Structure Sensitivity of CO Conversion over Nickel Metal Nanoparticles Explained by Micro-Kinetics Simulations.

Nickel metal nanoparticles are intensively researched for the catalytic conversion of carbon dioxide. They are commercially explored in the so-called power-to-methane application in which renewably resourced H reacts with CO to produce CH, which is better known as the Sabatier reaction. Previous work has shown that this reaction is structure-sensitive.

Polyoxometalate Ionic Sponge Enabled Dendrite-Free and Highly Stable Lithium Metal Anode.

Metallic lithium batteries are holding great promises for revolutionizing the current energy storage technologies. However, the formation of dendrite-like morphology of lithium deposition caused by uneven distribution of Li might cause severe safety concerns of batteries. In this study, a polyoxometalate (POM) cluster, H PMo V O (PMo V ), is added to the conventional electrolyte that can construct a lithium-rich layer and inhibit the growth of Li dendrites effectively.

The influence of doping amount on the catalytic oxidation of formaldehyde by Mn-CeO mixed oxide catalyst: A combination of DFT and microkinetic study.

Formaldehyde (HCHO) is a major environmental pollutant. The Mn-doped CeO catalyst has good catalytic performance for the oxidation of HCHO. The catalytic activity can be effectively tuned by changing the amount of metal doping.

Dynamic restructuring of supported metal nanoparticles and its implications for structure insensitive catalysis.

Some fundamental concepts of catalysis are not fully explained but are of paramount importance for the development of improved catalysts. An example is the concept of structure insensitive reactions, where surface-normalized activity does not change with catalyst metal particle size. Here we explore this concept and its relation to surface reconstruction on a set of silica-supported Ni metal nanoparticles (mean particle sizes 1-6 nm) by spectroscopically discerning a structure sensitive (CO hydrogenation) from a structure insensitive (ethene hydrogenation) reaction.

Optimized CO Capture of the Zeolitic Imidazolate Framework ZIF-8 Modified by Solvent-Assisted Ligand Exchange.

Zeolitic imidazolate frameworks, like ZIF-8 and related structures, have shown great potential for the capture of carbon dioxide. Modifying their structure by exchanging part of the constituent organic ligands is a proven method for enhancing the capacity to absorb CO. In this work, we performed solvent-assisted ligand exchange (SALE) on nanosized ZIF-8 (nZIF-8) with a series of functionalized imidazole derivatives (exchange percentages, after 24 h): 2-bromoimidazole (19%), 2-chloroimidazole (29%), 2-trifluoromethylbenzimidazole (4%), 2-mercaptobenzimidazole (4%), and 2-nitroimidazole (54%).

Lattice oxygen self-spillover on reducible oxide supported metal cluster: the water-gas shift reaction on Cu/CeO catalyst.

In this work we have tackled one of the most challenging problems in nanocatalysis namely understanding the role of reducible oxide supports in metal catalyzed reactions. As a prototypical example, the very well-studied water gas shift reaction catalyzed by CeO supported Cu nanoclusters is chosen to probe how the reducible oxide support modifies the catalyst structures, catalytically active sites and even the reaction mechanisms. By employing density functional theory calculations in conjunction with a genetic algorithm and molecular dynamics simulations, we have identified an unprecedented spillover of the surface lattice oxygen from the ceria support to the Cu cluster, which is rarely considered previously but may widely exist in oxide supported metal catalysts under realistic conditions.

Atomistic Insights Into the Degradation of Inorganic Halide Perovskite CsPbI: A Reactive Force Field Molecular Dynamics Study.

Halide perovskites make efficient solar cells but suffer from several stability issues. The characterization of these degradation processes is challenging because of the limited spatiotemporal resolution in experiments and the absence of efficient computational methods to study these reactive processes. Here, we present the first reactive force field for molecular dynamics simulations of the phase instability and the defect-induced degradation in CsPbI.

Heteropoly Acid-Based Catalysts for Hydrolytic Depolymerization of Cellulosic Biomass.

Cellulose is the most abundant source of biomass, which can be converted into monosaccharide or other chemical platform molecules for the sustainable production of chemicals and fuels. Acid catalysts can promote hydrolytic degradation of cellulose into valuable platform molecules, which is of great significance in the development of chemicals and biofuels. However, there are still some shortcomings and limitations of the catalysts for the hydrolytic degradation of cellulosic biomass.

Engineering the electronic and strained interface for high activity of PdM@Pt electrocatalysts for oxygen reduction reaction.

Alloyed nanoparticles with core-shell structures provide a favorable model to modulate interfacial interaction and surface structures at the atomic level, which is important for designing electrocatalysts with high activity and durability. Herein, core-shell structured PdM@Pt/C nanoparticles with binary PdM alloy cores (M = Fe, Ni, and Co) and a monolayer Pt shell were successfully synthesized with diverse interfaces. Among these, PdFe@Pt/C exhibited the best oxygen reduction reaction catalytic performance, roughly 5.

Bioorthogonal Tetrazine Carbamate Cleavage by Highly Reactive -Cyclooctene.

The high rate of the 'click-to-release' reaction between an allylic substituted -cyclooctene linker and a tetrazine activator has enabled exceptional control over chemical and biological processes. Here we report the development of a new bioorthogonal cleavage reaction based on -cyclooctene and tetrazine, which allows the use of highly reactive -cyclooctenes, leading to 3 orders of magnitude higher click rates compared to the parent reaction, and 4 to 6 orders higher than other cleavage reactions. In this new pyridazine elimination mechanism, wherein the roles are reversed, a -cyclooctene activator reacts with a tetrazine linker that is substituted with a methylene-linked carbamate, leading to a 1,4-elimination of the carbamate and liberation of a secondary amine.

Understanding carbon dioxide activation and carbon-carbon coupling over nickel.

Carbon dioxide is a desired feedstock for platform molecules, such as carbon monoxide or higher hydrocarbons, from which we will be able to make many different useful, value-added chemicals. Its catalytic hydrogenation over abundant metals requires the amalgamation of theoretical knowledge with materials design. Here we leverage a theoretical understanding of structure sensitivity, along with a library of different supports, to tune the selectivity of methanation in the Power-to-Gas concept over nickel.

A Facile Direct Route to N-(Un)substituted Lactams by Cycloamination of Oxocarboxylic Acids without External Hydrogen.

Lactams are privileged in bioactive natural products and pharmaceutical agents and widely featured in functional materials. This study presents a novel versatile approach to the direct synthesis of lactams from oxocarboxylic acids without catalyst or external hydrogen. The method involves the in situ release of formic acid from formamides induced by water to facilitate efficient cycloamination.

Selective Production of Biobased Phenol from Lignocellulose-Derived Alkylmethoxyphenols.

Lignocellulosic biomass is the only renewable source of carbon for the chemical industry. Alkylmethoxyphenols can be obtained in good yield from woody biomass by reductive fractionation, but these compounds are of limited value for large-scale applications. We present a method to convert lignocellulose-derived alkylmethoxyphenols to phenol that can be easily integrated in the petrochemical industry.

N-formyl-stabilizing quasi-catalytic species afford rapid and selective solvent-free amination of biomass-derived feedstocks.

Nitrogen-containing compounds, especially primary amines, are vital building blocks in nature and industry. Herein, a protocol is developed that shows in situ formed N-formyl quasi-catalytic species afford highly selective synthesis of formamides or amines with controllable levels from a variety of aldehyde- and ketone-derived platform chemical substrates under solvent-free conditions. Up to 99% yields of mono-substituted formamides are obtained in 3 min.

Reversible Restructuring of Silver Particles during Ethylene Epoxidation.

The restructuring of a silver catalyst during ethylene epoxidation under industrially relevant conditions was investigated without and with vinyl chloride (VC) promotion. During non-VC-promoted ethylene epoxidation, the silver particles grow and voids are formed at the surface and in the bulk. Electron tomography highlighted the presence of voids below the Ag surface.

Lignin oxidation with an organic peroxide and subsequent aromatic ring opening.

The oxidation of an organosolv lignin with tert-butylhydroperoxide, initiated by titanium grafted into the lignin structure, was investigated. Titanation of reactive groups on lignin is responsible for the cross-linking of the lignin structure. IR and MAS C NMR spectroscopy spectra confirmed the oxidation of the lignin structure and other pronounced structural changes.

Synthesis of stable and low-CO selective ε-iron carbide Fischer-Tropsch catalysts.

The Fe-catalyzed Fischer-Tropsch (FT) reaction constitutes the core of the coal-to-liquids (CTL) process, which converts coal into liquid fuels. Conventional Fe-based catalysts typically convert 30% of the CO feed to CO in the FT unit. Decreasing the CO release in the FT step will reduce costs and enhance productivity of the overall process.

Structure and Evolution of Confined Carbon Species during Methane Dehydroaromatization over Mo/ZSM-5.

Surface carbon (coke, carbonaceous deposits) is an integral aspect of methane dehydroaromatization catalyzed by Mo/zeolites. We investigated the evolution of surface carbon species from the beginning of the induction period until the complete catalyst deactivation by the pulse reaction technique, TGA, C NMR, TEM, and XPS. Isotope labeling was performed to confirm the catalytic role of confined carbon species during MDA.

Publisher Correction: Structure-performance descriptors and the role of Lewis acidity in the methanol-to-propylene process.

In the version of this Article originally published, on the right side of Fig. 4b, the 'Aromatic cycle' label was erroneously shifted outside of the central circular arrow into a position on part of the reaction cycle. This has been corrected in the online versions of the Article.

Structure-performance descriptors and the role of Lewis acidity in the methanol-to-propylene process.

The combination of well-defined acid sites, shape-selective properties and outstanding stability places zeolites among the most practically relevant heterogeneous catalysts. The development of structure-performance descriptors for processes that they catalyse has been a matter of intense debate, both in industry and academia, and the direct conversion of methanol to olefins is a prototypical system in which various catalytic functions contribute to the overall performance. Propylene selectivity and resistance to coking are the two most important parameters in developing new methanol-to-olefin catalysts.

Influence of Carbon Deposits on the Cobalt-Catalyzed Fischer-Tropsch Reaction: Evidence of a Two-Site Reaction Model.

One of the well-known observations in the Fischer-Tropsch (FT) reaction is that the CH selectivity for cobalt catalysts is always higher than the value expected on the basis of the Anderson-Schulz-Flory (ASF) distribution. Depositing graphitic carbon on a cobalt catalyst strongly suppresses this non-ASF CH, while the formation of higher hydrocarbons is much less affected. Carbon was laid down on the cobalt catalyst via the Boudouard reaction.