Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1999-08-02
2001-05-29
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S483000, C562S485000
Reexamination Certificate
active
06239310
ABSTRACT:
Subject of the invention is the method of recovery of terephtalic acid and ethylene glycol from poly/ethylene terephtalate/ waste.
Still growing global production of poly/ethylene terephtalate/, which is used as a popular material for the production of bottles and containers, industrial shapes, synthetic fibres, insulation foils and other everyday use articles, causes, besides its numerous utility values, a fast increase of its wastes amount.
The chemical nature of poly/ethylene terephtalate/ causes that as a plastic of an extraordinary high resistance against the extremely severe atmospheric conditions, the wastes do not yield to microbiological degradation and a natural decomposition and they last, occupying in the unchanged form and being very noxious and durable pollution of the environment.
At the same time the raw materials for a production of poly/ethylene terephtalate/, i.e. ethylene glycol and terephtalic acid are still expensive.
The manufacture of poly/ethylene terephtalate/ waste for the regranulate, which is then added to the principal raw material in a process of forming any products does not solve the waste problem and similarly, as its harmful combustion, it is a stopgap.
Till now, from the American patent description no. 4.542239 a process of recovery terephtalic acid from poly/ethylene terephtalate/ is known, which is based on a reaction of suitably disintegrated wastes, comprising used containers and bottles of beverages, with a medium, containing ammonium hydroxide at the increased temperature and an increased pressure, and then the acidification of formed aqueous solution of water-soluble diammonium salt of terephtalic acid to precipitate terephtalic acid. A part of the solution remained after separation of terephtalic acid was subjected to the treatment with alkaline medium to separate ammonium, which was recycled together with a second part of the solution, remained after separation of terephtalic acid, as the charge material in a consequent part of substrates.
From the German patent application no. 19629042.2 a method of production terephtalic acid and ethylene glycol from poly/ethylene terephtalate/ waste is known. The process is carried in a slightly alkaline medium of carbonates of the I-st group metals or ammonium carbonate, by the decreased pH value, which does not allow any undesired side reactions and prevents the contamination of products.
In a known method suitably disintegrated poly/ethylene terephtalate/ wastes are subjected to the operation of an aqueous solution of alkali metal or ammonia carbonate while the temperature is increased gradually, preferably up to 200° C., and then the temperature is kept constant till the digestion of polyester is completed. Carbon dioxide, formed during the reaction is permanently carried away from the reaction environment under a constant pressure and is absorbed in an aqueous solution of alkali metal hydroxide, preferably of sodium Na, potassium K or ammonia water till the saturation moment. A reaction mixture, after separation of solid impurities and cooling, is then subjected to an oxidation process, preferably in aqueous solution of hydrogen peroxide of a concentration of 3% b.w., and then the solution is neutralised with an acid solution, preferably mineral acid solution, till the precipitation of terephtalic acid is completed. From a resulted suspension of terephtalic acid in a solution of ethylene glycol and salt of an acid used for the neutralisation a solid phase is separated, which is then subjected to the purification process, including washing and/or crystallisation and drying, which gives in a result terephtalic acid of a desired water content. Ethylene glycol is distilled off from the resulted solution, after evaporation of water and separation the salt of an acid used for neutralisation. Carbonate, formed in a result of absorption of educed carbon dioxide in hydroxide or ammonia solution is then used in a consequent batch, processed according to the known method.
In the method according to the invention, disintegrated poly/ethylene terephtalate/ wastes are heated with a reagent substance, chosen from the group, comprising bicarbonates of ammonia and alkali metals, ammonium carbamate and urea, which substances are used in an aqueous solution in amounts not less than a stechiometric amount at a temperature between 150°-280° C.
After the poly/ethylene terephtalate/ is digested a resulted aqueous solution of terephtalic acid salts is subjected to the further processing according to a method known from the German patent application no. 19629042.2, comprising filtering of a hot solution, neutralisation of a filtrate with a mineral acid, separation of terephtalic acid, washing of terephtalic acid with water and the eventual crystallisation from water, a neutralisation resulted filtrate and separation of ethylene glycol using distillation or extraction.
The preferable course of the reaction carried using a method according to the invention results at the temperatures range between 180-200° C.
The method according to the invention enables a production of high purity products demanded by the market and it gives a possibility of utilisation of wastes, being the durable and noxious pollution of a natural environment.
REFERENCES:
patent: 5545746 (1996-08-01), Benzaria et al.
patent: 839371 (1960-06-01), None
patent: 163385 (1988-09-01), None
Arent Fox Kintner & Plotkin & Kahn, PLLC
Killos Paul J.
LandOfFree
Method of recovery of terephthalic acid and ethylene glycol... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of recovery of terephthalic acid and ethylene glycol..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of recovery of terephthalic acid and ethylene glycol... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503719