Pyrolysis of Olive Pomace: Degradation Kinetics, Gaseous Analysis and Char Characterization

The kinetics of olive pomace pyrolysis and the characterization of the obtained products were studied. The thermal degradation characteristics of olive pomace were investigated using thermogravimetric analysis under nitrogen atmosphere. Five heating rate profiles were applied (5, 15, 20, 25 and 30 degrees C.min (-1)), with a final temperature of 600 degrees C which was maintained for 2 h. Two main stages of degradation were identified, corresponding to the degradation of the main compounds (hemicellulose, cellulose and lignin).The kinetic parameters were evaluated by using Kissinger-Akahira-Sunose and parallel reaction methods. The energy of activation was evaluated according to the conversion rate of olive pomace. The analysis of the gaseous products showed that the main pyrolysis gas products of biomass are: CO2 (122.6 mg g(-1)), CO (45.3 mg g(-1)), C3H8 (1.7 mg g(-1)), C3H6 (6 mg g(-1)) and CH4 (20.4 mg g(-1)). The characterization of pyrolytic char was performed using thermogravimetric analysis, BET and X-ray fluorescence (XRF) analyses. The textural properties of the biochar were found to correspond to an ultra-microporous solid with a high porous surface. The BET surface area measured using CO2 adsorption was 296 m(2)g(-1) and the micorpore volume was 0.16 cm(3)g(-1). Furthermore, XRF analysis indicated that Ca and K are the major mineral species in the char with non-negligible presence of P and Mg contents. These different characteristics may encourage its recovery for soil amendment.