The performance of supported metal catalysts can depend on many factors, including metal particle size and dispersion and metal− support interactions, and differentiation of these effects is challenging because of their interwoven relationship. Copper/ceria catalysts are wellknown redox catalysts studied in the conversion of CO and CO 2 via oxidation and/or reduction pathways. The redox behaviors of each species, Cu-CuO and CeO x -CeO 2 , are often suggested to be interlinked, allowing ceria-supported copper domains to outperform copper species on other, nonredox active supports. In this work, the catalytic activity of nanosized Cu supported on either cerium oxide or mesoporous silica is explored using samples where the Cu weight loading, particle size, and dispersion of Cu are held constant to highlight the impact of the two supports on catalytic performance without additional influencing factors. The Cu/CeO 2 catalysts are synthesized via a spaceconfined method to limit the growth of CeO 2 particles and to achieve a high dispersion of Cu. Through in situ XRD and XAS, it is shown that the presence of Cu nanoparticles on the CeO 2 support lowers the reduction temperature of CeO 2 , allowing formation of oxygen vacancies at low temperatures <300 °C. The Cu/CeO x catalyst demonstrates 100% CO selectivity in the low temperature (300 °C) and ambient pressure conversion of CO 2 to CO, even when approaching equilibrium conversion. Moreover, this catalyst is approximately 4 times more active than the corresponding Cu/SiO 2 catalyst with otherwise similar structural attributes. The potential reaction pathways are probed by in situ FTIR and in situ XAS at various temperatures, identifying Cu + -CO species and oxygen vacancies forming under some conditions. The collected experimental evidence also suggests a reaction sequence for CO 2 hydrogenation over Cu/CeO x catalysts, consistent with DFT reports in the literature.

The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-CoAl. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-CoAl catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.

A mesoporous CoAl2O4 spinel (Co‐Al) is synthesized by a one‐step evaporation‐induced self‐assembly (EISA) method. N2 physisorption and TEM are used to demonstrate the presence of mesopores within the Co‐Al material. The spinel crystal structure of Co‐Al, in which Co occupies tetrahedral (Td) sites, is confirmed by using XRD and UV/Vis spectroscopy. In nonoxidative propane dehydrogenation at 550 °C, a propane conversion of approximately 8 % is observed for Co‐Al with a >80 % propylene selectivity, which corresponds to a turnover frequency of 5.1 h−1 based on an estimation of the number of active Co sites by using NH3 temperature‐programmed desorption. A much higher propane conversion rate and a circa 80 % propylene selectivity is observed upon reaction at 600 °C. Continuous deactivation of the catalyst is observed for Co‐Al at this elevated temperature. In situ X‐ray absorption spectroscopy results suggest that Co remains as a Td Co2+ species under the reaction conditions. The Td Co2+ sites within the Co‐Al material are thus proposed to act as Lewis acidic active sites; this acidity is verified using IR spectroscopy with pyridine as a probe molecule.

The ring-opening of furfuryl alcohol to diol products, including 1,2-pentanediol and 1,5-pentanediol, is investigated over reduced Cu–Co–Al mixed metal oxides in a liquid phase batch reactor under H2 pressure. These catalysts are synthesized through the calcination of layered double hydroxides (LDH) to yield well-dispersed, porous mixed metal oxides, which upon reduction displayed activity toward diols, mainly the valuable monomer 1,5-pentanediol. The addition of Cu facilitated the reduction of Co oxide species at lower temperatures, and under optimized conditions, a yield toward 1,5-pentanediol of 44% (total diol yield of 62%) was achieved. Various characterization techniques including temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) are employed to elucidate the structure of the catalysts, suggesting the formation of both metallic (Co and Cu) and oxide (CoO) species after reduction and passivation. Ultimately, this study demonstrates the promising characteristics that nonprecious multimetal catalysts have for the conversion of biomass derived platform molecules to plastic precursors.

The transformation of Co, Cu, and mixed Co/ Cu MOF-74 crystals into bimetallic, carbon-supported Co− Cu catalysts is investigated via high-temperature pyrolysis. Mixed-metal MOFs prepared via a one-step solvothermal synthesis of MOF-74 are transformed into high metal content (48−63 wt %) catalysts by pyrolysis in N 2 at atmospheric pressure and elevated temperatures (300−900 °C). Comprehensive catalysis and structural characterization studies (temperature-programmed reduction, N 2 physisorption, transmission electron microscopy, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, and in situ X-ray absorption spectroscopy) are reported using a range of Co x Cu 1−x (0.33 < x < 0.95) catalyst compositions. The data suggest MOF precursor restructuring occurs to increasingly favor, at higher pyrolysis temperatures, formation of bimetallic nanoparticles with a Co-rich core and Cu-rich shell (Co@Cu core−shell) and suggest a metallic active site in furfural hydrogenation. For differential furfural conversion reactions of the bimetallic catalysts, furfuryl alcohol selectivities between 66 and 89% and 2-methylfuran selectivities of 10−25% are obtained at 180 °C and a W/F of 3.6 g cat /(mol•h) (specific rates of 50− 530 μmol/(g cat •min)). Higher Co:Cu ratios tend to increase activity and shift selectivity toward production of 2-methylfuran. Catalysts formed at elevated pyrolysis temperatures (≥600 °C) display more complete Cu-shells, while at lower pyrolysis temperatures some Co atoms are still present on the nanoparticle surface, resulting in lower furfuryl alcohol selectivity and higher conversion.