US2120244A - Treatment of motor fuel - Google Patents

Description

Patented June 14, 1938 Charles G. Dryer, Chicago, 111., ass'ignor to Universal Oil Products ComparmOhicago, 111., a corporation oi'Delaware Serial No. 38,793

No Drawing. Application August 31,1935,

16 Claims.

. This invention relates to the treatment of.

hydrocarbon motor fuels produced as the main product in petroleum cracking operations, though the process may also be applied to analogous frac- 5 tions of similar boiling range produced in' the distillation of other types of hvdrocarbonaceous 'materials or to various motor fuel blends comprising stocks from different sources. p More specifically, the invention is concerned I with a method of treatment which results in the,

stabilization of various types of gasolines which have a tendency to deteriorate on storage with loss in such valuable properties as light color,

low gum content and antiknock value, the de-. teriora'tion being dueprincipally to the action of oxygen and being accelerated by. the photochemicalefiects of sunlight.

.- As a rule, little trouble is experienced in loss I of the above mentioned properties during the. storage of straight run gasolines, since there are substantially no oleflns in the lower boiling fractions of crude oils, though tests indicate that higher molecular weight oleflns may be present in the higher boiling fractions. The cracking process, however, which is employed to produce additional yields of gasoline from gas oils and petroleum residua invariably produces definite yields of unsaturated aliphatic hydrocarbons which have varying degrees of stability depending upon the type or \msaturation which character- 'izes them. The mono olefins are essentially stable even in direct contact withair and sunlight.

Conjugated dioleflns, however, such as butadiene and its derivatives, which are present in cracked gasolines produced under intensive crackingconditions, have been shown to be the compounds which firstadd oxygen to produce derivatives of a peroxidic character which in turn act autocatalytically to cause further oxygen addition with 40 the development of gummy materials, compounds causing color and haze and ultimately definite amoimts ot acids, aldebydes, ketones and other o y en-containing compounds.

The art of using inhibitors to retard the re- 7 -actions of deterioration occurring-in unstable gasoline has been developed to a considerable extent, and has largely overcome the disadvan-.-

tages inherent in the chemical treatments aimed at stabilization, which entailed both-loss of maso terlal and loss in antilrnock rating. Use has been madeoi a, wide variety or materials including both-pureicompounds and mixtures, and apparently the materials represent a large number of diilsrent'chemicsl classes. They all. however,

have omnmon characteristic,- which is that (or sil -9) tuted para aminophenols and Monoalkylp-aluinophenols Diaikylphenylone diamines" they either preferentially absorb oxygen and prevent the initial formation of oleilnic peroxides or that they decompose the peroxides initially formed so that the reactions of deterioration are halted for a period of time depending upon the 5 amount and potency of the inhibitor. The pres-.

ent invention is a contribution to the inhibitor art and consists in the use of a particularly eilicient class of blended materials as inhibitors in unstable'hydrocarbon mixtures, particularly motor fuels.

' In one specific embodiment, the present inven-. tion comprises the'treatment of unstable cracked gasolines to preserve their valuable properties in respect to gum content, color and an'tiknock 15 value with alcoholic "solutions of alkyl-substi-f alkyl-substituted paraphenylenediamines.

- 'An extensive series on investigations has indicated that solutions 01' the above character are 20 particularly efficient in inhibiting the deteriora-e tion of cracked gasolines andfthat they -.are furthermore readily dispersed and dissolved when added in the relatively small quantities which have been found to be necessary for the proper 25 protection of gasoline. The invention is therefore a definite contribution to the inhibitor art irom two very practical standpoints, (1) that of furnishing inhibitors of high potency, and (2) that of furnishing a liquid material which is readily handled and quickly dissolved.

The general formulas of the two classes-of compounds which are dissolved in alcohol in varying proportions to form the present type of inhibitors are given below, in which R. represents 'alkyl-substituting groups and the other letters have their usual chemical significance.

R-N-H R-NI i B may represent methyl, ethyl,'propyl, butyl, -amyl, hexyl and-other higher molecular weight aliphatic residues, andin'cludes" the isomeric forms; For example, mixtures 01' monomethyl 5 p-aminophenol and dimethyl p-phenylenediamine may be dissolved-in a suitable alcohol or mixtures may be madeoi" compounds in which the substituting. groups. are diil erent .orabsent in one oi the compounds. .An example oi mixed 'isoamyl p-am inophenol and either p-phenylenediamine di-isoamyl p-phenylenediamine. Obviously, by' varying the character of the alkyl-' substituting groups in the main classes of compounds and also the proportions thereof, a large number of alternative combinations are possible, which, however, will not have exactly the same inhibiting efliciency in a given unstable gasoline or the 'same comparative efllciency in different gasoline, so that various combinations are not exact equivalents. Furthermore, different compounds which are proposed as inhibitors will have different solubilities in different alcohols and blends thereof so that the amount of solvent necessary for making a sufficiently fluid inhibitor and assisting its dispersion throughout a large body of gasoline will also vary. Also either or both of the classes of compounds referred to may be treated in accordance with the invention.

It is particularly to be noted-that all of the members of the two classes of substituted compounds whose single or joint use is proposed as inhibitors are solids at ordinary temperatures and a as such are difiicult to handle and difficult to dissolve in gasolines requiring inhibitors. The discovery that these compounds which have high inhibiting potency when properly dispersed through a body of gasoline could be easily handied and quickly dissolved when utilized in alco- .holic solution is one of the notable contributions to the inhibitor art which characterizes the present invention. The various alcohols which may be used, which comprise usually the lower inc-- lecular weight aliphatic alcohols, have difierent cates also'whether a gasoline to which the solution was added in the concentration of 0.004% remained perfectly clear or precipitated out a small quantity of insoluble material. Incidentally thetable also shows the corresponding induction periods of the gasoline to which the inhibitors were added, this figure indicating the time to measurable oxygen absorption in the standard bomb test:

Solvent action of alcohols I l t t C dlti i' ti so van on on 0 on solvent 1 part of gasoline period,

solid minutes Methyl alcohol, absolute. 1 Cloudy 325 Do 2 Slightly cloudy 325 Do 5 Cloudy 330 Ethyl alcohol, absolute. 1 Clean... 345 Do 2 do. 350 5 ldo 355 1 .do. 335 2 do.- 350 5 do 360 1 d0 340 2 do 330 5 ---do 345 The above table indicates that generally in the case of the solid combination employed, the solvent action of the aliphatic alcohols increased with increasing molecular weight, though the induction period did not vary to any great extent.

When the gasoline was cloudy or hazy after the addition of the inhibitor blend, .it eventually separated some slight precipitate.

, The following table is introduced to show fur ther results when using diflerent alcohols as solvents and when employing the same inhibiting materials in concentrations of 0.025% by weight of an unstable gasoline, which is anentirely V practical percentage from the standpoint of cost, clarity of gasoline, color, drop, etc. One part by weight of the same mixture used when obtaining figures in the preceding table was dissolved in three parts by weight of the alcohol shown.

Eflect of solvents on induction per od In the following specific example which is introduced to show a very practical application of the present type of inhibitor to the treatment of an unstable gasoline, a blend of alcohols was used which apparently has a particularly good solvent action on the isoamyl derivatives mentioned as well as on other combinations of other compounds. The example is introduced to show the practical character of the process but is not intended to unduly limit the scope of the invention.

The blend of alcohols used consisted of 20% by volume of isobutyl alcohol with 80% by volume -of absolute methyl alcohol. This blend dissolved an equal part by weight of a mixture which was substantially 80% mono iso amyl p-aminophenol and 20% di-iso amyl p-phenylenediamine. solution was perfectly clear and could be added Theto test gasolines in amounts up to 0.1%. without methyl alcohol is considerably cheaper than theiso butyl alcohol.

The foregoing specification disclosing the character of the invention will enable those skilled in the art to which it pertains to approach its commercial value and the data introduced will show the type of results obtainable in practice, though neither section is intended to be unduly limiting.

I claim as my invention: 1 l. A method for stabilizing cracked gasolin against deterioration which comprises adding to the gasoline an alkyl-substituted para-aminophenol and an alkyl-substituted paraphenylenediamine dissolved in an alcoholic solvent comprising a butyl alcohol.

2; A method for stabilizing cracked gasoline 'against deterioration which comprises adding to the gasoline an alkyl-substituted para-aminophenol and an alkyl-substituted paraphenyl- 'enediamine dissolved in an alcoholic solvent comsolved in an alcoholic solvent comprising isobutyl alcohol.

6. An inhibitor for cracked gasoline comprising a mixture of methyl and isobutyl alcohols having dissolved therein an alkyl-substituted paraaminophenol and an alkyl-substituted para- 1' phenylenediamine.

'7. A method for stabilizing cracked gasoline against deterioration which comprises adding to the gasoline a relatively small amount of a solution of an alkyl-substitutedpara-aminophenol and an alkyl-substituted paraphenylenediamine, the first-named compound being in substantially greater proportion than the second,. and the solvent of said solution comprising a major proportion of methyl alcohol and a minor proportion of an aliphatic alcohol having from 2 to 4 carbon atoms.

8. A method for stabilizing cracked gasoline against deterioration-which comprises adding to the gasoline a relatively small amount of a solution of mono-iso-amyl para-aminophenol and di-iso-amyl paraphenylenediamine, the firstnamed compound being in substantially greater proportion than the second, and the solvent of said solution comprising a major proportion of methyl alcohol and a minor proportion of an,

aliphatic alcohol having from 2 to 4. carbonatoms.

9. A method for stabilizing cracked gasoline the first-named compound being in substantially greater-proportion than the second, and thesolvent of said solution comprising a major pro portion of methyl alcohol. and a minor proportion of abutyl alcohol. v

- "10..A method for stabilizing'cracked gasoline against deterioration which comprises adding to the gasoline a relatively small amount of a solution of mono-iso-amyl para-a'minophenol and diiso-amyl paraphenylenediamine, the first-named compound being in substantially greater propor tion than the second, and the solvent of said solu-.

tion comprising a major proportion of methyl alcohol and a minor proportion of a butyl alcohol.

11. An inhibitor for cracked gasoline comprising a solution of an alkyl-substituted para-amino phenol and an alkyl-substituted paraphenylenediamine, the first-named compound being in substantially greater proportion than the second, and the solvent of said solution comprising a major proportion of methyl alcohol and a minor proportion of an aliphatic alcohol having from 2 to 4 carbon atoms.

12. An inhibitorfor cracked gasoline comprising a solution of mono-iso-amyl para-aminophenol and di-iso-amyl paraphenylenediamine.

the first-named compound being in substantially greater proportion than the second; and the solvent of said solution comprising a major proportion of methyl alcohol and a minor proportion of an aliphatic alcohol having from 2 to 4 carbon atoms.

13. Aninhibitor for cracked gasoline compris ing a solution of an alkyl-substituted para-aminophenol and an alkyl-substituted paraphenylenediamine, the ilrst-named compound being in substantially greater proportion than the second, i

and the solvent of said solution comprising a major proportion of methyl alcohol and a minor proportion of a butyl alcohol.

14. An inhibitor for cracked gasoline compris ing a solution of mono-iso-amyl para-aminophenol and di-iso-amyl paraphenylenediamine, the first-named compound being in substantially greater proportion than the second, and the solvent of said solution comprising a major proportion of methyl alcohol and a minor proportion of a butyl alcohol.

, 15. A method for stabilizing cracked gasoline against deterioration which comprises'adding to the gasoline a relatively small amount of a solution of an alkyl-substituted para-aminophenol and an alkyl-substituted paraphenylenediamine, the first-named compound being in substantially greater proportion than the second, and the solvent of said solution comprising a major proportion of a mixture of methyl alcohol and an aliphatic alcohol having from 2 to 4 carbon atoms.

1 16. An inhibitor i'orcracked gasoline comprising a solution of an alhvl-substituted para-amjor proportion of a mixture of methylalcohol. and an aliphatic alcohol having from 2 to 4 carbon atoms.

CHARLES G. DRYER.