Non-oxidative thermal decomposition of oil palm empty fruit bunch pellets: fuel characterisation, thermogravimetric, kinetic, and thermodynamic analyses

The pre-treatment and pelletisation of oil palm empty fruit bunches (OPEFB) can potentially improve its biofuel properties for efficient thermal energy recovery. Therefore, this paper examines the physicochemical, thermal, kinetic, and thermodynamic properties of OPEFB pellets as a potential feedstock for pyrolysis. Physicochemical analysis revealed high proportions of carbon, volatiles, and fixed carbon compared to nitrogen and sulphur. Morphological analysis showed that the pellet microstructure is comprised of a dense network of polymeric fibres, whereas its ash has consistently shaped agglomerated particles with fine-textured surfaces. Thermogravimetric analysis (TGA) revealed the OPEFB pellets experienced significant mass loss (M-L = 72.8-80.4%) and residual mass (R-M = 19.6-27.2%) during thermal decomposition from 30 to 800 degrees C. The DTG plots revealed thermal decomposition occurred in three stages: I (30-150 degrees C), II (150-600 degrees C), and III (600-800 degrees C) due to drying, devolatilization, and char degradation, respectively. Kinetic analysis showed the activation energy,E-a, ranged from 76.87 to 195.78 kJ/mol, while frequency factor,A, was from 4.77 x 10(01)to 1.22 x 10(18) min(-1)for the Flynn-Wall Ozawa and Kissinger-Akahira Sunose models. The highest kinetic parameters were observed at alpha = 0.40, indicating the rate-determining step for OPEFB pellets decomposition under pyrolysis condition occurs at 40% conversion. Thermodynamic analysis showed that thermal decomposition of OPEFB pellets was characterised by the formation of an activated complex, high reactive multiphase first-order reactions, and short reaction times. In conclusion, the results indicate that OPEFB pellets is a potentially suitable feedstock for pyrolysis owing to its excellent fuel properties and environmentally friendly nature.

Automated summary

The pre-treatment and pelletisation of oil palm empty fruit bunches (OPEFB) can improve its biofuel properties, with high carbon, volatiles, and fixed carbon content. Thermal decomposition of OPEFB pellets occurred in three stages, with the rate-determining step observed at 40% conversion.