Evaluation on thermal pyrolysis of biomass straw waste: Focusing aspects of products yields, syngas emissions and solid products characterization

In this study, a systematic and quantitative investigation of the pyrolysis characteristics of biomass was conducted in a fixed-bed tubular reactor, and the influence of pyrolysis temperature on product yields, gas emission characteristics, and syngas compositions as well as physicochemical characterization of resulting solids (i.e., char/ash morphologies, mineral transformations, and elemental compositions) was explored in detail. The pyrolysis experiments were performed under N-2, and the resulting solid characterization was detected by XRD, SEM, and EDX. The results indicated that with increasing the pyrolysis temperature from 400 to 800 degrees C, the gaseous product yields increased from 54.9% to 66.7%, while the solid product yield showed a reverse trend, varying within 27.7%-40.5%. Meanwhile, the volume fraction of H-2 in syngas increased from 7% to 33%, while the CO2 presented an opposite trend, suggesting that high temperature favored H-2 formation and inhibited CO2 formation. On the whole, the CO and CO2 emissions were prior to CH4, H-2, and CnHm in sequence. A large amount of sylvite (KCl), quartz (SiO2), dolomite (CaMg(CO3)(2)), and pyroxene (CaMgSi2O6) in the resulting solids were identified in crystal phases. Higher pyrolysis temperature had a significant influence on solid microstructures, resulting in a relatively higher slagging tendency due to low melting eutectics containing K-rich and Ca-rich minerals.