LIQUID HYDROCARBONS FROM CATALYTIC PYROLYSIS OF SEWAGE-SLUDGE LIPID AND CANOLA OIL - EVALUATION OF FUEL PROPERTIES

The physical fuel properties which are routinely used to define fuel quality were measured for the unrefined hydrocarbon liquids produced by the pyrolysis of sewage sludge lipid, a carboxylic acid-rich substrate and canola oil (a triglyceride) over activated alumina at 450 degrees C and atmospheric pressure; comparisons were made with the properties of diesel. The measured properties included cloud point, pour point, specific gravity, viscosity, distillation range, cetane index, flash point, heat of combustion, water and sediment, ash, carbon residue, and elemental analysis. Pyrolysis products were also analyzed by gas chromatography and infrared and C-13 NMR spectroscopy. Specific gravity, viscosity, flash point, ash content, carbon residue, and heating values of both products were well within the ASTM prescribed and/or typical range of diesel fuel. The liquid products from sewage sludge lipid and canola oil pyrolysis had cetane values of 48.9 and 47.5, respectively, both of which are above the ASTM specified minimum limit (40). The cloud points of both liquid products (-3 and -12 degrees C, respectively) were higher than that of diesel fuel. However, removal of the upper 20% distillate lowered the cloud point of both products quite significantly (-23 and -30 degrees C, respectively). The products satisfied the average volatility requirements of diesel fuel except that the front-end temperatures were low (approximate to 60 degrees C) compared to diesel(approximate to 170 degrees C). The carbon, hydrogen, nitrogen, and sulfur contents as well as the infrared and proton-decoupled C-13 NMR spectra of both products were similar to those of diesel fuel. Gas chromatograms of the liquid products showed a uniform concentration across the C6 to C17 mass range, whereas for diesel fuel a distribution across the C10 to C19 mass range is common. These results suggest that the major fractions of these liquid products could be viable diesel fuel substitutes or cetane enhancers.