This work focuses on the effect of ash during the slow pyrolysis of xylan. To this aim thermogravimetric and pyrolysis reactor tests, up to a temperature of 973 K at a heating rate of 5 K/min, were conducted for two samples: commercial (containing mainly Na and Ca ions) and demineralized xylan. Predictions were obtained with the Bio-PoliMI sub-mechanism of hemicellulose where the catalytic effect of ashes is included. In the case of predictions of the demineralized samples the effect of the ash was not included. Subsequently, the experimental and predicted mass loss profiles, product yields and gas composition were compared. The experimental results show that the commercial and demineralized xylan samples exhibit different pyrolytic behaviors that affect both the product yields and the gas phase composition. The kinetic mechanism is able to capture the mass loss profiles but fails to predict the gaseous species release profiles during the pyrolysis process. The predicted final yield of char is in agreement with the measurements, while the gas and bio-oil final yields are under and over predicted, respectively. Finally, the inclusion of the ash catalytic reaction had a marginal impact on the predictions.
A COMBINED KINETIC AND EXPERIMENTAL APPROACH TO STUDY THE EFFECT OF THE ASH ON SLOW PYROLYSIS OF XYLAN
P Giudicianni;V Gargiulo;R Ragucci
2017
Abstract
This work focuses on the effect of ash during the slow pyrolysis of xylan. To this aim thermogravimetric and pyrolysis reactor tests, up to a temperature of 973 K at a heating rate of 5 K/min, were conducted for two samples: commercial (containing mainly Na and Ca ions) and demineralized xylan. Predictions were obtained with the Bio-PoliMI sub-mechanism of hemicellulose where the catalytic effect of ashes is included. In the case of predictions of the demineralized samples the effect of the ash was not included. Subsequently, the experimental and predicted mass loss profiles, product yields and gas composition were compared. The experimental results show that the commercial and demineralized xylan samples exhibit different pyrolytic behaviors that affect both the product yields and the gas phase composition. The kinetic mechanism is able to capture the mass loss profiles but fails to predict the gaseous species release profiles during the pyrolysis process. The predicted final yield of char is in agreement with the measurements, while the gas and bio-oil final yields are under and over predicted, respectively. Finally, the inclusion of the ash catalytic reaction had a marginal impact on the predictions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
