Ionic compounds derived from crude glycerol: Thermal energy storage capability evaluation

Abstract

Ionic liquids (diimidazol-1-ium esters) prepared from wastes, crude glycerol and carboxylic acids are investigated as potential phase change materials (PCM). The ionic liquids (IL) with best thermophysical properties were those with also better production yield (higher than 75%). The chemical composition of those IL was with R1 being (CH3)3CCO, CH3(CH2)14CO or C2H3CO; R2 being BIM+; R3 being BIM+; and X- being 2 Cl‾. Phase change of state (solid-liquid) of this IL was 85 ºC, 264 ºC and 128 ºC, which means potential application in different fields such as domestic hot water, solar cooling and industry, respectively. The measured melting enthalpy 328 kJ/kg, 408 kJ/kg, and 660 kJ/kg is much higher in all cases than the usual found in commercial PCM (100 kJ/kg), therefore, these ILs synthetized in this study are proper candidates to be used as PCM because of the huge amounts of energy that they are able to store and their low cost. Moreover, biobPCM are sustainable materials since its obtaining process is based on oil.

The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER) and CTQ2015-70982-C3-1-R (MINECO/FEDER)). The authors would like to thank the Catalan Government for the quality accreditation given to the research groups GREA (2014 SGR 123), Agricultural Biotechnology (2014 SGR 1296) and DIOPMA (2014 SGR 1543). Dr. Camila Barreneche would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-22886.The research leading to these results has received funding from the European Union’s Seventh Framework Program (FP7/2007–2013) under grant agreement n° PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union’s Horizon 2020 research and innovation program under grant agreement No 657466 (INPATH-TES).