US2063082A - Treatment of hydrocarbon oil - Google Patents

Description

Dec. 8, 1936. R 5 DAY I 2,063,082

TREATMENT OF HYDROCARBON OIL Original Filed May 25, 1932 3 sheets sheet l furl/amine FIGJ.

Dec. 8, 1936. R. B. DAY

TREATMENT OF HYDROCARBON OIL Original Filed May 25, 1932 3Sheets-Sheet 2 NGE mIZumI k mumkwufl mmPFumSuh cow com 00 OOH com com BDFIVD SGNflOd HUFISSBHd Dec. 8, 1936.

LBS. OF 37% AQUEOUS HCL PER BBL. OF GASOLINE p R. B. DAY.

TREATMENT OF HYDROCARBON OIL 7 Original Filed May 25, 1932 3 She ets-Sheet 5 HYDROCHLORIC ACID QEQUIIZEU FOD. TREI-TMENT' FIGS.

ewe: DRESSUIZE,LB$. PEIZ SQUARE iNCH GOO 25M jz orzzeg,

I Patented I Dec. 8, 1936 PATENT OFFICE TREATMENT OF HYDROCABBON OIL Roland B. Day, Chicago, 11]., assignor to Universal- Oil Products Company, Chicago, 111., a corporation of Delaware Application May 25, 1932, Serial No. 613,518

' Renewed May 20, 1935 Claims.

This invention relates to the treatment of hydrocarbon oils and refers more particularly to the treatment of hydrocarbon oil distillates of motor fuel boiling range produced by the crack- 5 'ing of heavier and less valuable portions of petroleum oils though similar motor fuel fractions produced from other sources may also be treated such as those produced in the straight run distillation of crude petroleums or in the cracking of tars produced in the primary distillation of coals, shales, etc.

In a more specific sense the invention is concerned with a process which may be employedto controllably eliminate the undesirable constituents of primary or untreated motor fuel distihlates, such constituents being classified generally as the gum-forming and colored compounds and the sulfur-containing derivatives, the latter imparting a bad odor to the distillates, and being corrosive upon the metal parts of automobile engines either before or after combustion.

The most generally used refining method for producing a refined and stable gasoline from primary naphthas consists in "regulated treatment of the same with concentrated sulfuric acid, followed by neutralization (with sweeteningif necessary) and redistillationto produce refined gasoline as an overhead product. The disadvantages of this method lie generally in the cost of reagents and particularly in the high losses suffered in accomplishing the desired degree of refining. The present invention is a departure from the older'method and possesses new and useful features which further diflerentiate it from previous attempts to overcome the difliculties encountered in producing a stable refined gasoline from the raw naphthas produced in cracking operations with minimum losses. Other features and advantages will become evident in the development of the specification.

In one specific embodiment the invention comprises the treatment of hydrocarbon oil distillates, particularly cracked hydrocarbon oil distillates of approximate motor fuel boiling range at elevated temperatures and under pressures sufficient to substantially prevent vaporization of said distillates with hydrochloric acid and metal chlorides.

A number of metal chlorides are particularly suitable for use in the process such as those of zinc, tin, iron, aluminum, etc. The treating effect produced by any particular metal chloride or mixture of metal chlorides .which may beemployed in conjunction with hydrochloric acid in the process will be distinctive in any case so From to or in order of diminishing tendency toenter the ionic from the elementary state Potassium Sodium Barium Calcium Magnesium Aluminum Manganese Zinc Chromium Ir on Cadmium Cobalt Nickel Tin Lead Hydrogen Antimony Bismuth Arsenic Mercury 7 In numerous instances it has been observed that the polymerizing or gum-reducing effect of the treatment is roughly proportional to the amount of electropositive metal chloride in mixtures of one or more chlorides while the desulfurizing effects are promoted in proportion to the amount of electronegative metal chloride though this observation cannot be laid down as an invariable rule.

. An important feature of the invention appears in the fact that while treatments are conducted at elevated temperatures that sumcient pressure is held upon the system to maintain the oils in substantially liquid phase. I havedetermined that when treating cracked distillates that unexpectedly good treating effects in regard to selective removalof gum-forming compounds and sulphur reduction are produced when utilizing temperatures within the approximate range of 500 and 650 F., the pressure required to maintain cracked distillates containing substantial amounts of gasoline boiling range fractions in liquid phase being of the order of from 400 to 500 lbs., per square inch under these temperature conditions. The exact temperature employed in the treatment will depend upon a number of factors, particularly upon the chemical composition and boiling-range of the naphtha or gasoline undergoing treatment and the metal chloride or mixture of metal chlorides which may be selected for use in conjunction with hydrochloric acid.

The beneficial effects of pressure 'sufilcient to insure substantially liquid phase conditions may be due to several causes. It is probable that the reactions of polymerization and desulfurization proceed with greater velocity in the liquid phase and under increased pressure conditions. At the same time the capacity of treating equipment for permitting a sufficient time factor is lowered so that the construction of suitable equipment is less costly than if any appreciable degree of vaporization is permitted.

When stabilized distillates are employed which are substantially free "from dissolved gases and low boiling hydrocarbons whose critical temperatures may be below the temperatures employed in the treatment, considerably lower pressures may be employed than when unstabilized or poorly stabilized distillates are employed. The curves shown in Fig. 2 indicate the limit conditions of operation which must be'adhered to in treating two gasolines of 114 and 128 mean molecular weight respectively if substantially liquid phase treating conditions are to be maintained.

.The nature of the reactions which have been found to produce the unusually good refining effects upon cracked gasolines when treated according to the process of the invention is dim cult of exact determination on account of the complex character of the hydrocarbon distillates, particularly in regard to the chemical nature of the gum-forming compounds and the form of combination of the sulphur which is present. It may be assumed that the gum-forming compounds consist to a large extent of diand triolefins of a conjugated character since these compounds are known to readily undergo polymerization. The sulphur compounds may be mercaptans, sulfides, disulfides, thioethers, thiophenes, etc., besides hydrogen sulfide.

The following equations suggest a possible explanation of the course of the reaction of the treatment:

. Metal H H chloride H RC=CR' H0! RCHPEJIR' (1) Gum- Catalyst forming 4 olefin Intermediate chlorine derivative Metal r H chloride H RCEh-CR' RH RCHz-OR' H01 (2) Cl Catalyst R" Polymer It is assumed that hydrochloric acid is the active material in producing reactions of polymerization among compounds such as the diand tri-olefins which are present in cracked distillates, the metal chloride present functioning catalytically. However, it is possible that the re action involve some formation of intermediate additon compounds between the metal chlorides and the hydrocarbon radicals. The determination of the exact course of the reactions of the treatment is beset with great difliculties both from the experimental and analytical standpoint. Apparently a very small amount of moisture must be present to insure efiective treatment, the necessary quantities being introduced along with the hydrochloric acid. The addition of any excess of water above a certain minimum requirement has been found to be quite uniformly detrimental to the efiicacy of the treatment.

To account for the extraordinary efiiciency of the process in. removing sulphur from cracked distillates which are refractory from the standpoint of ordinary sulphuric acid treatments, two types of reactions may be considered, the first involving polymerization of sulphur compounds along with the highly unsaturated hydrocarbons so that the sulphur appears in the heavy polymers and, second, those involving a preliminary combination of organic sulphur with a metal to form metal sulfide which is later decomposed by hydrochloric acid to evolve hydrogen sulfide as a gas.

These reactions are merely assumed and their proof would involve a series of diflicult analyses which if not impossible would add little value to the present specification. Some evidence is at hand to show that combined sulphur in high sulphur oils appears after the treatment in mercaptans as a result of secondary reactions of hydrocarbons with hydrogen sulfide originally formed. However, with suitable precautions which will be developed in connection with a description of an operation, this tendency toward mercaptan formation can be minimized. The unusual effects along the line of desulfurization will be referred to in the examples which appear later.

Very small amounts of hydrochloric acid are required in the treatments. From the equations given above the hydrochloric acid would be completely regenerated at the end of the polymerizing cycle so that the initial addition of a definite amount of acid would suffice. However, certain small losses are unavoidable and these are preferably counterbalanced by the addition of the necessary small amounts of acid.

There is apparently some definite relationship between the amount of hydrochloric acid necessary for efiicient treatment and the pressure employed upon the system which is shown by the curve in Fig. 3. An inspection of this curve indicates that at the preferred pressures, to wit, 400 to 600 pounds per square inch, that the consumption of hydrochloric acid is reduced to a practical minimum whereas it increases sharply at lower pressures. Aside from the efiect of greater concentration of the hydrochloric acid due to the use of higher pressures than have heretofore been employed in similar treating processes, it is possible that the hydrochloric acid functions with metal chlorides in a concentrated solution considerably above its maximum solubility in water at ordinary pressures. The treating eifects observed may thus be due to the joint action of hydochloric acid and metal chloride in the presence of extremely small amounts of moisture. The small amount of hydrochloric acid necessary for the'treatment may be added as a substantially dry gas or in concentrated solution.

The process may be conducted in any suitable type of apparatus and Fig. 1 shows diagrammatically by the use of conventional figures in side elevation the essential features of a plant layout which can be used.

Distillates to be treated may be introduced to the plant through a line I containing a control valve 2 and pumped by a pump 3 through a line temperature for treatment th'eheated products may be discharged through a line 8 containing a control valve 9 and leading to a line l0. Acid necessary for the treatments may be supplied to a pump [8 through a line l6 containing a control valve I 1 and discharged through a line H containing a control valve 20 into line I0 where it mixes with the heated oils. As previously stated the acid maybe introduced in a solution of proper concentration to insure the presence of the small amounts of water which are apparently necessary in the treating reactions or may be introduced as a substantially dry gas, the type of pumping equipment represented by number l8 being suitably modified.

The acid and oil pass under selected tempera; ture and pressure conditions within the ranges previously mentioned through valve H and enter pressure treater l2 which contains a metallic chloride contact mass [3 dividing the interior of the treater into upperand lower liquid spaces l4 and I5 respectively. During the passage of the oil and acid through the contact mass, degumming and desulfurizing reactions are effectedand the products of the treatment pass through line 2! containing control valve 22 to fractionator 23, valve 22 being so manipulated in conjunction with valves subsequent to the fractionator that the pressure obtaining on the pressure treater is substantialy reduced in the fractionator which may operate, for example, at pressures of from 50 to pounds per square inch. The chlorides employed may be mixed with or deposited upon relatively inert or adsorbent spacing materials which, comprise such substances as crushed firebrick, pumice, sand, diatomaceous earth, clays, fullers earth, etc., the use of the spacing material acting generally to preserve the structure of the mass so that any tendency toward fiuxing is substantially eliminated.

Higher boiling fractions than are desired in the finished gasoline appear in the fractionator as heavy polymer refiuxes and comprise high boiling and substantially unaffected hydrocarbon fractions which may have been present in the. raw naphtha if such was treated, and also polymers of olefins.

some sulphur may appear in the polymers in the case of high sulphur stocks and some of the original sulphur may be present in the fractionator in the form of hydrogen sulfide. It is frequently advantageous in the case of high sulphur oils to utilize pressure treaters in series, the hydrogen sulfide formed in the treating reactions in the first of such a series being vented before further contact is brought about, thus reducing the tendency for metalsulfide formation with corresponding depreciation in the value of the contact materials. By vent ing the fixed gases and thus removing the majority of hydrogen sulfide the formation of mercaptans may be reduced to a practical minimum so that the desulfurization is more efiective. Any hydrochloric acid which may be lost when the hydrogen sulfide and other low boiling hydrocarbons or fixed gases are released may be counterbalanced" by further additions of acid prior to the succeeding pressure treater. The vented gases may be passed through auxiliary beds of granulated metals and the chlorides and sulfides recovered if desired.

The refiuxes from fractionator 23 may be removed'through a line 24 containing a control valve 25 and disposedof in any suitable manner. In case these refiuxes are of fairly low sulphur content and otherwise suitable, they may be used as recycle stock in the cracking plant which may have produced the naphtha or gasoline treated.

The vapors and fixed gases from the fractionator may be conducted through a vapor line 26 containing control valve 21 and be cooled during passage through a condenser 28, the cooled gases and condensed gasoline passing through a rundown line 29 containing control valve 30 to a receiver and separator 3| which has a line 32 containing control valve 33 for the controlled release of fixed gases, a draw line 34 containing control valve 35 for the removal of the finished gasoline and a bottom draw line 36 containin control valve 31 for removal of water or aqueous solution which may accumulate in the receiver.

The field of application of the process is extensive and the examples of the results obtainable upon difierentstocks could be multiplied to a considerable extent. A few, however, will suffice toshow the advantages of the process over the more commonly used systems of treatment.

An untreated cracked gasoline made from a relatively high sulphur California charging oil may be treated in equipmentgenerally similar to that shown in Fig. 1 at a temperature of 550 F. and a pressure of 450 pounds per square inch. The contact mass employed in the pressure treater may consist of zinc and copper chlorides mixed with three parts by weight of pumice andused in the molecular ratio of approximately four to one, and hydrochloric acid may be, admitted to the 'treating zone at a rate corresponding to from 0.1v to 0.2 pound per barrel of finished gasoline, the small amount passing out of the treating zone being absorbed during passage of the treated oils and fixed gases through auxiliary beds of granulated zinc, The following table shows the relative properties of the raw or untreated gaso- Comparison of raw and treated baselines Raw Treated Color +30 glacier tstabiliiigo'uuf; 27

g. o gum cc.

Total sulphur %.-.Z..

Good

After 4 hrs. exposure to sunlight.

Comparison of raw and treated gasolines Raw Yellow Color stability M of gum/100 cc.

by copper dis 0. 07 Positive 402 Octane number -1 68 Induction period in oxygen bomb-minutes--.

After 4 hrs. exposure to sunlight. The results obtained by the process Treated 65 denced by the two preceding examples are striking from several standpoints. It will be observed that in both cases the color and color; stability were better than those obtainable even by the use of commercially prohibitive amounts of sulphuric acid as shown in other experiments. The gum content was reduced to a figure below that required in premium gasolines and the odor was perfectly sweet. In the first example the sulphur reduction is especially noteworthy since California. pressure distillates are notoriously refractory in regard to desuliurization by sulfuric acid or other methods of treatment.

The treating losses suffered were considerably less than I% in both cases and this fact coupled with the extremely high quality of the treated product is of itself sufiicient to recommend the process for the treatment of cracked gasoline of any character. The selectivity of the treatment in regard to the removal of gum-forming olefins without aflecting mono-olefins is evident from the second example in the maintenance of the octane number after treatment while the oxygen bomb test which generally indicates the stability of the gasoline on storage is raised to a point considerably in excess of the minimum of 240 minutes which is at present accepted as indicating a gasoline sufiiciently stable under average storage conditions.

The foregoing disclosure of the nature of the invention and the numerical data presented in support 01 its commercial value are sufiicient for their respective purposes but none of the particular details given are to be construed as imposing limitations on the process which is generally broad in scope.

I claim as my invention:

1. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphur its normal initial boiling point to the action of hydrochloric acid in the presence of a chloride of a metal electropositive to hydrogen and a chloride of a metal electronegative to hydrogen under sufiicient pressure to preclude substantial normal vaporization and maintain a substantial portion of the oil' in liquid phase during the treatment.

2. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphurcontent thereof which comprises subjecting the same at elevated temperatures substantially above its normal initial boiling point to the action of hy drochloric acid in the presence of a contact agent comprising a zinc chloride and a copper chloride under sufilcient pressure to preclude substantial normal vaporization and maintain a substantial portion or the oil in liquid phase during the treatment.

3. The process as defined in claim 1 further characterized in that said oil comprises a gasoline-containing distillate.

4. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphur content thereof, which comprises subjecting the same in heated condition and while substantially in liquid phase to the action of hydrochloric acid in the presence of a chloride of a metal electropositive to hydrogen and a chloride of a metal electronegative to hydrogen.

5. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphur content thereof, which comprises subjecting the same in heated condition and while substantially in liquid phase to the action of hydrochloric acid in the presence of a zinc chloride and a copper chloride.

ROLAND 3. DAY.

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