US2057432A - Treatment of hydrocarbon oils - Google Patents

Description

aiented Oct. 13, 1936 TREATMENT OF HYDROCARBON OILS Vladimir Ipatieff and Aristid V. Grosse, Chicago,

11]., asslxnors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application October 26. 1932,

Serial No. 639.616

6 Claims.

This invention relates to the treatment of hydrocarbon oils and refers more particularly to the treatment of the low boiling naphthas and gasolines produced from crude petroleums by fractionation under conditions involving substantially no cracking.

In a more specific sense the invention has reference to a process for treating said straight run" gasolines to improve their quality with respect to gum and color-forming compounds present and in a specific sense in regard to improving their anti-knock value and yield.

In a general way the gasoline fractions present in crude petroleum and which may be removed therefrom by fractionation at moderate temperatures and pressures reflect the characterof the crude petroleum, that is, the proportions of such hydrocarbon groups as paraflins, olefins, naphthenes, aromatics and the sulphur and nitrogen compounds vary with the type of crude.

Although there are cases of considerable divergence from this rule, the gasolines from paraffinic crudes such as those from the Pennsylvania and some of the Mid-Continent fields are highly parafiinic and hence highly knocking in character. The gasolines from the Mid-Continent field crudes and some of the Gulf crudes have an intermediate character in respect to' anti-knock value, indicating possibly the presence of rela- 30 tively higher percentages of cyclic compounds of the nature of naphthenes or of isoparaflms. Certain crude oils from the Pacific Coast producing areas and some Texas fields yield gasolines of comparatively high anti-knock value, owing to the cyclic character of the crude oils. These observations as to the variable character of straight run gasolines are merely adduced in a general way to show that different gasolines or naphthas may require different degrees of treatment ac- 40 cording to the process of the invention to be presently disclosed in order to render them up to the prevailing market standards for anti-knock value. The present invention comprises a process of treatment whereby the character of the hydro-' the present invention comprises any compound of carbon and hydrogen of open chain structure and con aining one or more double bonds between car on atoms. The following tabulation gives a few of the lower boiling members of the ethylene series which consists of homologs of the base substance ethylene containing one double bond.

Table No. 1

Boilln Compound Formula points lgthyk ne gglzgflafi 102.7

ropy one -48 Ethyl ethylene (n-butyoniomcncn, -E

ene Plane-sym. dimethyl +1 ethylene. CHrCH=GH-CH| Axial-sym. (iso-butylene)- +2.5 Unsym. dimethyl ethyl- (CH:):C=CH| 6 ene (iso-butylene). n.Pro1iyl e)thylene (alpha- CHiCH:GH:CH=CH +39 may one Isopropyl ethylene (alpha- (CHzhCH CH=GH;.---- +21 isoamylenc Sym. methyl ethyl ethyl- GIL-CH;- CH=CH-CH|.- +36 one (beta-amylene).

r(nethyl ethyl OHx-CH: e y one gamma-amy mm on CCH2 +31 Trlmethyl ethylene (beta- (oH.),c cH-om.. +36

isoamylene Tetramethyl ethylene (CH:):C=C(OH:): +73

- of the double bond and the presence of tertiary or quaternary carbon atoms, the number of possible isomers increasing as the number of carbon atoms increases.

From. these considerations it is evident that, for the ethylene series alone, a large number of diiferent olefins may be employed either singly or in admixture for condensation with paraflin hydrocarbons according to the process of the invention.

The invention may further comprise the utilization of open chain unsaturated hydrocarbons of the acetylene or the diolefin series comprising such compounds as acetylene, butadiene, etc.,

and their homologs.

The catalytic materials whose use is comprised within the scope of the invention for causing the condensation of olefin with gasoline hydrocarbons constitute a special feature thereof and will be discussed in detail. The substances which we may employ alternatively either singly or in suitable admixtures are each of special value in furthering the desired synthetic reactions but the exact effect produced upon the speed and course of a given reaction by any substance or mixture of substances will be specific for the substance and not exactly equivalent in degree or in kind to other substances which may be employed alternatively to produce or influence the same reactions.

The catalysts which we have found useful may be divided generally into three classes:

1. Heavy metal halides such as those of aluminum.

2. Compounds formed by the union of certain heavy metal halides with hydrocarbons, these compounds having the formulas RAlXz or RzAlX where R is an alkyl residue and X is a halogen, particularly chlorine or bromine.

3. Compounds either of the formula AlXa- CaHnRe-n or AIXB'ClOHnRBfi in which X equals a halogen and R equals an alkyl radical.

The metal halides (generally the chlorides and bromides) which we prefer to employ in the production of the catalysts of the above classes comprise those of such metals as aluminum, tantalum (TaCls and TaBrs), antimony (SbClt), tin (SnCh), and tungsten (WCls) We are aware of the previous use of the halides of aluminum, particularly aluminum chloride (AlCla) and aluminum bromide (AlBra) in effecting the condensa tion of alkyl halides and olefins on the one hand with aromatic hydrocarbons such as benzol, toluol, naphthalene, etc., on the other hand to form alkyl-substituted aromatics, according to reactions disclosed in 1877 (Friedel and Crafts). The use of the halides of aluminum alone in effecting the addition of olefins to the hydrocarbons in gasoline is comprised within the scope of the present invention which also includes .the use of organo-metallic compounds of these halides and the others mentioned, these compounds being described in the succeeding paragraphs.

We have indicated the composition of one class of the mixed organo-metallic catalysts which we may employ alternatively with aluminum and other metal halides by two formulas, to-wit: RAlXz and RzAlX. Compounds of this character may be employed by themselves or in conjunction with halides of aluminum or the other metals previously stated when it is desired to induce and accelerate specific alkylation reactions upon particular gasolines.

The following particular example illustrates the general method of preparation of this class of mixed type compounds. 1'70 parts by weight of normal propyl iodide, 24 parts by weight of dry magnesium turnings and 200 parts by weight of benzol may be heated together at moderately elevated te nperatures in the neighborhood of the boiling point of water until a large part of the magnesium is converted into magnesium propyl iodide which appears as an insoluble white powder. The solvent, in this case the benzol, may then be decanted and the precipitate treated with about parts by weight of aluminum bromide and 180 parts by weight of fresh benzol, these ingredients being heated in an atmosphere of nitrogen at C. for some time. After this initial heating the temperature may gradually be raised to some point between and 200 C. (utilizing pressure if necessary to prevent loss of volatile materials) and the products of the reaction may then be distilled in vacuo. After the removal of any excess benzene by distillation a heavy colorless liquid then distills, which represents one of the many compounds which may be produced for catalytic work by this general method of procedure. As indicative of the probable course of the reactions in the last step of the catalyst preparation the following equation is suggested:

The complex indicated as the first substance on the righthand side of the equation is of somewhat indefinite composition in respect to the benzol content, hence the use of the X. Complexes of this character are colorless or light brown or yellow liquids which can be distilled in vacuum with slight decomposition and are very reactive, reacting vigorously with water to form aluminum oxide and hydrocarbons. Obviously by the use of other alkyl and aryl residues than the propyl residue in the above example and by the use of other aluminum halides and other aromatics instead of benzol a great variety of complexes may be employed which have catalytic value when used to assist in condensing olefins and paraffins. Owing to the complexity of many of the reactions in which the halides of aluminum and other heavy metals play an active part, it may sometimes happen that the alkyl or aryl residue is partially halogenated. However, such side reactions seldom exert any deleterious effect on the properties of the mixed catalyst produced and for all practical purposes may be disregarded.

In regard to catalysts of the third class previously mentioned such complex compounds are formed by first dissolving an aluminum halide such as aluminum chloride and aluminum bromide in an aromatic hydrocarbon. When reaction is brought about by the introduction of halogen acids such as hydrochloric acid at ordinary or somewhat elevated temperatures, a heavy viscous orange-colored layer separates gradually which has the general formula A12Xe.6R in which X equals a halogen and R. equals an aryl hydrocarbon. These compounds may be employed to produce active catalysts for alkylation reactions corresponding to the general formulas given in Class 3 by introducing gaseous olefins which form the true catalytic material of the given formulas by the partial alkylation of the combined hydrocarbons. It will be obvious from a consideration of the formulas that many individual compounds may be designated thereby corresponding to different degrees of hydrogen substitution by different alkyl groups. In addition to the groups contained in the formulas as given there is some further combination with the original aromatic employed to form a loose addition compound. When utilizing olefin mixtures such as might be encountered in gases from oil cracking processes the catalyst which is produced and which acts as intermediary for the transfer 01 alkyl groups to the hydrocarbons in a hydrocarbon mixture may be of a mixed character and difllcult of exact analysis.

The invention comprises the use of definite individual compounds of the types described above and th: use of mixtures of variable composition with the percentage of the different components adjusted to produce optimum effects upon any given reaction or set of reactions. Obviously each particular individual compound or mixture of compounds will exert its own special catalytic influence in any given case and not be exactly equivalent to the action of the other substances which may be used alternatively. In the case of catalytic compounds which may be produced from aluminum halides it appears certain that a greater catalytic activity is evinced by derivatives of dues.

these starting materials which are formed as the reactions proceed. For example, we have evidence to the eifect that in the case of a compound oline. Obviously the ethyl groups present in the above mentioned compound originated from the ethylene. When other olefins or mixtures of olefins are employed, the composition of such active catalysts will vary correspondingly.

Catalytic compounds may be produced from aluminum halides and any homolog of benzol or polynuclear hydrocarbons such as naphthalene, anthracene, etc., insofar as their physical properties in regard to melting, boiling and decomposing temperatures may permit.

The reactions involved in treatments according to the process of the present invention are of great complexity owing to the large number of hydrocarbon types represented in the gasolines treated on the one hand and the large number of olefins which may be employed on the other hand to alter the character of the gasoline. Merely to exemplify to some extent the character of the reactions which may occur, those which take place when a single olefin such as ethylene is caused to join with benzol to produce an alkylated derivative may be considered. When ethy-' lene is passed into a well agitated mixture of benzol and catalysts of the nature described in Classes 1 and 2, the benzol is ethylated to an extent depending upon the efliciency of contact of the gas, the temperature, pressure and the time over which the reaction is allowed to proceed. The initial stage of the alkylation may be represented by the following equation:

Ethylene Ethylbenzene Ben- 201 Further additions of the ethylene will produce in succession the poly-ethyl derivatives of benzol and possibly hydrocarbons of less definite composition owing to the probable shifting of hydrogen atoms in both the alkyl and the benzene resi- In the above reactions ethylene represents any of the homologs of ethylene, and benzol represents any of the aromatic series of hydrocarbons and may also typify the polynuclear derivatives such as naphthalene and anthracene. ever, the proportion of such polynuclear derivatives is undoubtedly very small in straight run gasoline fractions which commonly boll under 437 F.

Catalytic substances whose use constitutes a feature of the present invention are effective in inducing and accelerating reactions between olefins and both paraflin and naphthene hydrocarbons as well as aromatic hydrocarbons. As a means of developing the character of the invention in respect to the alkylation of these more or less unreactive hydrocarbon groups it is only necessary to mention that they resemble each other to some extent in that the base members of both groups are without double bonds between carbon atoms though paraflins are distinguished from the naphthenes in being of a straight chain rather than of a cyclic character.

The paraflin group comprises a complete series of compounds from methane upward in which the HOW- carbon atoms are assumed to be arranged in straight chain, and another complete isomeric series beginning with four carbon atom compounds in which the straight chain arrangement is modified so that there is a carbon to carbon bond which is out of the main line of carbon atoms. Thus with increasing number of carbon atoms the number of possible space isomers increases and also the complexity of the molecule. When using the types of catalysts according to the process of the present invention, olefin.

hydrocarbons may be added directly to any of the types of paraflin or naphthene hydrocarbons, the following elementary and .simplifled equations representing the reactions which take place:

Ethyl- Home one Ethyl hexane CsHH-CtHu CtHn- CIHI Ethyl- Hexaene methyl- Owing to the existence of hydrocarbons of mixed type which may possess predominatingly the characteristics of some one general group and less markedly the characteristics of another group, the exact course of aikylation reactions is very complicated and can only be followed by observing the increase in anti-knock propefties and changes in boiling points.

It is recognized that in all cases where olefins are contacted with condensing agents of the character described that there is a tendency for polymerization to occur among the olefins themselves as well as for them to enter into the alkylation reactions described. However, these reactions may be controlled by proper contacting of the oleflnic hydrocarbons with the gasoline hydrocarbons so that there is a decreased tendency toward the formation of compounds of high molecular weight. Owing to the low formation of tarry polymers observed in practicaly all cases it is probable that if polymerization reactions occur that they do not pass beyond the stage of dimers and trimers which of themselves are valuable compounds and add anti-knock value to the gasoline hydrocarbon mixture.

A commercial application of the process of the Ethyl naphthene invention is well exemplified in the treatment of a straight run gasoline with the gases from a cracking process. In such operations several modes of procedure will present themselves to those conversant with commercial practices. In a simple case, some liquid catalyst is selected from the many alternatives which are comprised within the scope of the invention and this may be kept in suspension by agitation in a stationary body of gasoline in a batch agitator while a stream of olefin-containing gases is bubbled through the suspension through a spray or other distributing means. It may be preferable to have cooling coils immersed in the reaction mixture so that excessive temperature rise is avoided.

The use of towers makes possible continuous operation, the catalyst, olefinic gases and gasoline being separately injected into a mixing box of some character at the top of the column and the mixture allowed to flow by gravity down over pans or perforated plates so that more or less complete reaction is assured by 'the time the reaction constituents reach the bottom of the tower. In some cases the catalyst and gasoline may be caused to flow downwardly and the stream of olefinic gases directed upwardly through the tower to effect a counterfiow treatment.

As an example of the results obtainable commercially by the use of the process the treatment of a light fraction of a straight run Pennsylvania gasoline with gases from a cracking plant may be cited. The light fraction may boil between the approximate ranges of and F., and may be treated with a gas mixture containing approximately 40% of ethylene and its homologs in the presence of a. catalyst made from aluminum bromide and benzol according to the method heretofore described for manufacturing catalysts of Class 2. After passing in the gas until the volume of the original fraction has increased two and one-half times, the boiling range may then be from 90 to 400" F., and the product mayhave an anti-knock value expressed as octane number equal to 78. Since the synthetic gasoline thus produced is free from tars and polymers and organic chlorine compounds it may be used directly as a premium motor fuel.

Similar treatments may be conducted upon gasoline fractions of more extended boiling range and the synthetic compounds boiling within the proper range may be separated from the total product with approximately the same increase in yield. JIhe alkylated compounds of boiling range higher than that desired in the gasoline may be either cycled to a cracking or reforming plant along with fresh charging oil or may be blended with fresh fractions of gasoline to be alkylated, under which circumstances some of the substituted alkyl groups are transferred from the high to the low molecular weight compounds forming intermediate fractions of desired characteristics.

The foregoing specification has described and disclosed the general and broad character of the invention and the example is sufficiently indicative of its value from a commercial standpoint. However, the invention is not limited in scope to the exact details of the descriptive material or the experimental data given.

We claim as our invention:

1. A process for increasing the anti-knock value of light petroleum distillate containing hydrocarbons within the gasoline boiling range, which comprises reacting at least a portion of said hydrocarbons with an olefin in the presence of a heavy metal halide catalyst selected from the group of compounds having the formulas RMXz,

wherein M, X and R equal, respectively, a heavy metal, a halogen and an alkyl radical.

2. A process for increasing the anti-knock value of light petroleum distillate containing hydrocarbons within the gasoline boiling range, which comprises reacting at least a portion of said hydrocarbons with an olefin in the presence of a. heavy metal halide catalyst selected from the group of compounds having the formulas RAlXz,

wherein R and X equal, respectively, an alkyl radical and a halogen.

3. A process for increasing the anti-knock value of light petroleum distillate containing hydrocarbons within the gasoline boillng range, which comprises reacting at least a portion of said hydrocarbons with an olefin-containing gas in the presence of a heavy metal halide catalyst selected from the group of compounds having the formulas RMXz, RzMX, MiQi'CfiHhRB-h, and

wherein M, X and R equal, respectively, a heavy metal, a halogen and an alkyl radical.

4. A process for increasing the anti-knock value of light petroleum distillate containing hydrocarbons within the gasoline boiling range, which comprises reacting at least a portion of said hydrocarbons with an olefin-containing gas in the presence of a heavy metal halide catalyst selected from the group of compounds having the formulas RAlXa, RzAlX, AlX3'C6HnR6-n, and

wherein R and X equal, respectively, an alkyl radical and a halogen.

5. A process for alkylating hydrocarbons which comprises reacting the hydrocarbon to be alkylated with an olefin in the presence of a heavy metal halide catalyst selected from the group of compounds having the formulas RMXz, RzMX, MXIi'CBHnRB-n, and MXa-CmHnRa-n, wherein M, X and R equal, respectively, a heavy metal, a halogen and an alkyl radical.

6. A process for alkylating hydrocarbons which comprises reacting the hydrocarbon to be alkylated with an olefin in the presence of a heavy metal halide catalyst selected from the'group of compounds having the formulas RAlX2, RzAlX, AlXa-CsHnRs n, and AlXIl'ClOHnRB-h, wherein R and X equal, respectively, an alkyl radical and a halogen.

VLADIMIR IPATIEFF. ARISTID V. GROSSE.