WO1994000411A1 - Procede et appareil pour produire des ethers tertiaires - Google Patents

Procede et appareil pour produire des ethers tertiaires Download PDF

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Publication number
WO1994000411A1
WO1994000411A1 PCT/FI1993/000266 FI9300266W WO9400411A1 WO 1994000411 A1 WO1994000411 A1 WO 1994000411A1 FI 9300266 W FI9300266 W FI 9300266W WO 9400411 A1 WO9400411 A1 WO 9400411A1
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Prior art keywords
reactor
bed
section
catalyst
reactor vessel
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PCT/FI1993/000266
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English (en)
Inventor
Isto Eilos
Juhani Aittamaa
Juha Jakkula
Original Assignee
Neste Oy
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Application filed by Neste Oy filed Critical Neste Oy
Priority to AU43294/93A priority Critical patent/AU4329493A/en
Publication of WO1994000411A1 publication Critical patent/WO1994000411A1/fr

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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/20—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with liquid as a fluidising medium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
    • B01J8/26—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with two or more fluidised beds, e.g. reactor and regeneration installations

Definitions

  • the present invention relates to a process according to the preamble of claim 1 for producing tertiary alkyl ethers from isoolefins and alcohols.
  • the invention also relates to an apparatus according to the preamble of claim 9 for producing tertiary ethers and to a method according to the preamble of claim 24 for operating such an apparatus.
  • the apparatus according to the invention comprises a contiguous and elongated reactor vessel filled with cation exchange resin, the longitudinal axis of said reactor vessel being essentially vertically aligned and said reactor vessel having an inlet nozzle for feed of initial reactants and an outlet nozzle for removal of reaction products.
  • the present invention in particular relates to the production of methyl tert-butyl and ethyl tert-butyl ethers (hereinafter called MTBE and ETBE, respectively) as well as tert-amyl methyl and tert-amyl ethyl ethers (hereinafter called as TAME and TAEE, respectively).
  • MTBE and ETBE methyl tert-butyl and ethyl tert-butyl ethers
  • TAME and TAEE tert-amyl methyl and tert-amyl ethyl ethers
  • the etherification reaction of isoolefin with alcohol is exothermic (heat releasing) by nature.
  • the choice of the reactor type with mass production in mind can be any of the following: fixed-bed reactor, tubular reactor, fluidized-bed reactor or reactive distillation reactor.
  • the latter has lately been favoured to an increasing breadth. This is because distillation provides reaction of the reactants and separation of reaction products therefrom simultaneously.
  • Such a property is advantageous in terms of reaction kinetics as the process involves an equilibrium reaction in which the maximum conversion is determined by the thermodynamical equilibrium of the reaction system. So, when MTBE for instance is produced by the conventional way of combining a fixed-bed reactor with distillation separation of the product, typically approx.
  • the process catalyst employed is a sulfonated polystyrene/divinylbenzene-based cation exchange resin having a particle size of 0.1 to 1 mm typical. Owing to channelling of the flows, a particle of this size exhibits unsatisfactory hydrodynamics in a large, industrial-scale distillation unit, which necessitates the use of a larger catalyst charge. However, a large catalyst charge only worsens the above-mentioned channelling problem. Therefore different types of bag/sock systems have been developed, and attempts have been made to shape the catalyst particles identical to the packing pieces. Of the latter approach, the only industrially implemented application is realized by NPO Yarsintez and is disclosed in U.S. Patent Specification No. 3,965,039.
  • Another significant problem of catalytic distillation is associated with catalyst charge change. Because the catalyst is located within the distillation column, changing catalyst charge is a significantly more complicated operation than in a conventional fixed-bed reactor and cannot be performed on-line during run. This problem can be alleviated through the use of a prereactor that acts as a guard by absorbing the catalyst poisons and is provided with an easier catalyst charge change facility.
  • the prereactor of the reactive distillation stage is conventionally operated with an alcohol-lean mixture. In a conventional process having typically two prereactors in series, the process is usually run with a slightly alcohol-rich mixture.
  • the hydrocarbon stream is fed into the prereactor maximally concentrated with respect to the isoolefm.
  • the prereactor employed in the process is preferably a fixed-bed reactor provided with a recycling facility, or alternatively, a tubular reactor provided with cooling.
  • the prereactor can also be a fluidized-bed reactor. Such an embodiment is described in the DE Published Patent Application No. 2,944,914.
  • a fluidized-bed reactor the catalyst is fluidized by the flow of the hydrocarbon feedstock in liquid phase.
  • the flow rate required for fluidization is maintained by recycling. If the feedstock flows contain catalyst poisons in significant amounts, the fluidized-bed reactor can be utilized for removal of such adverse compounds before the process flow enters the reactive distillation column.
  • the use of a fluidized-bed reactor also offers the important benefit that the catalyst charge can be changed continuously during run. Moreover, control of temperature gradients in a fluidized-bed reactor is more readily possible than in any other reactor type.
  • the invention is based on the concept of performing the reaction of isoolefins with alcohol at least partially in an essentially vertical, contiguous reaction vessel having a lower section suited for formation of fluidized bed and an upper section suited for formation of a fixed reaction bed.
  • the fixed reaction bed is here obtained by limiting the superficial velocity of the liquid flowing through the reactor so that said velocity at the upper section of the reactor remains below the minimum fluidization velocity.
  • the change of the catalyst contained in the fixed bed can be carried out by temporarily decreasing the flow velocity sufficiently to allow the catalyst particles to fall by gravity from the fixed bed to the lower section of the reactor, wherefrom the spent catalyst is unloaded as necessary and replaced by new catalyst. Conversely, the catalyst particles falling to the lower section of the reactor can be left there to form the fluidized bed.
  • the whole solid particle bed is fluidized, which means that the flow velocity at each point of the reactor body is higher than the minimum fluidization velocity.
  • the flow velocity in the upper section is smaller than the minimum fluidization velocity of the particle mixture contained therein.
  • the volume of the upper section is in the range from about 20 to about 95 % of the total volume of the reactor.
  • the upper section makes up 40 to 80 %, preferably about half or more of the entire reactor volume.
  • the minimum fluidization velocity depends on the avarage particle size. According to the invention, the minimum fluidization velocity will remain higher than the linear flow velocity of the liquid flowing through during the process.
  • the lower section is preferably connected to the upper section by a conical expansion section.
  • the cone angle is 1 ° to 45°, preferably from about 5° to about 30°.
  • the outlet nozzle is fitted in the upper part of the reactor above the fixed bed. Therefore, the product removed from the reactor will contain only small amounts of catalyst particles, if any.
  • the apparatus according to the invention for producing tertiary ethers is characterized by what is stated in the characterizing part of claim 9 and the method according to the invention for operating the claimed apparatus is characterized by what is stated in the characterizing part of claim 24.
  • any reactor preceding the actual product separating distillation stage in the process is called a prereactor whether or not the product separation by distillation following the preceding reactor takes place by reactive distillation.
  • the product obtained from such a prereactor need not be separated by distillation from the hydrocarbon stream, since both the product and the hydro-carbon stream are directly suited for use as end product components (namely, as TAME and TAEE are concerned, said reaction products and the C 5 hydrocarbon stream are suitable as motor gasoline components).
  • Reactants used in the production of tertiary ethers are isoolefins containing 4 to 7 carbon atoms, such as isobutene, isopentene, isohexene and isoheptene or hydrocarbon streams containing mixtures thereof, combined with lower alcohols (that is. alcohols containing 6 carbon atoms or less) such as methanol, ethanol, propanol, etc.
  • the hydrocarbon feedstock also frequently contains n-olefins and saturated hydrocarbons.
  • particle (such as an ion-exchange resin or catalyst particle) in the context of the present patent application refers to particles having a suitable bead size for liquid fluidization.
  • the acid cation exchange resin employed as catalyst according to the invention has a bead size in the range from 0.01 to 10 mm, preferably approx. from 0.1 to 1 mm.
  • reaction bed refers to a space in which the catalyst and the liquid are contacted and so terms "reaction bed” and "reaction layer" are used
  • liquid flow velocity or the superficial liquid velocity (average velocity) is defined as the volume flow rate of the liquid divided by the cross section of the empty column.
  • reaction zones hereinafter refer to such expressions as "at least one single reaction zone” and "at least one second reaction zone”, which must be understood to indicate that according to the invention the reactor can be provided with a plurality of subsequent liquid-fluidized and fixed beds, respectively.
  • a fluidized bed can be divided into subsections with the help of flow redistributors is known in the art for example from the textbook Kunii, D. and Levenspiel, O., Fluidization Engineering, 2nd Ed. (1977), Robert E. Krieger Publishing Co. New York, pp. 26 - 34.
  • This invention optimizes the flow conditions in MTBE/ETBE/TAME/TAEE processes for the first reactor preceding the process stage of product separation by distillation so that the catalyst in said reactor is present in both the fluidized bed and fixed bed phases.
  • the reactor bottom is preferably provided with a catalyst bed exhibiting a high expansion factor (over 50 %) and a high degree of mixing, while the catalyst bed above this bed has the properties of a conventional liquid-fluidized bed. namely a normal expansion factor (20 to 30 %) and a moderate degree of mixing.
  • the upper section of the reactor is provided with a fixed catalyst bed and, in order to achieve high conversion rates, the volume of the upper section is large in comparison to the lower section..
  • All these layers can in principle be implemented in said reactor either as single or separate layers.
  • the essential requirement according to the invention is, however, that the reactor construction must be capable of supporting a normal liquid-fluidized bed, and above this, a reaction bed functioning at least essentially as a fixed bed.
  • the lower section and the upper section of the reactor are preferably filled with the same type of catalyst, typically the particles of the above-described cation exchange resin such as is used in a conventional manner in state-of-the-art methods for producing tertiary ethers.
  • the lower section is joined to the upper section via an expanding section, the cross-sectional area of the reactor vessel increasing above the expanding section so much as that the superficial velocity of the liquid entering the upper section from the lower section falls below the minimum fluidization velocity.
  • the expanding section comprises for instance a collar section shaped as a truncated cone with a cone angle of 1° to 45°, preferably 5° to 30°. Then, the cross-sectional area of the reactor vessel at the upper section is approx. 2- to 10-fold the reactor vessel cross-sectional area at the lower section.
  • the upper section in this embodiment is so spacious that it incorporates at least a portion of the expanding section.
  • the art conventionally employs gas-fluidized-bed reactors which have an expanded upper section
  • the reactor upper section performs a function different from that in the present invention
  • the expanding section has not been designed for forming and maintaining a fixed bed, but rather, its function is to minimize the carry-over of entrained particles from the reactor.
  • the carry-over of particles from the bed becomes no problem as the fluidization by its nature does not take place via intense bubble formation, but instead, the bed upper surface is entirely smooth. Then, it is possible to utilize the expanding section effectively as the expansion space of the bed.
  • the superficial velocity of the liquid entering the upper section is reduced below the minimum fluidization velocity by derouting at least a fraction of the liquid flow leaving the fluidized bed into an external recycling loop. Therefore, an inlet nozzle of the recycling line is adapted above the lower section of the reactor vessel, said inlet nozzle permitting recycling of at least a fraction of the product mixture passing through the lower section back to the inlet nozzle of the initial reactants.
  • the recycling of the liquid flow through the liquid-fluidized bed simultaneously improves conversion in comparison to a once-through fixed bed having heat gradient problems, thus justifying the use of recycling also in the embodiment described above.
  • the superficial liquid mixture velocity is reduced after the fluidized bed to a value which is approx. from 10 to 40 %, preferably approx. 30 to 35 %, of the superficial velocity in the fluidized bed.
  • the reactor can have a circular or essentially square cross section. This design rule applied to both above-described embodiments. At low process pressures a square or circular cross section offers both technical and economical benefits, while a reactor vessel with circular cross section is preferable at high process pressures.
  • the lower and upper sections are separated from each other by means of a flow distributor that performs homo-genization of the liquid flow over the entire cross section of the reactor.
  • an esterification reaction producing tertiary alkylethers such as MTBE, ETBE, TAME or TAEE is exothermic, whereby temperature increase reduces the equilibrium constant of the reaction, and thereby, the theoretical maximum conversion of the reaction. Close to the reaction equilibrium, the presence of the product slows down the reaction rate. Consequently, the reaction proceeds less vigorously than in the situation when the product is absent, that is, in the initial phase of the reaction.
  • a high bed degree of mixing in this stage is desirable. In a fluidized-bed reactor this is accomplished by way of a high superficial velocity of the fluidizing liquid.
  • the reaction mixture leaving the fluidized bed is cooled prior to its entry into the fixed bed.
  • the fluidized bed of the reactor lower section or alternatively, the space above this is provided with a heat exchanger, for instance a tubular heat exchanger, which simultaneously can perform a flow distributor.
  • the bottom section of the reactor vessel is provided with catalyst inlet and outlet nozzles. Through these nozzles the ion exchange resin can be both fed into the reactor vessel and unloaded therefrom, respectively.
  • a method is provided for operating such an apparatus, in which method the reactor vessel is first loaded with a sufficient charge of catalyst particles to form two reaction beds.
  • the reactor vessel lower section is filled via the reactor vessel inlet nozzle with a liquid mixture of the initial reactants to be reacted, while simultaneously adjusting the liquid flow rate with the help of a flow control element, which is installed to the pipeline leading to the inlet nozzle, to such a high level that the catalyst particles contained in the reactor vessel lower section become entrained thus forming a fluidized bed.
  • a flow control element which is installed to the pipeline leading to the inlet nozzle, to such a high level that the catalyst particles contained in the reactor vessel lower section become entrained thus forming a fluidized bed.
  • the superficial liquid velocity is further set to such a high level that excess fraction of the catalyst is carried over with the liquid mixture flow to the reactor vessel upper section.
  • the superficial liquid mixture velocity in the reactor vessel upper section is arranged to fall below the minimum fluidization velocity, whereby a fixed bed in formed therein.
  • the catalyst was not found to circulate between the fluidized-phase and fixed-phase beds. This offers the benefit that most of the catalyst poisoning can occur only in the fluidized bed contained in the reactor lower section. Therefore, only this fraction of the catalyst charge need be entirely changed during regular catalyst change.
  • the fraction of the catalyst contained in the fixed bed can be transferred to the fluidized bed zone during the catalyst change, or alternatively, in conjunction with process run.
  • Catalyst change occurs via a catalyst unload nozzle adapted to the lower section of the reactor vessel that can be opened during catalyst change. By using a smaller volume of the catalyst unload compartment, the amount of unloaded catalyst can be limited to the volume of said compartment, the rest of the catalyst remaining in the reactor.
  • the liquid flow in the reactor is stopped for 1 to 30 min (typically about 5 minutes), whereby the catalyst contained in the reactor upper section falls down by gravity.
  • the liquid flow rate in the reactor is slowly increased by recycling of the liquid above the minimum fluidization velocity until the desired amount of catalyst becomes entrained thus expanding into the reactor upper section to form a fixed bed there. Subsequently, a portion of new catalyst is fed into the reactor and the liquid flow rate is reduced to the desired fluidization velocity.
  • the invention also provides a process for producing tertiary alkyl ethers from an isoolefin or mixtures thereof and from at least one aliphatic alcohol. According to the method the materials participating in the reaction are processed into a liquid mixture which is fed into the above-described reaction apparatus where the olefins and the alcohol are reacted.
  • the invention offers significant benefits.
  • the expanded reactor top performs as an effective expansion space for the fluidized bed as during an abrupt bed expansion in a disturbance situation for instance, this zone provides rapid reduction of superficial liquid velocity, whereby the fluidized-bed voidage is reduced.
  • this zone provides rapid reduction of superficial liquid velocity, whereby the fluidized-bed voidage is reduced.
  • the total volume occupied by the catalyst bed is reduced.
  • the present reactor provides higher conversion rates and a product containing less entrained catalyst particles (usually there is only a minute amount of catalyst particles in the product, if at all).
  • the reactor lower section can be run at a higher temperature than the reactor upper section
  • Figure 1 shows the diagrammatically the truncated cone to which reference is made in conjunction with the explanation of the theoretical background for the invention
  • Figure 2 shows diagrammatically a prior-art fluidized-bed reactor
  • Figure 3 shows diagrammatically a first embodiment of a fluidized/fixed-bed reactor according to the invention
  • Figure 4 shows diagrammatically the above-mentioned first embodiment provided with a sidestream drawoff and associated recycling circuit
  • Figure 5 shows a reactor similar to that illustrated in Fig. 3 complemented with a heat exchanger
  • Figure 6 shows a reactor similar to that illustrated in Fig. 4 complemented with a heat exchanger
  • Figure 7 shows diagrammatically a second embodiment of a fluidized/fixed-bed reactor according to the invention.
  • Figure 8 shows the process schematic for a combination catalyst charge load and unload arrangement adapted to the embodiment illustrated in Fig. 3.
  • Liquid flow upward through a solid particles layer can take place at a low superficial velocity without moving grain particles if the density of the particles is greater than the liquid density as is the case in the examples to be described below.
  • the superficial velocity is increased, the particles commence a motion in confined areas and the bed layer volume will be expanded. At a sufficiently high flow rate the particles will be entrained in the liquid flow.
  • the frictional force acting between the particle and the liquid flow that is, the fluidization flow, overcomes the particle weight, thus cancelling the vertical compressive force between superimposed particles, and the pressure drop over the layer becomes equal to the effective weight of the particles per unit area.
  • the superficial liquid velocity at the start of the above-described phase is called the minimum fluidization velocity.
  • a fluidized bed When the flow rate is increased in the liquid-fluidized bed so as to exceed the minimum fluidization velocity, the fluidized bed will be expanded homogeneously and the particle concentrations in different points of the bed will be equalized.
  • Such a fluidized phase is called a smooth, homogeneous, or simply, liquid-fluidized phase.
  • gas-fluidized and liquid-fluidized beds An essential dissimilarity between gas-fluidized and liquid-fluidized beds is the large volume difference between the fluid bubbles (that is, gas bubbles and liquid bubbles).
  • gas fluidization a significant fraction of the fluidizing gas tends to rise through the fluidized bed in the form of large-volume bubbles with particles following in its wake; simultaneously, the flow is channelled.
  • the upper surface of the gas-fluidized bed is very unstable, and entrained particles will also be found above the bed upper surface.
  • Such a fluidized phase is denoted by its character as aggregative, heterogeneous, bubbling, or gas-fluidized phase.
  • Liquid fluidization In liquid fluidization the bubbles remain very small, the fluidized bed upper surface is relatively smooth, and no significant amount of entrained particles will be found above the fluidized bed upper surface provided that the superficial liquid velocity is maintained below the free-fall settling velocity of the particles.
  • Liquid fluidization conventionally uses a flow rate capable of achieving 5 to 50 % expansion of the bed. Typically the expansion is in the order of approx. 20 to 30 % . Such a low bed expansion fails to attain complete mixing of the bed solids in reactors with a large height/diameter ratio as is the case in the examples to be described below.
  • the bed exhibits a distinct temperature gradient, and the larger particles will be segregated on the bottom so that the large particles are found at a higher probability close to the flow distributor on the reactor bottom than on the upper surface of the fluidized bed.
  • the reactor Owing to turbulence occurring in the bed. the reactor must be considered a mixing reactor in which any reasonable catalyst charge fails to achieve as high conversion as is possible in a fixed bed reactor.
  • a fixed bed reactor used for production of MTBE for instance, can achieve a 80 to 90 % isobutene conversion with a reasonable size of catalyst charge, while a fluidized-bed reactor operated in similar conditions achieves 70 to 80 % conversion only.
  • a combination fluidized/fixed bed is called a semifluidized bed.
  • the upper section of a liquid-fluidized bed can be provided with a fixed bed by equipping the upper section of the fluidized bed with a particle disengaging separator screen that permits the flow of the liquid alone, while the entrained particles are packed against it.
  • the improvement over prior-art techniques is therein that the fixed bed is achieved by reducing the superficial velocity of the liquid exiting the fluidized-bed section to a value below the minimum fluidization velocity. According to a preferred embodiment of the invention, this end is attained by expanding the reactor vessel cross sectional area at the upper section of the bed.
  • m pa total mass of particles in the fixed-bed section
  • h ist height of initial fixed bed for zero liquid flow rate
  • h pa height of fixed-bed section formed by upward build-up against particle separator screen
  • A fixed bed cross-sectional area
  • ⁇ p density of a single particle
  • a semifluidized bed is achieved by reducing the superficial liquid velocity below the minimum fluidization velocity. This end is advantageously attained by making fluidization occur in an upward expanding conical reactor in which the superficial liquid velocity is reduced from the bottom upward. As the superficial liquid velocity changes as a function of the fixed-bed height, the voidage of the fluidized-bed section is not constant.
  • fluidization is next examined in a truncated cone with circular cross section, bottom radius r 0 and the walls expanding upward so as to form an angle ⁇ with vertical.
  • the cross-sectional area and the expansion factor are functions of height level within the fluidized bed.
  • the cross-sectional area is related to the height level by:
  • V liquid volume flow rate
  • the bed upper section behaves as a fixed bed.
  • the height of the bed section can be solved by replacing the term h of Eq. 19 by the height obtained from Eq. 14 (i.e., the term v mf in Eq. 14 is replaced by the superficial liquid velocity at which the bed starts to expand) and then
  • FIG. 2 shows diagrammatically a conventional reactor tube 21 operated in the fluidized-bed state.
  • the reactor is typically employed as prereactor in ether production.
  • the alcohol and olefin components are first combined into a mixture which is fed with the help of a reactor feed pump 22 into the reactor 21.
  • the reaction mixture is heated by means of a heat exchanger 23.
  • the bed expansion factor can be, for instance, in the range from 5 to 50 % and a suitable superficial liquid velocity is set by adjusting the output of the pump 22.
  • a portion of the reactor exit flow is routed to a catalytic product-separating distillation process, for instance, while the remaining portion is recycled to the inlet nozzle of the reactants in order to improve conversion.
  • the recycling line incorporates a heat exchanger 24 for the cooling of the recycled portion of the product.
  • FIG. 3 shows diagrammatically a first embodiment of the invention. Except for the reactor, the process layout of this embodiment is implemented using the above-described conventional techniques. Accordingly, in this embodiment the liquid reactant mixture is fed via a pump 32 and an optional heat exchanger 33 and an inlet nozzle 30A to the reactor 31, wherefrom the product mixture is removed via an outlet nozzle 30B. A portion of the product mixture is recycled via a heat exchanger 34 back to the inlet nozzle.
  • the reactor is a reactor tube similar to that employed in the above-described example in having a fluidized bed 35, while, however, its top is provided with a conical expanding section 37, and above this, a second reaction section 36 with a cross-sectional area larger than that of the reactor center section, said second reaction section being capable of forming a fixed bed.
  • the cone angle of the conical expanding section is typically approx. from 5° to 30°, while in principle it can vary in the range 1 ° to 45°.
  • the expansion factor of the fluidized bed is 5 to 50 %, typically approx. 20 to 30 %, and it is set by adjusting the output of the pump 32.
  • the reactor bottom section is provided with a flow distributor 38 by means of which the liquid flow is divided evenly over the reactor cross section.
  • the flow distributor can be, for instance, a perforated plate dimensioned according to normal fluidized bed fluid distributor design rules.
  • the sizes of holes in the flow distributor must be such that permit downward flow of catalyst particles at shutdown of reactor flow.
  • the bottom of the reactor 31 is shaped into a conical expanding section 39. This shaped form of the reactor bottom achieves good mixing and eliminates settling of large particles on the flow distributor plate.
  • the cone angle of the conical expanding section 38 is here 5° to 60°, preferably approx. 5° to 30°.
  • the flow rate required in the reactor is determined by the maximum particle size of the catalyst and the expansion factor of the bed.
  • the superficial liquid velocity must be higher than the minimum fluidization velocity for said particle size, and the bed expansion in the conical expansion section 39 (at the height of the flow distributor) computed for the average particle size should be in the range from 50 to 150 %, typically approx. 70 %.
  • the cone angle (full angle) should be 1 ° to 45°, typically approx. 15°.
  • Figure 4 shows an alternative embodiment of the above-described implementation, this embodiment having a flow distributor 47 placed in the reactor 41 between the fluidized bed 45 and the fixed bed 46. As shown in the diagram of the figure, this embodiment has an drawoff nozzle 48 for liquid recycling adapted above the fluidized bed 45.
  • the recycling line has a heat exchanger 44, which can be used for cooling the liquid mixture if necessary.
  • the product mixture received from the fixed bed 46 is, however, routed entirely as such to further processing.
  • this approach achieves a slightly higher conversion than such a reactor in which the entire volume of liquid passed through the reactor is recycled to maintain fluidization.
  • the achievable gain in the conversion percentage is typically in the order of 5 to 20 % -units depending on the processed product, fraction of catalyst charge in the fixed bed and reaction temperature in the fixed bed.
  • a cyclone not shown
  • a filter connected to the drawoff nozzle in order to reduce the slurry concentration of the sidestream to a sufficiently low level (5 to 40 %) for pumping with conventional pumps.
  • a reactor equipped with a sidestream drawoff is operated as follows:
  • the superficial liquid velocity in the reactor is slowly increased above the minimum fluidization velocity with simultaneous recycling of the liquid through the reactor up to a velocity achieving the expansion of a desired fraction of the catalyst charge into the fixed-bed section 46 in the reactor upper section,
  • a flow distributor 47 placed in the reactor upper section provides a catalyst-void region between the fixed-bed section 46 and the fluidized-bed section 45.
  • the sidestream drawoff is located in this region.
  • cooling in a fluidized-bed reactor can be achieved by providing the bed with heat transfer tubes.
  • this approach fails to achieve a temperature gradient in the desired direction.
  • a further desirable property is a possibility of minimizing the fraction of catalyst to be replaced during catalyst change.
  • catalyst deactivation is mainly caused by catalyst poisons entering along the reactant feed lines. Therefore, the fraction of catalyst directly encountering the feed stream is advantageously limited. Isolating the catalyst charge in a fluidized-bed section in different fractions requires the use of flow distributors within the bed. However, if the perforated separator plate placed in the bed has a too low pressure drop, internal recirculation of the catalyst particles past the separator screen cannot be prevented.
  • Figs. 5 and 6 show two alternative heat exchanger constructions.
  • the reactor arrangement shown in Fig. 5 corresponds to that illustrated in Fig. 3 with the exception that a tubular heat exchanger 57 is adapted within the fluidized-bed section 54 of the reactor 51.
  • the process flow passes through the tubes of the heat exchanger 57 which also act as intermediate distributor in the fluidized-bed section. Cooling water is pumped through the cool side of the heat exchanger.
  • the reactor arrangement shown in Fig. 6 corresponds to that illustrated in Fig. 4 with the exception that a tubular heat exchanger 67 is adapted within the fluidized-bed section 65.
  • the function of the heat exchanger is controlled by a temperature controller 68.
  • the final step of the reaction is preferably performed using a low degree of mixing.
  • the degree of mixing can be lowered according to the invention by reducing the superficial liquid velocity below the minimum fluidization velocity, which is attained by either using a conically expanded reactor top section as shown in Figs. 3 to 6, or alternatively, arranging a sidestream drawoff for a portion of the reactant flow after the fluidized-bed section, whereby the reactor must be provided with a flow redistributor.
  • a fixed-bed reactor 76 is adapted above the fluidized-bed reactor tube 75 operated with recycling, both beds being arranged into a single contiguous reaction space. Liquid flow into the fixed bed is limited by diverting at least a portion of the reaction mixture exiting the fluidized bed to a recycling loop, where the mixture is cooled when necessary prior to pumping it to the reactor inlet nozzle. Above the sidestream drawoff is arranged a tabular heat exchanger 77, and further above this, a flow distributor 78. Also the entry side of the fluidized bed is provided with a flow distributor 78.
  • the arrangement provides easy recharging and discharging of particulate matter from the fluidized bed as the fluidized particles behave like a fluid. Consequently, catalyst recharging and discharging can be implemented using an arrangement illustrated in Fig. 8 for example.
  • Fig. 8 shows a system which facilitates run-time catalyst change during manufacture of tertiary ethers.
  • the apparatus comprises a reactor 81 incorporating a feed pump 82 and heat exchangers 83 and 84, the latter of which adapted to the recycle loop.
  • the catalyst acts as a flowing liquid, whereby it can be discharged from the reactor 81 simply by opening the nozzle 85 which is located below the upper surface of the fluidized bed.
  • a fluidized-bed reactor is rarely discharged fully, but rather, a seeding bed is left in the reactor.
  • the discharge point is located as close to the reactor flow distributor 86 as possible, since such an arrangement assures the discharge of large particles probably concentrated there.
  • the amount of discharged catalyst must be controllable. In the simplest manner this takes place with the help of a discharge container 87 that acts as a restriction for the catalyst charge limiter pipe which is routed to the interior of the discharge container, whereby the maximum charge is limited to the lower end of said limiter pipe.
  • the size of the discharge container is determined by the volume of desired discharge fraction of the catalyst charge; however, the container volume may not exceed the total volume of the catalyst contained in the reactor in fixed-bed form.
  • the discharge container 87 is placed either level with the reactor catalyst discharge nozzle 85 or below it.
  • the discharge procedure is as follows:
  • the container 87 is empty and purged with nitrogen.
  • the pipeline 88 to the top of the reactor 81 is filled with the liquid. All valves of the container are closed.
  • the container 87 is filled with the liquid recycled through the reactor by opening the valve 89.
  • the container pressure is kept above the vapour pressure of the liquid with the help of a pressostat 90 that controls a valve 91.
  • the reactor is filled with caution.
  • valves 95 and 96 are opened, whereby the catalyst can flow into the container. If the valves are kept open sufficiently long (1 to 2 min), the container is filled up to the level of the limiter pipe with the catalyst and the liquid. The correct transfer sequence is assured by level sensors.
  • valve 91 is opened to allow the container pressure fall below the vapour pressure of the liquid, whereby the liquid is evaporated away.
  • the container must have a heating jacket to prevent excessive cooling. If the volatile hydrocarbons are not collected using a recovery system, but rather, are routed to the flare for combustion, the valves 91 and 94 can be combined.
  • valve 97 is opened, whereby nitrogen is purged through the catalyst bed, thus evaporating any hydrocarbon residues (during a few hours typically).
  • the valve 98 is opened, whereby the spent catalyst falls into, e.g., a bin for transport away.
  • the procedure can be repeated from the beginning. Recharging of the reactor with catalyst is easy. Catalyst recharging in batches can be performed with the help of a feed container 99 located above the upper surface of the reactor catalyst bed (the minimum requirement being that the container bottom is located above the reactor flow distributor 86).
  • the volume of the container 99 is designed according to the desired maximum recharge batch. The maximum size of the container may not exceed the catalyst volume in the reactor in fixed-bed form.
  • the recharge procedure is as follows:
  • the container 99 is empty and purged with nitrogen. All valves of the container are closed.
  • the container is filled with the catalyst via the manhole.
  • the container 99 is purged with nitrogen via an inlet valve 100, while an outlet valve 101 is simultaneously held open to allow the nitrogen to escape from the container.
  • the container 99 is filled with the liquid recycled through the reactor 81 by opening the valve 103.
  • the container pressure is kept above the vapour pressure of the liquid with the help of a pressure control valve 104, which controls the valve 105.
  • the reactor is filled with caution.
  • valves 107 and 108 are opened, whereby the catalyst can flow into the reactor.
  • the container and the recharge pipe are flushed with the liquid via the valve 106.
  • the correct transfer sequence is assured by level sensors.
  • the valves 107 and 108 are closed.
  • the container is now filled with the liquid.
  • the container can be dumped into the reactor with the help of nitrogen pressure if nitrogen is available at sufficient pressure. If not, the container contents can be purged to the flare for combustion.
  • the apparatus employed was a reactor tube in which the methanol was reacted with the isoolefin mixture in a conventional fluidized bed.
  • the reactor was provided with recycling of the products.
  • Catalyst quantity 66 1 (not in fluidized state)
  • TAME in a combination fluidized/fixed-bed reactor tube
  • TAME was produced using equipment in which the apparatus employed in Example 1 was complemented with a heat exchanger (once-through-type on the hydrocarbon side), and above that, a 4500 mm high pipe of 154.1 mm ID with a perforated plate-type flow distributor 'placed at the lower section of the pipe.
  • the volume of catalyst fraction in this pipe section during normal operation is maintained at 70 1.
  • the reaction mixture was cooled to 50 °C by the heat exchanger.
  • the recycling sidestream is drawn off from below the heat exchanger.
  • the other reaction conditions were kept the same as in Example 1.
  • the obtained conversion of isoamylene (into TAME) was 60.7 %.
  • the reactor employed in the example had a fixed bed arranged above the fluidized bed with the help of a 30 % expansion section adapted in the reactor, whereby said expansion section accomplished the reduction of the liquid mixture superficial velocity below the minimum fluidization velocity. A portion of the product flow was recycled back to the inlet nozzle of initial reactants.
  • Feedstock composition :
  • Example 3 The apparatus and the reactant mixture were the same as in Example 3 with the exception that the fluidized-bed section was provided at 15000 mm height level from the flow distributor with a 3000-mm long heat exchanger comprising 1160 pcs. of OD 3 ⁇ 4 " heat exchanger tubes (cf. Fig. 5). With the help of the heat exchanger, the reaction mixture otherwise identical to that used in Example 3 was cooled to 50 °C.
  • the apparatus and reaction mixture were the same as in Example 4 with the exception that the bottom part of the upper conical section was provided with a flow redistributor and the sidestream drawoff was adapted to the reactor below said distributor (cf. Fig. 6).
  • Hydrocarbon feedstock Ethanol feedstock
  • the total feed rate to the reactor was 30 t/h and the feedstock temperature was 50 °C. In these conditions the conversion of isobutene into ETBE was 76.9 % .

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)

Abstract

La présente invention concerne un procédé et un appareil pour produire des éthers alkyles tertiaires à partir d'isooléfines et d'alcools. Selon le procédé, les isooléfines et les alcools sont mis en réaction les uns avec les autres dans une enceinte de réacteur (31) en présence d'une résine échangeuse de cations, pour former des éthers. Le procédé est effectué dans une cuve de réacteur comprenant une partie inférieure dans laquelle une section à lit fluidisé (35) peut être formée, et une partie supérieure dans laquelle une section à lit fixe (36) peut être formée. La buse d'entrée (30A) pour l'alimentation en mélange réactant s'adapte sur la partie inférieure de la cuve du réacteur et la buse de sortie (30B) pour l'évacuation des produits de la réaction s'adapte sur la partie supérieure de la cuve du réacteur. Selon l'invention, le lit de réaction fixe (36) est obtenue avantageusement en utilisant un réacteur équipé avec une zone d'expansion (37) au-dessus de laquelle la surface de la section transversale du réacteur est suffisamment augmentée pour réduire la vitesse superficielle du flux supérieur du réacteur depuis la partie inférieure du réacteur jusqu'à la partie supérieure, en dessous de la vitesse mini de fluidisation. Selon l'invention le catalyseur contenu dans le lit fixe peut être changé, même pendant le fonctionnement en réduisant temporairement la vitesse superficielle du liquide pour permettre aux particules de catalyseur contenues dans le bain fixe de tomber par gravité dans la partie inférieure dans laquelle le catalyseur utilisé peut être déchargé et remplacé par un nouveau catalyseur.
PCT/FI1993/000266 1992-06-22 1993-06-22 Procede et appareil pour produire des ethers tertiaires WO1994000411A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU43294/93A AU4329493A (en) 1992-06-22 1993-06-22 Process and apparatus for producing tertiary ethers

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI922909A FI93207C (fi) 1992-06-22 1992-06-22 Menetelmä ja laitteisto tertiaaristen eetterien valmistamiseksi
FI922909 1992-06-22

Publications (1)

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WO1994000411A1 true WO1994000411A1 (fr) 1994-01-06

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WO (1) WO1994000411A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1000919A1 (fr) * 1998-11-11 2000-05-17 Basf Aktiengesellschaft Procédé pour la préparation de butènes substitués
WO2012119260A1 (fr) 2011-03-10 2012-09-13 Ostara Nutrient Recovery Technologies Inc. Réacteur de précipitation de solutés contenus dans des eaux usées et méthodes associées

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3965039A (en) * 1974-11-19 1976-06-22 Chaplits Donat N Ion-exchange molded catalyst and method of its preparation
DE2944914A1 (de) * 1978-11-08 1980-05-22 Inst Francais Du Petrol Verfahren zur herstellung von aethern durch umsetzung von olefinen mit alkoholen
DD150697A1 (de) * 1980-04-16 1981-09-16 Roland Buettner Einrichtung zur erzeugung von stabilisierten wirbelschichten
US4589927A (en) * 1984-05-29 1986-05-20 Battelle Development Corporation Liquid multisolid fluidized bed processing

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3965039A (en) * 1974-11-19 1976-06-22 Chaplits Donat N Ion-exchange molded catalyst and method of its preparation
DE2944914A1 (de) * 1978-11-08 1980-05-22 Inst Francais Du Petrol Verfahren zur herstellung von aethern durch umsetzung von olefinen mit alkoholen
DD150697A1 (de) * 1980-04-16 1981-09-16 Roland Buettner Einrichtung zur erzeugung von stabilisierten wirbelschichten
US4589927A (en) * 1984-05-29 1986-05-20 Battelle Development Corporation Liquid multisolid fluidized bed processing

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1000919A1 (fr) * 1998-11-11 2000-05-17 Basf Aktiengesellschaft Procédé pour la préparation de butènes substitués
US6329555B1 (en) 1998-11-11 2001-12-11 Basf Aktiengesellschaft Preparation of substituted butenes
WO2012119260A1 (fr) 2011-03-10 2012-09-13 Ostara Nutrient Recovery Technologies Inc. Réacteur de précipitation de solutés contenus dans des eaux usées et méthodes associées
EP2683659A1 (fr) * 2011-03-10 2014-01-15 Ostara Nutrient Recovery Technologies Inc. Réacteur de précipitation de solutés contenus dans des eaux usées et méthodes associées
EP2683659A4 (fr) * 2011-03-10 2015-01-07 Ostara Nutrient Recovery Technologies Inc Réacteur de précipitation de solutés contenus dans des eaux usées et méthodes associées
US10266433B2 (en) 2011-03-10 2019-04-23 Ostara Nutrient Recovery Technologies Inc. Reactor for precipitating solutes from wastewater and associated methods

Also Published As

Publication number Publication date
FI922909A (fi) 1993-12-23
FI93207B (fi) 1994-11-30
FI93207C (fi) 1995-03-10
FI922909A0 (fi) 1992-06-22
AU4329493A (en) 1994-01-24

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