Fast pyrolysis of biomass: An experimental study on mechanisms influencing yield and composition of the products

Pyrolysis oil originating from biomass has the potential to replace ‘crude fossil oil’ and to produce fuels and chemicals in a more sustainable way. The favorable perspective of fast pyrolysis as biomass pre-treatment step is directly related to the production of a liquid as main product and the significantly higher density of the oil (~1200 kg/m3) compared to the original biomass (~150 kg/m3). The resulting transportation and storage benefits leads to the concept of small decentralized fast pyrolysis plants for production of oil to be transported to a central processing plant. Despite the large number of studies, the understanding of the chemical reactions and physical processes occurring in the fast pyrolysis process is limited. The same holds for the influence of reaction conditions on the yield and composition of the products. Alleged process requirements to obtain high oil yields are recently challenged in literature, based on experimental evidence. At the moment information to make a reliable science based process design of a pyrolysis unit is lacking. This thesis provides clarification in two areas: First, the initial decomposition reactions in the converting biomass in combination with the transport out of the particles of the decay fragments are studied. Secondly, the homogeneous and heterogeneous reactions of the vapors (including aerosols) are investigated.