WO1990011268A1

WO1990011268A1 - Process for the production of tertiary alkyl ethers and tertiary alkyl alcohols

Info

Publication number: WO1990011268A1
Application number: PCT/US1990/001494
Authority: WO
Inventors: Harold Set Chung; Andrew Jackson; Margaret May-Som Wu
Original assignee: Mobil Oil Corporation
Priority date: 1989-03-20
Filing date: 1990-03-20
Publication date: 1990-10-04
Also published as: AU624495B2; EP0419628A1; CA2028135A1; AU5350790A; JPH03504730A

Abstract

A process for producing lower alkyl tertiary alkyl ethers or tertiary alkyl alcohol, such as methyl tertiary butyl ether (MTBE), methyl tertiary amyl ether (TAME) or tertiary butyl alcohol, wherein the 1-alkene component of the hydrocarbon feedstream to an etherification or olefin hydration process is separated by selective oligomerization in contact with a reduced chromium on silica support catalyst producing useful hydrocarbons of higher molecular weight, such as gasoline, distillate and lube range hydrocarbons. It has further been found that separation of the 1-alkene component of the hydrocarbon feedstream can be accomplished in an oligomerization process integrated either upstream or downstream of the etherification step.

Description

PROCASS FOR THE PRODUCTION OF TERTIARY ALKYL

ETHERS AND TERTIARY ALKYL ALCOHOLS

This invention relates to a new integrated process for the production of lower alkyl tertiary alkyl ether or alkanol. More particularly, the invention relates to a novel combined process for the selective oligomerization of 1-alkenes and etherification or hydratiαn of iso-olefins in a C₄+ hydrocarbon feedstock for the production of methyl tertiary butyl ether (MTBE) and methyl tertiary amyl ether (TAME).

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 developnent 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

arαmatics. While these and other approaches will fully meet the technical requirements of regulations requiring elfάnination 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 a new process to produce high octane gasolines blended with lower aliphatic alkyl ethers as octane boosters and sijpplementary fuels. C₅-C₇ methyl alkyl ethers, especially tertiary alkyl ethers such as methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether (TAME) , or the corresponding tertiary alcohol, have been found particularly useful for enhancing gasoline octane. 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 known that isobutylene may be reacted with methanol over an acidic catalyst to provide methyl tertiary butyl ether (MTBE) and isoamylenes may be reacted with methanol over an acidic catalyst to produce tertiary-amyl methyl ether (TAME). Similarly, these iso-olefins can be hydrated in the presence of an acid catalyst to give alcohols. In these processes, a problem of major iπportance is the separation of the reaction products and separation of unreaσted hydrocarbons. For instance, the feedstream to an etherification process can be the C₄ and/or C₅ fraction from a fluid catalytic cracking unit containing a full spectrum of isomeric alkanes and alkenes of which only the iso-olefins react with methyl or ethyl alcchol to form the preferred lower alkyl tertiary butyl or tertiary amyl ether. How unreacted materials are separated and the utility to which they are directed greatly affects process economics.

The catalytic hydration of olefins to provide alcohols and ethers is a well-established art and is of significant commercial importance. Representative olefin hydration processes are disclosed, among others, in U. S. Patents Nbs. 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; and 3,989,762.

Olefin hydration etrploying 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 coi-respαnding alcohol, essentially free of ether and hydrocarbon by-product.

Recently, novel lubricant oompositions (referred to herein as HVT-PAO) cctprising polyalpha-olefins and methods for their preparation employing, as catalyst, reduced chromium on a silica support have been disclosed in U.S. Patent Nos. 4,827,064 and 4,827,073. The process comprises contacting C₆-C₂₀ 1-alkene feedstock with reduced valence state chromium oxide catalyst on porous silica support under oligomerizing conditions in an oligcmerization zone whereby high viscosity, high VI (viscosity index) liquid hydrocarbon lubricant is produced having a branch ratio less than 0.19 and a pour point below -15°C. The process is distinguished in that internal or iso-olefins are unreactive in the oligomerization; only terminal olefinic groups participate in the coordination catalyzed oligcmerization using reduced chromium oxide on silica. Accordingly, the observation has been made that the process is potentially useful for the separation of 1-alkenes from other isomers and for the conversion of 1-alkenes, or alpha-olefins, into useful oligcroers.

The present invention provides an integrated process for the preparation of lower alkanol tertiary alkyl ethers,

particularly MTBE, or secondary or tertiary alkyl alcohols, utilizing economically advantageous separation of unreactive feedstream components.

It has been discovered that substantial improvements in the process of producing lower alkyl tertiary alkyl ethers, such as methyl tertiary butyl ether (MTBE) or methyl tertiary amyl ether (TAME) or the (Xirresponding tertiary alcohols are realized vhen the 1-alkene component of the hydrocarbon feedstream to an etherification or olefin hydration process is separated by selective oligcmerization in contact with a reduced chrcmium on a silica support catalyst producing useful hydrocarbon of higher molecular weight, such as gasoline, distillate and lube range hydrocarbons. It has further been discovered that separation of the 1-alkene component of the hydrocarbon feedstream can be accomplished in an oligomerization process integrated either upstream or downstream of the etherification or hydration step.

Mare particularly, an integrated process for the production of oxygenates comprising lower alkyl tertiary alkyl ethers and tertiary alkyl alcohols plus higher molecular weight olefins from C₄+ hydrocarbons has been found, the process comprising the steps of:

a) contacting a lower alkanol or water feedstream and a C₄+ hydrocarbon feedstream rich in iso-olefins with an acid catalyst in a reaction zone under etherification or hydration conditions to produce an effluent stream comprising lower alkyl tertiary alkyl ethers or tertiary alkyl alcohols and unreacted C₄+ hydrocarbons containing 1-alkene components;

b) separating the effluent stream and recovering the ether or tertiary alcohol component thereof;

c) passing the effluent stream component (xaitaining 1-alkene to an oligcmerization zone in contact with reduced chromium oxide on a silica support catalyst under oligcmerization conditions whereby the 1-alkene is oligomerized to the higher molecular weight olefins; and

d) separating and recovering the olefins.

In the drawings. Figure 1 is a block diagram illustrating the instant invention embodying oligcmerization downstream of etherification.

Figure 2 is a block diagram illustrating the instant invention embodying oligcmerization upstream of etherification.

The instant invention utilizes the unique capability of the oligcmerization process described herein, referred to as the HVT-PAO process, to selectively oligemerize 1-alkene without oligemerizing those alkenes containing only internal olefin bonds. The process can, therefore, preferentially convert 1-alkenes in a mixture of hydrocarbons containing other

unsaturated olefinic iscmers and alkanes to produce higher polymers of 1-alkene, otherwise referred to as polyalpha-olefins, in the form of valuable higher molecular weight olefins. These oligcmers with olefinic unsaturation can be used as starting material for detergents, additives and many other chemicals.

Following hydrogenatiαn by conventianal processes well known in the art, they also can yield useful gasoline, distillate and lube range products. When this capability of the HVI-PAO

oligcmerization process is integrated with iso-olefin

etherification or olefin hydration processes using mixed

hydrocarbon feedstock such as from an POC (fluid catalytic cracking) unsaturated gas plant containing 1-alkene, the 1-alkene is preferentially separated, enhancing the performance of the etherification or hydration processes, such as MTBE or tertiary butyl alcohol (TEA) production.

In the present invention oxygenates comprising lower alkanol tertiary allkyl ethers and tertiary alcchols plus higher molecular weight olefins from C₄+ hycirocarbons are produced from the same feedstream. The oxygenates are produced by either etherification or hydration of olefins while the higher molecular weight olefins are produced by oligomerization of 1-alkene by the method described herein. The term "oxygenates" or "oxygenate" as used herein refers to C₁-C₈ lcwer aliphatic, acyclic alcchols or alkanol and symmetrical or unsymmetrical C₂-C₈ ethers.

Olefins suitable for use as starting material in the HVT-PAO process vhich are preferentially oligcroerized when included in a feedstream to an iso-olefin etherification or hydration process include those olefins containing from 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and 1-tetradecene and branched chain iscmers such as 4-methyl-1-pentene. Also suitable for use are refinery olefinic hydrocarbon feedstocks or effluents containing alphaolefins. Typically, such feedstock will also be rich in C₄+ iso-olefins and other olefin iscmers and generally is comprised of 1-butene, 2-butene, iscbutene, 1-peπtene, 2-pentene and isoamylene and higher hydrocarbons.

The alpha-olefin oligcmers are prepared by

oligcmerization reactions in which a major proportion of the double bonds of the alpha-olefins are not isomerized. These reactions include alpha-olefin oligcmerization by supported metal oxide catalysts, such as Cr compounds on silica or other supported IUPAC Periodic Table Group VIB compounds. The catalyst most preferred is a lcwer valence Group VIB metal oxide on an inert support. Preferred supports include silica, alumina, titania, silica alumina, magnesia and the like. The support material binds the metal oxide catalyst. Porous substrates having a pore opening of at least 40 x 10^-7 mm (40 angstroms) are preferred.

The support material usually lias high surface area and large pore volumes with average pore size of 40 to 350 x 10^-7mm

(40 to 350 angstroms.) The high surface area is beneficial for supporting large amounts of highly dispersive, active chromium metal centers and to give maximum efficiency of metal usage, resulting in very high activity catalyst. The support should have large average pore openings of at least 40 x 10^-7mm (40 angstroms), with an average pore opening of >60 to 300 x 10^-7mm

(>60 to 300 angstroms) being preferred. This large pore opening will not impose any diffusional restriction of the reactant and product to and away from the active catalytic metal centers, thus further optimizing the catalyst productivity. Also, for this catalyst to be used in fixed bed or slurry reactor and to be recycled and regenerated many times, a silica support with good physical strength is preferred to prevent catalyst particle attrition or disintegration during handling or reaction. The supported metal oxide catalysts are preferably prepared by impregnatirig metal salts in water or organic solvents onto the support. Any suitable organic solvent known to the art may be used, for example, ethanol, methanol, or acetic acid. The solid catalyst precursor is then dried and calcined at 200 to 900°C by air or other oxygen-cxaitaining gas. Thereafter the catalyst is reduced by any of several various and well kncwn reducing agents such as, for example, CO, H₂, NH₃, H₂S, CS₂, CE₃SCH₃, CH₃SSCH₃, metal alkyl containing compounds such as R₃A1, R₃B,R₂Mg, RLi, R₂Zn, where R is alkyl, alkαxy, aryl and the like. Preferred are CO or H₂ or metal alkyl containing ccmpounds.

Alternatively, the Group VIB metal may be applied to the substrate in reduced form, such as CrII compounds. The resultant catalyst is very active for oligomerizing olefins at a

temperature range from belcw rocm temperature to about 250°C at a pressure of 10 kPa (0.1 atmosphere) to 34600 k pa (5000 psi.) Contact time of both the olefin and the catalyst can vary from one second to 24 hours. The catalyst can be used in a batch type reactor or in a fixed bed, continuous-flow reactor.

In general the support material may be added to a solution of the metal compounds, e.g., acetates or nitrates, etc., and the mixture is then mixed and dried at room

temperature. The dry solid gel is purged at successively higher temperatures to 316°C (600°F) for a period of 16 to 20 hours. Thereafter the catalyst is cooled under an inert atmosphere to a terrperature of 250 to 450ºC and a stream of pure reducing agent is contacted therewith for a period when enough CO has passed through to reduce the catalyst as indicated by a distinct color change from bright orange to pale blue. Typically, the catalyst is treated with an amount of 00 equivalent to a two-fold stoichicmetric excess to reduce the catalyst to a lower valence CrII state. Finally, the catalyst is cooled to rocm temperature and is ready for use. The following exairples of the H7I-PAD process

are presented merely for illustration purposes and are not intended to limit the scope of the present invention which integrates the HVI-PAD process with etherification.

Example 1

Catalyst Preoaration and Activation Procedure

1.9 grams of chromium (II) acetate

(Cr₂ (OCOCH₃) ,2H₂O) (5.58 mmole) (commercially obtained) is dissolved in 50 ml of hot acetic acid. Then 50 grams of a silica gel of 8-12 mesh size, a surface area of 300 m²/g, and a pore volume of 1 ml/g, also is added. Most of the solution is absorbed by the silica gel. The final mixture is mixed for half an hour on a rotavap at room temperature and dried in an open-dish at room temperature. First, the dry solid (20 g) is purged with N₂ at 250°C in a tube furnace. The furnace

teπperature is then raised to 400°C for 2 hours. The temperature is then set at 600°C with dry air purging for 16 hours. At this time the catalyst is cooled under N₂ to a temperature of 300°C. Then a stream of pure CO (99.99% from Matheson) is introduced for one hour. Finally, the catalyst is cooled to room temperature under N₂ and ready for use.

Example 2

The catalyst prepared in Example 1 (3.2 g ) is packed in a 9.5 mm (3/8") stainless steel tubular reactor inside an N₂ blanketed dry box. The reactor under N₂ atmosphere is then heated to 150°C by a single-zone Lindberg furnace. Prepurified 1-hexene is pumped into the reactor at 1068 kBa (140 psi) and 20 ml/hr. The liquid effluent is collected and stripped of the unreacted starting material and the lew boiling material at 7 Pa (0.05 mm Hg). The residual clear, colorless liquid has

viscosities and VI-s suitable as a lubricant base stock. Sample Prerun 1 2 3

T.O.S., hr. 2 3.5 5.5 21.5

(Time on Stream)

Lube Yield, wt% 10 41 74 31

Viscosity, mm²/s (cS), at

40°C 208.5 123.3 104.4 166.2

100°C 26.1 17.1 14.5 20.4

VI 159 151 142 143

Examole 3

A commercial chrome/silica catalyst which contains 1% Cr on a large-pore volume synthetic silica gel is used. The catalyst is first calcined with air at 800°C for 16 hours and reduced with CO at 300°C for 1.5 hours. Then 3.5 g of the catalyst is packed into a tubular reactor and heated to 100°C under the N₂ atmosphere. 1-Hexene is pumped through at 28 ml per hour at 101 kPa (1 atmosphere.) The products are collected and analyzed as follows:

Sairole C p E F

T.O.S., hrs. 3.5 4.5 6.5 22.5 lube Yield, % 73 64 59 21

Viscosity, mm²/s (cS), at

40°C 2548 2429 3315 9031

100°C 102 151 197 437

VI 108 164 174 199

These runs shew that different Cr on a silica catalyst support are also effective for oligomerizing olefins and can be used in the instant invention.

In the preferred embodiments of this invention, a lower alcohol such as methanol, ethanol, 1-propanol or isopropanol, but preferably methanol, is reacted with hydrocarbon feedstock such cis C₄ and C₄+ feedstock containing olefins, particularly iso-olefins, to produce methyl tertiary alkyl ethers,

particularly methyl tertiary butyl ether and methyl tertiary amyl ether. Alternatively, the olefins may be hydrated by reaction with water to form the correspcaιding alcohol such as tertiary butyl alcohol, 2-butanol, 2-pentanol, 3-pentanol,

3-methyl,2-butanol and the like. In the etherification reaction, the alkanol, or lower alcchol such as methanol, is generally present in an excess amount between 2 wt.% to 100 wt%, based upon iso-olefins. Excess methanol means excess methanol above the stoichicmetric equivalent amount to convert iscolefins in the hydrocarbon feedstream to methyl tertiary alkyl ethers.

Following the etherification reaction, the etherification reaction effluent stream, vhich comprises unreacted methanol, hydrocarbons including a major portion of C₄+ hydrocarbons and methyl tertiary alkyl ethers, are separated according to

fractionation and extraction techniques well known to those skilled in the art.

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 may be obtained from natural gas by other conventional processes, such as steam rearming or partial oxidation to make the intermediate syngas. Crude methanol from such processes usually contains a significant amount of water, usually in the range of 4 to 20 wt%. The etherificaticin catalyst 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, sulfσnic acid resins, phosphoric acid modified kieselguhr, silica alumina and acid zeolites. Typical hydrocarbon feedstock 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 isotutylene 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, Hydrocarbon

Proces-sinq, 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 bifunctiαnal ion exchange resin vhich etherifies and isomerizes the reactant streams. A typical acid catalyst is Amberlyst 15 sulfαnic acid resin.

MIBE and TAME are kncwn to be high octane ethers. 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 vhen 10% is added to a base fuel (R+O = 91) is about 120. For a fuel with a low motor rating (Mto = 83) octane, the blending value of MTBE at the 10% level is about 103. On the other hand, for an (R+O) of 95 octane fuel, the blending value of 10% MTBE is about 114.

Processes for producing and recovering MTBE and other methyl tertiary alkyl ethers from C₄-C₇ isoolefins 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.). Various suitable extraction and distillation techniques are known for recovering ether and hydrocarbon streams from etherification effluent.

As noted and referenced herein before, processes are also well known in the art for the production of alcohols by hydration of olefins in contact with acidic catalyst. Tertiary alcchols produced thereby are known to have high octane numbers.

Referring to Figure 1, one embodiment of the instant invention is presented integrating the HVI-PAD process downstream of the etherification process producing MTBE or a hydration process producing TEA. A C₄ or C₄+ stream 110 containing

1-alkene and iso-butene is fed to an etherification or hydration zone 115 together with methanol or water feedstream 120. The etherification or hydration effluent is separated to provide a raffinate stream 125 containing hydrocarbons including 1-alkene while MTBE is recovered in stream 130 in the case of

etherification and TEA is recovered in the case of hydration. The raffinate stream 125 is passed to HVI-PAD process

oligcmerization zone 135 vherein 1-alkene hydrocarbons are selectively converted to higher molecular olefins and, in particular, poly-1-butene liquids. The effluent from the oligcmerization zone is separated to recover oligomeric olefins 140 ilncluding poly-1-butene and a stream 145 containing unreacted C₄ or C₄+ hydrocarbons.

Referring to Figure 2, another embodiment of the instant invention is presented vzhere the HVI-PAD process is integrated upstream of etherification or hydration unit, m this embodiment the C₄ or C₄+ feedstream 210 conrtaining 1-alkene and iso-olefins is fed to the oligcmerization zone 215. The effluent is separated and a raffinate stream 220 containing unreacted iso-olefins is passed to etherification or hydration zone 225 in conjunction with methanol or water feedstream 230 while oligcmerization product is recovered in stream 235. The effluent from the etherification or hydration zone is separated to provide MTBE or TEA 240 and unreacted hydrocarbons 245.

In Figure 1, the raffinate stream from MIBE or other etherification units, containing 1-, 2-toutenes and/or butanes, is reacted over Cr/SiO₂ type catalysts to give useful liquid products. The residual C₄ stream, rich in 2-butene and/or butanes, can be used in alkylation units, or starting material for butadiene or isomerization reactor to upgrade 2-butene into mixed butenes.

In Figure 2, the mixed C. stream is first reacted ever an Cr/SiO₂ type catalyst to selectively remove 1-butene. The raffinate is then fed into a MTBE or etherification unit to remove i-butene. The residual stream is rich in 2-butene and/or butanes.

In both eipbodiments, the l-tutene is selectively removed and converted into useful liquid products over a Cr/SiO₂

catalyst. The residual 2-butene streams, usually of little use and lew value, can be isomerized into higher-value 1- or

iso-butenes, can be used in alkylation units or dehydrogenated into butadiene. These operations separate 1- and 2-butenes without complicated distillation or sorption techniques.

In both embodiments the liquid oligcmer product can be used as a starting material for additives, lubricants, gasoline or distillates.

The following examples illustrate the novel selectivity of the oligcmerization process.

Example 4

Eleven grams of 1-hexene and 10 g 2-hexenes are mixed with 1.5 g of an activated Cr on silica catalyst, prepared by chaining a catalyst obtaining 0.91% Cr and 2.12% Ti on silica at 600°C with air followed by reduction with CO at 300°C. The reaction is traced by GC which data demonstrates that 1-hexene can be selectively reacted away in the presence of other hexenes. The contents of 2-hexenes remained constant throughout the reaction. 2-hexenes are unreactive. Example 5

A catalyst, 3 grams, containing 3 wt% Cr on silica gel, calcined at 600°C with air for 16 hours and reduced with CO at 350°C for one hour, is packed in a 9.5 ram (3/8") stainless steel tube reactor. 1-Butene is fed through the reactor at 160°C, 2520 kPa (350 psi) and WHSV of 2. After 21.5 hours reaction time, 134 grams of liquid product is collected. The conversion of 1-butene to liquid is 100%. The liquid product is fractionated to give 3 fractions:

fraction 1, boiling up to 140°C/atm, 15.3 wt%, mostly octenes;

fraction 2, boiling up to 160°C/13 Pa(0.1πm Hg) , 56%, mostly C₁₂ to C₂₄ olefins;

Fraction 3, residual, 28.7 wt%, with the following visccmetric properties,

V§100°C = 28.65 mm²/s (28.65 cS) , V@40°C = 411.37 mm²/s (411.37 CS), VI = 96

Example 6

Similar to Exairple 5, except reaction temperature is 123°C. The liquid yield from 1-butene is 100%. The liquid product is fractionated to give the following fractions:

fraction 1, boiling up to 140°C/atm, 0.4 wt%.

fraction 2, boiling up to 160°C/13.3 Pa (0.1mm Hg) , 23.6 wt%, mostly C₁₂ to C₂₄ olefins

fraction 3, residual, 76wt%, with the following visccmetric prcperties

V@100°C = 70.13 mm²/s (70.13 cS) , V@40°C = 1904.92 mm²/s (1904.92 cS) , VI - 89.

While the invention has been described by specific examples and embodiments, there is no intent to limit the inventive concept except as set forth in the following

claimss

Claims

CIAIMS:

1. An integrated process for the production of lower alkyl tertiary alkyl ethers and higher molecular weight olefins from C₄+ hydrocarbons cxaiteining alpha-olefins and iso-olefins σcπprising the steps of:

a) contacting a C₁-C₈ lcwer alkanol feedstream and a feedstream comprising the C₄+ hydrocarbons containing isobutenes and 1-alkenes with an acid etherification catalyst in an

etherification zone under etherification conditions to produce an effluent stream comprising lcwer alkyl tertiary alkyl ethers and unreacted C₄+ hydrocarbons cxantaining the 1-alkene components;

b) separating the effluent stream and recovering the ether oomponent thereof;

c) feeding the effluent stream component containing 1-alkene to an oligcmerization zone in contact with reduced chrcmium oxide on silica support catalyst under oligcmerization conditions at a temperature of 90°C to 250°C to oligcmerize the 1-alkene to higher molecular weight olefins; whirein the chromium catalyst on silica support has been treated by oxidation at a temperature of 200 to 900°C in the presence of an oxidizing gas and then treatment with CO reducing agent to reduce the catalyst to a lcwer valence state; and

d) separating and recovering the higher molecular weight olefins.

2. The process of claim 1 wherein the lower alkyl tertiary alkyl ether comprises methyl tertiary butyl ether and/or methyl tertiary amyl ether.

3. The process of claim 1 wherein the hydrocarbon feedstream comprises 1-tutene, 2-butene, iso-butene and butane.

4. The process of claim 1 wherein the C₄+ feedstream contains isoamylene.

5. The process of claim 1 wherein the lower alkanol comprises between 2 and 100% stoichicmetric excess of lower alkanol selected from methanol, ethanol, 1-propanol and

isopropanol.

6. The process of claim 1 wherein the hydrocarbon feedstream comprises C₄+ olefins from an FCC unsaturated gas plant.

7. The process of claim 1 wherein the high molecular weight olefin comprises polymers and copolymers of C₄+ 1-alkene.

8. The process of claim 1 vherein the polymer comprises poly-1-butene.

9. The process of claim 1 wherein the oligcmerization conditions comprise temperature between 90 and 250°C.

10. An integrated process for the production of lower alkyl tertiary alkyl ether and higher molecular weight olefins from lower alkanol and C₄+ hydrocarbons containing alpha-olefins and iso-olefins, comprising:

a) contecting a feed stream comprising the C₄+

hydrocarbons with reduced chromium oxide on silica support catalyst under oligcmerization conditions in an oligcmerization zone whereby 1-alkene component of the feedstream is oligomerized to produce an effluent stream containing higher molecular weight olefins and unreacted C₄+ hydrocarbons;

b) separating and recovering the higher molecular weight olefins;

c) passing the unreacted hydrocarbons and lower alkanol feedstream to an etherification zone in contact with acidic etherification catalyst under etherification conditions whereby an effluent stream is produced comtaj-ning lower alkyl tertiary alkyl ether;

d) separating and recovering the ether.

11. The process of claim 10 wherein the lower alkyl tertiary alkyl ether comprises methyl tertiary butyl ether and/or methyl tertiary amyl ether.

12. The process of claim 10 wherein the hydrocarbon feedstream comprises 1-butene, 2-butene, iso-butene and butane.

13. The process of claim 10 wherein the C₄+ feedstream contains isoaitylene.

14. The process of claim 10 vftierein the lcwer alkanol comprises between 2 and 100% stoichicmetric excess of lower alkanol selected from methanol, ethanol, 1-propanol and

isopropanol.

15. The process of claim 10 vherein the hydrocarbon feedstream comprises C₄+ olefins from an POC unsaturated gas plant.

16. The process of claim 10 wherein the higher molecular weight olefin comprises polymers and ccpolymers of C₄+ 1-alkene.

17. The process of claim 10 wherein the polymer comprises poly-1-butene.

18. The process of claim 10 wherein the oligomerization conditions comprise temperature between 90 and 250°C.

19. The process of claim 1 or 10 wherein the higher molecular weight olefin is hydrogenated to produce saturated hydrocarbon.

20. An integrated process for the production of tertiary alkyl alcchols and higher molecular weight olefins from C₄+ olefinic hydrocarbons∞ntaining alpha-olefins and iso-olefins comprising the steps of:

a) contacting a water feedstream and a feedstream comprising the C₄+ hydrocarbcais with an acidic olefin hydration catalyst in a hydration zone under olefin hydration conditions whereby an effluent stream is produced comprising C₄+ tertiary alkyl alcohol and unreacted C₄+ hydrocarbons containing 1-alkene components;

b) separating the effluent stream and recovering the alcchol component thereof; c) passing the effluent stream component containing 1-alkene to an oligcmerization zone in contact with reduced chrcmium oxide on silica support catalyst under oligcmerization conditions whereby the 1-alkene is oligαnerized to the higher molecular weight olefins; and

d) separating and recovering the higher molecular weight olefins.

21. The process of claim 20 wherein the alcchol comprises tertiary butyl alcchol.

22. The process of claim 20 wherein the hydrocarbon feed-stream comprises 1-butene, 2-butene, iso-butene and butane.

23. The process of claim 20 vfoerein the C₄+ feedstream contains isoamylene and the alcchol comprises isoamyl alcohol.

24. The process of claim 20 wherein the high molecular weight olefin comprises polymers and copolymers of C₄+ 1-alkene.

25. An integrated process for the production of tertiary alkyl alcchol and higher molecular weight olefins from C₄+ olefinic hydrocarbons containing alpha-olefins and iso-olefins, comprising:

a) ccaitacting a feedstream comprising the C₄+

hydrocarbons with reduced chromiτim oxide on silica support catalyst under oligcmerization conditions in an oligcmerization zone whereby 1-alkene component of the feedstream is oligcmerized to produce an effluent stream containing higher molecular weight olefins and unreacted C₄+ hydrocarbons;

b) separating and recovering the higher molecular weight olefins; c) passing the unreacted hydrocarbons and water

feedstream to an olefins hydration zone in contact with acidic catalyst under olefins hydration conditions whereby an effluent stream is producte containing tertiary alkyl alcohol;

d) separating and recovering the alcohol.

26. The process of claim 25 wherein the alcohol comprises tertiary butyl alcohol.