Abstract Na-propionate (NaC2H5CO2) was synthesized from Na2CO3 dissolved in propionic acid. Its thermal behavior was studied in argon and in air. In both atmospheres, two solid-solid phase transitions occur below 250 °C and are followed by melting near 290 °C. Thermal decomposition begins with release of CO2 attributed to the decomposition of a limited amount of propionyl radicals. Elemental carbon results from this process. This initial reaction is followed by a faster conversion reaction into Na2CO3 with evolution of 3-pentanone, CO2, CO, CH4 and C2H4 as found during pyrolysis in argon. In air, oxidative decomposition takes place with CO2 and H2O as main released gases. The stability of Na-propionate is reduced in air compared to argon atmosphere. The reaction paths are discussed and compared with previously published results on Na-propionate and other propionate metalorganic compounds. The potential of using the low temperature phase transitions of Na-propionate for thermal energy storage (ΔH ≈ 245 J/g) was evaluated by submitting samples to 25 heating/cooling cycles.

中文翻译：

---

丙酸钠热行为和分解的新见解

摘要 由溶解在丙酸中的 Na2CO3 合成丙酸钠 (NaC2H5CO2)。在氩气和空气中研究了它的热行为。在这两种气氛中，在 250 °C 以下发生两次固-固相变，然后在 290 °C 附近熔化。热分解始于 CO2 的释放，这归因于有限数量的丙酰基自由基的分解。该过程产生元素碳。该初始反应之后是更快的转化为 Na2CO3 的反应，如在氩气中热解过程中发现的那样，释放出 3-戊酮、CO2、CO、CH4 和 C2H4。在空气中，以 CO2 和 H2O 为主要释放气体发生氧化分解。与氩气气氛相比，丙酸钠在空气中的稳定性降低。讨论了反应路径，并与之前发表的关于丙酸钠和其他丙酸金属有机化合物的结果进行了比较。通过将样品提交 25 个加热/冷却循环来评估使用丙酸钠的低温相变进行热能储存 (ΔH ≈ 245 J/g) 的潜力。