Catalytic (mono, bi, and tri-metallic) in-situ hydrothermal liquefaction of water hyacinth

Abstract The hydrothermal liquefaction of mono (Zn), bi-metallic (Fe/Zn, and Cu/Zn), and tri-metallic (Fe/Cu/Zn) impregnated water hyacinth was investigated. The impact of operating parameters like temperature (200-300 °C), residence time (15-45 min), and biomass-to-water ratio (1:3-1:12) was varied to examine the product yields. The Zn-impregnated water hyacinth resulted in a bio-oil yield of 33.2 ± 0.9% and a water-soluble fraction of 45.4 ± 1.4% as Zn has a higher redox reaction with water generating active hydrogens leading to water-soluble organic compounds. The bio-oil samples analyzed by NMR spectroscopy show higher alkanes and alcohol content. FESEM-EDX and TEM analyzed carbon hybrids samples for morphology and an average zinc particle size of 68.6 nm. XRD and XPS analysis confirmed the carbothermal reduction of Zn2+ to zero-valent Zn nanoparticles. The Cu and Fe have been tested to enhance the bio-oil yields and the tri-metallic was the most efficient in enhancing the highest total bio-oil of 37.6 ± 1.1% with the minimum carbon hybrids of 15.6 ± 0.5%.