US3485604A - Stabilization of petroleum distillates containing olefins - Google Patents

Description

United States Patent US. C]. 4464 9 Claims ABSTRACT OF THE DISCLOSURE Solids-free petroleum distillate fuels which are resistant to further atmospheric oxidation are obtained by treating petroleum distillate fuels which originally contained olefinic unsaturated components and molecular oxygen, i.e., air, with at least one metal chelate, the metal having an atomic number between 23 and 29 inclusive, and being formed from a beta diketone, and at least one arylhydrazone followed by the removal of at least the resultant solid gum formed thereby by suitable means, such as settling, decantation, centrifugation, filtration and/or distillation.

The present invention relates to the stabilization of petroleum distillate fuels containing olefinic unsaturated components through an oxidative treatment. In particular, it relates to the stabilization of fuels having boiling ranges within the range of between about 75 F. and about 750 F. whereby it is possible to improve the stability of such fuels by oxidative degradation and to thus greatly alleviate the gum forming tendencies of such fuels when stored or standing under atmospheric conditions and in contact with either air or molecular I oxygen.

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 or 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 of 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.

In copending applications, Ser. No. 517,908 filed J an.

3,485,604 Patented Dec. 23, 1969 3, 1966 by Thomas J. Wallace and Norman Friedman entitled Oxidative Treatment of Petroleum Distillate Fuels Containing Olefinic Unsaturated Components, and Ser. No. 518,033 filed Jan. 3, 1966 by Ellie A. Vogelfanger and Thomas J. Wallace entitled Stabilization of Petroleum Distillate Fuels by Oxidative Treatment, new and improved methods of treating such unsaturated petroleum distillates are disclosed and claimed. These disclosures show that in order to accelerate the formation of gum and sludge through polymerization and/or copolymerization of the olefinic components in distillate fuels, certain arylhydrazones with or without the cotreatment with a metallocene are added. It is shown therein that once the major portion of the readily oxidizable and polymerizable olefinic components are removed as polymers, either soluble or insoluble in nature, the resultant distillate fuel is stabilized against further atmospheric oxidative degradation to a large extent. In those applications it is directed to add between about 0.1 and about 1% by weight, preferably between about 0.3 wt. percent and about 0.6 wt. percent, of one or more specific arylhydrazones, with or without metallocenes, in the presence of molecular oxygen, i.e., air, which may either be dissolved in the fuels or in contact with the fuels during such treatment. Neither the time of contact nor the temperature is critical in such treatmens but it is preferred to use a temperature of from atmospheric up to about F. for a sufiicient time of contact of the arylhydrazones, with or without metallocenes, with the olefinic feedstocks to allow for substantial Oxidative polymerization or copolymerization of the olefinic constituents thereof. The time of contact may range anywhere from between about 30 minutes up to several hours, for example, up to 8 to 50 hours or even longer. The length of time is generally that amount of time during which substantial quantities of oxygen are consumed or taken up in the reaction. It has subsequently been discovered that this may last up to 172 to 200 hours where atmospheric temperatures are employed.

Following the treatment the solid or existent gums are removed by settling, decantation, centrifiguration, or filtration. A subsequent atmospheric or vacuum distillation, if convenient, will result in an overhead distillate or condensate substantially free of potential or soluble gum, the residue containing such gum. Fuels so treated are effectively stabilized against any further substantial Oxidative reactions and so they remain stable over prolonged periods of time and during actual use. If desired, they may be stabilized against further oxidation by the use of conventional antioxidants as additives thereto. Such antioxidants, for example, are: 2,6-di-tert-butylphenol, para-aminophenol, diphenylamine, and N,N-disecondary-butyl-para-phenylenediamine. Conventionally these are added in amounts up to about 0.01 Wt. percent and thus effect stabilized fuels which remain so over long periods of time of the order of many Weeks or months.

The arylhydrazones employed, and which are employed in the instant novel process also, 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, an 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 anaryl radical. The arylhydrazine reacted with this ketonic or aldehydic compound must be an arylhydrazine such as phenylhydrazine, napthylhydrazine, or anthrylhydrazine. Representative hydrazones employed are the phenylhydrazones of cyclohexanone, cyclopentanone, benzylaldehyde, para-tolylaldehyde, 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.

It has now been discovered that even greater and even more improved rates of oxidation with resultant polymerization and copolymerization of the olefinic constituents can be accomplished and even greater amounts of existent and potential gums formed if there is also used, in conjunction with the hydrazones mentioned above, an effective amount of one or more metal chelates. The amount of chelate may vary considerably but, in general, the distillate fuel being treated may contain an arylhydrazone to metal chelate weight ratio of between about 1:1 and about 10:1, preferably between about 3 :1 and about 6:1. Larger amounts of metal chelates may be employed with regard to the amount of arylhydrazones used, but, because of the cost of the chelates, the rate of oxidation and the total amount of polymerization or copolymerization of the olefinic constituents is not sufficiently increased to warrant the extra expense of using the larger amounts of the metal chelates; the total amount of mixed treating agent used (hydrazone plus metal chelate) is between about 0.1 and about 1.0 wt. percent, preferably between about 0.4 and about 0.7 wt. percent. The two types of additives may be premixed and added to the fuel or other petroleum distillate or either one may be first added and the other one subsequently added. Mixtures of two or more of the above defined hydrazones and of two or more of the hereinafter defined metal chelates may also be employed.

The metal chelates, it has been found, must be of a rather limited class in order to accomplish the desired purpose. Not all metal chelates are operable for the intended use. For example, the metal portion of the chelate must be a metal having an atomic number between 23 and 29, inclusive, as defined according to the chart of the Periodic System of Henry D. Hubbard, revised edition, 1956. In other words, the metal portion of the chelate may be one or more of the following metals: vanadium, chromium, manganese, iron, cobalt, nickel, and copper. Chelates of such metals as zinc, zirconium, molybdenum, titanium, and the like are ineffective for accomplishing the purposes of this novel process.

The ligand portion of the metal chelate may be derived from any compound of the following formula:

wherein R and R are separately selected from the group consisting of hydrogen, hydroxyl, alkyl and alkoxy each of from 1 to 7 carbon atoms per radical, phenoxy, phenyl, phenalkyl, phenalkoxy, alkylphenyl and alkylphenoxy wherein the alkyl portion of these radicals also contains from 1 to 7 carbon atoms and R is selected from the group consisting of hydrogen, methyl, ethyl and propyl. Typical and representative specific compounds that may be used are the following: diethyl malonate, ethyl acetoacetate and its C-methyl derivative where the methyl is attached to the carbon atom between the two carbonyl groups, ethyl benzoyl acetate, methyl tolyl acetate, acetoacetaldehyde and acetylacetone. The last two mentioned compounds are especially useful and are preferred. Any dicarbonyl compound in which the carbonyl groups are separated from each other by a single carbon atom may be employed as the ligand but those having a tendency to tautomerize to a great extent into their enol form are especially desirable. Specifically, the R and R substituents of the ligand are intended to include: methyl, ethyl, propyl, isopropyl and butyl, methoxy, ethoxy, propoxy, isopropoxy, butoxy, phenyl, benzyl, phenethyl, tolyl, xylyl, ethyl tolyl, phenoxy and the like. It is only necessary that the ligand contain the grouping:

of the above specifically identified multivalent metal radicals.

Any suitable inorganic or organic salt of the above defined metals may be employed so long as it is soluble or relatively soluble in the specific solvent medium employed such as water, generally, but which may also be acetone or alcohol such as ethyl or methyl alcohol. Benzene may also be employed as a solvent depending upon the specific inorganic metal salt employed. In some cases solvent ethers such as butyl Cellosolve and the like are useful reaction media in forming the metal chelate. Specific chelateforming salts are the chlorides, bromides, acetates, and, in some instances, sulfates and nitrates, carbonates, chlorates and percarbonates. Specific salts which may be employed are, for example, ferrous bromide or chloride, ferric bromide or chloride, vanadium bromides and chlorides, vanadyl chloride and bromide, manganic and manganous chloride and acetates, the cobalt and nickel divalent chlorides or bromides, cuprous and cupric chlorides, cupric acetate and the like. These chelates of the multivalent heavy metals identified above are complexed with the dicarbonyl compounds. Most, if not all of them, are available as standard articles of commerce and are purchasable on the open market. Their process of production is carried out under well known and common procedures such as by adding a solution of the inorganic metal salt of a complex forming metal to a solution of the selected dicarbonyl compound followed by the addition of alkaline solution in the amount required to neutralize the acid formed as a by-product from the metal salt. The precipitated chelates are then filtered and washed to free the product of the reaction from the by-products and excess reactants which may be present. Improved methods have been employed such as that described in US. Patent No. 2,976,285 but the chelates, per se, and their method of production form no part of this invention; it being suflicient that any conventional method of forming the chelates may be employed and it being sufficient to state that the chelates so formed are well known and, for the most part, are standard articles of commerce.

The instant novel process, therefore, involves the treatment in liquid phase of a petroleum distillate fuel containing olefinic unsaturated components in the presence of either molecular oxygen or air with at least one metal chelate formed by reacting a metal salt whose metal has an atomic number between 23 and 29 inclusive, with any organic dicarbonyl-containing compound in which the carbonyl groups are separated from each other by a single carbon atom and with at least one aryl hydrazone formed by reacting an organic compound containing a single carbonyl group with an arylhydrazine.

The oxidative treatment of the petroleum distillate fuels containing olefinic unsaturated components involving the combined use of arylhydrazones and metal chelates, as above described and defined, 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 middle distillate was produced, can be either cyclic or acyclic in nature. They can be monoolefinic or di-olefinic (either conjugated, nonconjugated, or of the allylic 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, styrene, the pentadienes, hexadienes, etc., will be effectively polymerized or copolymerized through the novel arylhydrazone-metal chelate treatment herein described. Typical olefins found in cracked naphthas and heating oils include the following: 2-hexene, cyclohexene, indene, 1,3- hexadiene, 1,3-pentadiene, l-pentene and 4-methyl-2-hexene. Any number of 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 final ly 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/r oxidative reaction involving copolymerization with some of the olefinic 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 distillate's such as antiknock agents, scavenging agents, dyes, antiicing agents, and solvent oils in total additive concentration not exceeding 5% by wt. does not adversely affect the oxidative treatment with arylhydrazones and metal chelates for the purpose of forming polymeric gums. Conversely, the treatment with arylhydrazones and metal chelates does not adversely affect the functioning of the aforementioned conventional additives for their intended purpose, so that it is possible to successfully carry out the oxidative gum formation operation on either finished or unfinished gasolines or heating oils, which contain the olefinic components.

Representative specific types of naphthas and heating oils to which the invention applies are heavy catalytic naphthas, light catalytic naphthas, No. 2 heating oil, and the like. Typical and representative chemical and physical inspections of two such naphthas are as follows:

The reaction may be carried out at ambient temperatures and under atmospheric pressure in which case the gum formation is relatively slow but does, in the course of time, form large amounts of both solid (existent) and potential (soluble) gum. If desired, however, superatmospheric temperatures up to as high as 500 F. and suflicient Superatmospheric pressures to maintain liquid phase treatment may be employed. Superatmospheric pressures of up to 10 atmospheres will usually be sufiicient and the use of any higher pressures, although contemplated and useful, is generally unnecessary for accomplishing a rapid polymerization and copolymerization of the olefinic constituents in the petroleum distillate so treated. The solid polymers and copolymers are removable for filtration or centrifugation. The soluble polymers and copolymers are left in the still pot residues after distillation of the treated distillates.

The following examples are illustrative of the specific character of the novel process but it is not intended that the invention be limited thereto.

EXAMPLE 1 A heavy catalytically cracked naphtha of the type above stated, in 200 cc. aliquots, except as otherwise noted, was treated with 1 wt. percent of a phenylhydrazone plus 0.1 wt. percent of a metal acetylacetonate. For the purposes of these percentages in this example and the following examples, 200 cc. of naphtha feed or regular gasoline is considered to weigh 200 grams. All operations were carried out at ambient temperatures which ranged from 22 C. to 25 C. and at atmospheric pressure. The results and conditions of treatment are shown in Table I. The first run is a blank run in that no additive was employed. The second run is for subsequent comparative purposes involving the use of a phenylhydrazone alone. Runs 2 through 6 are also for subsequent comparison purposes and involve the use of metal chelates, of acetylacetonates as the sole additive. 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 the 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 and metal chelate, 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. The times of contact are those times deemed to have been necessary to secure substantially complete consumption of oxygen using the particular reactants and under the particular conditions obtaining at the time.

In the following tables, the column headed Existent (Solid) and the column headed Potential (Soluble) 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 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.HEAVY CATALYTIC NAPHTHA FEED (200 cc.)

Total gum (Mg/100 cc. of feed) Amount Time of Treat '11 grams contact, temp Existent Potential Run Oxidative reagent (wt. percent) hrs. (solid) (soluble) 0 Blank 24 25 34 844 1 Cyclohcxanone-phenylhydrazone. 2.0 (1.0) 72 25 605 1,584 2 Ni II acctylaeetonate I. 0. 2 (0. 1) 72. 2 395 l, 402 3 Mn III acetylacetonate 0. 2 (0.1) 72. 5 22 507 1, 608 4 Mn II acetylacetonate 0. 2 (0.1) 72.. 2 444 1,483 Co II acetylacctonate 0. 2 (O. 1) 72. 5 22 866 1, 720 6 Cu II aeetylaeetonate 0. 2 (0.1) 72. 5 22 588 1, 258

Gyelohexanone-phenylhydrazone 2.0 (1.0) 7 Cyelohexaknone-phenylhydrazona+00 lI aeetyl- O. 2 (0. 1) 71. 5 22 5, 571

acetone e. 8 I. Cyelohexanone-phenyll1ydrazone+Ni II aeetyl- 0. 2 (0.1) 71. 5 22 2, 722

acetonate 9 Cyelohexanene-phenylhydrazonc+Mn III acet- 0 2 (0.1) 71.5 22 4, 000

ylaeetonate. l0 Cyclohexanonephenylhydrazonc+Mn II acetyl- 0. 2 (0. l) 71. 5 22 3, 293

acetonate. 11 Cyelohexanone-phenylhydrazone+Cu II acetyl- 0. 2 (0.1) 71. 5 22 998 1, 695

acetonate.

The data in Table 1 show that, for a 71 to 72 hour period, the mixed atalyst systems produced 998 to 3,473 mg./l00 cc. of existent gum and 1,695 to 5.571 mg./l00

cc. of potential gum. With this feed, the acetylacetonates These figures clearly show the advantage for the mixed catalyst systems with regard to total quantity of gum. Another advantage of the mixed catalyst use is that it gives an enhanced rate of oxidation. The latter will be discussed more fully in the remaining examples.

EXAMPLE 2 In a similar manner to that described in Example 1, a light catalytically cracked naphtha having the inspection hereinbefore set forth was treated with three diflerent hydrazones in combination with several metal chelates, in this case, the metal acetylacetonates. A blank run with no oxidative reagents added and blank runs with only a phenylhydrazone or only a metal acetylacetonate were carried out for comparative purposes.

TABLE 1I.LIGIII CATALYTIC NAPIITIIA FEED (200 cc.)

Total gum (Mg/100 cc. of Iced) Amount Time 01' Treat in grams contact, temp, Existent Potential Run Oxidative reagent (wt. percent) hrs. C. (solid) (soluble) 12 Blank 24 25 6.6 308 13 Benzaldehydc phenylhydrazone 2.0 (1.0) 71 5 540 690 14." Acetophenone phenylhydrazone 2.0 (1.0) 71 25 320 727 15 Cyclohexanone phenylhydrazone... 2.0 (1. 0) 71 720 1, 205 16 Ni II Acetylacctonate 0.2 (0.1) 96 22 456 1,104 17 00 II Aeetylacctonate" 0. 2 (0. 1) 96 2 593 1,100 18 Cu II Acetylaeetonatc .2. 0. 2 (0.1) 06 22 265 857 10 M11 II Acetylacetonate. 0. 2 (0.1) 90 22 383 1,257 20, Mn III Acetylaeet0nate 0. 2 (O. 1) 06 22 236 1, 815 21 V III Aeetylaeetonate 0. 2 (0.1) 7 2 708 1,135 22 Oyclohexanone phenylhydrazone 2.0 (1.0) 71 25 560 1, 361 23 Cyclohexanone phenylhydrazone+N i II aeetyl- 0. 2 (0.1) 70 22 062 1, 537

aeetona e. 24 Cyclohexanone phenylhydrazone+Co III ace- 0.2 (0.1) 70 22 844 1,357

tylacetonate. 25 (lyclohexetmone phenylhydrazonc-i-Cu II acctyl- 0. 2 (0. 1) 70 2.2 711 1, 460

aeetona e. 26 Cyelohexanone phenylhydrazone-l-V III acetyl- 0. 2 (0.1) 70 22 858 1, 458

acetonate. Benzaldehyde phenylhydrazone 2 0 (1.0) 27 Benzaldehyde phenylhydrazone+0o III acctyl- 0 2 (0.1) 04 22 970 1, 513

acetonate. 28 Bcnzaldeltiyde pl1enylliydrazone+Mn II acetyl 0 2 (0.1) 94 22 062 1, 302

ace 01121 e. 29 Benz'ialdchyde phenylhydrazonc+Mn III acetyl- 0 2 (0.1) 94 2 1,038 1,388

cc onate. 30 Benzaldehydc phenylhydrazone-I-V III acetyl- 0. 2 (0.1) 04 22 1,172 1, 430

acetonate. Acetophenone phenylhydrazone 2. 0 (1. 0) 31 Acettiphcpone phenylhydrazonc+Ni II acetyl- 0. 2 (0.1) 71 22 769 1,431

ace ona e. 32 Acetophcgone phenylhydrazone+Co II acetyl- 0. 2 (0.1) 71 2. 905 1, 567

aeetona e. 33 Aeetotphenone phenylhydraz0ne+Mn II aeetyl- 0. 2 (0.1) 70. 5 22 906 1,410

ace onate. 34 Acctophenone phcnylhydrazone+Mn III acetyl- 0. 2 (0. 1) 70.5 22 825 1, 288

acetonatc.

Total gum The data in Table II show that in the presence of Feed: (mg/100 cc.) metal acetylacetonate-phenylhydrazone mixtures, total Heavy catalytic naphtha-kcyclohexaexistent gum ranged from 560 to 1,172 mg./ 100 cc. none about 2,400 and the potential gum formed ranged from 1,288 to 1,567 Heavy catalytic naphtha-l-cobalt acemg./100 cc. With the phenylhydrazones alone, existent tylacetonate about 2,600 gum ranged from 329 to 720 mg./10O cc. and potential Heavy catalytic naphtha+cyclohexagum ranged from 690 to 1.205 mg./cc. With the metal none-l-cobalt acetylacetonate about 9,000 chelates alone, existent gum varied from 236 to 798 hydrazones alone. Of greater importance is the rates of oxygen consumption. This variable is important because oxygen initates the free radical polymerization reactions which lead to gum formation. Under comparative conditions and using 1% cyclohexanone phyenylhydrazone plus 0.1% cobalt III acetylacetonate, roughly 300 cc. of molecular oxygen Was consumed or reacted with the olefinic constituents of light catalytic naphtha in 1 hour and a total of about 700 cc. of oxygen after about 3.5 hours. Using the hydrazone alone the comparable figures were about 280 cc. of oxygen after 1 hour=and about 450 cc. after 4 hours and for cobalt IH acetylacetone alone, about 80 cc. after 1 hour and about 425 cc. after 4 hours. As expected, the rate of oxidation with the mixed catalyst system was much greater than that observed with either the phenylhydrazone alone or the metal chelate alone. An induction period was observed with the metal chelate; initial oxygen consumption using the phenylhydrazone alone was rapid but it leveled oil? at about 300 cc. for about 2 hours which corresponds to hydroperoxide formation from cyclohexanone phenylhydrazone. The rate of oxidation with the catalyst mixture was so rapid in the initial stagesthat a rate couldnot EXAMPLE 3 The same regular catalytically cracked gasoline as used in Example 2 was employed in a series of runs where 500 cc. of the feed stock was employed per run except in this case only 0.5 gram of the hydrazone and 0.05 gram of the metal chelate was employed. In other words, the percentages were respectively 0.1% and 0.01% in Table HI, whereas, in Table II and in Example 2, the percentages were ten times as large, i.e., 1.0% and 0.1% respectively.

The .data in Table III show that, at these lower ca alyst concentrations, using benzaldehyde phenylhydrazone only produces 111 mg./ 100 cc. ofexistent gum and703 mg./ 100 cc. of potential gum. Total gum (existent+potential) was 814 mg./ 100 cc. Using the metal chelates alone, existent gum ranged from 108 to 303 mg./ 100 cc. and potential gum ranged from 751 to 816 mg./ 100 cc.

K mg./ 100 cc., and total gum ranged from 1,097 to 1,397

mg./ 100 cc. Obviously, total gum produced with the "mixed catalysts is greater than that observed with the phenylhydrazone alone or metal chelate alone. The effect of the mixed catalyst on the rate of oxidation (gum formation) using these catalyst levels was more pronounced even than when using the higher catalyst levels. Using the catalyst system, reaction conditions, and feedstock of Run 42, the total oxygen consumed or reacted amounted to about 50 cc. after 2 hours and about 210 cc. after 6 hours and 40 minutes, whereas, using the hydrazone alone, about 10 cc. of oxygen was taken up after 5 hours and about 30 cc. of oxygen Was consumed after 6 hours and 40 minutes. Where the oxidative polymerization was carried out using the manganese chelate alone, at no time was as much as 10 cc. of oxygen consumed up to 6 hours and 40 minutes. No induction period was observed with the manganese III acetyl-acetonate-benzaldehyde phenylhydrazone system. A 4 hour induction period was observed with the phenylhydrazone alone and no oxidation was observed with the manganese chelate until 16 hours had elapsed. Thus, at these catalyst levels, the mixed catalyst systems have a distinct practical advantage.

EXAMPLE 4 A number of runs were carried out in which 500 cc. of light catalytically cracked naphtha feed, which is the same feed stock used in Examples 2 and 3, was stored in metal cans for fourteen days and was shaken once each 24 hours. The oxidation reagents employed .are as shown in Table IV which lists a blank run involving the presence of no oxidative reagent and several runs in which only a phenylhydrazone was used or only a metal acetylacetonate was used. These runs are for comparison with Runs 51 through 59.

TABLE III.-LIGHT CATALYTIC NAPHTHA FEED (500 cc.)

Total gum (Mg/100 cc. of feed) Amount Time of Treat in grams contact, temp., Existent Potential Run Oxidatlve reagent (wt. percent) hrs. 0. (solid) (soluble) 24 25 6.6 302 35 O. (0. 1) 95 22 111 703 0. 05 (0. 01) 22 303 773 38 0. 05 (0. 01) 70 22 188 751 39 Mn III acetylacetonate 0. 05 (0. 01) 70 22 198 816 .Benzaldehyde phenylhydrazone 0. (0.1) 40 Benzgldelnyde phenylhydrazone-P00 II acetyl- 0. 05 (0. 01) 70 22 466 931 ace ona e. 41 Benzgldehyde phenylhydrazone+0u II acetyl- 0. 05 (0. 01) 71 22 260 837 ace n e. 42 Benzaldehyde phenylhydrazone+Mn III aeetyl- 0. 05 (0. 01) 71 22 383 897 acetonate.

TAB LE IV.-LI GHT CATALYTIC N APHTHA FEED (500 cc.)

[Stored in metal cans at 25 C. (or 14 days, shaken once each 24 hours] Total gum (mg/100 cc. of feed) Amount in grams (wt. Existent Potential Run Oxidativo reagent percent) (solid) (soluble) Blank 6.4 180 Benzaldehyde phenylhydrazone. 42.4 382 Acetophenone phenylhydrazone 9.4 414 Cyclohexanone phenylhydrazone. 3.8 411 Gyclopentanone phenylhydrazone.-. O. (0. 27. 342

48 Co II Acetylacetonate 0. (0. 01) 103 535 49 Cu II Acetylacetonate. 0. 05(0. 01) 68. 4 544 50 N1 II Acetylacetonate 0 05(0.01) 54.6 494 Benzaldehyde phenylhydrazone 0. 5(0. 1)

51 Benzaldehyde phenylhydrazone+Ni II 0 05(0.01) 46.8 450 acetylacetonate.

62 Benzaldehyde phenylhydrazone+Co II 0.05(0.01) 172.2 577 acetylacetonate.

63 Benzaldehyde phenylhydrazone+0u II 0.05(0.01) 102 517 acetylacetonate.

Acotophenone phenylhydrazone 0- 5(0. 1)

54 Acetophenone phenylhydrazone-i-Ni II 0.05(0.01) 62 2 1,546

acetylacetonate.

55 Acetophenone phenylhydrazone-i-Co II 0.05(0.01) 116 6 1,648

acetylacetonate.

56 Acetopheuone phenylhydrazono-i-Co III 0.05(0.01) 104.6 1,908

acetylacetonate.

57 Acetophenone phenylhydrazone+0u II 0.05(0.01) 79 4 1,346

acetylacetonate.

Cyclopenthanone phenylhydrazone 0. 5 (0. 1)

58 Oyclopontanone phenylhydrazone+0u II 0.05(0.01) 95.0 622 acetylacetonate.

69 Cyclopentanone phenylhydrazone+0o III 0.05(0.01) 106.6 509 acetylacetonate.

The data in Table IV show that total gum (existent +potential) using only the phenylhydrazones ranged from 369 to 424 mg./100 cc. Using the metal chelates only, total gum ranged from 529 to 638 mg./100 cc., while using the mixed catalyst systems, total gum ranged from 497 to 2,013 mg./ 100 cc. with the acetophenone phenylhydrazone-metal chelate mixtures being most effective. Using the mixed catalysts, all available oxygen in the system was consumed in 24 to 48 hours as determined by a Beckmann oxygen analyzer. Complete 0 consumption with the phenylhydrazones alone and metal chelates alone required to 14 days. Thus, the novel mixed catalysts may be effectively used in oxygen deficient systems in the absence of light. Under practical conditions, such systems could be added to stored distillates to remove gum forming unsaturates in the absence of a continuous supply of oxygen. The so streated distillates could then be purified by distillation prior to commercial use to remove soluble, as well as solid, polymers. Under these conditions, the rate of oxidation and polymer (gum) formation would again be of practical importance.

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 olefinically saturated acyclic hydrocarbon radicals, C C saturated cycloaliphatic radicals, aralkyl and aryl, R is selected from the group consisting of C C saturated acyclic hydrocarbon radicals, C C saturated cycloaliphatic hydrocarbon radicals, aralkyl, and hydrogen, including R and R being jointly a C C alkylene radical, the weight ratio of the hydrazone to metal chelate being between about 111 and about 10:1, and removing from the so treated distillate fuel at least the solid gum formed thereby.

2. A process as in claim 1 wherein the metal chelate is cobalt acetylacetonate.

3. A process as in claim 1 wherein the metal chelate is manganese acetylacetonate.

4. A process as in claim 1 wherein the metal chelate is copper acetylacetonate.

5. A process as in claim 1 wherein the petroleum distillate fuel is a catalytic cracked naphtha.

6. A process as a claim 5 wherein the metal chelate is a metal acetylacetonate.

7. Petroleum distillate fuels, originally containing olefins and molecular oxygen, containing at least one metal chelate of a metal having an atomic number between 23 and 29 inclusive and whose ligand portion is a dicarbonyl-containing compound having the formula:

. R unsaturated components and molecular oxygen wlth at least one metal chelate whose metal has an atomic numfi f ber between 23 and 29 inclusive and whose ligand portion 0 H 0 is a dicarbonyl-containing compound having the formula:

wherein R and R are selected from the group consisting R3 of hydrogen, hydroxyl, alkyl and alkoxy, each of the 6O alkyl-containing radicals having from 1 to 7 carbon atoms H per radical, phenoxy, phenyl, phenylalkyl, phenalkoxy,

wherein R and R are selected from the group consisting of hydrogen, hydroxyl, alkyl and alkoxy, each of the "alkylphenyl, and alkylphenoxy, and R is selected from the group consisting of hydrogen and lower alkyl, and containing at least one aryl hydrazone having the formula:

alkyl-containing radicals having from 1 to 7 carbon atoms R per radical, phenoxy, phenyl, phenylalkyl, phenalkoxy, alkylphenyl, and alkylphenoxy, and R is selected from I the group consisting of hydrogen and lower alkyl, and R 'Wi h t least one y hydrazone having the formula! 70 wherein R is selected from the group consisting of C -C R saturated acyclic hydrocarbon radicals, C -C saturated ary1 NH:NC/ cycloaliphatic radicals, aralkyl and aryl, R is select d R from the group consisting of C C saturated acyclic hydrocarbon radicals, C -C saturated cycloaliphatic hydrocarbon radicals, aralkyl, and hydrogen, and including R and R being jointly a C -C alkylene radical, the weight ratio of the hydrazone to metal chelate being be tween about 1:1 and about 10:1, said fuels having been freed of at least the solid gum formed following the addition of said chelate and said hydrazone.

8. Petroleum distillate fuels as in claim 7 wherein the fuel is a catalytic cracked naphtha.

9. Petroleum distillate fuels as in claim 8 wherein the metal chelate is a metal acetylacetonate.

References Cited UNITED STATES PATENTS 2,144,654 1/1939 Guthmann et al. 4468 OTHER REFERENCES The Chemistry of Hydrazine, Audrieth et al., Copyright 1951pp. 226-227.

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