Supporting Nano Catalysts for the Selective Hydrogenation of Biomass-derived Compounds

The selective hydrogenation of biomass derivatives presents a promising pathway for the production of high-value chemicals and fuels, thereby reducing reliance on traditional petrochemical industries. Recent strides in catalyst nanostructure engineering, achieved through tailored support properties, have significantly enhanced the hydrogenation performance in biomass upgrading. A comprehensive understanding of biomass selective upgrading reactions and the current advancement in supported catalysts is crucial for guiding future processes in renewable biomass. This review aims to summarize the development of supported nanocatalysts for the selective hydrogenation of the US DOE's biomass platform compounds derivatives into valuable upgraded molecules. The discussion includes an exploration of the reaction mechanisms and conditions in catalytic transfer hydrogenation (CTH) and high-pressure hydrogenation. By thoroughly examining the tailoring of supports, such as metal oxide catalysts and porous materials, in nano-supported catalysts, we elucidate the promoting role of nanostructure engineering in biomass hydrogenation. This endeavor seeks to establish a robust theoretical foundation for the fabrication of highly efficient catalysts. Furthermore, the review proposes prospects in the field of biomass utilization and address application bottlenecks and industrial challenges associated with the large-scale utilization of biomass.

Expediting Ethylbenzene Oxidation via a Bimetallic Cobalt-Manganese Spinel Structure with a Modulated Electronic Environment

The catalytic oxidation of ethylbenzene (EB) into acetophenone (AP) is a vibrant area, with a growing number of researchers paying attention to this thematic investigation. Herein, we demonstrate that spinel-type (Co,Mn)(Co,Mn)2O4 can function as an efficient catalyst for the solvent-free oxidation of EB with molecular oxygen. The incorporation of Mn into the Co3O4 network can break the local structural symmetry of Co-O-Co linkages due to the bond competition, inducing the formation of an asymmetrical Co-O-Mn configuration with an electron local exchange interaction. The Co-O-Mn sites can facilitate the perturbation of nonpolar O2 and thus contribute to the generation of abundant •O2- species for initiating the oxidation of EB. We envision that this study not only provides a promising catalyst for EB oxidation but also affords a new insight into the design of advanced spinel oxides for selective oxidation reactions.

Fine-Tuning of Ni/NiO over H-NbOx for Enhanced Eugenol Hydrogenation through Enhanced Oxygen Vacancies and Synergistic Participation of Active Sites

The hydrogenation of lignin-derived phenolics to produce valuable chemicals is a promising but challenging task. This study successfully demonstrates the use of sustainable transition metal-based catalysts to hydrogenate lignin-derived phenolics. A defect-induced oxygen vacancy containing H-NbOx prepared from commercial Nb2O5 was employed as a catalyst. H-NbOx exhibited higher oxygen vacancies (158.21 μmol/g) than commercial Nb2O5 (39.01 μmol/g), evaluated from O2-TPD. Upon supporting 10 wt % Ni, a Ni/NiO interface was formed over H-NbOx, which was intrinsically active for the hydrogenation of phenolics. 10Ni/H-NbOx exhibited a two-fold increase in activity than 10Ni/Nb2O5, achieving >99% eugenol conversion and affording ∼94% 4-propyl cyclohexanol selectivity, wherein ∼63% eugenol conversion and ∼73% 4-propyl cyclohexanol selectivity were obtained over 10Ni/Nb2O5. The Ni/NiO formation was confirmed by X-ray photoelectron spectroscopy, HR-TEM, and H2-TPR analysis, while the oxygen vacancies were verified by Raman spectroscopy and O2-TPD analysis. The resulting interface enhanced the synergy between Ni and H-NbOx and facilitated hydrogen dissociation, confirmed by H2-TPD. Remarkably, 10Ni/H-NbOx maintained its catalytic activity for five tested cycles and demonstrated exceptional activity with various phenolics. Our findings highlight the potential of a sustainable transition metal catalyst for the hydrogenation of lignin-derived phenolic compounds, which could pave the path to producing valuable chemicals in an environmentally friendly manner.

The Role of Copper in the Hydrogenation of Furfural and Levulinic Acid

Currently, there is a great interest in the development of sustainable and green technologies for production of biofuels and chemicals. In this sense, much attention is being paid to lignocellulosic biomass as feedstock, as alternative to fossil-based resources, inasmuch as its fractions can be transformed into value-added chemicals. Two important platform molecules derived from lignocellulosic sugars are furfural and levulinic acid, which can be transformed into a large spectrum of chemicals, by hydrogenation, oxidation, or condensation, with applications as solvents, agrochemicals, fragrances, pharmaceuticals, among others. However, in many cases, noble metal-based catalysts, scarce and expensive, are used. Therefore, an important effort is performed to search the most abundant, readily available, and cheap transition-metal-based catalysts. Among these, copper-based catalysts have been proposed, and the present review deals with the hydrogenation of furfural and levulinic acid, with Cu-based catalysts, into several relevant chemicals: furfuryl alcohol, 2-methylfuran, and cyclopentanone from FUR, and γ-valerolactone and 2-methyltetrahydrofuran from LA. Special emphasis has been placed on catalytic processes used (gas- and liquid-phase, catalytic transfer hydrogenation), under heterogeneous catalysis. Moreover, the effect of addition of other metal to Cu-based catalysts has been considered, as well as the issue related to catalyst stability in reusing studies.

Mild and highly selective hydrogenation of cyclohexyl acetate to cyclohexanol over Cu(i) coordinated amino-functionalized poly(ionic liquid)s

Cu(i) coordinated amino-functionalized poly(ionic liquid)s exhibited an unprecedented performance for mild and highly selective hydrogenation of esters.