CO Hydrogenation on Ru Single-Atom Catalyst Encapsulated in Silicalite: a DFT and Microkinetic Modeling Study.

The critical levels of CO emissions reached in the past decade have encouraged researchers into finding techniques to reduce the amount of anthropogenic CO expelled to the atmosphere. One possibility is to capture the produced CO from the source of emission or even from air (i.e.

On the Capabilities of Transition Metal Carbides for Carbon Capture and Utilization Technologies.

The search for cheap and active materials for the capture and activation of CO has led to many efforts aimed at developing new catalysts. In this context, earth-abundant transition metal carbides (TMCs) have emerged as promising candidates, garnering increased attention in recent decades due to their exceptional refractory properties and resistance to sintering, coking, and sulfur poisoning. In this work, we assess the use of Group 5 TMCs (VC, NbC, and TaC) as potential materials for carbon capture and sequestration/utilization technologies by combining experimental characterization techniques, first-principles-based multiscale modeling, vibrational analysis, and catalytic experiments.

Comprehensive Density Functional and Kinetic Monte Carlo Study of CO Hydrogenation on a Well-Defined Ni/CeO Model Catalyst: Role of Eley-Rideal Reactions.

A detailed multiscale study of the mechanism of CO hydrogenation on a well-defined Ni/CeO model catalyst is reported that couples periodic density functional theory (DFT) calculations with kinetic Monte Carlo (kMC) simulations. The study includes an analysis of the role of Eley-Rideal elementary steps for the water formation step, which are usually neglected on the overall picture of the mechanism, catalytic activity, and selectivity. The DFT calculations for the chosen model consisting of a Ni cluster supported on CeO (111) show large enough adsorption energies along with low energy barriers that suggest this catalyst to be a good option for high selective CO methanation.

Structural, electronic, and magnetic properties of Ni nanoparticles supported on the TiC(001) surface.

Metals supported on transition metal carbides are known to exhibit good catalytic activity and selectivity, which is interpreted in terms of electron polarization induced by the support. In the present work we go one step further and investigate the effect that a titanium carbide (TiC) support has on the structural, electronic, and magnetic properties of a series of Ni nanoparticles of increasing size exhibiting a two- or three-dimensional morphology. The obtained results show that three-dimensional nanoparticles are more stable and easier to form than their homologous two-dimensional counterparts.

Assessing the usefulness of transition metal carbides for hydrogenation reactions.

Transition Metal Carbides (TMCs) are proposed as replacements for and expensive late Transition Metals (TMs) as heterogeneous catalysts, often implying hydrogenation reactions or steps. Present density functional theory based calculations support using group IV TMCs and δ-MoC as viable TM alternatives, given the moderate exoergicity and affordable reaction step energy barriers.

Unexpectedly large impact of van der Waals interactions on the description of heterogeneously catalyzed reactions: the water gas shift reaction on Cu(321) as a case example.

The molecular mechanisms of the water gas shift reaction on Cu(321) have been chosen to investigate the effect of dispersion terms on the description of the energy profile and reaction rates. The present study based on periodic DFT calculations shows that including dispersion terms does not change the qualitative picture of the overall reaction, maintaining the rate determining step and the predominant route. However, the effect of dispersion is different for different adsorbates - reactants, intermediates or products - with a clear net effect and with no compensation of errors.

ReaxFF molecular dynamics simulations of CO collisions on an O-preadsorbed silica surface.

A quasiclassical trajectory dynamics study was performed for carbon monoxide collisions over an oxygen preadsorbed β-cristobalite (001) surface. A reactive molecular force field (ReaxFF) was used to model the potential energy surface. The collisions were performed fixing several initial conditions: CO rovibrational states (v = 0-5 and j = 0, 20, 35), collision energies (0.

Theoretical study of the dynamics and kinetics of the O + CS → CO + S chemical laser reaction, where CO shows a very high vibrational excitation.

The dynamics and kinetics of the O((3)P) + CS(X(1)Σ(+)) → CO(X(1)Σ(+)) + S((3)P) chemical laser reaction was studied theoretically in detail for the first time, as a function of collision energy (0.0388-2.0 eV) and rovibrational excitation of CS.

Recombination and chemical energy accommodation coefficients from chemical dynamics simulations: O/O2 mixtures reacting over a β-cristobalite (001) surface.

A microkinetic model is developed to study the reactivity of an O/O(2) gas mixture over a β-cristobalite (001) surface. The thermal rate constants for the relevant elementary processes are either inferred from quasiclassical trajectory calculations or using some statistical approaches, resting on a recently developed interpolated multidimensional potential energy surface based on density functional theory. The kinetic model predicts a large molecular coverage at temperatures lower than 1000 K, in contrary to a large atomic coverage at higher temperatures.