Green coconut fiber thermal behaviour under the presence of a cobalt spinel catalyst

Abstract

With increasing environmental concerns, much effort has been spent in research regarding development ofsustainable processes for production of fuels and chemical products. In this context, hydrothermal liquefaction (HTL)has gained increasing attention, as a possible route for the chemical transformation of organic raw-materials, some sortof biomass, for example, into liquid oils at temperatures usually below 400 °C, under moderate to high pressures (5–25MPa), usually in the presence of a suitable catalyst. In the present work the thermogravimetric (TG) behavior underinert atmosphere of pure green coconut fiber and mixtures thereof with a spinel phase (Fe2CoO4), acting as catalysthas been studied. Spinel samples have been produced at 1,000 °C and different calcination times (3 h, 6 h and 9 h). Bothraw and synthesized materials were characterized through different techniques, such as scanning electron microscopy(SEM), X-ray diffraction (XRD) and Infrared Absorption Spectroscopy (FTIR). According to the TG data, the catalystproduced during a calcination time of 9 h showed a superior behavior regarding the lignin full thermal decomposition,which developed without fixed carbon formation. The results further suggest that the mixing process has a significanteffect over the measured degradation kinetics, as it has a direct influence over the contact between catalyst and fibers.The kinetic modelling applied to the dynamic TG signal allowed a quantitative representation of the experimental data.The global process activation energy and order have proven to be respectively, 85.291 kJ/mol and 0.1227.