US2827500A - Integrated hydration and alkylation of gaseous olefins - Google Patents

Description

United States INTEGRATED HYDRATION AND ALKYLATEON OF GASEOUS OLEFINS Walter P. Bloecher, Jr., Cranford, and David W. Young,

Westfield, N. L, assignors to Esso Research and Engineering Company, a corporation of Delaware Application October 14, 1954, Serial No. 462,201

6 Claims. (Cl. 260-641) This invention relates to the conversion of gaseous olefins to a liquid fuel of balanced volatility and superior anti-knock characteristics. More specifically, it relates to a flexible combination process wherein a C C olefin-containing light hydrocarbon feed is catalytically converted to a high octane liquid motor fuel in two stages, first being partially hydrated to produce an oxygenated motor fuel while the unconverted remainder is alkylated in a subsequent stage to produce gasolinerange hydrocarbons. It also relates to the fuel compositions produced in the process.

In the blending of motor gasoline the quantity of high volatility components which can be included is limited by specifications which are based on Reid vapor pressure and the percentage distilling below 158 F. If these specifications are exceeded, the undue front-end volatility of the gasoline blend tends to cause vapor lock in the combustion engine. Consequently a surplus of propylene, butanes and butylenes is usually available at most refineries and must be either disposed of in lowpriced products such as fuel gas or must be converted into a less volatile gasoline blending stock. Such upgrading has been heretofore accomplished mostly by cata lytic polymerization of the C -C olefins. However, this has not constituted a fully satisfactory use of available light ends since such polymerization makes no use of saturates and the resulting polymer possesses only a moderately good motor octane rating whereas with the advent of automatic transmissions motor octane specifications have been becoming increasingly critical. Therefore, a real need has developed for a refining process capable of producing a gasoline blend having a high motor octane rating while making economical use of available light ends.

It is well known that olefins such as propylene can be directly hydrated in the presence of suitable catalysts such as phosphoric or sulfuric acid or tungstic oxide, to produce oxygenated products such as alcohol, acetone and ether, all of which greatly improve the motor octane rating of gasoline blends when added thereto. However, such addition also results in an increased volatility of the gasoline so that compensating amounts of inexpensive butanes and other light naphtha constituents must be left out of the blend. Consequently, the addition of the oxygenated hydration products may result in a substantial increase in cost of the blended gasoline product and further aggravates, rather than relieving the problem of properly utilizing the surplus light ends. This light ends surplus may become particularly troublesome 2,8215% Patented Mar. 18, 1958 in the summertime when a relatively less volatile gasoline is required. Furthermore, the hydration of propylene is in itself rather diflicult to accomplish and accordingly requires feeds having as high a concentration of the olefin as possible. But since conversion tends to be rather low and so usually makes stage-wise conversion of unreacted feed imperative, the latter must be purified or separated from the hydration products before it is further hydrated.

It is also known that a premium grade gasoline component can be obtained by alkylation in which olefins such as propylene, butenes or pentenes are combined with isoparaflins such as isobutane or isopentane. Such alkylation can be done thermally at high temperatures and very high pressures, but is preferably done at low temperatures in the presence of catalysts such as concentrated sulfuric acid, hydrofluoric acid, aluminum chloride or boron trifiuoride. Such catalytic alkylation proceeds quite readily and, as long as a suflicient excess of the C 01' .C isoparaflin is present, results in substantially complete conversion of the olefinic feed constituents into valuable C to C branched chain paraffins of high anti-knock value and relatively low volatility.

Heretofore, however, when a refinery was required to rely upon such alkylation to any great extent for the purpose of raising the octane level of gasoline, a critical shortage of necessary pressurizing stocks tended to develop. This resulted from the fact that the alkylate product had such low volatility that it had to be supplemented by substantial amounts of butanes to give satisfactory start-up characteristics, but the alkylation itself consumed a large proportion of isobutane from the light ends pool normally available for pressurizing. Consequently, the adoption of alkylation in the production of motor fuel has not always been economically attractive, despite its intrinsic merits. On the contrary, because of the excess supply of olefins with respect to available butanes, notably isobutane, alkylation has been heretofore limited largely to the most desirable olefins, namely the butenes, although C and C oiefins can also be ailcylated to give a superior gasoline constituent. Moreover, even the alkylation of butenes has often resulted in upsetting the volatility distribution of a given gasoline pool. Here again, the fact that the gasoline product is normally required to meet substantially different volatility specifications in the summer than in the winter has represented an additional complication.

It is the main object of the present invention to provide a flexible process for the conversion of light ends, and especially propylene, to a high quality blending agent, the volatility of which can be readily varied to meet operating needs. Another object is to convert C -C hydrocarbons to compounds suitable for increasing the motor octane rating of gasoline blends without upsetting their volatility requirements, particularly in the blending of motor fuels having research octane num bers of 96 to 100 or higher and ASTM motor octane numbers in the range of about 83 to 100, and especially those having motor octane numbers between about 85 and or higher. A more specific object is to hydrate and alkylate a propylene feed substantially completely in an integrated process whereby liquid fuels having a superior octane rating and balanced volatility are produced, with a minimum of recycling or handling of inert diluents. A still further object is to hydrate gaseous olefins in a non-corrosive system to produce oxygenated products suitable as motor fuels, and to achieve substantially complete utilization of the feed with a minimum of recompression and purification. Still another object is to provide blending stocks suitable for raising the volatility and octane characteristics of other streams which may include virgin naphtha, thermally or catalytically cracked naphtha, hydroforniate, and so forth. These and other objects as well as the general nature and operation of the invention,'will become more clearly apparent from the subsequent descriptionand accompanying drawing.

It has now been discovered that light olefins can be essentially completely converted to valuable gasolinerange constituents of b'alanced, predetermined volatility in a surprisingly efiective manner. This is done by first passing-the olefin-rich feed through a catalytic hydration step and then completing the conversionlby alkyla tion of the unconverted olefins. Furthermore, a combination process particularly adapted to optimum ntilizaa tion of propylene and C hydrocarbons will include direct hydration of propylene, propylene/butylene alkylation, and polymerization of butylenes. According to the present invention these individual processes are combined and integrated so' as to complement each other in maintaining a flexible and unusually effective balance among the several reactants, especially propylene, butylenes, and

isobutane, and in maximizing conversion of propylene.

Unless otherwise indicated, all ratios and percentages stated in the subsequent description and claims are on a weight basis. a I

Useful as hydration feeds in the present process are refinery streams containing about 30 to 100 mole percent of a C and/or C olefin,'which may further con tain minor amounts of ethylene and higher olefins, usually in'addition to at least 5 mole percent of inert gases such as hydrogen, methane, ethane, propane, bu-

tanes, nitrogen, carbon dioxide, etc. The preferred olefinic feedto the hydration stage is a C hydrocarbon cut consisting essentially of about 70 to 95 mole percent propylene and correspondingly 30 to 5 mole percent propane, that is, a cut containing about 2.3 to 9 moles of propylene per 'mole of propane. Another likely feed may be a C -C cut containing a mixture of propylene and butylenes together with propane and butanes, and usually also some ethylene. preferably first purified to remove sulfur compounds,

notably hydrogen sulfide, e. g. by washing with diethanol amineor a similar organic base. Alkaline compounds and heavy oils may. also desirably .be removed from the feed in any known manner and such purification steps do not as such fo'rrn a part ofthe present invention.

'In the direct hydration step' the OICfiH-I'lCh 'fCBd is mixed with 0.2 to 5 moles, preferably lj to 2 moles, ofwate'r per mole of olefin. The mixture is then passed over any suitable solid or liquid hydration catalyst, preferably of the 'low acid, non-corrosive type suitable for use in regular steel equipment.

containing about 40% of phosphoric acid baked into a solid support such as kiesel guhr, clay, silica gel, alumina, titania, char coal, coke, activated carbon, and the like..

In most cases the feed isv 7 Accordingly, the; catalyst may be of the so-called modified UQP type condensate and steam for removing the heat of reaction.

Hydration conditions may include pressures of about 500 to 5000 p. s. i. g., preferably 800 to 1500 p. s. i. g., and temperatures of about 120 to 300 C., preferably 200 to 235 C. Above about 235 C. the selectivity to hydrated products may decrease fairly markedly at the expense of polymer formation. The hydrocarbon feed is usually present in the reaction zone as a supercritical mixture. Conversion varies essentially indirect proportion to pressure. The reaction is carried out with space velocities of 0.5 to 5 volumes of liquid olefin feed per volume of reactor per hour, velocities of 1 to 3 v./v./hr. being preferred. At these velocities about to 70%, e. g. 30% of the olefin present in the feed can be readily converted to a liquid mixture of alcohol, ether, some liquid polymer of gasoline boiling rangaansusuan also some ketone. -Suchamixture will have a research octane number of about 110 to 112 to .116 unleaded, 'a-

motor octane number of about 93, a specific gravity of about 0.71 to 0.75 and an atmospheric boiling range essentially between about 50 and 95 C., though it may uable, clean burning fuel which is suitable for use 'in Other suitable catalysts include adipic, maleicor simi-f lar organic dibasic acids, adsorbent silica-aluminia gels of the type commonly used for catalytic cracking, silver sulfate, as well as copper sulfate or phosphate or copper pyrophosphate of the type heretofore used-in poly-men .Another suitable catalyst is reduced tungsten zation.;

pentoxide... v s. p 7 The hydration reactor may be-a'heat-exchang ertype of vessel consisting of catalyst-filled tubes'jacketed by reactor. I

separated from the. unconverted feed by cooling the hydration Zone. efiluent so as to form a waterflayer and either aviation or motor gasolines. Such a hydration product, on an anhydrous basis, will normally contain about 55 to 96 volume percent of alcohol, 3 to 35 volume percent ether, 0 10 V10 volume percent acetone, and, about 1 to 25' volume percent polymer.

The unconverted hydrocarbons withdrawn from the hydration step will contain about 15 to 70 mole percent and preferably only about 20 to 50 mole percent. of

propylene or C .C olefin. The reaction mixture from; t l the hydration stage is desirably first passed through a frac tionating column Where water and thevaluable hydrated products are Withdrawn as a liquid bottoms fraction and only the unconverted feed mixture containing primarily the olefin diluted with paraffins or other inert gases is 7 taken overhead and passedto the alkylation stage unit. The previously mentioned fractionating column or stabilizer is operated an suitable pressure, e. g. 200 to 400 p. s. i. g., and the .olefinic overhead stream is condensed to permit its being pumped to the second-stage Alternatively, the hydrated products can be a hydrocarbon layer separable therefrom.

7 In the alkylationstep the unconverted .olefin'is combinedwithan isoparaflin-containing C, or C streamsuchas abutane-butylenes st ream coming from, a C catalytic polymerization plantand normally containing 50 to isobutane. Thecombined a lkylation feed is of such com position that the. i'soparafiin contained therein, e. g. isobutane, is sufiicient toalkylate the olefin, after incurring any processing losses. As 'a minimum, for instance, the

feed to the alkylation plantshould contain 1.6 volumes,

of isobutane per volume of propylene, or 1.2 volumes of isobutane per volume of butylenes. An isoparaffin/olefin ratio in the total reactor feed of about 3/ 1 to 10/1 is desirable, a ratio. of about 8/1 being preferred. Considerably higher. isopa'rafiin/olefin ratios are normally maintained in'the. reaction zone proper, ratios of about 150/1 to 1000/ 1, e. g. 2507.1, being suitable. The alkylation may be catalyzed in a conventional manner, e. g..

by mixing with sulfuric acid of about 88 to 98% strength.

Such an alkylation maybe. conducted in the acid phase of the resulting oil-acid emulsion, maintained at about 30 to 70? F by refrigeration. As is. otherwise well known, the .heat of reaction can be removed from an emulsion recycle, the volume of which is large relative to the fresh feed. For instance, an emulsion/olefin volume ratio of 60/1 to 100/1 is advisable. Recycling of the emulsion also provides the energy required for mix= ing the contents of the reactor to maintain the emulsion and to eliminate localized concentrations of olefin. The reactor pressure is sufficient to maintain a liquid phase, e. g. 100 to 200 p. s. i. g. The emulsion will consist of 20 to 60% acid by volume, and operations will be maintained so that 40 to 70% by volume of the oil phase will be isoparaffin, the remainder being alkylate, normal parafiins and olefins. Acid strength in the reactor is maintained by fortifying it with 98% acid and withdrawing a corresponding amount of weaker acid from the process.

A portion of the emulsion recycle may be diverted to an acid settler. The oil phase from this vessel is preferably caustic washed and fed to a tower which will remove and purge any residual light hydrocarbons. Since the conversion of olefin in the alkylation plant is essentially 100%, the purge will normally be free of olefin. The bottoms, consisting of isoparafi'in, normal paraifin and alkylate are fractionated further. The isoparaffin is split out in a deisobutanizer column and recycled to the alkylation reactor while normal butane is taken overhead in a debutanizer tower, mixed with any by-passed C streams, and sent to gasoline blending for vapor pressure control. Since alkylate and normal butane are remixed in the final gasoline blend, the debutanizer can be bypassed entirely if the combined product happens to meet volatility specifications for motor fuel. The alkylate bottoms from the debutanizer tower may then be rerun to a 330 F. endpoint overhead suitable for aviation gasoline, a 430 F. endpoint sidestream for motor gasoline, and a +430 F. bottoms for heating oil.

Of course, instead of using the sulfuric acid emulsion system described, the alkylation may be conducted in a variety of other ways without departing from the present invention. For instance, gaseous catalyst such as boron trifluoride, other liquid catalyst such as hydrogen fluoride, or a solid catalyst such as aluminum chloride may alternatively be used in suitably modified alkylation processes which are otherwise well known.

In accordance with the preferred embodiment of the invention the process also contains a catalytic polymerization step for maximum versatility. Such polymerization may be of the UOP-type using a tubular reactor packed with a catalyst consisting of kieselguhr impregnated with phosphoric acid. Alternatively, California-type polymerization may be used in which phosphoric acid on quartz chips is placed in a tower-like vessel cooled by recycle quench streams. Both types of plant operate at about 300 to 450 F. and at elevated pressure, e. g. 1000 p. s. i. g. The feed to this unit is an olefinic stream in the C C hydrocarbon range, e. g. a refinery C stream containing 20 to 60% butylenes with 20 to 50% isobutane, preferably washed with caustic soda and water. Propylene may also be fed to the polymerization unit, especially in the summer time when a motor fuel of relatively low volatility is required. The percentage of olefins converted in the polymerization stage can be varied from to 95% either by varying reactor conditions or by bypassing the reactor. Olefin polymer, unreacted olefin, and saturated hydrocarbons can then be separated in a suitable fractionation tower, e. g. at 150 to 200 p. s. i. g. pressure, from which the polymer is removed as bottoms. The overhead may then be sent to gasoline blending and to supply the isoparafiin to the alkylation stage as required.

A specific operation illustrative of the present invention will now be described with reference to the schematic flow plan shown in Figures 1 and lA of the accompanying drawing. In the illustrated embodiment a light olefin feed is hydrated and alkylated in sequence, in combination with an olefin polymerization step which further helps in balancing product volatility and thus further increases the flexibility of the process.

Referring to the drawing, the equipment shown is subdivided into three principal sections: a catalytic hydration plant'and a catalytic polymerization plant, both of which are shown in Figure l, and a connected alkylation plant shown in Figure l-A. Two hydrocarbon streams, both being obtained from a C C cut from a catalytic cracking plant, are fed to this combination of units. One stream is a C stream consisting essentially of about 65 mole percent of propylene and 35 mole percent of propane, desulfurized by scrubbing with diethanolamine; and the other is a caustic and water washed 0.; stream consisting essentially of about 48.5 mole percent isobutane, 8 mole percent normal butane, 16 mole percent isobutylene and 27.5 mole percent of normal butylenes. The entire C C cut from which these two feeds were obtained contained about 42.5 mole percent of C hydrocarbons and 57.5 mole percent of the C hydrocarbons.

Referring to Figure l, the C stream is liquefied and fed to the hydration plant via line 1 to depropylenizer tower 2. This tower is operated at 300 p. s. i. g. and splits the feed into an olefin concentrate consisting essentially of mole percent propylene and 10 mole percent propane, and a bottoms product consisting essentially of 90 mole percent propane and 10 mole percent propylene. The bottoms stream is withdrawn from the system via line 3 and can be used as fuel or finished to commercial liquefied petroleum gas. The propylene concentrate is removed from tower 2 via overhead line 4, condensed and mixed with 1.5 moles of water of hydration per mole of propylene. This water is introduced via line 7. The liquid mixture of olenfinic feed and water is passed through line 9 into hydration reactor 10. This reactor is a heat-exchange type vessel as previously described, the vertical tubes of which are packed with a pelletized hydration catalyst consisting essentially of reduced tungsten pentoxide prepared as described in British Patent No. 622,937 (1949). The reactor is kept at a temperature of about 225 C., the heat of reaction being removed by cooling water which is circulated through and evaporated in the cooling jacket which surrounds the reactor tubes. The reaction pressure is maintained at about 1700 p. s. i. g. The hydrocarbon feed is passed into tower 10 at a space velocity corresponding to about 0.5 volume of cold liquid feed per reactor volume per hour. A conversion of about 40% of the olefin feed is obtained, yielding a mixture of isopropanol, diisopropyl ether, liquid polymer of gasoline boiling range, and a small quantity of acetone.

The wet crude reaction product is withdrawn from the hydration zone through line 11, throttled through a valve 12 to a pressure of about 300 p. s. i. g. and fractionated at that pressure in stabilizer tower 15. Here unreacted propylene and propane are taken as a liquid overhead stream 16 while the hydrated olefin and unreacted water are taken as bottoms through line 19.

Tie-ins are provided between stabilizer overhead line 15 and depropylenizer feed line 1 and reactor feed line 4. This permits recycling unconverted propylene from line 16 through line 17 back to hydration reactor 10, or conversely, if more propylene is available than is required for hydration, surplus olefin may be diverted around reactor 10 from line 1 via line 17, or from line 4 via lines 14 and 17. Any unhydrated propylene finally leaves the hydration plant as stabilizer overhead via line 16 and is fed to the alkylation plant as hereafter described.

The stabilizer bottoms 19, consisting of water and hydrated product, is fed to finishing facilities for removal of water. This may be accomplished by a series of two or more azeotropic distillations conducted at different pressures so as to break the azeotrope formed in the preceding distillation stage. Alternately, as illustrated in the drawing, water may be removed by azeotropic distillation in dewatering tower 20 followed by caustic treatment.

Tower 20 separates the crude hydration product into water bottoms and an azeotropic distillate containing about-91%- organic liquid and- 9% water. Thenvater bottoms separated in tower -20,-is' sent tojthe sewer via line 22 while the az eotropicdistillatefil is made essentially anhydrous by scrubbing in, causticcontactor 25.w ith a 50% aqueous caustic .soIution introducedthrou'gh line 26. Dilute caustic solution .is withdrawn-.yia linef28.

The final product is-taken as an overhead stream 31 from steam evaporator 30 to remove, any residual caustic and will contain 3% or -less water1 by volume. ffFoninstanee, a; typical dry- 'productmay b'oil between about 5 and,

92 C; at 760--mm.* Hg and'consist' essentially of "85% isopropyl alcohol, 5'%* diisopropyl emery-2% acetone, 5%: polymer and 3 water;all on a-volume basisig This com For instance, during winter operations -when high-vola-' tility is desired, thepropylene'may berecycled through the hydration plantto extinction, resulting in a hydrated product yield-of about 82%. -In-the summer time when gasoline volatility isto'be kept fairly-low, the'hydration plant may best'be operated on aonce-through basis, re-- sulting in'a hydrated-product yield of about 24% based on propylene feed. a a g If desired, vthehydration-product can be used directly as a motor fuel, butpreferablyit will be blended with various hydrocarbon base stocks boiling inthe gasoline range. Such base stocks,"it is =well known, maycontain virgin naphtha, thermally or catalytically cracked gasoline, reformed orshydroformed naphtha, polymer. gasoline, hydrocodimer, or..variousmixtures thereof. Furthermore,.in accordance with the present invention itis particularly advantageous to balance the-increased volatility dueto'the. hydration product by blending in a suitable amount of alkylate .producedin alater described part of the present process. Typically, the gasoline base stocks may:have: a clear research octane rating of about 85 tov 103, usually between about-85 and 90 in the case of motor fuel, and a motor octane rating (leaded) ,which may range from about85 in summer to 100 in Winter. Of course, usual anti-knock agents,=e. g. 1 to 5' cc. of tetraethyl lead per gallon, other additives such as'lauryl p-aminophenol, 4-methyl-2,6-di-tert-butyl phenol or other anti-oxidants, gum-inhibiting agents, phosphorus containing surface ignitionlinhibitors such as tricresylphosphate or chloropropyl,thionophosphate, and other conventional materialsmay: also be added. Ofecourse, instead. of'

blendingthe hydration product into gasoline, it .canalso beaddedto diesel fuel; e. g. to improve itscoldstarting properties.

The other main feed tothe process is. a C stream from a catalytic cracking, unit. This stream maycontain, as an example, 55% butylenes, 36% isobutane and 9% .normal butane. stream is fed via line 41 to a tubular UOP type polymerization reactor 40 filled with a catalyst consisting essentially of kieselguhr impregnated with phosphoric acid. This reactor is operated at about 1000 p.;s. i. g. and 380 F. A butylene conversion of about .70 %;;isuobtainedin reactor 40. However, if desired, a'lower overall conversion of butylenes can be obtained by diverting butylenes from line 41 around reactor 40 via by-passline After caustic and water washing this C 42. Of course, lower or higher butylenes conversion can 7 a C to 430 F. butylene polymer is removed as bottoms via line 46. Butylenes and butanesare taken as an overheadproduct 47 and, after mixing With,by-passedreactor feed 42, if any, sent to gasoline blending and the alkylation plant as required. For instance, referring tov Eigurej 1;- -A, an'increased am'ountoffthe' C, out can be sent via line 481 gasoline blending when 'C h'ydrocarbons are in relatively, short supply with respecttothe vaponpressure requirements otthe gasoline product pool; Conversely;

when' 'Cghydrocarbons are in longsupplyaall or most of thefC cut from the polymer plant issent' through line 49 tothealkylation, plant andlittle or noneis. withdrawn throughline 48. '"In such cases any need for'raisingthe vblatilityofthegasolinepool'carr be satisfied by; using the normal butane separated inthe alkylationplantas' hereafter; described.

Again referring'to Figure the feed tothe alkylation' reactor may comprisethe; butane-butylenes stream;

49 from thepolymerization plant, ,the; propylene-rich stream 16' fromthe-hydrationplant" and a ,stream .57

of-9 8%- sulfuric acid-which -serves as a catalyst. For example, in-the summerthe C stream 49 may; contain about' 82.7 vol.-percent isobutane,- 13.7 1 vol. percent nbutane and 3.6-vohpercent-butylenes, and C stream- 16 may contain about 86.3 vol.- percent propylene and 1317 The combined feed inline 61 is volume of'C; hydrocarbons, or specifically about 0.78/1- for the particular example-given. On' the other hand, nopropylenewill normally betsentto alkylation in winter.

Consequently, the: alkylation feed will consist of'the C stream 49v.which thenzmay be somewhat leaner in -isobutane, e. g.', it may contain- 50 vol. percent isobutane, 8.4 .vol. percent n-butane, and 41.6%; butylenes. Freshacidis addedto the hydrocarbon feed attaboutthe rate at whichitis. consumed, that. is, about 1 to 1.5: gals/gala The mixture is maintained inreactor in liquid' olefin. phaselatebolutl 35".. F.. anda pressure .of' 150.p..-'s. ieg. Heat. of reaction .is removed, by refrigeration from.emulsion recycle,line,63 .which,passes through heat exchanger 62 at arate Oi about 100 volumes of emulsion per volume; of olefin feed. Theemulsion consists of. about 50%. acid' by volume. The, oil phase of the emulsioncontains about 55 iso but ane by volume.

A fraction equal to about 3 to Spercent ofthe emu1-. sion is diverted from recyc1elinel63 vialine 64 to acid settler 65. Here ;the spent. acid. layer is removed via line 67, while the oilphaseis, removed via-line 68 and washed in scrubber 69-with strongcaustic introduced via line66. 1 After settling in tank 70 the spent caustic is discarded via .line, 71 while, thescrubbed oil phase is sent viai rline 72 togstabilizertower 75. There any residual C hydrocarbon, that is, essentially pure propane, is removed and sent via:line 76 for .use. in liquefied petroleumgas. ,The' bottoms from depropanizer tower 75, are pumped jvia .'line 78. to deisobutanizer tower .80 where;isobutane;;isysplit out and, recycled. vialine 81zto alkylation, reactor; 60. The bottoms ,frorn tower are pumped via line 83 to ,debutanizer towera85awhere-nor-.

mal-butane issplitout andsent :via line 86 to gasoline blending for vaporpressure control. Where necessary, someofi this normal butane may also be. isomerized to increase the supply of isobutane required in the alkyla tion. The alkylate bottoms stream 87 from the de-' butanizer -may then, be rerunin tower'90. .There a light alkylatehaving a 330" F. endpoint suitable for aviation gasolinehisproduced asanoverhead stream 91, a heavy alkylatehaving a 430,F. endpoint suitable for motor gasoline is'removed vialine 92,. and. alkylate bottoms. suitable :for heating'oil are removed-via line 93. ,Of course, since alkylateuandnormal butanerare. -eventually remixed inthefinalg soline blen eua kyl e debu anizer 85 can be partially or entirely bypassed via line 84, if

line will have a clear research octane number of about 7 92 to 93 and a motor octance number of about 90.

EXAMPLE The products of the present invention can be used for formulating various gasoline blends which will meet the customary voatility specifications with respect to both Reid vapor pressure and percent distilling at 158 F. Thus, Tables I and II illustrate winterand summergrade gasolines, respectively, formulated by blending all ing a Wide variety of specifications.

of the various products of the novel combination process.

Table I WINTER-GRADE GASOLINE Vol/100 vol. Composition Total 03-04 of Blend,

Feed Vol. Percent 0 Hydration Product 25. 3 35. 6

C Alkylate 0 0 Ca Polymer.- 0 0 O4 Alky1ate.. 38.1 53. 6 C4 P0lyrner 2. 1 3.0 Isobutane 0. 9 1. 3 Normal Butane 4. 6 6. 5

Total 7l. 0 100. O

Anti-knock qualities of gasoline:

CFR Research Octane Number (with 2.6 cc.

tetraethyl lead) 105.5 ASTM Motor Octane Number (with 2.6 cc.

tetraethyl lead) 98.9

Table I shows that the novel process can be adjusted so that the entire feed is converted into gasoline constituents which, upon being combined, produce a gasoline blend which has excellent anti-knock properties and possesses enough volatility to satisfy winter requirements. 71 volumes of gasoline product are obtained in this manner per 100 volumes of C -C. feed, the difference in volume being due to the fact that the product is considerably denser than the light hydrocarbon feed.

CFR Research 0. N. (with 2.6 cc. tetraethyl lead)- 103.1 ASTM Motor 0. N. (with 2.6 cc. tetraethyl lead) 88.9

Table II shows a product obtained from essentially the same feed in an alternative operation. Here the combination process was operated so as to convert the feed into a gasoline blend of excellent anti-knock characteristics and sufiiciently low vapor pressure suitable for summer use.

By comparison with Table I it will be observed that, to meet summer specifications, it is desirable to hydrate only a minor proportion of the propylene while alkylating most of it. Some butylenes are also alkylated to reduce volatility further. The remaining C and C olefins which cannot be alkylated because of insufficient isoparaflin are then converted into gasoline by polymerization. Conversely, to meet winter specifications, most or all of the propylene can be diverted to the hydration step while being replaced in the alkylation step with butylenes so as to make full use of the isoparafiin available. In either case the polymerization step serves as a kind of fiy wheel which keeps gasoline production at a maximum by utilizing the olefins left unconverted in the hydration and alkylation steps.

Tables I and II illustrate the unusual flexibility of thenovel process in that they demonstrate that this process is entirely self-sufiicient to produce gasoline blends meet- Thus, gasolines can be produced which have Reid vapor pressures of about 7.5 to 13.0 p. s. i. g. and distillation characteristics such that l8'to about 60 percent will be volatile at 158 F. Such gasolines may contain, for instance, about 5 to 36 volume percent of the hydration product, about 2 to 40 volume percent of gasoline-range polymer of a C C olefin, about 35 to 60 volume percent of an alkylate having 7 to 8 carbon atoms per molecule, and about 5 to 10 parts of butanes. Of course, the process can also be operated in conjunction with conventional refining operations. In such a case the final gasoline blend may contain various amounts of extraneous constituents such as virgin, catalytic and reformed naptha, the process of the invention being operated under conditions adjusted to satisfy the volatility specifications of the final blend while maximizing the particularly desirable constituents such as hydration product and alkylate.

In summary, the foregoing shows that the main value of the integrated process lies in its ability to provide maximum yields of products which are very high in certain critical motor gasoline inspections, notably octane number and volatility. Furthermore, the integrated process is unusualy flexible and thereby adapted to meet fluctuations due to seasonal product quality requirements or available feed supply. According to this invention superior products are obtained from the light ends which are available in any normal fuel products refinery, particularly in one which includes catalytic cracking facilities.

Secondly, the integrated process is valuable in that it provides compensations for certain limitations which characterize the several component steps individually. For instance, the relatively high volatility of the hydration product tends to offset the relative lack of volatility of the alkylate, thereby making more paraflins available for valuable alkylate production. The relatively poor octane blending factor which normally characterizes polymer gasoline is kept to a minimum since in the present invention polymerization can be largely or even totally replaced by hydration which produces a fuel component of greatly superior blending value. Polymerization is used here only as a means of controlling the isoparaffin/ olefin ratio for alkylation. Where surplus olefins can be used elsewhere, the present process need not contain any polymerization step at all.

Finally, the drawback of low conversion which normally characterizes olefin hydration is overcome in the integrated process in that the desired conversion is completed in the efficient alkylation stage, rather than attempting to complete conversion by recycling to the hydration stage. mizes conversion in a particularly advantageous manner. In addition, the process has an advantage in that the olefin feed which is sent to alkylation from the hydration step contains a greater concentration of olefins than a catalytically cracked C cut ordinarily used for alkylation.

The characteristics of the individual stages of the process are summarized in Table III.

Consequently, the present process maxi-.

gamed T ableIlI LIGHT ENDS C QNV ERSIO N' Process Catalytic-Polymerl- 'DirectHydration' Alkylatlon V ,.zation 5 7 Olefin Feedstock Cr Ca Ca? .,C4".. 7 Maximum conversion-percent on olefin feed. 95 -50 100 ,100. Other Feedstocks 7 N n .-Nm1 10 104; Products .Motor Gaso. Poly.; .Propylene bydra- Light alkylate; Heavy alkylate;

C4 stream of variable olefin content 63-55%).

tion product plus able olefin con- Alkylate Btms; i0 concentrate;

stream of varin0 concentrate.

tent (IS-90%).

, Ct- Polymer CtHydr. Product 7 Ca' Alky. Cr Alky.

Motor Gasoline Quality: 7 a i r Efleetive Blending RVP, p. s. i. g 1.5 19.2 2.5. Proportion Distilled at 158 F. (D+L) -6 134 .0 .0.

Percent. Research,Blending No. a

(clear); 72;101'.2.0N--.- '70; 99.5 ON 63:92.2 ON 65.1; 94.5 ON. (+2.6 cc. TEL) 76; 103.8 0N 79;.1051 ON 73; 102.3 ON 74.3; 102.9 ON. Blending ASTM Motor ON V (clear 83- .6.

(+2.6 cc. TEL) 86 94. Vapor Lock Constant 2 0 1 Reid vapor pressure. Vaporlock constant C'.=.(5 RVP+percent distilled at 158 F.).

It can be seen that catalytic polymerization reacts olefinsonly, over a wide range of conversions, to a relatively nonvolatile gasoline stock of good research but only fair motor octane number. Substantially complete conversion of the olefins canbe achieved. This affords a convenientmeans of completely utilizing the olefins as far as they cannot be used up in the other steps of the. process. Also it is an effective way of preparingan isoparaflin concentrate suitable for alkylation.. If desired, the:resulting isobutane or. iscpentane content offlth'e concentrate may be further increased by isomerization;

The direct hydration of propylene and/0r butylenes high totalconversion.

Table IV 'CONTROL OF GASOLINE QUALITY Origin of Gasoline CaseNo. 1-Process of Invention Only Case No. 2-Process of Invention plus Conventional Practice Desired Increase In-.- Research Octane No Prlmarylcontrol Diverting olefin feed-from alkylation to hydration.

Secondary Control Conventional Control.

Tetraethyl lead concentration. Usually also reformation to polymerization.

. ing or hydroforming. Motor Octane No Divert Olefin feed from Divert olefin from polymeri- Do.

' ,alkylation to hydration. zation to alkylation. Volatility .Dlvert propylene from alky- Divert butylenes from poly- Divert C4 hydrocarbons from V I lation-tohydration. Also menzatiori to, alkylation. conversion steps to gasoline divert Cr hydrocarbons Also propane can be blending. Also thermal from alkylationtogesoline blended into gasoline if reforming or heavy virgin blending. no 0 hydrocarbons are naphtha.

* j available.

.lCf/olefin balance to alkylation plant- Divert propylene from alkyl-. Divert butylenes from alkylation' to hydration.

reactsithe olefin only, and to a limited degree. The resulting productthas good research octane and superb motor octane quality. However, due to azeotropic effects, it is highly volatile. inadmixture with hydrocarbon gasoline components, andthis effect must becounter j Having described thefjgeiierfa natufnandflspecific-zexamples illustrating the invention,---itwill-be"un'derstood that the latter. can be mbdifidIinivafioiisfwayswithout: departingfrom'the scope and spirit hereof. The novelty of'the present invention is particularly pointed out in the appended. claims. 7

'What'is claimed is: v V a 1. 'A process 'for converting a hydrocarbon feed supply ofrc andtC paraffins, andolefins into gasoline components of variahlefpredetermirie'd' volatility and good anti-knock characteristics, which. comprises segregating from, said. feed hydrocarbonsan olefin-rich C fraction containin'gl70 to 95 propylene and a"C fraction containing butylenes and isobutane, feeding at least a portionof said olefi n rich ,C fraction and water of hydration dnto'a hydration 'zone' containing" a hydra tion i catalyst under conditions :conducive- .to producing an grated process, four major variables must be considered: oxygenated liquid boiling principally between about 50 and 95 C., recovering said oxygenated liquid and an unconverted propylene-containing fraction, recycling a portion of said unconverted fraction to said hydration zone, thereby adjusting the ratio of unconverted propylene to propylene converted to oxygenated liquid, passing a sufficient portion of said C fraction through a polymerization zone containing a polymerization catalyst under conditions conducive to the formation of gasolinerange polymer to thereby adjust the butylene content of the remaining unpolymerized C fraction such that the isobutane present therein is just about sufiicient to alkylate all the remaining unconverted olefin, recovering said gasoline-range polymer, feeding said unpolymerized C fraction and all the unhydrated C fraction to an alkylation zone containing an alkylation catalyst under conditions conducive to converting said fractions into an alkylate of which at least 90% boils between about 50 and 220 C., recovering said alkylate, and controlling the quality of the resulting gasoline components by increaseing the ratio of hydration zone olefin feed to alkylation zone olefin feed plus polymerization zone olefin feed when increased product volatility is desired, and by decreasing said ratio when decreased product volatility is desired.

2. A process according to claim 1 wherein butylene polymerizaton is increased in relation to butylene alkylation as propylene alkylation is correspondingly increased in relation to propylene hydration, in order to reduce product volatility, and wherein butylene alkylation is increased in relation to butylene polymerization as propyl- 14 ene hydration is correspondingly increased in relation to propylene alkylation, in order to increase product volatility.

3. A process according to claim 1 wherein substantially the entire C fraction is passed through the hydration zone and as much of the unconverted propylene from the hydration zone is mixed with the C fraction as will produce a mixture having a proper isobutane propylene ratio for feeding to the alkylation zone while remaining butylenes are fed to the polymerization zone.

4. A process according to claim 1 for producing a relatively volatile combination of gasoline components, which comprises converting substantially all available propylene in the hydration stage.

5. A process according to claim 1 wherein the hydration catalyst is selected from the group consisting of phosphoric acid catalyst, active silica gel catalysts and reduced tungsten pentoxide catalysts.

6. A process according to claim 1 wherein said a1kylation catalyst is selected from the group consisting of 88-98% sulfuric acid, hydrogen fluoride, boron fluoride, and aluminum chloride.

References Cited in the file of this patent UNITED STATES PATENTS Re. 20,738 Metzger May 24, 1938 2,256,880 Goldsby et al Sept. 23, 1941 2,408,999 Robertson Oct. 8, 1946 2,409,544 Clarke Oct. 15, 1946 2,576,071 Howes et al Nov. 20, 1951

Claims (1)

1. A PROCESS FOR CONVERTING A HYDROCARBON FEED SUP-PLY OF C3 AND C4 PARAFFINS AND OLEFINS INTO GASOLINE COMPONENTS OF VARIABLE PREDETERMINED VOLATILITY AND GOOD ANTI-KNOCK CHARACTERISTICS, WHICH COMPRISES SEGREGATING FROM SAID FEED HYDROCARBONS IN OLEFIN-RICH C3 FRACTION CONTAINING 70 TO 95% PROPYLENE AND A C4 FRACTION CONTAINING BUTYLENES AND ISOBUTANE, FEEDING AT LEAST A PORTION OF SAID OLEFIN-RICH C3 FRACTION AND WATER OF HYDRATION INTO A HYDRATION ZONE CONTAINING A HYDRATION CATALYST UNDER CONDITIONS CONDUCTIVE TO PRODUCE AN OXYGENATED LIQUID BOILING PRINCIPALLY BETWEEN ABOUT 50* AND 95*C., RECOVERING SAID OXYGENATED LIQUID AND AN UNCONVERTED PROPYLENE-CONTAINING FRACTION, RECYCLING A PORTION OF SAID UNCONVERTED FRACTION TO SAID HYDRATION ZONE, THEREBY ADJUSTING THE RATIO OF UNCONVERTED PROPYLENE TO PROPYLENE CONVERTED TO OXYGENATED LIQUID, PASSING A SUFFICIENT PORTION OF SAID C4 FRACTION THROUGH A POLYMERIZATION ZONE CONTAINING A POLYMERIZATION CATALYST

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