Theoretical study on thermal stability of molten salt for solar thermal power

摘要

Molten salt (HTS) composed of 53% KNO_3, 40% NaNO_2 and 7 wt.% NaNO_3 has been used as heat transfer media and thermal storage fluid in the solar thermal power, but thermal decomposition will occur at higher temperature because of the oxidation of nitrite to nitrate in the air. In this paper, the reaction mechanism of NO_2~- oxidation is researched by quantum mechanical method. The results show that two components of the transition state (O_2NO_2~-) and intermediate ([NO_4~-]) are found in the reaction. This reaction is an exothermic reaction and the activation barrier is 94.0 kJ mol~(-1). The energy difference of this reaction is very large, so the reaction rate is very slow.