Alkali polyphosphates as new potential materials for thermal energy storage

Abstract

Until now, molten salts (nitrate-based salts) are the main materials for sensible heat storage at industrial scale. The working temperature range of these materials is limited below 500°C. There is not yet a solution for sensible heat storage at high temperature. This paper aimed to investigate alkali polyphosphates ((MPO 3) n , with M = Li, Na or K) as new promising materials for sensible heat storage at high temperature. Alkali polyphosphates could be formed by dehydration of monoalkali dihydrogenphosphates (MH 2 PO 4 , with M = Li, Na or K), which occurs below 400°C. Alkali polyphosphates resulted from this dehydration melted at 628, 657 and 812°C for sodium, lithium and potassium polyphosphate, respectively. All these liquids evaporated above 900°C but no destruction of their chemical structure was recorded. Sodium polyphosphate seemed to be the most promising material for sensible heat storage at high temperature because of its large potential working temperature (628-900°C), its availability and its low cost compared to lithium and potassium polyphosphates. The results open new prospects for the development of the thermal energy storage field.

Propiedades físicas y químicas de materiales tipo hidroxiapatita sintetizados a partir de residuos de la industria alimentaria y empleando un método sol-gel modificado

“…Bandas de vibración relativas a grupos fosfato (PO 4 ) 3-, 566, 604, 630, 1032 ≈ 1087, 1092, 1040 cm -1 , y bandas características a grupos carbonato (CO 3 ) 2-, 1480, 1420, and 870 cm -1 , fueron también identificadas. El análisis de los desplazamientos, de cada una de las bandas, permitió identificar que correlacionan con José Galicia Ayala, José Alfredo Díaz, Marvin Chávez-Sifontes espectros de hidroxiapatita tipo B, en que la estructura cristalina muestra sustitución parcial de grupos fosfato por grupos carbonato (Pham Minh et al, 2014).…”