Valorization of Sugar Beet Pulp via Torrefaction with a Focus on the Effect of the Preliminary Extraction of Pectins

An agro-industrial residue, i.e., sugar beet pulp, was taken into consideration in this work as a feedstock for valorization as a solid fuel and, potentially, as a source of valuable biochemicals obtainable from the torgas condensable fraction. To this end, an experimental program based on torrefaction of such a residue after pectin extraction (PE-SBP) was performed. The alternative scenario of raw sugar beet pulp (raw-SBP) torrefaction was also investigated for comparison. Raw biomasses and torrefaction products were analyzed by different techniques including thermogravimetric analysis and derivative thermogravimetry (TGA-DTG), Fourier transform infrared spectroscopy (FTIR), gas chromatrography coupled to mass spectrometry (GC/MS), and proximate and ultimate analyses. This allowed the comparative investigation of the role played by the pectin extraction method and the torrefaction temperature on the process performance and main properties of the resulting solid products. Outcomes showed that light torrefaction (200-240 °C) is a suitable and more energy-efficient process for production of high quality solid fuels from SBP. Moreover, it resulted that PE-SBP is better than raw-SBP as a feedstock due to its lower nitrogen and ash content.