Fresh ZSM-5 zeolite in the proton form was used for the catalytic pyrolysis of biomass to form spent zeolite, which was then combusted to regenerate the zeolite. Catalytic upgrading of vapors of fast pyrolyzed corn stover over fresh, spent, and regenerated zeolites (referred to as FZ, SZ and RZ, respectively) was carried out using quantitative pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Pre-coking was found to minimize coke yield and favor the formation of target products with higher hydrocarbon and lower oxygen contents. Among all the parameters of the specific surface area, pore volume, and total acid sites (both weak acid sites and strong acid sites), FZ has the highest value, and SZ has the lowest value (FZ > RZ > SZ). The SZ and RZ lowered the total product yields compared to FZ (yield of FZ > RZ > SZ). The coke yields of these zeolites followed the order of FZ > RZ > SZ. Besides, RZ slightly promoted the production of phenols, whereas SZ reduced the relative content of phenols dramatically. (C) 2015 Elsevier B.V. All rights reserved.