Steam gasification of biochar derived from elephant grass pyrolysis in a screw reactor

Abstract

Steam gasification of biochar has emerged as a promising method for generating bioenergy. In this study was investigated the steam gasification of biochar derived from the elephant grass pyrolysis and evaluated regarding the influence of biochar properties on the steam gasification process. Firstly, elephant grass pyrolysis experiments were performed at 400, 500 and 600 °C in a screw reactor in order to obtain biochar. The biochars were characterized according to FTIR, surface area (BET), and alkali and alkaline earth metals. For biochar produced at 500 °C, steam gasification experiments were conducted at 800, 850, 900 and 950 °C in a fixed-bed reactor, while others biochars were subjected the steam gasification at 900 °C. The maximum reaction rate (dX/dt) of the biochar occurred during the reaction’s initial time (t < 3 min), while at 950 °C the reaction rate rose again during the interval time 12–15 min. Likewise, the H2 maximum reaction rate was observed during the interval between 0 and 3 min (≈4.6 mmolH2/min·gbiochar). Results also show that as gasification temperature (800–950 °C) increased, H2 yield significantly escalated (52.00–82.02 mmol·gbiochar−1), the same was true for dry gas yield (1.54–2.67 N m3·kg−1). In addition, the Arrhenius parameters and the reaction model of the steam gasification of biochar derived from elephant grass have been estimated from some kinetics models available in the literature (VM/GM/RPM).