US2396198A

US2396198A - Alkylation of hydrocarbons

Info

Publication number: US2396198A
Application number: US594216A
Authority: US
Inventors: Ernest F Pevere; Louis A Clarke; George B Hatch
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1945-05-17
Filing date: 1945-05-17
Publication date: 1946-03-05
Anticipated expiration: 1963-03-05

Description

2 Sheets-Sheet l March 5, 1946. E. F. PEVERE ETAL ALKYLATION OF HYDROCARBONS original Filed July 29, 195sl March 5, 194v E. F. P EvERE ETAL ALKYLATION OF HYDROCARBONS Original Filed July 29, 1938V 2 Sheets-Sheet 2 hold=up in the mixer.

contacted with the used acid and the mixture then transferred through the line l to av set tier id wherein the hydrocarbons collect as a layeriri the upper portion and the acid in the -lower portion thereof. i constant level of acid may he maintained in the lower portion oi the settler and the excess acid withdrawn through the valve controlled line le in which is located apump te actuated by an automatic level control device il. any portion of the acid may be recycled from the settler it to the mixer l through the line i9 and pump 2li to maintain the desired acid The pump 2@ may be ccntroiled by a flow meter to recycle the desired amount of acid or a proportioning pump may be used instead of pumps iii and 2d.

Additional olefinic charging stock. may be introduced through the line 2E into the hydrocarloon layer in the upper portion of settler i9. The feature of prediluting the olen feed to an a1- lrylatlon reaction zone with separated hydrocarbon phase or alkylate containing a high proportion of isoparaflns prior to contacting the olefin with the alkylation catalyst is disclosed and claimed in copending application, Serial No.

392,396, filed May 7, 1941, as a continuation-inpart of copending application, ySerial No. 214,488, illed June 18, 1938. The resulting mixture is then transferred through the line 2d to a second mixer 25 wherein the hydrocarbons are intimately contacted with used acid introduced into the lower portion thereof, through the line 2S. The mixture of hydrocarbon and acid is passed through the line 2l to the second settler 29 wherein the acid and hydrocarbon stratify. The used acid is withdrawn from the lower portion of the settler through theline 8, referred to heretofore, in which is located a pump 29 actuated by a constant level mechanism 30. Any portion of the -used acid may be withdrawn from the lower portion. of the settler through the line 32 and pump 93 and introduced into mixer 25 to create the desired acid hold-up therein. Oleflnic charging stock may be introduced into the upper portion of the settler through the line 35 and the resulting hydrocarbon mixture transferred from the settler 28 through the line 36 to a third mixer 38. The hydrocarbons in the mixer 38 are intimately contacted with the used acid introduced into the lower portion thereof through the line 39. The acid and hydrocarbon mixture is transferred from the mixer 38 by the line d!) to a third settler d2. lAcid and hydrocarbons separate in the settler, the acid being withdrawn from the lower portion thereof through the line 2B, in which is located pump i4 actuated by a constant level mechanism 45. Acid is withdrawn from the bottom of the settler 42 through the line 4l and pump 48 to the mixer 3B to provide the desired acid hold-up in that mixer. Olenic charging stock may be introduced into the upper portion of the settler l2 through the line 5U.

The branch lines lll, 22, 35 and 5l! communi^ cate with an oleflnic hydrocarbon charging line 52 in which is located a pump 53. By suitable regulation of the valves shown in the lines l0, 22, 35 and 59, the olennic hydrocarbon'charge may be split between any or all of the settlers it, 28 and t2. The feature 0f splitting the olen feed to an alkylation system, whereby the olen is simultaneously introduced at a number of spaced points, is disclosed and claimed in copending application, Serial No. 213,148, led June 1l, 1938, now Patent No. 2,260,990. Also a portion or all oi' the olenic charge may be introduced into the mixer i through the line i9, 'out ordinarily it is preferable to make a multiple injection of the olenic charge between only the settlers itl, 2li, and d2. This oleflnic charge may be any olens which will allrylate the isoparanins, such as normally gaseous oleiins of more than two carbon atoms, or polymers thereof, including Cs or C4 fractions of cracked gases or mixtures thereof; propylene; butylene; isobutylene; polymer gasoline; diisobutylene; or a butene-isobutene mixed polymer.

The hydrocarbon mixture in the top of settler l2 is passed through the line 55 to a fourth mixer 5d wherein it is contacted with acid introduced into the lower portion thereof through the line iii?. The acid hydrocarbon mixture is vconducted from the mixer 59 through the line 59 to a fourth settler Sii. The acid separating in the settler iid is passed through the line t9,l referred to heretofore, to the mixer 38. Also acid is pumped from the lower portion of vsettler t@ through the line G2 to the mixer 5d to maintain the desired acid hold-up in the latter mixer. Hydrocarbons are passed from the upper portion of settler 59 through the line Gi to mixer d5 wherein the hydrocarbons are intimately contacted with fresh acid introduced into the lower portion thereof through the line El by the pump t8. This acid may be sulfuric acid around 92 to 98% strength and preferably about 94 to 96% concentration. The mixture of hydrocarbon and acid is conducted from the mixer 65 through the line 69 to a settier lll in which the acid collecting in the lower portion thereof is withdrawn through the line' 59 referred to heretofore. Any portion of this spent acid may be pumped through the line 'l2 to the mixer 65 to produce an acid hold-up therein.

The hydrocarbons are passed from the upper portion of settler l@ through the line 'itl to a neutralizer or mixer l5 wherein the hydrocarbons are intimately contacted with an alkaline reagent. such as dilute caustic soda or soda ash solution, introduced through the line ll and pump 18. The mixture of hydrocarbon and neutralizing agent is passed through the line E@ to a settler 3l where# in the neutralizing agent separates out as a layer in the lower portion thereof and may be recycled through the line 82 to the mixer l5 or withdrawn from the system through the valve controlled line 33.

rlhe neutralized hydrocarbons are passed from the upper portion of settler Si through theline 8d to fractionator 85. In the latter fractionator the hydrocarbons are distilled to produce bottoms of higher boiling point than gasoline, which may be withdrawn from the lower portion of the fractionator by the line 8B, while the gasoline hydrocarbons and lighter pass overhead from the fractionator through the line 89 to a secondary fractonator or stabilizer 90 wherein a liquid fraction, comprising gasoline, is fractionated out and withdrawn from the lower portion 0f the fractionator through the line 9i. The normally gaseous hydrocarbons, including isobutane and lighter, and a. portion or all of the butane, are fractionatecl to separate the gases lighter than isobutane which may be removed from the upper portion of the fractionator through the valve controlled line 93. A side stream rich in isobutane may be withdrawn through the valve controlled condenser til and collected in the accumulator A portion or all of the product-in accumuiator et may be recycled through the line t, referred to heretofore, in which is located pump itil.

ln passing through the reaction zone, the isoparamns are alici/lated by the olens in the presence of a sulfuric acid catalyst to produce branch chain parafilns comprising a mixture of about the boiling range of gasoline. The temperatures maintained in the reaction zone may be about il to d" F. and preferably about60 to 90 F. Sumcient pressure is maintained to keep the hydro carbons substantially in the liquid phase. Best results are obtained when using an excess of isoparaiiins and the molar ratio of isoparamns to oleiins may range between about 1:1 and 5: 1, and preferably about 3:1. The overall of acid dosage should be between about one-half to three parts by weight of acid to one part of olen. The acidolefin ratio maybe controlled by regulating the proportions of acid to total hydrocarbons in the iresh feed. The Weight ratio of acid to total hydrocarbon or acid dosage in the individual reactors may range between about 2:1 and 5:1 and preferably above 3: l. The ratio may differ among the various reactors. The latter ratio may be regulated by the amount of acid hold-up created by recycling acid to the mixer.

In Figure 2 is showna modified type of apparatus for carrying out a concurrent iiow operation. The isoparafiin-'hydrocarbon charge, introduced through the line 02 by the pump itt. and the fresh acid charge, introduced through the line itt by the pump itl, are charged to the nrst ci a series of mixers its, |09, ilil, lll and iii, wherein the hydrocarbons are intimately contacted with the acid. The olefin charging stock, introduced through the line H5, in which is located pump i i t, may be split into one or more of the reactors by means of the branch lines lid, llt, it@ and B2i. After each mixer a settler is located, designated by the numerals l|25, |26, i2l, 'lit and itt. The acid and hydrocarbon mixture, iiowing from one mixer into the next succeeding mixer, passes through a settler wherein acid is allowed to settle out. The acid settling-out in these settlers may be withdrawn in any desired amount through the lines iti, i3?, 33, i3d and ist and introduced into the lower portion of the rio-operating mixer, to produce the desired amount of acid hold-up therein. It is to be understood that only a portion of the acid may be separated inthe settlers either by incomplete set tlingor by passing only a portioirof the hydrocarbon-acid mixture through the settler, the remainoler going through a by-pass line, not shown.

through the line itt. All or any portion oi this J acid may be recycled to the mixer itt through the line lill, by the pump itt.

The hydrocarbons pass from the upper portion of the settler itt through the line itt to a neutralizer, not shown, to he subsequently processed, substantially as shown in Figure 1. Recycle hydrocarbons, comprising isobutane, may be recy cled from the fractionating system, not shown, through the line iet by the pump itt, which correspond to line e and pump ttt of Figure 1.

According to one method of operation, the acid hold-up in the various mixing sections may be maintained entirely or in part by recycling the acid from the bottom o.' the nal separator itt and introducing this recycled acid into each of the mining zones through the manifold lines Mt, tilt, itt, it?! and Mit by suitable regulation ci the valves therein. In such an operation, the settlers itt, itt, itl, it@ and it@ may be dispensed with or bi1-passedl through lines not shown, and the hydrocarbon-acid mixture conducted directly to the succeeding miner without any inrvening separation or recycling of the acid. i

Referring to Figure 3, there is shown a mixer tilt associated with a cooperating settler H56. The mixer and settler may comprise a stage of an alirylation unit employing either countercurrent or concurrent flow. The hydrocarbon is introduced into the mixer through line itt and the acid through line its. The reaction mixture is transferred through the line E50 to the settler |58 which is provided with a sight glass it! for observing the acid level therein. The hydrocarbon settling out in the upper portion of settler |58 is withdrawn through the line itil. A plurality of draw-off lines itt, itt and itt connect with the settler at various elevations to control the acid level by regulation of the valves therein. The acid is allowed to iiow from the settler to the mixer through the line i't to create the desired acid hold-up which is regulated by the height of the acid level in the settler. The gas pressure in the system is edualized by means oi the gas line it which communicates with the mixer and settler through the lines its and ilu respectively.

In a unit comprising a plurality of stages the acid levels may be maintained at progressively increased didierential pressure between stages or any variable diierential pressure may be maintained between the stages whereby any desired hold-up may be created in thevarious mixers, for acid hold-uppurposes therein. This method is particularly suitable for a countercurrent operation. y

It is contemplated that the desired amount of acid hold-up may be controlled in the individual mixers by regulating the acid levels or pressure head of acid in each of the cooperating settlers, or that the acid hold-up in the mixers may be controlled as a group by regulating the acid level or pressure head of acid in the iinal settler only.

is an example of the operation of the invention, isobutane and Ca and C4 hydrocarbons from cracking stili gases, the ratio of isobutane to oleilns inthe over-all charge being about 3:1, were treated in a hva-stage concurrent system, using multiple injection of the olens in the second, third and fourth stages. Sulfuric acid of about 96% strength was used as the catalyst, the ratio 4 by weight of acid to oleiins in the fresh feed be- `suiiicient returned to the mixing zones to maintain aratio'of'acid to total hydrocarbon in the f approximately 1.8 to l by weight. The hydrocarbons were maintained substantially in the liquid phase and the temperatures maintained at about 65 lf". Used acid and excess isobutane were recycled. A yield of aviation grade gasoline, having an octane value oi about 90, amounting to about l40% based on theolefins, was obtained.

Obviously many modifications and variations of the invention, as hereinbeiore set forth, may be made `without departing from the spirit and scope thereof, and only auch limi-tations should be imi low-boiling isoparafiin with an olefin for the production of normally liquid hydrocarbons within the gasoline boiling range, which comprises conf.

tinuously introducing in liquid phase and passing serially through a plurality of agitated reaction zones ofan alkylation system maintained under alkyiating conditions, a low-boiling isoparaiiin and strong sulfuric acid of alkylati'on strength, contacting an olefin in liquid phase with the isoparaffin and acid in said zones to effect alkylation of the isoparaiiln with the olefin, continuously withdrawing hydrocarbon reaction products and acid from said system, continuously discharging a minor proportion of the said acid, and continuously recycling the remaining major proportion of acid in controlled amounts to each oi' a plurality of said zones to provide a high acid holdup in the system and independently maintain in each of said zones a weight ratio of acid to total hydrocarbons of about 2:1 to 5:1, the weight ratio of acid to total hydrocarbons maintained in each of said zones being substantially greater than the weight ratio of acid to total hydrocarbons in the fresh feeds to said system.

2. A continuous process for the alkylation of a low-boiling isoparaiiin with an olefin for the production of normally liquid hydrocarbons within the gasoline boiling range, which comprises continuously introducing in liquid phase and passing serially through a plurality 0i' agitated reaction zones of an alkylation system maintained under alkylating conditions, a low-boiling isoparaffln and strong 'sulfuric acid of alkyl-ation strength,

, contacting an olen in liquid phase with the isoparaffin and acid in said zones to effect alkylation of Vthe isoparaiiin with the olefin, continuously withdrawing hydrocarbon reaction products and acid from an intermediate zone of said system, separating the withdrawn hydrocarbon reaction products from the acid and passing the hydrocarbon reaction products to a succeeding zone of the system, recycling a portion of the separated acid to the said zone from which it was withg drawn. passing another portion of the separated -other portion of the acid phase together with fresh feed acidare supplied to said reaction zone to make up for that withdrawn with said reaction products, the improvement which comprises maintaining in said alkylation Areaction zone. a weight ratio of acid to total hydrocarbons within the range of about 3:1 to 5:1, and maintaining a substantial acid holdup relative to hydrocarbons in the said alkylation system, such that the rate of iiow of hydrocarbons through the system and discharging therefrom is at least twice the rate of iiow of acid through the system and dischargi'ng therefrom, whereby the advantages of a low overall acid dosage with a high acid-to-hydrocarbon ratio in the reaction zone are obtained.

4. In a continuous process for the alkylation of a low-boiling isoparaifin with an olefin in an alkylation-system having a plurality of alkylationv stages for the production of normally liquid hydrocarbons within the gasoline boiling range, wherein the low-boiling isoparaiiln and strong sulphuric acid of alkylation strength iiow serially through the plurality of alkylation stages and are reacted with olefin therein under alkylating conditions, the improvement which comprises maintaining a substantial acid hold-up relative to hydrocarbons in each of a plurality of said stages. and .independently controlling and varying the extent of acid hold-up maintained in at least one of said stages from the extent of acid hold-up maintained in another of said stages.

5. In a continuous process for the alkyiatlon of a low-boiling isoparamn with an olen in an alkylation system having a plurality of alkyiation stages for the production of normally liquid hydrocarbons within the gasoline rboiling range,

acid to another alkylation zone of the system,

continuously withdrawing hydrocarbon reaction products and acid from an end Zone of the system and separating the same, continuously discharging a minor portion of the separated acid from the system. and continuously recycling the re maining major portion of the separated acid to the said zone, the said acid recycles providing a high acid hold-up in the system and continuously maintaining in each of said reaction zones a weight ratio of acid to total hydrocarbons of about 2:1 to 5:1, and which is substantially great. er than the weight ratio oi acid to total hydrocarbons in the fresh feeds tosaid system.

3. ln a continuous process for the alkylation of a low-boiling isoparaffin with an olefin in an alkylation system for the production of normally liquid hydrocarbons within the gasoline boiling range, wherein the low-boiling isoparaiiin and olefin with the isoparaiin in substantial molar excess of the olefin are simultaneously ied to an alkylation reaction zone oi said system contain-s ing strong sulfuric acid of alkylation strength, the

hydrocarbons in liquid phase and the acid are wherein the low-boiling isoparaiin and strong sulfuric acid of' aikylation strength flow serially through the plurality of alkylation stages andthe isoparafiin is reacted with olefin therein under alkylating conditions, and the resulting reaction products fiow to a ilnal settling zone where hydrocarbons are separated from the acid, the improvement which comprises returning acid from the said nal settling zone in independently controlled amounts to a plurality of said alkylation stages, whereby the extent of acid hold-up in each of said alkylation stages is independently and variably controlled.

6. In a continuous process for the alkylation of a low-boiling isoparaiin with an oleiin in an alkylation system for the production of normally liquid hydrocarbons within the gasoline boiling range, wherein the low-boiling isoparaiin and olefin are introducedsimultaneously into an aikylation reaction zone and reacted in the presence '0f strong sulfuric acid oi aikylation strength under alkylating conditions, and the reaction products flow to a settling zonelwhere acid is settled from rthe hydrocarbons', the improvement which comlmlatlon system having a plurality oi ailmlation stages for the production oi normally liduid hydrocarbons within the gasoline boiling range. wherein the low-boiling isoparamn and strong sulfuric acid of alhylation strength dow serially through the plurality of allrylation stages and the isoramn is reacted with tlievolen therein under alltylating conditions, each stage oi? said system comprising a reaction zone and a cooperating settling none, the improvement which comprises eduallzing the pressure between a reaction zone and its cooperating settling zone of each stage. returning acid from the settling zone to the cooperating reaction zone of each stage in accordance with acid level in the settling zone thereof,-

controlling acid hold-up in each stage by regulating the height of the acid level in the cooperating settling zone'thereof, and mainta a dierent acid level in a settling zone of one stage from that maintained in another stage to thereby provide diderent acid hold-ups in said stages.

8. In a continuous process for the alkylatlon of a low-boiling isoparamn with an oleiin in the presence of strong sulfuric acid for the production of normally liquid hydrocarbons within the gasoline boiling range, wherein the isoparanin and olefin are continuously introduced into an agitated reaction zone of an allryiation system and reacted in the presence of strong sulfuric acid under concile tions to cause allxylation of isoparailin with the oleiin to produce normally liquid hydrocarbons lwithin the gasoline boiling range, and a stream ol reaction products is continuously discharged from said agitated reaction zone, the improvement which comprises passing the discharged stream to an initial settling acne, partially settling acid from the reaction products in said initial settling Zone, recycling settled acid to said reaction zone, and continuously passing a stream of hydrocar- ,bon reaction products with retained acid resulting from said partial settling operation to a l ysettling zone where the hydrocarbon reaction products are separated from the retained acid.

9. 'lhe process according to claim d, wherein at least a portiouoi the acid separated in said nal y settling zone is discharged trom the alkylation system, and fresh acid is added to the aikyiation system to maire up for that discharged therefrom.

lo. lne continuous process for the alhylation of a low-boiling lsopara with an olenn in'an aiirylation system having a plurality of alkylation stages lor the production oi normally liquid hy drocarbons within the gasoline boiling range,

wherein the impares and Silrig Slilllllcndcld of alleylation strength dow serially through a pluf rality of alhyiation stages and the isoparamn is reacted with olehn therein under allsylating conditions, the improvement which comprises incom pletely settling acid irom the hydrocarbon reaction products oi one stage, passing the resultant incompletely settled hydrocarbon reaction products with retained acid to another allrylation stage ci the system, and recycling separated acid to the said one stage from which it was withdrawn, whereby the acid hold-up in said one stage is dependent at least in part upon the extent oi settling of acid from reaction products of that stade..

' il. Process for the allrylation oi hydrocarbons which comprises continuously charging an olefin, an excess oi low-boiling isoparamn and a liquid acid allrylation catalyst into a mixing zone Where the hydrocarbon and acid phases are thoroughly mined under allrylating conditions, introducing the resulting mixture into the upper portion of a primary settling zone in which at least a partial separation of acid and hydrocarbon phases is eected, withdrawing settled acid from the lower portion of said 'primary settling none and recycling it to said mixing zone, withdrawing a mixture of hydrocarbon and acid resulting :rom said partial settling operation from said primary set tling zone, and passing said withdrawn mixture to a. second settling zone where hydrocarbons sepa rate from acid.

l2. The process 'which comprises charging an isoparailin and an oleiln to an agitated reaction zone containing a liquid allsylation catalyst oi greater density than thevhydrocarbons undergoing treatment, mixing the hydrocarbons and catalyst therein under alkylating conditions to allryiate isoparain with the olefin. passing a stream of the resulting reaction products to `a primary settling zone where incompietesettllng of hydrocarbons and catalyst occurs, recycling a liquid stream irom the lower portion or' said primary setthng zone to the reaction acne', anopassing another liquid stream lrom a higher eleva.- tion of said primary settling zone to a second settling zone where separation or' remaining cat:- lyst irom hydrocarbons occurs..

13. 1n the alsyiation or an isoparamn with an olerln in the presence or' a liquid alici/lation catalyst of greater density than the liyoi'ocaroons undergoing treatment, the method which comprises maintaining zones oi agitated reaction,

partial settling and unal settling in series, mixl to the i'lnai settling zone where remaining catalyst settles out of the hydrocarbons.

i4. Ina continuous process for the allrylation of a low-boiling isoparahin with an olenn in an aikylation system having a plurality or alirylation stages ior the productionl or' normally liquid hydrocarbons within the gasoline boiling range. wherein the low-boiling isoparamn and a liquid. allai/lation catalyst now serially through the piurality of allsylatlon stages and are reacted with olerin therein under ailrylating conditions, the improvement which comprises maintaining a substantiai catalyst hold-up relative to hydrocarbons in each of a plurality of said stages, and inclepenoently controlling and varying the extent of catalyst hold-up maintained in at least one of said stages irom the extent of catalyst hold-up maintained in another of said stages.

15. 1n a continuous process ior the alhylatioxi of a low-boiling isoparaiin with an olenn in an allrylation system having a plurality of alaylationA separated from the catalyst, the improvement I which comprises returning catalyst from the said final settling zone in independently controlled amounts to a plurality of said allsylation stages,

' ing conditions, and the reaction products iiow to a settling zone where catalyst is settled from the hydrocarbons, the improvement which comprises equalizing the pressure between the said reaction and settling zones, returning catalyst from the settling zone to the said reaction zone in accordance with the catalyst level maintained in said settling zone, and controlling catalyst hold-up in said system by variably regulating the height of the catalyst' level in said settling zone.

17. In a continuous process for the alkylation of a. low-boiling isoparafn with an olefin in an alkylation system having a plurality of alkylation stages for the production of normally liquid hydrocarbons within the gasoline boiling range, wherein the isoparamn and a liquid alkylation catalyst flow serially through a plurality of alkylation Stages and the isoparafiin -is reacted with olefin therein under alkylating conditions, the improvement which comprises incompletely settling catalyst from the hydrocarbon reaction products of one stage, passing the resultant in; completely settled hydrocarbon reaction products with retained catalyst to another alkylation stagey of the system, and recycling separated catalyst to the said one stage from which it was withdrawn, whereby the catalyst hold-up in said one stage is dependent at least in part upon the extent of settling of catalyst from reaction products of that stage.

ERNEST F. PEVERE. LOUIS A. CLARKE. yGEORGE B. HATCH.