Hydrogen spillover enabled active Cu sites for methanol synthesis from CO2 hydrogenation over Pd doped CuZn catalysts

Catalytic Transfer Hydrogenation of Biomass-Derived Substrates to Value-Added Chemicals on Dual-Function Catalysts: Opportunities and Challenges

Aqueous-phase hydrodeoxygenation (APH) of bioderived feedstocks into useful chemical building blocks is one the most important processes for biomass conversion. However, several technological challenges, such as elevated reaction temperature (220-280 °C), high H₂ pressure (4-10 MPa), uncontrollable side reactions, and intensive capital investment, have resulted in a bottleneck for the further development of existing APH processes. Catalytic transfer hydrogenation (CTH) under much milder conditions with non-fossil-based H₂ has attracted extensive interest as a result of several advantageous features, including high atom efficiency (≈100 %), low energy intensity, and green H₂ obtained from renewable sources. Typically, CTH can be categorized as internal H₂ transfer (sacrificing small amounts of feedstocks for H₂ generation) and external H₂ transfer from H₂ donors (e.g., alcohols, formic acid). Although the last decade has witnessed a few successful applications of conventional APH technologies, CTH is still relatively new for biomass conversion. Very limited attempts have been made in both academia and industry. Understanding the fundamentals for precise control of catalyst structures is key for tunable dual functionality to combine simultaneous H₂ generation and hydrogenation. Therefore, this Review focuses on the rational design of dual-functionalized catalysts for synchronous H₂ generation and hydrogenation of bio-feedstocks into value-added chemicals through CTH technologies. Most recent studies, published from 2015 to 2018, on the transformation of selected model compounds, including glycerol, xylitol, sorbitol, levulinic acid, hydroxymethylfurfural, furfural, cresol, phenol, and guaiacol, are critically reviewed herein. The relationship between the nanostructures of heterogeneous catalysts and the catalytic activity and selectivity for C-O, C-H, C-C, and O-H bond cleavage are discussed to provide insights into future designs for the atom-economical conversion of biomass into fuels and chemicals.

Cu@ZIF-8 derived inverse ZnO/Cu catalyst with sub-5 nm ZnO for efficient CO2 hydrogenation to methanol

Cu@ZIF-8 derived inverse ZnO/Cu with sub-5 nm ZnO acts as an efficient catalyst for CO₂ hydrogenation to methanol.

Conversion of Carbon Monoxide into Methanol on Alumina-Supported Cobalt Catalyst: Role of the Support and Reaction Mechanism—A Theoretical Study

Density functional theory (DFT) was used to calculate the step-by-step hydrogenation of carbon monoxide (CO) to form methanol over a Co4 cluster/Al2O3 surface. A three-dimensional Co4 tetrahedral structure was selected to explore its interaction with the supporting Al2O3 (104) surface. Co4 chemically reacted with Al2O3 to form a new chemical system. The calculated results show that Al2O3 support has strengthened the Co4 catalyst during the reaction since the formation of the Co–O bond. Loading Co4 on the Al2O3 surface increases CO adsorption ability but decreases the dissociation ability of C–O to produce hydrocarbons. As such, CH3OH formation becomes more favorable both kinetically and thermodynamically on Co4/Al2O3. In CO hydrogenation, methanol was synthesized through a CO reaction with hydrogen via either an Eley–Rideal or Langmuir–Hinshelwood pathway to form the intermediates C*-O-H, H-C*-OH, H2-C*-OH, and finally the hydrogenation of H2-C*-OH to methanol with both hydrogenation steps forming C*-OH and final product as rate-limiting. These results showed that the interaction between Co, Al2O3 and H2 pressure can change the pathway of CO hydrogenation on Co/Al2O3 and it may, therefore, influence distribution of the final products.