Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
  • C07C37/11—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions increasing the number of carbon atoms
  • C07C37/20—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions increasing the number of carbon atoms using aldehydes or ketones
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
  • C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
  • C07C37/70—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment
  • C07C37/84—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment by crystallisation

Definitions

• the present invention relates to a process for producing bisphenol A, a raw material for producing plastics, in particular polycarbonates.
• Bisphenol A 2,2-bis-(4-hydroxyphenyl)propane, named also the p,p'-BPA isomer
• BPA Bisphenol A
• p,p'-BPA isomer is used for producing plastics, in particular polycarbonates, their blends and epoxy resins, as well as, but in minor quantities, for producing phenoplasts, unsaturated polyester resins, polysulfones, polyetherimide and polyacrylic resins as well as polyuretanes and additions for plastics, inter alia fiameretardants, for example tetrabromobisphenol A and phenylphosphates of BPA and thermal stabilizers for polyvinyl chloride.
• fiameretardants for example tetrabromobisphenol A and phenylphosphates of BPA and thermal stabilizers for polyvinyl chloride.
• An alternative process for catalyzing the reaction of obtaining BPA is the use of strongly acidic ion-exchange resins (cation exchangers) which met larger and larger approbation, and finally displaced methods using H 2 SO 4 or HCl as catalysts for condensation reactions. It was recommended also the use of sulfonated copolymers of styrene and divinylbenzene (DVB) and sulfonated phenol-formaldehyde resins, the first of the mentioned catalyst types being broadly used at present on an industrial scale. Initially, cation exchangers of considerable cross-linking degree were used, and next, gel cation exchangers of lower cross-linking degree were started to be used (2-4 cg/g ofDVB).
• promoters which are thioorganic compounds having a thiol group or being capable of its formation in condensation reaction conditions. Numerous tests for using homogeneous promoters were taken up. However, their use caused problems associated with obtaining a product of high quality. For this reason, at present, more and more popular are ion-exchange resins modified with thioorganic compounds in such a manner which provides their attachment with a sulfonic group, and to this end amine groups or heterocyclic compounds comprising nitrogen atom(s) of basic character are used mostly.
• One embodiment used for a synthesis unit includes a multi-stage system of flow reactors with a fixed-bed catalyst, connected in series through heat exchangers which enable to maintain an assumed temperature range in successive reactors, individual embodiments differing each other in supplying acetone and post-crystallization liquors resulted from successive stages of the BPA isolation and purification, hi the case of such embodiments for a reaction system, are known and described inter alia in the US-Patent 6414199 advantages resulting from dividing the stream of acetone to be supplied into reactors connected in series, which advantages consist, first of all, in increasing the catalyst lifetime and selectivity of a condensation reaction, which results from a better temperature distribution in the catalyst bed as well as from more possibilities of controlling the course of a BPA synthesis reaction.
• Advantages are known which result from recycling post-crystallization liquors, and in the case of recycling to the crystallization stage or concentration stage before crystallization the advantage consists in recycling a non-reacted phenol and a non-crystallized BPA which decreases significantly a raw material consumption.
• An additional advantage resulting from recycling the mother liquor to the synthesis stage consists in a limitation of formation of 2-(2- hydroxyphenyl)-2-(4-hydroxyphenyl)propane (so called o,p'-BPA isomer) as then the system approximates more closely the state of equilibrium of the p,p'-BPA and o,p'-BPA isomers.
• Recycling the mother liquor does not solve fully the problem of byproducts as they are cumulated, and one method for solving this problem lies in discharging a part of the post-reaction stream from the process with the aim to maintain their concentration at an acceptable level. Even, when phenol is distilled from this stream, so this indispensable process affects undesirably economical factors of the process for producing BPA.
• a process of catalytic decomposition of by-products is considered in the patent literature as an introduction to the process of a BPA synthesis from products of this decomposition, carried out most frequently in the presence of macroporous ion-exchange resins as catalysts.
• the isomerization reaction allows to convert o,p'-BPA into p,p'-BPA as well as, according to some reports, also trisphenols, first of all, 2,4-bis-[2-(4-hydroxyphenyi)- isopropyl]phenol (JP 08333290) appearing among them in most considerable quantities.
• JP 08333290 2,4-bis-[2-(4-hydroxyphenyi)- isopropyl]phenol
• a purpose of the invention was the development of a process for producing bisphenol A of clear and stable colour in a liquid state, which is characterized by good efficiency and selectivity. It has been found unexpectedly that recycling a mother liquor to the last synthesis stage, as compared with a variant in which its recycling to the reactor of the first stage, allows both to limit the number of by-products other than the o,p'-
• Li a process in which advantages of recycling the mother liquid to the third stage of condensation reaction are used up, and in the case of using the fractionation of products from catalytic decomposition and recycling only phenol to the process, the indices of a raw material consumption are not satisfying in view of the fact that the o,p'-BPA isomer, which is formed in such a technological variant in considerable quantities, forms in conditions of catalytic decomposition a considerable amount of isopropenylphenols and their oligomers which are discharged from the process.
• the process for producing bisphenol A according to the invention uses the isomerization of o,p'-BPA into p,p'-BPA and recycling the isomerizate to crystallization, as well as a catalytic decomposition of the stream of post-crystallization liquors and fractioning the decomposition products, and next recycling to the process phenol only resulting from the decomposition process. It allows to avoid problems associated with the new kinds of by-products, and at the same time to ensure high indices of the conversion of a raw material into bisphenol A.
• the essence of the process of the invention consists in the fact that the condensation reaction of acetone and phenol is carried out in a multi-stage reaction system with an interstage control of the reaction temperature and acetone concentration as well as a control of water concentration before the last stage of the reaction system by recycling a part of post-crystallization liquors from a solvent crystallization to the stream directed to the last reactor, while metering in a continuous manner to the system of reactors containing a catalyst the reaction mixture comprising acetone and phenol.
• reaction mixture comprising acetone, phenol and products of their condensation
• a catalyst in a 2-5-stage reaction system at a temperature 323-348 K
• process parameters are selected in such a way that the molecular ratio of o,p'-BPA to p,p'-BPA isomers at the exit of the first reaction stage is not more than 5/100 and the molecular ratio of o,p'- BPA to p,p'-BPA isomers at the entry to the last reaction stage is not less than 7/100.
• proportions of charge streams to the multi-stage reaction system are selected in such a way that the molecular ratio of water to acetone in the reaction mixture comprising phenol, acetone, water, BPA-isomers and byproducts, which is contacted with a catalyst at a temperature 323-348 K, is not more than 0,5 at the entry to the first reaction stage and not more than 1.2 at the last reaction stage of the multi-stage reaction system.
• the mixture of distilled phenols recovered from technological streams as a result of concentrating a post-reaction mixture from the multi-stage reaction system and from post-crystallization liquors as well as from a thermal decomposition of the BPA/phenol adduct and from rectification with simultaneous catalytic degradation of phenol derivatives is added to the fresh phenol and directed to the first stage of the multi-stage reaction system. It is preferred when a part of the post-crystallization liquor stream from crystallization of the BPA/phenol adduct, recycled to the multi-stage reaction system, is mixed at the entry to the last reaction stage with a post-reaction mixture from the reaction stage before last in a proportion from 1:1 to 3 : 1.
• BPA/phenol adduct are divided into two streams, whereby the larger stream consisting not more than 95 cg/g of the exit stream of liquors is directed to the last stage of the multi-stage reaction system, whereas the second stream is concentrated by distilling off a part of phenol so that a mass fraction of bisphenol A in this stream is not less than 12 cg/g, the concentrated stream being divided into two parts, one part of which is rectified with simultaneous catalytic degradation of phenol derivatives, and the second part of post-crystallization liquors is directed to isomerization.
• concentration of the post-reaction mixture from the multi-stage reaction system is carried out in such a way that the water content in post- crystallization liquors from crystallization of the BPA/phenol adduct is not more than 0.4 cg/g.
• crystallization of the adduct is carried out so that the content of the p,p'-BPA isomer in a filtrate is not more than 12 cg/g, and the ratio of o,p'-BPA to p,p'-BPA isomers is not less than 10/100.
• the rectification with simultaneous degradation of phenol derivatives from a part of the stream of concentrated post-crystallization liquors is carried out in the presence of strong inorganic bases KOH or NaOH, at a temperature at least 443 K under reduced pressure not higher than 150 mm Hg, rectification parameters being selected so that phenol resulting from this process and recycled to the multi-stage reaction system comprises not more than 0.05 cg/g of isopropenylphenol (IPP).
• IPP isopropenylphenol
• not more than 85 cg/g of the stream of concentrated post- crystallization liquors are isomerized in the presence of a macroporous, sulphonated ion-exchange catalyst at a temperature 328-353 K with a liquid hourly space velocity (LHSV) of 0.2-5 m 3 /(m 3 h), the process of isomerization being carried out so that an increment of the total by-products resulting from isomerization is not more than 0.2 cg/g.
• LHSV liquid hourly space velocity
• the effluent from fractional crystallization, enriched in the o,p'- BPA isomer, is dissolved in the isomerizate at a temperature not lower than 353 K in a proportion from 1 :5 to 1 :20.
• Designations used in these tables are as follows: Ac - acetone, H 2 O - water, PhOH - phenol, p,p'-BPA - 2,2-bis-(4-hydroxy- phenyl)propane, o,p'-BPA - 2-(2-hydroxyphenyl)-2-(4-hydroxyphenyl)propane, BPR - by-products, other than o,p'-BPA, from the condensation reaction of acetone and phenol.
• a LHSV is defined as a number of volumetric units of liquids flowing for one hour through the catalyst unit in a state which is assumed by the catalyst in conditions existing in a reactor.
• the post-reaction solution from the stage I is cooled in a membrane heat exchanger to a temperature 55 0 C, and then to the solution is added a portion of acetone in such an amount so that its concentration is 2.54 cg/g (Table 2).
• the solution of acetone, phenol and their condensation products is contacted again with the ion-exchanger catalyst as a result of which the solution temperature increases from 55 0 C to 66 0 C, whereas the content of the p,p'-BPA isomer increases to the level of 12.5 cg/g (composition of the post-reaction mixture from the synthesis stage II is shown in Table 2).
• the post-reaction mixture from the reaction stage II is mixed with post-crystallization liquors from solvent crystallization of the BP A/phenol adduct in a proportion 1.0:1.3.
• the stream of post-crystallization liquors which is used for mixing with the post-reaction solution from the stage II, consists 74 cg/g of the total amount of liquors from the solvent crystallization.
• the compositions of solutions before and after mixing are shown in Table 3.
• the homogeneous solution of post-crystallization liquors and the solution after the synthesis stage II are cooled to a temperature 57 0 C, and, subsequently, acetone is added up to the content of 2.7 cg/g in this stream, and it is contacted with the ion-exchanger catalyst in the synthesis stage III.
• acetone and phenol condensation at the synthesis stage III the temperature of a reacting solution increases from 57 0 C to 69 0 C, and the solution of composition shown in Table 4 is obtained at the reactor exit.
• the solution leaving the multi-stage reaction system trickles through a 100 mesh filtration gauze and is concentrated by evaporation of water, acetone and a part of phenol at a temperature 125-130 0 C under reduced pressure 50 mm Hg.
• the stream compositions are shown in Table 5.
• Table 5 Concentration of the reaction solution from the synthesis stage III
• Crystallization of the BP A/phenol adduct from a phenol solution is carried out in an agitated crystallizer.
• a homogeneous solution of bisphenol A of composition shown in Table 6 is placed in a crystallizer equipped with a mechanical agitator and an electronically regulated cooling system which enables to lower a temperature with a set rate.
• the temperature of BPA-solution is decreased with the rate 5 °C/h from 80 0 C to 55 0 C and with the rate of 1 °C/h from 55 0 C to 50 0 C.
• the crystallized BPA/phenol adduct is isolated from liquors by filtration at a temperature 50 0 C, using a vacuum filter and without washing adduct crystals.
• Post-crystallization liquors of composition shown in Table 6 are recycled to the process according to previously given methodics.
• the BP A/phenol adduct obtained as a result of described operations is melted at a temperature 120 0 C and subjected to thermal decomposition.
• the adduct decomposition is carried out in a falling film evaporator at a temperature 165 0 C under reduced pressure 20 mm Hg, and, subsequently, the raw bisphenol A of phenol content more than 1.0 cg/g is additionally steam-stripped at a temperature 170 0 C under pressure 15 mm Hg with the aim to decrease a phenol content less than 0.5 cg/g.
• a part of post-crystallization liquors in an amount of 24 cg/g of the total mass of liquors is concentrated by distillation at temperatures 125-130 0 C under pressure 25 mm Hg.
• the stream of liquors is concentrated to the content 15 cg/g of the p,p'-PBA isomer in the solution.
• Table 7 The compositions of post-crystallization liquor streams before and after concentration are shown in Table 7.
• the concentrated post-crystallization liquors are divided into two parts, the stream of 72.5 cg/g being directed to isomerization, whereas the stream of 27.5 cg/g is degraded catalytically with simultaneous rectification of the degradation products of phenol derivatives.
• the catalytic decomposition of phenol derivatives is carried out in a reactive rectification column at a temperature 190 0 C, under pressure 120 mm Hg, in the presence of 0.1 cg/g of sodium hydroxide (NaOH).
• NaOH sodium hydroxide
• the distillate from the rectification column is re-distilled to obtain, finally, phenol of 4-isopropenylphenol (PIPH) content less than 0.01 cg/g.
• the distilled phenol from the catalytic decomposition of phenol derivatives is recycled to the reaction stage I.
• a part of the stream of concentrated liquors in an amount of 72.5 cg/g is isomerized at a temperature 65 0 C.
• the concentrated liquors of composition shown in Table 7 are contacted with the macroporous catalyst LEWATIT K2649, in the hydrogen form, of an average pore diameter 65 nm, and with LHSV of 0.5 m 3 /(m 3 h).

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• 2007
  • 2007-02-14 PL PL381757A patent/PL210812B1/pl unknown
• 2008
  • 2008-02-14 UA UAA200908556A patent/UA103301C2/uk unknown
  • 2008-02-14 WO PCT/PL2008/000016 patent/WO2008100165A1/en active Application Filing
  • 2008-02-14 DE DE112008000300T patent/DE112008000300T5/de not_active Ceased
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