Catalytic Fast Pyrolysis of White Oak Wood in a Bubbling Fluidized Bed

Catalytic fast pyrolysis was performed on white oak wood using two zeolite-type catalysts as bed material in a bubbling fluidized bed reactor. The two catalysts chosen, on the basis of a previous screening study, were Ca(2+) exchanged Y zeolite and a proprietary beta-zeolite type catalyst (catalyst M) both supplied by UOP. Each catalyst proved effective at partially deoxygenating the oak wood pyrolysis vapors during the initial pyrolysis process and adding aromatic hydrocarbons to the liquid product mixture. However, each incurred a penalty of reduced liquid yield and catalyst deactivation due to coke formation on the catalysts' surfaces. The coking on the Ca-Y zeolite catalyst was relatively less severe because the deoxygenation process followed decarbonylation and decarboxylation reaction pathways more compared to the dehydration and dehydrogenation pathways for catalyst M, although evidence that both catalysts were active for all the reaction mechanisms exists. The severe coking problem on catalyst M on catalyst activity was mitigated by successfully regenerating the catalyst in situ, resulting in effective production of partially deoxygenated pyrolysis oils over extended periods of time and concomitantly improving the C/O ratio of the upgraded pyrolysis oils from 1.8/1 to 5.9/1 at best. However, the severe coking does limit the overall carbon conversation efficiency from biomass to catalytic pyrolysis oil. Nonetheless, this demonstrates the potential of producing partially deoxygenated and stable fuel intermediates by in situ catalytic fast pyrolysis for ready use as refinery fuel blendstock using the bubbling fluidized bed technology.