Kurt M. Van Allsburg

An extensive dataset consisting of adsorption energies of pernicious impurities present in biomass upgrading processes on common catalysts and support materials has been generated. This work aims to inform catalyst and process development for the conversion of biomass-derived feedstocks to fuels and chemicals. A high-throughput workflow was developed to execute density functional theory calculations for a diverse set of atomic (Al, B, Ca, Cl, Fe, K, Mg, Mn, N, Na, P, S, Si, Zn) and molecular (COS, H₂S, HCl, HCN, K₂O, KCl, NH₃) species on 35 unique surfaces for transition-metal (Ag, Au, Co, Cu, Fe, Ir, Ni, Pd, Pt, Re, Rh, Ru) and metal-oxide (Al₂O₃, MgO, anatase-TiO₂, rutile-TiO₂, ZnO, ZrO₂) catalysts and supports. Approximately 3,000 unique adsorption geometries and corresponding adsorption energies were obtained.

Commercialization of next-generation nanostructured catalysts for biomass conversion is largely limited by the unique challenges associated with their large scale manufacture. In this work, we present the scalable, continuous synthesis of nanostructured Pt/TiO₂ catalysts in a single step via flame-spray pyrolysis (FSP) and demonstrate their utility in the upgrading of biomass vapours via catalytic fast pyrolysis (CFP). Spectroscopic and microscopic characterization of the catalysts prepared via FSP and conventional incipient wetness impregnation (IW) demonstrated that the FSP method enabled scalable production of Pt/TiO₂ with distinct Pt speciation (single atoms, clusters, and nanoparticles) that could be tuned by varying the Pt loading. This compositional control by FSP resulted in catalytic activity for upgrading of pine pyrolysis vapours to aromatics, oxygenates, and alkenes that was comparable to the IW analogues' performance, with the addition of more control over the product slate by modifying the FSP synthesis conditions. Specifically, the FSP-synthesized catalysts exhibited decreased hydrogenation performance and greater selectivity towards partially deoxygenated products, aromatics, (cyclo)alkanes, and (cyclo)alkenes with total hydrocarbon yields similar to IW-synthesized catalysts at equivalent Pt loadings. A preliminary cost analysis comparing the FSP and IW processes identified the major cost drivers, including solvent usage, process gas requirements, and Pt utilization, that can be addressed to improve the economic viability of the FSP synthesis developed herein.

Early‐stage cost evaluation during catalyst development holds the potential to accelerate the commercialization and deployment of advanced catalytic materials for sustainable chemical processes. The modeling and assessment of manufacturing costs as early as the laboratory synthesis scale, for example, focusing on materials costs and synthesis performance metrics, can support the development of an experimental–economic feedback loop that enables rapid insight into cost drivers associated with catalyst synthesis and highlights areas that require focused research and development effort. Ultimately, this feedback loop supports the realization of an economic understanding of the overall synthetic process and highlights opportunities to reduce costs, serving as the foundation for the scale‐up of catalyst manufacturing. Herein, a case study is presented utilizing CatCost, a free and publicly available estimation tool for the evaluation of catalyst manufacturing costs, to perform a cost‐responsive optimization of the synthesis of nickel nanoparticles (Ni NPs). It is demonstrated that reagent substitutions with more cost‐effective analogs, coupled with stoichiometric optimization, afford a 58% reduction in raw materials cost without changing the product yield or properties.

With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C₂ to C₈ volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste–derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM “Fast Track” qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste–derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for “Fast Track.” Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet. Significance To meet the growing demand for sustainable aviation fuels (SAF), conversion pathways are needed that leverage wet waste carbon and meet jet fuel property specifications. Here, we demonstrate SAF production from food waste–derived volatile fatty acids (VFA) by targeting normal paraffins for a near-term path to market and branched isoparaffins to increase the renewable content long term. Combining these distinct paraffin structures was shown to synergistically improve VFA-SAF flash point and viscosity to increase the renewable blend limit to 70%. Life cycle analysis shows the dramatic impact on the carbon footprint if food waste is diverted from landfills to produce VFA-SAF, highlighting the potential to meet jet fuel safety, operability, and environmental goals.

Direct alteration of material structure/function through strain is a growing area of research that has allowed for novel properties of materials to emerge. Tuning material structure can be achieved by controlling an external force imposed on materials and inducing stress-strain responses (i.e., applying dynamic strain). Electroactive thin films are typically deposited on shape or volume tunable elastic substrates, where mechanical loading (i.e., compression or tension) can affect film structure and function through imposed strain. Here, we summarize methods for straining n-type doped titanium dioxide (TiO2) films prepared by a thermal treatment of a pseudo-elastic nickel-titanium alloy (Nitinol). The main purpose of the described methods is to study how strain affects electrocatalytic activities of metal oxide, specifically hydrogen evolution and oxygen evolution reactions. The same system can be adapted to study the effect of strain more broadly. Strain engineering can be applied for optimization of a material function, as well as for design of adjustable, multifunctional (photo)electrocatalytic materials under external stress control.

Significance: A long-standing goal in science seeks to understand and mimic photosynthesis. The water oxidation half-reaction of photosynthesis can be mimicked with bulk metal oxide catalysts, although with only modest efficiencies. Thus, there is immense effort to learn how bulk oxides operate and to identify critical mechanistic principles that can guide the design of improved catalysts. A functional molecular analogue of cobalt oxide water oxidation catalysts, the Co ₄ O ₄ cubane, has provided a plethora of mechanistic information, although its instability in solution has prevented thorough characterization of key catalytic intermediates. We now show that a rigid coordination network greatly stabilizes this Co ₄ O ₄ catalyst by providing a supporting “matrix,” immobilizing and preserving the key reactive intermediate to enable structural and catalytic characterization.