Going Beyond Silver in Ethylene Epoxidation with First-Principles Catalyst Screening

Ethylene epoxidation is industrially and commercially one of the most important selective oxidations. Silver catalysts have been state-of-the-art for decades, their efficiency steadily improving with empirical discoveries of dopants and co-catalysts. Herein, we perform a computational screening of the metals in the periodic table, identify prospective superior catalysts and experimentally demonstrate that Ag/CuPb, Ag/CuCd and Ag/CuTl outperform the pure-Ag catalysts, while they still confer an easily scalable synthesis protocol. Furthermore, we show that to harness the potential of computationally-led discovery of catalysts fully, it is essential to include the relevant in situ conditions e.g., surface oxidation, parasitic side reactions and ethylene epoxide decomposition, as neglecting such effects leads to erroneous predictions. We combine ab initio calculations, scaling relations, and rigorous reactor microkinetic modelling, which goes beyond conventional simplified steady-state or rate-determining modelling on immutable catalyst surfaces. The modelling insights have enabled us to both synthesise novel catalysts and theoretically understand experimental findings, thus, bridging the gap between first-principles simulations and industrial applications. We show that the computational catalyst design can be easily extended to include larger reaction networks and other effects, such as surface oxidations. The feasibility was confirmed by experimental agreement

Heterogeneously catalyzed lignin depolymerization

Biomass offers a unique resource for the sustainable production of bio-derived chemical and fuels as drop-in replacements for the current fossil fuel products. Lignin represents a major component of lignocellulosic biomass, but is particularly recalcitrant for valorization by existing chemical technologies due to its complex cross-linking polymeric network. Here, we highlight a range of catalytic approaches to lignin depolymerisation for the production of aromatic bio-oil and monomeric oxygenates

The persistence of cognitive biases in financial decisions across economic groups

Data availability: All data will be posted open access via https://psyarxiv.com/mrxy6/ and in interactive form via https://public.tableau.com/app/profile/kai.ruggeri. We will post these only once an accepted version of all analyses is possible to avoid confusion based on version control.While economic inequality continues to rise within countries, efforts to address it have been largely ineffective, particularly those involving behavioral approaches. It is often implied but not tested that choice patterns among low-income individuals may be a factor impeding behavioral interventions aimed at improving upward economic mobility. To test this, we assessed rates of ten cognitive biases across nearly 5000 participants from 27 countries. Our analyses were primarily focused on 1458 individuals that were either low-income adults or individuals who grew up in disadvantaged households but had above-average financial well-being as adults, known as positive deviants. Using discrete and complex models, we find evidence of no differences within or between groups or countries. We therefore conclude that choices impeded by cognitive biases alone cannot explain why some individuals do not experience upward economic mobility. Policies must combine both behavioral and structural interventions to improve financial well-being across populations.This research was supported in part by the National Science Foundation (#2218595) and by Undergraduate Global Engagement at Columbia University. Additional support was provided to individual researchers from the Columbia University Office of the Provost, Masaryk University Centre for International Cooperation, and the Benjamin A. Gilman International Fund from the United States Department of State. This research was funded in part, by the UKRI [MR/N013468/1]

The psychology and policy of overcoming economic inequality

Data and materials’ availability: All data are publicly available for the survey data used (https://osf.io/njd62/) and from the UN Gender Inequality Index (https://hdr.undp.org/data-center/documentation-and-downloads). Financial transaction data were provided through an agreement with Columbia Business School.Recent arguments claim that behavioral science has focused – to its detriment – on the individual over the system when construing behavioral interventions. In this commentary, we argue that tackling economic inequality using both framings in tandem is invaluable. By studying individuals who have overcome inequality, “positive deviants,” and the system limitations they navigate, we offer potentially greater policy solutions.This research was supported in part by the National Science Foundation (no. 2218595) and by Undergraduate Global Engagement at Columbia University. Additional support was provided to individual researchers from the Columbia University Office of the Provost, Masaryk University Centre for International Cooperation, and the Benjamin A. Gilman International Fund from the United States Department of State

Underappreciated and Complex Role of Nitrous Acid in Aromatic Nitration under Mild Environmental Conditions: The Case of Activated Methoxyphenols

Many ambiguities surround the possible mechanisms of colored and toxic nitrophenols formation in natural systems. Nitration of a biologically and environmentally relevant aromatic compound, guaiacol (2-methoxyphenol), under mild aqueous-phase conditions (ambient temperatures, pH 4.5) was investigated by a temperature-dependent experimental modeling coupled to extensive ab initio calculations to obtain the activation energies of the modeled reaction pathways. The importance of dark nonradical reactions is emphasized, involving nitrous (HNO2) and peroxynitrous (HOONO) acids. Oxidation by HOONO is shown to proceed via a nonradical pathway, possibly involving the nitronium ion (NO2+) formation. Using quantum chemical calculations at the MP2/6-31++g(d,p) level, NO2 is shown capable of abstracting a hydrogen atom from the phenolic group on the aromatic ring. In a protic solvent, the corresponding aryl radical can combine with HNO2 to yield OH and, after a subsequent oxidation step, nitrated aromatic products. The demonstrated chemistry is especially important for understanding the aging of nighttime atmospheric deliquesced aerosol. The relevance should be further investigated in the atmospheric gaseous phase. The results of this study have direct implications for accurate modeling of the burden of toxic nitroaromatic pollutants, and the formation of atmospheric brown carbon and its associated influence on Earth\u27s albedo and climate forcing

Hydrogenation and hydrodeoxygenation of aromatic lignin monomers over Cu/C, Ni/C, Pd/C, Pt/C, Rh/C and Ru/C catalysts: Mechanisms, reaction micro-kinetic modelling and quantitative structure-activity relationships

In this integrated in silico and experimental study, the activity, selectivity and mechanisms of commercially-available noble and transition metal heterogeneous catalysts, on neutral (carbon) support were investigated for hydrodeoxygenation (HDO) of eugenol. The latter was selected as a model compound of lignin building blocks. An influence of the process operating conditions (temperature, pressure and initial solid loading) on the reaction pathway and product distribution was studied as well. The previously-proposed reaction network for phenols HDO over Ru/C was found valid also for other platinum-group- (Pd, Pt and Rh) and non-noble (Cu or Ni) metallic clusters supported on C. Ru/C system exhibited the best HDO turnover performance, followed by the Rh/C, which especially demonstrated an excellent hydrogenation activity. Pt and Pd showed low deoxygenation and moderate hydrogenation activity. Kinetic parameters for all reactions on the surface were determined for all tested metals with a micro-kinetic model, by regression analysis on the foundation of 5760 experimentally-determined concentration values. Computation took into account resistances caused by transport phenomena, adsorption/desorption kinetics, and especially surface and bulk reaction kinetics. Ratio between adsorption and desorption rate constants for dissolved saturated, aromatic and hydrogen species were predicted, indicating a notable coverage effect on the catalyst reactivity. The saturation of functionalised benzene ring was approximately 3-, 11-, 32-, 10-, and 6-times faster than the C–O hydrogenolysis over ruthenium, platinum, palladium, rhodium and nickel, respectively. Methoxy group removal is easier from aromatics, compared to aliphatic species and also compared to the hydroxyl group removal. The heteroatom bond breaking for 2-methoxy-4-propylcyclohexanol proceed mostly via catechol-type diol formation, and subsequently, de-hydroxylation, particularly observable on Pt

Mechanism, ab initio calculations and microkinetics of straight-chain alcohol, ether, ester, aldehyde and carboxylic acid hydrodeoxygenation over Ni-Mo catalyst

Hydrotreatment of bio-based model compounds was investigated in a three-phase slurry reactor over pre-sulphided NiMo/γ-Al2O3 bifunctional catalyst. Experimental results were supported by comprehensive in silico studies. Mathematical microkinetic model was developed for mass transfer phenomena, adsorption, desorption and surface kinetics description, while quantum chemical calculations were performed for the proposed reaction mechanism validation. Every moiety followed the same chemical reduction sequence as its predecessor down the oxidation ladder, except of aldehyde. Experiments using hexanal as a model compound resulted in its extraordinary high concentrations in liquid phase and on the catalyst surface, which led to mutual aldol condensation. However, this reaction was not observed when aldehyde was formed as an intermediate from hexanoic acid or methyl hexanoate, due to its low concentration and high hydrogen availability which promoted further hydrogenation into hexanol. C12/C6 (aldol condensation/hydrogenation) product ratio increased with higher temperature, reflecting higher activation energy (EA) for hexanal condensation compared to negligible hydrogenation energy barrier, confirmed by density functional theory (DFT) calculations. Primary alcohols are more resistant to HDO compared to secondary counterpart (studied in previous work) over NiMo/γ-Al2O3, specifically; the activation energy of 1-hexanol deoxygenation to olefin was 43% higher compared to secondary hexanols according to microkinetic model, and 45% higher according to quantum mechanics calculations. Primary alcohols are also extensively dehydrated into ethers, which was never the case for secondary alcohols at tested reaction conditions, while aldehydes are much easier to hydrogenate than ketones, which cannot undergo C–C coupling reactions

Multiscale modelling from quantum level to reactor scale: An example of ethylene epoxidation on silver catalysts

Ethylene epoxidation is one of the most important selective chemical oxidations in industry. For a controlled transformation of ethylene (ethene) into epoxide, silver is the only commercially suitable catalyst. Although it is usually doped, even with pristine silver activity, selectivity, and stability vary strongly with facets. In this work, we use this reaction on Ag(111) and Ag(100) as a classical formation model to demonstrate the capabilities of physical multiscale modelling, to show why Ag(100) nanocubes offer superior catalysis, and to optimise reactivity. First, we describe the elementary reactions on pristine surfaces with the quantum chemistry calculations, using density functional theory (DFT). The free energies of all intermediates, kinetic rates from the transition state theory and adsorption/desorption equilibria are calculated from first principles. These results are applied to kinetic Monte Carlo (kMC) simulations, where the spatio-temporal evolution of the system on a meso-scale can be followed. The differences in activity, concentration, selectivity, and apparent activation energy are observed, investigated, and analysed. Lastly, mean-field concepts – micro-kinetics and computational fluid dynamics (CFD) – are used to simulate how the synthesis proceeds in a reactor. Mechanism, catalytic coverage and the effects of pressure, temperature, and particle composition, size and shape on the performance are evaluated. We show that multiscale modelling is a powerful instrumental approach for real unit engineering, while the level of detail required is dictated by the purpose of a representation and available resources