Preparation of formic acid

Background and Overview

Formic acid is the simplest organic acid, a small amount of which exists in ants and bees, so it is also called "formic acid".The molecular formula is HCOOH.It is a colorless, transparent and irritating liquid,which is easily soluble in water,alcohol and ether.With strong acidity and reducibility,it is an important chemical raw material.It is volatile and decomposes when heated.There is a risk of burning in case of high heat.Its steam and air can form an explosive mixture. It will cause explosion when encountering hydrogen peroxide.Toxic. Inhalation will stimulate the lungs and stomach. Inhalation in large quantities will cause death. The maximum allowable concentration in the air is 5ppm.Relative density:1.23 (15 ℃/4 ℃); Freezing point: 8.4 ℃; Flash point: 68.89 ℃; Boiling point: 101 ℃; Self ignition point: 600 ℃; Explosion limit: 18%～57%. During storage, keep away from fire and heat source,and isolate from oxidants, alkalis, strong acids, H porogen and cyanide.During loading and unloading, handle with care and do not put it upside down.Prevent water condensation and package damage. Scattered and leaked materials shall be flushed with water, but protective tools shall be worn during treatment.In case of contact with skin, rinse immediately with plenty of water, and apply ointment when necessary.Send to hospital in case of inhalation poisoning.Carbon monoxide and sodium hydroxide are generally used in formic acid production industry,which are widely used in medicine, leather, printing and dyeing, textile, rubber and pesticide industries. China's main producing areas are in Henan, Shenyang, Jiangxi, Jiangsu, Jinan, Guangxi and other places.The annual export volume is nearly 6000 tons, mainly to Malaysia, Japan and New Zealand. 

1.Preparation

The preparation of formic acid mainly includes traditional process,biological process and carbon dioxide hydrogenation process, among which the so-called traditional process mainly includes sodium formate method,butane liquid phase oxidation method, formamide method, methanol carbonyl synthesis method and methyl formate hydrolysis method; Biological method refers to the process of preparing formic acid by oxidation of glucose under the condition of sufficient oxygen and complete reaction. Although theoretically 1mol glucose can be oxidized to 6mol formic acid, the process is still in the laboratory stage, and it will take some time to realize industrialization.At present, the production of formic acid is still dominated by traditional processes.In 1935, Farlow and Adkins first discovered that with Raney Ni as catalyst,carbon dioxide hydrogenation can produce formic acid (salt).In the 1990s,carbon dioxideAs a carbon source, the process of preparing formic acid (salt) or formic acid ester through reduction reaction has become a hot spot in C1 chemistry research and an important way to utilize carbon dioxide. The reaction equation of carbon dioxide hydrogenation to formic acid is:

2.CO2+H2→HCOOH

It is obviously a green process with 100% atomic economy in theory.To study the reaction, firstly, it has theoretical value on how to activate the thermodynamics stable inert molecule carbon dioxide; Second, the hydrogenation of carbon dioxide to formic acid is also a reaction of inorganic matter to organic matter;Third, it can convert the greenhouse gas carbon dioxide into formic acid and its derivatives with wide applications; Fourthly, formic acid is an important liquid hydrogen storage material, which can convert gaseous hydrogen into liquid hydrogen for storage and transportation.Under certain conditions, formic acid can be decomposed to release hydrogen, thus realizing energy cycle.