Pyrolysis of Jatropha curcas pressed cake for bio-oil production in a fixed-bed system

•The pyrolysis of Jatropha curcas waste in a fixed-bed rig was studied.•Yield, calorific value, water content and acidity of bio-oil were compared.•Empirical correlations for bio-oil yield and specifications were developed.•Optimisation of bio-oil production based on combined specifications was achieved.

This study investigated the effects of pyrolysis parameters on the yield and quality of bio-oil from Jatropha curcas pressed cake. This biomass was pyrolysed in a fixed-bed reactor over a temperature range of 573.15 K to 1073.15 K and a nitrogen linear speed range of 7.8 × 10−5 m/s to 6.7 × 10−2 m/s. The heating rate and biomass grain size were 50 K/min and <2 mm, respectively. The bio-oils were tested for the gross calorific value, water content and acidity. The pyrolysis process was simulated using Thermo-Gravimetric Analysis (TGA) and Differential Scanning Calorimeter (DSC) for mass and energy balances analyses. Empirical correlations between the bio-oil specifications and pyrolysis parameters were developed using linear and nonlinear multiple regression methods for process optimisation. At optimum pyrolysis conditions, above 50% of the waste is converted to bio-oil with less than 30% water content, a gross calorific value of 15.12 MJ/kg and a pH of 6.77.