KR100765669B1 - Process for the production of gasoline stocks - Google Patents

Abstract

A process for producing a gasoline stock, wherein the low molecular weight olefin (line 102) is first oligomerized and the hydrogenated oligomer (line 105) is described. The oligomerization is carried out in a single pass fixed bed boiling point reactor 10 in the first step. The oligomer (line 105) is then hydrogenated in distillation column reactor 20.

Olefin, Oligomerization, Hydrogenation, Gasoline Stock

Description

Production method of gasoline stock {PROCESS FOR THE PRODUCTION OF GASOLINE STOCKS}

The present invention generally relates to a process for producing a gasoline boiling range stock from low boiling olefins. More specifically, the present invention relates to a process for oligomerizing C ₃ to C ₅ olefins to produce C ₈ to C ₉ olefins, which are then hydrogenated to produce the desired gasoline blend stock.

Conversion of olefins to gasoline and / or distillation products is described in US Pat. Nos. 3,960,978 and 4,021,502, wherein ethylene to pentene alone or mixtures of paraffins are brought into contact by contacting olefins with a catalyst layer made of ZSM-5 type zeolites. The gaseous olefins in the range were converted to olefinic gasoline blending stock. United States Patent No. 4,227,992 Garwood and Lee was of C ₃ + olefins to mainly described operation conditions for the selective conversion of the aliphatic hydrocarbon. U.S. Patent Nos. 4,150,062 and 4,211,640 also describe a process for the conversion of olefins to gasoline components. Chang et al., In US Pat. No. 5,608,133, describe the preparation of synthetic lubricants by oligomerization of C ₂ -C ₅ olefins and subsequent hydrogenation of high boiling olefins. A liquid phase process for oligomerization of C ₄ and C ₅ isoolefins has been described in US Pat. No. 5,003,124, in which the reaction mixture is boiled to remove heat of reaction and in one embodiment further dimerization is obtained in a reactive distillation column. .

Brunelli et al., Diisobutylene 2,4, which, when hydrogenated in US Pat. No. 5,510,555, all produce 2,2,4 tri-methyl pentane (the standard for octane measurements, ie RON = 100 and MON = 100). Two isomers of 4-tri-methyl pentene and 2,4,4-tri-methyl-2-pentene have been described.

Summary of the Invention

In short, the present invention includes oligomerization of lower olefins followed by hydrogenation of oligomers. The oligomerization is preferably carried out in a boiling point reactor under mild dimerization conditions, in contrast to long chain oligomers which control the temperature by allowing the reaction mixture to absorb and boil the latent heat of evaporation. If desired, the effluent from the boiling point reactor can be fed to the distillation column reactor to ensure complete reaction of the olefins. Catalysts useful for the oligomerization reaction include acidic cation exchange resins or zeolites.

The dimer produced in the oligomerization reaction is then hydrogenated, preferably by reactive distillation. The dimer can be fed to the reactive distillation column reaction at an effective hydrogen partial pressure, such as less than 50 psia, at least about 0.1 to less than 70 psia, with the hydrogen stream. The reactive distillation column reactor is a component of the distillation structure and optionally contains a hydrogenation catalyst that hydrogenates a portion of the dimer. Within the hydrogen partial pressure as defined, more hydrogen is not used than is necessary to maintain the catalyst and hydrogenate the olefinic compound, because excess hydrogen is usually leaked out. Typical hydrogenation catalysts are Group VIII metals supported on an alumina base and include platinum, nickel and cobalt.

The term "reactive distillation" is used to describe the simultaneous reaction and fractionation in a column. For the purposes of the present invention, the term "catalyst distillation" includes fractional distillation and other methods of reactive distillation and simultaneous reaction in a column, regardless of the name applied.

The catalyst layer used in the present invention may be described as fixed, which means that it is disposed in the fixed region of the column and includes an expansion layer and a boiling layer of the catalyst. These catalysts in the bed can all be the same or different as long as they can perform the function of hydrogenation as described. Catalysts prepared as distillation structures are particularly useful in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figures are schematic flowcharts of one aspect of the present invention.

Olefinable oligomers in the present invention include propylene, butene and pentene. In particular, isobutene and isopentene (isoamylene) and linear αolefins are useful. Typically the internal linear C ₄ and C ₅ olefins are less reactive than α-olefins or iso-olefins of the same carbon number.

Oligomerization reactions of the molecule include:                 

(1) Propylene + Isobutylene → Heptene

(2) isobutylene + isobutylene → di-isobutylene

(3) n-butene + isobutylene → octene

(4) isoamylene + propylene → octene

(5) isoamylene + butylene → nonene.

The higher olefins are then hydrogenated to produce alkanes useful as gasoline blending stocks. Dimerization of isobutylene itself is particularly interesting because it produces 2,2,4-trimethyl pentane (isooctane) when the isomer of di-isobutylene is hydrogenated. Tertiary olefins are more reactive and tend to form dimers, some codimers and higher oligomers.

Preferably, in the presence of an acidic particulate catalyst or zeolite, such as an acidic cation exchange resin, at a boiling point reactor at a pressure sufficient to maintain the reaction mixture at a boiling point in the range from 120 to 300 ° F., at least part of the reaction mixture but in the vapor phase. The oligomerization reaction is carried out at. Such reactors and methods are described in US Pat. No. 5,003,124, which is incorporated herein by reference.

Given compositions, reaction mixtures will have different boiling points at different pressures, so the temperature in the reactor can be controlled by adjusting the pressure to the desired temperature within the recited ranges. The boiling point of the reaction mixture is thus the reaction temperature and the exotherm of the reaction is dissipated by the evaporation of the reaction mixture. The maximum temperature of any heated liquid composition will be the boiling point of the composition at a given pressure with additional heat predominantly causing further boyle up. The same principle is used in the present invention to control the temperature. There must be liquid, but this will cause the boy up, otherwise the temperature in the reactor will continue to rise until the catalyst is damaged. In order to avoid exotherm that will evaporate the entire reaction mixture, it is necessary to limit the amount of olefins in the feed to the reactor to about 60% of the total feed. The present invention can be used for streams containing any of a variety of olefins or mixtures thereof. The temperature should be carefully controlled to prevent the formation of trimmers and heavy products. Boiling point reactors provide this control very well on their own.

The catalyst bed in the boiling point reactor may be a fixed continuous bed, ie there may be one or more such continuous beds in the reactor sequestered by the catalyst free space, but the catalyst is loaded into the reactor in particulate form to fill the reactor or reaction zone. Can be.

The resin or zeolite catalyst is loaded into the partial liquid boiling point reactor as catalyst layer of granules. The feed for the reaction is fed to the bed in liquid phase. The layers can be horizontal, vertical or angled. Preferably the bed passes down through the bed and is perpendicular to the feed exiting through the lower end of the reactor after the reaction. The reactor is operated at high liquid hourly space velocity (5-20 LHSV, preferably 10-20) to avoid back reaction and polymerization of olefins. These conditions result in about 80-90% conversion of the olefins, and it may also be desirable to have two or possibly more reactors in series to obtain the desired conversion of the overall olefins.

The oligomer may be separated from the reactants by conventional distillation with the oligomer product removed as bottoms and the unreacted feed recovered as overhead. Alternatively, the effluent from the boiling point reactor can be fed to a distillation column reactor containing the same or similar catalysts to obtain the desired conversion and at the same time separate the product from the unreacted feed.

The oligomer is then fed to a hydrogenation zone, preferably to a distillation column reactor containing a hydrogenation catalyst. The catalytic material used in the hydrogenation process is preferably in a form which serves as a distillation packing. In general terms, the catalytic material is a component of a distillation system that functions both as a catalyst and a distillation packing, ie a packing for a distillation column having a distillation function and a catalyst function. The catalyst is prepared in the form of a catalytic distillation structure. More specifically, the hydrogenation catalyst generally comprises a Group VIII metal supported on an alumina carrier in the form of extrudates or spheres. The extrudate or sphere is placed in a porous vessel and suitably attached to the distillation column reactor to flow vapor through the bed while providing sufficient surface area for catalytic contact.

Among the metals known to catalyze the hydrogenation reaction are platinum, rhenium, cobalt, molybdenum, nickel, tungsten and palladium. Generally, commercially available forms of catalysts use supported oxides of these metals. The oxide is reduced to active form by hydrogen in the feed before or during use with the reducing agent. These metals also catalyze dehydrogenation at other reactions, most notably at elevated temperatures.

The reaction system can be described as heterogeneous because the catalyst remains distinct. Any suitable hydrogenation catalyst, for example as a main catalyst component, preferably palladium / gold, palladium / silver, cobalt / zirconium, nickel, deposited on a support such as alumina, refractory brick, pumice, carbon, silica, resin, etc. Group VIII metals of the Periodic Table of the Elements may be used alone or in combination with accelerators and modifiers.

In order to provide the desired degree of temperature and residence time control, procedures and apparatus are provided in which the reaction liquid is boiled in a distillation column reactor. Overhead is recovered and condensed as part of the condensate that returns to the distillation column reactor as reflux. The advantage of this process is that some of the selected oligomers always condense on the catalyst structure because of the constant reflux.

In a distillation column, the effectiveness of the hydrogenation procedure is the result of the condensation of a portion of the vapor in the reaction system which occludes sufficient hydrogen in the condensed liquid to obtain the required homogeneous contact between the hydrogen and the selected oligomer in the presence of a catalyst resulting in its hydrogenation It is thought to be. Evaporation of the liquid feed removes a substantial amount of exotherm of the reaction. Since the liquid is at the boiling point in the reactor, the temperature can be controlled by pressure. Increasing the pressure increases the temperature and decreasing the pressure decreases the temperature.

Several different arrangements have been described to achieve the desired results. For example, British Patents 2,096,603 and 2,096,604 describe the placement of catalysts on conventional trays in distillation columns. A series of US patents including those described above or more, in particular US Pat. Nos. 4,443,559 and 4,215,011, used catalysts as part of packing in a packed distillation column. The use of multiple layers in a reactive distillation column is also known, see, for example, US Pat. No. 4,950,834; 5,321,163; 5,321,163; And 5,595,634.

One suitable catalyst structure for hydrogenation of oligomers is a flexible, semi-open, open mesh tube filled with particulate catalyst material (catalyst component), sealed at both ends, and tightly associated with and supported by a spirally wound wire mesh screen with longitudinal axes. A tubular element, the tubular element being arranged at an angle to the longitudinal axis to form a bale as described in detail in US Pat. No. 5,431,890, incorporated herein by reference, and a flexible, semi-rigid open mesh filled with particulate catalyst material The tube element preferably has fasteners every 1 to 20 inches along the length of the tube to form a multi-linked catalytic distillation structure. The connections formed by the fasteners can be arranged regularly or irregularly. At least one tubular element on the top of the wire mesh screen, such as the defrost line, is arranged diagonally to form a bale catalytic distillation structure so that the wound structure provides a new and improved catalytic distillation structure when the wire mesh screen is wound.

Further aspects include an alternating batch multiple stack of wire mesh screens and tubular elements wound with a new bale type catalytic distillation structure. The tubular elements on the alternating layer are preferably arranged on the wire mesh screen in opposite directions with their paths staggered. Each tubular element will define an in-veil helix.

The catalyst component can take many forms. In the case of particulate catalyst materials, generally 60 to about 1 mm of powder is enclosed in a porous container such as screen line or polymer mesh. The material used to make the vessel must be inert to the reactants and conditions in the reaction system. The screen line may be alumina, steel, stainless steel, or the like. The polymer mesh may be nylon, teflon, or the like. The mesh or thread per inch of material used to make the container ensures that the catalyst is retained therein and does not pass through openings in the material. Catalyst particles or powders of about 0.15 mm size may be used, but particles of about 1/4 inch diameter or less may be used in the vessel.

The reaction conditions in the distillation column reactor should be sufficient to hydrogenate the olefin to alkanes. Pressure and temperature conditions for hydrogenating diene alone are, for example, temperatures from 150 ° F. up to 170-200 ° F. at 10-75 psig. Hydrogenation of mono olefins requires more extreme conditions of 200-350 ° F. at 30-150 psig.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings are presented in connection with a simplified flowchart of one aspect of the present invention. The feed containing the olefin or the olefin to be oligomerized is fed via flow line 102 to a boiling point reactor 10 containing catalyst layer 12 which is an acidic ion exchange resin or zeolite. In a boiling point reactor olefins react with themselves or others to produce longer chain oligomers (mainly dimers), which are removed from the reactor to the distillation column reactor 20 via flow line 105.

The distillation column reactor 20 contains a hydrogenation catalyst layer 22 suitable to act as a distillation structure. The oligomers, for example dimers, or at least a portion of them are hydrogenated to the corresponding alkanes and those with high boiling points are removed as bottoms through the flow line 108. By maintaining the pressure condition, the dimer is held in the catalyst zone 22, and the dimer can be completely hydrogenated. Unreacted olefin monomer and alkanes and hydrogen in the feed are removed as overhead via flow line 106. Overhead is condensed in condenser 114 and collected in separator 116. Hydrogen may be removed via flow line 110 and recycled to flow line 104. Some of the condensed hydrocarbons are returned via line 108 as reflux and some are removed via line 112 that may be recycled through line 102. A rectifying section 24 containing a standard distillation structure, such as a tray or packing, is provided over the catalyst bed 22. A stripping section 26 is likewise provided below the catalyst layer 22.

While other embodiments have not been presented including multiple boiling point reactors and boiling point reactors followed by distillation column reactors to achieve the desired olefin conversion, they are considered to be included in the present invention.

14.2 wt% isobutene, by using a fixed bed of a 72.7 wt% of other C ₄ and the others are mainly C ₃ and Amberlyst the C ₄ feed containing C ₅ 15 beads bed passed down to 10 to LHSV of 90 ℉ 85 Produces at least% isobutene conversion.

The total effluent from the reactor was placed in a 1 inch diameter column loaded with 10 ft of 0.5 wt% Pd on a 1/8 "Al ₂ O ₃ (alumina) extrudate, hydrogenation catalyst (Calsicat E144SDU) prepared as a distillation structure. At the top of the zone was a 2 ft stripping section containing a pall ring below the catalyst bed.The total pressure was 75 psig at 175 ° F. and LHSV 10. A heavy oligomer descended into the catalyst zone, where virtually all At a partial pressure of hydrogen of 10 psig where the oligomers (mostly dimers) are converted to alkanes recovered as bottoms, they are contacted with hydrogen supplied below the catalyst zone, with overheads of C ₃ and C ₄ and C ₅ and unreacted hydrogen.

Claims (9)

(a) under oligomerization conditions in the temperature maintained at the boiling point of the mixture within the reactor by C ₃ -C _5, at least the range from 120 to 300 ° F to form a part of the oligomers react with each other or different as those of the olefin reactor C ₃ - Feeding a hydrocarbon stream containing C ₅ olefins to a single pass forward fixed bed reactor containing an ionic acid resin catalyst; (b) feeding effluent and hydrogen from the single pass pure water fixed bed reactor to a distillation column reactor containing a hydrogenation catalyst consisting essentially of Pd on an alumina support in a distillation reaction zone; (c) simultaneously in the distillation reaction zone under simultaneous hydrogenation and distillation conditions;    (i) hydrogenating a portion of the oligomer to the corresponding alkanes by contacting the oligomer with hydrogen in the presence of the hydrogenation catalyst at a temperature of 150-350 ° F., 10-150 psig;    (ii) fractionally distilling the corresponding alkanes from other hydrocarbons and hydrogen; (d) removing the corresponding alkanes from the distillation column reactor at a point below the distillation reaction zone; (e) removing other hydrocarbons and hydrogen as overhead from the distillation column; (f) cooling the overhead to separate other hydrocarbons from hydrogen; And (g) recycling a portion of the other hydrocarbons as reflux to the distillation column reactor. delete delete delete delete delete The process of claim 1 wherein hydrogen is recovered from the overhead and recycled to the distillation column reactor. delete delete

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