Previously, there has been no research conducted on the compositions of non-polar and polar fractions of bio-oil produced by co-pyrolysis of biomass and plastic as the feeds in relation to the variation of N2 gas carrier flow rate. Corn cobs was used to represent biomass and polypropylene (PP) plastic was used as hydrogen donor in the co-pyrolysis. Co-pyrolysis was conducted in a stirred tank reactor at heating rate of 5oC/min. Bio-oil separated into non-oxygenated (non-polar) fraction and oxygenated (polar) fraction. Non-polar fraction can be further processed as bio-fuel, while the polar fraction can be refined to produce different chemicals. The aim of the present research is to investigate the effect of N2 gas flow and feed composition on the composition of polar and non-polar phases of bio-oil. More gas flow rate reduced the vapor phase residence time in the co-pyrolysis reactor. N2 gas flow rate was varied 400, 500 and 600 mL/min with each flow rate performed in 3 different ratios of biomass-plastic feed compositions, i.e. 0%: 100%, 50%: 50%, and 100%: 0%. The higher N2 gas flow rate resulted in higher bio-oil yield but lower char yield. Co-pyrolysis favored synergistic effect on non-polar phase yield and lower N2 gas flow resulted in more synergistic effect. The maximum non-polar fraction addition from its theoretical fraction in bio-oil was 35%. For non-polar phase of bio-oil, GC-MS analysis shows that alkenes were predominant in light fraction of bio-oil, while H-NMR shows that methyl chain was predominant in bio-oil. For polar phase of bio-oil, GC-MS analysis shows that carboxylic acids were predominant in light fraction of bio-oil, while H-NMR shows that carbohydrates were predominant in bio-oil. To utilize non-polar phase of bio-oil as biodiesel, branching index needs to be reduced about one third to a half and double bonds of alkene content needs to be decreased from the present content of 6-7% mole. Co-pyrolysis allows the reduction of phenolic content in polar phase of bio-oil arising more dominance of carbohydrate in the polar phase of bio-oil.
Keywords: Biomass, Bio-oil, Polypropylene Plastic, Slow Co-Pyrolysis