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7435318 |
Ionic liquids as selective additives for separation of close-boiling or azeotropic mixtures
The invention relates to a process for separating close-boiling, homo- and heteroazeotropic mixtures by using ionic liquids. Due to the selectivity and unusual combination of properties of the...
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7410556 |
Purification of aqueous solutions of organic acids
The invention relates to a method and a device for the purification of an aqueous solution of an organic acid having a boiling point at atmospheric pressure of less than 450° C., which further has...
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7241365 |
Material for a facility for the production of anhydrous formic acid
The invention relates to an apparatus and a process for the preparation of anhydrous or substantially anhydrous formic acid. This apparatus is constructed partly or entirely of substantially...
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6793777 |
Method for separating and purifying an aqueous mixture that mainly consists of acetic acid and formic acid
The invention relates to a method for separating and purifying an aqueous mixture that mainly consists of acetic acid, formic acid and high-boiling substances by extraction with a solvent in a...
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6695952 |
Method for the separation of and purification of an aqueous mixture consisting of the main components acetic acid and formic acid
A method for the separation and purification of an aqueous mixture of main components, namely acetic acid and formic acid and non-volatiles by extraction, uses a solvent in a circulatory system. A...
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6179966 |
Method for producing acrylic acid
The present invention concerns a method for producing acrylic acid which involves subjecting an acrylic acid-containing aqueous solution obtained by catalytic vapor phase oxidation of propylene...
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5980696 |
Dehydration of acetic acid by azeotropic distillation in the production of an aromatic acid
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...
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5976324 |
Removal of water from reaction mixtures
A process as been found for the removal of water from reaction mixtures of acids or acid anhydrides or of aqueous alkali metal hydroxide solutions with alcohols using vapor permeation/pervaporation...
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5873981 |
Recovery of anhydrous acids
A is a process for removing water from an alkanesulfonic acid such as methanesulfonic acid or ethanesulfonic acid by mixing an azeotropic excess of a phenolic compound with water and the...
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5624566 |
Method and apparatus for recovering carboxylic acids from dilute solutions
A method for recovering carboxylic acids from a dilute aqueous solution thereof having a concentration below about ten percent (10%) by weight, which includes passing the dilute acid solution...
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5603813 |
Purifying distillation of vinyl formate
Vinyl formate containing formic acid, acetaldehyde and water following synthesis is separated from formic acid and water in a first distillation stage and from acetaldehyde in a second stage to...
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5492625 |
Method of recovering carboxylic acids from dilute solutions
A method for recovering carboxylic acids from a dilute aqueous solution thereof having a concentration below about ten percent (10%) by weight, which includes passing the dilute acid solution...
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5399751 |
Method for recovering carboxylic acids from aqueous solutions
Disclosed is a method for recovering carboxylic acids having from one to ten carbon atoms, and particularly formic acid, acetic acid and mixtures of formic and acetic acids, from aqueous solutions,...
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5384413 |
Process for the preparation of tetrafluorophthalic acid and/or tetrafluorophthalic anhydride
The present invention relates to a process for the preparation of tetrafluorophthalic acid and/or tetrafluorophthalic anhydride by reacting a compound of the formula ##STR1## in which X is a...
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5312935 |
Purification of fluorinated carboxylic acids
Fluorinated carboxylic acids which do not have the required purity for use as emulsifier in the polymerization of fluorinated monomers can, if necessary after prior de-watering, be treated with...
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5296639 |
Adipic acid purification
A process for purification of adipic acid during crystallization by modifying the crystal morphology to decrease incorporation of impurities through the introduction of an effective amount of an...
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5206433 |
Preparation of formic acid
Anhydrous or substantially anhydrous formic acid is prepared by hydrolyzing methyl formate in the presence of a formamide and then obtaining the formic acid from the hydrolysis mixture by...
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5173156 |
Dehydration of formic acid by extractive distillation
Formic acid cannot be completely removed from formic acid--water mixtures by distillation because of the presence of the maximum azeotrope. Formic acid can be readily removed from mixtures...
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5154800 |
Dehydration of acrylic acid by extractive distillation
Acrylic acid cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. Acrylic acid can be readily separated from water by...
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5104492 |
Recovery of carboxylic acids from water by precipitation from organic solutions
Carboxylic acids are recovered from wet organic solutions by reducing the solutions' water content thus causing the acids to precipitate as recoverable crystals.
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5059327 |
Cross-linked separation membrane and process for pervaporation
A preparation membrane for pervaporation which comprises a crosslinked reaction mixture of a polyvinyl alcohol or polyvinyl alcohol copolymer and a polystyrene sulfonic acid or polystyrene sulfonic...
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4978430 |
Method for dehydration and concentration of aqueous solution containing organic compound
An improved method for dehydration and concentration of an aqueous solution containing an organic compound is disclosed. The solution is evaporated to produce a gaseous mixture comprising an...
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4938846 |
Preparation of anhydrous alkanesulfonic acid
A process for the removal of water from a lower alkanesulfonic acid-water mixture by causing the mixture to run down the internal walls of two vertical evaporator columns operated in series, is...
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4898644 |
Removal of volatile acids from aqueous solutions
A process for removing volatile acids from aqueous solutions which involves steam stripping a volatile acid from an aqueous solution and contacting the vaporized acid with a reactable cation to...
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4838998 |
Process for separating sulfuric acid and carboxylic acids
The amount of water required to effect efficient separation of a mixture of sulfuric acid and carboxylic acids by distillation, is reduced, by diluting the mixture while in the distillation column...
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4736062 |
Process for preparing methacrylic acid
A process is disclosed for producing an alpha-, beta-ethylenically unsaturated monocarboxylic acid compound which comprises the aldol-type condensation of a saturated aliphatic monocarboxylic acid...
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4735690 |
Dehydration of impure formic acid by extractive distillation
Impure formic acid cannot be completely removed from formic acid-water-impurity mixtures by distillation because of the presence of the maximum azeotrope between formic acid and water. Formic acid...
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4670105 |
Dehydration of propanoic acid by extractive distillation
Propanoic acid cannot be completely removed from propanoic-water mixtures by distillation because of the presence of the minimum azeotrope. Propanoic acid can be readily removed from mixtures...
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4661208 |
Method for dehydrating distillation of an aqueous solution of carboxylic acid
The invention provides a means for greatly saving the thermal energy consumption in the dehydrating distillation of an aqueous solution of a carboxylic acid such as acetic acid by use of an...
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4599144 |
Process for recovery of methacrylic acid
Process is disclosed for treating the reaction product of propionic acid and formaldehyde to recover methacrylic acid from an aqueous effluent wherein said effluent contains methacrylic acid,...
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4576683 |
Method for separating carboxylic acids from mixtures with non-acids
A method for separating carboxylic acids from mixtures with non-acids by an extractive distillation method using a lactam with a 5- or 6-membered ring, preferably N-methyl-2-pyrrolidone, as an...
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4554054 |
Methacrylic acid separation
A process to recover acrylic acid or methacrylic acid by using a split quench process which allows acrylic acid or methacrylic acid to be recovered from the resulting aqueous solutions by a...
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4518462 |
Distillation process for purifying methyl methacrylate
In purifying methyl methacrylate by feeding a feed mixture containing methanol, methyl methacrylate and 0.05 to 2% by weight, based on the weight of the methyl Methacrylate, of methyl isobutyrate...
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4450047 |
Process for recovering anhydrous alkanesulfonic acids by reduced pressure, falling film evaporation
Water is removed from methanesulfonic acid to produce an anhydrous product of high purity by spraying wet methanesulfonic acid (MSA) onto the walls of a vertical, heated tube which is maintained at...
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4444881 |
Recovery of organic acids from a fermentation broth
A process is provided for the recovery of organic acids from dilute aqueous solutions. The acid in the form of its calcium salt is treated with a tertiary amine carbonate and the resulting...
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4401514 |
Method for the recovery of furfural, acetic acid and formic acid
A method of recovering or extracting chemicals, such as furfural, formic acid, acetic acid and other organic compounds from acidic hydrolysates of plants or vegetable matter, especially spent...
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4365080 |
Production of dimethyl esters
This invention provides an improved process for the separation and recovery of byproducts associated with the isolation of C 4 -C 6 dicarboxylic acids contained in a waste byproduct stream...
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4344897 |
Process for the preparation of percarboxylic acid solutions
In a process for the continuous preparation of pure organic solutions of percarboxylic acids having 2 to 5 carbon atoms, by (a) contacting aqueous hydrogen peroxide with a carboxylic acid...
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4339596 |
Treatment of byproduct stream from adipic acid manufacture
In one embodiment, this invention provides a process for converting a dilute aqueous filtrate byproduct stream from adipic acid manufacture into a concentrated methanolic solution which does not...
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4269666 |
Recovery of acrylic acid by reversal of acrylic acid/water relative volatility
An aqueous solution of acrylic acid and water containing 30 wt. % or less acrylic acid, can be concentrated to 40-60 wt. % acrylic acid in the overhead of a distillation column through the addition...
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4262140 |
Production of anhydrous or substantially anhydrous formic acid
A process for the production of anhydrous or substantially anhydrous formic acid by hydrolysis of methyl formate which is carried out in a column having an upper fractionating section, a middle...
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4230887 |
Recovery of anhydrous acids
C 2 -C 6 monocarboxylic and dicarboxylic acids are scrubbed from gas phase mixtures of such acids and water by gas absorption techniques utilizing a liquid solvent comprising a polyoxyalkylene...
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4076594 |
Purification of formic acid by extractive distillation
Formic acid is purified by extractive distillation of its aqueous solutions using a basic extractant, followed by distillation of the bottom mixture first obtained, the extractant used being...
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4039428 |
Purification of propionic acid
A process is provided for producing ultra-pure propionic acid, i.e., acid containing less than 20 parts by weight of iodine per billion parts by weight of acid, wherein crude acid containing water...
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4035242 |
Distillative purification of alkane sulfonic acids
Aqueous solutions of methane sulfonic acid are dehydrated and purified in a two-step fractionation process.
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3989600 |
Distilling H.sub.2 O from aromatic carboxylic acid at a pH exceeding 9
A process for treating an aqueous solution containing organic compounds and having a high chemical oxygen demand (COD) by distilling the aqueous solution at a pH not lower than 9, and recovering...
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3983010 |
Recovery of the formic acid/water azeotrope by distillation
Formic acid is isolated from mixtures containing formic acid, methyl formate, methanol and water by fractional distillation, the mixture being fed into the upper half of the distillation column and...
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3968153 |
Extraction of acrylic acid and/or methacrylic acid with a solvent mixture of methylethylketone and xylene or ethylbenzene
A method for extraction of acrylic acid and/or methacrylic acid from a solution containing the same by treating the said solution with an organic solvent, which is characterized by using a mixture...
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3957830 |
Manufacture of succinic anhydride
Process for the manufacture of succinic anhydride by eliminating water from succinic acid using a chemically inert hydrophilic solvent which does not form an azeotropic mixture with water, and...
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3868417 |
Separation of acrylic acid from the reaction gases from propylene or acrolein oxidation
On the separation of acrylic acid from reaction gases from the oxidation of propylene or acrolein a countercurrent absorption is carried out with at least 8 parts by weight of carboxylic ester per...
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