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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]

The kinetics of propane dehydrogenation over single‐Pt‐atom‐doped Ga2O3 catalyst has been examined by combining density functional theory calculations and microkinetic analysis. The doping of Pt not only can improve the selectivity of the Ga2O3 catalyst by hindering the deep dehydrogenation reactions but also helps to achieve a long‐term stability by improving the resistance of Ga2O3 to hydrogen reduction. Microkinetic analysis indicates that upon Pt doping the turnover frequency for propane consumption is increased by a factor of 2.8 under typical operating conditions, as compared to the data on the pristine Ga2O3 surface. The calculated results suggest that the Pt1–Ga2O3 catalyst shows a bifunctional character in this reaction where the Pt–O site brings about dehydrogenation while the Ga–O site is active for desorbing H2, which provides a beautiful explanation for the previous experimental observation that even trace amounts of Pt can dramatically improve the catalytic performance of Ga2O3. [ABSTRACT FROM AUTHOR]

Abstract: Novel catalysts are presented for synthesizing carbon nanofibers (CNF) from ethylene decomposition. The catalysts are derived from hydrotalcite (HT) precursors, which contain high amount of active metal species. The synthesis process has been studied and optimized as a function of various parameters such as hydrogen content, gas space velocity, temperature, and catalyst composition. It was found that the yield, nanostructure, and quality of the CNFs were greatly influenced by these process parameters. The aim of the present article is to report the optimized large scale (128g per gram catalyst) synthesis process of high quality CNFs at relatively low temperatures (<650°C). [Copyright &y& Elsevier]

[Display omitted] Developing efficient heterogeneous catalysts for the aerobic oxidation of C–H bonds using oxygen molecule as an oxidant to produce value–added aryl ketones is a challenging task. In this study, a series of cementite–iron–carbon composites (referred to as Fe–C–T, where T represents the pyrolysis temperature) were synthesized using a metal–organic–framework–mediated sacrificial template strategy. The Fe–C–T composites consist of highly dispersed Fe/(Fe 3 C or Fe 2 O 3) nanoparticles surrounded by graphitic carbon on porous carbon supports. Under mild reaction conditions (1 atm of O 2 pressure, 353 K, 12 h), with tert–butyl hydroperoxide (0.25 equiv.) as the initiator in a green solvent water, the prepared Fe–C–973 achieved a high conversion of 98.4 % for ethylbenzene and a selectivity of 98.7 % for acetophenone. This performance was markedly superior to the comparable Fe–C–873 and Fe–C–1073, as well as the commercially available Fe–based catalysts. Kinetic studies revealed that the catalytic system followed first–order kinetics for the substrate ethylbenzene, and the activation energy over Fe–C–973 was remarkably low of 40.4 kJ/mol. The highly distributed Fe 3 C nanoparticles embedded in the porous carbon framework were identified as the most active sites for the reaction. [ABSTRACT FROM AUTHOR]

Enhanced electrochemical reduction of CO 2 to syngas on CuZnOCNT catalyst. • Copper doping on ZnO shifts the ECR activity towards CO formation closer to the top of the volcano. • The optimal amount of copper is around 20 at% for CO formation from electrochemical reduction of CO 2. • Higher amount of Cu doping leads to metallic Cu segregation, resulting in higher H 2 evolution activity. • The 14Cu86ZnO/CNT catalyst shows best performance in terms of syngas (1:1 ratio) production at -0.9 V, better than Ag foil. Electrochemical CO 2 reduction is a promising method for the production of CO 2 neutral fuels and chemicals from renewable electricity. ZnO supported on CNT is a low-cost electro catalyst that can produce syngas from CO 2 and H 2 O. A rational catalyst design strategy for further improvement of the ZnO/CNT catalyst is to dope with copper to strengthen the binding energy of the CO intermediate, which could improve the activity. In this work, a series of CuZnO/CNT catalysts with intimate Cu and Zn contact and various Cu loadings are prepared. By varying the copper content we show that the synergy of copper and zinc improves the activity for CO formation, and the optimal copper content is 20 at%. On hydrogen evolution, the addition of copper has a two-fold effect. This reaction is enhanced by the reduced ZnO particle size obtained when copper is added, but at similar particle sizes of ZnO, a suppression is observed with increasing copper content as CO evolution is enhanced. Stability tests showed that pure ZnO phase is more stable than metallic copper on ZnO. Compared with polycrystalline silver, the CuZnO/CNT catalysts are more active for syngas formation at a useful CO: H 2 composition. This work demonstrates that the viability of DFT based rational design of electrochemical CO 2 reduction catalyst. By varying CuZnO composition as well as crystallite size, one is able to tune the electrochemical reduction activity towards CO and H 2 , and therefore achieve desired syngas ratio. [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]

Review: recent catalytic applications of heteroatom modified novel carbon materials boh as catalyst and catalyst support [ABSTRACT FROM AUTHOR]