Bio-oil from pyrolysis of Tunisian almond shell: Comparative study and investigation of aging effect during long storage

• Comparative kinetic study of Tunisian almond shell pyrolysis is investigated.
• FTIR, 13CNMR and GC-MS analysis of almond shell bio-oil are performed.
• Aging effect on bio-oil by long storage period is also investigated.
• Almond shell bio-oil can be used as bio-fuel and as resource of bio-chemicals.

Bio-oil from fast pyrolysis of Tunisian almond shell (TN-AS) in fluidized bed reactor was investigated. TG (Thermogravimetric) and DTG (Derivative Thermogravimetric) analyses were performed to quantify the kinetic of its thermal degradation by comparison with other Mediterranean almond shell feedstocks from Spain (SP-AS) and Turkey (TR-AS).The obtained bio-oil was characterized in terms of its composition and energy content using FTIR, 13C NMR and GC-MS. The analyses showed that TN-AS bio-oil was similar to the Turkish one and was slightly different from the Spanish bio-oil.Aging effect at room temperature over a long storage period (5 years) was also investigated to assess bio-oil stability. The aged TN-AS bio-oil had a higher viscosity (705.16 ± 3.76 mm2·s− 1 at 50 °C) while pH, water content and HHV remained unchanged. The increase of viscosity may be due to the increase in the molecular weight resulting of re-polymerization reactions taking place during the long storage period.