(251g) Biomass Fast Pyrolysis Vapor and Bio-Oil Upgrading: Catalyst Deactivation and Its Correlation with Feedstock Properties

Extensive oxygen removal is required to upgrade bio-oils to fuel-range hydrocarbons, while hydrotreating is one of the most common and cost-effective processes already available in existing oil refineries. Long-term operation of the hydrotreater system with raw pyrolysis oil is not feasible because of catalyst fouling and severe reactor bed plugging mainly owing to instability of bio-oil and the fast condensation or polymerization of the active compounds in bio-oil. Therefore, bio-oil quality improvement, especially regarding stability enhancement, is required and still represents the greatest challenge in biomass fast pyrolysis and upgrading technology. The bio-oil stability improvement can be achieved by either vapor phase upgrading (a process called catalytic fast pyrolysis) or liquid phase stabilization by catalytic hydrogenation. Catalysts, especially reduced metal on oxide support, were primarily used in both processes. However, the stability of the upgrading catalyst was the biggest barrier due to the unique qualities of biomass (e.g., high oxygen content, high moisture content, highly reactive functional groups) which causes certain problematic catalyst deactivation. Sensitivity analyses performed for biomass conversion models routinely show that catalyst cost, especially related to catalyst lifetime, has a significant impact on process economics; therefore, improvement in the lifetime of catalyst used will have significant impact on the economic viability of a catalytic process. To this aspect, there is a critical need to develop a correlation of the critical material attributes of fast pyrolysis vapor/oil with upgrading catalyst life to guide the proper select/prioritize of value feedstock and further extend the upgrading catalyst life. This presentation will provide a brief introduction of current fast pyrolysis vapor/oil upgrading process and catalyst, the insight on catalyst deactivation mechanisms, and the establishment of critical material attributes, especially the sulfur content, inorganic content, and foulant/coke precursors in fast pyrolysis vapor/oil, influencing catalyst life.