CA2018524A1 - Process for light olefins hydration and mtbe production - Google Patents

Abstract

PROCESS FOR LIGHT OLEFINS HYDRATION AND MTBE PRODUCTION

Abstract of the Disclosure A process is disclosed for converting C3 and C4 olefins to high octane ethers and alcohols. The invention incorporates C4 tertiary olefin etherification to produce lower alkyl tertiary butyl ether in a first etherification step under mild conditions and olefins hydration using zeolite catalyst in a second sequential step to produce other oxygenates. The invention comprises an integrated process for the conversion of hydrocarbon feedstock comprising C3-C4 olefins containing isobutylene to high octane alcohol and ether, including lower alkyl tertiary butyl ether, comprising the steps of: introducing the feedstock and lower alkyl alcohol to an etherification zone under isobutylene etherification conditions in contact with acidic etherification catalyst and recovering lower alkyl tertiary butyl ether and unreacted hydrocarbons comprising propylene and butene. The unreacted hydrocarbons and water are passed into an olefins hydration zone in contact with acidic hydration catalyst such as zeolite Beta under olefins hydration and etherification conditions whereby high octane gasoline boiling range C3-C8 acyclic aliphatic oxygenates are produced. In a preferred embodiment the lower alcohol comprises methanol and methyl tertiary butyl ether (MTBE) is produced.

Description

- ~OCESS FOR LIC~T OLE~IN~ ~lCRAII~ C~ rn~ W~

This invention relates to an intbgrated process for the conversion of light olefins to alcohols and ethers, including methyl tertiary butyl ether. More particularly, the mvention relates to the catalytic hydration of light olefins such as C3-C4 hydrocarbons to oxygenates in conjunction with the conversion of isobutylene to lower aLkyl tertiary butyl ether. ~he products of the integrated process are useful as high octane blending stocks for gasoline. -In recent years, a major technical challenge presented to the petroleum refining industry has been the reqpirement to establish alternate processes for manu~acturing high octane gasoline in view of the regulatory requirement to eliminate lead additives as octane erhan oe rs as well as t;he development of more efficient, hi~her ccmpression ratio gasoline engines requiring higher octane fuel. To meet these reguiremrnts the industry has developed non-lead octane boosters and has reformulated high octane gasoline to incorporate an incre~sel fraction of aromatics. While these and other approaches will fully meet the technicAl rrguirements of regulations requiring elimlnation of gasoline lead aA~itives and allow the industry to meet the burgeoning market demand for high octane gasoline, the economic impact on the cost of gasoline is significant. Ascordingly, workers in the field have intensified their effort to discover new processes to manufacture gasoline pro*ucts required by the market place. One important focus of that research is processes to prc*uce high octane gasolines blended with lower aliphatic alkyl ethers as octane boosters and supplementary fuels. C5-C7 methyl alkyl ethers, especially methyl tertiary butyl ether (MTBE) and tertiary a~yl methyl ether (I~ME) have been found particularly useful for enhancing gasoline octane. Therefore, improvements to the prnresses related to the production of these ,' ~', ~,~, . . .

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c~h~r~ ~r~ r~ . L~p~r~ce ~nd su~ u~tial challenge co r~a~r~. ~orxæ-s in ~ne petroleu~ refilLhng arts.
It is well kncwn that isQbutylene may be reacted with methanol over an acidic catalyst to provide methyl tertiary butyl ether (MIEE) and isoamylenes may be reacted with methanol over an acidic catalyst to produce tertiary amyl methyl ether (IAME). The reaction is a useful preparation for these valuable gasoline octane echanctrs and is typical of the reaction of the addition of primary alcohols to the more reactive tertiary alkenes of the type ~ ~ under mild conditions to form the corresponding tertiary alkyl ethers of primary alcohols. me feedstock for the etherification reaction may be taken from a variety of refinery process streams such as the unsaturated gas plant of a fluidized bed catalytic cracking ~peration containing mixed light olefins, preferably rich in isc~utylene. Light olefins such as propylene and isc~ers of butene other than isc~utylene in the feedstock are ess~ntially unreactive ~cward alcohols under the mild, acid catalyzed etherification reaction conditions employed to produce lower alkyl tertiary butyl ether.
Lower molecular weight alc~hols and ethers such a isopropyl alcc~ol (IPA) and diiscpropyl ether (DIPE) are in the gasoline boiling range and are known to have a high blending octane number. In addition, by-product prcpylene from which IPA
and DIPE can be made is usually available in a fuels refinery.
The petrochemicals industry also pro*uc s mixtures of light olefin streams in the Cz and C7 mol~ ar weight range and the c~nversion of such streams or fractions thereof to alcchols anq/or ethers can also provide products useful as solvents and blending stocks for gasoline.
The catalytic hydration of olefins to prcvide alcohols and ethers is a well-established art and is of significant commercial importance. Representative olefin hydration processes are disclosed in U. S. Patents Nos. 2,262,913; 2,477,380;

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j 2 2,?97,247; 3 798,097: 2!805,260: 2.830,090: ~,86~ 045; ~,~91,999;
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Olefin hydration employing zeoLite cataLysts is knawn.
As disclosed in U. S. Patent No. 4,214,107, la~er olefins, in 5 particular propylene, are cataLyticaLly hydrated wer a crystalline al~ninosilicate zeolite catalyst having a silica to aLwnina ratio of at least 12 and a Constraint Index of frc~m 1 to 12, e.g., acidic ZSM-5 1~pe zeolite, to prwide the corresponding aLcohol, essentially free of ether and hyd~on by-product.
Ihe production of ether fram secondary alcohols such as ~-isopropanol and light olefins is lcn~n. As disclosed in U. S.
Patent No. 4,182,914 di-isop~rl ether (DIPE) is produced frc~n isopropyl alcohol (IPA) and propylene in a series of operations employing a strongly acidic cation exchange resin as catalyst.
Reoe~tLy, processes for the hydration of olefins to prwide alcohols and ethers using zeolite catalyst have been disclosed in patent applications Serial Nos. 139,570, 139,567, 139,565, 139,569, 139,543 and 139,566.
The present irlvention prwides a process for converting 20 C3 an~ C4 olefins to high octane ethers and alcohols, leading to important advantages not heretofore a~hieved in the econamic utilization of C3 and C4 olefins to produce high value gasoline octane ~. ~e invention incorporates C4 tertiary olefin etherification to produoe lchrer aLkyl tertiary butyl ether in a 25 first etherification step under mild conditions and nwel olefins hydration using zeolite catalyst in a second sequential step to produoe other o~enates. The inventic~ camprises an integrated process for the conversion of hydr~arbon feedstoc~c canprising C3-C4 olefins containing isobutylene to high octane alcohol and 30 ether, including lawer alkyl tertiary bu~rl ether and the steps ;
of: introducing the feedstoc~c and lcx~er alkyl alcohol to an etherification zone under isobutylene etherification conditions in contact with ac:iclic etherification catalyst and recovering ~:
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lower alkyl tertiarv butvl ether and unreacted hvdrocarbons c~p~isi~ P~F~ ~r3 ar~ b~t.~r2.. ~ d ~ X~-~'r.~J~
water are passed into an olefins hydration zone in contact with acidic hydration catalyst such as zeolite Beta under olefins s hydration and etherification ~onditions whRreby high octane gasoline boiling range C3-C8 acyclic aliphatic oxygenates are produced.
More particularly, the invention esccmpasses an integrated process for the conversion of hydroc~rton feedstock comprising C3-C4 olefins containing isabutylene to alcQhol and ether, including lower alkyl tertiary butyl ether, comprising the stepe of: introducing the feedstock into a C3-C4 hydrocarbon fractionator or splitter and separating the feedstock into effluent streams comprising a C3 stream and a C4 stream containing isokutylene. me C3 efflllent stream and water are passed to an olefins hydration zone in contact with acidic hydration catalyst under olefins hydration and etherification conditions whereby di-isopropyl ether and isopropyl alcohol are pr~duced. The C4 effluent stre~m and lower alkyl alcohol such ~s methanol are passed to an etherification zone under isobutylene etherification conditions in contact with acidic etherification catalyst and lower alkyl tertiary butyl ether such as MIEE and unreact3d 1- anq~or 2-~utenes are reccver~d. The unreacted butenes and water are introduced into an olefins hydration zone in contact with acidic hydration catalyst under olefins hydration and etherification conditions whereby di-butyl ether and 2-butanol are produced.
In the drawings, Figure 1 is a general flow schematic of the process of this invention.
Figure 2 is a flow schematic of a preferred embadiment of the instant inven~ion. '~
In a preferred embodiment of the instant invention the principal components of known processes are inte B ted in a 2 ~

r pr~vidina a hiqh;ly adv~n~ge~ a~d surpris ~q ~ ~nr~m~nt m ~sf'~ chnc'o-~r leading ~ e ~r~t o~ hioh ~cL~
gasoline blending components. Known prnr~ccp~ are combined in a unique oonfiguration that provides enhancement of the performance of component prooesses as w211 as achieving suxprising adNantages for the integrated prccess. The prooesses integrated include etherification to produce lower alkyl tertiary alkyl ethers such as MIBE (methyl tertiary butyl ether) and other tertiary butyl ethers and olefins hydration to produoe alcohols and ethers.
Olefin feedstock may be pro~uoed, in entirety or in part, by including a paraffins dehydrogenation ste~o in the process. Also a butanes isomerization step prior to paraffin dehydrogenation may be mcorporatel ln the process to increase iso~utylene oonoentration in the hydric~rton fe~dstream to the MIBE unit.
The prccess of the present i~vention is directed to maximizing the utilization of C3-C4 refinery streams for the -production of those gasoline range oxygenated species, or oxygenates, kncwn to exhibit high octane numbers which are useful for gasoline product blending. Table 1 list those oxygenated species of particul æ interest as products of the present invention.
Table 1 Pro*uct Blending Octanes '' :':'~
Research Motor Methyl Tertiary Butyl Ether (MrBE) 120 100 Di-isopr3pyl ether (DIPE) 109 99 Isopropyl aloohol (IPA) 116 95 ~utanol (2-BuOH) 110 97 Ethyl Tertiary Butyl Ether (ETBA) 118 105 30 Isopropyl Tertiary Butyl Ether 117 (IPIBE) ll~e ~rm oxygenates or oxyqenate as i~CPd herein comprises s~gu~2rly or in ccmb~q~t o.. Cl-~8 lower aliphatic, acy~iic alcohols or alkanol and symmetrical or unsymmetrical C2-C9 ethers.
S The general prooess of the present invention is illustrated by a simplified block flow diagram in Figure 1 showing the relationship of the central unit processes of the invention and the management of feedstock and products. moSe central unit processes ~lprise an isobutylene etherification 10 unit 110 and an olefin hydration and etherification unit 120. The hydroc æbon feedstock to the isokutylene etherification unit is independent streams comprising essentially either C3 or hydrocarbons containLng light olefins such as propylene, 1-butene, 2-butene and, at least, isobutylene. Preferably, the feelsOock is rich in isobutylene. Alternatively, the hydrocar}on feedstock may be the combination of the foregoing C3 and C4 hydrooar}an streams co~taining light olefins. The streams may also contain paraffins such as propane and butane. In conjunction with the above hydrccarton feedstock, a lower alcohol feedstock 105 is passed or introduced into the etherification unit llO in an amount typically representing a stoichiometric excess based on isobutylene etherification. Lower alcQhol feedstock includes methanol, ethanol, n-propanol, 2-propanol, 1-butanol and 2-~utanol, alone or in a mixture. m e lower alcohol and isobutylene etherification reaction is carried out under acidic catalysis according to kncwn prooesses and under kncwn isokutylene etherification conditions. m e effluent frcm etherification unit 110 is separated by extraction or distillation, or a combination thereof, to produce and recover a lcwer aLkyl terkiary butyl ether product stream 120 and a stream 125 which oompriscG unreacted linear light olefins. The lower alkyl group of the tertiary butyl ether may be methyl, ethyl, propyl or butvl dep~nding on the lower alcohol feedstock l~Pd. In 2 ~ d /!1' ~e pr~~ rcion oxv~na~.a-re ta3~ frarn the consi~t~r~ of s~ G~, 2-~tarlol, di~ py' ~
di-butyl ether and methyl tertiary butyl ether, ethyl tertiary butyl ether, isopropyl tertiary butyl ether arr~ 2-butyl tertiary ~. -.
5 ~rl ether. The unreacted linear olefins of stream 125 ca~rise pr~pylene, l-hItene and~or 2-butene where the light olefin fe~stock is a mix~ure of C3 arYl C4 hyd~ons. ~en - :
independent C3 or C4 hydroca~on f~stock streams are used, ~u~reacted linear olefins in strean 125 are, correspondingly, 10 propylene or l-butene and~or 2-butene. The effluent stream 125 ;
may also contain unreacted lo~er alcohol and paraffins. Water is introduced }30 as reactant into olefins hydration and , etherification unit 122 in conjunction with effluent stream 125 and linear olefins are converted to oxygenates such as alcohols and ethers in contact with acidic catalysts under known condition. Products in effluent stream 140 can include di-isopropyl ether, isopropyl alcohol, dibutyl ether and 2-b~tanol. When the fee~sbock to 105 is C3 and C4 the products can also include isopropyl butyl ether. Optionally, alcohols in stream 140 can be recycled to etherification unit 120.
The term lower aIkyl as used herein refers to Cl-C4 alkyl groups and encrmpdsses all isomers thereof.
In the prcoess of the instant invention it has been discovered that the kncwn greater reactivity of tertiary olefins ;~
of the structure ~ G=CH2 compared to linear olefins of the structure RCH=CHR in etherification reaction with lower alcohols can be advantageously utilized to selectively etherify isobutylene in the presence of linear olefins to produce high octane lower aIkyl tertiary butyl ether. Then, in a sequential pro oess configuration, linear olefins are converted to high octane gasoline range oxygenates. Isobutylene etherification conditions are kncwn in the art and, in the instant invention, comprise mild condition of low temperature and high liquid hourly 0~8~24 spa oe valQ~itv, (T~.7~. Iscbu~l&-~ e~herificatio~ ~emperature can ~C f-! ~11 '^C io 150~ and prererat~ly between 50 and 125 &.
In the pre~erred =mbodimen~s of this invention, methanol is reacted with C3-C4 olefinic hyiroc æbcn feedstock such as FCC
unsaturated gas containing olefins, particularly iso-olefins, to produoe meT~hyl tertiary butyl eTher. In the reaction, methanol is generally present in a stoichiometric exr~cs amcunt between 1 and 10 percent, h~Pd upon isobutylene.
Methanol may be readily obtained from coal by gasification to synthesis gas and conversion of the synthesis gas to methanol k~7 well-establishad industrial processes. As an alternative, the methanol may be obtained frcm natural gas by other conventional processes, surh as steam reforming or partial oxidation to make the intermediate syngas. Crude methanol fmm 15 suc~h pro oesses usually contains a significant amount of water, ~- -usually in the range of 4 to 20 wt%. m e etherification catalyst employed is preferably an ion exchange resin in t'he hydrogen form; however, any suitable acidic catalyst may be employed.
Varying degrees of success are obtained wit~h acidic solid catalysts; such as, sulfonic acid resins, phos~horic acid m~dified kieselguhr, silica alumina and acid zeolites. Typical hydrao~rbon feedstock materials for etherification reactions include olefinic streams, such as FCC light na~htha and k~tenes rich in iso-olefins. ~hese aliphatic streams are pro~uced in petroleum refineries by catalytic cracking o~ gas oil or the like.
me reaction of methanol with isobutylene and isoamylenes -~
at moderate conditions with a resin catalyst is known technology, as provided by R. W. Reynolds, et al., The Oil and Gas Journal, 30 Juna 16, 1975, and S. Pecci and T. Floris, Eydrocarbon Prooessin~, December 1977. An articla entitled '~DrEE and TAME -A Good Octane Boosting Combo," by J.D. Chase, et al., m e Oil and Gas Jcurnal, April 9, 1979, pages 149-152, discusses the . ~ .

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technology~ A nnPferrP~ ca~ S ~ bi~xctional on ex~h~-~e r~ h.e~'l~xi~ r~ isomeri~ he re2ctant st~eams. A
typical acid catalyst is Amberlyst 15 sulfonic acid resin, a product of Rohm and Haas Corporation.
MIEE is kncwn to be a high octane ether. Ascording to Chase, supra, the octane blending number of MTEE when 10% is added to a base fuel (R~O = 91) is about 120. For a fuel with a low motor rating (M~O = 83) octane, the blending value of MIBE at .
the 10% level is about 103. On the other hand, for an (R+O) of 95 octane fuel, the blending value of 10% MIBE is about 114.
Processes for pr~duc mg and reoovering MIeE and other methyl tertiary alkyl ethers frGm isc-olefins are kncwn to those skilled in the art, such as disclosed in U.S. Patents 4,544,776 (Osterturg, et al.) and 4,603,225 (Colaianne et al.). In the 15 prior art varicus suitable extraction and distillation techniques ~-~
are known for reco~ering ether and hy~rocar}on strea~s fr~m etherification effluent.
The operating conditions of the olefin hydration process herein are not especially critical and include a temperature of from 60 to 450&, preferably frcm 90 to 220 & and most preferably frcm 120 to 200C, a pressure of from 670 to 24130 kPa (100 to 3500 psi), preferably from 3450 to 13790 kPa (500 to 2000 psi), a water to olefin mole ratio oP frcm 0.1 to 30, preferably from 0.2 to 15 and most preferably from 0.3 to 5.
m e olefin hydration pr~oess of this invention can be carried cut under liquid phase, vapor phase or mlxed vapor-liquid phase oonditions in batch or continuous manner using a stirred tank reactor or fixed bed flow reactor, e.g., trickle-bed, liquid-up-flcw, liquid-down-flow, counter-c~rrent, co,current, etc. Reaction times of from 20 minutes to 20 hcurs when operating in batch and an LHSV of from 0.1 to 20 when operating continuously are suitable. It is generally preferable to recover any unreacted olefin and recycle it to the reactor.

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The ca~a1vs~ ~-mln~ v~ h~ olef~n h~~at_~. æ~
e~l~ .~a~ G~d~i~f~ WhiG'~ ~r~ ~0~3cb~d seq~Antially dcwnstre~m of isQbutylene etherification operations is shape-selective acidic zeolite. In gene~iL, the usefuL catalysts embrace two categories of zeoiite, namPly, the intermediate pore size variety as represented, for examp:Le, ~y ZSM-5, which poesess a Constraint Index of greater than ab~lt 2 and the large pore variety as represented, for example, by zeolites Y, Beta and Z5M-12, which pcesess a Constraint indeK no greater than a~out 2.
10 Preferred cataLysts include Zeolite Beta, Zeolite Y, ZSM-5, :
ZSM-12 and ZSM-35. Both varieties of zeolites will possess a frame~ork silica-to-alum ma ratio of greater than about 7.
For purposes of this invention, the term "zeolite" is meant to include the cl~q of porokectosilicates, i.e., porous crystalline silicate~q, which contain silicon and oxygen atoms as the major components. Other components can be present in minor amcunts, usually less than 14 mole %, and preferably less than 4 mole %. ~hese ccmponents include alum mum, gallium, iron, boron, and the lihe, with alum mum being preferred. The minor Cl=Frnents can be pr~sent separately or in mixtures in the catalyst. m ey can also be present intrinsically in the framework structure of the catalyst. m e framewDrk silica-to-alumina mole ratio referrel to can be determuned by conventional analysis. This ratio is meant to represent, as closely as possible, the mole ratio of silica to alum ma in the rigid anionic framew~rk of the zeolite crystal an~d to exclude any alumina which may be present in a binder material optionally associated with the zeolite or present in cationic or other form within the channels of the zeolite. In addition, zeolites as otherwise characterized herein but which are substantially free of aluminum, i.e., having silica-to-alumina mole ratios up to and including infinity, are useful and can even be preferable in some cases.
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A convenient me~lr~ o ~h~ e~ t to ~h_ch a 7~1it rltr~lle~ ~ce~ ib~ of vdr~ G~S ~ iis `~
internal structure is the a~orementioned Constra mt Index of the zeolite. A zeolite which provides relatively restricted access to, and egress from, its intennal structure is characterized by a relatively hiqh value for the Constrai~t Index, i.e., above about 2. On the other hand, zeolites ~hich provide relatively free access to the internal zeolitic struct~e have a relatively lcw value for the Constraint }ndex, i.e., about 2 or less. me method by which Constraint Index is determuned is dP~rribed fully in U.S. Patent No. 4,016,~18, to which referenoe is made for details of the method.
Constraint Index (CI) values for scme zeolites which can be used in the process of this invention are described in the following table together with the temçerature at which the test was made:

Zeolite Constraint Index _ _ _ _ (At Test Temperature,oC) ZSM-4 0.5 (316) ZSM-5 6-8.3 (371-316) ZS~-ll 5-8.7 (371-316) Z5M-12 2.3 (316) ZSM-20 0.5 (371) ZSM-35 4-5 (454) ZSM~48 3.5 (538) ZSM-50 2.1 (427) TM~ Offretite 3.7 (316) TEA Mordenite 0.4 (316) Clinoptilolite 3.4 ~510) Mordenite 0.5 (316) REY 0.4 (316) Amorphous Silica-Alum ma 0.6 (538) Dealuminized Y 0.5 (510) Zeolite Beta 0.6-2.0 (316-399) The above-described Constraint Index is an Lmportant and even critical definition of those zeolites which are useful m the instant invention. The very nature of this parameter and the ;

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recited ~ ique by which it is determined, however, admit of . ~he p~Ss~ t~ ~h~l ~ gi~ r~ -~D~ can be tE3'.a~ ~ ~er ~cm~at different conditions and thereby exhlbi~ different constraint Indi~cc. Constraint Index seems to v~ry somewhat with severity of operation (conversion) and the presenoe or absence of binders.
Likewise, other variables, such as crystal size of the zeolite, the presence of oocluded contam m ants, etc., can affect the constraint Index. m erefore, it will ~e appreciated that it may be possible to so select test conditions, e.g., temperatures, as to establish more than one value for the Constraint Index of a particular zeolite. This explains the range of Constraint Indices for zeolite Beta.
Useful zeolite catalysts of the intermediate pore size variety, and possessLng a Constraint Index of grea~r than about 2 up to abcut 12, include such materials as ZSM-5, ZSM-ll, ZSM-23, ZSM-35, and ZSM-38.
Z3M-5 is more particularly described in U.S. Reissue Patent No. 28,341 (of original Patent No. 3,702,886). ZSM-ll is more particularly described in U.S. Patent No. 3,709,979. ZSM-23 is more p rti~larly described in U.S. Patent No. 4,076,842.
ZSM~35 is more particularly described in U.S. Patent No.
4,016,245. ZSM-38 is more particularly described in U.S. Patent No. 4,046,859. Although æ5M-38 pcescsscs a Constraint Index of 2.0, it is often classified with the intermediate pore size zeolites and will therefore be re~arded as such for purposes of this invention. -m e larye pore zeoli~ which are useful as catalysts in the process of this invention, i.e., those zeolites having a Constraint Index of no greater than about 2, are well known to 30 the art. Representative of these zeolites are zeolite Beta, ~ -zeolite X, zeolite L, zeolite Y, ultrastable zeolite Y (USY), ;
dealuminized Y (Deal Y), rare earth-exchanged zeolite Y (REY), rare earth-exchanged dealuminized Y (RE Deal Y), mordenite, -~? ~ 3 r~ 2 4 ZSM-3, ZSM-4, ZSM-12, ZSM-20, and Z5M-50 and mixtures of any of ~h~. f~ro~ -~h~ 2~C~ ~? ~?~ ~d~' of ~ -abcut 2 or less, it should be noted that this zeolite does nct behave exactly like other large pore zeolites. However, zeolite S Beta does satisfy the rrqolre~nts for a catalyst of the present invention.
Zeolite ~eta is described in U"S. Reissue Patent No.
28,341 (of original U.S. Patent No. 3,:308,069), to which reference is made for details of this catalyst.
Zeolite X is described in U.S. Patent No. 2,882,244, to which reference is made for the details of this catalyst.
Zeolite L is described in U.S. Patent No. 3,216,789, to which reference is made for the details of this catalyst.
Zeolite Y is described Ln U.S. Patent No. 3,130,007, to which reference is made for details of this catalyst.
Low sodium ultrastable zeolite Y (USY) is described in U.S. Patent Nos. 3,293,192; 3,354,077; 3,375,065; 3,402,996,;

3,449,070; and 3,595,611, to which reference is made for details of this catalyst.
Dealuminized zeolite Y (Deal Y) can be prepared by the methcd found in U.S. Patent No. 3,442,795, to which reference is made for details of this catalyst.
Zeolite ZSM-3 is described in U.S.Patent No.3,415,736, to which reference is made for details of this catalyst.
Zeolite ZSM-4 is described in U.S.Patent No.3,923,639, to ~ ~
which reference is made for details of this catalyst. - -Zeolite ZSM-12 is described in U.S.Patent No.3,832,449, to which reference is made for the details of this catalyst.
Zeolite ZSM-20 is described in U.S.Patent No.3,972,983, to which refer~noe is nade for the details of this catalyst.
Zeolite ZSM-50 is described in U.S. Patent No. 4,640,829, to which reference is made for details of this catalyst.

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Al~; ;nçllyd~l W~ m ~119 defi2~tic~ ^f~ ~ use4~ul. ..
ze~lites a~ c~ t~ b ~or~us ~ilicoalumu~n~s~pnates SU~
those disclosed in U.S. Patent No. 4,440,871, the catalytic behavior of which is similar to that of ~he aluminosilicate zeolites.
The zeolite(s) selecked for use herein will genRrally possess an alpha value of at least about 1, preferably at least 10 and more preferably at least about 100. "Alpha value", or "alpha ~umber", is a measure of zeolite acidic functionality and is mnre fully descrlhc~ to~ether with details of its mE~surement in U.S. Patent No. 4,016,218, J. Catalysis, ~, pp. 278-287 (1966) and J. Catalysis, 61, pp. 390-396 (1980). Zeolites of low acidity (alpha values of less than about 200) can _e achieved by a variety of techniques including (a) synthesizing a zeolite with a high silica/alumina ration, (b) steamlng, (c) steaming followed by dealuminization and (d) substituting fram~work alum m um with other species. For example, in th~ case of st q ~ the zeolite(s) can _e exposed to steam at elevated temperatures rangillg fm m 260C (500F) to 649C (1200F) anld preferably fram 399C (750) to 538C (1000F). This treatment can be acoomplisbed in an atmospber~ of 100% steam or an atmoephcre `~ `
oonsisting of steam and a gas which is substantially inert to the ;~
zeoli~e. A similar treatment can be aoocmplished at lower temperatures employing elevated pressure, e.g., at frcm 177C to ~ ~m `
371C (350 to 700F) with from 1010 to 20200 kPa (10 to 200 atmospheres). Specific details of several steaming procecures may be obtained fram U.S. Patent Nos. 4,325,994; 4,374,296; and -~

4,418,235. Aside frcm, or in addition to any of the foregoing prrc~dures, the surface acidity of the zeolite(s) can be eliminated or redu~o~ by treatment with bulky reagents as descri~ed in U.S. Patent No. 4,520,221.
In practicing the olefin hydration and etherification process of the presP~nt invention, it may be advantageous to :

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incDrpQ~tP the 7~nl _tetc~ ~ to g~o ot~r m2terial, i.~., a X cr b-~ r, W~l iS resista~t '~, the tt~r~x~rdt~re &~d ot conditions emplcyed in the prooess. Us,eful matrix materials include both synthetic and naturally-oc~rring sub6tances, e.g., inGrganic materials such as clày, silica andyor metal oxides.
Such materials can be either natNrally-~ccurring or can be obtained as gelatincus precipitates or gels including mixtures of silica and metal oxides. Naturally-occurring clays which can be composited with the zeolite include those of the montmorillonite and kaolin families, whic~ families include the sub-bentonites and the Xaolins oommonly k~own as Dixie, ~Nb~er-Cborgia and Florida clays or o~hers in which the main mireral oonstituent is halcysite, kaolinite, dic~ite, nacrite or anauxite. Such clays can be used in the raw state as originally mun_d or initially subjectsd to calcination, acid treatment or chemical modification.
In addition to the foregoing materials, the zeolite(s) employed herein can be oomposited with a porous matrix material such as carbon, alumina, titania, zircania, silica, 20 silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, `~
silica beryllia, silica-titania, etc., as well as ternary oxide oompositic~, such as silica-alum ma-thoria, silica-alumina-zirconia, sillca-alumina-magnesia, silica~magnesia-zirconia, etc.
m e matrix can be in the form of a cogel. The relative proportions of zeolite component(s) and matrix m~terial, on an anhydrous basis, can vary widely with the zeolite content ranging from between 1 to 99 wt%, and more usually in the range of S to 90 wt% of th~ dry ccmposite.
In some cases, it may be advantageous to provide the zeolite hydration etherification catalyst(s) in the form of an extr~date bound with a low acidity refractory oxide binder emplcying the method descr;h~d in commonly assigned, copending U.S. patent application Serial No. 44,639, filed May 1, 1987.

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Accord;nq t:t? th i f m,,c~h~, 7Q~ ''cidit~
r ~ L5" ~ b~_r, e.g., siiica, w m cn ccr~taLns at leas~ an extrusion-facilitating amcunt of the binder in a colloidal state and which is substantially free of added alkali metal base and/or basic salt, is formed into an extrudable massi, the mass is extru~ed and the resulting extrudate is dried and calcined.
m e original cations associated with zeolite(s) utilized herein can be replaced by a wide variety of other cations according to techniques well known in the art, e.g., by ion-exchange. Typical replacing cations include hydrogen, ammanium, alkyl ammDnium and metal cations, and their mixtures.
Metal cations can also be intrcduced into the zeolite. In the case of metal cations, particular preference is given to metals of Grcups IB of the Periodic Table, including, by way of exa~ple, --iron, nickel, cobalt, ccpper, ZLnC, palladium, calcium, chrcmium, tungsten, moly~denum, rare earth metals, etc. These metals can also be present in the form of their oxides.
A typical ion-exchange technique involves contacting the particular zeolite with a salt of the de3ired replacing cation.
Although a wide varietv of salts can be employed, parti~lar preference is given to chlorides, nitrates and sulfates.
Representative ionre#ch3nge techniques are discla6ed in a number of patents inclu~ing U.S. Patent Nos. 3,140,249; 3,140,251; and 3,140,253.
Following contact with a solution of the desired replacing cation, the zeolite is then preferably washed with water and dried at a temperature ranging from 66C to 316C (150 to 600F) and thereafter calcined in air or other inert gas at temperatures ranging fmm 260a to 816C (500 to 1500F) for F~riods of time ranging frcm 1 to 48 hours or more.
Ihe preferred prccess of the instant invention is illustrated in Figure 2 where optional process operation flowsi are represented by da~h lines. Tho~e optional cperations include ~ 3 iscmeriæation 220 of the butane fead stream to the MIEE
etheri.~ioation unit ~n nr;~r. to p'O~ of ~hÇ ~.I.ef;nc feedstock by dehydrogenation of C3-C4 paraffins 210. The optional dehydrogenation and isomerization pr~xxK~cpc are convention21 prooeæs operations well known~to those skilled in the petroleum re~ining arts. Prcpylene and butene feed 205 for the oxygenate proceææ is produoed at the FOC oomplex 201 or may be produced by paraffin 203 dehydrogenation. Ihe lig~lt olefin stream is fed to a C3/C4 splitter 240 which separates pr~ylene and pr~pane fro~
the C4's. The C3 rich strelm 207 is then sent to the pr~pylene hydration unit 250 where the prcpylene is oonverted to isopropanol (IPA) and di-isopropyl ether (DIPE) 209 by reaction with water 211 in oontact with solid acidic catalyst. Unreacted prc~ylene is recycled via 213 to the hydration reactor to increase the overall conversion and yield. In addition, the DIPE
yield can be inore3scd further by IPA recycled The C4 stream 215 exiting the ~plitter 240 is sent to the butene reactor section. The mixed butenes are sent first to the MIEE unit ~30 where, with methanol fecdstreom 219, isobutylene and me*banol react to form MI~æ Conditions in the reactor are chosen so that the linRar butenes do not react with methanol.
Low temperatures favor selective conversion of isdbutylene.
Isomerization unit 220 and paraffin dbhycr~gen3tion unit 210 upstream of the MT~E unit may be used to produce isabutylene from ~ ;~
excess n-butane. This allows for mK3ea~cd production of MTBE or other alkyl tertiary butyl ethers.
The effluent 217 frcm the MIBE unit is separated to pr~vide Ml~æ which is reoovered 221 and unreacted 1- and 2-butenes passLng through the MTBE reactor. These are introduced via 223 into olefins hydration unit 260 together with water 225 and are converted to 2-butanol (2-E~OH) and di-butyl ether 227 by reaction with water in contact with solid acidic catalyst m a unit that is simular to that used for propylene hydration.

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(?~i~!~1 l V, 1-h ~ y b~ CO~v~2~--' ~ v ~ig~ .e s~,~ reactor. Ui~eac~eu kuten~s m~y be re~ycled 229 to the butene hydration unit to incræase conversion and yield. Recycle of 2-butanol will increase the butyl ether yield.

5 Alcbhol recycle for tcth propylene and butene hydration also has a beneficial effect on the catalyst life when using zeolite -catalysts.
In the prooess of the present invEntion the oxygenates produced are taken frcm the group consisting of isopropyl 10 alcQhol, 2-butanol, di-isopropyl ether, di-butyl ether, isopropyl butyl ether, methyl tertiary butyl ether, ethyl tertiary butyl ether and isoprcpyl tertiary kutyl ether.
This prooess is significant since it can convert propylene and b~tenes to high-oc*ane alcohols and ethers which ~
15 may be blended into gasoline to increase oc*ane. In~irect1y, the ~-process may al_o oonvert light paraffins to oxygenates follcwLng paraffin dehydrcgenatian to olefin. ~he process offers several advan~ages over traditional iscparaffin-olefin alkylation since it l-cP~ solid acid catalysts to oonvert light olefins to 20 high-value products. The use of separate hydration and etherification reactors or zones allows far gr~ater process -~
flexibility.
~hile the invention has been described by specific -examples and erbodiments, there is no intent to limit the ~-25 inventive concept except as set forth in the follcwing claims.

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Claims (22)

1. An intergrated process for the conversion of a hydrocarbon feedstock comprising C3-C4 olefins containing isobutylene to high octane gasoline boiling range C3-C8 acyclic aliphatic oxygenates, including lower alkyl tertiary butyl ether, comprising the steps of:
a) separating the feedstock into two effluent streams one comprising a C3 hydrocarbon stream and the other a C4 hydrocarbon stream containing isobutylene;
b) feeding the C3 effluent stream and water to an olefins hydration zone in contact with an acidic hydration catalyst under olefins hydration and etherification conditions to produce di-isopropyl ether and isopropyl alcohol;
c) feeding the C4 effluent stream and lower alkyl alcohol to an etherification zone under isobutylene etherification conditions in contact with an acidic etherification catalyst to produce and recover lower alkyl tertiary butyl ether and unreacted 1- and/or 2-butenes;
d) introducing the unreacted butenes and water into an olefins hydration zone in contact with an acidic hydration catalyst under olefins hydration and etherification conditions to produce di-butyl ether and 2-butanol.

2. The process of claim 1 wherein the feedstock is produced by feeding C3-C4 paraffinic hydrocarbons to a butane isomerization zone under isomerization conditions; and feeding the effluent therefrom rich in isobutene to a dehydrogenation zone.

3. The process of any preceding claim wherein step (c) unreacted 1 and 2-butenes and step (a) C3 olefins are fed to a common olefins hydration zone with water under olefins hydration and etherification conditions in contact with an acidic hydration catalyst to produce an oxygenates mixture comprising di-isopropyl ether, dibutyl ether, isopropyl butyl ether, isopropyl alcbhol and 2-butanol.

4. The process of any preceding claim wherein the isopropyl alcohol and 2-butanol are recycled to step (b) and/or step (d) olefins hydration and etherification zone.

5. The process of any preceding claim wherein the hydrocarbon feedstock comprises light olefins from a fluidized catalytic cracking unsaturated gas plant.

6. The process of any preceding claim wherein the hydrocarbon feedstock comprises C3-C4 olefins from a C3-C4 paraffins dehydrogenation plant.

7. The process of any preceding claim wherein the lower alcohol is selected from methanol, ethanol, n-propanol, 2-propanol, 2-butanol and 1-butanol.

8. The process of any preceding claim wherein the lower alcohol comprises methanol and the lower alkyl tertiary butyl ether comprises methyl tertiary butyl ether.

9. The process of any preceding claim wherein step (c) acidic etherification catalyst comprises sulfonated resin type catalyst.

10. The process of any preceding claim wherein step (c) etherification conditions comprise temperature between 20 and 150°C.

11. The process of claim 10 wherein step (c) etherification conditions comprise temperature between 50 and 125°C.

12. The process of any preceding claim wherein step (b) and step (d) olefins hydration catalyst comprises acidic shape selective zeolite selected from intermediate pore size or large pore size zeolites possessing a Constraint Index of 2 to 12 or zeolites possessing a Constraint Index of 2 or less.

13. The process of claim 12 wherein step (b) and step (d) hydration catalyst, alike or different, is selected from zeolites ZSM-5, Z5M-11, ZSM-23, ZSM-35, X, L, Y, USY, REY, Deal Y, Re Deal Y, Z5M-3, ZSM-4, ZSM-12, ZSM-20, ZSM-50 and zeolite beta.

14. me process of any preceding claim wherein the olefins hydration and etherification conditions comprise temperature between 60 to 450°C and a pressure of from 670 to 24130 kPa.

15. The process of claim 14 wherein the overall mole ratio of water in step (b) and/or step (d) hydration zone is between 0.1 to 30.

16. The process of claim 15 wherein the LHSV in step (b) and/or step (d) hydration zone is between 0.1 to 20.

17. An integrated process for the conversion of hydrocarbon feedstock comprising C3-C4 olefins containing isobutylene to high octane gasoline boiling range C3-C8 acyclic aliphatic oxygenates, including lower alkyl tertiary butyl ether, comprising the steps of:
a) feeding the feedstock and lower alkyl alcohol to an etherification zone under isobutylene etherification conditions in contact with acidic etherification catalyst and recovering lower alkyl tertiary butyl ether and unreacted hydrocarbons comprising propylene and butene; and b) passing the unreacted hydrocarbons and water into an olefins hydration zone in contact with acidic hydration catalyst under olefins hydration and etherification conditions to produce C3-C8 acyclic aliphatic oxygenates.

18. The process of claim 17 wherein the oxygenates are selected from isopropyl alcohol, 2-butanol, di-isopropyl ether, di-butyl ether, isopropyl butyl ether, methyl tertiary butyl ether, ethyl tertiary butyl ether, isopropyl tertiary butyl ether and 2-butyl tertiary butyl ether.

19. The process of claim 17 or 18 wherein the lower alcohol is selected from methanol, ethanol, n-propanol, 2-propanol, 1-butanol and 2-butanol.

20. The process of claim 17, 18 or 19 wherein the lower alcohol comprises methanol and the lower alkyl tertiary butyl ether comprises methyl tertiary butyl ether.

21. The process of claim 17, 18, 19 or 20 wherein the 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.

22. The process of any preceding claim wherein the oxygenates are selected from isopropyl alcohol, 2-butanol, di-isopropyl ether, di-butyl ether and methyl tertiary butyl ether, ethyl tertiary butyl ether, isopropyl tertiary butyl ether and 2-butyl tertiary butyl ether.