Chong Liu

A comprehensive periodic DFT study complemented by ab initio thermodynamic analysis was carried out to determine the speciation of extraframework aluminum (EFAl) in faujasite zeolite. The structure and stability of a wide range of mono- bi-, tri-, and tetranuclear EFAl complexes stabilized at different locations in faujasite were investigated. The thermodynamic cycles connecting these complexes were constructed involving such elementary steps as hydration/dehydration, proton transfer, and conden

Operando infrared (IR) spectroscopy and density functional theory (DFT) calculations were combined to investigate the selective catalytic reduction (SCR) of NOx by NH3 over H-AFX zeolites. The steady-state kinetics shows that SCR reactions involving NO2 proceed much more rapidly than those of NO. Data from in situ IR combined with online mass spectrometry under transient conditions demonstrate that Brønsted acid sites (BASs) promote the reaction of NO2 with NH3 to form N2, H2O, and NH4NO3 at low

Zeolites are widely applied as solid acid catalysts in various technological processes. In this work we have computationally investigated how catalytic reactivity scales with acidity for a range of zeolites with different topologies and chemical compositions. We found that straightforward correlations are limited to zeolites with the same topology. The adsorption energies of bases such as carbon monoxide (CO), acetonitrile (CH₃CN), ammonia (NH₃), trimethylamine (N(CH<sub>3<

Chiral diols with three contiguous stereocenters were synthesized by a highly enantioselective ruthenium-catalyzed asymmetric hydrogenation of racemic α,α'-disubstituted cycloketones involving dynamic kinetic resolution. This new catalytic asymmetric method provides a concise route to the alkaloid (+)-γ-lycorane.

A new iridium catalyst containing an imine-diphosphine ligand has been developed, which showed high efficiency for the hydrogenation of CO₂ to formate (yield up to 99%, TON up to 450 000). A possible catalytic mechanism is proposed, in which the imine group of the catalyst plays a key role in the cleavage of H₂ and the activation of CO₂.

Abstract The selective catalytic reduction of NO with ammonia (NH 3 −SCR) catalyzed by Cu−CHA zeolites is thoroughly investigated using in situ spectroscopic experiments combined with on‐line mass spectroscopy (MS) under steady‐state NH 3 −SCR conditions and transient conditions for Cu(II)/Cu(I) redox cycles. Quantitative analysis of the in situ XANES spectra of Cu−CHA under steady‐state conditions of NH 3 −SCR show that NH 3 ‐coordinated Cu(II) species is the dominant Cu species at low temperat

The reaction mechanism of ester hydrogenation catalyzed by a bidentate aminophosphine ligated manganese catalyst was studied by DFT calculations. Particular emphasize was placed on the role of the alkoxide base additives. The presence of such basic promoters as KO t Bu can improve the catalyst activity by lowering the activation barriers of H 2 dissociation as well as the hydrogenation step. The promoting effect of KO t Bu on H 2 activation is much stronger than that of tert-butoxides with other

The alkylation of isobutane with light alkenes plays an essential role in modern petrochemical processes for the production of high-octane gasoline. In this study we have employed periodic DFT calculations combined with microkinetic simulations to investigate the complex reaction mechanism of isobutane-propene alkylation catalyzed by zeolitic solid acids. Particular emphasis was given to addressing the selectivity of the alkylate formation versus alkene formation, which requires a high rate of h

In situ/operando infrared (IR) spectroscopy, kinetics, and density functional theory (DFT) calculations were combined to propose a comprehensive mechanistic model of the selective catalytic reduction (SCR) of the NO/NO2 mixture by NH3, the so-called fast SCR, over Cu-CHA zeolites. Steady-state kinetics for standard and fast SCR over H-CHA and Cu-CHA show that the promotional effect of NO2 on SCR is less significant for Cu-CHA than H-CHA, suggesting that the Brønsted acid site (BAS; H+OZ–) is imp

The mechanism of selective catalytic reduction (SCR) of a NO/NO2 mixture by NH3 (fast SCR) over H–CHA zeolites was revealed by in situ/operando IR spectroscopy and DFT calculations. Kinetic results show that the rate of fast SCR is 2 orders of magnitude higher than that for standard SCR by H–CHA. Combined experimental and computational results show a complete mechanism of fast SCR initiated by the disproportionation of NO2 into adsorbed NO+ and NO3– species. NO+ reacts with NH3 to produce N2 and

An asymmetric hydrogenation of β-branched enol esters has been developed for the first time, providing a new route for the synthesis of β-chiral primary alcohols. Using a (S)-SKP-Rh complex bearing a large bite angle and enol ester substrates possessing an O-fomyl directing group, the desired products were obtained in quantitative yields and with excellent enantioselectivities.

Adsorption is an essential process that takes place in heterogeneous catalysis. In the current study, solid–adsorbate interactions occurring between a variety of small molecules and surfaces of group 13 metal oxides, including β-Ga2O3(100), β-Ga2O3(001), θ-Al2O3(100), θ-Al2O3(001), θ-Al2O3(010), In2O3(110), and In2O3(111), were investigated using density functional theory calculations and a machine learning (ML)-based statistical method. The adsorbates utilized for this purpose include CO, CO2,

DFT calculations suggest that Cu(<sc>i</sc>) oxidation with O₂ as the sole oxidant plays a major role in the oxidation half cycle of standard NH₃-SCR over Cu-CHA zeolites.