AbstractEx situ catalytic biomass pyrolysis was investigated at both laboratory and bench scale by using a zeolite ZSM‐5‐based catalyst for selectively upgrading the bio‐oil vapors. The catalyst consisted of nanocrystalline ZSM‐5, modified by incorporation of ZrO2 and agglomerated with attapulgite (ZrO2/n‐ZSM‐5‐ATP). Characterization of this material by means of different techniques, including CO2 and NH3 temperature‐programmed desorption (TPD), NMR spectroscopy, UV/Vis microspectroscopy, and fluorescence microscopy, showed that it possessed the right combination of accessibility and acid–base properties for promoting the conversion of the bulky molecules formed by lignocellulose pyrolysis and their subsequent deoxygenation to upgraded liquid organic fractions (bio‐oil). The results obtained at the laboratory scale by varying the catalyst‐to‐biomass ratio (C/B) indicated that the ZrO2/n‐ZSM‐5‐ATP catalyst was more efficient for bio‐oil deoxygenation than the parent zeolite n‐ZSM‐5, producing upgraded bio‐oils with better combinations of mass and energy yields with respect to the oxygen content. The excellent performance of the ZrO2/n‐ZSM‐5‐ATP system was confirmed by working with a continuous bench‐scale plant. The scale‐up of the process, even with different raw biomasses as the feedstock, reaction conditions, and operation modes, was in line with the laboratory‐scale results, leading to deoxygenation degrees of approximately 60 % with energy yields of approximately 70 % with respect to those of the thermal bio‐oil.