particular phenylhydrazone, when used. The system was then purged with oxygen, sealed with the rubber cap, and the wet-test meter adjusted to Zero volume when an equilibrium pressure was established. The reaction was then started by rapid stirring and was allowed to proceed until no further oxygen consumption could be detected on the wet-test meter. All experiments were conducted at atmospheric pressure.

In the following tables, the column headed Existent Solid Gum and the column headed Soluble Gum added together give the total gum formed in the treating process; the existent gum being precipitated from the naphtha and recovered by filtration and weighed in terms of milligrams per 100 cubic centimeters of naphtha and the potential gum being soluble gum which was recovered after distilling to dryness and weighing the gum. These figures are also in terms of milligrams of gum per 100 cc. of feed.

TABLE I.PHENYLHYDRAZONE-CATALYZED DEGRADATION OF ACTUAL PETROLEUM FRACTIONS Total gum Amount Phcnylhydrazone Temp., Time, Existent Soluble Food in cc. derivative Grams hours solidgnm gum 1 Heavy catalytic naphtha 2 200 25 -24 34 844 Do 200 Benzaldehyde... 2 25 90 562 1,383 200 .do 2 70 666 1,521 200 Acetophenone 2 25 163 505 1, 004 200 do 2 25 71 370 2,820 200 do 2 50 66 1, 647 3,266 200 Indanedione 2 25 170 544 1,757 250 Cyclohexanonc 2.5 25 119 605 1,584 250 Cyclopentanone .c 2.5 25 69 273 1, 041

l Mg./100 cc. of feed; 2 Blank run.

tion not exceeding 5 %by weight does not adversely affect At 25 C., benzaldehyde phenylhydrazone and acetothe oxidative treatment with arylhydrazones for the purphenone phenylhydrazone increased existent gum 11- to pose of forming gums. Conversely, the treatment with 17-fold and potential gum 1.2- to 3.3-fold. When the arylhydrazones does not adversely affect the functioning temperature was increased to 50 C., no appreciable of the aforementioned conventional additives for their in increase in gum was observed with benzaldehyde phenyltended purpose, so that it is possible to successfully carry hydrazone but, with acetophenone phenylhydrazone, eX- out the oxidative gum formation operation on either te gum Was increased 48-fold and potential gum was finished or unfinished gasolines or heating oils, which concreased 4-fold. Indanedione phenylhydrazone, though wi th l fi i components considerably less reactive than benzaldehyde phenylhydra- Representative specific types of naphthas and heating ZOI1e and acetophenone phenylhydrazone in the rate oils to which the invention applies are heavy catalytic Studles, Pr e a 15-f ld increase in existent gum and naphthas, light catalytic naphthas, #2 heating oil and the a Increase in Potential1 gum after 170 hours 0f like. Typical and representative chemical and physical oxidation at 25 C. Similar results were obtained when inspections of two such naphthas are as follows: cycloheXanOne phenylhydrazone and cyclopentanone phenylhydrazone were added to the heavy naphtha frac- Heavv L h tion. No appreciable reaction (gum formation) was obcatalytic catalytic naphtha naphtha served when either the benzophenone phenylhydrazone or Gravity, A31 25 fl ne ph nylhydrazone was employed as the ox1da- Initial boiling point, 0 F 430 77 tion polymerization catalyst. Final boiling point, F. 650 430 Research octane numben. 55 EXAMPLE 2 Wt. percent aromatics c. 47.1 11.3 Wt. pelii'cent mono olefins-diolefins (cyclic plus 26 III a manner similar [0 that described in Example 1,

.3 57.8 w g rgent saturates (cyclic plus acyclic) 26.6 30. 9 a light catalytlf: naphtha haVmg the Inspect)? above stated was treated with various phenylhydrazones 1n the amount of about 1.0 wt. percent. Table II shows the temperature and time conditions employed and the amount of solid and soluble gum formed as a result of the treatment.

hydrazone of cyclohexanone proved to be highly effective in catalyzing gum formation of both the soluble and insoluble type.

TABLE II.PHENYLHYDRAZONE-CATALYZED DEGRADATION OF ACTUAL PETROLEUM FRACTIONS Table Gum Amount Derivative of Temp., Time, Existent Soluble Feed in cc. phenylhydrazone Grams C. hours solid gum gum Light catalytic naphtha 25 -24 6. 6 308 Do 2 25 72 346 853 2 50 96 632 1,017 2 50 117 524 1, 102 t 2. 4 25 70 678 200 Acetophenone 2 25 67 308 697 200 Q-anthranaldehyde 4 3 25 115 825 250 cyclohexanone 2. 66 363 814 200 do 2 25 71 560 1,361

1 Mg./100. 2 Blank run. 3 Recovered 2.1 grams para-nitro benzaldehyde phenylhydrazone. 1 Recovered 3.0 grams Q-anthranaldehyde phenylhydrazone.

Autoxidation of the light naphtha fraction in the pres- EXAMPLE 4 ence of benzaldehyde phenylhydrazone and acetophenone phenylhydrazone produced a 47- to 53-fold increase in existent gum and a 2.3- to 2.6-fold increase in potential gum at 25 C. With benzaldehyde phenylhydrazone at 50 C., existent gum was increased 80- to 105-fold and potential gum was increased 3-fold. 9-anthranaldehyde phenylhydrazone and n-nitrobenzaldehyde phenylhydrazone did not increase existent gum but they did increase potential gum by a factor of 2 to 3. In the presence of cyclohexanone phenylhydrazone existent gum was increased by a factor of 53 to 85 and potential gum was increased by a factor of 2.7 to 4.4. These results were obtained after 66 to 71 hours of reaction.

The above data show that for the examples cited, cyclohexanone phenylhydrazone is the most effective catalyst. The data also show that electron withdrawing groups, e.g., nitro, attached to the nucleus of the phenylaldehyde phenylhydrazone, decrease phenylhydrazone reactivity and that an increase in aromaticity of the aryl group of the aldehyde used results in a decrease in reactivity, i.e., benzaldehyde phenylhydrazone and acetophenone phenylhydrazone are more effective catalysts than 9-anthranaldehyde phenylhydrazone.

EXAMPLE 3 A regular commercially available catalytically cracked gasoline having a boiling range of 100-350 F. and a Research Octane Number of 87 and having a chemical composition of 45 wt. percent of cyclic plus acyclic olefins and diolefins, wt. percent of aromatics and 25 wt. percent of parafiins and naphthenes was treated with cyclohexanone phenylhydrazone in the manner described in Example 1. Table III shows the amount of precipitated gum and soluble gum obtained in each case:

A mildly hydrotreated steam cracked naphtha of about 140 F. initial boiling point and about 480 F. final boiling point, having about 16 wt. percent total ole-finically unsaturated hydrocarbons, about 44 wt. percent of aromatics with the balance being parafiinic constituents, was employed.

300 cc. of this naphtha was treated in the manner described in Example 1 at 25 C. for 47.0 hours with 3.0 grams of the phenylhydrazone derivative of benzaldehyde. The reacted mixture was worked up and analyzed in the same manner as described in Example 1.

The bromine number of the feedstock was 86.1 and the product, after co-oxidation, had a bromine number of 80.0. The fresh naphtha contained 42 mg. per 100 cc. of feed of solid gum and 2177 mg., on the same basis, of potential or soluble gum. The treated naphtha contained 922 mg. and 4188 mg, respectively, of solid and soluble gum, on the same basis. This represents, by the treatment, a two-fold increase in soluble gum and a 22-fold increase in solid or existent gum and gives a treated naphtha, after separating of both types of gum, of vastly increased stability in storage.

The arylhydrazones used in the instant novel process are readily formed by conventional processes. One process involves the reaction of a ketone or an aldehyde with the particular arylhydrazine in equimolar amounts in a solvent such as ethanol for a period of time between about 1 and 24 hours and at a temperature of between about 32 F. and about 212 F. A trace of acetic acid or sulfuric acid is employed as the catalyst. The solidified arylhydrazone precipitates from the solution is collected by filtration, dried, and is then ready for use in the instant novel process. Any conventional method may be employed in the production of the arylhydrazones and TABLE IIL-PHENYLHYDRAZONE-CATALYZED DEGRADATION OF ACTUAL PETROLEUM FRACTIONS Total gum Existent Soluble Amount Derivative oi Temp, Time, solid (potential) Feed in 0.0. phenylhydrazone Grams 0. hours gum gum 1 Regular gasoline 1 25 -24 6. 6 363 Do 25 140 333 753 Do 25 51 122 766 1 Mg./100 cc. of feed. 7 Blank run.

a 0.5 wt. percent. 4 0.1 wt. percent.

In the presence of between about 0.1 and about 0.5 wt. percent of cyclohexanone phenylhydrazone, potential gum was increased by a factor of 19 to 50 and existent gum was increased by a factor of about 2.

It will be seen that in this particular treatment of a regular commercially available gasoline that the phenylrated herein by reference.

Having now thus fully described and illustrated the instant novel process, what is desired to be secured by Letters Patent is:

1. A process which comprises treating, in the liquid phase, a petroleum distillate fuel containing olefinic unsaturated components, in the presence of molecular oxygen, with between about 0.1 and 1.0 wt. percent of at least one phenylhydrazone selected from the group consisting of the phenylhydrazone of cyclopentanone, the phenylhydrazone of cyclohexanone and the phenylhydrazone of acetophenone, and separating the resultant insoluble gums from the so treated fuel.

2.. A process as in claim 1 wherein the distillate fuel is a cracked naphtha boiling within the range between about 75 F. and about 750 F.

OTHER REFERENCES The Chemistry of Hydrazine Audrieth et al., Copyright, 1951, John Wiley & Sons, Inc., pp. 226-227.

10 DANIEL E. WYMAN, Primary Examiner Y. H. SMITH, Assistant Examiner US. Cl. X.R.