Experimental and kinetic analysis of Bambusa tulda pyrolysis in carbon dioxide and nitrogen atmosphere

Experiments were conducted using a fixed-bed pyrolysis system and a thermo-gravimetric analyzer to investigate the effect of N2 and CO2 atmosphere on thermal degradation, physicochemical, structural, and elemental characteristics of Bambusa tulda and its char. A kinetic study was conducted at four different heating rates to determine the activation energy, pre-exponential factor, and kinetic model. The results indicate significant weight loss during the second stage of pyrolysis, primarily due to the thermal degradation of low molecular weight compounds such as hemicelluloses, cellulose, and a small fraction of lignin. The CO2atmosphere leads to more significant weight loss compared toN2 atmosphere, with an average weight loss of about 80 % under N2 and approximately 95 % under CO2. This difference is likely due to specific gas-phase reactions and the consumption of carbon fuel induced by CO2. Iso-conversional methods determined that the average activation energy of Bambusa tulda in the presence of N2 was 160.05 kJ mol−1, whereas underCO2, it was 105.51 kJ mol−1. The kinetic mechanism of B. Tulda for both the atmosphere was validated using Cardio’s master plots. The data points for activation energy and pre-exponential factors show a strong linear fit across incremental conversion fractions, indicating the presence of the kinetic compensation effect. Biochar produced in CO2 atmosphere (BCC) exhibited larger pores than biochar generated in N2 atmosphere (BCN). BCN has a porous, organized structure, while BCC displays pores with a channel-like structure due to the development of an aromatic structure. The carbon content and calorific value of Bambusa tulda char are noteworthy, with values of 81.23 % and 25.36 MJ kg−1 for N2 atmosphere, and 85.16 % and 29.44 MJ kg−1 for CO2atmosphere, indicating its potential as feedstock for the gasification process or as an alternative to fossil fuels. •Activation energy is estimated using Friedman, FWO, and KAS iso-conversional methods.•Thermal conversion is enhanced in the presence of CO2 compared to the N2 atmosphere.•The pyrolysis medium affects B. tulda thermal degradation and char yield characteristics.•Using CO2 as the reaction atmosphere improved the carbonization process.•Bamboo char has high levels of potassium, magnesium, calcium, and sodium, enhancing its reactivity in co-gasification with coal or petcoke.