Catalytic upgrading bio-oils from fast pyrolysis of jatropha residue using PY-GC/MS and drop tube pyrolyzer

Abstract

Effects of activity of catalysts on the yield and quality of bio-oil from rapid pyrolysis of Jatropha waste were investigated. Pyrolytic conversion of Jatropha wastes was performed at 400-700°C. The reactions were conducted and compared in two reactors, an analytical pyroprobe GC-MS (µg-scale) and a drop tube pyrolyzer (g-scale). In the catalytic trial using Py-GC/MS, alumina (Al2O3) and activated carbon (Ac) catalysts powder with 5 wt% metal loading (Ni or Pd) exhibited high catalytic activities when compared to those of three other ceramic supporters, ZrO2, TiO2 (rutile), and TiO2 (anatase). Therefore, Al2O3 and Ac catalysts are suitable for further investigation with a scaled up drop tube reactor. The maximum bio-oil of 39.38 wt% was obtained at 600°C and particle size of 0.125-0.425 mm with the presence of Ac. Reaction at 600°C with Ni/Ac catalyst yielded bio-oil with the highest HHV of 29.20 MJ/kg with a pH of 6.78. Analysis of bio-oil by GC/MS reveals the main products as phenols, aromatics, and hydrocarbons which increased from 39 to 50-65% (peak area) with Ni/Ac and Pd/Ac catalysts. Since low oxygenated compounds, high aromatics and hydrocarbon compounds of bio-oil are desirable for the pyrolysis of Jatropha wastes, the results indicate that the bio-oil at the optimize condition can be readily applied as biofuel. Moreover, a CFD based model was developed to estimate the volatiles in terms of tar, light gas and char fraction released during in conversion. Comparison with experimental data yielded % deviation for gas species, liquid and solid in the range of 6.67-28.9%, 0.26-11.26%, and 16.67-24.59%, respectively.