Dr. Steven Crossley

Deactivation Studies Associated with Upgrading of Pyrolysis Oils:

The conversion of lignocellulosic biomass to transportation fuels is one of the greatest challenges in catalysis today. A common technique employed is to produce an intermediate product known as pyrolysis oils through the fast pyrolysis of biomass. Pyrolysis oils contain a variety of compounds with a multitude of functional groups and a broad distribution of molecular weights. The optimal catalytic upgrading strategy varies with the functionality and molecular weight of a molecule. For example, it may be desirable to condense light aqueous phase species, such as acetic acid, while larger species such as lignin oligomers would benefit from the opposite strategy of depolymerization and deoxygenation. For this reason, a single upgrading strategy with the entire stream of pyrolysis oil is met with severe challenges. Pyrolysis oil cannot be separated through conventional means of distillation due to the thermal instability. Instead, pyrolysis oil must be separated through either staged upgrading, sequential condensation of the vapors, solubility of various oxygenates in different phases of varying polarity, or size exclusion.

While recent efforts have been made to develop improved fundamental understanding of how individual model compounds present in pyrolysis oils react across specific catalysts, the separation techniques described above are not sufficient to a single compound from the complex mixture known as pyrolysis oil. Instead, a best-case scenario is to provide a stream rich in a specific type of compound, for example rich in acid, furanics, or phenolics. In addition to these complexities, inorganic impurities and char particles present problems for deactivation. Dr. Crossley's project aims to investigate the fundamental role of these impurities present in a species rich on deactivation kinetics as well as the mechanism. This will be accomplished through several catalytic tests in flow reactors combined with detailed post run and in-situ catalyst characterization.

Graphic credit (above):  Center for Biomass Refining