WO2016151508A1 - Method and apparatus for the production of diaryl carbonate - Google Patents

Method and apparatus for the production of diaryl carbonate Download PDF

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Publication number
WO2016151508A1
WO2016151508A1 PCT/IB2016/051644 IB2016051644W WO2016151508A1 WO 2016151508 A1 WO2016151508 A1 WO 2016151508A1 IB 2016051644 W IB2016051644 W IB 2016051644W WO 2016151508 A1 WO2016151508 A1 WO 2016151508A1
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Prior art keywords
carbonate
distillation column
alkyl alcohol
stream
alcohol
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PCT/IB2016/051644
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French (fr)
Inventor
Ignacio Vic Fernandez
Sergio Ferrer NADAL
Aaron David Bojarski
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Sabic Global Technologies B.V.
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Application filed by Sabic Global Technologies B.V. filed Critical Sabic Global Technologies B.V.
Priority to KR1020177026703A priority Critical patent/KR102021812B1/en
Priority to CN201680016660.6A priority patent/CN107406364A/en
Publication of WO2016151508A1 publication Critical patent/WO2016151508A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/08—Purification; Separation; Stabilisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
    • C07C69/96—Esters of carbonic or haloformic acids

Definitions

  • the present disclosure relates generally to a method and an apparatus for the production of diaryl carbonate. More particularly, the application is directed to a method and an apparatus for the production of diphenyl carbonate (“DPC").
  • DPC diphenyl carbonate
  • Polycarbonates are useful materials valued for their physical and optical properties.
  • Diaryl carbonates such as DPC
  • DPC are an important reactant in the production of polycarbonates.
  • polycarbonates can be manufactured by reacting Bisphenol A with DPC.
  • phosgene Early processes for the production of diaryl carbonates utilized phosgene as a reactant. The toxicity of phosgene, however, prompted the development of a non-phosgene process based on the production of an intermediate dialkyl carbonate.
  • diaryl carbonate typically involves a two-step process.
  • a dialkyl carbonate reacts with an aromatic alcohol to produce an alkyl aryl carbonate, e.g., phenyl methyl carbonate, and an alkyl alcohol (alkanol), such as methanol, in the presence of a transesterification catalyst (FIG. 1).
  • alkyl aryl carbonate e.g., phenyl methyl carbonate
  • alkyl alcohol alkanol
  • two molecules of the alkyl aryl carbonate undergo a disproportionation reaction to produce one molecule of diaryl carbonate, such as DPC, and one molecule of dialkyl carbonate, such as DMC.
  • TTP titanium tetra phenoxide
  • TTP is not commercially available, it can be produced in-situ from outsourced titanium tetra isopropoxide (TPT). Specifically, the synthesis of TTP from TPT is based on the reaction depicted in FIG. 3, in which TPT and phenol react to produce TTP and isopropyl alcohol (IP A). Employing TPT as the precursor catalyst may in principle lead to better handling conditions given TPT's comparatively lower melting point and liquid state at room temperature. TPT, however, has the drawback of contaminating product streams via formation of isopropyl alcohol (IP A). IPA may reach the DMC reactors in the plant due to plant topology and operation conditions (e.g., the destinations of methanol and DMC produced in the DPC plant), and IPA can compromise the amount and purity of DMC and consequently the DPC.
  • IP A isopropyl alcohol
  • the present disclosure provides a method for producing diaryl carbonate.
  • the method includes a step of reacting dialkyl carbonate, aromatic alcohol and a catalyst precursor in a first distillation column to give rise to diaryl carbonate.
  • the method includes a step for reacting, in the first distillation column, the aromatic alcohol with the catalyst precursor to produce a catalyst.
  • the method also includes a step of recovering from the first distillation column a first top stream that comprises an alkyl alcohol evolved in the first distillation column.
  • the method may also include a step of sending the first top stream to a second distillation column.
  • the method may further include recovering from the second distillation column a second stream that comprises at least some of the alkyl alcohol and an azeotrope.
  • the method further suitably includes a step of separating the alkyl alcohol from the azeotrope in the second stream.
  • the present disclosure provides a system for the production of diary 1 carbonate.
  • the system includes a first column including one or more inlets.
  • the one or more inlets receive one or more of a dialkyl carbonate, an aromatic alcohol and a catalyst precursor.
  • the distillation column also includes an outlet.
  • the one or more inlets communicate with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the catalyst precursor.
  • the outlet recovers a first top stream including alkyl alcohol from the first distillation column.
  • a second distillation column including an inlet and an outlet located downstream of the first distillation column. The inlet of the second distillation column is in fluid communication with the first top stream from the first distillation column.
  • the outlet of the second distillation column recovers a second stream including the alkyl alcohol and an azeotrope; the azeotrope may include a first alkyl alcohol (methanol) and a second alkyl alcohol (IP A).
  • a third distillation column including an inlet and a bottom outlet is located downstream of the second distillation column. The inlet of the third distillation column is in fluid communication with the second stream of the second distillation column. Moreover, the bottom outlet of the third distillation column recovers the alkyl alcohol.
  • FIG. 1 illustrates a transesterification reaction of dimethyl carbonate (DMC) and phenol to phenyl methyl carbonate PMC.
  • FIG. 2 illustrates a disproportionation reaction of PMC to diphenyl carbonate
  • FIG. 3 illustrates a synthesis reaction of titanium tetra phenoxide (TPT) from titanium isopropoxide (TTP) and phenol.
  • FIG. 4 illustrates an exemplary system for producing DPC according to an aspect of the application.
  • FIG. 5 illustrates an exemplary system for producing DPC according to another aspect of the application.
  • FIG. A more complete understanding of the components, processes, and apparatuses disclosed herein can be obtained by reference to the accompanying drawings.
  • FIG. These figures (also referred to herein as "FIG.") are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the embodiments.
  • specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure.
  • FIG. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.
  • Particularly desirable reactants useful on an industrial scale are DMC and phenol, which react to produce DPC. It is noted that these specific reactants will primarily be referred to below in the description for ease of reference and merely as non-limiting and exemplary materials.
  • FIGs Various feed, product, and recycle streams are disclosed in the FIGs. It will be appreciated by persons of ordinary skill in the art that the positioning of the various streams/lines as described herein as being, e.g., in the "top", “middle", “bottom” or “side” of a particular column is relative because the actual position at which material is to be introduced or recovered is dependent on the conditions being maintained in the particular column. For example, a stream entering the "bottom” of a column may actually enter several stages above the sump including the reboiler of the column, and a line/stream exiting the "top” of the column may actually exit several stages below the top stage including the condenser of the column. Thus, such terms herein are included for ease of reference to describe a general orientation regarding various columns and lines/streams and such terms are not meant to be limiting to one exact location.
  • the columns referred to herein can be interconnected by a series of feed/recycle lines which serve to transport streams comprising reactants and/or products.
  • the direction of flow in the FIGs. is indicated by an arrow.
  • Various valves, heaters, pumping equipment, instruments, filters, analyzers and other fittings can be included with the lines shown therein in adapting the design to a particular installation.
  • the FIGs. and their description may depict singular vessels, such as reaction vessels or mixing vessels, it is understood that multiple vessels in series or parallel may be used where suitable.
  • FIG. 4 illustrates a system 400 for producing diaryl carbonate according to an embodiment.
  • the system may either be run in batch or continuous mode.
  • the system 400 may also be run in bench or industrial scale.
  • the diaryl carbonate is diphenyl carbonate (DPC).
  • DPC is useful in PC synthesis, among other applications.
  • the recovered diaryl carbonate that is produced via the methods and systems of this application has less than about 1.0 wt% or even less than 0.5 wt% alkyl alcohol and/or its derivatives. In a preferred embodiment, the recovered diaryl carbonate has less than about 0.25 wt% alkyl alcohol and/or its derivatives present therein.
  • System 400 includes one or more input lines for introducing reactants. At least one of the input lines is for introducing an aromatic alcohol.
  • Aromatic alcohols may include but are not limited to an aromatic monohydroxy compound. The aromatic monohydroxy compound is not limited, so long as the hydroxyl group is directly bonded to the aromatic group: This compound may be represented by the general formula provided below (1).
  • Ar 1 represents an aromatic group having 5 to 30 carbon atoms.
  • aromatic monohydroxy compounds having such an Ar 1 include phenol; various alkylphenols such as cresol (isomers), xylenol (isomers), trimethylphenol (isomers), tetramethylphenol (isomers), ethylphenol (isomers), propylphenol (isomers), butylphenol (isomers), diethylphenol (isomers), methylethylphenol (isomers),
  • methylpropylphenol isomers
  • dipropylphenol isomers
  • methylbutylphenol isomers
  • pentylphenol isomers
  • hexylphenol isomers
  • cyclohexylphenol isomers
  • various alkoxyphenols such as methoxyphenol (isomers) and ethoxyphenol (isomers)
  • arylalkylphenols such as phenylpropylphenol (isomers); naphthol (isomers) and various substituted naphthols
  • heteroaromatic monohydroxy compounds such as hydroxypyridine (isomers), hydroxycoumarin (isomers) and hydroxy quinoline (isomers).
  • Those more preferably used in the application are unsubstituted phenol and substituted phenols in which Ar 1 is an aromatic group having 6 to 10 carbon atoms. Unsubstituted phenol is particularly preferable. Moreover, of these aromatic monohydroxy compounds, ones substantially not containing a halogen are preferably used in the present application.
  • the aromatic alcohol may include cresol, xylenol, phenol, trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, butylphenol, diethylphenol, methylethylphenol, methylpropylphenol, dipropylphenol, methylbutylphenol, pentylphenol, hexylphenol, cyclohexylphenol; methoxyphenol, ethoxyphenol,
  • phenol is introduced via line 10 in the system 400.
  • Phenol is also known as carbolic acid and has the molecular formula CeH 5 OH. Namely, the hydroxyl group is attached to an unsaturated aromatic, such as a benzene ring. Accordingly, phenols have greater acidity than typical alcohols due to stabilization of the conjugate base through resonance in the aromatic ring.
  • phenol from line 10 is mixed with phenol from recycle line (PhOH recycle) at a heat exchanger 12. The mixed phenol then enters column 210.
  • dialkyl carbonates generally include a carbonate group disposed between two alkyl groups. Examples include but are not limited to dimethyl carbonate, diethyl carbonate, dipropyl carbonate diallyl carbonate, dibutenyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonyl carbonate, didecyl carbonate, dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate, di(phenylpropyl) carbonate, di(phenylbutyl) carbonate, di(chlorobenzyl) carbonate, di(methoxybenzyl) carbonate, di(methoxymethyl) carbonate, di(methoxyethyl) carbon
  • DMC is introduced via line 30 in the system 400.
  • DMC from recycle line 120 is mixed with DMC from line 30 at a heat exchanger 32.
  • the mixed DMC then enters column 210.
  • a dialkyl carbonate used in the present invention is a compound represented by the general formula (2).
  • R 1 represents an alkyl group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aralkyl group having 6 to 10 carbon atoms.
  • R 1 examples include an alkyl group such as methyl, ethyl, propyl (isomers), allyl, butyl (isomers), butenyl (isomers), pentyl (isomers), hexyl (isomers), heptyl (isomers), octyl-(isomers), nonyl (isomers), decyl (isomers) and cyclohexylmethyl; an alicyclic group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl; and an aralkyl group such as benzyl, phenethyl (isomers), phenylpropyl (isomers), phenylbutyl (isomers) and methylbenzyl (isomers).
  • alkyl group such as methyl, ethyl, propyl (isomers), allyl, buty
  • alkyl groups, alicyclic group and aralkyl group may be substituted with other substituents such as lower alkyl group, a lower alkoxy group, a cyano group or a halogen atom, and may also contain an unsaturated bond therein.
  • dialkyl carbonates having such Rl include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (isomers), diallyl carbonate, dibutenyl carbonate (isomers), dibutyl carbonate (isomers), dipentyl carbonate (isomers), dihexyl carbonate (isomers), diheptyl carbonate (isomers), dioctyl carbonate (isomers), dinonyl carbonate (isomers), didecyl carbonate (isomers), dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (isomers), di(phenylpropyl) carbonate (isomers),
  • dialkyl carbonates ones preferably used in the application are dialkyl carbonates in which R 1 is an alkyl group having not more than four carbon atoms and not containing a halogen atom.
  • R 1 is an alkyl group having not more than four carbon atoms and not containing a halogen atom.
  • a particularly preferable one is dimethyl carbonate.
  • dialkyl carbonates particularly preferable ones are dialkyl carbonates produced in a state substantially not containing a halogen, for example ones produced from an alkylene carbonate substantially not containing a halogen and an alcohol substantially not containing a halogen.
  • the molar ratio of the dialkyl carbonate to the aromatic monohydroxy compound may be in a range of from 0.1 to 10. More preferably, the above molar ratio may be in range of from 0.5 to 5, and more preferably from 0.5 to 3. Outside this range, the amount of unreacted material remaining relative to the desired amount of alkyl aryl carbonate becomes high. This may not be efficient. Additionally, significantly more energy is required to recover this unreacted material.
  • column 210 can have a lower reaction section and an upper reaction section.
  • the chemical reaction may occur in the lower reaction section.
  • the reaction portion can be furnished with packing or fixed internals to provide at least 3 theoretical distillation stages otherwise known as trays.
  • the reaction section of column 210 may have greater than or equal to 10 trays. More preferably, column 210 may have between 10 and 60 trays. In another aspect, the column 210 may have between 15 and 40 distillation stages (trays).
  • Dump packing and/or arranged packing may also be used. Specifically, packings having a large surface area, good wetting and residence time of the liquid phase, such as, for example, Novalax rings, CY packings and others may be employed. Fixed internals, such as tray columns also can be employed, and specific examples include but are not limited to sieve trays, valve trays and bubble cap trays. One may also add soluble catalyst into a column or other unit having a bed of heterogeneous catalyst.
  • Another input line into the system may be for a catalyst.
  • catalysts include but are not limited to those capable of catalyzing the reactants entering the distillation column 210 for producing a diaryl carbonate.
  • the catalyst or the catalyst precursor can include but is not limited to iron, copper, nickel, cobalt, zinc, ruthenium, rhodium, palladium, silver, cadmium, rhenium, osmium, iridium, platinum, gold, mercury, zinc, tin, lead, and combinations comprising at least one of the foregoing metals, as well as organometallic complexes of the foregoing.
  • the catalyst may include titanium.
  • the catalyst may be titanium isopropoxide (TPT), titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide (TBT) and combination thereof. As shown in Table 1 below, TPT has improved handling characteristics over TTP.
  • the catalyst concentration should be sufficiently high to produce an acceptable yield, but is suitably below a concentration that would cause solid setting of the catalyst in the distillation column 210 or clogging of equipment.
  • the catalyst when homogenous, can be introduced to the reaction mixture in dissolved or suspended form together with the stream containing the aromatic alcohol. Alternatively, the catalyst can be introduced, for example, in the reaction alcohol or a suitable inert solvent. A heterogeneous catalyst can be used in a packed bed, a column, or in special distillation arrangements.
  • the catalyst enters the system through line 20.
  • a catalyst recycle can mix with fresh catalyst.
  • fresh catalyst may be a precursor catalyst, e.g., TPT.
  • the recycled catalyst may include TTP, TPT or combinations thereof.
  • the introduction of mixed catalyst into the reaction distillation column 210 is located downstream of the phenol input line 10.
  • mixed catalyst is introduced downstream of the heat exchanger 12, although catalyst may be introduced at other locations.
  • Precursor may also be selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide, and combinations thereof.
  • column 210 where phenol and DMC react in the presence of a catalyst may include a number of trays of various types.
  • a reboiler e.g., kettle- type reboiler
  • One may also use a condenser as needed.
  • the amount of catalyst used in the present invention varies depending upon the type of catalyst used, the types and proportions of the starting material compounds, and reaction conditions such as the reaction temperature and the reaction pressure.
  • the amount of the catalyst is generally in a range of about 0.0001 to 30% by weight, preferably from 0.005 to 10% by weight, and more preferably from 0.01 to 5% by weight, based on the total weight of the starting material.
  • the reaction between DMC and phenol in the presence of a catalyst can be performed, for example, at a temperature ranging from about 50°C to 250°C.
  • Distillation column 210 can be maintained at a pressure of 15 bar gauge (barg) to 35 barg, e.g., 1,500 kilopascal (kPa) to 3,500 kPa. Within this range, a pressure greater than or equal to 20 barg (2,000 kPa) can be employed. Also within this range, a pressure less than or equal to 28 barg (2,800 kPa) can be employed.
  • the reaction time for the transesterification reaction equates to the average residence time of the reaction liquid in the distillation column.
  • the reaction time varies depending on the form of the internal in the distillation column and the number of stages, the amount of the starting material fed into the column, the type and amount of the catalyst, the reaction conditions and other processing parameters.
  • the reaction time is generally in a range of from 0.01 to 10 hours, preferably from 0.05 to 5 hours, and more preferably from 0.1 to 3 hours.
  • the top of unit 210 may include the following products: an alkyl alcohol, DMC, methanol and an anisole.
  • line 40 leaving 210 may include Methanol:DMC:Anisole, as well as other lighter/heavier components. These by-products are submitted via line 40 which is split into separate lines 40a and 40b downstream by a separator 41.
  • Line 40a transports anisole, DMC and methanol.
  • Line 40a is fed to column 810, which may include stripping stages, a condenser and a reboiler.
  • the bottom product of 810 is rich in anisole and includes little phenol, DMC and methanol.
  • the bottom of 810 includes a line 42 to remove this product.
  • the top product of 810 is comparatively rich in DMC and includes little anisole, phenol and methanol.
  • the top product of 810 is recycled via line 130 to unit 410 to be combined with line 40b.
  • Line 40b includes alkyl alcohol, DMC and methanol and enters distillation column 410, either through the top or through a side .
  • the location of entry into the distillation column depends upon the concentration of the products in the respective streams entering the distillation column.
  • the distillation column may include a reboiler and a condenser. From the top of 410, a mixture of methanol and DMC is output via line 55. In one embodiment, the DMC and methanol mixture may be azeotropic.
  • a side draw line 60 exits 410.
  • the side draw line 60 includes alkyl alcohol, DMC and methanol.
  • the side draw line is connected to a column 420.
  • 420 is located downstream of 210 and 410. From 420, an azeotrope of DMC/methanol is obtained as a top product.
  • the top product exits through line 65 and is recycled to 410.
  • the top product including an azeotrope of DMC/methanol is combined with line 130 or combined with stream 55.
  • the bottom product of 420 includes a stream rich in alkyl alcohol and at least some DMC.
  • the stream exits 420 via line 70 and is subsequently discarded from the system 400.
  • the stream is sent on for incineration.
  • line 47 exiting 210 includes PMC, phenol, DMC, produced DPC, catalyst and other high-boiling products.
  • line 47 exiting 210 may include DMC:Phenol:PMC:DPC, with the remaining being heavy components and the catalyst.
  • Line 47 is introduced to distillation column 310.
  • 310 includes PMC, phenol, DPC, titanium catalyst and HBs.
  • 310 may be a rectification column. This column can carry out separation of materials based upon boiling point without driving a concurrent chemical reaction.
  • Outlet line 49a and input line 49b communicate with 410.
  • DMC may exit through line 49a or enter through line 49b of 310 between 410.
  • DMC may also be sent via a recycle line 120 in communication with lines 49a/b to a heat exchanger 32 whereby recycled DMC is mixed with fresh DMC 30 before moving to 210.
  • a recycle line 120 in communication with lines 49a/b to a heat exchanger 32 whereby recycled DMC is mixed with fresh DMC 30 before moving to 210.
  • the initial reaction between DMC and phenol in the presence of a catalyst takes place in 210.
  • Output line 48 includes DPC, PMC, phenol and titanium catalyst, including catalyst and/or precursor.
  • output line 48 from 310 may include
  • Outline line 48 communicates with reaction column 320.
  • the top product of 320 is phenol and leaves through line 100.
  • Line 100 is a phenol recycle line that is sent to heat exchanger 12 whereby recycled phenol is mixed with fresh phenol from line 10 prior to being sent to 210.
  • the bottom product of 320 includes PMC, DPC and catalyst. These products are sent via line 50 to a recovery unit 200 that may be described as a DPC/catalyst recovery unit. Recovery unit 200 includes an outlet 51 for PMC. The PMC is recycled to line 48 and subsequently sent back 320. The DPC is sent via line 150 to an outlet for final recovery or use in subsequent process. The catalyst may be sent via a recycle line back to 210. Preferably, the recycle line communicates with the fresh titanium line 20 before entering 210.
  • FIG. 5 A further embodiment is illustrated in FIG. 5. Similar structural elements and introductory reactants as discussed above with respect to FIG. 4 are employed.
  • an alkoxy titanate is introduced into the reaction distillation column 210 as a catalyst for the reaction of phenol and DMC.
  • line 60 includes an azeotrope of methanol and DMC and an alkyl alcohol.
  • Line 60 extends between 410 and 420.
  • 420 may include multiple stages and may operate with a reflux ratio equal to about 1 : 1, although other reflux ratios are suitable and may be set depending on the user's needs.
  • the bottom product stream includes alkyl alcohol and methanol which exits 420 via line 70.
  • the top product stream includes an azeotrope of methanol and DMC which exits vial line 65. The azeotrope may be recycled back to 410 or just recovered as product.
  • a method for producing a diaryl carbonate comprising: reacting dialkyl carbonate, aromatic alcohol and a catalyst precursor in a first distillation column to give rise to diaryl carbonate.
  • the method also includes reacting, in the first distillation column, the aromatic alcohol with the catalyst precursor to produce a catalyst.
  • the methods also include recovering from the first distillation column a first top stream that comprises an alkyl alcohol evolved in the first distillation column.
  • the methods also include sending the first top stream to a second distillation column and recovering from the second distillation column a second stream that comprises at least some of the alkyl alcohol and an azeotrope.
  • the methods may include separating at least some of the alkyl alcohol from the second stream.
  • the diaryl carbonate may comprise diphenyl carbonate.
  • the alkyl alcohol comprises isopropyl alcohol, butanol, methanol or combinations thereof.
  • the method includes a step of recovering a stream of the produced diaryl carbonate having less than about 0.5 wt.% alkyl alcohol present therein.
  • the produced diaryl carbonate has less than about 0.25 wt.% alkyl alcohol present therein, wherein the azeotrope comprises dialkyl carbonate and methanol.
  • Aspect 2 The method of aspect 1, wherein the reacting step involving the dialkyl carbonate, the aromatic alcohol and the catalyst precursor gives rise to an aryl alkyl carbonate.
  • Aspect 3 The method of aspect 2, further comprising reacting the aryl alkyl carbonate in the presence of the catalyst precursor to give rise to the diaryl carbonate.
  • Aspect 4 The method of any one of the preceding aspects, further comprising the step of sending the second stream to a third distillation column that operates at a reflux ratio of 1 :0.1 to 1 : 10 to separate the alcohol from the azeotrope.
  • Aspect 5 The method of aspect 4, wherein the azeotrope is communicated to a dialkyl carbonate production unit.
  • Aspect 6 The method of any of the preceding aspects, wherein the second stream is recovered via a side-draw from the second distillation column and communicated to a third distillation column.
  • Aspect 7 The method of any of the preceding aspects, wherein the second stream is recovered via the overhead of the second distillation column and communicated to a third distillation column.
  • Aspect 8 The method of any of the preceding aspects, wherein the recovery of the second stream via side -draw or overhead is selected according to an alkyl alcohol present in the second stream.
  • Aspect 9 the method of any of aspects 6 or 7, further comprising recycling the azeotrope recovered from the third distillation column to the second distillation column.
  • Aspect 10 The method of any of the preceding aspects, wherein the method gives rise to a product stream comprising dialkyl carbonate, said product stream comprising less than 1 wt% alkyl alcohol.
  • Aspect 11 The method of any of the preceding aspects, wherein the second stream is sent to a third distillation column, and wherein the third distillation operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
  • dialkyl carbonate is selected from dimethyl carbonate, diethyl carbonate, dipropyl carbonate diallyl carbonate, dibutenyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonyl carbonate, didecyl carbonate, dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate, di(phenylpropyl) carbonate, di(phenylbutyl) carbonate, di(chlorobenzyl) carbonate, di(methoxybenzyl) carbonate, di(methoxymethyl) carbonate, di(methoxyethyl) carbonate, di(chloroethyl) carbonate, di(cyanoethyl) carbonate,
  • Aspect 13 The method of any of the preceding aspects, wherein the aromatic alcohol is selected from cresol, xylenol, phenol, trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, butylphenol, diethylphenol, methylethylphenol, methylpropylphenol, dipropylphenol, methylbutylphenol, pentylphenol, hexylphenol, cyclohexylphenol;
  • Aspect 14 The method of any one of the preceding aspects, wherein the catalyst precursor is selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide and combinations thereof.
  • Aspect 15 The method of any one of the preceding aspects, further comprising: recovering a product stream comprising diaryl carbonate, the product stream having less than 0.5 wt.% alkyl alcohol present therein.
  • Aspect 16 The method of aspect 15, wherein the product stream has less than 0.25 wt.% alkyl alcohol present therein.
  • Aspect 17 The method of any of the preceding aspects, wherein the diaryl carbonate comprises diphenyl carbonate.
  • Aspect 18 The method of any one of the preced
  • Aspect 19 The method of any one of the preceding aspects, wherein the azeotrope comprises dialkyl carbonate and methanol.
  • Aspect 20 The method of any of the preceding aspects, wherein the azeotrope contains less than 1 wt% methanol.
  • Aspect 21 The method of aspect 1, wherein the azeotrope comprises less than 1 wt% alkyl alcohol.
  • Aspect 22 The method of aspect 1, wherein the azeotrope comprises less than 0.5 wt% alkyl alcohol.
  • a system for the production of diaryl carbonate comprising: a first distillation column including one or more inlets configured to receive one or more of a dialkyl carbonate, an aromatic alcohol and a catalyst precursor, and an outlet.
  • the one or more inlets are suitably in communication with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the catalyst precursor.
  • the outlet is suitably adapted to recover a first top stream from the first distillation column, the first top stream including an alkyl alcohol.
  • a system may also include a second distillation column located downstream of the first distillation column, the second distillation column including an inlet and an outlet, the inlet of the second distillation column being in fluid communication with the first top stream from the first distillation column, and the outlet being adapted to recover a second stream including the alkyl alcohol and an azeotrope.
  • Systems may further include a third distillation column located downstream of the second distillation column, the third distillation column including an inlet and a bottom outlet, the inlet of the third distillation column being in fluid communication with the second stream of the second distillation column, and the bottom outlet of the third distillation column being adapted to recover the alkyl alcohol.
  • Aspect 24 The system of aspect 23, wherein the outlet of the second distillation column is located on a sidewall thereof.
  • Aspect 25 The system of aspects 23 or 24, wherein the third distillation column includes about 25 stages and operates at a reflux ratio of from about 1 :0.1 to about 1 : 10.
  • Aspect 26 The system of any one of aspects 23-25, further comprising: a recycle line connecting an outlet of the third distillation column to an inlet of the second distillation column.
  • Aspect 27 The system of any one of aspects 23-26, further comprising: a separator located downstream of the second distillation column, the separator being configured to separate diaryl carbonate from a catalyst formed from the catalyst precursor.
  • Aspect 28 The system of any one of aspects 23-27, further comprising: a recycle line for catalyst, the recycle line placing the separator into fluid communication with an inlet of the first distillation column.
  • Aspect 29 The system of any one of aspects 23-28, wherein the system is configured to communicate the azeotrope to a dialkyl carbonate production unit.
  • Aspect 30 The system of aspect 24, wherein the system is capable of recovering the second stream through either of the sidewall outlet of the second distillation column or an overhead of the second distillation column.
  • Aspect 31 The system of any one of aspects 23-28, wherein the system is configured to give rise to an azeotrope that comprises less than 1 wt% alkyl alcohol.
  • Aspect 31 The system of any one of aspects 23-31, wherein the is third distillation column is configured to operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
  • a method for producing a diaryl carbonate comprising: reacting, in a first distillation column, a dialkyl carbonate and an aromatic alcohol in the presence of a titanium tetra alkyl oxide catalyst precursor so as to give rise to a product mixture comprising a diaryl carbonate, a titanium tetra phenoxide catalyst, and an alkyl alcohol corresponding to the alkyl of the catalyst precursor; and removing from the product mixture at least some of said alkyl alcohol, wherein at least some of the removing is effected by a second distillation column.
  • Aspect 33 The method of aspect 32, further comprising separating at least some of any dialkyl carbonate evolved in the first distillation column.
  • Aspect 34 The method of any of aspects 32-33, wherein the second distillation column is operated so as to give rise to a stream that comprises an azeotrope that comprises an alcohol and a dialkyl carbonate.
  • Aspect 35 The method of aspect 34, wherein the azeotrope is communicated to a third distillation column, the third distillation column being configured to separate the azeotrope from alkyl alcohol that is communicated to the further distillation unit.
  • Aspect 36 The method of aspect 32, wherein the alkyl alcohol is
  • Aspect 37 The method of aspect 32, wherein the alkyl alcohol is
  • Aspect 38 The method of aspect 36 or aspect 37, wherein the third distillation column operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
  • Aspect 39 The method of aspect 32, wherein the method gives rise to a product stream comprising dialkyl carbonate, said product stream comprising less than 1 wt% of the alkyl alcohol.
  • Aspect 40 The method of any of aspects 32-37 or 39, wherein the dialkyl carbonate comprises dimethyl carbonate or diethyl carbonate. Other suitable dialkyl carbonates are provided elsewhere herein.
  • Aspect 41 The method of any of aspects 32-37 or 39, wherein the aromatic alcohol comprises cresol, xylenol, phenol, or any combination thereof. Other suitable aromatic alcohols are provided elsewhere herein.
  • Aspect 42 The method of any of aspects 32-37 or 39, wherein the catalyst precursor is selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide and combinations thereof.
  • Aspect 43 The method of any of aspects 32-37 or 39, further comprising recovering a product stream comprising the diaryl carbonate, the product stream having less than 0.5 wt.% alkyl alcohol present therein.
  • Aspect 44 The method of aspect 43, wherein the product stream has less than 0.25 wt.% alkyl alcohol present therein.
  • Aspect 45 The method of aspect 35, wherein the third distillation column is operated to give rise to an azeotrope product stream that comprises less than 1 wt% alkyl alcohol.
  • a system for the production of diaryl carbonate comprising: a first reactive distillation column including one or more inlets configured to receive one or more of a dialkyl carbonate, an aromatic alcohol and a titanium tetra alkyl oxide catalyst precursor, and an outlet, the one or more inlets being in communication with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the titanium tetra alkyl oxide catalyst precursor, the outlet being adapted to recover a first top stream from the first distillation column, the first top stream including an alkyl alcohol, the reactive distillation column being configured to react dialkyl carbonate and aromatic alcohol in the presence of a titanium tetra alkyl oxide catalyst precursor so as to give rise to a product mixture comprising diaryl carbonate, a corresponding titanium tetra phenoxide catalyst and an alkyl alcohol corresponding to the alkyl of the catalyst precursor; a second distillation column located downstream of the first distillation column, the second distillation column including an inlet and an outlet,
  • Aspect 47 The system of aspect 46, further comprising: a recycle line connecting an outlet of the third distillation column to an inlet of the second distillation column.
  • Aspect 48 The system of any one of aspects 46-47, further comprising: a separator located downstream of the second distillation column, the separator being configured to separate diaryl carbonate from a catalyst formed from the catalyst precursor.
  • Aspect 49 The system of any one of aspects 46-47, further comprising: a recycle line for catalyst, the recycle line for catalyst placing the separator into fluid
  • Aspect 50 The system of any one of aspects 46-47, wherein the system is configured to recycle aromatic alcohol recovered in the system back to the first reactive distillation column.
  • Aspect 51 The system of any one of aspects 46-47, wherein the system is configured to give rise to an azeotrope product that comprises less than 1 wt% alkyl alcohol.

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Abstract

The present application describes a method for producing diaryl carbonate. The method includes a step of reacting dialkyl carbonate, aromatic alcohol and a catalyst precursor in a first distillation column to give rise to diaryl carbonate. The method includes a step for reacting, in the first distillation column, the aromatic alcohol with the catalyst precursor to produce a catalyst. The method also includes a step of recovering from the first distillation column a first top stream that comprises an alkyl alcohol evolved in the first distillation column. The present application also describes a system for the production of diaryl carbonate. The system includes a first distillation column including one or more inlets.

Description

METHOD AND APPARATUS FOR THE
PRODUCTION OF DIARYL CARBONATE
RELATED APPLICATION
[0001] The present application claims priority to and the benefit of European
Application No. 15382138.4, "Method And Apparatus For The Production Of Diaryl Carbonate" (filed March 23, 2015), the entirety of which application is incorporated here by reference for any and all purposes.
TECHNICAL FIELD
[0002] The present disclosure relates generally to a method and an apparatus for the production of diaryl carbonate. More particularly, the application is directed to a method and an apparatus for the production of diphenyl carbonate ("DPC").
BACKGROUND
[0003] Polycarbonates are useful materials valued for their physical and optical properties. Diaryl carbonates, such as DPC, are an important reactant in the production of polycarbonates. For example, polycarbonates can be manufactured by reacting Bisphenol A with DPC. Early processes for the production of diaryl carbonates utilized phosgene as a reactant. The toxicity of phosgene, however, prompted the development of a non-phosgene process based on the production of an intermediate dialkyl carbonate.
[0004] The production of diaryl carbonate typically involves a two-step process. In a first step, a dialkyl carbonate reacts with an aromatic alcohol to produce an alkyl aryl carbonate, e.g., phenyl methyl carbonate, and an alkyl alcohol (alkanol), such as methanol, in the presence of a transesterification catalyst (FIG. 1). Then, in a second step depicted in FIG. 2, two molecules of the alkyl aryl carbonate undergo a disproportionation reaction to produce one molecule of diaryl carbonate, such as DPC, and one molecule of dialkyl carbonate, such as DMC.
[0005] Although the reactions shown in FIG. 1 and FIG. 2 are the typical desired reactions, a number of side reactions occur, producing unwanted byproducts. These by-products can interfere with continuous production of the desired product, reduce the efficiency of the overall process, and in some cases even produce waste streams requiring special handling for disposal. This is the case for alkyl aryl ethers, such as anisole, which is a side product produced by the reaction of dialkyl carbonate and an aromatic alcohol.
[0006] The titanium tetra phenoxide (TTP) catalyst is used in the reactions depicted in FIG. 2. Handling of TTP:Phenol mixtures is troublesome because of the high melting point of TTP and its relatively low solubility in phenol. This in turn results in poor catalyst replacement and also to process line clogging and pump operating problems that lead to plant downtimes and loss of production.
[0007] Because TTP is not commercially available, it can be produced in-situ from outsourced titanium tetra isopropoxide (TPT). Specifically, the synthesis of TTP from TPT is based on the reaction depicted in FIG. 3, in which TPT and phenol react to produce TTP and isopropyl alcohol (IP A). Employing TPT as the precursor catalyst may in principle lead to better handling conditions given TPT's comparatively lower melting point and liquid state at room temperature. TPT, however, has the drawback of contaminating product streams via formation of isopropyl alcohol (IP A). IPA may reach the DMC reactors in the plant due to plant topology and operation conditions (e.g., the destinations of methanol and DMC produced in the DPC plant), and IPA can compromise the amount and purity of DMC and consequently the DPC.
[0008] Accordingly, there is a need in the art for a method and an apparatus for producing diaryl carbonate that provide for easy handling of reaction by-products.
[0009] There is also a need for a method and an apparatus for recovering diaryl carbonate having less contamination by alkyl alcohol.
SUMMARY
[0010] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to limit the scope of the claimed subject matter. The foregoing needs are met, to a great extent, by the present application directed to an apparatus, methods and systems for producing diaryl carbonate.
[0011] In one aspect, the present disclosure provides a method for producing diaryl carbonate. The method includes a step of reacting dialkyl carbonate, aromatic alcohol and a catalyst precursor in a first distillation column to give rise to diaryl carbonate. The method includes a step for reacting, in the first distillation column, the aromatic alcohol with the catalyst precursor to produce a catalyst. The method also includes a step of recovering from the first distillation column a first top stream that comprises an alkyl alcohol evolved in the first distillation column. The method may also include a step of sending the first top stream to a second distillation column. The method may further include recovering from the second distillation column a second stream that comprises at least some of the alkyl alcohol and an azeotrope. The method further suitably includes a step of separating the alkyl alcohol from the azeotrope in the second stream.
[0012] In another aspect, the present disclosure provides a system for the production of diary 1 carbonate. The system includes a first column including one or more inlets. The one or more inlets receive one or more of a dialkyl carbonate, an aromatic alcohol and a catalyst precursor. The distillation column also includes an outlet. The one or more inlets communicate with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the catalyst precursor. In an embodiment, the outlet recovers a first top stream including alkyl alcohol from the first distillation column. In another embodiment, a second distillation column including an inlet and an outlet located downstream of the first distillation column. The inlet of the second distillation column is in fluid communication with the first top stream from the first distillation column. The outlet of the second distillation column recovers a second stream including the alkyl alcohol and an azeotrope; the azeotrope may include a first alkyl alcohol (methanol) and a second alkyl alcohol (IP A). In yet another embodiment, a third distillation column including an inlet and a bottom outlet is located downstream of the second distillation column. The inlet of the third distillation column is in fluid communication with the second stream of the second distillation column. Moreover, the bottom outlet of the third distillation column recovers the alkyl alcohol.
[0013] There has thus been outlined, rather broadly, certain aspects of the application in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional aspects of the application that will be described below and which will form the subject matter of the claims appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to facilitate a more robust understanding of the application, reference is now made to the accompanying drawings, in which like elements are referenced with like numerals. These drawings should not be construed to limit the application and are intended only to be illustrative. [0015] FIG. 1 illustrates a transesterification reaction of dimethyl carbonate (DMC) and phenol to phenyl methyl carbonate PMC.
[0016] FIG. 2 illustrates a disproportionation reaction of PMC to diphenyl carbonate
(DPC).
[0017] FIG. 3 illustrates a synthesis reaction of titanium tetra phenoxide (TPT) from titanium isopropoxide (TTP) and phenol.
[0018] FIG. 4 illustrates an exemplary system for producing DPC according to an aspect of the application.
[0019] FIG. 5 illustrates an exemplary system for producing DPC according to another aspect of the application.
DETAILED DESCRIPTION
[0020] A detailed description of the illustrative aspects will be discussed in reference to various figures herein. Although this description provides detailed examples of possible implementations, it should be noted that the details are intended to be examples and thus do not limit the scope of the application.
[0021] A more complete understanding of the components, processes, and apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures (also referred to herein as "FIG.") are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the embodiments. Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.
[0022] Reference in this specification to "one aspect," "an aspect," "one or more aspects," or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one aspect of the disclosure. Moreover, the term "aspect" in various places in the specification is not necessarily referring to the same aspect. That is, various features are described which may be exhibited by some aspects and not by the other. Any ranges provided herein are inclusive of all intermediate values and are also combinable. [0023] The disclosure herein discusses new ways to improve the purity of the recovered product, improve the catalyst handling and hence the reliability of the plant, improve overall efficiency, reduce energy consumption and reduce the overall cost associated with the production of diaryl carbonate.
[0024] Particularly desirable reactants useful on an industrial scale are DMC and phenol, which react to produce DPC. It is noted that these specific reactants will primarily be referred to below in the description for ease of reference and merely as non-limiting and exemplary materials.
[0025] Various feed, product, and recycle streams are disclosed in the FIGs. It will be appreciated by persons of ordinary skill in the art that the positioning of the various streams/lines as described herein as being, e.g., in the "top", "middle", "bottom" or "side" of a particular column is relative because the actual position at which material is to be introduced or recovered is dependent on the conditions being maintained in the particular column. For example, a stream entering the "bottom" of a column may actually enter several stages above the sump including the reboiler of the column, and a line/stream exiting the "top" of the column may actually exit several stages below the top stage including the condenser of the column. Thus, such terms herein are included for ease of reference to describe a general orientation regarding various columns and lines/streams and such terms are not meant to be limiting to one exact location.
[0026] Also, the columns referred to herein can be interconnected by a series of feed/recycle lines which serve to transport streams comprising reactants and/or products. The direction of flow in the FIGs. is indicated by an arrow. Various valves, heaters, pumping equipment, instruments, filters, analyzers and other fittings, optionally, can be included with the lines shown therein in adapting the design to a particular installation. Also, although for illustrative purposes, the FIGs. and their description may depict singular vessels, such as reaction vessels or mixing vessels, it is understood that multiple vessels in series or parallel may be used where suitable.
[0027] FIG. 4 illustrates a system 400 for producing diaryl carbonate according to an embodiment. The system may either be run in batch or continuous mode. The system 400 may also be run in bench or industrial scale.
[0028] In a particular aspect, the diaryl carbonate is diphenyl carbonate (DPC). DPC is useful in PC synthesis, among other applications. In one embodiment, the recovered diaryl carbonate that is produced via the methods and systems of this application has less than about 1.0 wt% or even less than 0.5 wt% alkyl alcohol and/or its derivatives. In a preferred embodiment, the recovered diaryl carbonate has less than about 0.25 wt% alkyl alcohol and/or its derivatives present therein.
[0029] System 400 includes one or more input lines for introducing reactants. At least one of the input lines is for introducing an aromatic alcohol. Aromatic alcohols may include but are not limited to an aromatic monohydroxy compound. The aromatic monohydroxy compound is not limited, so long as the hydroxyl group is directly bonded to the aromatic group: This compound may be represented by the general formula provided below (1).
A^OH (1)
wherein Ar1 represents an aromatic group having 5 to 30 carbon atoms.
[0030] Examples of aromatic monohydroxy compounds having such an Ar1 include phenol; various alkylphenols such as cresol (isomers), xylenol (isomers), trimethylphenol (isomers), tetramethylphenol (isomers), ethylphenol (isomers), propylphenol (isomers), butylphenol (isomers), diethylphenol (isomers), methylethylphenol (isomers),
methylpropylphenol (isomers), dipropylphenol (isomers), methylbutylphenol (isomers), pentylphenol (isomers), hexylphenol (isomers) and cyclohexylphenol (isomers); various alkoxyphenols such as methoxyphenol (isomers) and ethoxyphenol (isomers); arylalkylphenols such as phenylpropylphenol (isomers); naphthol (isomers) and various substituted naphthols; and heteroaromatic monohydroxy compounds such as hydroxypyridine (isomers), hydroxycoumarin (isomers) and hydroxy quinoline (isomers). Those more preferably used in the application are unsubstituted phenol and substituted phenols in which Ar1 is an aromatic group having 6 to 10 carbon atoms. Unsubstituted phenol is particularly preferable. Moreover, of these aromatic monohydroxy compounds, ones substantially not containing a halogen are preferably used in the present application.
[0031] According to yet another embodiment, the aromatic alcohol may include cresol, xylenol, phenol, trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, butylphenol, diethylphenol, methylethylphenol, methylpropylphenol, dipropylphenol, methylbutylphenol, pentylphenol, hexylphenol, cyclohexylphenol; methoxyphenol, ethoxyphenol,
phenylpropylphenol, naphthol, o-Methyl salicylate and combinations thereof.
[0032] As depicted in FIG. 4, phenol is introduced via line 10 in the system 400. Phenol is also known as carbolic acid and has the molecular formula CeH5OH. Namely, the hydroxyl group is attached to an unsaturated aromatic, such as a benzene ring. Accordingly, phenols have greater acidity than typical alcohols due to stabilization of the conjugate base through resonance in the aromatic ring. Separately, phenol from line 10 is mixed with phenol from recycle line (PhOH recycle) at a heat exchanger 12. The mixed phenol then enters column 210.
[0033] Another input line may be used for introducing a dialkyl carbonate into the system 400. Examples of dialkyl carbonates generally include a carbonate group disposed between two alkyl groups. Examples include but are not limited to dimethyl carbonate, diethyl carbonate, dipropyl carbonate diallyl carbonate, dibutenyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonyl carbonate, didecyl carbonate, dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate, di(phenylpropyl) carbonate, di(phenylbutyl) carbonate, di(chlorobenzyl) carbonate, di(methoxybenzyl) carbonate, di(methoxymethyl) carbonate, di(methoxyethyl) carbonate, di(chloroethyl) carbonate, di(cyanoethyl) carbonate, and combinations thereof.
[0034] As depicted in FIG. 4, DMC is introduced via line 30 in the system 400.
Moreover, DMC from recycle line 120 is mixed with DMC from line 30 at a heat exchanger 32. The mixed DMC then enters column 210.
[0035] A dialkyl carbonate used in the present invention is a compound represented by the general formula (2).
R^OCOOR1 (2)
wherein R1 represents an alkyl group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aralkyl group having 6 to 10 carbon atoms.
[0036] Examples of R1 include an alkyl group such as methyl, ethyl, propyl (isomers), allyl, butyl (isomers), butenyl (isomers), pentyl (isomers), hexyl (isomers), heptyl (isomers), octyl-(isomers), nonyl (isomers), decyl (isomers) and cyclohexylmethyl; an alicyclic group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl; and an aralkyl group such as benzyl, phenethyl (isomers), phenylpropyl (isomers), phenylbutyl (isomers) and methylbenzyl (isomers). The above-mentioned alkyl groups, alicyclic group and aralkyl group may be substituted with other substituents such as lower alkyl group, a lower alkoxy group, a cyano group or a halogen atom, and may also contain an unsaturated bond therein.
[0037] Examples of dialkyl carbonates having such Rl include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (isomers), diallyl carbonate, dibutenyl carbonate (isomers), dibutyl carbonate (isomers), dipentyl carbonate (isomers), dihexyl carbonate (isomers), diheptyl carbonate (isomers), dioctyl carbonate (isomers), dinonyl carbonate (isomers), didecyl carbonate (isomers), dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (isomers), di(phenylpropyl) carbonate (isomers),
di(phenylbutyl) carbonate (isomers), di(chlorobenzyl) carbonate (isomers), di(methoxybenzyl) carbonate (isomers), di(methoxymethyl) carbonate, di(methoxyethyl) carbonate (isomers), di(chloroethyl) carbonate (isomers) and di(cyanoethyl) carbonate (isomers).
[0038] Of these dialkyl carbonates, ones preferably used in the application are dialkyl carbonates in which R1 is an alkyl group having not more than four carbon atoms and not containing a halogen atom. A particularly preferable one is dimethyl carbonate. Moreover, of preferable dialkyl carbonates, particularly preferable ones are dialkyl carbonates produced in a state substantially not containing a halogen, for example ones produced from an alkylene carbonate substantially not containing a halogen and an alcohol substantially not containing a halogen.
[0039] The molar ratio of the dialkyl carbonate to the aromatic monohydroxy compound may be in a range of from 0.1 to 10. More preferably, the above molar ratio may be in range of from 0.5 to 5, and more preferably from 0.5 to 3. Outside this range, the amount of unreacted material remaining relative to the desired amount of alkyl aryl carbonate becomes high. This may not be efficient. Additionally, significantly more energy is required to recover this unreacted material.
[0040] In one aspect of the application, column 210 can have a lower reaction section and an upper reaction section. The chemical reaction may occur in the lower reaction section. The reaction portion can be furnished with packing or fixed internals to provide at least 3 theoretical distillation stages otherwise known as trays. For instance, the reaction section of column 210 may have greater than or equal to 10 trays. More preferably, column 210 may have between 10 and 60 trays. In another aspect, the column 210 may have between 15 and 40 distillation stages (trays).
[0041] Dump packing and/or arranged packing may also be used. Specifically, packings having a large surface area, good wetting and residence time of the liquid phase, such as, for example, Novalax rings, CY packings and others may be employed. Fixed internals, such as tray columns also can be employed, and specific examples include but are not limited to sieve trays, valve trays and bubble cap trays. One may also add soluble catalyst into a column or other unit having a bed of heterogeneous catalyst.
[0042] Another input line into the system may be for a catalyst. Examples of catalysts include but are not limited to those capable of catalyzing the reactants entering the distillation column 210 for producing a diaryl carbonate. The catalyst or the catalyst precursor can include but is not limited to iron, copper, nickel, cobalt, zinc, ruthenium, rhodium, palladium, silver, cadmium, rhenium, osmium, iridium, platinum, gold, mercury, zinc, tin, lead, and combinations comprising at least one of the foregoing metals, as well as organometallic complexes of the foregoing. In particular, the catalyst may include titanium. More particularly, the catalyst may be titanium isopropoxide (TPT), titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide (TBT) and combination thereof. As shown in Table 1 below, TPT has improved handling characteristics over TTP.
Figure imgf000010_0001
[0043] The catalyst concentration should be sufficiently high to produce an acceptable yield, but is suitably below a concentration that would cause solid setting of the catalyst in the distillation column 210 or clogging of equipment. The catalyst, when homogenous, can be introduced to the reaction mixture in dissolved or suspended form together with the stream containing the aromatic alcohol. Alternatively, the catalyst can be introduced, for example, in the reaction alcohol or a suitable inert solvent. A heterogeneous catalyst can be used in a packed bed, a column, or in special distillation arrangements. [0044] As shown in FIG. 4, the catalyst enters the system through line 20. Moreover, a catalyst recycle can mix with fresh catalyst. As shown in FIG. 4, fresh catalyst may be a precursor catalyst, e.g., TPT. In one aspect, the recycled catalyst may include TTP, TPT or combinations thereof. In another aspect, the introduction of mixed catalyst into the reaction distillation column 210 is located downstream of the phenol input line 10. In an illustrative, non- limiting embodiment, mixed catalyst is introduced downstream of the heat exchanger 12, although catalyst may be introduced at other locations. Precursor may also be selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide, and combinations thereof.
[0045] In one exemplary embodiment, column 210 where phenol and DMC react in the presence of a catalyst may include a number of trays of various types. A reboiler (e.g., kettle- type reboiler) may be employed for hearing the column. One may also use a condenser as needed.
[0046] The amount of catalyst used in the present invention varies depending upon the type of catalyst used, the types and proportions of the starting material compounds, and reaction conditions such as the reaction temperature and the reaction pressure. The amount of the catalyst is generally in a range of about 0.0001 to 30% by weight, preferably from 0.005 to 10% by weight, and more preferably from 0.01 to 5% by weight, based on the total weight of the starting material.
[0047] In another aspect, the reaction between DMC and phenol in the presence of a catalyst can be performed, for example, at a temperature ranging from about 50°C to 250°C. Distillation column 210 can be maintained at a pressure of 15 bar gauge (barg) to 35 barg, e.g., 1,500 kilopascal (kPa) to 3,500 kPa. Within this range, a pressure greater than or equal to 20 barg (2,000 kPa) can be employed. Also within this range, a pressure less than or equal to 28 barg (2,800 kPa) can be employed.
[0048] In this application, according to yet another embodiment, the reaction time for the transesterification reaction equates to the average residence time of the reaction liquid in the distillation column. The reaction time varies depending on the form of the internal in the distillation column and the number of stages, the amount of the starting material fed into the column, the type and amount of the catalyst, the reaction conditions and other processing parameters. The reaction time is generally in a range of from 0.01 to 10 hours, preferably from 0.05 to 5 hours, and more preferably from 0.1 to 3 hours. [0049] The top of unit 210 may include the following products: an alkyl alcohol, DMC, methanol and an anisole. In one exemplary embodiment, line 40 leaving 210 may include Methanol:DMC:Anisole, as well as other lighter/heavier components. These by-products are submitted via line 40 which is split into separate lines 40a and 40b downstream by a separator 41.
[0050] Line 40a transports anisole, DMC and methanol. Line 40a is fed to column 810, which may include stripping stages, a condenser and a reboiler. The bottom product of 810 is rich in anisole and includes little phenol, DMC and methanol. The bottom of 810 includes a line 42 to remove this product. The top product of 810 is comparatively rich in DMC and includes little anisole, phenol and methanol. The top product of 810 is recycled via line 130 to unit 410 to be combined with line 40b.
[0051] Line 40b includes alkyl alcohol, DMC and methanol and enters distillation column 410, either through the top or through a side . As explained above, the location of entry into the distillation column depends upon the concentration of the products in the respective streams entering the distillation column.
[0052] The distillation column may include a reboiler and a condenser. From the top of 410, a mixture of methanol and DMC is output via line 55. In one embodiment, the DMC and methanol mixture may be azeotropic.
[0053] As depicted in FIG. 4 according to even another embodiment, a side draw line 60 exits 410. The side draw line 60 includes alkyl alcohol, DMC and methanol. The side draw line is connected to a column 420. 420 is located downstream of 210 and 410. From 420, an azeotrope of DMC/methanol is obtained as a top product. The top product exits through line 65 and is recycled to 410. In one aspect, the top product including an azeotrope of DMC/methanol is combined with line 130 or combined with stream 55. Meanwhile, the bottom product of 420 includes a stream rich in alkyl alcohol and at least some DMC. The stream exits 420 via line 70 and is subsequently discarded from the system 400. In one embodiment, the stream is sent on for incineration.
[0054] The bottom products exiting via line 47 from 210 will now be discussed in more detail below. Specifically, line 47 exiting 210 includes PMC, phenol, DMC, produced DPC, catalyst and other high-boiling products. In an embodiment, line 47 exiting 210 may include DMC:Phenol:PMC:DPC, with the remaining being heavy components and the catalyst. Line 47 is introduced to distillation column 310. Accordingly, 310 includes PMC, phenol, DPC, titanium catalyst and HBs. In one aspect 310 may be a rectification column. This column can carry out separation of materials based upon boiling point without driving a concurrent chemical reaction.
[0055] Outlet line 49a and input line 49b communicate with 410. DMC may exit through line 49a or enter through line 49b of 310 between 410. DMC may also be sent via a recycle line 120 in communication with lines 49a/b to a heat exchanger 32 whereby recycled DMC is mixed with fresh DMC 30 before moving to 210. As indicated above, the initial reaction between DMC and phenol in the presence of a catalyst takes place in 210.
[0056] Output line 48 includes DPC, PMC, phenol and titanium catalyst, including catalyst and/or precursor. In one embodiment, output line 48 from 310 may include
DMC:Phenol:PMC:DPC, with the remaining being heavy components and the catalyst. Outline line 48 communicates with reaction column 320. The top product of 320 is phenol and leaves through line 100. Line 100 is a phenol recycle line that is sent to heat exchanger 12 whereby recycled phenol is mixed with fresh phenol from line 10 prior to being sent to 210.
[0057] The bottom product of 320 includes PMC, DPC and catalyst. These products are sent via line 50 to a recovery unit 200 that may be described as a DPC/catalyst recovery unit. Recovery unit 200 includes an outlet 51 for PMC. The PMC is recycled to line 48 and subsequently sent back 320. The DPC is sent via line 150 to an outlet for final recovery or use in subsequent process. The catalyst may be sent via a recycle line back to 210. Preferably, the recycle line communicates with the fresh titanium line 20 before entering 210.
[0058] A further embodiment is illustrated in FIG. 5. Similar structural elements and introductory reactants as discussed above with respect to FIG. 4 are employed. In the system 500 of FIG. 5, an alkoxy titanate is introduced into the reaction distillation column 210 as a catalyst for the reaction of phenol and DMC.
[0059] By employing an alkoxy titanate, a side draw is not required from 410.
Accordingly line 55 is not illustrated in FIG. 5. Accordingly, line 60 includes an azeotrope of methanol and DMC and an alkyl alcohol. Line 60 extends between 410 and 420. 420 may include multiple stages and may operate with a reflux ratio equal to about 1 : 1, although other reflux ratios are suitable and may be set depending on the user's needs. The bottom product stream includes alkyl alcohol and methanol which exits 420 via line 70. The top product stream includes an azeotrope of methanol and DMC which exits vial line 65. The azeotrope may be recycled back to 410 or just recovered as product.
[0060] The following are illustrative examples and do not serve to limit the scope of the present disclosure or the appended claims. [0061] Example 1
[0062] 13183 kg/h of fresh phenol, 10274 kg/h of DMC and 25.5 kg/h of titanium butoxide are fed to a DPC production plant shown in FIG. 4. A reaction occurs in 210. The highest concentration of butanol is along the 410 column, which requires the use of a distillation column treating a purge stream. The side draw stream of 410 encompasses a stream mainly with DMC (93.5 wt% DMC, 5.0 wt% methanol and 1.5 wt% butanol). This stream is subject to separation via distillation in 420. The products of the new distillation column 420 are: top azeotrope methanol and DMC while the bottoms will contain a mixture of butanol and DMC. The bottoms stream which completely separates butanol is obtained mainly having a flow of 22 kg/h of butanol and 1172 kg of DMC. This example produces 14944 kg/h of high-quality DPC.
[0063] Example 2
[0064] 13025 kg/h of fresh phenol, 8293 kg/h of DMC and 20 kg/h of titanium isopropoxide are fed to a DPC production plant as described in FIG. 5. In this case, the highest concentration of isopropanol (IP A) is at the top of 410 top. 6,472 kg/h are distilled from 410 with a composition of (69.9 wt% methanol, 29.1 wt% DMC, 0.7 wt% C02 and 0.3 wt% isopropanol). This stream is sent to a new distillation column. The products of the new distillation column are: top an azeotrope of methanol and DMC while the bottoms will contain a mixture of IPA and methanol. In particular, the bottom stream contains 17 kg/h of isopropanol and 23 kg/h of methanol. The bottom product stream is purged and is incinerated. This plant produces 14925 kg/h of high-quality DPC.
[0065] While the methods and systems have been described in terms of what are presently considered to be specific aspects, the disclosure need not be limited to the disclosed aspects. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures. The present disclosure includes any and all aspects of the following claims.
[0066] Further Disclosure
[0067] Aspect 1. A method for producing a diaryl carbonate, comprising: reacting dialkyl carbonate, aromatic alcohol and a catalyst precursor in a first distillation column to give rise to diaryl carbonate. The method also includes reacting, in the first distillation column, the aromatic alcohol with the catalyst precursor to produce a catalyst. The methods also include recovering from the first distillation column a first top stream that comprises an alkyl alcohol evolved in the first distillation column. [0068] The methods also include sending the first top stream to a second distillation column and recovering from the second distillation column a second stream that comprises at least some of the alkyl alcohol and an azeotrope. The methods may include separating at least some of the alkyl alcohol from the second stream. The diaryl carbonate may comprise diphenyl carbonate. In some embodiments, the alkyl alcohol comprises isopropyl alcohol, butanol, methanol or combinations thereof.
[0069] In another embodiment, the method includes a step of recovering a stream of the produced diaryl carbonate having less than about 0.5 wt.% alkyl alcohol present therein. In an exemplary embodiment, the produced diaryl carbonate has less than about 0.25 wt.% alkyl alcohol present therein, wherein the azeotrope comprises dialkyl carbonate and methanol.
[0070] Aspect 2. The method of aspect 1, wherein the reacting step involving the dialkyl carbonate, the aromatic alcohol and the catalyst precursor gives rise to an aryl alkyl carbonate.
[0071] Aspect 3. The method of aspect 2, further comprising reacting the aryl alkyl carbonate in the presence of the catalyst precursor to give rise to the diaryl carbonate.
[0072] Aspect 4. The method of any one of the preceding aspects, further comprising the step of sending the second stream to a third distillation column that operates at a reflux ratio of 1 :0.1 to 1 : 10 to separate the alcohol from the azeotrope.
[0073] Aspect 5. The method of aspect 4, wherein the azeotrope is communicated to a dialkyl carbonate production unit.
[0074] Aspect 6. The method of any of the preceding aspects, wherein the second stream is recovered via a side-draw from the second distillation column and communicated to a third distillation column.
[0075] Aspect 7. The method of any of the preceding aspects, wherein the second stream is recovered via the overhead of the second distillation column and communicated to a third distillation column.
[0076] Aspect 8. The method of any of the preceding aspects, wherein the recovery of the second stream via side -draw or overhead is selected according to an alkyl alcohol present in the second stream.
[0077] Aspect 9, the method of any of aspects 6 or 7, further comprising recycling the azeotrope recovered from the third distillation column to the second distillation column. [0078] Aspect 10. The method of any of the preceding aspects, wherein the method gives rise to a product stream comprising dialkyl carbonate, said product stream comprising less than 1 wt% alkyl alcohol.
[0079] Aspect 11. The method of any of the preceding aspects, wherein the second stream is sent to a third distillation column, and wherein the third distillation operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
[0080] Aspect 12. The method of any of the preceding aspects, wherein the dialkyl carbonate is selected from dimethyl carbonate, diethyl carbonate, dipropyl carbonate diallyl carbonate, dibutenyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonyl carbonate, didecyl carbonate, dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate, di(phenylpropyl) carbonate, di(phenylbutyl) carbonate, di(chlorobenzyl) carbonate, di(methoxybenzyl) carbonate, di(methoxymethyl) carbonate, di(methoxyethyl) carbonate, di(chloroethyl) carbonate, di(cyanoethyl) carbonate, and combinations thereof.
[0081] Aspect 13. The method of any of the preceding aspects, wherein the aromatic alcohol is selected from cresol, xylenol, phenol, trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, butylphenol, diethylphenol, methylethylphenol, methylpropylphenol, dipropylphenol, methylbutylphenol, pentylphenol, hexylphenol, cyclohexylphenol;
methoxyphenol, ethoxyphenol, phenylpropylphenol, naphthol, o-Methyl salicylate and combinations thereof.
[0082] Aspect 14. The method of any one of the preceding aspects, wherein the catalyst precursor is selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide and combinations thereof.
[0083] Aspect 15. The method of any one of the preceding aspects, further comprising: recovering a product stream comprising diaryl carbonate, the product stream having less than 0.5 wt.% alkyl alcohol present therein.
[0084] Aspect 16. The method of aspect 15, wherein the product stream has less than 0.25 wt.% alkyl alcohol present therein.
[0085] Aspect 17. The method of any of the preceding aspects, wherein the diaryl carbonate comprises diphenyl carbonate.
[0086] Aspect 18. The method of any one of the preced|ing aspects, wherein the alkyl alcohol comprises isopropyl alcohol, butanol, methanol, or any combination thereof. [0087] Aspect 19. The method of any one of the preceding aspects, wherein the azeotrope comprises dialkyl carbonate and methanol.
[0088] Aspect 20. The method of any of the preceding aspects, wherein the azeotrope contains less than 1 wt% methanol.
[0089] Aspect 21. The method of aspect 1, wherein the azeotrope comprises less than 1 wt% alkyl alcohol.
[0090] Aspect 22. The method of aspect 1, wherein the azeotrope comprises less than 0.5 wt% alkyl alcohol.
[0091] Aspect 23. A system for the production of diaryl carbonate comprising: a first distillation column including one or more inlets configured to receive one or more of a dialkyl carbonate, an aromatic alcohol and a catalyst precursor, and an outlet. The one or more inlets are suitably in communication with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the catalyst precursor. The outlet is suitably adapted to recover a first top stream from the first distillation column, the first top stream including an alkyl alcohol.
[0092] A system may also include a second distillation column located downstream of the first distillation column, the second distillation column including an inlet and an outlet, the inlet of the second distillation column being in fluid communication with the first top stream from the first distillation column, and the outlet being adapted to recover a second stream including the alkyl alcohol and an azeotrope. Systems may further include a third distillation column located downstream of the second distillation column, the third distillation column including an inlet and a bottom outlet, the inlet of the third distillation column being in fluid communication with the second stream of the second distillation column, and the bottom outlet of the third distillation column being adapted to recover the alkyl alcohol.
[0093] Aspect 24. The system of aspect 23, wherein the outlet of the second distillation column is located on a sidewall thereof.
[0094] Aspect 25. The system of aspects 23 or 24, wherein the third distillation column includes about 25 stages and operates at a reflux ratio of from about 1 :0.1 to about 1 : 10.
[0095] Aspect 26. The system of any one of aspects 23-25, further comprising: a recycle line connecting an outlet of the third distillation column to an inlet of the second distillation column.
[0096] Aspect 27. The system of any one of aspects 23-26, further comprising: a separator located downstream of the second distillation column, the separator being configured to separate diaryl carbonate from a catalyst formed from the catalyst precursor. [0097] Aspect 28. The system of any one of aspects 23-27, further comprising: a recycle line for catalyst, the recycle line placing the separator into fluid communication with an inlet of the first distillation column.
[0098] Aspect 29. The system of any one of aspects 23-28, wherein the system is configured to communicate the azeotrope to a dialkyl carbonate production unit.
[0099] Aspect 30. The system of aspect 24, wherein the system is capable of recovering the second stream through either of the sidewall outlet of the second distillation column or an overhead of the second distillation column.
[00100] Aspect 31. The system of any one of aspects 23-28, wherein the system is configured to give rise to an azeotrope that comprises less than 1 wt% alkyl alcohol.
[00101] Aspect 31. The system of any one of aspects 23-31, wherein the is third distillation column is configured to operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
[00102] Aspect 32. A method for producing a diaryl carbonate, comprising: reacting, in a first distillation column, a dialkyl carbonate and an aromatic alcohol in the presence of a titanium tetra alkyl oxide catalyst precursor so as to give rise to a product mixture comprising a diaryl carbonate, a titanium tetra phenoxide catalyst, and an alkyl alcohol corresponding to the alkyl of the catalyst precursor; and removing from the product mixture at least some of said alkyl alcohol, wherein at least some of the removing is effected by a second distillation column.
[00103] Aspect 33. The method of aspect 32, further comprising separating at least some of any dialkyl carbonate evolved in the first distillation column.
[00104] Aspect 34. The method of any of aspects 32-33, wherein the second distillation column is operated so as to give rise to a stream that comprises an azeotrope that comprises an alcohol and a dialkyl carbonate.
[00105] Aspect 35. The method of aspect 34, wherein the azeotrope is communicated to a third distillation column, the third distillation column being configured to separate the azeotrope from alkyl alcohol that is communicated to the further distillation unit.
[00106] Aspect 36. The method of aspect 32, wherein the alkyl alcohol is
communicated to a third distillation column as an overhead product of the second distillation column.
[00107] Aspect 37. The method of aspect 32, wherein the alkyl alcohol is
communicated to a third distillation column as a side draw of the second distillation column. [00108] Aspect 38. The method of aspect 36 or aspect 37, wherein the third distillation column operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
[00109] Aspect 39. The method of aspect 32, wherein the method gives rise to a product stream comprising dialkyl carbonate, said product stream comprising less than 1 wt% of the alkyl alcohol.
[00110] Aspect 40. The method of any of aspects 32-37 or 39, wherein the dialkyl carbonate comprises dimethyl carbonate or diethyl carbonate. Other suitable dialkyl carbonates are provided elsewhere herein.
[00111] Aspect 41. The method of any of aspects 32-37 or 39, wherein the aromatic alcohol comprises cresol, xylenol, phenol, or any combination thereof. Other suitable aromatic alcohols are provided elsewhere herein.
[00112] Aspect 42. The method of any of aspects 32-37 or 39, wherein the catalyst precursor is selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide and combinations thereof.
[00113] Aspect 43. The method of any of aspects 32-37 or 39, further comprising recovering a product stream comprising the diaryl carbonate, the product stream having less than 0.5 wt.% alkyl alcohol present therein.
[00114] Aspect 44. The method of aspect 43, wherein the product stream has less than 0.25 wt.% alkyl alcohol present therein.
[00115] Aspect 45. The method of aspect 35, wherein the third distillation column is operated to give rise to an azeotrope product stream that comprises less than 1 wt% alkyl alcohol.
[00116] Aspect 46. A system for the production of diaryl carbonate comprising: a first reactive distillation column including one or more inlets configured to receive one or more of a dialkyl carbonate, an aromatic alcohol and a titanium tetra alkyl oxide catalyst precursor, and an outlet, the one or more inlets being in communication with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the titanium tetra alkyl oxide catalyst precursor, the outlet being adapted to recover a first top stream from the first distillation column, the first top stream including an alkyl alcohol, the reactive distillation column being configured to react dialkyl carbonate and aromatic alcohol in the presence of a titanium tetra alkyl oxide catalyst precursor so as to give rise to a product mixture comprising diaryl carbonate, a corresponding titanium tetra phenoxide catalyst and an alkyl alcohol corresponding to the alkyl of the catalyst precursor; a second distillation column located downstream of the first distillation column, the second distillation column including an inlet and an outlet, the inlet of the second distillation column being in fluid communication with the first top stream from the first distillation column, and the outlet of the second distillation column being adapted to recover a second stream including the alkyl alcohol; and a third distillation column located downstream of the second distillation column, the third distillation column including an inlet and a bottom outlet, the inlet of the third distillation column being in fluid communication with the second stream of the second distillation column, and the bottom outlet of the third distillation column being adapted to recover the alkyl alcohol.
[00117] Aspect 47. The system of aspect 46, further comprising: a recycle line connecting an outlet of the third distillation column to an inlet of the second distillation column.
[00118] Aspect 48. The system of any one of aspects 46-47, further comprising: a separator located downstream of the second distillation column, the separator being configured to separate diaryl carbonate from a catalyst formed from the catalyst precursor.
[00119] Aspect 49. The system of any one of aspects 46-47, further comprising: a recycle line for catalyst, the recycle line for catalyst placing the separator into fluid
communication with an inlet of the first distillation column.
[00120] Aspect 50. The system of any one of aspects 46-47, wherein the system is configured to recycle aromatic alcohol recovered in the system back to the first reactive distillation column.
[00121] Aspect 51. The system of any one of aspects 46-47, wherein the system is configured to give rise to an azeotrope product that comprises less than 1 wt% alkyl alcohol.

Claims

What is Claimed:
1. A method for producing a diaryl carbonate, comprising:
reacting, in a first distillation column, a dialkyl carbonate and an aromatic alcohol in the presence of a titanium tetra alkyl oxide catalyst precursor so as to give rise to a product mixture comprising a diaryl carbonate, a titanium tetra phenoxide catalyst, and an alkyl alcohol corresponding to the alkyl of the catalyst precursor; and
removing from the product mixture at least some of said alkyl alcohol, wherein at least some of the removing is effected by a second distillation column.
2. The method of claim 1, further comprising separating at least some of any dialkyl
carbonate evolved in the first distillation column.
3. The method of claim 1, wherein the second distillation column is operated so as to give rise to a stream that comprises an azeotrope that comprises an alcohol and a dialkyl carbonate.
4. The method of claim 3, wherein the azeotrope is communicated to a third distillation column, the third distillation column being configured to separate the azeotrope from alkyl alcohol that is communicated to the further distillation unit.
5. The method of claim 1, wherein the alkyl alcohol is communicated to a third distillation column as an overhead product of the second distillation column.
6. The method of claim 1, wherein the alkyl alcohol is communicated to a third distillation column as a side draw of the second distillation column.
7. The method of claim 5 or claim 6, wherein the third distillation column operates so as to give rise to a stream that comprises less than 1 wt% alkyl alcohol.
8. The method of claim 1, wherein the method gives rise to a product stream comprising dialkyl carbonate, said product stream comprising less than 1 wt% of the alkyl alcohol.
9. The method of any of claims 1-6 or 8, wherein the dialkyl carbonate is selected from dimethyl carbonate, diethyl carbonate, dipropyl carbonate diallyl carbonate, dibutenyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonyl carbonate, didecyl carbonate, dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate, di(phenylpropyl) carbonate, di(phenylbutyl) carbonate, di(chlorobenzyl) carbonate, di(methoxybenzyl) carbonate, di(methoxymethyl) carbonate, di(methoxyethyl) carbonate, di(chloroethyl) carbonate, di(cyanoethyl) carbonate, and combinations thereof.
10. The method of any of claims 1-6, or 8, wherein the aromatic alcohol is selected from cresol, xylenol, phenol, trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, butylphenol, diethylphenol, methylethylphenol, methylpropylphenol, dipropylphenol, methylbutylphenol, pentylphenol, hexylphenol, cyclohexylphenol; methoxyphenol, ethoxyphenol, phenylpropylphenol, naphthol, o-Methyl salicylate and combinations thereof.
11. The method of any of claims 1-6 or 8, wherein the catalyst precursor is selected from titanium isopropoxide, titanium tetrachloride, titanium isobutyl, titanium tetrabutoxide and combinations thereof.
12. The method of any of claims 1-6 or 8, further comprising recovering a product stream comprising the diaryl carbonate, the product stream having less than 0.5 wt.% alkyl alcohol present therein.
13. The method of claim 12, wherein the product stream has less than 0.25 wt.% alkyl
alcohol present therein.
14. The method of claim 4, wherein the third distillation column is operated to give rise to an azeotrope product stream that comprises less than 1 wt% alkyl alcohol.
15. A system for the production of diaryl carbonate comprising: a first reactive distillation column including one or more inlets configured to receive one or more of a dialkyl carbonate, an aromatic alcohol and a titanium tetra alkyl oxide catalyst precursor, and an outlet,
the one or more inlets being in communication with one or more input lines for one or more of dialkyl carbonate, the aromatic alcohol and the titanium tetra alkyl oxide catalyst precursor,
the outlet being adapted to recover a first top stream from the first distillation column, the first top stream including an alkyl alcohol,
the reactive distillation column being configured to react dialkyl carbonate and aromatic alcohol in the presence of a titanium tetra alkyl oxide catalyst precursor so as to give rise to a product mixture comprising diaryl carbonate, a corresponding titanium tetra phenoxide catalyst and an alkyl alcohol corresponding to the alkyl of the catalyst precursor;
a second distillation column located downstream of the first distillation column, the second distillation column including an inlet and an outlet, the inlet of the second distillation column being in fluid communication with the first top stream from the first distillation column, and
the outlet of the second distillation column being adapted to recover a second stream including the alkyl alcohol; and
a third distillation column located downstream of the second distillation column, the third distillation column including an inlet and a bottom outlet, the inlet of the third distillation column being in fluid communication with the second stream of the second distillation column, and
the bottom outlet of the third distillation column being adapted to recover the alkyl alcohol.
16. The system of claim 15, further comprising: a recycle line connecting an outlet of the third distillation column to an inlet of the second distillation column.
17. The system of any one of claims 15-16, further comprising: a separator located downstream of the second distillation column, the separator being configured to separate diaryl carbonate from a catalyst formed from the catalyst precursor.
18. The system of any one of claims 15-16, further comprising:
a recycle line for catalyst, the recycle line for catalyst placing the separator into fluid communication with an inlet of the first distillation column.
19. The system of any one of claims 15-16, wherein the system is configured to recycle aromatic alcohol recovered in the system back to the first reactive distillation column.
20. The system of any one of claims 15-16, wherein the system is configured to give rise to an azeotrope product that comprises less than 1 wt% alkyl alcohol.
PCT/IB2016/051644 2015-03-23 2016-03-23 Method and apparatus for the production of diaryl carbonate WO2016151508A1 (en)

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