Thermal decomposition of Cu(NO3)2·3H2O at reduced pressures

Thermolysis of Cu(NO3)2·3H2O is studied by means of XRD analysis in situ and mass spectral analysis of the gas phase at P=1/10 Pa at low heating rate. It is shown that stage I of the dehydration (40–80 °C) results in the consecutive appearance of crystalline Cu(NO3)2·2.5H2O and Cu(NO3)·H2O. Anhydrous Cu(NO3)2 formed during further dehydration at 80–110 °C is moderately sublimed at 120–150 °C. Dehydration is accompanied by thermohydrolysis, leading to the appearance of Cu2(OH)3NO3 and gaseous H2O, HNO3, NO2, and H2O. The higher pressure in the system, the larger amount of thermohydrolysis products is observed. The formation of the crystalline intermediate CuOx(NO3)y was observed by diffraction methods. Final product of thermolysis (CuO) is formed at 200–250 °C.