Method of concentrating gaseous hydrocyanic acid and the use of the method in the manufacture of acrylonitrile

Claim 1

IN THE MANUFACTURE OF ACRYLONITRILE BY THE ADDITIVE COMBINATION OF HYDROCYANIC ACID AND ACETYLENE IN THE PRESENCE OF AN AQUEOUS CUPROUS SALT CATALYST, THE HYDROCYANIC ACID AND ACETHYLENE BEING IN THE FORM OF A GASEOUS MIXTURE, THE MODIFICATION WHICH COMPRISES PASSING, AS STARTING MATERIAL FOR THE HYDROCYANIC ACID, A GASEOUS MIXTURE POOR IN HYDROCYANIC ACID THROUGH WATER AT A LOW TEMPERATURE RANGING FROM ABOUT 0* C. TO ABOUT 20-25* C. TO PRODUE A DILUTE AQUEOUS SOLUTION OF HYDROCYANIC ACID, CONTACTING SAID SOLUTION AT A TEMPERATURE FROM ABOUT 40* TO ABOUT 90* C. WITH A GAS CONTAINING ACETYLENE, SAID GAS BEING THE RECIRCULATED GAS IN THE ABOVE MANUFACTURE OF ACRYLONITRILE, WHICH GAS EXPELS THE HYDROCYANIC ACID FROM THE SOLUTION, AND INTRODUCING ACID THUS OBTAINIED INTO THE AQUEOUS HYDROCYANIC ACID THUS OBTAINED INTO THE AQUEOUS CUPROUS SALT CATALYST.