US2278677A - Catalytic reaction of olefins - Google Patents

Description

April 1, 1942 E. E. STAHLY Em 2,278,677

CATALYTIC REACTION OF OLEFINS Filed Dec. 2, 1938 DEHYDROGENATIO v'q' poLurrllgz ffnrlou /7 /C9 /0 Patented Apr. 7, 1942 v 2,278,677 CATALYTIC REACTION or OLEFlNS Eldon E. Stahly and Erwin M. Hattox, Baton Rouge, La., asslgnors to Standard Oil Development Company, a corporation of Delaware Application December 2, 1938, Serial No. 243,519

13 Claims.

This invention relates to improvements in the production of highly desirable components .of motor fuels and pertains particularly to the production of relatively low boiling saturated aliphatic hydrocarbons which have been found to be useful in the preparation of gasolines.

It has heretofore been proposed to produce motor fuel constituents according to a number of well known processes, such as thermal and catalytic cracking of heavier hydrocarbons, polymerization of normally gaseous olefins, followed by hydrogenation, treating of crude and straight run gasoline cuts with olefins to improve their octane number by alkylating the aromatic constituents thereof with normally gaseous olefins in the presence of various catalysts, such as phosphoric acid impregnated on kieselguhr, etc. It has been found possible to react paraflinc hydrocarbons with olefins to produce saturated hydrocarbons boiling within the motor fuel range. This reaction has been denoted as alkylation. It is therefore readily apparent that a saturated branched chain normally liquid paraffin may be produced directly by alkylating a normally gaseous branched chain paraflin, for example, isobutane, by treating such a compound with a normally gaseous mono-olefin without the necessity of including a hydrogenation treatment in the process as would be the case where a polymerization process had been used.

Another advantage of the use of an alkylation process in contrast to the well known polymerization process lies in the fact that the petroleum industry is constantly seeking methods whereby it may be possible to utilize by-products of the industry and in this respect, alkylat on is a d stinct advance in the art. Large supplies of field butanes, refinery C4 cuts from cracking units, debutanizer units, etc., each containing substantial quantities of gaseous olefins and paraffins, both straight and branched chain, are available. Such gaseous mixtures have heretofore been fed to polymerization processes which are able to utilize only the olefinic content of the mixtures. As a consequence, the industry has found it expedient to dehydrogenate the inert paraflinc gases coming from such units, to convert them to olefins and to then refeed these gases to the polymerization processes. Such a procedure is unnecessary in a comparable a1- kylation process, and the expensive dehydrogena tion of paraflins and subsequent necessary hydrogenation of the condensation products is eliminated, yet a gasoline of substantially the same or higher octane value is produced.

It is an object of the present invention to provide a process for the production of normally liquid acyclic hydrocarbons boiling in the gasoline range by reacting mixtures containing at least one mono-olefin under condensation conditions in the presence of catalysts containing binary and ternary inorganic compounds of uranium.

It is an object of the present invention to provide a process for the production at premium grade motor fuels by the reaction of saturated hydrocarbons containing at least one tertiary carbon atom and boiling below the desired gasoline range or mixtures thereof with monomeric mono-olefins boiling below the desired gasoline range, dimers, trimers, tetramers, etc. of said monomeric mono-olefins or mixtures thereof.

It is a further object of the invention to so carry out the alkylation of isoparafiins that it is possible to obtain substantially twice as large a yield of premium grade gasoline based upon the amount of olefins reacted as would be obtained in the conventional olefin polymerization processes.

To accomplish such objects, it is a feature of the present invention to carry out the reaction under optimum reaction conditions in the presence of alkylation catalysts which have been found to be particularly effective 'in promoting the desired reactions. It is obvious that the optimum reaction conditions will vary for each particular catalysts employed. In general, it may be said that alkylation conditions predominate when the feed rates are adjusted to provide longer contact time than would be used in corresponding polymerization reactions. Better yields of saturated products are obtained, however, where the olefin concentration is somewhat lower than in the corresponding polymerization reactions. This phenomenon is probably correlated with the fact that, in general, lower temperatures, i. e., about room temperature or slightly lower, have been found to be most advantageous in obtaining completely saturated products. -It was found that when the olefinic content of the feed stock was too high, the temperature rose too rapidly to be accurately controlled within the desired range and a lower yield of alkylated products resulted Also a very low temperature led to the formation of high molecular weight polymers while temperatures above F. led to the formation of lower boiling alkylation products.

Likewise, it was found that the more intimate the contact between the reactants, the higher the yields of alkylated products. The feed stock is preferably introduced into the reaction zone through jets, porous thimbles, turbo-mixers and the like.

It was sometimes found to be advantageous in the production of high octane saturated fractions suitable for motor fuels, to return to the reaction zone the heavier alkylated fractions and the fractionsboiling intermediate the reactants and the desired motor fuel fraction removed from the system as the final product. It is sometimes desirable to leave the products formed intermediate the reactants and the C: out in the final product since the Ca, Ca and C1 saturated hydrocarbons are readily volatilized and have excellent anti-knock properties. Likewise, any unreacted reactants are separated from the desired fraction and returned to the reaction zone. Increased yields of the desired fraction result whether this recycle-step is carried out continuously or intermittently, whether only part or all of the recycle stock is fed into the alkylation zone together with the fresh feed.

The invention is not limited to the use of reactants from any particular source. Single paramnic and oleilnic hydrocarbons may be employed. However, it is commercially more feasible to use mixtures of hydrocarbons containing the necessary paraflins and oleiins as part of their constituents. The reacted mixture from catalytic and thermal polymerization units, including the gaseous constituents thereof, may be directly introduced as reactants into the alkylation process of the invention. Gaseous mixtures evolved from catalytic and thermal cracking units may also be advantageously employed. It is an essential requirement in the practice of the invention that the feed stock contain at least one paraffin containing a tertiary carbon atom and preferably boiling below the boiling point of the desired final product fraction, and that the feed stock contain at least one mono-olefin. Partially dehydrogenated field butanes, refinery C3-C5 and C4 cuts, saturated parafiinic mixtures containing isoparafllns and which have been enriched with mono-olefins from extraneous sources, etc. are suitable. The invention contemplates the reactions of isobutane, isopentane, etc. with ethylene, propylene, normal or isobutvlenes, normal and branched chain amylenes, the dimers, trimers. tetramers, ete., codimers, cotrimers, cotetramers, etc., cross polymers, interpolymers, etc. of these olefins and the like. In particular, it is contemplated to react an isoparamn with a lower monoolefin such as ethylene or propylene. It is prefarable. tqjnsure high yields of alkylation products, to have between about 2 and about 12 mols of isoparaiiin in the reactor per mol of monoolefin present. Likewise, from 4 to 24 mols of isobutane should be contacted with each mol of diisobutylene, etc. This avoids excessive formation of high boiling compounds.

It has been found that certain novel catalysts effectively promote the alkylation reaction. In particular, the inorganic compounds of uranium have been found to promote the alkylation reaction. The compounds which have been found to.

be suitable are the oxides of uranium, the halides of uranium, such-as the chlorides and bromides, sulfates and phosphates. Uranium oxide, UaOa, has been found to be particularly effective, not

only in promoting the formation of saturated compounds, but also in the formation of polymers. The addition of small amounts of alkyl halide, such as ethyl chloride, the propyl chlorides or bromides, tertiary or secondary amyl chloride. have been found to promote the activity of these catalsyts. their effects being to increase the formation of Cs-Cn saturates at the expense of initially formed olefin polymers.

The catalyst may be deposited or impregnated on carriers such as clays, either natural or acid activated gels, such as alumina gel or silica gel. Bauxite, fullers earth. bentonite, kieselguhr, pumice, eelite, montmorillonite, Marsil, Tonsil, Super Piltrol, activated Floridin. etc., serve as excellent carriers for the uranium compounds above mentioned. Also, it is contemplated to use these uranium compounds deposited upon the carriers above mentioned in conjunction with the use of the alkyl halide promoters.

The percentage of uranium compounds deposited upon the various carriers may vary from between about l% and about 15%. but it is preferable to use from about 5% to about 10% of the weight of the carrier of uranium salts impregnated or deposited thereon. The optimum percentage of uranium salts or oxides, deposited upon the various carriers depends, to a large extent, upon the amounts of the various salts used and also to some extent upon the surface available of the particular carrier. Thus, a larger percentage by weight of uranium sulfates would be required than would be the case where the uranium halides were used, all other conditions remaining the same; also, the acid activated clays. where a siliceous body, such as eelite, is used. would require a smaller quantity of the uranium compounds than would be the case where the uranium compounds were used alone or impregnated upon or carried upon substances having a less degree of porosity and surface area.

The catalyst may be used in any suitable conventional form: that is, it may be deposited upon a gel carrier of extremely high porosity, said porosity having been increased by the admixing of the gel with carbonaceous substances such as cane sugar or carbon, and heating to oxidize of! these substances, thereby leaving a gel of increased porosity for any given density; or the catalyst may be admixed or impregnated upon highly activated clays, which are then pilled or I flnely comminuted and used in the reaction medium in the form of a powdered catalyst, or the catalyst may be admixed with a carrier and extruded through orifices of predetermined size. The catalyst mass may also be made up in the form of small pellets having the uranium compounds deposited thereon, or, if desired, the uranium salts may be used by themselves without the aid of any carrier, although this is not usually the preferred procedure.

The process may be carried out either as a batch or continuous run. It may be carried out in either the gas or liquid phase. Where it is carried out in the liquid phase, it is desirable to maintain sufficient pressure so that the reactants are in the liquid state and are allowed to flow over the beds of the catalyst mass, preferably in vertical reactors with a downward flow of the reactants through that mass. From a commercial standpoint the continuous process lends itself more readily to economical operation and is to be preferred over the conventional batch-type operation. It is to be distinctly understood, however, that the particular mode of operation of the invention is not limited in any respect but that any of the conventional forms of apparatus used in polymerization or analogous alkylation processes may be employed with highly satisfactory results.

Pressures ranging from about lb./sq. in. to about 200 lbs./sq. in. gauge may be used, but in general, it may be said that the higher pressures. coupled with the higher temperatures, are not conducive to the formation of alkylation products. Atmospheric pressures have been found to give good results, as well as moderately eleslightly below and under substantially atmos- I pheric pressure, it is advantageous to introduce a the reactants into the catalyst chamber at the vated pressures in the neighborhood of about 50 lbs/sq. in. gauge. Temperatures of between about 10 F. and about 500 F. have been used, but it is preferred to operate within a temperature range between about and about 80 F. Temperatures much below 10 F. are distinctly detrimental to the production of the desired products; that is, those products boiling within the motor fuel range. Thus, the use of a temperature around 80 F. would produce a heavy, viscous liquid wholly unsaturated in character and of little value so far as the production of motor fuels from olefins and isoparaflins is concerned.

Reaction'times of between about and about 7 hours have been found to be desirable, but it is preferred when operating to secure optimum yields of saturated products to allow a contact time of between about 2 /2 and about 5 hours. This allows for a substantially complete alkylation of the paraffinic constituents and, at the same time, results in the production of relatively little of the higher boiling constituents.

The amount of alkyl halide added ranges from about 1% to about 15%, depending upon the specific alkyl radical and the specific halide present. Thus, in the case where a propyl radical is present, less weight per cent of the compound is required to accomplish the same results than in the case where a butyl radical was employed. The same also holds true where the halide portion of the added compound is of less molecular weight than another halide of greater weight,

. for example, chloride would require a less weight per cent to be added than would bromide and yet, the same results could be accomplished so far as qualitative yields are concerned. In cases where tertiary butyl chloride is used as the alkyl halide, it is preferred to add between about 3 and about 6.5% by weight based on the total amount of feed stock used in the run.

Experimental evidence points to the theory that the mechanism of.the alkylation reaction involves the intermediate formation of polymers or copolymers by the mono-olefins followed by the degradation of these higher polymers and copolymers into an active or nascent state which permits their reaction with the paraflins present. The same mechanism appears to hold true where the reaction occurs between a preformed polymer or copolymer and a parailln. While the theory of the invention appears to be as described, it is to be distinctly understood that the invention is not limited to any theory of operation and is restricted only insofar as indicated by the appended claims.

No specially designed apparatus is necessary for the successful carrying out of the invention. Conventional apparatus now customarily used in effecting solid catalytic polymerizations is quite suitable. In the case of effecting alkylations under pressures of 1800- to 3000 lbs;/sq. in, it has bottom and remove the reacted mixture from the top of the reactor. The fractionation of the resultant products is accomplished in conventional fractionating towers. Any excess or unreacted reactants may be recycled to the catalytic reactor after first being mixed with the fresh feed just prior to its introduction into the catalyst chamber. If desired, 'the recycled reactants may be subjected to a dehydrogenation treatment prior to their mixing with the fresh feed. It is apparent that the process and apparatus may be readily adapted to the carrying out of a continuous operation. Such a type of process and apparatus is familiar to those working in the art and it is to be understood that conventional and/or minor variations therefrom may be made without departing "from within the spirit or scope of the present invention.

For illustrative purposes and not with the intention of restricting the invention thereto, there is shown in the accompanying drawing a diagrammatic illustration or flow sheet representing one specific process adapted to carrying out the invention. The process may be adapted to the use of liquid, gaseous, or solid catalysts as the exigencies of each particular case might require. It is to be distinctly understood, however, that theinvention in its broader aspects is not restricted to any particular type of apparatus or been found to be advantageous to introduce the to any particular fiow plan, but that the flow plan hereinafter described is only intended to aid in a further understanding of applicants invention.

Referring to the drawing, the oleflns and paraflins to be subjected to alkylation are introduced into the system through charging line I by means of pump 2. The olefinic-paraflinic hydrocarbon mixture may then be passed through pipes 8, 20, i3 and I5 controlled by valves I and 14 directly into alkylation reactor it which is filled with the desired catalyst and provided with suitable heating or cooling jackets (not shown), "or, if it is desired to polymerize a portion of the oleflnic content of the feed prior to the alkylation' reaction, valve 1 may be closed and the. feed passed through line 4 controlled by valve 5 into any suitable conventional polymerization reactor such as that represented by reactor 8. The olefinic portion of the feed is converted into polymers thereof while the paraillnic portion remains un changed. The resultant mixture of polymers and paraflins exits through pipe l0 controlled by valve 9. Valve 18 is closed and the polymerized mixture enters the alkylation zone through lines l0,

actants intothe alkylation reactor so that they will flow through the catalyst in the opposite direction from that described above. In such a case, reactants not passing through polymerization zone 8 are flowed'through pipe 5 controlled by valve 1 into pipes ll, H, II and II, valves l2 and II being open and valves I, 3, II and 23 being closed. The reaction mixture discharged from the alkylation zone ll passes by means of lines II, 21 and ll into stabilizer 3|. If it is desirable to first subject the olennic-paratiinic hydrocarbon mixture to a preliminary polymerization treatment, valves I, i3, is and 2' remain closed and valves I, I, I3 and 23 are opened so that the flow is through pipes 4, l0, l1 and I3 into the alkylation reactor II.

It is sometimes found advantageous to allow the ultimately complete alkylation reaction to proceed in small increments of the total final conversion and to recycle the reactants continuously through the alkylation zone It through the circuit of pipes II, l3, II, ll, 33, 33 and 32 provided with pump 31. Pump 33 is by-passed by allowing the how through pipe 34 and valve 35.

It is contemplated to so recycle whether the reactants are contacted with the alkylation catalyst downfiow or upflow, pump 33 being provided tor the reversed direction of flow from that above indicated. For downflow operation pump 31 is by-passed by allowing the flow through pipe 33 and valve 31. A portion of the reacted mixture so recycled is withdrawn either intermittently or continuously, the rate of withdrawal being adjusted to insure adequate time for substantial completion of' the alkylation.

Any suitable method of dispersing the reactsure the removal of normally gaseous hydrocarbons from the normally liquid hydrocarbons. The gases comprising paraiiins, and at times some oleflns, leave the stabilizer by means of pipe 5! controlled by valve 53. If desired, these gases coming from the stabilizer may be reintro duced directly into the fresh feed pipe 3 by closing valve I3 and opening valve 55 so that the gases are conducted to pipe 6 by means of pipe 54, or the gases may be bled from the system through pipe" and valve 83, valves 53 and I being closed. A compressor unit (not shown) is inserted in line II to liquefy the gases prior to their introduction into feed line 3. It is preferable, however, to close valve 5! and open valve "so that these gases which are predominantly paramnic in character are passed to a dehydrogenation step I of any suitable conventional design, wherein the gaseous parafiins are converted into gaseous oleiins either in whole or in part, the gases are liquefied, hydrogen, methane, C: and 0; fractions are removed, and the remaining gases leaving the dehydrogenation step 53 by pipe I! are pumped by means of pump 53 into the fresh feed line I.

The normally liquid products leaving the bottom of stabilizer 30 by means of pipe 3i may be conducted directly to the gasoline still ll through lines 40 and 41 by opening valve 33 and closing valve 33, conducted directly back to the alkylation unit l3 by means of pipe 32 by closing valves 33, 3! and 3! and opening valve 34, thereby eflecting further conversion before final treatment, or conducted by means of pipe 42, closing valves 33 and 34 and opening valve 30, to an oleiin extraction unit 43 wherein by any suitable conventional treatment, such as treatment with a solvent, for example, sulphur dioxide, any normally liquid oleilnic polymers that might be present are removed. Free olefins from this unit may be removed to storage (not shown) through line 33 controlled 'by valve II or they may be directly returned by means of pipe 43,

33 and 33 to the alkylation unit II. It is to be understood that when the bottoms from stabilizer 30 are conducted back to the alkylation unit It, only a portion of these bottoms are so recycled at any one time, the remainder of the bottoms being treated according to any of the alternative methods above suggested.

The liquid paramnic fraction is conveyed to gasoline still 43 by means of pipes 45 and 41 upon opening valve 46.

Gasoline still v43 is maintained at suitable controlled temperatures such that a desired gasoline fraction is removed to storage through pipe 49 and the heavier fraction removed through line 50 by opening valve II.

It is convenient when .using a solid catalyst to have a plurality of reactors, such as alkylation reactor ll, arranged in parallel so that while two or more are being actively used a similar number may be subjected to a regeneration process. Such a procedure thereby provides for intermittent reactivation of solid catalysts without interruption of the continuous process.

Example 1 A feed stock containing 10.5% of isobutylene, 0.4% normal butylene and 81.9% of isobutane in an amount of 14 grams of catalyst per grams of feed was subjected to a 10% U30. impregnated on silica gel catalyst at a pressure of 50 lbs/sq. in. gauge and a temperature of about 77 F. in a batch operation for a few hours. A product was obtained in an amount of about 73% yield based upon the total unsaturates in the feed stock, had a bromine number of about 100, and contained 25% paraflinic hydrocarbons. The product consisted of 70% by weight of a C: fraction and 30% by weight of a Ca and heavier fraction, and had a final boiling point of 397 F.

Example 2 nated on activated alumina in an amount corresponding to 11 grams of catalyst per 100 grams of feed stock for 5 hours at atmospheric pressure and at a temperature of about 15 F. The product was obtained in a yield of about 70% based upon the isobutylene content of the feed stock, and had a bromine number of 65. It was composed of 2% by weight of a Ca fraction, 10% of a Cs fraction, 30% of a C1 fraction, 20% of a C; fraction and 38% of a Ca and heavier fraction.

In a similar experiment conducted under substantially identical conditions of operation, but wherein no tertiary butyl chloride was added to the feed stock, no reaction occurred, hence it may be concluded that the tertiary] butyl chloride quite actively promotes the latent ability of uranium catalysts in influencing their alkylation activities. Apparently, when an activated alumina is used as the carrier for the uranium oxide catalyst, the addition of an alkyl halide is required in order for the uranium oxide to efiectuate an alkylation reaction. It will be noted that in the case of Example 1, a catalyst of uranium oxide on silica gel promotes alkylation without the presence of an alkyl halide, whereas in the case of uranium oxide on activated alumina, apparently no alkylation resulted unless an alkyl halide was present.

Example 3 A feed stock composed of 10.2% isobutylene.

1.6% normal butylene and 88.2% o! isobutane in an amount of 11.8 grams of catalyst per 100 grams of feed was contacted with a uranium oxide impregnated on Super Filtrol for 5 hours with vigorous agitation at atmospheric pressure and at a temperature of about F. A product was obtained which had a bromine number oi! 65 and contained 60% by weight of saturated hydrocarbons. The product had an A. P. I. gravity of Example 4 Using the same catalyst as in the preceding example, and contacting the same continuously with a feed stock composed of 9.4% isobutylene, 1.8% normal butylene and 88.8% isobutane at a temperature of about 404? F. and a pressure of 2000 lbs./sq. in. gauge at a continuous throughput'ot about 3.6 volumes of feed/volume of catalyst/hour, resulting in a yield of 97% based upon the isobutylene content of the feed stock. The product had a bromine number at 150 and contained no parafllnic hydrocarbons. The product was composed of 60% by weight 01 'a Ca traction and 40% by weight of a Ca and heavier fraction, and illustrates an example wherein an uranium oxide catalyst effectively promoted a polymeriza-- tion reaction rather than an alkylation reaction. The olefin I reduction during the reaction amounted to 88%.

The above examples are intended to be but illustrative of the concept oi. the invention and they are not to be considered as limiting in any way the scope of the invention. I

The nature and objects of the present.invenof normally gaseous monomeric mono-oleflns,

dimers, trimers, tetramers, andhigher polymers thereof, 00-, inter-, and cross-dimers, trimers, tetramers and higher analogous polymers thereof. in the presence of at least one binary compound of uranium under alkylation reaction conditions.

5. A process as in claim 4 wherein the uranium compound is deposited on a clay in the presence of a lower alkyl halide.

6. A process as in claim 4 wherein the uranium compound is deposited on silica gel.

7. A process as in claim 4 wherein uranium compound is deposited on activated alumina. and

wherein the feed stock contains tertiary butyl chloride. I I

8. A process as in claim 4 wherein the uranium compound is deposited on an acid-treated bentonitic clay and the reaction is carried out in the presence 01' between about 1% and about 15% acyclic hydrocarbons boiling chiefly in the gaso-.

1 line range which comprises reacting a mixture tion having been thus fully described what is is carried out continuously under at least sur ficient pressure to maintain the reactants in the liquid phase. v

4. A process for the production of substanunder F9 7 containing isobutylene and isobutane in the presence of an oxide of uranium under alkylation reaction conditions.

11. A process which comprises reacting a mixture containing about 10.5% of isobutylene'and about 89.5% of isobutane at about lbs/sq. in. gauge at a temperature of about 77 F. in the priasence 01' a 10% UaOc impregnated on silica ge 12. A process which comprises reacting a mix- 5 about 3.6 volumes oi! teed/volume oi! cata- 3. A process as in claim 1 wherein the process.

lyst/hour in the presence or a catalyst composed 1 of a 19% 'UaOa impregnated on an acid-treated bentonitic clay.

. ELDON E. STAHI'IY.

ERWIN M. I-IA'ITOZ.

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