CO2 is chosen to substitute N2 as a carrier gas in biomass-polypropylene (PP) pyrolysis due to its abundant availability at low cost and favourable heat emissivity. There has been no research on copyrolysis utilising CO2 gas as sweep gas to bring co-pyrolysis vapour out of the pyrolysis reactor. The objective of the present research is to investigate effect of the use of CO2 as gas carrier on biooil yield in comparison to the use of N2 and on compositions of the resulting non-polar fraction of the bio-oil. Polypropylene composition in the feed was varied 0, 25, 50, 75, and 100 weight %. The co-pyrolysis was conducted in a stirred tank reactor at heating rate of 5oC/min and maximum temperature of 500oC. Yield of non-polar fraction of bio-oil was more dependent to the type of carrier gas than the yield of polar fraction. Synergistic effect on non-polar of bio-oil obtained from copyrolysis in CO2 environment was achieved as the PP composition in feeds more than 40%. H-NMR analysis suggest that in the whole content of non-polar fraction obtained from co-pyrolysis, the compositions of alkenes were low about 6% with the rest mostly alkanes independent of PP composition in feed. However, their branching indices were still about 2.5 times higher than that of diesel fuel advocating the need of adjustment in carbon- chain structure in the non-polar fraction of bio-oil to attain less branching of methyl
Keywords: Co-pyrolysis; Corn cobs; Polypropylene; Carrier Gas; Carbon Dioxide; Bio-oil.