CN107867990A - The method for preparing terephthalic acid (TPA) - Google Patents

Abstract

A kind of method that terephthalic acid (TPA) is prepared by paraxylene.This method includes forming the mixture for including paraxylene, solvent, bromine source, catalyst and ammonium acetate；With by making mixture contact p xylene oxidation under oxidative conditions with oxidant to produce the solid oxidation product for including terephthalic acid (TPA), paratolunitrile, 4 carboxyl benzaldehydes.Solvent includes the carboxylic acid with 17 carbon atoms, and catalyst includes at least one of cobalt, titanium, manganese, chromium, copper, Ni-V-Fe, molybdenum, tin, cerium and zirconium.

Description

The method for preparing terephthalic acid (TPA)

Technical field

The present invention relates to the method that terephthalic acid (TPA) is prepared by the raw material comprising paraxylene.More particularly, the present invention relates to And oxidation of the paraxylene in the presence of solvent, catalyst, bromine source and ammonium acetate.

Background technology

The oxidation of Alkylaromatics such as toluene and dimethylbenzene is important business method.It can obtain a variety of oxidation productions Thing, including aromatic carboxylic acid is for example for the terephthalic acid (TPA) (Isosorbide-5-Nitrae-benzene dicarboxylic acid) in polymer industry.

US6,355,835 is disclosed by oxygen in the presence of being used as solvent, cobalt salt as catalyst and initiator in acetic acid Change the method that xylene isomer liquid phase oxidation is prepared by benzene dicarboxylic acid by using oxygen or air.It is after oxidation step The reactant mixture is flashed to remove the crude benzol two of volatile materials and cooling and filtering to obtain as solid product Carboxylic acid and filtrate.Also disclose and recrystallize crude benzol dicarboxylic acids to obtain the recycling of at least 99% purity and filtrate.

It is also known to the art that for example aromatic aldehyde, aromatic alcohol, aromatic ketone and aromatic carboxylic acid can be under oxidative conditions for oxidation product And/or solidify or crystallize when the reaction mixture is cooled.Therefore, the mixture of oxidation product can be produced, it may be needed into one Step is processed to improve the purity of required product.In the preparation of terephthalic acid (TPA), oxidation product is commonly referred to as crude terephthalic acid, Because it contains impurity, including chromogen and intermediate oxidation product, especially 4- carboxyl benzaldehydes (4-CBA).To be polymerize Item level or the terephthalic acid (TPA) of purification, various purification steps are as known in the art, including：Washed with water and/or solvent Crude terephthalic acid, other oxidations or crystallisation step, and make the crude terephthalic acid solution of dissolving and hydrogen generally include to contain Have and reacted under the hydrogenation conditions of the catalyst of palladium and carbon.Usually using several purification steps.

US7,692,036 discloses the optimal side for liquid phase oxidation that is more effective and economically carrying out oxidizable compounds Method and equipment.The liquid phase oxidation is carried out in the bubble-column reactor for providing highly effective reaction at relatively low temperature.When Oxidized compound is the product of paraxylene and oxidation reaction when being crude terephthalic acid (CTA), the CTA products can be passed through into ratio The more economical technology that may be used if CTA is formed by conventional high temperature method for oxidation purifies and separation.

There remain a need in the art of the alternative of terephthalic acid (TPA) to be prepared.In addition, purify relatively inexpensive and less time-consuming system The method of standby terephthalic acid (TPA) and terephthalic acid composition is preferable.With different pollutants than terephthalic acid (TPA) group Compound may be provided in other application the new intermediate for being used as raw material.

The content of the invention

Consolidating with high-purity can be provided by having found the presence in p xylene oxidation into ammonium acetate during terephthalic acid (TPA) Body terephthalic acid product.In one embodiment, solid terephthalic product has lower than gained in conventional method Paratolunitrile content and lower 4- carboxyl benzaldehyde contents.

In one embodiment, the present invention is a kind of method that terephthalic acid (TPA) is prepared by paraxylene, method bag Include：Form the mixture for including paraxylene, solvent, bromine source, catalyst and ammonium acetate；With by making mixture and oxidant Contact under oxidative conditions and p xylene oxidation is included into terephthalic acid (TPA), 4- carboxyl benzaldehydes and paratolunitrile to produce Solid oxidation product.Solvent include with 1-7 carbon atoms carboxylic acid, and catalyst include cobalt, titanium, manganese, chromium, copper, nickel, vanadium, At least one of iron, molybdenum, tin, cerium and zirconium.

Purification step of the present invention can further comprise one or more solvent contact procedures.Solvent contact procedure includes making admittedly In the solid oxidation product of body terephthalic acid composition such as washing and the carboxylic acid and mother liquor comprising water, with 1-7 carbon atoms extremely Second solvent of one item missing is contacted to produce the second Solid terephthalic acid composition.In one embodiment, the second solvent Selected from mother liquor, the carboxylic acid with 1-7 carbon atoms, water and combinations thereof.Solvent contact can combine impurity from solid terephthalic acid Filtered out in thing, and/or Solid terephthalic acid composition can be partially or completely soluble in solvent.Solvent contact conditions include solvent Contact Temperature.Solvent Contact Temperature can be less than oxidizing temperature.In one embodiment, solvent Contact Temperature is lower than oxidizing temperature At least 20 DEG C.Solvent contact for example can be put into practice in one or more crystallizers, the crystallizer in some conventional methods After oxidation reactor.Second terephthalic acid composition can solidify in the second solvent of solvent contact procedure, precipitates or tie It is brilliant.Second terephthalic acid composition has pair relative to the Solid terephthalic acid composition being introduced into solvent contact procedure The higher terephthaldehyde's acid content of phthalic acid content, because at least some impurity have been reduced.It will can be prepared by the present invention Solid oxidation product is purified by known method including the use of step of hydrogenation.In typical embodiments, it is not necessary to hydrogenation step Suddenly.In one embodiment, the inventive method includes the purification step that one or more does not include step of hydrogenation.That is, purify The processing step that processing step may be selected from by washing, separating, drying, solvent contact and combinations thereof forms.

Embodiment

Embodiment is proposed so that some aspects of the present invention and benefit is expanded on further and is not considered as to limit the scope of the present invention.

Embodiment 1：

Experimental arrangement：In fume hood, the component for the given experiment amount will be loaded into Parr reactors, sealing is anti- Answer device.Parr reactors include gas distributor so that gas is scattered in liquid by 1.6mm perforates, mechanical gas migration stirs Device and baffle plate are mixed to ensure to be thoroughly mixed.Parr reactors are arranged in heater assembly at room temperature and connect gas supply line It is connected on reactor and condenser is connected to reactor outlet.During operation, gas is by condenser, then trap, Then back pressure regulator leaves reactor.Emergency air inlet with burst disk, and thermocouple are connected on reactor.Will cooling Water recirculator is connected on condenser and starts to recycle cooling water.Used under room temperature and 1.4MPa (g) (200psig) Nitrogen pressure test Parr reactors in the absence of pressure until reduce by 15 minutes.The back pressure regulator of reactor outlet is arranged to Experimental pressure and under a nitrogen pressure test reactor.Start temperature of reactor being increased to experimental temperature in a nitrogen atmosphere. Always follow all operation instructions of specific reactor, including the temperature and pressure limit.When reactor reaches required temperature, open Begin to test the temperature of reactor and pressure during speed adds air and the whole experiment of monitoring.During experiment, to reactor In air stream be maintained at for 1250 standard cm/ minutes, pressure is maintained at 4.1MPa (g), and agitator is maintained at 31600rpm. Heater is closed during off-test, air stream is cut off and cools down reactor.When reactor is cooled to less than about 35 DEG C, open Counterbalance valve, stop cooling water and remove and empty reactor to obtain solid oxidation product and mother liquor.

Mother liquor and product are filtered under vacuo to separate solid and liquid.Then by solid at room temperature with about 100cc Deionized water is mixed and is decanted.Deionized water at room temperature is mixed and is decanted and is repeated twice.4th time is washed with deionized water Wash and be heated to about 95 DEG C, kept for 30 minutes, then filtered.Solid is dried into 8-24 hours at 80 DEG C before analysis.

Claims (3)

1. a kind of method that terephthalic acid (TPA) is prepared by paraxylene, methods described include：Formed comprising paraxylene, solvent, The mixture in bromine source, catalyst and ammonium acetate；With will be to two by making mixture be contacted under oxidative conditions with oxidant To produce solid oxidation product, the solid oxidation product includes terephthalic acid (TPA), 4- carboxyl benzaldehydes and to first toluene oxidation Benzoic acid；Wherein solvent include with 1-7 carbon atoms carboxylic acid and optional water, catalyst include cobalt, titanium, manganese, chromium, copper, nickel, At least one of vanadium, iron, molybdenum, tin, cerium and zirconium.

2. the ratio between method according to claim 1, wherein solvent and Alkylaromatics are about 1.5:1 to about 6:1 weight meter.

3. according to the method for claim 1 or 2, wherein oxidizing condition includes about 0 to about 6MPa (g) pressure and about 125 to about 275 DEG C of temperature.