Thermal decomposition paths of calcium nitrate tetrahydrate and calcium nitrite

Thermal decomposition processes of calcium nitrate tetrahydrate and calcium nitrite were studied by TG/DSC-FTIR, TG-MS and in-situ DRIFTS. Calcium nitrate tetrahydrate melts at ca. 50 °C and then 1/4, 1/2 and 1/4 of water molecules are released in the range of 50–150 °C, 160–180 °C and 190–220 °C respectively. Calcium nitrate melts at ca. 550 °C and is consecutively decomposed into CaO, O2, NO and NO2, where the ratio of NO to NO2 changes from 2:1 to 1:1 after decomposition maximum point at ca. 580 °C. After melting at ca. 380 °C, calcium nitrite is decomposed into calcium nitrate, CaO and NO first in the range of 470–550 °C, overlapped with the decomposition of calcium nitrate in the range of 550–600 °C. Both decomposition paths are not changed by excess oxygen which only oxidizes part of NO to NO2 in the gas phase.