| 摘要 |
Accumulation of carbon dioxide and nitrogen formed as secondary products in the continuous production of acrylonitrile from acetylene and HCN in the presence of acid cuprous chloride at elevated temperatures with recycling of unchanged acetylene is prevented by removing these gases from the circulating gas. The reaction gas leaving the reaction tower may be washed in the usual way to remove acrylonitrile, HCN, acetaldehyde, &c., and then freed from CO2 by washing with aqueous alkali and the nitrogen removed by washing the circulating gas with water whereupon the acetylene dissolves and the residual undissolved nitrogen may be removed from the system and the acetylene recovered and recycled. The wash water saturated with acetylene is advantageously used for washing the gases leaving the reaction tower. It is preferred to treat only part of the circulating gas, the proportion depending on the amount of CO2 and N2 in the gas. The purified gas is returned to the reaction tower again after the acetylene consumed has been replaced. In an example acetylene and HCN are reacted and the efficiency of acrylonitrile formation decreases when the circulating gases are not treated by the process of the invention; when 3 per cent of the circulating gas is passed through the nitrogen washing system the efficiency is partially restored and when in addition 10 per cent is passed through the alkali liquor washing system to remove CO2, efficiency is restored to the initial value. Specification 691,248 is referred to. |
