US2334378A - Hydrocarbon treatment - Google Patents

Description

Patented Nov. 16, 1943 HYDRO CARBON TREATMENT Carl William Berger, McPherson, Kans assignor I to Globe Oil & Refining Company, Lemont, 111., a corporation of Illinois N Drawing. Application June 8, 1940, Serial No. 339,497

13 Claims.

The present invention relates to a process of refining hydrocarbons and more particularly to an improved process for improving the specifications of cracked petroleum hydrocarbons, particularly those having boiling ranges between 300 7 F. and 600 R, such as cracked kerosene, cracked naphtha, cracked distillate thereof.

As early as 1914, it was proposed to refine hydrocarbons by strongly heating the same at temperatures of about 300 C. or more, under pressures sufficient to maintain the hydrocarbon in the liquid state, with various acids of phosphorus, particularly orthophosphoric acid, In recent years numerous modifications of this general type of procedure have been proposed, but as far as I am aware, all such prior processes have involved energetic treatment of the hydrocarbons at temperatures varying from at least 130 C. to over 300 0., these elevated temperatures .having heretofore been regarded as essential, apparently for the reason that the active acid of phosphorus in the refining operation was considered to be the molecularly dehydrated acids of phosphorus, such as the meta and .pyro phosphoric acids, which are produced only at such high temperatures. Because of the elevated tem peratures employed in the prior refining processes involving the use of acids of phosphorus, vigorous reactions take place between'the hydrocarbon and the acid, which reactions are similar to those occurring in the sulfuric acid treatment of cracked hydrocarbons. These reactions involve esterification, polymerization, condensation or the formation of addition or reaction products with the acids. The by-products are of such a nature andare formed in such amounts in prior processes that it is necessary to remove them from solution or suspension in'the treated oil by resort to fractional redistillation, absorption on porous surfaces, or by various other refining operations, all of which increase the cost of manufacture. These refining operations are necessary, in prior processes, firstly, because it is necessary to remove the high boiling polymerized and condensed reaction products resulting from such energetic treatment in order to obtain a final product of the same boiling range as the untreated distillate; and secondly, because satisfactory color improvement is not attained by such prior art processes unless the acid treatment is followed by redistillation or by further refining operations.

The principal object of the present invention is to provide an improved method of refining or fractional cuts cracked hydrocarbons, which obviates the disadvantages of the prior art phosphoric acid processes.

4 Another object of the invention is to provide a simple and economical process for refining cracked distillates, which produces directly, without the necessity of fractionally redistilling the treated material, a product of greatly improved specifications with respect to gum content, color, odor, and sulfur content, and of the same distillation range as the untreated distillate.

- Another object of the invention is to provide a process for the improvement of cracked distillates, by which process the cracked distillates are rendered substantially less susceptible to deterioration, particularly when held even for short periods of time, in contact with copper metal, copper alloys, or the various salts of copper. Such improvement provided by my invention is demonstrated by the example given hereinafter in connection with the reduction of the copper dish'gum specification attributable to the process, and can be demonstrated in various other ways.

A further object is a method of producing a substantially gum-free, refined, cracked distillate of improved color, odor and sulfur content, which process does not affect the distillation range of the cracked distillate undergoing treatment, and which does not necessitate a subsequent redistillation step inorder to produce the improvements indicated.-

Another object is to provide a process of the character described which may be carried out substantially at atmospheric temperatures and pressures with relatively small quantities of treating agent, the improvement being effected in-a relatively short period'of treatment, and with minimum requirements for equipment, reagent and power.

1 Other objects will be apparent as the invention is hereinafter more fully described.

I have found that the foregoing objects may be accomplished in accordance with the present invention, one aspect of which involves intimately contacting cracked distillate in the liquid phase with an acid of phosprous, the acid treatment being carried out under conditions sufficiently mild sothat thedistillation range of the material undergonig treatment is substantially unaffected, but within a temperature range sufiicient to bring about the desired improvement in specifications. Contrary to all indications of the prior art, I have found that these results may be obtained, in the case of cracked distillates, by carrying out the acid treating step at a temperature above approxirange as the original untreated cracked distillate, the entire refining process being carried out without the necessity of redistilling the cracked distillate after the acid treating step.

The acid or acids of phosphorus'employed in accordance with my invention may vary in strength between wide limits, for example, from 10% to 95% strength acid. I prefer; however, to employ acids having a strength above 50% (the stronger acids being less corrosive to steel) but below 85% strength (the syrupy acids being viscous and generall more difiicult to handle) The 75% phosphoric acid of commerce is especially desirable for use in accordance with the present invention, because of its ready availability;

The treatment of the cracked distillate with the acid may be carried out at temperature-ranges of from 0 F. to 200 F. However,,for ease of handling and for best resultslprefer to-us'e a range of from 32 Ffit'o 130 R, which range may be regarded as essentially atmospheric. sure employed in the process is merely sufficient to retainthe cracked distillate-in the liquid phase during the acid treatment, from zero pounds basis, I have found that 0.05% to-0.5% of phos-- phoric acid gives very satisfactory results,- the improvement in thespecificationsof thecracked distillate being very definite and increasing as the proportion of phosphoric acid is increased, up;-

to-approximately 0.5%

The time of'contactbetween the cracked dis tillateand the acid is fairly important, atleast" one minute contact time being essential. Ingen eral, a contact time of from five minutes to fifteen minutes is satisfactory. If the-time'of contact is shorterthan five minutes, usually the. full bene fits ofthe process are not att'ained,.while contact, time inexcess of fifteen minutes generally-givesno further improvement. These'figuresarebased on intimate contact wherein'the acid i'sbroken'up: into a fine spray of droplets or int'o'amisttwithin the body of the oil being treated. In order more fully to disclose: the nature 0 the present invention, a preferred embodiment.

thereof will hereinafter be described; "Itshould be'clearly understood,.however, that this is done solely for purposes of illustration, and is. not to. be construed as a limitation uponthe spiritor scope of my invention.

One of the simplest and. yet one of the most efiective commercial applications ofv the present invention may be carried-out by placing the oil to be' treated in an open or vented vessel'provided with an agitator ..and thereafter'adding therequired volume of phosphoric acid; After-the: acid is added, intimate contact of the reagent;-

with the distillate is effected by suitable means,

for example, by vigorous agitation, stirring, blows" The presing with air orv gas, circulating by pumps, or any equivalent means. The vessel preferably has a cone-shaped bottom to facilitate drawing off the products of reaction, and may be made of any material fairly resistant to the phosphoric acid employed. In practice, I have found it advisable from the standpoint of cost to employ steel vessels and to add to the acid anyof the readily available commercial phosphoric acid inhibitors to prevent excessive corrosion of the steel. Such inhibitors may be obtained from the Victor Chemical. Works or from The Monsanto Chemical Company.

'- After the required contact time between the acid and the distillate, the components of the mixture are separated, the sludge and unused acid beingdrawn off and the treated distillate placed in storage. Redistillation of the acid treated roduct is unnecessary when carrying out the process of the present invention, since the boiling range is unaffected during the treatment, and the specifications of the acid treated product are greatly improved, directly and-withoutfractionationof the product. If preferred, a water washe ing step may be employed immediatelyfollowing'the acid treatment, such water-washing; step generally facilitating the separation of the acid from the treated distillate.

Example 'As an example of the efliciency of-the present invention, the results of one experimentmay be given. A sample of crackeddistillateotboiling range 325 F. to 465 F., of 2 NPA color, ofiun, pleasant odor, of gum content of.,1000..mgs.,'.per. 100 cc. when evaporated in a copper dish at' 207 F. at a pressure, of 0.075 inchof'water less than atmospheric, and of a total sulfur content of. 0.16%. was treated for fifteen minutes with 0.2% by volume of 75% phosphoric acid. .The mixture. was allowed to settle and then washed with 'water. The separated cracked. distillate. showed no change indistillation rangeas-aresult of thejtreatment, no change in octane num:

dition, whereas the original untreated cracked distillate darkened to 3 NPA color Withintwo, months after the date of the treatment of the,

withdrawn sample, the treated sample had, during the same period, darkened only to. 1 /2 NPA color.

v.If desired, commercial gasoline inhibitors deactivators may be added to the treateddistilfl late in order further to improve the specifications. of the product. Such supplemental treatment by addition of inhibitors, however, in no way dispenses with the acid treatment.

By reason of the factthat the acid treatment:

is carried out in accordance with the present invention, under relatively mild temperature con-- ditions, violent reactions are avoided, with. the result that the improvement in the specifications hereinbeforepointed out is accomplished'without; the necessity of subsequently redistilling the product toremove the heavy polymerizedor condensed by-products resulting from the more ener-,

getic treatment of the prior art. Sinceredistillation is unnecessary in orderto produce'a refined cracked distillate of the same boiling range as the 1 untreated material, it will be apparent that the: process of the present inventionzefiects a material reduction in the cost of refining cracked distillates, this being brought about bothby reduction 'in the amount of equipment-{required and also by the elimination of' the expense of' treatingthe distillate at elevated temperatures and subsequently redistillingthe samel It is, of course, apparent that the treated distillate produced in carrying out the'process of the present invention maybe subjected to fractional distillation ifit is desired to produce various boiling fractions thereof. However, where an ultimate product is de sired which possesses the same boiling range as the original cracked distillate, redistillation of the treated distillate after the mild acid treatment of the present invention is wholly unnecessary, inasmuch as my improved process produces directly and without the necessity of a subsequent distillationstep, a substantially gum-free refined distillate of improved-color, odor, and sulfur content, the entire refining process being carried out without redistillation of the acid treatedmaterial.

The terms cracked hydrocarbon distillate or .cracked petroleum hydrocarbon distillate as used in the specification and claims refer to cracked distillate products such as cracked kerosene, cracked naphtha, cracked distillates or fractional cuts thereof, and do not include concentrates rich in resin-forming unsaturated hydrocarbons, such as crude indene, crude styrene, and similar products capable of polymerization to form resins which may be separated from cracked hydrocarbon distillates.

In the foregoing detailed description, it will be apparent that many variations in detail may be made without departing from the spirit and scope of the invention. Thus, for example, the operator may employ any of the acids of phosphorus heretofore used in the prior art, for example, the meta and pyro phosphoric acids, various sulfoacids of phosphorus, and the like. Likewise, the method of effecting intimate contact between the acid and the distillate may be modified as desired; for example, by passing a fine stream of hydrocarbon through a relatively small volume of phosphoric acid, using a countercurrent flow principle. The process may be effected continuously or in a batch type of operation, as preferred. The temperature range may be varied within wide limits from to 200 F., although it is essential to maintain the temperature below the maximum indicated, in order to obviate the necessity of redistilling the treated product to obtain a product of the same boiling range as the original starting material. The apparatus used is entirely a matter of choice, since the invention is in no way restricted to the nature of the equipment employed. Many other variations in detail will be readily apparent to those skilled in the art. I, therefore, intend to be restricted only with the following patent claims.

I claim:

1. A method of refining cracked hydrocarbon distillate having a boiling range between about 300 F. and about 600 F. and of such composition that such distillate is rendered unstable and of higher boiling range by treatment with sulfuric acid, which method consists in intimately contacting said distillate in the liquid phase with a phosphoric acid while maintaining said distillate at a temperature below approximately 200 F.; and thereafter separating the treated distillate from said acid to produce directly a substantially gum-free and gum-stable refined cracked distillate of improved color, odor and sulfur content and-of substantially the same boiling range'as said distillate prior to treatment .with said acid of phosphorus.

"The method of claim 1, wherein saidacid treating step is carried out at a temperature range between approximately 32 F. and approximately'130 F.

' 3. The method of claim 1, wherein said acid treating step is carried out at a pressure varying from approximately zero pounds gauge to approximately 50 pounds gauge.

a 4. The method of claim 1, wherein said acid treating step iscarried out for a'period varying from approximately one minute to approximately fifteen minutes. I

5. The method of claim 1, wherein said acid comprises.75% phosphoric acid, employed inproportions ranging from approximately 0.05% to approximately 0.5% by volume, based on the quantity of distillate being treated.

6. A method of refining cracked hydrocarbon motor fuel distillate having a boiling range between about 300 F. and about 600 F. and of such composition that such distillate is rendered unstable and of higher boilingrange by treatment with sulfuric acid, which includes intimately contacting said distillate in the liquid phase at a pressure of from 0 pounds gauge to 50 pounds gauge, with from 50% to strength phosphoric acid, while maintaining said distillate at a temperature between approximately 32 F. and approximately F., for a period between about 5 minutes to about 15 minutes; permitting the acid-distillate mixture to settle; washing the mixture with water; and thereafter separating the treated distillate from the acid to produce without further chemical treatment, a substantially gum-free and gum-stable refined distillate of improved color, odor, and sulfur content, and of substantially the same boiling range as said distillate prior to treatment with said acid of phosphorus.

7. The method of claim 6, wherein said phosphoric acid is employed in the proportions by volume ranging from approximately 0.05% to approximately 1%, based on the quantity of distillate being treated.

8. A method of refining heavy cracked petroleum hydrocarbon distillate having a boiling range between about 300 F. and about 600 F. and of such composition that such distillate is rendered unstable and of higher boiling range by treatment with sulfuric acid, which method consists in intimately contacting said distillate in the liquid phase with an acid of phosphorus while maintaining said distillate at a temperature below approximately 130 F. and thereafter separating the treated distillate from said acid to produce without further chemical treatment a cracked distillate substantially improved in its stability toward the formation of varnish-like gum in the presence of copper containing materials, and of substantially the same boiling range as said distillate prior to treatment with said acid of phosphorus, the entire process being carried out without redistillation of the distillate following said acid treating step.

9. In a method of refining heavy cracked petroleum hydrocarbon motor fuel distillate having a boiling range between about 300 to about 600 F., the steps of intimately contacting said distillate in the liquid phase with phosphoric acid while maintaining said distillate at a temperature below approximately 130 F. and thereafter separating the treated distillate from said acidto form directly a substantially gum-free refined cracked distillate of improved color, odor and sulfur content having improved resistance to formation of gum and having substantially the same boiling range as said distillate prior to treatment with phosphoric acid.

10. In a method of refining cracked petroleum hydrocarbon motor fuel distillate having a boiling rangebetween about 300 to about 600 F. and of such composition that the distillate is rendered unstable and of higher boiling range'bytreatment with sulfuric acid, the steps of intimately conapproximately zero pounds gauge to approachmately pounds gauge. I V I 12. The method of claim 10 wherein said acid comprises phosphoric acid employed in proaportions ranging from approximately 0.05%. t approximately 0.5% by volume based on the quantity of distillate being treated. 1

13. In the process of refining cracked hydro..-

- carbon distillate having a boiling range between aboutv 300 F. and about 600 F. and of such com? position that such distillate is rendered unstable and of higher boiling range by treatment with sulfuric acid, said distillate being suitable asfuel for an' internal combustion engine, by intimately contacting thesame in the liquid phase with an acid of phosphorus and thereafter separating the acid-treated distillate from the acid, theimprovement which consists incarrying out such process.

at a temperature below 200 F. for a period. of at least one minute, to produce directly a substantially gum-free and gum-stable refined distillate of improved color, odor and sulfur content, but of the same distillation distillate.

CARL WILLIAM BERGER.

range as the untreated