Bio-oil Production from Vacuum Pyrolysis of Palm Empty Fruit Bunch: Effect of Operating Conditions and Process Energy Balance

Abstract

This study investigated the effect of temperature, heating rate and particle size on the yields of pyrolysis products from palm empty fruit bunch (EFB). Experiments were carried out in a lab-scale fixed bed pyrolysis system under vacuum condition. Under all conditions studied, the liquid product or known as bio-oil appeared to be dominating. The total liquid (organic + water) yield reached its maximum at 550°C with around two-third being organic and the rest being water. Increasing the particle size generally increased gas yield and decreased liquid yield. However, the catalytic effect of inorganic matters could also have some role during pyrolysis. Higher heating rates increased the yield of organic fraction and overall pyrolysis conversions. The mass and energy balance analysis showed that about two-third of the energy from biomass was concentrated in the liquid product. If not being able to utilize the product char due to the high content of alkalis and only the product gas was used to provide energy for pyrolysis reactions, the net efficiency of the process will largely be affected by the required process energy consumption and the import of external energy may be needed.