US3574088A - Use of oxyalkylated phenylene diamines as heat exchange anti-foulants - Google Patents

Abstract

ADHESION OF DEPOSITS TO HEAT EXCHANGE METAL SURFACES IN PROCESSING HYDROCARBONS AT ELEVATED TEMPERATURES (I.E. FROM ABOUT 150*-1000*F. OR HIGHER) IS INHIBITED BY AN ANTI-FOULING AMOUNT OF AN OXYALKYLATED N-SUBSTITUTED PHENYLENE DIAMINE, AS EXEMPLIFIED BY OXYALKYLATED NPHENYL-P-PHENYLENE DIAMINE, OXYALKLATED N,N''-DIPHENYLP-PHENYLENE DIAMINE AND OXYALKYLATED N-CYCLOHEXY-N''PHENYL-P-PHENYLENE DIAMINE. OTHER ADDITIVES CAN ALSO BE EMPLOYED IN CONJUNCTION WITH THE ABOVE ANTI-FOULANTS.

Description

United States Patent 3,574,088 USE OF OXYALKYLATED PHENYLENE DIAMINES AS HEAT EXCHANGE ANTI-FOULANTS Lewis Bsharah and Walter R. May, St. Louis, Mo., assignors to Petrolite Corporation, Wilmington, Del.

No Drawing. Filed Aug. 25, 1969, Ser. No. 852,940 Int. Cl. Cg 9/16; 'C23f 11/00 US. Cl. 20848 10 Claims ABSTRACT 0E THE DISCLOSURE Adhesion of deposits to heat exchange metal surfaces in processing hydrocarbons at elevated temperatures (i.e. from about l50l000 F. or higher) is inhibited by an anti-fouling amount of an Oxyalkylated N-substituted phenylene diamine, as exemplified by Oxyalkylated N- phenyl-p-phenylene diamine, oxyalklated N,N'-diphenylp-phenylene diamine and Oxyalkylated N-cyclohexyl-N'- phenyl-p-phenylene diamine. Other additives can also be employed in conjunction with the above anti-foulants.

RELATED APPLICATION Application: Ser. No. 681,013

Applicants: Dudley Bruce Merrifield, Walter R. May,

Lewis Bsharah Filed: Nov. 6, 1967 For: Oxyalkylated Phenylene Diamines Assignee: Petrolite Corporation, a corporation of Delaware Status: Abandoned SUMMARY OF THE INVENTION This invention relates to a method of chemically treating hydrocarbon liquids which contact surfaces under high temperature conditions in order to inhibit, prevent and/or reduce the deposition of substances thereon. More specifically, this invention relates to the chemical treatment of the metal surfaces in contact with petroleum hydrocarbon liquids under conditions of high temperatures whereby said liquids tend to form deposits on such metal surfaces. This invention also relates to compositions employed in these processes.

In the processing of hydrocarbon liquids, particularly petroleum hydrocarbon liquids, elevated temperatures are often used in many necessary and important operations. To handle liquids at elevated temperatures, heat exchangers and the like devices are often employed to control the heat transfer rate from one operational step to another. When hydrocarbon liquids contact hot metal surfaces, there is sometimes a tendency for the liquid to decompose or undergo a chemical reaction that manifests itself in the form of deposits. These deposits may be either coke-like or they may be in the form of tenacious, soft, sticky sludges which adhere to hot surfaces. Adherences of deposits, rather than deposit-formation itself is the essence of the problem, in contrast to fuel storage where residue in the oil itself creates the problem.

The problem is well recognized in the art-note Petroleum Products Handbook, Guthrie (McGraw-Hill, 1960) pp. 1-13, U.S. Pat..2,908,824 and elsewhere.

These deposits tend to materially decrease the heat transfer capacities of the metal surfaces and hence increase operating expenses. These deposits also require additional efi'ort and time to remove and to restore the equipment to its original operating efficiency.

Petroleum refinery operations often encounter the above described conditions in many stages in the refining process. These deposits form on heat transfer surfaces at temperatures for example such as about ISO-225 F. and

ice

may be evidenced at temperatures as extreme as 1000 F. or higher.

It is practically impossible to prevent these deposits by coating the metal surfaces with a protective permanent coating due to the possible loss of heat transfer. In addition, the large volume of liquid that contacts such equipment increases the problem of treating metal surfaces in petroleum processing to prevent high temperature deposits.

It would be advantageous to add a chemical agent in extremely small amounts to a hydrocarbon liquid which 7 tends to form high temperature deposits whereby such deposits would be inhibited or prevented. It would also be desirable if such a chemical would not only prevent such deposits but would also remove them without necessitating the stoppage of a given operation. It therefore becomes an object of the present invention to prevent the formation of high temperature deposits on metal surfaces by chemical means.

Another object is to furnish a chemical which when added to a hydrocarbon liquid will prevent the depositforming tendencies of said liquid when it contacts metal surfaces at elevated temperatures.

A further object is to provide a chemical treatment which will prevent the formation of high temperature deposits by petroleum hydrocarbon liquids in contact with heat transfer equipment.

Yet another object is to furnish a chemical treatment capable of being combined with a thermally unstable, deposit-forming liquid whereby said liquid will not form deposits upon metal surfaces at elevated temperatures.

Still another object is to provide a chemical treatment which will remove high temperature deposits from metal surfaces of petroleum refining equipment without the necessity of stopping the operations of such equipment. Other objects will appear hereinafter.

We have now discovered a process of preventing, inhibiting and/or reducing the formation of surface deposits from petroleum hydrocarbon liquids during the processing thereof at elevated temperatures such as from about l501000 F. (i.e. the adhesion of deposits to heat exchange metal surfaces) by adding to the hydrocarbon liquid such as by solution and/ or dispersion an anti-fouling amount of an oxyalkylated N-substitued phenylene diamine, as exemplified by Oxyalkylated N-phenyl-pphenylene diamine, Oxyalkylated N,N-diphenyl-p-phenylene diamine and Oxyalkylated N-cyclohexyl-N'-phenyl-pphenylene diamine. Other additives can also be employed in conjunction with the above anti-foulants.

The anti-fouling additive system of this invention can be employed in refining crude petroleum as well as in the treatment of any component thereof which are exposed to high temperatures including the light distillates, for example light naphthas, intermediate naphthas, heavy naphthas, etc.; middle distillates, for example kerosene, gas, oil, etc; distillate lube oil stocks for example, white oil, saturating oil, light lube oil, medium lube oil, heavy lube oil, and the like.

In addition, the additive can be employed with other hydrocarbons such as xylene, benzene, purified hydro carbon compounds, etc. In addition, they can be employed under certain conditions with non-hydrocarbons, such as alcohols, phenols, etc. For example, they can be employed in a toluene extraction tower and stripper which process comprises mixing phenol and toluene in an extraction whereby phenol extracts impurities from toluene and the ratfinate is subsequently removed. Thereafter the mixture is sent to a stripper where the toluene is removed from the phenol by distillation. The remaining phenol is recycled to the extractor for further use. The system is operated over a wide temperature range, for example 23 0- 425 F. Deposits in the phenol circuit cause the loss of excessive amounts of phenol. It can be used in heat transfer units used in a furfurol extraction process, processing for example, intermediate distillates, paraflin distillates, decanted oil, vacuum cylinder stock, deasphalted cylinder stock, etc.

The amount of anti-fouling agent required in this invention is subject to wide variation but in general very effective results have been obtained by adding relatively minute amounts of the anti-fouling agent to the hydrocarbon liquid being processed, for example, amounts may be as low as 0.5 p.p.m. in hydrocarbon liquid, for example 1 to 500 p.p.m. or higher, for example 1000 or more p.p.m., preferably 1 to 100 p.p.m., with an optimum of 3-30 p.p.m. In general, the upper limit is determined by the economics of the process but other factors should be taken into consideration, such as whether large amounts will have any adverse effects on present or subsequent operations. Because of the many different types of operations Where hydrocarbons are heated to elevated temperatures under conditions where deposits are formed, it is difiicult to give specific ranges which will be effective in all operations. The amount of agent which inhibits the formation of deposits is referred to herein as an antifouling amount. The above figures relate to p.p.m. in terms of active anti-fouling chemical not including the solvent employed.

Inasmuch as the anti-fouling agent is employed in such small amounts and it is preferabl to feed them continuously or semi-continuously by means of a proportioning pump or other suitable device to the particular hydrocarbon liquid being processed or to add them in a similar manner to the apparatus in which the hydrocarbon liquid is being processed, it is desirable to incorporate the agent or a mixture of agents into a suitable solvent which will be compatible with the liquid which is to be processed. The solvent which is used to dissolve the active ingredient is also subject to some variation depending upon the solubility characteristics of the particular compound employed. In some cases, even though the active mixture is insoluble in a particular solvent, it will dissolve in a combination of solvents.

In the practice of the invention it is very desirable to start the treatment with the chemicals employed for the purpose of the invention at a higher dosage and then gradually reduce the dosage to the point Where fouling of the apparatus is just eliminated.

The invention is especially valuable where sour naphthas are being processed or where the oil being processed is a mixture containing some sour naphthas.

Examples of specific types of apparatus to which the chemical compositions of the invention can be added during petroleum processing are fractioning towers, stripping columns, debutanizers, depropanizers, deethanizers, heat exchangers, reboilers, hot product lines and other metal equipment (usually ferrous metal) which is brought into contact with the organic liquids being processed at relatively high temperatures. The invention makes it possible to extend the useful life of crude oil fractionating towers and other types of petroleum refinery equipment. It also makes it possible to provide cleaner inside surfaces resulting in better fractionation, better heat exchange in coolers, far less severe plugging and less time required for cleaning and maintenance.

The anti-foulants of this invention are oxyalkylated N- substituted phenylene-diamines as exemplified by oxyalkylated N-mono-substituted and N,N-disubstituted pphenylenediamines, i.e., p-phenylene diamines containing alkyl-, isoalkyl-, cycloalkyl-, aryletc., radicals in varying combinations attached to the nitrogen atoms. These include oxyalkylated p-phenylene diamines such as oxyalkylated N,N'-diphenyl-p-phenylene diamine, N-cyclohexyl-N'-phenyl-p-phenylene diamine, and N,N-di-secbutyl-p-phenylene diamine.

Other derivatives include for instance oxyalkylated N- isopropyl-N-phenyl-, N-isohexyl-N'-phenyl-, N-isooctyl- 4 N'-phenyl, N-phenyl-, N,N'-di-isopropyl, N,N'-diisobutyl, N,N'-di-isoctyl, and N,N'-dicyclohexyl pphenylene diamine.

These oxyalkylated phenylene diamines are prepared according to the methods disclosed in S.N. 681,013, filed Nov. 6, 1967, now abandoned, which is by reference incorporated into this application as part hereof.

Oxyalklated of the phenylene diamines is effected by employing suitable alkylene oxides or equivalent compounds.

The term alkylene oxide, as used herein means a compound containing the following 1,2-epoxy group, also called an oxirane group, vi.e.

and wherein each unsatisfied epoxy carbon valence of said group is satisfied for example by hydrogen, a hydrocarbon radical, a substituted group for example an ether-containing group, a halogen-containing group, or other radicals which do not interfere with the polymerization process. In addition, the unsatisfied epoxy carbon valences collectively can represent a divalent aliphatic hydrocarbon radical which together with the epoxy carbon atoms form a ring containing, for example, from 5 to 10 carbon atoms inclusive. It is to be understood, also, that the term lower alkylene oxides designates that each unsatisfied epoxy carbon valence of the above-depicted structural unit can be satisfied by hydrogen, a lower alkyl, e.g. methyl, ethyl, propyl, etc., substituted derivatives thereof, and the like.

For example, the monomeric alkylene oxides employed are vicinal-epoxyhydrocarbons which have a single vicinal epoxy group which can be characterized by the following formula:

wherein R R and R are hydrogen, a hydrocarbon radical, a haloalkkyl or aryl radical, an ether-containing radical or other types that do not interfere with the polymerization procedures such as certain nitrogen-containing derivatives sulfur-containing groups, ester groups, etc. Where R R and R are hydrogen, the oxide is ethylene oxide.

Representative alkylene oxide monomers which can be employed are those in which R and R are hydrogen and R is an organic radical such as alkyl, aryl, halogen-containing a l-kyl or'aryl, ether-containing alkyl or aryl, unsaturated alkyl, ester-containing alkyl or aryl or mixtures of these types. Specific examples are ethylene oxide (where R is also hydrogen), 1,2-pentene oxide, 1,2-hexene oxide, 1,2-octene oxide, 1,2-decene oxide, 1,2-dodecene oxide, propylene oxide, 1,2-butylene oxide, higher 1,2-epoxy alkanes, styrene oxide, 0, m, or p-alkyl-styrene oxide, epihalohydrins such as epichlorohydrin, epibromohydrin, epifluorohydrin, 1,1,l-trifiuoro-2-propylene oxide, chlorostyrene oxide, methyl glycidyl ether, ethyl glycidyl ether, isopropyl glycidyl ether, methyl glycidyl ether of propylene glycol, methyl glycidyl ether of dipropylene glycol, methyl glycidyl ether of tripropylene glycol, hexyl glycidyl ether, b-chloroethyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether o-, m-, and p-chlorophenyl glycidyl ether, o-, m-, and p-methylphenyl glycidyl ether, butadiene monoxide, chloroprene monoxide, allyl glycidyl ether, glycidyl methacrylate, glycidyl pivalate, trimethylsilyl glycidyl ether, butyl glycidyl formal, diethylglycidyl amine, N-(2,3-epoxypropyl) morpholine, N,N-dimethyl aminoethyl glycidyl ether, etc.

Other representative epoxides which can be used are those in which R is hydrogen and both R and R are organic radicals generally defined as above for R Specific examples are, isobutylene oxide, oz-methyl styrene oxide, 1,1-diphenylethylene oxide, 1 ,l ,1-trifiuoro-2-methyl-2 propylene oxide, methyl methacrylate oxide, methylene cyclohexane oxide, etc.

Other representative epoxides which can be employed are those in which R is hydrogen and R and R are organic radicals generally defined as above. Specific examples are cisand trans- Z-butene oxide, 1,1,1-trifiuoro-2- butene oxide, cyclohexene oxide, vinyl cyclohexene oxide, etc.

Trisubstituted ethylene oxides can also be employed in which R and R and R are all organic radicals as defined above. Trimethyl ethylene oxide is illustrative of this type. Furthermore tetrasubstituted ethylene oxides may be employed such as tetramethyl ethylene oxide.

The oxyalkylation may be carried out with one alkylene oxide, such as for example ethylene oxide, etc., so as to yield a homo-oxyalkylate; a mixture of alkylene oxides, such as for example a mixture of ethylene and propylene oxides, so as to yield a hetero-oxylkylate; al

marized in Table I. Example 6 is carried out without catalyst or solvent wherein epichlorohydrin acts both as reactant and solvent.

EXAMPLE 4 TABLE I.OXYALKYLATED N-SUBSTITUTED p-IHENYLENEDIAMINES Catalyst Mole percent Alkylcne oxides Mole of based on Ex. R R diamine Name diamine Solvent Name Mole Comments 1 phenyl H 0.10 BFa'oEtg 2 Dimethyl ECH 2 0.1

formamide. phenyl H 0.10 BFyOEt-z 2 do ECH 2 0.2

phenyl H 0.15 BF -OEtz 2 .d0.. EtO 3 0.65 4.1 moles EtO per mole of diamine consumed.

4 phenyl cyelohexyl 0. 15 BFa-OEtz 2 do EtO 3 0.30 2 moles EtO per mole of diamine consumed.

5 phenyl cyclohexyl 0.10 BFg-OEtz 0.10

6 phenyl eyclohexyl 1. 4. 0 Reflux hrs., remove excess ECH, 2 moles consumed. 7 phenyl cyelohexyl 1 BFg-OEW Dimethyl EtO 5. 95 Moles consumed.

ionnamide. cyclohexyl 1 BFs-OE122 Et0 14.01 Do. eyclohexyl 1 BF -OEtz P10 1. 99 Do. cyclohexyl 1 BFa-OEtz PrO 11. 85 Do. H 1 BFa-OEtz EtO 5. 00 Do.

1 Unsubstituted phenylene diamine, i.e. phenylene diamines.

2 E CH= Epichlorohydrin.

3 EtO=Ethylene oxide.

NH2-NHz can also be similarly oxyalkylated to yield oxyalkylated 4 Sufiieient BF -OEt2 was employed to initiate the oxyalkylation and NaOH was then added to complete it.

* Pr0=Propylene oxide.

ternate additions of different oxides, such as first ethylene then propylene oxide, so as to yield a block oxylkylate. In addition, one or more of the block oxyalkylate units may be hetero, etc.

The phenylenediamine may be oxyalkylated 01 at least one or more of the nitrogen-bonded hydrogens, up to all available N-bonded hydrogens. In certain instances it may be difficult to oxyalkylate all N-bonded hydrogens. The phenylene diamine may contain 1 or more moles of oxyalkylate per molecule, such as one mole for each available nitrogen hydrogen.

In addition, the oxylkylate may contain more than one mole of oxyalkylate per molecule such as for example 1-5, 1-10 moles or more. Where desirable more than 10 moles or more can be employed, such as -100 or more moles.

Thus, the phenylenediamine may be represented by where R is a nitrogen-bonded radical, preferably a hydrocarbon, 0A is a moiety of the alkylene oxide, n is the number of oxyalkyl groups, and m is a number determined by the number of active N-hydrogens on the phenylene diamine, such as for Examples 1-3.

Those nitrogen-bonded groups on the phenylene diamine groups which are not substituted with R or (0A).,H are hydrogen. a

The following examples are presented for purposes of illustration and not of limitation. Since all of the examples described in the table were prepared in the manner of Example 4, to save repetitive details, they are sum- The phenylene diamines are also oxyalkylated under similar conditions with butylene oxide. They are also oxyalkylated with mixtures of alkylene oxides to yield a heterooxyalkylate such as mixed ethylene-propylene oxides; alternately with one alkylene oxide and then with another oxide to yield block oxyalkylates such as a block of ethylene oxide, then a second block of another oxide such as propylene oxide, etc.

The oxyalkylate is also carried out by taking the oxyalkylate produced with the Lewis acid, as in the above table, and continuing oxyalkylation with an anionic catalyst such as with a basic catalyst (e.g. NaOH, KOH, etc.). This was done in Examples 71l.

In addition to the anti-foulant, other auxiliary additives may also be employed to enhance the anti-foulant function of the anti-foulant.

One auxiliary additive is a copoylymer derived from an acrylic ester of the formula and N-vinyl-2-pyrrolidone, for example a coplymer containing the following units:

having a molecular weight for example of at least 50,000,

7 for example 50,000500,000, or highr, but preferably l00,000400,000 with an optimum of 300,000400,000 of which vinyl pyrrolidone comprises at least 1% by weight of the copolymer, for example 130%, but preferably 3-15% with an optimum of 5l0%; where Y is of N-vinyl pyrrolidone. In making this ester type resin by polymerization 0.075 part, by weight of the monomer mixture, of benzoyl peroxide is added to said mixture, and the so-formed mixture is stirred and 'warmed to dissolve the benzoyl peroxide. Then, 20 parts, by Weight of said hydrogen, a lower alkyl group such as methyl, ethyl, etc., 5 mixture, of a white mineral oil is added to a reaction Z is an hydrocarbon group having, for example, 1-30 carvessel which is swept out with nitrogen gas, and the sobon atoms, but preferably 8-18 carbon atoms. These formed mixture is slowly added to said white mineral polymers are preferably acrylic or methacrylic polymers oil in said reaction vessel over a two hour period. At 2.6 or polymers derived from both in conjunction with vinyl 10 hours, 0.015 part, by weight of said monomer mixture, of pyrrolidone. The Z group on the polymer, which can be benzoyl peroxide is added to the vessel. Then, at 4, 4.6, the same throughout or mixed, can be octyl, nonyl, decyl, 5.3 and 6 hours, respectively, further additions of 0.022 undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, octapart, by weight of said monomer mixture, are made and decyl, etc. Lower alkyl groups can also be employed such during this time and until 9-10 hours, when heating is as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, etc., discontinued, temperatures are maintained between 97 C. but they preferably are employed as copolymers of the and 103 C. At 6.5 hours, 28 parts of white mineral oil higher Z groups, for example a copolymer of dodecyl are added, and the batch is stripped of volatile products methacrylate and methyl acrylate, etc. The acrylic ester by being h ated up to 145 C. at 2 mm. pressure, giving units may be derived from one or more acrylic type mona yield of about 90% of cooplymer having an average omers and may be fully acrylic or fully methacrylic or 1110166111211" g of 450,000- both acrylic and methacrylic. The polymer may be ran- Another auxiliary additives is a metal deactivator, for dom, block graft, etc. example, those conveniently employed in deactivating cop- Also, Z may also be an alkylated aromatic group Such per, 1ron and other metals from hydrocarbon systems. as butyl phenyl, amyl phenyl, etc., or a cycloaliphatic Typlcal examples are thosF de sclrbed group such as cyclohexyl. Thus, non-limiting specific ex- .2 of course P Sklued the art 15 aware that amples of suitable monomeric esters are: methyl acrylate, many other meta1 deactwators are known and can be ethyl acrylate, propyl methacrylate, amyl acrylate, lauryl ployfid heremacrylate, lauryl methacrylate, cetyl methacrylate, octa- The compounds metal deactlvators are decyl methacrylate, amylphenyl methacrylate, cyclohexyl preferably of the type of Schlfi S bases and may repre methacrylate, etc., including the analogous acylate 0f sented by the formulae methacrylate esters. Copolymers of the above and other (1) ACH=NRN=CHB acrylic esters may be used, for example, a copolymer of methyl or ethyl acrylate and dodecyl methacrylate in and Prefelably conjunction with vinyl pyrrolidone. However, it should be understood that this description does not preclude the h A d B h presence of small amounts of unesterified groups being W erem an eac represimts an orgamc radlcal and present in the Polymer Le approximately 5% or less of preferably a hydrocanbon radical. In Formula (IQA and where B each preferably represents a hydrocarbon radical. In It should be understood, of course, that when the above ii (DA and fi fi i i. i g g' compounds are polymerized, the polymerization should ma cu gor f i ma 6 e e-rocyc 1c i' 16 e not be carried to such an extent as to form polymers hydroxyl radlcal 1S fl dlrecfly to a nng carbop which are insoluble or non-dispersible in the petroleum atom} Orth? to g p, R represents an allhydrocarbon used. The polymerization may be carried phatic radical havmg the two N atoms attached Fhrectly out by methods known to the art, such as by heating mildly to dlfferent carbon aioms the Same open The preferred metal deactivator 1s that former from sal1cylal 1n the presence of a small amount of benzoyl peroxide, d6hyde and 1 3 propylenediamine 23: ig ggg f g g fg $2225 gg gggg i g Typical examples of aldehyde and 'polyamines employed mer's See Frenchppat 1 163 y py p y in preparing these Schiff bases include the following:

The following are some illustrative examples of vinyl Aldehydes pyrrolidone-acrylic ester type resins which can be em- Benzaldehyde ployed in this invention. 2-methylbenzaldehyde TABLE A.VINYL PYRROLIDONE-AORYLIO ESTER-TYPE RESINS Vinyl pyrrolidone, M01 Avg.- percent ratio mol. Monomer 1 Monomer 2 Monomer 3 by Weight 1:2:3 Weight Example:

1(a) Tridecyl Octadeeyl 7.5 1:1 300,000

methacrylate. methacrylate; 2(a) Dodecyl 10 500,000

methacrylate. --d0-... Butyl acrylate. 15 2:1 400,000 Octadecyl 5 450, 000

methacrylate. 5(a) Tridecyl 20 350,000

methacrylate. 6(a) Octadeeyl ethyl 10 3:1 500,000

methacrylate. methacrylate. 7(a) Dodecyl Ethyl acrylate 5 4:1 400,000

methacrylate. 8(a) Cetyl Octadecyl Butyl 7.5 2:1:0.5 850,000

methacrylate. methacrylate. methacrylate.

3-methylbenzaldehyde 4-methylbenzaldehyde Z-methoxybenzaldehyde 4-methoxybenzaldehyde a-Na-phthaldehyde b-Naphthaldehyde 4-phenylbenzaldehyde Propionaldehyde Polyamines Ethylenediamine l-2-propylenediamine 1-3-propylenediamine l-fi-hexamethylenediamine 1-IO-decamethylenediamine Diethylenetriamine Triethylenetetramine Pentaerythrityltetramine 1-2-diamino-cyclohexane Di (b-aminoethyl) ether Di-(b-aminoethyl) sulfide Where auxiliary additives are employed, the ratio of these additives to the anti-foulant can also vary 'widely. In general the weight ratio of anti-foulant to the acrylictype polymer is at least 1:1, from about 1:1 to 100:1 such as about 2:1 to 50:1, for example, from about 3:1 to 20:1 but preferably from about 5:1 to 15:1.

In general, the ratio of anti-foulant to metal deactivators is at least about 1:1, from about 1:1 to 100:1 such as about 2:1 to 50:1, for example from about 3:1 to 20:1 but preferably about 5:1 to 15:1.

The following examples are presented for purposes of illustration and not of limitation.

The tests were carried out according to the following procedure:

TEST PROCEDURES The apparatus for the test measurements makes use of a heat exchanger and the loss of heat transfer is used as a criteria for evaluating the fouling rate. The method utilizes a controlled temperature test chamber containing a single A3 stainless steel tube heat exchanger. Crude oil is fed through this tube and the degree of fouling is measured and recorded continuously by a change in the temperature differential of the inlet and outlet temperature of the test section. By controlling the temperature, pressure and flow rates, the fouling characteristics of both crude oil and refinery charge stocks, with and without anti-foulant compounds can be readily determined under conditions approaching those of an operating refinery.

In these tests, the anti-foulant, when used, is blended with the desalted crude oil in a reservoir held at room temperature. This desalted crude is pumped by means of a high pressure pump into the furnace where the crude oil enters and passes through a heat exchanger. The temperature is measured at the entrance and exit points of the heat exchanger and the difference between these two temperatures (AT) is continuously recorded. In tests where little or no fouling occurs in the heat exchanger the change in this temperature difference remains fairly constant or zero with time. As fouling occurs this temperature differential will change with time, increasing in value as fouling occurs. A test run normally lasts 46 hours. A clean A" OD. preheat section and a new heat exchanger section are used for each run.

Test data are presented in the following tables.

TABLE II [Crude oil; test temperature 500 F.; pressure 500 p.s.i.]

Coneen- Fouling tratlon, rate, Oil stock Anti-foulant used p.p.m. F./hr.

Midwest Desalted Crude Oil A 0, 50 Do Commerclal 20 0, 22

anti-foulant A. Do Commercial 10 0. 27

anti-foulant B. Do Commercial 20 0.20

anti-ioulant C. Do Commercial 10 0. 49

antifoulant D. Do Commercial 20 0. 21

anti ioulant E. Commercial 10 0.42

anti-foulant F. D0 .1 Commercial 10 0.15

anti-ioulant G. Do Commercial 10 0.16

anti-foulant H. Do Commercial 5 0, 26

anti-ioulant I. Do Example 11 5 0. 13 Midwest Desalted Crude Oil B 0. Do Commercial 30 0. O4

anti-foulant G. Do Example 11 I- 15 0. 08 Midwest Desalted Crude Oil C- 0. 48 Do Commercial 10 0.24

anti-foulant Q Do Vinyl pyrrolidlne- 10 0.43

acrylic ester-type resin, Ex. 9(a). Do -50 mixture of Ex. 11 10 0. 13

and a vinyl pyrrolidineacrylic ester-type resin, Ex. 9(a). Midwest Desalted Crude Oil D 0.37 Do Example 11 15 0. 16 Commercial 30 0.16

anti-foulant G. Do -[Commereial 30 0. 34

antidoulant B. Do [Commercial 30 0. 34

anti-foulant G.

TABLE III [H DS charge stocks; test temperature 500 F.; presure 500 p.s.i.l

Conccn- Fouling tration, rate, Oil stock Chemical used p.p.m. F./hr.

Hydrodcsulionatcd Charge Stock E 1. 49 Do Commercial 30 0. 90

anti-foulant G. Do Commercial 30 0. 77

anti-ioulant H. Do Example 11 30 0.50

TABLE IV [Heavy wax crudes; test temperature 500 F.; presssure 500 p.s.i.]

Concen- Fouling tratlon, rate, Oil stock Chemical used p.p.m. F./hr.

Heavy Wax Crude Charge 0.88 Do Example 11 0.74 0. 31 Do 50-50 mixture of Ex. 11 1O 0. 13

and a vinyl pyrrolidineacrylic ester-type resin, Ex. 9(a).

Although the invention has been described with reference to preferred embodiments thereof, it is understood that the description is by Way of illustration only. Accordingly it is contemplated that modifications and variations can be made by those skilled in the art in light of my description without departing from the spirit of the invention.

Having thus described our invention What We claim as new and desire to obtain by Letters Patent is:

1. A process of inhibiting in hydrocarbon refinery operations at elevated temperatures the adhesion of deposits on heat transfer surfaces of a heat exchanger which comprises incorporating into the hydrocarbon prior to contact with the heat exchanger an anti-foulant amount of an oxyalkylated N-substituted phenylene diamine.

2. The process of claim 1 Where the phenylene diamine prior to oxyalkylation has the formula 5. The process of claim 4 where the oxyalkylated N- substituted phenylene diamine has the formula References Cited UNITED STATES PATENTS I 3,017,343 1/1962 Pollitzer 20847 3,328,284 6/1967 Godar 20848 3,328,285 6/1967 Godar 20848 where R is phenyl and R is either H or cyclohexyl.

3. The process of claim 2 where R is hydrogen.

4. The process of claim 3 Where the oxyalkylated N- substituted phenylene diamine has the formula U.S. c1. X.R. 252-68, 403