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Highlights • The maximum yield of oil phase organics (OPO) in CFP never exceeded the corresponding oil yield of thermal pyrolysis. • A path forward to obtain higher oil yields is not expected to come from process improvements. • For higher OPO yields, catalysts being able to convert the sugar fraction into OPO are required. Abstract Catalytic pyrolysis of woody biomass and cellulosic materials has been investigated by analyzing the effect of catalysts on aqueous phase (sugar rich) and oil phase (lignin rich) organics produced by the preceding thermal pyrolysis. Tests were done in a downer reactor using ZSM-5 and Na 2 O/γ-Al 2 O 3 as typical commercially available catalysts. Both catalysts converted the aqueous phase organics to coke, water and gas, and deoxygenated and cracked the oil phase organics. The maximum yield of oil phase organics when applying the catalysts never exceeded the corresponding oil yield of thermal pyrolysis (∼22% on carbon basis). Analysis of new results of ex-situ with in-situ catalysis, in combination with earlier reported data, indicates that a path forward to obtain higher oil yields is not expected to come from process improvements. The development of catalysts that can convert the aqueous phase organics (potentially ∼35% on carbon basis) into organic phase ones, instead of cracking and polymerizing them to respectively gas and char, should be considered. [ABSTRACT FROM AUTHOR]

• The effect of recycle gas atmosphere on biomass fast pyrolysis was investigated. • Recycle gas atmosphere did not have a notable effect on the product yields. • Recycle gas atmosphere did not lead to a bio-oil with improved quality. It has been reported that a deoxygenated bio-oil (ca. 0.12 kg kg−1 O on bio-oil basis) can be obtained simply by recycling the non-condensable gases (NCG) of biomass fast pyrolysis to a fluidized-bed reactor operated at atmospheric pressure [Mullen et al., 2013, Energy Fuels, 27, 3867–3874]. Such an unprecedented effect would (i) complicate the use of lab-scale research results obtained typically under inert gas (N 2 , He, Ar) atmosphere for the design of commercial scale pyrolysis units projected to utilize a recycle gas atmosphere (ii) obviate the need for catalytic pyrolysis or mild hydrotreatment processes. Considering these implications, further validation or refutation of the claimed deoxygenation effect of recycle gas atmosphere is needed. Therefore, fast pyrolysis experiments with pine wood were performed in a bench-scale fluidized bed reactor under N 2 atmosphere, recycle gas atmospheres (75 % and 90 % recycle gas volume fraction) at reactor temperatures of 430 °C and 500 °C. Mass balances were obtained and the bio-oils were analyzed using GC/MS, GPC, elemental analysis and Karl Fischer titration. No significant differences were observed in product yield and bio-oil composition (e.g. oxygen content) when going from a nitrogen gas atmosphere to a recycle gas atmosphere for both pyrolysis temperatures. [ABSTRACT FROM AUTHOR]