Cu-SSZ-39 zeolite nanosheets-heterogeneous catalyst for the decarboxylative cross-coupling of cinnamic acids with ethers

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Rationally engineering magadiite heavy metal adsorbent for p-nitrophenol hydrogenation reduction

Ανάπτυξη και χαρακτηρισμός καινοτόμων καταλυτών για την αντίδραση μετατόπισης του Co με ατμό (WGS) σε χαμηλές θερμοκρασίες και κινητική μελέτη

In-situ/operando techniques to identify active sites for thermochemical conversion of CO2 over heterogeneous catalysts

Hydrogen reduction is becoming a promising method for recycling lithium-ion battery cathode materials. However, the reaction mechanism and kinetics during hydrogen reduction are unclear, requiring further investigation. Therefore, non-isothermal and isothermal reduction experiments were conducted to evaluate the temperature dependence of the hydrogen reduction kinetics using simultaneous thermogravimetric and differential thermal analysis equipped with mass spectrometry. XRD and SEM were used to characterize the reduction products to understand the underlying reduction mechanisms. The hydrogen reduction profile could be divided into three main stages: decomposition of cathode materials, reduction of the resultant nickel and cobalt oxides, and reduction of LiMnO2 and residual nickel and cobalt oxides. The hydrogen reduction rate increased with increasing temperature, and 800°C was the optimum temperature for separating the magnetic Ni-Co alloy from the non-magnetic manganese oxide particles. The apparent activation energy for the isothermal tests in the range of 500–700°C was 84.86 kJ/mol, and the rate-controlling step was the inward diffusion of H2(g) within each particle. There was an downward progression of the reduction through the material bed for the isothermal tests in the range of 700–900°C, with an apparent activation energy of 51.82 kJ/mol.

Boosted chlorate hydrogenation reduction via continuous atomic hydrogen.

Selective hydrogenation of benzene to cyclohexene over Ru–Zn/ZrO2 catalysts prepared by a two-step impregnation method

Catalytic action of platinum on coke burning

Syngas production over La0.9NiyAl11.95-yO19-δ catalysts during C14-alkane partial oxidation: Effects of sulfur and polycyclic aromatic hydrocarbons

Oxygen availability and catalytic performance of NaWMn/SiO2 mixed oxide and its components in oxidative coupling of methane

Simultaneous excellent catalytic performances toward hydrogenation reduction of 4-nitrophenol and reduction of Cr(VI) in water by novel designing of Cu-CoO/N-doped carbon nanocatalysts

Solid acid materials with tunable structural and acidic properties are promising heterogeneous catalysts for manipulating and/or emulating the activity and selectivity of industrially important catalytic reactions. On the other hand, the performances of acid-catalyzed reactions are mostly dictated by the acidic features, namely, type (Brønsted vs Lewis acidity), amount, strength, and local environment of acid sites. The latter is relevant to their location (intra- vs extracrystalline), and possible confinement and Brønsted-Lewis acid synergy effects that may strongly affect the host-guest interactions, reaction mechanism, and shape selectivity of the catalytic system. This account aims to highlight some important applications of state-of-the-art solid-state NMR (SSNMR) techniques for exploring the structural and acidic properties of solid acid catalysts as well as their catalytic performances and relevant reaction pathway invoked. In addition, density functional theory (DFT) calculations may be exploited in conjunction with experimental SSNMR studies to verify the structure-activity correlations of the catalytic system at a microscopic scale. We describe in this Account the developments and applications of advanced ex situ and/or in situ SSNMR techniques, such as two-dimensional (2D) double-quantum magic-angle spinning (DQ MAS) homonuclear correlation spectroscopy for structural investigation of solid acids as well as study of their acidic properties. Moreover, the energies and electronic structures of the catalysts and detailed catalytic reaction processes, including the identification of reaction species, elucidation of reaction mechanism, and verification of structure-activity correlations, made available by DFT theoretical calculations were also discussed. Relevant discussions will focus primarily on results obtained from our laboratories in the past decade, including (i) quantitative and qualitative acidity characterization utilizing assorted probe molecules, (ii) probing the spatial proximity and synergy effect of acid sites, and (iii) influence of acid features and pore confinement effect on catalytic activity, transition-state stability, reaction pathway, and product selectivity of solid acid catalysts such as zeolites, metal oxides, and heteropolyacids. It is conclusive that a synergy of acidity (local effect) and pore confinement (environmental effect) tend to strongly dictate the formations of intermediates and transition states, hence, the reaction pathways and catalytic performance of solid acid catalysts. We hope that these information can provide additional insights toward our understanding in heterogeneous catalysis, especially the roles of structural and acidic properties on catalytic performances and reaction mechanism of acid-catalyzed systems, which should be beneficial for rational design of solid acid catalysts.

Covalent organic frameworks (COFs) have become a versatile platform to immobilize a wide variety of single‐atom metal catalysts. The resulting post‐synthetic modified materials present a spectrum of valuable properties ranging from homogeneous to heterogeneous systems, such as well‐defined catalytic sites, selectivity, recyclability, and stability. In this minireview, we discuss selected contributions that provide experimental and computational details on reaction mechanisms (e. g., via EXAFS, TEM, and DFT) catalyzed by single‐atom metals embedded within the COF structure. When applicable, we highlight the different behaviour between molecular (homogeneous) and COF‐supported (heterogeneous) sites regarding catalytic performance. With this survey, we aim to decipher the key features that aid in seeing COFs as not merely passive supports but as active items in catalysis.

Iron can be found in all mammalian cells and is of critical significance to diverse cellular activities within human bodies. Widespread applications and the underlying chemical and biological funda...

Effects of reduction on the catalytic performance of limonite ore