Thermal Decomposition of NaNO3 and KNO3 *

Abstract

Mixtures of sodium nitrate and potassium nitrate have potential applications as high temperature heat transfer fluids and thermal storage media in solar thermal electric power plants. High temperature salt stability is an important characteristic for these applica­ tions; therefore the decomposition of the nitrates was studied to elucidate the mecha­ nisms by which nitrates decompose. To this end, the decomposition of sodium nitrate and potas­ sium nitrate was studied isothermally in vacuum at temperatures ranging from 620-750 K using simultaneous thermogravimetric analysis and mass spectrometry. Decomposition in vacuum was observed as low as 620 K. Nitrogen, nitric oxide, and oxygen were observed to be products of nitrate decomposition.