A comparative study on valuable products: bio-oil, biochar, non-condensable gases from pyrolysis of agricultural residues

Abstract

In this study, pyrolysis of agricultural residues, such as rice straw (RS), wheat straw (WS), and sugarcane bagasse (SB), was performed in a fixed-bed reactor. The experiments were carried out at varying operating conditions, such as temperature, heating rate, biomass particle size and sweeping gas flow rate, such that the bio-oil yield could be maximized. Small particle size and high heating rate contributed to more bio-oil yield as compared to large particle size and low heating rate. Physicochemical properties of bio-oil samples, evaluated in a comparative manner with maximum focus devoted on analyzing the chemical constituents through GC–MS and FTIR analysis. Biochar was also examined through different physicochemical techniques (e.g., HHV, pH, SEM–EDX, FTIR, CHNS, ICP-AES) for understanding pyrolysis mechanism and its practical usability. Analysis of non-condensable gas through GC-TCD, revealed co-existence of H2, CO, CO2 and CH4 molecules, with greater percentage of H2 and CH4 at high temperature resulted enhancement in calorific value.