CA2030797A1 - Integrated process for enhancing high octane ether production and olefin conversion in gasoline - Google Patents

Abstract

INTEGRATED PROCESS FOR ENHANCING HIGH OCTANE ETHER
PRODUCTION AND OLEFIN CONVERSION IN GASOLINE

ABSTRACT

An integrated process is disclosed for converting C3+ and/or C4+ olefins to high octane ethers, alcohols and gasoline boiling range hydrocarbons. The invention incorporates C4+ tertiary olefin etherification with lower alkanol to produce lower alkyl tertiary alkyl ether in a first etherification step under mild conditions and linear olefins hydration and etherification using acidic catalyst in a second sequential step to produce additional high octane oxygenates. Unreacted olefins are passed to an olefins conversion zone in contact with zeolite catalyst for conversion to gasoline, distillate or aromatics. The invention particularly comprises an integrated process for the conversion of hydrocarbon feedstock comprising C3-C4 olefins containing isobutylene to high octane alcohol and ethers, including MTBE and TAME.

Description

) 7 ~ I

INTEGRATED PROCESS FOR ENHANCING HIGH OCTANE ETHER
PRODUCTION AND OLEFIN CONVERSION IN GASOLINE

This invention relates to an integrated process for the conversion of light olefins to ethers including methyl tertiary bu~yl ether and high octana gasoline.
More particularly, the inven~ion relates to the catalytic hydration and etherification of light olefins to produce mixed ethers followed by unreacted olefins aromatization or conversion to gasoline. The mixed ether 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 requirement to establish alternate processes for manufacturing high octane gasoline in view of the regulated requirement to eliminate lead additives as octane enhancers as well as the development of more efficient, higher compression ratio gasoline engines requiring higher octane fuel. To meet these requirements the industry has developed non-lead octane boosters and has reformulated high octane gasoline to incorporate an increased fraction of aromatics. While these and other approaches will fully meet the technical requirements of regulations requiring elimination of gasoline lead additives and allow the industry to meet the burgeoning market demand for high octane gasoline, the economic impact on the cost of gasoline is significant. Accordingly, workers in the field have intensified their effort to discover new processes to manufacture the gasoline products required by the market place. One important focus of that research is processes to produce high octane gasolines blended with lower aliphatic alkyl ethers as octane boosters and supplementary fuels. C5-C7 methyl alkyl 2 0 3 ~ rJ~ ~ ~

ethers, especially methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether (TAME) have been found particularly useful for enhancing gasoline octane, as has di-isopropylether(DIpE). Therefore, improvements to the processes related to the production of these ethers are matters of high importance and substantial challenge to research workers in the petroleum refining arts.
It is well known that isobutylene may be reacted with methanol over an acidic catalyst to provide methyl tertiary butyl ether (MT~E) and isoamylenes may be reacted with methanol over an acidic catalyst to produce tertiary amyl m~thyl ether (T~ME). The reaction is a useful preparation for these valuable gasoline octane enhancers and is typical o~ the reaction of the addition of lower alkanol to the more reac~ive tertiary alkenes of the type R2C=CH2 under mild conditions to form the corresponding tertiary alkyl ethers. The feedstock for the etherification reac~ion may be taken from a variety of refinery process streams such as the unsaturated gas plant of a fluidized bed catalytic cracking operation containing mixed light olefins, preferably rich in isobu~ylene. Light ole~ins such as propylene and isomers of butene other than isobutylene in the feedstock are essentially unreactive toward alcohols under the mild, acid ca~alyzed etherification reaction conditions employed to produce lower alkyl tertiary butyl ether. The further utilization, without recycle, of these unreacted olefins and alcohols to meet the overall product goals of the process would be a welcomed improvement.
Lower molecular weight alcohols and ethers such a isopropyl alcohol (IPA) and diisopropyl ether (DIPE) are in the gasoline boiling range and are known to have a high blending octane number. In addition, by-product propylene from which IPA and DIPE can be made is usually available in a fuels refinery. The 203~797 petrochemicals industry also produces mixtures of light olefin streams in the C2 and C7 molecular weight range and the conversion of such stream5 or fractions thereof to alcohols and/or ethers can also provide products useful as solvents and blending stocks for gasoline.
The catalytic hydration of olefins to provide alcohols and Pthers is a well-established art and is of si~nificant commercial importance. Representative olefin hydration processes are disclosed in U. S.
Patents Nos. 2,262,913; 2,477,380; 2,797,247;

3,798,097; 2,805r260; 2,830,090; 2,861,045; 2,891,999;
3,006,970, 3,198,752: 3,810,848; 3,989,762, among others.
Olefin hydration employing zeolite catalysts is known. As disclosed in U. S. Patent No. 4,214,107, lower olefins, in particular propylene, are catalytically hydrated over a crystalline aluminosilicate zeolite catalyst having a silica to alumina ratio of at least 12 and a Constraint Index of from 1 to 12, e.g., acidic ZSM-5 type zeolite, to provide the corresponding alcohol, essentially free of ether and hydrocarbon by-product.
The production of ether from secondary alcohols such as isopropanol and light olefins is known. As disclosed in U. S. Patent No. 4,182,914 DIPE is produced from IPA and propylene in a series of operations employing a strongly acidic cation exchange resin as catalyst.
The surprising discovery has been made that conversion of the light alkenes component of a hydrocarbon feedstream for high octane ether production can be substantially increased by serially integrating the initial iso-olefins etherification step with processes capable of converting unreacted light olefins to alcohols and ethers by hydration and etherification, followed by aromatization or oligomerization of remaining unreacted olefins to higher hydrocarbons such as gasoline and distillate. The process enhances the production of both the desirable tertiary alkyl ethers as well as iso-ethers.
More particularly, a process has been discovered for the conversion of C4~ olefinic hydrocarbon fPedstock containing C4-C5 ~ertiary olefins into high octane gasoline boiling range oxygenates and higher molecular weight gasoline boiling range hydrocarbons.
The process comprises the following steps:
(a) reacting a fresh mixture of excess lower alkanol and said hydrocarbon feedstock in the presence of acidic etherification catalyst under etherification conditions whereby an etherification effluent stream containing lower alkyl tertiary ~lkyl ethers, unreacted lower alkanol and linear C4+ olefinic hydrocarbons is produced;
(b) separating said effluent stream to recover C5+ gasoline containing high octane lower alkyl tertiary alkyl ethers and a stream containing said unreacted lower alkanol and C4- hydrocarkons:
(c) introducing said unreacted alkanol and C4-hydrocarbon stream and feedstream containing C3 hydrocarbons and water into an olefins hydration zone in contact with acidic hydra~ion catalyst under olefins hydration and etherification conditions whereby C3+
aliphatic oxygenates are produced;
(d) separating step (c) effluent stream and recovering said oxygenates containing high octane ethers and a stream containing unreacted linear C4-olefins and alkanol by-product;
(e) contacting said unreacted linear olefins stream with an acidic metallosilicate catalyst in a conversion zone under olefins conversion conditions at elevated temperature whereby higher molecular weight gasoline boiling range hydrocarbons are produced.
- Optionally, step (d) unreacted olefins stream containing alkanol by-product is separated and the 7 ~ 7 olefins portion is passed ~o step (e). Also, step (c) nydration zone may be a common hydration zone for C3 and C4 hydrocarbons or a two reactor system to upgrade C3 and C4 hydrocarbons separately under different conditions.
In one embodiment of the invention the C3 hydrocarbon feedstream to the hydration and etherificaton step is omitted and only unreacted olefins from the iso-olefin etherificaton step are reacted in the hydration and etherification zone.
The Figure is a flow schema~ic of the process of the present invention.
In the preferred embodiment of the instant invention the principal components of known processes are integrated in a manner providing a highly advantageous and surprising advancement in refinery technology leading to the production of high octane gasoline blending components as well gasoline distillate and/or aromatics. Known processes are combined in a unique configuration that provides enhancement of the performance of component processes, achieving surprising advantages for the integrated process. The processes integrated include the etherification of tertiary olefins to produce lower alkyl tertiary alkyl ethers such as MTBE (methyl tertiary butyl ether) and TA~E (methyl tertiary amyl ether), olefins hydration to produce alcohols and ethers and olefins conversion over zeolite catalyst to produce gasoline (MOG-Mobil Olefins to Gasoline process), distillate (MOGD-Mobil-Olefin to Gasoline and Distillate process) or aromatics (M-2 Forming-Mobil Aromatization process). Olefin feedstock may be produced, in entirety or in part, by including a paraffins dehydrogenation step in the process.
Lower alkyl in the present invention refers to Cl-C4alkyl derived from etherification using methanol, ethanol, l-propanol, isopropanol, 2-butanol and 2~3~7~

l-butanol. Tertiary alkyl refers to C4~C5 tertiary alkyl groups derived from the etherification of tertiary olefins such as isobutene and isoamylene. The term oxygenates or oxygenate as used herein comprises, individually or in combination, Cl-C8 low r aliphatic, acyclic alcohols or alkanol and symmetrical or unsymmetrical C2-Cg ethers.
The process of the present invention is directed to maximizing the utilization of C3-C4 refinery streams for the production of those gasoline range oxygenated species, or oxygenates, known to exhi~it high octane numbers which are useful for gasoline product blending.
Table 1 lists some of those oxygenated species of particular interest as products of the present invention.

Table 1 Product Blending octanes Research Motor Methyl Tertiary Butyl Ether (MTBE) 120 100 Di-isopropyl ether (DIPE) 109 99 Isopropyl alcohol (IPA) 116 95 Butanol (2-BuOH) 110 97 Ethyl Tertiary Butyl Ether (ETBE) 118 105 Isopropyl Tertiary Butyl Ether (IPTBE) 116 Other ethers which can be produced as products of the present invention include methyl isopropyl ether methyl isobutyl ether and di-isobukyl ether.
In the process of the instant invention it has been discovered that the known greater reactivity of tertiary olefins of the structure R2C=CH2 or R2C=CHR
compared to linear olefins of the structure RC~=CHR in etherification reaction with lower alcohols can be advantageously utilized to selectively etherify 2 0 3 ~ 7 ~ 7 ~-5324 -7-isobutylene and tertiary pentene in the presence of linear olefins to produce high octane lower alkyl tertiary butyl ether and tertiary amyl ether. Then, in a sequential process configuration, unreacted linear olefins are converted to high octane gasoline range oxygenates by hydration and etherification. The unreacted linear olefins feed to the hydration and etherification step may be augmented with olefin containing feedstock such as C3 hydrocarbons containing propene. Propene can also be processed in a separate reactor.
Isobutylene etherification conditions are known in the art and, in the instant invention, comprise mild conditions of low tempera~ure and high liquid hourly space velocity (LHSV). Isobutylene etherification temperature can range from 20C to 150C and preferably between 60 and 125C.
In the preferred embodiments of this invention, methanol is reacted with C3-C4 olefinic hydrocarbon feedstock such as FCC unsaturated gas containing olefins, particulaxly iso-olefins, to produce methyl tertiary butyl ether. In the reaction, methanol is generally present in a stoichiometric excess amount between l and lO0 percent, based upon isobutylene.
Unreacted alkanol such as methanol largely will end up in the MTBE product as a result of azeotrope formation during fractionation. Typically, this would present problems of an aqueous phase formation in gasoline.
However, isopropyl alcohol (IPA~ and sec-butyl alcohol (SEC) formed in subsequent olefin hydration steps of the overall process mitigates against two phase formation by solubilizing methanol in the gasoline pool.
Methanol may be readily obtained from coal by gasification to synthesis gas and conversion of the synthesis gas to methanol by well-established industrial processes. As an alternative, the methanol 203~7~i may be obtained from natural gas by other conventional processes, such as steam reforming or partial oxidation to make the intermediate syngas. Crude mathanol from such processes usually contains a significant amount of water, usually in the range of 4 to ~0 wt%. The etherification catalys~ employed is preferably an ion exchange resin in the hydrogen form: however, any suitable acidic catalyst may be employed. Varying degrees of success are obtained with acidic solid catalysts; such as, sulfonic acid resins, phosphoric acid modified kieselguhr, silica alumina and acid zeolites such as zeolite beta and ZSM-5. Typical hydrocarbon ~eedstoc~ materials for etherification reactions include 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.
The 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, June 16, 1975, and S. Pecci and T. Floris, Hvdrocarbon Processina, December 1977. An article entitled "MTBE
and TAME - A Good Octane Boosting Combo," by J.D.
Chase, et al., The Oil and Gas Journal, April 9, 1979, pages 149-152, discusses the technology. A preferred catalyst is a bifunctional ion exchange resin which etherifies and isomerizes the reactant streams. A
typical acid catalyst is Amberlyst 15 sulfonic acid resin, a product of Rohm and Haas Corporation.
MTBE is known to be a high octane ether. The article by J.D. Chase, et al., Oil and Gas Journal, April 9, 1979, discusses the advantages one can achieve by using these materials to enhance gasoline octane.
The octane blending number of MTBE when 10% is added to a base fuel (R~O = 91) is 120. For a fuel with a low motor rating (M+O = 83) oc~ane, the blending value of 2~3~97 MTBE at the 10% level is 103. On the other hand, for an (R+O) of 9S octane fuel, the blending value of 10 ~TBE is 114.
Processes for producing and recovering MTBE and other methyl tertiary alkyl ethers from iso-olefins are known to those skilled in the art, such as disclosed in U.S. Patents 4,544,776 (Osterburg, et al.) and 4,603,225 (Colaianne et al.). In tha prior art various suitable extraction and distillation techniques are known for recovering ether and hydrocarbon streams from etherification effluent.
The opera~ing conditions of the olefin hydration process herein are not especially critical and include a temperature of from 60 to 450C, preferably from 90 to 220C and most preferably from 120 to 200C, a pressure of from 120 to 200C, a pressure of from 690 to 16.6X103kPa ~100 to 3500 psi), preferably from 3.45X103 to 13.8X103kPa (500 to 2000 psi), a water to olefin mole ratio of from 0.1 to 30, preferably from 0.2 to 15 and most preferably from 0.3 to 3.
The olefin hydration process of this invention can be carried out under dense phase, liquid phase, vapor phase or mixed vapor-liquid phase conditions in batch or continuous manner using a stirred tank reactor or fixed bed flow reactor, e~g., trickle-bed, liquid-up-flow, liquid-down-flow, counter-current, co-current, etc. Reaction times of from 20 minutes to 20 hours when operating in batch and an LHSV o~ from 0.1 to 20, preferably 0.1-2, when operating continuously are suitable. A portion of unreacted olefin may be recovered and recycled to the reactor.
The catalyst employed in the olefin hydration and etherification operations which are connected sequentially downstream of isobutylene etherification operations is shape-selective acidic zeolite. In general, the useful catalysts embrace two categories of æeolite, namely, the intermediate pore size variety as 2 0'~

F-5324 -lO-represented, for example, by ZSM-5, which possess a Constraint Index of greater than 2 and the large pore variety as represented, for example, by zeolites Y, Beta and ZSM-12, which possess a Constraint index no greater than 2. Preferred catalysts include Zeolite Beta, Zeolite Y, ZSM-12, ZS~-S and ZSM-35. Both varieties of zeolites will possess a framework silica-to-alumina ratio of greater ~han 7. In addition, acid resin catalysts are useful.
For purposes of this invention, the term "zeolite"
is meant to include the class of porotectosilicates, i.e., porous crystalline silicates, which contain silicon and oxygen atoms as the major components.
Other components can be present ~n minor amounts, usually less than 14 mole %, and preferably less than 4 mole %. These components include aluminum, gallium, iron, boron, and the like, with aluminum being preferred. The minor ccmponents can be present separately or in mixtures in the catalyst. They can also be present intr nsically in the framework structure of the catalyst. The frameworX
silica-to-alumina mole ratio referred to can be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the mole ratio of silica to alumina in the rigid anionic framework of the zeolite crystal and to exclude any alumina which may be present in a ~inder 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.
A convenient measure of the extent to which a zeolite provides controlled access to molecules of varying sizes to its internal structure is the 2~3~797 F-532~

aforementioned Constraint Index of the zeolite. A
2eolite which provides relatively restricted access to, and egress from, its internal structure is ~haracterized by a relatively high value for the ; Constraint Index, i.e., above 2. On the other hand, zeolites which provide relatively free access to the internal zeolitic structure have a relatively low value for the Constraint Index, i.e., 2 or less. The method by which Constraint Index is determined is described fully in U.S. Patent No. 4,016,218.
Useful zeolite catalysts of the intermediate pore size variety, and possessing a Constraint Index of greater than 2 up to 12, include such materials as ZSM-5, ZSM-ll, ZSM-23, ZSM-35, and ZSM-38.
ZSM-5 is more particularly described in U.S.
Reissue Patent No. 28,341 (of original Patent No.
3,702,8~6); ZSM-ll is more particularly described in U.S. Patent No. 3,709,979: ZSM-23 is more particularly described in u.S. Patent No. 4,076,842; ZSM-35 is more particularly described in U.S. Patent N~. 4,016,245;
and ZSM-38 is more particularly described in U.S.
Patent No. 4,046,859. Although ZS~-38 possesses a Constraint Index of 2.0, it is often classified with the intermediate pore size zeolites and will therefore ?5 be regarded as such for purposes of this invention.
The large pore zeolites which are useful as catalysts in the process of this invention, i.e., those zeolites having a Constraint Index of no greater than 2, are well known to the ar~. 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 (REY3, rare earth-exchanged dealuminized Y (RE Deal Y), mordenite, ZSM-3, ZSM-4, ZSM-12, ZSM-20, and ZSM-50 and mixtures of any of the foregoing. Although zeolite Beta has a Constraint Index of 2 or less, it should be noted that this zeolite does not behave exactly like other large 203~79r'1 F-5~24 -12~

pore zeolites. However, zeolite Beta does satisfy the requirements for a catalyst of the presenk invention.
Zeolite Beta is described in U.S. Reissue Patent No. 28,341 (of original U.S. Patent No. 3,308,069);
Zeolite X is described in U.S. Patent No. 2,882,244;
Zeolite L is described in U.S. Patent No. 3,216,789;
Zeolite Y is described in U.S. Patent No. 3,130,007.
Low sodium ultrastable zeolite Y (USY) is described in U.S. Patent NosO ~,293,192; 3,354,077:
3,375,065; 3,402,996,; 3,449,070; and 3,595,611.
Dealuminized zeolite Y (Deal Y) can be prepared by the method found in U.S. Patent No. 3,442,795.
Zeolite ZS~-3 is described in U.S.Patent No.
3,415,736; Zeolite ZSM-4 is described in U.S. Patent No. 3,923,639; Zeolite ZSM-12 is described in U.S.Patent No.3,832,~49, Zeolite ZSM-20 is described in U.S.Patent No.3,972,983; and Zeolite ZSM-50 is described in U.S. Patent No. 4,640,829.
Also, included within the definition of the useful zeolites are crystalline porous silicoaluminophosphates such as those disclosed in U.S. Patent No. 4,440,871, the catalytic behavior of which is similar to that of the aluminosilicate zeolites.
The zeolite(s) selected for use herein will 2S generally possess an alpha value of at least 1 and preferably at least 10. For the olefins hydration reaction, the most preferred alpha value for fresh catalyst is at least 400. "Alpha value", or "alpha number", is a measure of zeolite acidic functionality and is more fully described together with details o~
its measurement in U.S. Patent No. 4,016,218, J.
Catalysis, 6, pp. 278-287 (1966) and J. Catalysis, 61, pp. 390-396 (1980~. Zeolites of low acidity (alpha values of less than about 200) can be achieved by a variety of techniques including (a) synthesizing a zeolite with a high silica/alumina ration, ~b) steaming, (c) steaming followed by dealuminization and 21~ J ~ r~

(d) substituting framework aluminum with other species.
For example, in the case of steaming, the zeolite(s) can be exposed to steam at elevated temperatures - ranging from 260 to 6500c and preferably from 400 to540C. This treatment can ~e accomplished in an atmosphere of 10~% steam or an atmosphere consisting of steam and a gas which is substantially inert to the zeolite. A similar treatment c~n be accomplished at lower temperatures employing elevated pressure, e.g., at from about 177 to 370C wi~h from 10 to 200 atmospheres (1013.0 to 20260 ~Pa). Specific details of several steaming procedures may be gained from the disclosures of U.S. Patent Nos. 4,325,994; 4,374,296;
and 4,418,235. Aside from, or in addition to any of the foregoing procedures, the surface acidity of the zeolite(s) can be eliminated or raduced by treatment with bulky reagents as described in U.S. Patent No.
4,520,221.
In practicing the ole~in hydration and ~0 etherification proces~ of the present invention, it can be advantageous to incorporate the z801ite(s) into some other material, i.e., a matrix or binder, which is resistant to the temperature and other conditions employed in the process. Useful matrix materials include both synthetic and naturally-occurring substances, e.g., inorganic materials such as clay, silica and/or mPtal oxides. Such materials can be either naturally-occurring or can be obtained as gelatinous 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, which families include the sub-ben~onites and the kaolins commonly known as Dixie, McNamee-Georgia and Florida clays or others in which the main mineral constituent is haloysite, kaolinite, dickite, nacrite or anauxi~e.
Such clays can be used in the raw state as originally ~03~7~

mined or initially subjected to calcination, acid treatment or chemical modification.
In the instant invention, ~fter iso-olefin etherification and linear olefin hydration steps, unreacted butenes and lower olefins along with or without alcohol by-product from the hydration zone are converted to gasoline, distillate or aromatics by the MOG, MOGD or M-~ Forming process in contact with metallosilicate zeolite-type catalyst such as ZSM-5. In the case of conversion to aromatics of the hydration zone effluent, paraffins in the effluent can also be converted to aromatics by the M-2 Forming process.
Recent developments in zeolite catalyst and hydrocarbon conversion processes have created interest in using oxygenates and olefinic feedstocks for producing C5~
gasoline, diesel fuel, etc. In addition to the basic work derived from ZSM-5 type zeolite catalyst, a number of discoveries have contributed to the development of a new industrial process. This process has significance as a safe, environmentally accepta~le technique for utilizing feedstocks that contain lower olefins, especially C2-C5 alkenes. In U.S. Patents 3,960,978 and 4,021,502, Plank, Rosinski and Givens disclose conversion of C2-C5 olefins, alone or in admixture with paraffinic components into higher hydrocarbons over crystalline zeolites having controlled acidity.
Garwood et al~ have also contributed improved processing techniques in U.S. Patents 4,150,062, 4,211,640 and 4,227,992. The conversion of paraffins and/or olefins to aromatics is described in U.S.
patents 3,760,024 and 3,756,942 to Cattanach, UOS.
patent 3,845,150 to Yan et al., U.S. patent 4,090,949 to Owen et al.
Operating details for the typical conversion of olefins to gasoline or distillats as incorporated in the preferred unique embodiments of the present 2~)30r~7 invention are disclosed in U.S. Patents 4,456,779;
4,497,968 to Owen et al. and 4,433,185 to Tabak.
Referring now to the Figure a pre~erred embodiment of the instant invention is illustrated. In the process C4* hydrocarbons feedstoc~ are passed 310 to etherification zone 320 containing an acidic catalyst under tertiary olefin etherification conditions as previously described herein in con~unction with methanol feedstream 315. Typically, methanol may be in excess of the stoichiometric amount to etherify tertiary olefins in the hydrocarbon ~eedstock to assure essentially complete conversion to the corresponding lower alkyl tertiary alkyl ether. The excess can be between 1-100%, but preferably 30%. The etherification effluent stream is separa~ed by distillation to yield C5+ ether rich gasoline 330 containing MTBE and a portion of unreacted methanol. The remaining unreacted methanol and linear C4~ olefins are passed 340 to the hydration and etheri~ication zone 350 in contact with catalyst and under such condition as described previously herein. Water and C3 hydrocarbon feedstock 360 containing propylene are also introduced to the hydration zone 350 wherein olefins are hydrated to alcohols and alcohols etherified. While the preferred embodiment of the invention includes C3 feedstream to the hydration æone, this i8 no~ required and a useful embodiment omits C3 feed, limiting hydration and etherification to linear olefins in the iso-olefin etherification effluent. C3 hydration can be carried out in a separate reaction vessel as part of hydration zone 350. The products are separated 365 as primarily acyclic lower aliphatic oxygenates including mixed ethers. The oxygenates comprise isopropyl alcohol, 2 butanol, di-isopropyl ether, di-butyl ether, methyl sec-butyl ether, methyl isopropyl ether. An unreacted C4- hydrocarbon stream 370 is passed to conversion zone 380 under olefins to gasoline 203~7~

conversion conditions at elevated temperature in contact with zeolite catalyst such as ZSM-5. C5+
gasoline 385 is produced. Other effluents from the conversion zone may include LPG 390 and C2- hydrocarbon 395. Optionally, The C4-hydrocarbon stream 370 may be converted to gasoline and distillate, or aromatics, in contact with zeolite catalyst under conditions well known in the art and described in ~he referenced patents herein before.
In an optional variation of the present invention, all or a portion of effluent stream 340 may be passed to unit 380 through conduit 305.
In the present inven~ion, it is possible to use acidic zeolite such as ZSM-5 in each of the individual lS process steps: iso-olefin etherification, linear olefin hydration and etherification, and olefin conversion to higher molecular weight product. Accordingly, when the same catalyst is used a common catalyst regeneration system may be used. This feature of the invention provides a significant occasion for cost savings.

. . ,

Claims (19)

1. A process for the conversion of C4+ olefinic hydrocarbon feedstock containing C4-C5 tertiary olefins into high octane gasoline boiling range oxygenates and higher molecular weight gasoline boiling range hydrocarbons comprising:
(a) reacting a fresh mixture of excess lower alkanol and said hydrocarbon feedstock in the presence of acidic etherification catalyst under iso-olefins etherification conditions whereby an etherification effluent stream containing lower alkyl tertiary alkyl ethers, unreacted lower alkanol and C4+ hydrocarbons containing linear olefins is produced;
(b) separating said effluent stream to recover C5+ gasoline containing high octane lower alkyl tertiary alkyl ethers and a stream containing a portion of said unreacted lower alkanol and C4- hydrocarbons;
(c) introducing step (b) unreacted alkanol and C4- hydrocarbon stream and feedstream containing C3 hydrocarbons and water into an olefins hydration zone in contact with acidic hydration catalyst under linear olefins hydration and etherification conditions whereby C3+ aliphatic oxygenates are produced;
(d) separating step (c) effluent stream and recovering said oxygenates containing high octane ethers and a stream containing unreacted linear C4-olefins and alkanol by-product;
(e) contacting step (d) unreacted linear olefins and alkanol stream with an acidic metallosilicate catalyst in a conversion zone under olefins conversion conditions at elevated temperature whereby higher molecular weight gasoline boiling range hydrocarbons are produced.

2. The process of claim 1 wherein said lower alkanol is taken from the group of methanol, ethanol, 1-propanol, isopropanol and 1-butanol.

3. The process of claim 2 wherein said lower alkanol comprises preferably methanol.

4. The process of claim 1 wherein said lower alkyl tertiary alkyl ethers comprise MTBE and TAME.

5. The process of claim 1 wherein said C4-hydrocarbons comprise linear olefins.

6. The process of claim 1 wherein said C3+
oxygenates comprise isopropyl alcohol, 2-butanol, di-isopropyl ether, di-butyl ether, methyl sec-butyl ether, methyl isopropyl ether.

7. The process of claim 1 wherein said metallosilicate catalyst comprises a shape-selective, medium pore, acid aluminosilicate zeolite-type catalyst.

8. The process of claim 7 wherein said zeolite comprises ZSM-5.

9. The process of claim 1 wherein said olefin conversion conditions comprise olefin to gasoline conversion conditions and said higher molecular weight hydrocarbons comprise gasoline boiling range hydrocarbons.

10. The process of claim 1 wherein said olefin conversion conditions comprise olefin to gasoline and distillate conversion conditions and said higher molecular weight hydrocarbons comprise gasoline and distillate boiling range hydrocarbons.

11. The process of claim 1 wherein said olefin conversion conditions comprise olefin and paraffin conversion conditions and said higher molecular weight hydrocarbons comprise aromatics.

12. A process for the conversion of C4+ olefinic hydrocarbon feedstock rich in C4-C5 tertiary olefins into high octane gasoline boiling range oxygenates and higher molecular weight gasoline boiling range hydrocarbons comprising:
(a) reacting a fresh mixture of excess lower alkanol and said hydrocarbon feedstock in the presence of acidic etherification catalyst under iso-olefins etherification conditions whereby an etherification effluent stream containing lower alkyl tertiary alkyl ethers, unreacted lower alkanol and C4+ hydrocarbons containing linear olefins is produced;
(b) separating said effluent stream to recover C5+ gasoline containing high octane lower alkyl tertiary alkyl ethers and a stream containing a portion of said unreacted lower alkanol and C4- hydrocarbons;
(c) introducing step (b) unreacted alkanol and C4- hydrocarbon stream and water into an olefins hydration zone in contact with acidic hydration catalyst under linear olefins hydration and etherification conditions whereby C4+ aliphatic oxygenates are produced:
(d) separating step (c) effluent stream and recovering said oxygenates containing high octane ethers and a stream containing unreacted linear C4- , olefins;
(e) contacting step (d) unreacted linear olefins stream with an acidic metallosilicate catalyst in a conversion zone under olefins conversion conditions at elevated temperature whereby higher molecular weight gasoline boiling range hydrocarbons are produced.

13. The process of claim 12 wherein said lower alkanol is taken from the group consisting essentially of methanol, ethanol, 1-propanol, isopropanol and 1-butanol.

14. The process of claim 12 wherein said olefin conversion conditions comprise olefin to gasoline conversion conditions and said higher molecular weight hydrocarbons comprise gasoline boiling range hydrocarbons.

15. The process of claim 12 wherein said olefin conversion conditions comprise olefin to gasoline and distillate conversion conditions and said higher molecular weight hydrocarbons comprise gasoline and distillate boiling range hydrocarbons.

16. The process of claim 12 wherein said olefin conversion conditions comprise olefin and paraffin conversion conditions and said higher molecular weight hydrocarbons comprise aromatics.

17. The process of claim 1 or 12 wherein said acidic hydration and etherification catalyst is taken from the group consisting essentially of ZSM-5, zeolite Beta and acidic resins.

18. The process of claim 1 wherein step (c) olefins hydration zone comprises separate C3 olefin hydration and C4+ olefin hydration zones under different hydration conditions.

19. An integrated reactor system for the conversion of olefins to high octane oxygenates and higher molecular weight gasoline boiling range hydrocarbons, comprising in combination:

first reactor means for containing catalyst for the etherificaton of iso-olefins;
second reactor means for linear olefins etherification receivably connected to receive a portion of the effluent of said first reactor means;
third reactor means for olefins conversion receivably connected to receive a portion of the effluent of said first reactor means.