摘要:
This invention relates to a process for manufacturing terephthalic acid and more particularly, to a process of manufacturing and recovering the highly purified terephthalic acid using an alkali weight-reduction waste water discharged from weight-reduction process in a polyester textile dyeing complex, in accordance with the practice of this invention comprising the following procedures: polyethylene terephthalate (hereinafter referred to "PET") waste scrap materials are hydrolyzed to prepare the slurry of disodium terephthalate. Then, said slurry dissolved in water is adsorbed to remove impurities, and followed by acid-neutralization to obtain terephthalic acid of this invention.
摘要:
An improved process for preparing an aromatic dicarboxylic acid wherein the improvement resides in dehydrating and recovering solvent from a feed stream having from 20% to 40% by weight water via azeotropic distillation with organic phase reflux using an entrainer selected from isobutyl acetate, n-propyl acetate or an entrainer with a boiling point between isobutyl acetate and n-propyl acetate.
摘要:
Terephthalic acid is produced by oxidation of para xylene, purified in an aqueous phase and recovered by precipitating a purified product from the aqueous phase, the aqueous phase mother liquor is then cooled or evaporated to produce a further less pure precipitate and a second mother liquor and the less pure precipitate is returned to the reaction medium and/or the water of the second mother liquor is used to dissolve the crude solid and/or the second mother liquor is treated to recover water which is used to wash the precipitate recovered from the aqueous solution. The process produces better yields of terephthalic acid, reduces the use of water and reduces problems in the disposal of polluted waste water.
摘要:
This invention relates to a hydroformylation process which comprises reacting one or more olefinic unsaturated compounds with carbon monoxide and hydrogen in the presence of a metal-organopolyphosphite ligand complex catalyst and optionally free organopolyphosphite ligand, and an amount of a sterically hindered organophosphorus ligand different from the organopolyphosphite ligand of said metal-organopolyphosphite ligand complex catalyst, to produce one or more aldehydes. The sterically hindered organophosphorus ligands are useful as indicators of organopolyphosphite ligand depletion in said hydroformylation process.
摘要:
A process for preparing aromatic carboxylic acids by the exothermic liquid-phase oxidation reaction of an aromatic feedstock compound, wherein energy is efficiently recovered from the exothermic oxidation reaction.
摘要:
A process for producing highly pure terephthalic acid comprising: (a) oxidizing a p-phenylene compound in the liquid phase in the presence of acetic acid, to produce a liquid-phase oxidation product, (b) separating the liquid-phase oxidation product into the following: (i) a first mother liquid containing acetic acid and (ii) a crude terephthalic acid, (c) evaporating, in whole or in part, the first mother liquid, to produce a vapor, (d) feeding the vapor, or a condensate thereof, to an intermediate stage of a distillation tower, carrying out an azeotropic distillation and withdrawing through a bottom of the distillation tower a concentrated acetic acid, (e) subjecting the crude terephthalic acid to a refining treatment, which is a catalytic hydrotreatment, a catalytic treatment or a recrystallization, which is carried out in the presence of is water, (f) cooling and crystallizing the resultant liquid from step (e), to produce a pure terephthalic acid and a second mother liquor, (g) subjecting the second mother liquor to an extraction in the presence of an azeotrope-forming agent to extract aromatic carboxylic acids contained in second mother liquor, to produce a liquid extract, and (h) recycling the liquid extract to the distillation tower in step (d). The process can greatly reduce the effluent water treatment load and enhance the yield of the objective terephthalic acid, in addition to providing recycling of useful reactants.
摘要:
Purified terephthalic acid is prepared by a process of subjecting an aqueous solution of crude terephthalic acid to hydrogenation to reduce impurities, crystallizing this solution to produce a slurry of purified terephthalic acid in an aqueous liquor, and carrying out an integrated separation washing process using a centrifuge having washing facilities.
摘要:
Terephthalic acid is produced by reacting paraxylene with oxygen in a reactor having several vertical stages, the reaction taking place in the liquid phase using acetic acid as solvent and a cobalt-manganese-bromine complex catalyst. During the reaction, a carbon dioxide-containing gas phase is withdrawn from the vapor space of the reactor. The gas phase is cooled to condense vaporized acetic acid therefrom and carbon dioxide is separated from the gas phase and recycled to the vapor space or to the liquid phase or to both of these. In an alternate embodiment, the gas remaining after condensing acetic acid is subjected to catalytic oxidation to oxidize carbon monoxide and methane, if present, to carbon dioxide, and some or all of the carbon dioxide is recycled to the reactor.
摘要:
A process for the preparation of terephthalic acid (TA) from pure dimethyl terephthalate (DMT) and/or DMT intermediate product by hydrolysis in a countercurrent reactor at a conversion of greater than 99% and crystallization to give the solid product, characterized in that the sum of the stripping steam (S) and reaction water (W) satisfies the relationship L.ltoreq.S+W.ltoreq.2L, wherein (L) represents the amount of water necessary to keep the terephthalic acid (TA) produced largely in solution during the reaction and in the bottom of the reactor, and the terephthalic acid produced is crystallized in a crystallization which is free from washing stages.
摘要翻译:一种通过在逆流反应器中以大于99%的转化率通过水解从纯对苯二甲酸二甲酯(DMT)和/或DMT中间产物制备对苯二甲酸(TA)的方法,并且结晶得到固体产物,其特征在于, 汽提蒸汽(S)和反应水(W)的总和满足关系L <= S + W 2L,其中(L)表示保持大部分产生的对苯二甲酸(TA)所需的水量 溶液在反应期间和反应器底部,生成的对苯二甲酸在不含洗涤阶段的结晶中结晶。
摘要:
A terephthalic acid slurry in acetic acid is produced by oxidizing p-xylene in acetic acid, removing water by evaporation of a stream of water and acetic acid, and returning acetic acid to the oxidation step. The terephthalic acid is separated from the reaction medium in a first zone to leave a deposit on a band, the deposit is washed with a first aqueous medium in a second zone, removed from the band in a third zone, and admixed with a second aqueous medium. Reaction medium is passed from the first zone to the oxidation step and terephthalic acid is recovered, preferably after further purification.