Co-pyrolysis under vacuum of sugar cane bagasse and petroleum residue: Properties of the char and activated char products

Abstract

Vacuum pyrolysis of sugar cane bagasse (5.7% moisture) at 500°C and 8 kPa yielded 19.4% charcoal, 34.2% pyrolytic oil, 27.8% water and light organic compounds and 17.6% gases. High surface area (∼1950 m 2/g) activated carbon was obtained from the chars by steam activation. It was earlier observed that the properties of bagasse-derived pyrolytic oil (biofuel) can be improved by co-pyrolysing the bagasse with petroleum residue. The addition of petroleum residue affects the yields and properties of the pyrolytic char. It was shown by thermogravimetry that the formation of the bagasse char is almost complete when the pyrolysis of the major portion of the petroleum residue occurs. Products from the petroleum residue pyrolysis are deposited on the bagasse char, increasing its yield. According to surface spectroscopic results, the surface of the bagasse char is completely covered when the feedstock concentration of petroleum residue reaches 15%. At this concentration the char yield reaches a maximum (30%). Co-pyrolysis chars yield activated carbon with a lower surface area as compared to bagasse chars. However, since the activated carbons derived from the co-pyrolysis char still have high surface areas and the corresponding pyrolytic oil has good combustion properties, co-pyrolysis of bagasse with petroleum residue might be economically feasible.