Biomass pyrolysis toward hydrocarbonization. Influence on subsequent steam gasification processes

Abstract

This work aims to investigate how the carbon densification provided by hydrocarbonization (HTC) of biomass can improve its subsequent exploitation by steam gasification processes, in comparison with traditional pyrolysis. For this task, olive waste was subjected to HTC and pyrolysis. Then the hydrochar (HC) and char (PYR), as well as the pristine precursor (BIO), were steam gasified in a lab-scale experimental installation. The influence of steam flow rate (0.5–1 g min−1) and temperature (700–900 °C) on the composition of the gas evolved (H2, CO, CO2, CH4) was investigated. The results indicated that biomass densification via both pretreatments modifies the gas profiles during gasification, improving H2 and CO production (especially at 900 °C) as well as the heating value. The removal of volatile matter during the pretreatment and greater proportion of fixed carbon can provide a more stable concentration of energetic gases with time, thus improving the overall process from an industrial point of view. The greater effectiveness of HC was demonstrated not only because it allowed recovering a higher amount of the precursoŕs initial energy but also because of the intrinsic cost and environmental advantages of the process.