Reaction kinetics for hydrothermal liquefaction of Cu-impregnated water hyacinth to bio-oil with product characterization

Abstract

Hydrothermal liquefaction is a promising technology for the conversion of biomass to bio-oil and gaseous fuels. In the present work, isothermal hydrothermal liquefaction experiments of Cu-impregnated water hyacinth were conducted at 280 °C and investigated the effect of reaction time (10 min to 45 min) on bio-oil, carbon hybrids, aqueous products, and gas yields. A short residence time of 15 min was found to be optimum to achieve a maximum total bio-oil yield of 34.82% and analyzed by GC-MS and NMR for identification of compounds. Solid residues were analyzed by FESEM, XPS, XRD, and BET for morphological study, Cu loading, and its transition in the hydrothermal environment. Based on experimental data, reaction kinetics was developed and compared for hydrothermal liquefaction of Cu-impregnated water hyacinth with raw water hyacinth to predict the influence of Cu metal on reaction rate constants during hydrothermal liquefaction. From the kinetic modeling, it was found that the presence of Cu promoted the biomass conversion to bio-oil with light oil to heavy oil ((k4) 0.24404 min−1) conversion being the dominating reaction path. In contrast to catalytic degradation, the light oil conversion to aqueous phase components with a rate constant of 0.26323 min−1 is the most prevailing step for non-catalytic hydrothermal liquefaction.