Dr. Güray Yildiz


The ideal process for solid biomass conversion involves the production of liquid fuels and chemicals from solid biomass in a single step at short residence times. Pyrolysis is one of the processes that can be used for this purpose and it may be defined as the direct thermal decomposition of a substance (biomass, waste food, waste plastic, etc.) at elevated temperatures with the complete absence of an oxidizing agent (air or oxygen) in a way that no external oxidation, hydrolysis, combustion or gasification occurs to any appreciable extent. The liquid product of pyrolysis can be named bio-oil. It is a complex mixture of chemicals that contains more than 300 compounds. In order to use the bio-oil as a transportation fuel, it can be upgraded in order to reduce its acidity and viscosity (which is too high to be used in diesel engines). Besides the production of transportation fuels, transformation into chemicals is also an important application of catalytic pyrolysis.

Catalytic pyrolysis aims to develop viable methods to improve the quality of the liquid product. As an ideal process for solid biomass conversion, it involves the production of upgraded liquids in a single step and at short residence times. The objective of catalytic pyrolysis is to produce a bio-oil with increased chemical and physical stability (through a reduction in the oxygen content of the bio-oil), increasing yields of target components within the bio-oil, combining the unstable hydrocarbons to form increased amounts of the organic phase, lowering pyrolysis temperatures, and improving miscibility for co-feeding with existing petrochemical refinery systems. In this way, catalytic pyrolysis produces more hydrocarbon-like oil with lower tar and viscous content (e.g. pyrolytic lignins). With catalytic pyrolysis, cracking of the large molecules into the smaller ones is ensured, and the molecular weight range of the produced bio-oil is narrowed (C5-C12 range).