Volatility of amines used for water treatment in steam generating systems

The relative volatilities of cyclohexylamine and morpholine in dilute aqueous solution have been measured in the temperature range 150 to 300 °C at the corresponding equilibrium vapour pressure of the solution. Cyclohexylamine strongly prefers the steam phase while morpholine has a relatively volatility close to that of water. In both cases an azeotrope of the amine and water, with a vapour pressure higher than that of either component, must exist; however, with morpholine and water azeotrope formation only occurs above 175 °C. The concentration dependence of the distribution between the steam and solution phases of both amines is explained in terms of their partial ionization in solution.