Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/009—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping in combination with chemical reactions
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
  • C07C41/01—Preparation of ethers
  • C07C41/05—Preparation of ethers by addition of compounds to unsaturated compounds
  • C07C41/06—Preparation of ethers by addition of compounds to unsaturated compounds by addition of organic compounds only
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
  • C07C41/01—Preparation of ethers
  • C07C41/34—Separation; Purification; Stabilisation; Use of additives
  • C07C41/40—Separation; Purification; Stabilisation; Use of additives by change of physical state, e.g. by crystallisation
  • C07C41/42—Separation; Purification; Stabilisation; Use of additives by change of physical state, e.g. by crystallisation by distillation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/10—Process efficiency

Definitions

• the present invention concerns a process in accordance with the preamble of claim 1 for preparing tertiary methyl ether products which are used, in particular, as a components of motor fuels.
• the products contain t-amyl-methyl ether and possibly heavier tertiary methyl ethers.
• the isoolefins in pa ⁇ icular the C 5 - C 7 isoolefins of the feedstock are reacted with methanol for preparing the corresponding ethers. These ethers are removed together with the bottoms product of the distillation-reaction system and. if necessary, they are further processed in order to prepare a motor fuel component. Unreacted methanol is removed with the overhead product of the distillat ⁇ ion.
• tertiary alkyl ethers are added to the fuels.
• the oxygen-contairiing ether group of these compounds has been found to improve the combustion process in a favourable way as far as the afore-mentioned aspects are concerned.
• Suitable alkyl rert-alkyl ethers are methyl t-butyl ether (MTBE), ethyl t- butyl ether (ETBE), t-amyl methyl ether (TAME), t-amyl ethyl ether (TAEE) and t- hexyl methyl ether (THME), just to mention a few examples.
• These ethers are prepared by etherification of a monovalent aliphatic alcohol with an isoolefin. The reaction can be carried out in a fixed bed reactor, in a fluidized bed reactor, in a tubular reactor or in a catalytic distillation column.
• the feed components are reacted in the presence of a solid catalyst particles, said catalyst particles being contained in a layer which remains unmixed, because the liquid flow rates are so low that the catalyst panicles do not separate from each other. They form a so-called fixed bed.
• the flow rate of the liquid phase is so high that the catalyst particles float separately in the fluidized bed of the reactor.
• th catalyst particles can form a fixed or fluidized bed in the column.
• the particular bene which can be obtained by the catalytic distillation process is that the reaction and the separation of the products take place in the same vessel.
• the etherification reaction is an exothermic equilibrium reaction, and the maximum conversion is determined by the thermodynamic equilibrium of the reaction system.
• the maximum conversion is determined by the thermodynamic equilibrium of the reaction system.
• Ion exchange resins can be used as catalysts.
• the resin used comprises a sulfonated polystyrene/divinyl benzene based cation exchange resin (sulfonated polysty ⁇ rene cross-linked with divinylbenzene) having particle sizes in the range from 0.1 to 1 mm.
• the first one comprises fixed bed reactors, columns for product separation distillation and a methanol separation unit.
• the other alternative differs from the first one in the sense that the product distillation is replaced by a catalytic distillation unit, which substantially improves the TAME conversion.
• Ethers heavier than TAME can also be produced by all of the above mentioned processes.
• the prior art processes are hampered by certain problems.
• the overhead product of the product distillation unit contains large amounts of light hydrocarbons and. for this reason, also so much unreacted methanol that the overhead product cannot be used in an alkylation unit or directly as a gasoline component.
• the methanol must be removed first which is the reason why a separate methanol separation unit has to be included in the process.
• the methanol separation generally comprises extraction with water and methanol-water distillation.
• the present invention aims at eliminating the problems associated with the prior art by providing a completely novel process for producing tertiary methyl ethers.
• the invention is based on the concept of operating the product distillation of a catalyti distillation reactor system in such a way that the methanol which is removed with the distillate is at least substantially bound to the hydrocarbons of the distillate forming an azeotrope with them.
• the above-mentioned prior art publications concern the preparation of pure ether products.
• the present invention aims at producing ether products which as such can be used as gasoline components and which, except for the C ⁇ hydrocarbons, also contain least some of the inert hydrocarbon components of the feedstock.
• the unreacted hydrocarbons are mainly removed with the bottoms product of the distillation.
• the overhead product withdrawn from distillation substantially contains an azeotrope formed by the C 4 hydrocarbons and methanol.
• the amount of C ⁇ hydrocarbons in the distillate corresponds at least approximately to the amount of C ⁇ hydrocarbons present in the feed. In this way, an essential pan of the unreacted methanol is removed in the form of said azeotrope.
• catalytic distillation reactor system denotes an apparatus, wherein the ether product reaction and the separation of the products takes place at least partially simultaneously.
• the apparatus may comprise a conventional reactive distillation column or a distillation column combined with at least one side reactor.
• the distillation column of the reactive distillation unit is operated in such a way that methanol is heavier than the hydrocarbons at the top of the distillation column. Therefore, methanol will tend to flow downwards.
• the vapor-liquid-equilibrium between C 5 and heavier hydrocarbons and methanol is maintained at such a value that methanol is lighter than the hydrocarbon.
• This causes methanol to flow upwards from the bottom of the column.
• methanol will circulate within the distillation system between the top and the bottom of the column.
• the amount of unreacted methanol can be controlled by adjusting the amount of Q hydrocarbons in the feed so that it correlates with the amount of methanol.
• the less there are C 4 hydrocarbons in the feed the less distillate can be removed and the less methanol is removed from the process.
• C* hydrocarbons or even C ? hydrocarbons
• the methanol concentration of the bottoms product of the column can easily be reduced to as small a value as desired (even less than 100 ppm).
• the amount of methanol in the distillate will corrrespond to the amount bound by the azeotrope, only.
• the composition of the azeotrope and, thus. the amount of removed methanol depends on the hydrocarbon composition of the overhead product and the operating pressure of the reaction. If C 4 hydrocarbons make up the main part (over 90 %) of the overhead product, there will remain some 0.1 to 5.0 % by weight of methanol depending on the distillation pressure and the amount of C 5 hydrocarbons. The more C 5 hydrocarbons are included in the overhead product, the more methanol will be removed with it (there may be less than 90 % by weight of the
• the reactive distillation system comprises a distillation column which is in fluid contact with at least one side reactor conraining a catalytic reaction bed.
• the side stream flow can be effected as a forced circulation by using a pump or by thermosiphon.
• the location of the drawoff from the column to the side reactor is selected such that the vapour-liquid equilibrium ratio (the K-value) o methanol is smaller than 1 on the trays above it.
• the reaction product containing methanol is returned from the side reactor to the column and it is fed to a tray having methanol K-value greater than 1.
• methanol get more enriched in the vapor phase than do the hydrocarbons.
• the side stream makes up 40 to 90 %, typically abou from 60 to about 70 % of the total liquid flow within the column.
• the use of a side reactor is preferred for instance for the reason that the conditions prevailing in the distillation column can be influenced by changing the drawoff location of the side stream and bv feedine more methanol to the reaction bed.
• the invention can also be applied to a conventional catalytic distillation reactor. It is operated in the same way as a side reactor process. The only difference is that the methanol consuming reaction takes place within the column.
• the overhead product obtained can be forwarded to a MTBE unit. Since it contains some impurities (C 5 hydrocarbons, as far as the MTBE process is concerned), the overhead product can be introduced either in the feed of the
• the C 5 hydrocarbons remain in the MTBE product, or to the methanol washing unit of the MTBE unit. In the latter case the C 5 hydrocarbons end up in the raffinate stream of the MTBE unit (which contains mainly C 4 hydrocar ⁇ bons).
• the overhead product of the distillation can - because it contains only minute amounts of methanol and because the overhead is very small compared to the feed - also be combined with the bottoms product of the distillation in order to form a gasoline component. If necessary, the mixture is subjected to an additional treatment.
• the C 4 hydrocarbon content of the feed is, however, deliberately kept so small that the mixture of the overhead and the bottoms products can be used as such as a component of motor fuels.
• the hydrocarbon feedstock may, for instance, be a hydrocarbon fraction containing isoolefins. such as a hydrocarbon cut of a cat cracker, containing a mixmr of isoolefins.
• the prereactors consist of two reactors filled with ion exchange resin beds. The reactors can be fixed or fluidized bed or mbular reactors. The reactors may be arranged in series, as shown in the figure, or in parallel.
• prereactors If there are more than tw prereactors they may also be arranged in series/parallel. Because of the reaction there is a temperature rise in the prereactors in the range from about 5 to about 15 °C depending on the efficiency of the reactor insulation. From the prereactors the mixmr is conducted to distillation column 3. At the bottom of the distillation column there is steam reboiler 4. The distillation coiumn can be a packed column or one provided wit valve, sieve or bubble-cap trays. The overhead of the column is removed via a condenser 9 to a reflux drum 10, from which the overhead is removed by means of a pump 11. A pan of the overhead is forwarded to further processing, for instance to a
• the MTBE process and a part thereof is returned to the column.
• TAME and heavier ethe are removed with the bottoms product.
• the bottoms product also contains unreacted C 5+ hydrocarbons.
• the reflux ratio of the column is preferabl from about Vi to 200. Even greater ratios can be used in pilot plant equipments. According to the invention, the reflux ratio is adjusted so that the distillate amount removed from the process at least substantially corresponds to the amount of C 4 hydrocarbons of the feed.
• a side reactor system which consists of three reactors 5, 6, 7 in series.
• the reactors can, if desired, be replaced b one larger reactor.
• the reactors can be fixed or fluidized bed reactors or mbular reactors, as mentioned above in the general part of t description.
• the side reactors are fed with a liquid stream taken from the column. Th pressure of the liquid stream is increased by pump 8.
• the side stream is preferably taken from a tray which is located below trays having methanol K-values less than 1.
• Additional methanol can, if needed, be fed to the side reactor feed before the side reactor.
• the reactor feed can be cooled to the reaction temperamre before the side reactor. Due to heat losses the temperature rises only by a few degrees in the side reactors. From the side reactor system 5 to 7 the liquid flow is routed back to column 3. It is then returned to a plate having a K-value greater than 1.
• the reactor effluent enters the column at a location below the feed coming from the prereactors 1, 2.
• the aim of this arrangement is to make the column 3 operate in such a manner that the methanol in the overhead product is bound to the C 4 hydrocarbons in the form of an azeotrope.
• the apparatus configuration depicted in figure 1 was used.
• the inner diameter of the prereactors 1 and 2 was 102.3 mm and their lengths were 1500 mm. They were filled with the catalyst Dowex ® M-32 supplied by Dow Chemicals Inc.
• the catalyst comp- rises an acid sulfonated polystyrene/divinyl benzene based cation exchange resin.
• the inner diameter of the distillation column 3 was 160 mm. its height was 11.000 mm and it was equipped with packings. There were 6 beds of packings.
• the three side reactors 5 to 7 were arranged in series and each of them had an inner diameter of 154.1 mm. and a height of 1,150 mm. These reactors were also filled with the catalyst Dowex ® M-32.
• the hydrocarbon feed rate was 30 kg/h. Its composition is shown in Table 1. The table also indicates the amounts of methanol feed. The methanol and the hydrocarbon feed were mixed together and heated to 58 °C. Then the mixmre was conducted through prereactors 1 and 2. which caused the temperature to increase by 9 °C. From the prereactors the mixmre was conducted to the distillation column 3, the feed point being situated between the third and the fourth packed bed. The temperature of the distillation column was 40 °C at the top and 95 °C at the bottom, the operating pressure being 400 kPa.
• a sidestream was withdrawn from the column at a point between the second and the third packed beds.
• the temperature of said sidestream was 70 °C. It was cooled to 60
• TAME terr-amyl methyl ether
• THME rerr-hexyl methyl ether
• TAOH t ⁇ .rr-amyl alcohol
• DME dimethvl ether

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1992
  • 1992-03-18 FI FI921174A patent/FI92319C/fi active
• 1993
  • 1993-03-18 WO PCT/FI1993/000098 patent/WO1993019032A1/en active IP Right Grant
  • 1993-03-18 ES ES93906635T patent/ES2130255T3/es not_active Expired - Lifetime
  • 1993-03-18 JP JP5516304A patent/JPH07504907A/ja active Pending
  • 1993-03-18 DE DE69324580T patent/DE69324580T2/de not_active Expired - Lifetime
  • 1993-03-18 CA CA002132318A patent/CA2132318C/en not_active Expired - Lifetime
  • 1993-03-18 BR BR9306110A patent/BR9306110A/pt not_active IP Right Cessation
  • 1993-03-18 AU AU37535/93A patent/AU3753593A/en not_active Abandoned
  • 1993-03-18 EP EP93906635A patent/EP0643680B1/en not_active Expired - Lifetime
• 1994
  • 1994-09-16 US US08/305,920 patent/US5536886A/en not_active Expired - Lifetime

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