CA2027574A1 - Integrated separation method for di-isopropyl ether and methyl tertiary alkyl ether processes - Google Patents

Abstract

The process for manufacturing tertiary alkyl ethers such as MTBE, TAME and isopropyl tertiary alkyl ether and that for manufacturing di-isopropyl ether (DIPE) are integrated into an overall process to produce high octane gasoline rich in these ethers. The integration is preferably achieved in a combined separation step where the effluents from both etherification processes are fed to a water wash tower for separation into an organic phase containing C3+ hydrocarbons and oxygenates including C4+ ethers and an aqueous phase which contains methanol and isopropanol. The aqueous phase is recycled to the DIPE etherification zone while the organic phase is debutanized to produce a bottom stream comprising high octane gasoline rich ethers and an overhead stream comprising C4- hydrocarbons. The water wash step allows large excess quantities of methanol to be used in the MTBE etherification step without recycle. The invention advantageously employs a common water washing step and common debutanizing step in the manufacture of tertiary alkyl ethers and DIPE.

Description

~; WO 90/11267 PCI~/US90/01479 Ihis inve~tio~ lates to an ir~atetl pr~c~s and means for the pro~ctio~l of high octane gasoline ric~ in met~yl tertiary al~yl ether and di-is~r~yl et~er. ~x partiallarly, the i~entian relates to a na~ ethod for Irbinir~ the separation of the independent product streams from the manufacbure of di-iscpropyl ether and methyl t ~ alkyl ether in the course of the prcduction of high octane gasoline c~rt~}ning such ethers.

3riven by the need to elimunate lead based octane e=hancrrs in gasoline, prccesses to produoe high octane gasolines blended with lower aliphatic alkyl ethers as octane boosters and supplementary fuels have been vigorously develcped in the petrDleu~ refining arts. C5-C7 methyl alkyl ethers, especially methyl tertiary butyl ether ~MrEE) and t ~ a~yl ~ethyl ether (TWME) have been found particularly useful for enhancing gasDlmne octane. Therefore, i~prcvements to the pnlcesses related to the pc~ou=t~on of ~h~ce ethers are matters of high i~portance and s~bstantial challenge to research wDrkers in the petrDleum refining arts.
It is well known that iscbutylene may be reacted with methanDl over an acidic catalyst tD provide methyl tertiary butyl ether (MIEE) and isoamylenes may be reacted with nethanol over an aci~r catalyst to produce tertiary amyl methyl ether (TWME).
The reaction is a useful pclparatian for these valuable gasoline octane enhznrY~s and is typical of the reaction of the addition of primary to the ~re reactive i 3'~

tertiary alXenes typ ~ 2 or R2C-CHR un~er mild conditions to form the oorrespond mg te~t~lry aIkyl ethers of lower alkanol, particularly methanol, ethanol and isopropur~l.
The feedstock for the etherification reaction may be taken from a variety of refinery prooess streams such as the unsaturated gas plant of a fluidized bed catalytic cracking operation containing mixed light olefins, preferably rich in i ~ ylene. Light olefins su~h as prqpylene and iscmers of butene other than isobutylene in the feedstock are essentially unreactive toward primary alcohols under the rild, acid catalyzed etherification reaction canditions emplcyed to praduce lower alkyl tertiary butyl ether.
In these etherifi ation processes, a major prcblem importanoe is the separation of methanol L~u~ the etherification reaction product due to the proclivity of methanol to form a very dilute aze~tL~pic mixture with hylr~caroons and the strong solubility of ne*hanol in bakh water and hythYx3arbons. ~hile it wculd ble useful fram an e~uilibrium standpoint to use large excesses of meth~nol in etherification, ~ubs~guent separation problems have limited that prooess lmprcvement. Due largely to these factors, the co6t associated with DY*~Y~nOl ~qpRration and recycling in the e~herification reaction repclserts a4prcximote1y 30~ of the ccst of the total e~herification prccess.
Lower mol~~1lar weight alcohols and ethers such as isoprqpyl alcohol (IPA) and ~ii~qpropyl ether (Dl~) are in the gasoline boiling range and are known to have a high ble ~
oc$ane ~niber. They, as well as ~n~3E and T~ME, are useful octane erbor=ers. In addition, by-prcduct E~x~ylene from which IPA and DIPE can be ~ade is usually a ~ le m a ~els ref ~ . The pE*IoChericals i ~ also pro*uces mu~dhIres of light olefin streams in the C2 and ~ molecular weight range and the convor~ion of w ch streams or LLacticns thereof to alcchols 2~2(~,~

andVor ethers can also prcvide pruducts useful as solvents and blending stocks for gas~line.
The catalytic hydration of olefins to provide alcoh~ls and ethers is a well-established art for the production of the IPA and DIPE and is of significcu,t couu~ial importance.
Representative olefin hydration Fro~esses are d;crlosed in U. S.
Patents Nos. 2,262,913; 2,477,380; 2,797,247; 3,798,097;
2,805,260; 2,830,090; 2,861,045; 2,891,999; 3,006,970; 3,198,752;
3,810,848; 3,989,762, among okhers.
Olefin hydration employing zeolite catalysts is also known. As disclosed in U. S. Patent ~o. 4,214,107, lower olefins, in particular prqFylene, are catalytically hydrated over a crystalline alumunosilicate zeolite catalyst having a silica to alumina ratio of at least 12 and a Constraint Index of from 1 to 12, e.g., acidic Z5M-5 type zeolite, to provilde the ccrrrspcrLing alcohol, essentially free of ether and hy~h~rraan by-product.
The production of eth r from sec~nlary alcohols su~h as isopropanol and light olefins is known. As disclosed in U. S.
Patent No. 4,182,914, DIPE is prcduced from IP~ and propylene in a series of operations employing a ~LL~u~ly acidic cation exchange resin as cat~lyst. Re oe ntly, Frocc~se~ for the hydration of olefins to provide alcchols and ethers using zeolite catalyst have been disclo6ed in U. S. patent applications Serial Nos. 139,570, 139,567, 139,565, 139,569, 139,543 and 139,566.
Adapting available refinery feedstock to simultanecusly produce the above oxyg2nates as octane enh~ncers can involve tw~
different etherification procrsses, i.e., iso-olefin etherification to give ~ethyl tertiary aIkyl ethers and prcpylene hydration and e~herification to give ~ and IP~.
A~roroUrgly, a challenge is pr~vided to explore thse prrfoCces to discaver how they may be integrated in a rEulxer m~re benef~cial to the production o~ high octane gacoline.

~ V h wo go/11267 PCr/USgO/0147 i.

It has been discovered that the processes to manufacture tertiary alkyl ethers such as MIEE and T~ME and prrrCsses to manufacture di-isopropyl ether DIPE can be integrated in an overall prooess to produce high octane gasoline rich in these ethers. The integration is ac~ieved in a combined separation step where the effluents from both etherification zones are p~CCDd to a common water wash tower for y aration of an organic phase containing C3+ hydrcc~riY~s and oxyy~nates including C4 ethers. The aqueous phase from the water wash tower which contains methanol and isoprcpanol is recycled to the DIPE
etherification zone while the organic phase is debutanized to produoe high octane gasoline rich in ethers and an overh~ad c~mprising C4-hycroc æbons. The w~ater wash step allows larye excess quantities of methanol to be used in the M~EE
etherification step withcut recycle. Accordingly, the invention advantagecusly employs a common water washing step and common debutanizing step in the manufacture of tertiary alkyl ethers and D~E. The commcn water wzshing zone utilizes the DIPE
etherificatian zone water feed for the water washing prooess.
Mcre particularly, the present invention provides an integrated continuous prccess for the producticn of C4+ ether rich gasoline, the pro oe ss co~prising the steps of: contacting a fresh mixture of o ~ethanol and C4+ hydrccarbon feedstock rich in tertiary olefins with an acidic etherification catalyst in a first etherification zone un~er tertiary olefin etherification conditions whreby an eth#rificatic~ effluent sh~o~ oontaining methyl tertiary alkyl ethers, unreacted ~ethanol and C4+ hydrGc3Ito~s ~ p~cduced. Fresh C3 olefinic hydIocalbon fee~stock and an aquecus fraction containing orrezcted ne*hanol and ioc{rcpanol ~c o~ntacted in a second etherification zone with acidic olefin hydration catalyst under olP~ins hydration and etherification oonditions whereby an e~flunt gtream co~ta~ning oxygenates oo~prising di-isoprcpyl 2 ~ t ~
' W O 90/11267 PCr/US90/01479 ether, methyl isopropyl ether and isoprcpanol is produoed. m e first and second etherification zone effluent streams are passed to a common water washing zone and the streams are separated therein to prcvide an organic fraction ~ C3+
hydroc~rbcns and C4+ ethers plus the aqueous L~-~ction unreacted methanol and isop1opanol. Gasoline boiling range hydroc~rbons rich in C4+ ethers are reocvered from the organic fraction.
m e process further comprises separating the DIPE
effluent stream prior to water washing and recycling a major portion of the unreacted C3 d efinic hydrccar}on, water and isopropanol components theraof to the DIPE etherification zone while passing the oxygena~C cncpcrents thereof to the w~ ng zone.
Anc*her er~li~ of the present ir~vention cC~ric~c an int~rated oontinuous process for the pm~2ction of C5+ ether rich gasoline ccanprising the st~s of: oontacting a fresh mix~re of e~cs lower aL~canol, a fi~;t C4+ iydr~r~on feedstream rich in tertiary olefins and a seccnd fe~st~ camprising di-isc~l ether and ~s~d lower aL~nol with an acidic etherificaticn catalyst in a first etherificatil zcne under tertiary olefin etherificaticn o~itians w~ an etllerification effluent stream o~ tainir~ C5+ ethers and unreac~ed alkanol is pr~ced; separatir~ the efflue~t stre~n in a water wash t~wer in contact with water feeds~e~= to prcvide an or~nic fraction oontaini~ C4+ ~ s and C5+ ethers and an aquecus Fbase ca~rising water ar~ ~cted lcwer alk~nol:
- separating said aqueous pbase ky distillation in a~ibination with a distillaticn feedstre~ o~rising di-iscp~l ether w~y - 30 an c~Terhead stream cc~rising the seccnd f~ and a bott~
stream o~taini~g water is p~ced; introducing the bottam stream and C3 olefinic Iydr~ into a secand eth~ification zane in cc~tact with acidic olefin hy~raticn catalyst urx3er 2~27~'1 olefins hydration and etherification con~itions w~n~by an effluent stream oontaining di-isoprqpyl ether oomprising said distillate feedstream is produced.
In the draw mys, Figure 1 is a general block flow S schematic of the present process.
. Figure 2 is a flow schematic of a preferred e=todimeDt of . the p mcess of this invention.
Figure 3 is a flow schematic of an o-tyxl~D~Lt of the present invention without methanol feed to the DIPE
etherification zone.
In the preferred embodl~ent of the instant invention the principal components of known prooesses are ir~ rated in a manner pmviding a highly advantageous and surprising advnncement in refinery technology leadiny to the pmduction of high octane gasoline blendiny oomponents. Xna~ pra esmes are oonibined in a unique oonfiguraticn that provides erh ~ ment of the performance ~, of rponent proc~ses as well as achieviny su~prising advantages for the integrated pmoess. The pmcesses integrated inclutle - etherification to pmduoe low~r aLlcyl tertiary aL~cyl eth~s such as MrBE (methyl tertiary hltyl ether) and q~ME (tertiary alTyl D~yl ether) and C3 olefins l~raticn and eff~ification to .~ produce alcohols and e~rs s~ch as I~E, IPA ard me~yl - is~l ether.
, ~ I~wer aLlcyl in the present inventian refers to Cl-C3 aLlcyl derived fmm e~erification using lower aL~nol such as . metbanol, ethanol or i ~ anol. Tertiary alkyl refers to C4-C5 ,, tertizry alkyl groups derived from t~e etherificaticn of tertiary ,~ olefins. The te~m oxygenates or oxygenate as used hrein cYrFrises singularly or in oombination Cl-C8 lower alipatic, acyclic aloohols or alkanol and symmetri~a1 or u:E3~mmetriral C2 Cg ether;s.
Ihe Fl~x~ess o~ the present inventicn is dil~x:ted to ' ,, , ,~ , S

2 ~ ¢' 3 r~ ~
., W O 90/11267 PCT/US90/01479 maximizlng the utilization of C3+ refinery streams for the production of those gasolLne range oxygenated species, or oxygenates, known to exhibit high octane nu~bers which are useful for gzsoline product blending. Table 1 lists those oxygenated S species of partlcular interest as products of the present m vention.

q~bl~
Product Ele ~ Octanes ~- ~yS~ t r Methyl Terti æ y E~yl Ether ~Mr3E) 1~O lOO
Di-isoprcpyl ether (DIPE) lO9 99 Iscpropyl alcohol (IPA) ll6 95 Iscpropyl Tertiary Eutyl Ether (I~ ) ll6 In the preferred erbodi~ests of this i~vention, methanol is reacted with C4+ olefLnic hylh3x~u1hon feedst~ck such as FCC unsaturated gas plant conta~n m g olefins, p æ ti~l æly iso-olefins, to produce ~ethyl terti æy butyl ether In the reaction, ~e~hanol or lower alkanol ~ generally present in a stoichiometric excess amount between 1 and lO0 peroent, preferably 3%, based upon isdbutylene. The presence of a s ~ tial excess of me*hanol i5 a feature of this invention which allcws inrreaed conversion of tertiary olefins. The separation of une~eKted nethanol is achieved cc~veniently through the unigue co~tribution of this invention as described hereinafter.
~iLmol may be readily bbkained LLU~ ccal by gasification to synthesis y and conversion of the synthesis y to me*hanol by well-established indhstri~l F=XIY#E=eS. As an alternative, the n~*hanol m~y be obkained from natural y by other oonventional pcocesses, ~uch as steam reforming or parti31 oxldbtlon to r ~ e the m bercedl~te syr. y . Cru~e rr~ hano1 ~ron s f~l V ~ ~
W O gO/~1267 PCT/US9~0~7 such processes usually contains a significant a~ount of water, usually in the range of 4 to 20 wt%. The etherification catalyst employed is preferably an ion exchange resin in the hydrogen form; however, any suitable acidic catalyst may be e~ployed. Varying degrees of succ~ss are obkained with acidic solid catalysts; such as, sulfQnic acid resins, phDsphoric acid modified kieselguhr, silica alumina and acid zeolites. Typical hydr~o~rbon feedstock materials for etherification reactions m clude olefinic streams, such as FCC
light naphtha and butenes rich in iso-olefins. These aliphatic ; streams are produced in petroleum refineries by catalytic cracking of gas oil or the like.
m e reaction of methanol with isobutylene and isoamylenes at mcderate conditions with a resin catalyst is kncwn technology, as provided by R. W. Reynolds, et al., The Oil and_Gas Journal, June 16, 1975, and S. Pecci and T. Floris, y~bal_Process m, Deoe~ber 1977. An article entitled '~DCEE
and IAME - A Gbcd octane Eoc6ting Ccmbo," by J.D. Chase, et al., The Oil and Gas Journal, April 9, 1979, pages 149-152, d~c~5e5 the technology. A preferred catalyst is a bifunctional ion exch~nge resin which etherifies and isomerizes the reactant streams. A typical acid catalyst is Am~erlyst 15 sulfonic acid resin, a prodNct of Rd~m and Hb3s Corporation.
M~E is known to be a high octane ether. Ihe article by J.D. Chase, et al., O;l and Gas Journal, A~ril 9, 1979, discuoses the advantages one can achieve by us m g these materials to enhance gasoline octane. The octane blending number of MI~E
whEn 10% is added to a base fuel (RiO = 91) is about 120. ~or a fuel with a low motor rating ~MhO = 83) octane, the blending vzlue of MIEE at the 10% level is about 103. ~n the other hand, for an pR~O) of 95 octane fuel, the blending v lue of 10% MI~E is about 114.

, W O 90/1126~ PCT/US90/01479 Pr w esses for produc mg and recoverLng MIBE and other methyl tertiary alkyl ethers from iso-olefins are known to those sXilled in the art, such as disclosed in U.S. Patents 4,544,776 (Obterburl, et al.) and 4,603,225 (Colaianne et al.). In the prior art various suitable extraction and distillation techniqyes are knLwn for recovering ether and hydrocarbon straams from etherification effluent. EXtraction and distillation techniques are used to recycle unreacted methanol. These techniques, as practioe d in the prior art, are economically burdensome upon the Ml~æ prooess involving, as they do, the extraction and distillation of aqueous solutions. As a oonsequence of the oost ~crciated with the aqueous extraction and distillation of aqueous solutions experienced in the process of s~parating unreacted methanol prior art proresses tend to sbarply limit the amcunt of exoess methanol added to the MIEE etherification reaction. A ccmpromise is struck ketween the ccst of nEthanol separation and thP favorable effect of excess me*hanol on the ccnversion of isoolefin to tertiary ethers. The nEthod of the present obviates that oompromise.
The olefins hydration and etherification process inkegrated in the present invention embcdies the reaction of prcQylene with water catalyzed by stlw~ acid to form i90prqp~ool. Reaction continucs ~n the hydration zone to form di-iscpropyl ether or, when a lower alochol is pr~sent such as me*hanol, mekhyl isoprc~yl ether is also formed. Ihe cperat mg oonditions of the olefin hydration prccess here~n are nat es~ec;~lly critical and include a temperature of from 100 to - 450C, preferably from 130 to 220 & an~ most preferably from 160 to 200C, a pressure of from 790 to 24230 kPa (100 to 3500 p6i), preferably r,~ 3550 to 13890 kPa (500 to 2000 psi), a water to olefin mole ratio of fnom 0.1 to 30, preferably frsm 0.2 to 15 and ~u~L preferably from 0.3 to 5.

2~27a~1 m e olefin hydration prooess of this invention can be carried out under supercritical dense phase, liquid phase, vapor phase or mixtures of these phases in batch or c=rtinuoos manner using a stirred tank reactor or fixed bed flow reactor, e.g., S trickle-bed, liquid-up-flow, liquid-down-flow, clurter-corrent, crrcurrent, etc. Reaction times of Ll~ 20 minutes to 20 hcurs when cperating in batch and an LHSV of from O.l to lO when operating continuously are suitable. It is generally preferable to recover any unreacted olefin and recycle it to the reactor.
The catalyst employed in the olefin hydration and ethrification operations is any Lewis acid but preferably shape=selective acidic zeolite. In general, the useful catalysts embra oe two categories of zeolite, namely, the intermediate pore size variety as represented, for example, by ZSM-5, which p~csess a Constraint Index of greater than about 2 and the large pore variety as represented, for example, by zeolites Y and ~eta, which possess a Constr~int index no greater than about 2.
Preferred catalysts include Zeolite ~eta, Zeolite Y, Z5M-5, ZSM-35, and M~M-22. Eoth varieties of zeolites will possess a framework silica-to-alumuna ratio of greater than about 7.
A convenient measure of the extent to which a zeolite prcvides controlled aocess to molecules of varying sizes to its internal Etructare is the aforementicned Crnstraint Index of the zeolite. A zeolite which provides relatively restricted ac oe ss 2s to, and egress from, its internal ctructune is characterized by a relatively ~igh value for the Ccnstrain Index, i.e., above about 2. on the other hand, zeolites which provide relatively free access to the internal zeolitic ctnocture have a relatively low vzlue for the Ccrstraint Index, i.e., about 2 or less. ~he method by which Constraint Index is deterrined is described fully in U.S. Patent No. 4,016,218, to which reference is made for tails of the me*hcd.
Ihe large pore zeolites which are useful æ catalysts - 2~2~7~
~ `, W o 90/11267 PCT/US90/01479 ; in the process of this invention, i.e., those zeolites h~ving a j Col straint Index of no greater than about 2, are well known to the art. Representative of tbese zeolites are zeolite Eeta, zeolite X, zeolite L, zeolite Y, ultrastable zeolite Y ~USY), j S dealuminized Y (Deal Y), rare earth-exlhzrg~ zeolite Y (REY), rare earth-exchangel dealuminized Y (RE Deal Y), mordenite, ZSM-3, ZSM-4, Z5M-12, ZSM-20, and ZSM-50 and mixtures of any of the foregoing. Although zeolite B~ta has a Constraint Index of about 2 or less, it should be noted that this zeolite does not behave exactly like other large pore zeolites. ~cwever, zeolite ~eta d oes satisfy the require ents for a catalyst of the present invention.
Zeolite Eeta is descrih~d in U.S. Rei~cnp Patent No.
28,341 (of original U.S. Patent No. 3,308,069), to which reference is made for de~ c of this catalyst.
Referring now to Figure 1, a general block flow schematic of the process of thiC invention is preYested. Ihe major unitc of the prccess mclude the DIPE etherification section A
containin3 acidic catalyst, the MIBE etherification section B
contlining acidic catalyst, water wash tower C and debutanizer D.
A hydrlc~rbon feedstock 110 ccrrdLhing propylene is passed to the Dl~ etherification zone A while ~x oess lower alcbhol such OE
methanol is passed via conduit 115 to MI~E etherification zone B
in conjunction~with a hydrocarbon feedstock 120 rich in C4+
isoolefin_. Water for zone B olefins hydration is transferred via stream 125 to zone A OE part of the aquQous pbase from water wash tcwer C. Ihe water transfer system from zone B to zone A
in~ludes water purge line 126.
The etherification re2ctions in zones A an~ B are carried out under Xnx~n conditions OE previously described here~n. Ihe effluenk6 130 an~ 135 from the etherification zones are p ~ to tbe common water wash tower C for eKtraction with water intr~cYd via 140. The ag!~eous phase from C crnt~

2 0 2 7 ~ r~

unreacted methanol from B and ~ rqpanol from A i_ pHssed ta A
as ncted. The o ~ c ~ e from C crneainong DIPE, C4+ ethers and unreacted hydrocarbcos from A and B is passed via stream 145 to debutanizer D for separation. An cverhead streæm 150 containing C - hydrocartoos pluc a kottoms stream 155 oomprtcing C5+ gasoline containing ethers including DIPE and MIBE exit from the dekutanizer. ~he gasoline stre~m may also oantain methyl isc~mpyl ether, ~ and other ethers of C4+ isoolefins.
Referring r~w to Figure 2 a flaw s~ematic of a preferred ~iment of the process of this invention is preser~d.
Methanol 210 and C4+ hydrocartcn feedsto~c 215 are int~
into an etherification zone 220 containing a solid acidic catalyst suc~ as Anberlyst ~5. Methanol is in a stoichianetric excess a~t npared to the isaolefin oant~t of the C4+
~ydro~cn feedsto~c but typically betwe~ 1 and 10% in exoess.
qS~e etherification is carried out ur~er kna~n etherificaticn ocs~itions betwe~ a te~;erature of 60C and 125& and th~
efflu~nt 225 canprising MrE3E, ~ME, unreacted methar~l and unreacted C4+ hydr~r~ns is fed to a water wash tower 230, preferably after cooling.
A hydrcx~u~cn feedstock 235 rich in propylene is passed to an olefins hydration and et~erification zone 240 which preferably oontains zeolite Beta catalyst. HydratiQn and etherification is carried out under known oanditions in contact with water introdoced as a ccGponent of the aqueous pbase 245 crntai m ng me*hanol and iscprop mol separated frnm water wzsh tower 230. The effluent ~rom the DI~E etherification zone 240 is separhted in a high pressure separator 250 and water and isGp:opanol c~rponents of the effluent are recycled 255 to the etherification reactor. A~H~r cooling, uneeactcd C3 hqdr=c2rbco~ are fed via 260 to a high pressure flash evaporator 265 and Eepor~ted at a pressure preferably less than about 350 XPa low~r than the etherification zcne 240 pressure. A major 7 ~ , W O 90/~1267 PCT/VSgO/0147g portiorf of the unreactedf C3 hylrccarbcn c~nFDnent of the effluent stream is preferably re-ccmpressed 275 and recycled 270 to the hydration and etherification zone 240. The kok*om fraction 280 of the flash evaporator which contains ethers from 240, isoprcpanol and some C3 hycrccarbon is cooled an~ passedf to the water w3sh tower 230.
From the wa~r wash tower 230 eXlt the previously noted a ~ s phase 245 andf an o ~ ic phase 290 which contains C3+
hydr~cartons and ethers frcmfkoth etherification zones 220 and 240 comprising DIPE, N~8E andf T~ME. In the Dlt~ etherification reactor exress mefthanol frc~fthfe MIEE reactor is nrstly con~erted to methyl iscpropyl ether. Ihe organic pbase is separated in debutanizer 295 to produce C4-hydr~carbcns 296 and high octane gasoline 297 rich in C4+ ekhers.
The process of the present inventiQn uniquely llCDS only one debutanizer to stabilize DIPE prodLcts and ~Ethyl tertiary alkyl ether prclducts. Also, the prooess uniquely uses one water wash tower to absorb etherification excess ~ethanol and DIPE
pr~cess isopropyl alcohol ~yln~xh~c in*o the Dl~ water feed.
As described hereinlfcer for another ~h~diment of the inventicn, it has been discovered that cycling unreacted lower alkanol to the DIPE reactor can be avoided by carrying out water washing of the effluent fm m tertiary olefins etherification immedia~ly dcwnstrean of the etherificatian zone and separating the aqueous pbase by distillation in a co~mon distillation tower for bcth the pr~duct of DI~E etherification and unreac*ed lcwer alXanol. The aqueous distillate is transferred to the DIP.E
etherification zone as reactant in that process. The ether rich qp~^line pr~duct is oollected by separating the organic pbase ~u~ the water wash tcwer.
Referring now to Figure 3, the other ea}xX~u~ent of the ins*ant invention is presentod wherein no D~ymol from the MI3E
e*herification zone is sen~ to the DIPE etherification zQne~ In W O 90/11267 Pcr/usso/ol47s ~

this variation, the formation of methyl isopropyl ether in the .
DIPE etherification zone is avoided. Fecdstre~m 310 containing lower alkanol s~ch as methanol and C4+ hydrDcarbon is fed to ~19E
etherification zone 320 in contact with acidic etherification cat~lyst as d~crr~bed hereinkefore. The effluent stream 330 from the MI9E zone is passed to water wash column or C~r~r~tor 340 and separated in contact with water wash feedstreIo 350. Ihis fe~istDca= serves to provide bcth wa~ for the physical separation of the components as required in the process and as the required reactant in the DIPE etherification ZQne. Ihe organic phase 360 is fed to debutanizer distillation fractianator 370 where an overhead stream 380 ccntaimng C3 and C4 Iydro~s is separated. l~le battam effluent stream 390 from the debutanizer c~nprises ether-rich gas~line. The aqueous phase 305 fmm water wash column 340 o~nt~irdng water and unreacted ~thanol L~ the etherification zone 320 is passed to distillation seFarator 315. A battam stream 325 oDntair~ing water and is~yl alcohol (IPA) ic separated from se~arator 315 and trar~cferred to l~rPE etherification zone 335 via corx~uits 336 and 337 and ~nrp 338. C3 Iydr~tcn fe~eom 345 is passed to etherification zone 335 in contact with acidic catalyst as cl~ibed herein before. q~le effluent 355 fmm zone 335 is passed to ~arator 365 for separation of a ~ttom stre~ 339 oant~ng water and isc~yl alcdlol ~i~ is trar~cferred to zone 335 ~y ~mp 341. Ihe overhead stream 375 cor taini ng water, C3, IP~ a~ DI~ is Fassed to distillation separator 385. An orverhead stream 395 c~prising C3 ~ is ~arated and a bottam stream 396 ca~rising C3 ~yd~s, water, I~ and 1~:
is passed to distillation separator 315. F~am se}?arator 315 an ~ ;tream 398 is separated c~taining C3 hyd~s, 1~, IP~ and l=re3c~d ~thar~l. Oanduit 400 ~eoted to a~duit 325 can be used for blow-dawn.

2G2r~rl~
' ~J'~ WO 90/11267 PCl'tUS90/01479 examples and eni~iiD~s, there is no int~t to limit the irlventive corx~ept exoept as set for~ in the follo~ring cl~.

Claims (22)

CLAIMS:

1. An integrated continuous process for the production of C4+ ether rich gasoline comprising the steps of:
(a) contacting a fresh mixture comprising excess C1-C8 lower alkanol and C4+ hydrocarbon feedstock rich in tertiary olefins with an acidic etherification catalyst in a first etherification zone under tertiary olefin etherification conditions to produce a first etherification effluent stream containing lower alkyl tertiary alkyl ethers, unreacted lower alkanol and C4+ hydrocarbons;
(b) contacting fresh C3 olefinic hydrocarbon feedstock and an aqueous fraction containing a lower alkanol and isopropanol in a second etherification zone with an acidic olefin hydration catalyst under olefins hydration and etherification conditions at a temperature of 50° and 300°C to produce a second etherification effluent stream containing isopropanol and oxygenates comprising di-isopropyl ether and lower alkyl isopropyl ether;
(c) passing the first and second etherification effluent streams to a water washing zone and separating the streams to provide an organic fraction containing C3+ hydrocarbons and C4+
ethers and an aqueous fraction containing unreacted lower alkanol and isopropanol; and (d) recovering gasoline boiling range hydrocarbons rich in C4+ ethers from the organic fraction.

2. The process of claim 1 further comprising separating the second etherification effluent stream into one stream comprising unreacted C3 olefinic hydrocarbon, water and isopropanol, which stream is recycled to the second etherification zone, and another stream comprising the oxygenates, which stream is recycled to the washing zone.

3. The process of claim 2 wherein the C3's are separated by distillation at a pressure less than the pressure of the second etherification zone.

4. The process of claim 3 wherein the pressure is 350 kPa less than the second etherification zone.

5. The process of claim 1 wherein the water washing zone comprises a water washing tower.

6. The process of claim 1 further comprising passing the organic fraction from step (c) to a debutanizer to separate into a C4- hydrocarbon overhead fraction and an ether rich gasoline bottom fraction.

7. The process of claim 1 wherein step (b) olefins hydration catalyst comprises acidic shape selective zeolite.

8. The process of claim 7 wherein the zeolite is selected from intermediate pore size or large pore size zeolites having a Constraint Index of 2 to 12 or zeolites possessing a Constraint Index of 2 or less.

9. The process of claim 7 wherein step (b) hydration catalyst is selected from zeolites ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-38, Beta, X, L, Y, USY, REY, Deal Y, Re Deal Y, ZSM-3, ZSM-4, ZSM-12, ZSM-20, ZSM-50, MCM-22 and sulfuric acid resins.

10. The process of claim 1 wherein the olefins hydration and etherification conditions comprise temperature between 110 to 200°C.

11. The process of claim 1 wherein the lower alkyl tertiary alkyl ethers comprise methyl tertiary butyl ether and methyl tertiary amyl ether.

12. The process of claim 1 wherein the excess alkanol comprises a large stoichiometric excess of alkanol based on tertiary olefins in the C4+ hydrocarbon feedstock.

13. The process according to claim 12 wherein the stoichiometric excess is between 1 to 100 wt%.

14. The process according to claim 13 wherein the stoichiometric excess is 3 wt%.

15. The process of claim 1 wherein the tertiary olefins comprise isobutylene and isoamylene.

16. The process of claim 1 wherein step (a) acidic etherification catalyst is selected from zeolites ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-38, Beta, X, L, Y, USY, REY, Deal Y, Re Deal Y, ZSM-3, ZSM-4, ZSM-12, ZSM-20, ZSM-50, MCM-22 and sulfuric acid resins.

17. The process of claim 1 wherein step (a) is conducted at a temperature between 60 and 125°C.

18. An integrated separator means for the separation of the effluent streams from di-isopropyl ether manufacturing zone and from methyl tertiary alkyl ether manufacturing zone in the production of ether rich high octane gasoline, comprising in combination:
water wash means for separating water soluble components in an organic stream containing C4+ ethers receivable connected to receive water and effluents from first and second reactor means;
first reactor means for containing methyl tertiary alkyl ether manufacturing zone operatively connected to the water wash means;
second reactor means for containing di-isopropyl ether manufacturing zone operatively connected to the water wash means;
first conduit means, connected to the water wash means, for withdrawing aqueous phase therefrom; second conduit means, connected to the water wash means, for withdrawing organic phase therefrom.

19. The process of claim 1 wherein the lower alkanol is selected from methanol, ethanol and isopropanol.

20. The process of claim 1 wherein the C5+ ethers comprise di-isopropyl ether and lower alkyl tertiary alkyl ethers.

21. The process of claim 20 wherein the lower alkyl tertiary alkyl ethers are selected from methyl tertiary butyl ether, methyl tertiary amyl ether, ethyl tertiary butyl ether and isopropyl tertiary butyl ether.

22. The process of claim 1 wherein the step (a) lower alkanol comprises isopropyl alcohol comprising the reaction product of the step (d) etherification zone.