摘要:
Processes for the production of aromatic carboxylic acids is disclosed. The aromatic acids are produced by the liquid phase oxidation of a suitable acid precursor in a reaction medium comprising benzoic acid. According to one embodiment, the oxidation is carried out under plug-flow reaction conditions in a plug-flow reactor. The plug-flow conditions can be achieved by the use of a series of continuous stirred tank reactors. In another embodiment, the oxidation is carried out in tow continuous stirred tank reactors fluidly connected in series. The preferred oxidation products are terephthalic acid, isophthalic acid, trimellitic acid, 2,6-naphthalene dicarboxylic acid, 1,5-napthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid and phthalic acid.
摘要:
Disclosed are polyoxyethylated castor oils produced by preparing a suspension of activated charcoal and a polyoxyethylated castor oil; and separating the activated charcoal from the polyoxyethylated castor oil. The process removes impurities such as colorants and alkali metal cations. Also disclosed are compositions containing the treated castor oil and an active agent such as a pharmaceutical agent. The formulations have prolonged storage stability.
摘要:
Disclosed is a process for purifying 2,6-naphthalene dicarboxylic acid produced by disproportionation and more efficiently recycling byproduct dipotassium salts which includes the steps of: a) Contacting an aqueous solution containing the disalt of 2,6-NDA(2,6-K2NDA) with carbon dioxide to form as a precipitate the monopotassium salt of 2,6-NDA (KHNDA) and an aqueous solution containing 2,3-KHNDA, K2NDA, and potassium bicarbonate; b) Disproportionating said monopotassium salt (KHNDA) to form 2,6-NDA and an aqueous solution containing K2NDA, and potassium bicarbonate; c) Separating said 2,6-NDA and concentrating said aqueous solution containing K2NDA and potassium bicarbonate by reverse osmosis.
摘要:
Methods are disclosed for recovering dicarboxylic acids, particularly long chain dicarboxylic acids, from a feed containing at least one impurity. The methods utilize melt crystallization involving the steps of: (a) contacting the feed in a molten state with a crystallization surface, (b) cooling the crystallization surface to cause the formation of crystals comprising dicarboxylic acids and a mother liquor, (c) removing the mother liquor from the crystals, (d) heating the crystals to cause a partial melting of the crystals to form a sweat, (e) removing the sweat from the crystals, (f) melting the remaining crystals to form product, and (g) recovery of the product. The methods may be repeated as is necessary to obtain the desired purity. The purity of the dicarboxylic acids product obtained is generally greater than 96.0 weight % dicarboxylic acids based on the total weight of the product. Methods are also described for producing and recovering dicarboxylic acids by fermentation and melt crystallization.
摘要:
Process for producing pure terephthalic acid having improved means for recovering and/or recycling terephthalic acid precursors, residual acetic acid and other reaction by-products, such as methyl acetate.
摘要:
A method is provided to produce dicarboxylic or tricarboxylic aromatic acid from salts of such acids, the method including the steps of providing an aqueous solution of a salt of a dicarboxylic or tricarboxylic aromatic acid, the aqueous solution having a pH of about 7 or greater; contacting the aqueous solution with sufficient carbon dioxide to lower the pH of the aqueous solution resulting in precipitation of at least a portion of the dicarboxylic or tricarboxylic aromatic acid; separating precipitated dicarboxylic or tricarboxylic aromatic acid from the solution; and recovering carbon dioxide from the solution.
摘要:
Disclosed are halide-free catalyst compositions for the disproportionation/isomerization of aromatic carboxylic acid salts. In one embodiment the catalyst comprises a mixed catalyst of compounds of copper, zinc, and zirconium; and, in a second embodiment, the catalyst comprises a copper compound treated with a base, optionally used with a promoter. Both halide-free catalysts provide advantages with respect to metallurgic problems, as well as good stability, activity and selectivity, and the later is faster kinetically at lower temperatures.
摘要:
A process for the production of columnar crystals of 6-hydroxy-2-naphthoic acid, which comprises dissolving crude 6-hydroxy-2-naphthoic acid in an aqueous medium, adding seed crystals of 3-hydroxy-2,7-naphthoic acid or seed columnar crystals to the solution, and cooling the resulting mixture to conduct crystallization; and columnar crystals of 6-hydroxy-2-naphthoic acid produced by the process, which exhibit in the X-ray diffraction a peak 2 DOLLAR g (u) ranging from 16.8 to 17.8 and/or from 21.3 to 22.3 and have a high apparent specific gravity and excellent fluidity.
摘要翻译:制备6-羟基-2-萘甲酸的柱状结晶的方法,其包括将6-羟基-2-萘甲酸溶于水性介质中,加入3-羟基-2,7-萘甲酸的晶种或 将晶体柱状晶体加入到溶液中,并冷却所得混合物进行结晶; 和通过该方法产生的6-羟基-2-萘甲酸的柱状晶体,其在X射线衍射中显示峰值2 DOLLAR g(u)为16.8至17.8和/或21.3至22.3,具有高的表观 比重和流动性好。
摘要:
The invention concerns a method for making adipic acid, more particularly adipic acid crystals. More precisely, it concerns a method for treating adipic acid crystals derived from crystallisation which consists in dispersing the adipic acid crystals collected at the output of crystallisation in a liquid medium, stirring said liquid medium, then separating said crystals and optionally drying them. The shape of the crystals is modified to obtain pebbles with substantially smooth surface.