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In this work, we provide detailed information on the change in product distribution and bio-oil 12 quality during extended feeding of biomass derived fast pyrolysis vapors over ZSM-5. The effect 13 of catalyst deactivation by coking on the resulting oil product characteristics was clarified in order 14 to determine when the vapor upgrading should be stopped and the regeneration initiated. Obtaining 15 a stable catalytic fast pyrolysis (CFP) oil while maintaining good energy recovery is important 16 within the context of potential co-processing these oils with petroleum feedstocks via FCC or 17 hydrotreatment of the whole CFP oil. 18 Wheat straw derived fast pyrolysis vapors were upgraded in an ex-situ fixed bed reactor containing 19 a steamed ZSM-5 catalyst at 500 °C. Oils were collected both for runs starting the upgrading over 20

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Steam treated HZSM-5 with different Si/Al ratios were tested as catalysts for the upgrading of wheat straw pyrolysis vapors and their performance was compared to hierarchical counterparts, which were prepared by desilication followed by acid washing. Pyrolysis vapors were generated in an ablative system, hot gas filtered, and upgraded in an ex-situ catalyst bed to remove oxygen functionalities and reduce the oils' total acid number (TAN). Besides elemental analysis and TAN, the collected liquids were analyzed for water, chemical composition by gas chromatography mass spectrometry with flame ionization detection (GC-MS/FID), size exclusion chromatography (SEC), thermogravimetric analysis (TGA), and selectively by 1 H nuclear magnetic resonance (NMR), 13 C NMR, and two-dimensional heteronuclear single-quantum correlation (2D HSQC) NMR.Hierarchical and conventional catalysts were analyzed with X-ray fluorescence (XRF), ammonia temperatureprogrammed desorption (NH3-TPD) and ethylamine TPD, N2 and Ar-physisorption, transmission electron microscopy (TEM) and X-ray diffraction (XRD) to investigate changes induced by the desilication process. In addition, samples were analyzed after several reaction and regeneration cycles to investigate catalyst stability. The hierarchical samples showed an increased coking propensity compared to their parent version. The introduction of mesopores after desilication of HZSM-5 with molar Si/Al ratios of 29 and 39 lead to prolonged activity in deoxygenation and improved carbon recovery in the collected oil fractions compared to the parent counterparts.The results indicate that mild deoxygenation may be a viable way of pretreating pyrolysis oil before co-processing with fossil oil in refineries.

19 HZSM-5 extrudates, its two constituents (HZSM-5 zeolite and alumina binder), and SiC for 20 reference were tested after steam treatment for the upgrading of wheat straw fast pyrolysis (FP) 21 vapors from an ablative bench scale system. In addition, mesoporosity was added to the HZSM-5 crystals of the zeolite/Al 2 O 3 extrudates by desilication, which decreased the microporous volume 23 and led to enhanced weak acidity and less strong acidity compared to the parent extrudates. For 24 increasing biomass-to-catalyst ratios (w/w, B:C), oils were collected and analyzed for elemental 25 composition, total acid number (TAN), moisture, molecular weight, evaporation characteristics, 26 and chemical composition by gas chromatography mass spectrometry with flame ionization 27 detection (GC-MS/FID), 1 H nuclear magnetic resonance (NMR), 13 C NMR, and two-dimensional 28 heteronuclear single-quantum correlation (2D HSQC) NMR. Compared to Al 2 O 3 , catalysts 29 containing HZSM-5 promoted aromatization and limited the coke formation due to its shape 30 selective micropores. Nevertheless, Al 2 O 3 was effective in deoxygenation. At B:C ~7, 23 wt-% 31 carbon/25 % energy recovery in the oil fraction was obtained while reducing the oxygen content 32 by 45 % relative to a thermal reference oil fraction obtained over a SiC bed. As such, Al 2 O 3 offers 33 certain benefits compared to HZSM-5 based catalysts due to its lower cost and better hydrothermal 34 stability with respect to acidity. At a catalyst temperature of 500 °C, the introduction of mesopores 35 to HZSM-5 extrudates led to higher energy recovery as oil compared to the parent HZSM-5 36 extrudates. At B:C = 6.3, 23 wt-% carbon/26% energy recovery in the oil phase was achieved 37 while removing 45% of the oxygen functionalities relative to the thermal reference bio-oil.38 Compared to deep deoxygenation for direct hydrocarbon production, mild deoxygenation 39 improved the energy recoveries of the oil fractions and appears viable for pretreating pyrolysis 40 vapors before co-processing bio-oils with fossil oil in refineries.

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Atmospheric hydrodeoxygenation (HDO) of wheat straw fast pyrolysis vapors was studied as a promising route for the production of renewable liquid transportation fuels.

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