Microwave vacuum pyrolysis rapidly transforms bamboo into solid biofuel: Predicting fuel performances by response surface methodology

Microwave vacuum pyrolysis presents significant advantages in biochar refining and industrial upgrading. In this study, bamboo charcoal (BC) was produced rapidly by microwave vacuum pyrolysis, the microwave pyrolysis and conventional pyrolysis characteristics of bamboo were compared, and the potential of response surface methodology (RSM) to predict the fuel performances was investigated. The results indicated that microwave pyrolysis significantly reduced the heating time, and also effectively lowered the threshold of thermal decomposition reaction. Besides, as the microwave power and radiation time rose, the fixed carbon, ash, higher heating value, energy density, and fuel ratio of BCs increased, while the yield, H/C, O/C, volatile, and energy yield decreased. The quadratic models have high correlation coefficients for these characteristics, which can be used for the prediction of subsequent BCs production. When the microwave power was 1666 W and the radiation time was 13.3 min, the prepared BC exhibited the highest yield while maintaining a fixed carbon content of over 85%. This research provided a green way for the transformation and upgrading of BCs industry, and also showed that the most cost-effective production strategy can be formulated through RSM.