Isoconversional kinetic analysis of olive pomace decomposition under torrefaction operating conditions

•Thermal behavior and torrefaction kinetics of olive pomace were studied by TGA.•Model-free kinetic approaches based on isoconversional methods were adopted.•Torrefaction of olive pomace can be adequately described by a single-step model.•Basic linear procedure provides kinetic parameters as accurate as nonlinear one.•Good agreement between experimental and predicted isothermal TG data.

Kinetic analysis of the olive pomace thermal degradation in the temperature range of interest for torrefaction was performed by using non-isothermal thermogravimetric measurements at different heating rates, ranging from 2 to 40 °C/min. A comparison is presented between two selected integral isoconversional methods, i.e., the nonlinear Vyazovkin incremental approach, which is more accurate but time-consuming, and the linear Ozawa–Flynn–Wall (OFW) method, which is less accurate but computationally simpler. Results show that the values of the activation energy by the OFW method are consistent with the ones provided by the Vyazovkin approach. This implies that the OFW method, more user-friendly compared to the Vyazovkin procedure, is suitable for studying the torrefaction kinetics of residual biomass, such as olive pomace. The reliability of the OFW method was further confirmed by the successful application of the derived kinetic data to reproduce (i.e., predict) experimental TG curves not included in the kinetic computations.

Graphical abstractConfigurational and granular temperatures increase with the increase of amplitude and frequency of moveable grates.Figure optionsDownload full-size imageDownload as PowerPoint slide