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Oxidation of renewable polyol/sugar into formic acid using molecular O2 over heterogeneous catalysts is still challenging due to the insufficient activation of both O2 and organic substrates on coordination-saturated metal oxides. In this study, we develop a defective MnO2 catalyst through a coordination number reduction strategy to enhance the aerobic oxidation of various polyols/sugars to formic acid. Compared to common MnO2, the tri-coordinated Mn in the defective MnO2 catalyst displays the electronic reconstruction of surface oxygen charge state and rich surface oxygen vacancies. These oxygen vacancies create more Mnδ+ Lewis acid site together with nearby oxygen as Lewis base sites. This combined structure behaves much like Frustrated Lewis pairs, serving to facilitate the activation of O2, as well as C–C and C–H bonds. As a result, the defective MnO2 catalyst shows high catalytic activity (turnover frequency: 113.5 h−1) and formic acid yield (>80%) comparable to noble metal catalysts for glycerol oxidation. The catalytic system is further extended to the oxidation of other polyols/sugars to formic acid with excellent catalytic performance. This work develops defective MnO2 catalysts with Frustrated Lewis Pairs through a coordination number reduction strategy to enhance the aerobic oxidation of various polyols/sugars to formic acid. [ABSTRACT FROM AUTHOR]

A molecular-level understanding of how the electronic structure of metal center tunes the catalytic behaviors remains a grand challenge in heterogeneous catalysis. Herein, we report an unconventional kinetics strategy for bridging the microscopic metal electronic structure and the macroscopic steady-state rate for CO oxidation over Pt catalysts. X-ray absorption and photoelectron spectroscopy as well as electron paramagnetic resonance investigations unambiguously reveal the tunable Pt electronic structures with well-designed carbon support surface chemistry. Diminishing the electron density of Pt consolidates the CO-assisted O2 dissociation pathway via the O*-O-C*-O intermediate directly observed by isotopic labeling studies and rationalized by density-functional theory calculations. A combined steady-state isotopic transient kinetic and in situ electronic analyses identifies Pt charge as the kinetics indicators by being closely related to the frequency factor, site coverage, and activation energy. Further incorporation of catalyst structural parameters yields a novel model for quantifying the electronic effects and predicting the catalytic performance. These could serve as a benchmark of catalyst design by a comprehensive kinetics study at the molecular level. A molecular-level understanding of the electronic effects remains a grand challenge in heterogeneous catalysis. Here, the authors report an unconventional kinetics strategy for bridging the upscaling gap between the microscopic fingerprints of active sites and the macroscopic catalytic performance. [ABSTRACT FROM AUTHOR]

Catalytic converting the lignin-derived bio-oil to liquid fuel is one promising methodology to reduce the dependence on petroleum-based fuel while easing the atmospheric carbon dioxide burden. Hydrodeoxygenation (HDO) is one commonly used method to convert and upgrade bio-oil from biomass. In the present work, a Ru-promoted MoFeP/Al 2 O 3 catalyst was prepared and evaluated the HDO performance by converting two model compounds, guaiacol and anisole with a batch reactor at 250 °C. This catalyst shows a quite good HDO performance over the two model compounds, in which, oxygen was removed from the phenolic and hydrocarbons were produced as the product. Kinetic studies were also performed to build the reaction network and elucidate the reaction pathway of guaiacol and anisole HDO reactions. The primary, secondary, and tertiary products can be identified for the HDO reactions. A better understanding of HDO chemistry from the fundamental study can lead to more efficient catalysts for the target products. [Display omitted] • A highly active Ru-MoFeP/Al 2 O 3 was proposed in HDO reaction. • Reaction network of guaiacol and anisole HDO reaction were proposed. • Primary product, secondary or tertiary products can be identified. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low H 2 dissociation barrier is obtained using N, S-doped Co single atom catalyst (Co-N 3 SN-def1); • Frustrated Lewis pair comprised of Co and pyridinic N sites facilitate the H 2 dissociation; • H transfer via the solvent water is the main diffusion pathway; • Moderate H adsorption strength at pyridinic N site contributes to the low breaking barrier of N-O bond in nitrobenzene. The limitation of isolated metal active sites in single atom catalysts (SAC) hinder their application in hydrogenation reactions, necessitating the creation of additional active site beyond the metal site. This study introduces pyridinic N and S atoms into the N/C sheet, optimally adjusting the local environment of the Co site. This adjustment synergistically enhances H 2 activation, H diffusion, and promotes the hydrogenation of nitrobenzene into aniline. The sterically hindered Co acidic site and N basic site, known as frustrated Lewis pairs, in defect-containing Co-N 3 SN-def1 model cooperatively facilitate the highly efficient cleavage of the H 2 molecule with a barrier of only 0.37 eV. The findings suggest that the pyridinic N site in the Co-N 3 SN-def1 model acts as a reservoir for *H, significantly contributing to the enhanced activity for the hydrogenation of nitrobenzene. The mechanism unveiled in this study offers valuable insights for designing efficient heterogeneous catalysts for target hydrogenation reactions. [ABSTRACT FROM AUTHOR]

• Microkinetic analysis is used to screen perovskites for methane partial oxidation. • The catalytic activity varies in the order LaMnO 3 > LaFeO 3 > LaCoO 3 ≈ LaCrO 3. • Bulk oxygen vacancy formation energy is identified as a single descriptor. • 667 combinations of A- and B-cations have been screened in terms of stability. • SrRuO 3 , SmRhO 3 , LaIrO 3 , NdRhO 3 , and BaOsO 3 are identified as catalyst candidates. DFT calculations and descriptor-based microkinetic analysis have been performed to screen ABO 3 perovskite catalysts for methane partial oxidation. The scaling relations indicate the adsorption energies of H@O and CH 3 @B have the capability of representing the energetics of methane oxidation, and bulk oxygen vacancy formation energy is identified to be a better single descriptor of the kinetics. The resultant volcano-shaped plot shows the catalytic activity varies in the order LaMnO 3 > LaFeO 3 > LaCoO 3 ≈ LaCrO 3 , which agrees with the experimental findings and thus validates our theoretical predications. By screening 667 combinations of A- and B-cations based on electron neutrality, structural tolerance factors, and experimental verification, 77 ABO 3 have been identified to be stable. Of them, SrRuO 3 , SmRhO 3 , LaIrO 3 , NdRhO 3 , and BaOsO 3 are located at the summit of the volcano, which also exhibit satisfactory CO selectivity and enhanced carbon resistance compared to LaFeO 3 , and may act as the oxygen carrier candidates. [ABSTRACT FROM AUTHOR]

Catalytic conversion of cellulose to diols is an attractive approach in the valorization of biomass, because of the high atom efficiency of the reaction process. The work here highlights the potential of cellulose as a renewable feedstock to produce value-added chemicals, especially vicinal diols. The catalytic conversion of cellulose in water on Ni-Cu/4ZnO-CNT catalyst is discussed, with a focus on four main reaction pathways leading to the formation of C 2 , C 3 , C 4, and C 6 vicinal diols, involving hydrolysis, retro-aldol condensation, hydrogenation, isomerization, dehydrogenation, and thermal side reactions. By modifying the Ni-Cu bimetallic active sites, the pathways can be manipulated, resulting in selective retro-aldol condensation C-C cleavage, leading to a shift towards the selective production of either ethylene glycol (EG) or 1,2-propylene glycol (1,2-PG). Finally, we explore the optimization of reaction conditions to tune product selectivity. This study provides important insight into the catalytic conversion of cellulose and offers promising avenues to produce value-added chemicals from renewable feedstocks. [Display omitted] • Bimetallic NiCu/ZnO-CNT catalyst was proposed in direct cellulose conversion to diols. • Reaction pathway was built based on the kinetic studies. • Product selectivity can be tuned via varying the Ni-to-Cu ratio. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-precious intermetallic compound catalysts for propane dehydrogenation. • Scaling relations are established using formation energies over terraces and steps. • Descriptor-based microkinetic analysis is carried out to obtain volcano curves. • Fe 3 Ga 1 is a good catalyst candidate with improved catalytic performance. By using a descriptor-based microkinetic analysis combined with results from density functional theory calculations over eight transition-metal (including Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) terrace and stepped surfaces, intermetallic compounds have been screened to search for inexpensive and environmentally friendly propane dehydrogenation (PDH) catalysts with enhanced catalytic performance. Based on the scaling relations, the formation energies of ethyl on terrace and methylidyne on stepped surfaces are identified as two descriptors to represent the energetics of other reaction intermediates and transition sates. The derived PDH activity and propylene selectivity volcano curves not only provide a rational interpretation of the previously experimentally reported catalyst candidates, but also predict several unexpected binary combinations by screening 1482 A 3 B 1 and 741 A 1 B 1 intermetallic compounds. The non-precious Fe 3 Ga 1 is then synthesized and evaluated. Its improved propylene selectivity and catalytic stability with respect to those of the Pt catalyst validates the theoretical predictions experimentally. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method to control the surface Mo:C ratio by carbonization flow is discovered for the first time. • The relationship between the surface Mo:C ratio and the reactivity is established. • The low temperature water gas shift reaction activity depends on the electron transfer capability of the surface. • The catalysts with low Mo:C ratio improve catalyst stability. The low-temperature water–gas shift (WGS) reaction is an important industrial process for producing hydrogen and reducing carbon dioxide emissions. The α-MoC 1-x catalysts have shown promising performance in WGS reactions, but their activities are highly dependent on the surface structure. In this study, we investigated the effect of surface Mo and C ordinations on the low-temperature WGS activity of Pt/α-MoC 1-x catalysts using both experimental and theoretical methods. Our results reflected that as Mo: C ratio decreases, the surface free carbon and reduced number of Mo active sites led to a weakened electron transfer ability, resulting in poor catalytic activity. The 0.4% Pt/α-MoC 1-x -50 catalyst displayed superior hydrogen production activity and low apparent activation energy (E app = 58.5 kJ/mol) at low temperatures (100–200 °C). Our density functional theory (DFT) calculations revealed that the high reactivity of the 0.4% Pt/α-MoC 1-x -50 catalyst was due to the strong electron transfer capability and increased number of surface Mo active sites. This study provides new insights into the structure–activity relationship and stability of α-MoC 1-x catalysts for the WGS reaction and lays the foundation for the design of WGS catalysts with high activity and stability at low temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • A transient kinetic model for half-reactions in the redox cycle. • A systematic study for 14 metal chlorides on the CuCl 2 /γ-Al 2 O 3 -based catalysts. • Tuning the redox behavior by affecting the reduction and oxidation steps. • Three types of promoters with different rate-determining steps. • Valuable insights into the reaction process and mechanism. This study investigates the promoter effects of 14 metal chlorides (NaCl, KCl, RbCl, CsCl, MgCl 2 , CaCl 2 , SrCl 2 , CeCl 3 , PrCl 3 , NdCl 3 , ErCl 3 , FeCl 3 , YCl 3 , and SnCl 3) on the CuCl 2 /γ-Al 2 O 3 -based catalysts used for ethylene oxychlorination. The study combines transient experiments of the two half-reactions in the redox cycle to understand the effects of different promoters on the reduction and oxidation rates of the catalysts. The results show that promoter doping can tune the redox behavior of the CuCl 2 /γ-Al 2 O 3 -based catalysts, affecting the reduction and oxidation steps, and the rate-determining step (RDS) changed between reduction and oxidation steps through the effects of different promoters. All the promoters have a positive effect on the reaction rate at steady-state, but the impact of promoter identity on steady-state CuCl 2 concentration is variable and related to the electronegativity of the promoter metal. This work provides a better understanding of the reaction process and mechanism and highlights the potential of promoter doping for improving the efficiency and stability of CuCl 2 / γ -Al 2 O 3 -based catalysts in ethylene oxychlorination. The approach of both transient and steady-state kinetic modeling and simulation is a reliable and efficient method to study promoter effects on reduction–oxidation reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both size and support effects of Au catalysts are explored for MAL conversion. • The Au edge site is identified as the main active site for MMA generation. • A kinetics strategy for disentangling Au geometric and electronic effects is presented. The direct oxidative esterification of methacrolein (MAL) has drawn considerable attention as a promising route to produce methyl methacrylate (MMA). Here, we report a kinetics strategy to identify the active sites of Au catalyst for its disentanglement of geometric and electronic effects on this reaction. A series of Al 2 O 3 and CeO 2 supported Au catalysts are prepared by urea deposition–precipitation method, whose particle sizes are tailored by changing the vacuum-drying temperature. Their catalytic activity is correlated with Au particle size based on a crystal structure modelling, in which the Au edge site is identified as the main active site. The reduction in the valence electron population of Au 5 d states facilitates the adsorption of MAL, thus the positive core-level shift of Au 4f levels for each support gives rise to a higher production of MMA. This kinetics strategy could be extended to the design of other metal catalysts for this reaction. [ABSTRACT FROM AUTHOR]

The activated carbon treated at different temperatures was performed as a catalyst for the oxidation of glycerol to glycolic acid. Heat treatment at suitable temperature could promote the enrichment of ester and carboxyl functional groups with strong electronegativity, which serves as the efficient active site for the glycerol oxidation. Therefore, the optimal AC-400 catalyst with more ester and carboxyl groups shows excellent catalytic activity (0.0039 mol/g Cat /h) and GLYOA selectivity (53.2%). [Display omitted] • The efficient oxidation of glycerol to glycolic acid was realized over heat treated activated carbon. • Heat treatment tuned the composition and electronic structure of oxygen-containing functional groups. • The ester and carboxyl functional groups with strong electronegativity enhanced the adsorption and activation of glycerol. Exploring efficient and cheap catalyst for the selective oxidation of glycerol to valuable carboxylic acids is a critical and complicated challenge. Herein, we innovatively realized the efficient oxidation of glycerol to glycolic acid over metal-free catalyst under mild conditions via carbon material defect engineering. Multiple characterizations revealed that the stepwise functionalization of active carbon caused by simple high temperature control is adopted to fine-tune the composition and electronic structure of oxygen-containing functional groups. Specifically, the abundant ester and carboxyl functional groups exhibit stronger electronegativity than the hydroxyl group, and this enhanced electronic coupling effect strengthens the adsorption of glycerol, thus improving the catalytic activity. Kinetic analysis and density functional theory calculations demonstrated that the oxygen-containing functional groups (mainly ester and carboxyl) could promote the C–H bond activation of RCH 2 O* intermediate and once C–C bond cleavage of glyceric acid, ensuring the high selectivity of glycolic acid (53.2% over AC-400 catalyst). We anticipate that this work could sheds some light on the application and design of more new type of carbon-based metal-free catalysts in the aqueous phase oxidation of various polyols. [ABSTRACT FROM AUTHOR]

[Display omitted] • Substitution of transition metals for Cr increases the acidity of the adjacent O. • Linear scaling relations are established to identify the PDH activity descriptor. • High propylene selectivity of the M 1 -Cr 2 O 3 catalysts is achieved. • Cu 1 -Cr 2 O 3 is predicted to be the best catalyst for PDH among the 13 doped Cr 2 O 3. The catalytic behavior of M 1 -Cr 2 O 3 (M = Mn-Cu, Ru-Ag, and Os-Au) in propane dehydrogenation (PDH) has been studied by employing microkinetic modeling combined with results from periodic DFT + U calculations. Calculated results indicate that most of the single atoms concerned can be stably present on the Cr 2 O 3 surface. The adsorption energy calculations and Bader charge analysis demonstrate that the acidity of the O sites adjacent to the M sites would be enhanced upon doping, which in turn strengthens the atomic H adsorption and the co-adsorption of various PDH species. The surface H formation energy is identified as the reactivity descriptor for PDH over the M 1 -Cr 2 O 3 catalysts, and a volcano curve of the PDH activity is obtained. By calculating the difference between the propylene dehydrogenation and desorption barriers, it is found that some M 1 -Cr 2 O 3 catalysts show improved selectivity towards propylene, as compared to Cr 2 O 3. Comparison between the formation barriers of H 2 and H 2 O reveals that single-atom doping has no apparent negative effect on the catalytic stability of the Cr 2 O 3 surface. The Cu 1 -Cr 2 O 3 catalyst is finally identified as the most promising catalyst for PDH among the 13 M 1 -Cr 2 O 3 catalyst candidates, considering the catalytic activity, selectivity, stability, and cost. [ABSTRACT FROM AUTHOR]