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Meeting aggressive decarbonization targets set by the International Civil Aviation Organization (ICAO) will require the rapid development of technologies to produce sustainable aviation fuel (SAF). Catalytic fast pyrolysis (CFP) can support these efforts by opening pathways for the conversion of woody biomass into an upgraded biogenic oil that can be further processed to SAF and other fuels. However, the absence of end-to-end experimental data for the process leads to uncertainty in the yield, product quality, costs, and sustainability of the pathway. The research presented here serves to address these needs through a series of integrated experimental campaigns in which real biomass feedstocks are converted to a final SAF product using large bench-scale continuous reactor systems. For these campaigns, the degree of catalytic upgrading during CFP was varied to produce CFP-oils with oxygen contents of 17 and 20 wt% on a dry basis. The CFP-oils were then hydrotreated and distilled into gasoline, diesel, and SAF fractions. Detailed yield and compositional data were obtained for each step of the process to inform technoeconomic and lifecycle analyses, and the fuel properties of the SAF fraction were evaluated to provide first-of-its-kind insight into the quality of the final product. This research reveals opportunities to optimize process carbon efficiency by tuning the degree of catalytic upgrading during the CFP step and highlights routes to produce a high-quality cycloalkane-rich SAF with 85-92% reduction in greenhouse gas emissions compared to fossil-based pathways. [ABSTRACT FROM AUTHOR]

The production of advanced biofuels represents a near-term opportunity to decarbonize the heavy vehicle transportation sector. However, important barriers must be overcome and successful deployment of these technologies will require (i) catalyst and process development to reduce cost and improve carbon utilization and (ii) industry-relevant validation of operability to de-risk scale-up. Herein, we seek to address these challenges for an integrated two-step process involving catalytic fast pyrolysis (CFP) followed by co-hydrotreating of bio-oil with refinery streams. Technoeconomic and lifecycle analysis based on the data presented herein reveal the potential to generate low-carbon transportation fuels and chemical co-products with a modelled selling price of $2.83 gasoline gallon equivalent (2016$) and a 78% reduction in greenhouse gas emissions compared to fossil-based pathways. The feedstock for this research was a blend of 50 wt% loblolly pine and 50 wt% waste forest residues, and the CFP step was performed using an ex situ fixed bed of Pt/TiO2 with co-fed H2 at atmospheric pressure. Compared to previous state-of-technology benchmarks, advancements in catalyst design and synthesis methodology enabled a four-fold reduction in Pt loading and a 400% increase in time on stream without negatively impacting upgrading performance. Additionally, a first-of-its-kind integrated assessment of waste gas adsorption showed near quantitative recovery of acetone and 2-butanone, which collectively represent approximately 5% of the biomass carbon. The valorization of these co-products opens opportunities to support decarbonization of the chemical sector while simultaneously improving the overall process carbon efficiency to >40%. After condensation, the CFP-oil was co-hydrotreated with straight run diesel (10 : 90 vol%) to achieve 95% biogenic carbon incorporation. The oxygen content of the hydrotreated oil was below detection limits, and the diesel fraction exhibited a cetane number and cloud point suitable for a finished fuel. This manuscript concludes by highlighting remaining research needs associated with improving thermal management during catalyst regeneration, mitigating catalyst deactivation due to inorganic deposition, and demonstrating the durability of biomass feeding systems when operated in hydrogen-rich environments. [ABSTRACT FROM AUTHOR]

Transition-metal phosphides (TMPs) are promising materials for biomass conversion processes, where their metal–acid bifunctionality provides active sites for the necessary variety of catalytic reactions (e.g., hydrogenation, hydrogenolysis, decarbonylation, and dehydration). Aiming to understand the catalytic performance of ternary TMP catalysts for the hydrodeoxygenation (HDO) reaction of biomass-derived oxygenates, a synthetic protocol was developed herein to prepare a series of ternary Ni2−xRhxP nanoparticles (NPs), incorporating Rh into a parent Ni2P template. This solution synthesis method allowed for a series of NPs to be prepared having precisely controlled compositions with similar morphology and crystalline structure. Detailed characterization of this series of Ni2−xRhxP (x ≤ 1) NPs revealed that Rh substituted into the parent hexagonal crystal lattice of Ni2P with concomitant expansion of the lattice. The influence of composition on the catalytic performance of silica-supported Ni2−xRhxP (x = 0 to 0.8, and cubic Rh2P) NPs was investigated through the HDO reaction of m-cresol. Whereas Rh2P was more selective for direct deoxygenation relative to Ni2P, increasing concentrations of Rh in Ni2−xRhxP resulted in a decreased selectivity to direct deoxygenation products (i.e., toluene, benzene, xylene), and an associated increased selectivity to hydrogenation products (i.e., methylcyclohexene). Through in situ high energy X-ray diffraction and density functional theory modeling, we identified OH* adsorption energy and surface-P sp-band center as effective descriptors for the observed shift in selectivities across this series of TMPs. Furthermore, the calculated electronic-structure changes were found to exert greater influence over the observed product selectivity than the subtle geometric changes associated with lattice expansion. Identification of this structure–function relationship demonstrates that the controlled synthesis of TMPs enables an understanding of composition-dependent selectivity for the HDO reaction of phenolic molecules and this approach could be extended to other ternary TMP compositions for diverse catalytic applications. [ABSTRACT FROM AUTHOR]