Catalyst
deactivation due to coking is a major challenge in the
catalytic fast pyrolysis (CFP) of biomass. Here, a multitechnique
investigation of a technical Al2O3-bound ZSM-5-based
extrudate catalyst, used for the CFP of pine wood and cellulose (at
a reactor temperature of 500 °C), provided insight into the effects
of extrusion, the catalytic pyrolysis process, and catalyst regeneration
on the catalyst structure. As a result of a reduction in acidity and
surface area due to the coking catalyst, the activity dropped drastically
with increasing time-on-stream (TOS), as evidenced by a decrease in
aromatics yield. Strikingly, confocal fluorescence microscopy at the
single-particle level revealed that vapor components derived from
whole biomass or just the cellulose component coke differently. While
pine-wood-derived species mainly blocked the external area of the
catalyst particle, larger carbon deposits were formed inside the catalyst’s
micropores with cellulose-derived species. Pyridine FT-IR and solid-state
NMR spectroscopy demonstrated irreversible changes after regeneration,
likely due to partial dealumination. Taken together with <30 g
kg–1 aromatics yield on a feed basis, the results
show a mismatch between biomass pyrolysis vapors and the technical
catalyst used due to a complex interplay of mass transfer limitations
and CFP chemistry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.