TGA investigation of CO₂ gasification of hydrothermally treated biomass (corn cob-coconut shell mixture)

Gasification is one option for producing cleaner fuel from biomass. A gaseous mixture of H₂, CO, CH₄, and CO₂ is produced through the partial oxidation of biomass with a gasifying agent such as air, pure O₂, steam, CO₂, or a mixture of these. This method is capable of handling a wide range of inhomogeneous biomass (including forest, agricultural, and organic processing residues) and converting them into a homogeneous gas with a considerably higher level of applicability. In this research, the CO2 gasification of hydrothermally treated biomass has been studied using TGDTA analyzer (Bruker TG DTA 2000SA) apparatus. The biomass treated was a mixture of corn cob and coconut shell (weight ratio of 1:1). This raw biomass was firstly subjected to hydrothermal treatment at three different temperatures (200, 240, and 270°C-denoted as H-200, H-240, and H-270) using a batch autoclave prior to being gasified by CO₂ under atmospheric pressure in the TGA apparatus. The experimental results show that the weight loss of hydrochar was resulted mostly from the process of devolatilization (82.92-86.16%). Hydrochar obtained from higher hydrothermal temperatures demonstrated a lower reactivity of gasification, due to the lower amount of moisture and volatile matter. In addition, higher-temperature hydrochar contained lower potassium content and thus shifted the conversion of gasification reaction to a higher temperature.