A Study on the Comparison of Commercial Coal Coke and Biocoke Derived from Coconut Shell Pyrolysis at Severe Conditions

The increasing demand for clean energy to mitigate air pollutant emissions, together with the need for sustainable carbon-based materials under the circular economy, has driven the exploration of renewable carbon materials derived from lignocellulosic biomass as a renewable bioresource. Due to its abundance, high carbon content, and favorable thermochemical properties, coconut shell was used as a feedstock for producing biocoke at higher pyrolysis temperatures (i.e., 700, 750, 800, and 850 °C) for comparison with commercial coal coke. The pore properties (i.e., surface area and pore volume) and chemical characteristics of commercial coal coke and the resulting biocoke products were characterized. The chemical characterization primarily involved energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR). The findings showed that the pore properties of the biocoke exhibited an upward trend as the pyrolysis temperature increased and were significantly higher than those of commercial coal coke (i.e., 294.37–467.05 m2/g vs. 6.33 m2/g based on the BET surface area). In contrast to the commercial coal coke, the proximate analysis results revealed that the resulting biocoke products possessed higher fixed carbon contents (i.e., 76.94–84.56 wt% vs. 78.40 wt%) and calorific values (i.e., 26.90–33.06 MJ/kg vs. 25.39 MJ/kg). Although the pore properties of Biocoke-700 (produced at 700 °C) were not significantly different from those of the other biocoke products, it appeared to be the optimal sample based on its lower energy consumption, low ash content (i.e., 2.25 wt%), and high fixed carbon content (i.e., 84.56 wt%). Based on the EDS and FTIR analyses, the resulting biocoke products retained moderate oxygen contents (14–18 wt%), implying the presence of oxygen-containing functional groups on the surface. In addition, the biocoke ash mainly contained inorganic compounds such as iron oxides, whereas the coal coke ash primarily consisted of silica and alumina.