Preparation method of formamide

Abstract

The invention relates to a preparation method of formamide, belonging to the field of chemical material synthesis. The preparation method comprises the following steps of: ventilating carbon monoxide obtained by treating a tail gas into a reactor; reacting with liquid ammonia under a condition with pressure of 1 MPa-8 MPa under action of an alkaline catalyst, and distilling after the reaction is finished to obtain formamide. The tail gas treatment comprises the following steps of: pressurizing the yellow phosphorus tail gas to 45 KPa-55 KPa through an air blower, removing acid gas in the tail gas by alkali liquor after water-washing, and obtaining carbon monoxide after desulfurization, compression as well as purification treatment; compressing the calcium carbide tail gas to 2.0 MPa-2.1 MPa after removing dust and cooling, thus obtaining carbon monoxide through deoxidation, decarburization and desulfuration. According to the preparation method of the formamide disclosed by the invention, CO in the tail gas is sufficiently utilized, and one-step method production is adopted, so that CO and liquid ammonia can react under low pressure; reaction condition is mild and safe, so that not only is material cost as well as requirements on equipment lowered, but also product yield and product quality are improved.

Description

technical field [0001] The invention relates to a method for preparing formamide, in particular to a method for preparing formamide by reacting liquid ammonia and carbon monoxide purified from tail gas under low pressure conditions, and belongs to the field of chemical material synthesis. Background technique [0002] Carbon monoxide is one of the main air pollutants. It is a highly toxic gas, and 30ppm of carbon monoxide can cause human death. With the development of industry, there are more and more waste gases containing carbon monoxide, such as metallurgical by-product gas, yellow phosphorus furnace gas, calcium carbide furnace gas, carbon black furnace tail gas and incomplete combustion tail gas emitted by various vehicles. As far as the yellow phosphorus and calcium carbide industries are concerned, their emissions cannot be underestimated. According to statistics, the annual output of yellow phosphorus in my country is about 860,000 tons, and the annual output of calc...

AI Technical Summary

Problems solved by technology

[0004] (1) Without any recycling and comprehensive utilization, it is directly discharged into the atmosphere, causing pollution to the environment

[0005] (2) After dedusting, use it as fuel, recycle heat, or burn it directly, which not only has low economic benefits, but also converts carbon dioxide into the atmosphere and forms secondary pollution, which wastes resources and pollutes the environment

[0006] (3) Dust removal, purification, and separation of high-concentration and high-purity carbon monoxide gas for oxo synthesis, development of one-carbon chemical industry, and becoming raw material gas for the production of sodium formate, dimethyl ether and other products, but due to the purity of CO in these production processes High requirements, complex process, large investment, high operating costs, and few mature technologies to choose from, coupled with the small market capacity of these products, thus restricting the development of related industries

However, in the preparation method of this formamide, the reaction not only requires CO with higher purity and concentration as a raw material, but also requires expensive high-pressure equipment, and the product separation process is complicated, which not only increases production costs, but also Does not meet the environmental protection requirements of green chemical process