Device for purifying formic acid solution with interval azeotropic distillation and method thereof

Abstract

The invention relates to a device for purifying formic acid solution with interval azeotropic distillation and a method thereof. The device comprises a rectification column body, an insulating layer, a tower pot, a heating jacket, a condenser, a phase separator and a product storage tank, wherein, the insulating layer is arranged outside the column body, the lower end of the column body is connected with the tower pot, the upper end is respectively connected with the condenser and the phase separator, and the phase separator is respectively connected with the condenser and the product storage tank. The method comprises the following steps: firstly, cyclohexane is used as entrainer, and dilute formic acid water solution with mass concentration being 10% is initially concentrated to 30%; then, chlorobenzene is used as entrainer, the top of the tower continuously produces azeotrope of chlorobenzene and water; when the top of the tower reaches 95 DEG C-102 DEG C, the mixture of chlorobenzene, formic acid and water is produced, and the mass fraction of the formic acid is 60-70% after phase separating; at last, pressurization rectification is used, the pressure is controlled at 4atm, and the tower pot can obtain 80-85% high-concentration formic acid solution. The invention has the characteristics of reasonable process flow, simple device structure, high efficiency and low cost and is suitable for industrial continuous operation.

Description

technical field [0001] The invention relates to a device and method for purifying formic acid solution by intermittent azeotropic distillation, in particular to purifying 10% dilute formic acid solution into 80-85% higher concentration formic acid by adopting heterogeneous azeotropic distillation. technical background [0002] Formic acid, commonly known as formic acid, is the simplest fatty acid and an important organic chemical raw material. It is widely used in pesticides, leather, textiles, printing and dyeing, medicine and rubber industries. It can also be used to prepare various solvents, plasticizers, and rubber solidification. Agents, animal feed additives and new process synthetic insulin, etc. In the production of medicines and spices and the acid treatment of textiles and leather, a large amount of low-concentration formic acid solution will be produced, which has no practical application value. Recovering low-concentration formic acid and enriching it (w%>85%...

AI Technical Summary

Problems solved by technology

Add new entrainer in water-containing formic acid as British patent report in 1948, the weak point of this type of method is: entrainer propyl formate, isobutyl formate etc. generally need to be prepared from anhydrous formic acid, simultaneously these The entrainer is easy to be hydrolyzed. During the distillation process, it is hydrolyzed by heat to form formic acid and propanol or butanol, so that the separation cannot continue

As reported in Chinese patent CN1063483 in 1992, the additive thionyl dichloride was used to make it react with formic acid aqueous solution for dehydration, and then vacuum distillation, but because the process is more complicated, it will cause certain pollution to the environment and will bring to higher cost, it is rarely used

Another example is the boric anhydride purification method reported in Chinese literature in 2006, using boric anhydride (boron trioxide) to react with water in dilute formic acid to form boric acid, which can be distilled to obtain high-concentration formic acid, and the remaining boric acid can be reused through drying and dehydration. However, boric acid is dried and dehydrated into boric anhydride, and the temperature needs to be above 300°C, which is difficult to implement industrially, and boric anhydride is expensive, and the production cost is too high

Another example is that U.S. Patent US-A4877490 and US-A4909907 etc. have introduced the method that extraction and rectification obtains high concentration formic acid solution with ethyl benzoate, diethylene glycol methyl ester or benzoic acid acetic anhydride etc. as extraction agent, but because extraction agent price Expensive, and these extractants are high-boiling substances, making it very difficult to recover and reuse, and the extraction effect is not ideal, so these methods are not easy to realize in industry

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