Bio-fuel production from catalytic fast pyrolysis of Jatropha wastes using pyroprobe GC/MS and drop tube pyrolyzer

Abstract

The effects of temperature and catalytic activity on the decomposition of Jatropha waste to bio-oil under rapid pyrolysis were investigated in this study. The pyrolytic conversion of Jatropha wastes was performed at the temperature range of 400–700 °C. The reactions were conducted and compared between two operations, an analytical pyroprobe GC/MS (µg-scale reactor) and a larger scale, drop tube pyrolyzer. Added catalysts were modified metal (Ce, Co, Ni, and Pd) over activated carbon (Ac) support. In non-catalytic trials, Jatropha wastes pyrolyzed at 600 °C yielded vapor products of mainly oxygenated compounds of acid-ester, aldehyde, and ketone. Addition of Ni/Ac and Pd/Ac catalysts resulted in significantly higher aromatic and total hydrocarbon (aliphatic and cyclic) fractions. The findings suggested that these catalysts are suitable for further investigation with a scaled-up fast pyrolysis sequential process, a drop tube reactor, to convert Jatropha waste into bio‐oil as well as various gaseous and solid byproducts depending on the operating conditions. In this case, the maximum liquid products (bio-oil) yield of 40 wt% was obtained at the reaction temperature of 600 °C and particle size of 0.125–0.425 mm with the presence of Ac. Reaction at 600 °C with Pd/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 revealed the main favorable products as phenols, aromatics, and hydrocarbons which increased almost two folds from base case with Ni/Ac and Pd/Ac addition. Since low oxygenated compounds, high aromatics, and hydrocarbon compounds of bio-oil are desirable, the results indicate that the bio-oil at the optimized condition can be readily applied as biofuel. Moreover, the obtained biochar as a co-product from fast pyrolysis of Jatropha wastes can be used as an alternative solid fuel.