Optimisation of biomass catalytic depolymerisation conditions by using response surface methodology

The aim of this study is to present the optimum operating conditions for reducing energy consumption in the process of obtaining bio-oil from the mixture of sawdust, waste lubricating oil, lime, and commercial catalyst. In the study where the catalytic pressureless depolymerisation (also called Katalytische Drucklose Verölung - KDV) was applied, the operating conditions were analysed with response surface methodology. According to the analysis of variance results, a mathematical model was obtained for specific product yield (bio-oil amount/energy consumption g kWe-1). Effects of temperature (260°C-290°C), catalyst rate (1-2 wt.%) and reaction time (0.5-1 h) were investigated. The optimum conditions for the three independent variables (temperature, catalyst rate, reaction time) were 279 ± 2°C, 2 wt.% and 0.5 h, respectively. Maximum specific product yield was obtained as 970.17 g kWe-1. While the reaction time was the most effective regarding the amount of bio-oil obtained at 1 kWe energy consumption, the temperature was found to be the least effective. In addition to these, bio-oil obtained under optimum conditions were characterised and compared with standard diesel specifications.