NREL’s thermochemical biomass conversion research is focused on <i>ex-situ </i>catalytic fast pyrolysis as a potentially efficient and economical route to pyrolysis-based fuel precursors, fuels and chemicals.  In this approach, biomass vapors are generated via fast pyrolysis (FP) and destabilizing vapor components (char, inorganics, tar aerosols) are removed by hot gas filtration with the conditioned vapors more amenable to catalytic upgrading via emerging and industrially available zeolites. We use a Davison circulating riser (DCR), a petroleum industry standard, for CFP while a close coupled pyrolyzer system produces consistent pyrolysis vapors as feed to the DCR. Concurrent upgrading catalyst development is focused on identifying and evaluating modifications to ZSM5-based catalysts that increase carbon content of the condensed product while also reducing catalyst coking and increasing deoxygenation activity. After initial vapor upgrading tests, system modifications that were required to efficiently operate the DCR on vapor feedstocks included adding a cyclone to the stripper outlet to return entrained catalyst to the system, adding a total carbon detector to quantify carbon content of both feed vapor and product gas to simplify carbon mass balances, and optimizing catalyst steam stripping to efficiently recover product.  Subsequent catalyst screening for vapor upgrading showed marked differences in product composition with catalyst type while similar liquid product was obtained with both mixed hardwood and clean pine feedstocks using the same catalyst and process conditions.  The work presented here will show 1) the impact on product composition from pure vapor CFP with a suite of catalysts comprising unmodified, and P- and metal-modified zeolites, and 2) the impact on catalyst coking.<br/>

Catalyst considerations for upgrading biomass pyrolysis vapors and liquids to fungible hydrocarbon intermediates

2019 Spring National Meeting

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