Method for preparing formic acid by extraction of phosphorus acid and sodium formate

Abstract

The present invention discloses a method of extracting the phosphoric acid and sodium formate to prepare the formic acid. In the method, the isopropyl ether is used for extracting the wet phosphoric acid; then the extraction solution is added into the reactor and does the acidification reaction with the sodium formate to prepare the formic acid. In the reaction process, the volatility of the isopropyl ether is used; the reaction temperature is controlled below 80 DEG C, so as to control the occurrence of the side reaction and to improve the collection rate and concentration of the formic acid; the food-grade formic acid of 98 percent can be prepared. In addition, the material of the low quality such as the wet phosphoric acid is used as the raw material of preparing the formic acid. The present invention greatly lowers the cost and improves the economic benefit.

Description

technical field [0001] The invention relates to a method for preparing formic acid, in particular to a method for preparing formic acid by extracting phosphoric acid and reacting sodium formate. Background technique [0002] It is known that to prepare formic acid from sodium formate, sulfuric acid, phosphoric acid, superphosphoric acid or polymeric phosphoric acid, phosphorus pentoxide and other acidifying aids can be added to acidify to prepare formic acid. The method for preparing formic acid, these methods have been tested by production practice is practical and effective, wherein, prepare formic acid by acidifying sodium formate with sulfuric acid, the use value of sodium sulfate obtained after acidification is low, and discharge a large amount of carbon dioxide and also seriously pollute the environment, this kind The method is basically eliminated; and the method of acidifying sodium formate with phosphoric acid and polyphosphoric acid to produce formic acid can furth...

AI Technical Summary

Problems solved by technology

[0002] It is known that to prepare formic acid from sodium formate, sulfuric acid, phosphoric acid, superphosphoric acid or polymeric phosphoric acid, phosphorus pentoxide and other acidifying aids can be added to acidify to prepare formic acid. The method for preparing formic acid, these methods have been tested by production practice is practical and effective, wherein, prepare formic acid by acidifying sodium formate with sulfuric acid, the use value of sodium sulfate obtained after acidification is low, and discharge a large amount of carbon dioxide and also seriously pollute the environment, this kind The method is basically eliminated; and the method of acidifying sodium formate with phosphoric acid and polyphosphoric acid to produce formic acid can further produce other phosphates, such as sodium tripolyphosphate and sodium hexametaphosphate, because it can co-produce sodium dihydrogen phosphate with high use value. And the pollution is less, so it can be widely used in industry, but phosphoric acid or polyphosphoric acid as an acidifying agent requires its quality to be high, which greatly increases the manufacturing cost of formic acid

[0003] At the same time, since acidification is an exothermic reaction, and formic acid is easy to decompose under local overheating, producing carbon monoxide and water; if the decomposition temperature is greater than 100°C, formic acid will be oxidized to produce carbon dioxide and water, and the generated water will cause the concentration of formic acid to be low. High-concentration formic acid of more than 95% cannot be obtained; further, sodium carbonate will be produced, which will not only greatly reduce the concentration of formic acid, but also bring about many by-products, a decline in the quality of formic acid and serious problems of three wastes

[0004] Chinese patent 200610200857.3 discloses a method for preparing 95% high-concentration formic acid. It uses a reducing multi-component polymeric phosphoric acid mixture as an acidulant to acidify sodium formate to produce 95% high-concentration formic acid. The principle is to use a polymeric phosphoric acid mixture The high adsorption performance absorbs the moisture in the reaction system, thereby increasing the concentration of formic acid. However, the disadvantage of this process is that the amount of polymerized phosphoric acid mixture used will increase, and it may also absorb a certain amount of formic acid. Although it is said to be able to obtain 95% high Concentration of formic acid, but in the actual production process, it is far from reaching this concentration. In addition, its subsequent treatment process is more complicated than traditional technology