Comparative analysis of N2 and H2 atmospheres in fast pyrolysis of mixed palm waste: Optimizing deoxygenation and hydrocarbon yield

The utilization of biofuel derived from inexpensive, non-edible oils is a promising alternative to conventional fuels. This study focuses on the use of palm waste (MPW), including Palm Fiber (PF), Empty Fruit Bunch (EFB), and Palm Kernel Shell (PKS), as feedstock for biofuel production through fast pyrolysis. It examines the effects of temperature and gas flow in hydrogen and nitrogen atmospheres, aiming to optimize bio-oil yield, hydrocarbon content, and deoxygenation to produce bio-oil with properties close to conventional fuels, making it more suitable for biofuel applications. Bio-oil samples were characterized using gas chromatography-mass spectrometry (GC-MS) to assess their chemical composition. The results show that although N₂ (36.6%) at the optimum temperature of 600 °C and a flow rate of 300 ml/min can produce a higher liquid yield compared to H₂ (34.1) during fast pyrolysis, fast pyrolysis in H₂ can produce a liquid with a higher hydrocarbon, ester, and alcohol content, and improved deoxygenation. Pyrolysis in a hydrogen environment showed better performance in producing less oxygenated bio-oil with better comparative components. To optimize bio-oil quality, this study employed four indices using the Design Expert Response Surface Methodology (RSM): bio-oil yield, hydrocarbon yield, molecular chains with more than five carbons, and deoxygenation. The optimal conditions for H₂ (473^oC and 500 ml/min) were identified to maximize these indices. The experimental results showed a bio-oil yield of 27.45%, a hydrocarbon yield of 9.21%, 91.39% molecular chains with more than five carbons, and a deoxygenation rate of 69.46%, which aligned well with the predictions from the Central Composite Design (CCD) method.