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Offering virtual laboratories to chemical engineering students is likely to extend beyond the COVID-19 era. Thus, there is a need to develop more simulation-based tasks in a wide blend of subjects, spanning thermodynamics, chemical reactions, and unit operations. Molecular and material modeling based on density functional theory (DFT) calculations provides limitless opportunities to train students on how to obtain thermokinetic values that are typically measured experimentally. Through a series of illustrative cases, this contribution provides detailed procedures pertinent to calculating reaction rate constants, standard enthalpies of reactions, redox potentials, equilibrium reaction constants, and surface-assisted mechanisms. We hope that DFT-operated virtual labs will assist students in attaining learning outcomes and promote their self-learning in the above-mentioned subjects. From a broader prospective, the presented case studies are expected to encourage students to appreciate the practical applications of DFT, not only in the academic but also in the industrial domains.

Alumina oxides have been widely utilised as independent catalysts or as support materials for other catalysts. From an environmental perspective, alumina nanoclusters dispersed on surfaces of particulate matter PM12, generated from various combustion processes, play a critical role in the synthesis of environmentally persistent free radicals (EPFRs). Of particular importance are phenoxy-type EPFRs that often act as building blocks for the formation of notorious pollutants. Herein, we present a systematic review of the literature pertinent to structural features of alumina surfaces at the nano-scale and their well-established role in the synthesis of EPFRs. Central to the capacity of alumina surfaces in mediating the formation of EPFRs are their active Lewis acid–base sites. The nature of these sites is very sensitive to hydration scenarios. As evident in electroparamagnetic resonance measurements, more than one category of EPFR forms on alumina surfaces. This generally entails the co-existence of various surface terminations, varying degrees of hydrations, and distinct underlying reaction pathways. The mechanisms for the formation of EPFRs over alumina surfaces involve interactions with terminal OH groups followed by creating genuine chemical bonds with Al3+ sites. Higher concentrations of EPFRs were often detected on alumina surfaces, in reference to other transition metal oxides. We envisage that future studies may focus on the generation of EPFRs from potential precursors other than phenols and catechol, such as brominated species and substituted thiophenols.

During thermal utilization of biomass, a complex array of reactions ensues in the oxidative environment between fragments of the biomass and reactive species. In the low-temperature window, hydroperoxyl (HO 2) radicals assume a central role prior to the establishment of the O/H radical pool. Anisole, cresol, guaiacol and vanillin are often utilized as representative model compounds to comprehend the combustion chemistry of the phenolic entities in biomass and oxygen-containing derived bio-oil. This paper reports thermo-kinetic parameters for the reactions of HO2 radicals with anisole, cresol, guaiacol and vanillin. Computed activation enthalpies entail facile values for H abstraction from the side-chain functional groups in the investigated compounds. H abstraction from the hydroxyl groups incurs lower activation energies in reference to methyl sites in cresol and guaiacol. Hence, H abstraction from the OH sites in these two molecules proceeds at a faster reaction rate constant when compared to abstraction from the methyl site. In the vanillin molecule, abstraction from the aldehydic and hydroxyl sites portrays comparable importance. The effect of scaling vibrational frequencies and the type of applied quantum tunneling on the computed reaction rate constants were thoroughly explored. Analysis of entropies of activation indicates that the transition states exhibit a product-like character. While ignition delay times of fuels often exhibit a profound sensitivity towards initial H abstraction reactions by HO2, we found that ignition delay times of the four title molecules remain almost unchanged when updating literature kinetics models with new reaction rate constants calculated herein. It is anticipated that reported outcomes from this study aid in formulating a better understanding of the complex chemical reactions that dictate oxidative decomposition of oxygenated bio-oil model compounds. The work reports thermo-kinetic parameters for the reactions of HO2 radicals with prominent biomass model compounds. Abstraction from various sites have been explored. The effect of the title reaction in the ignition delay times of these compounds is rather limited. [ABSTRACT FROM AUTHOR]

Catalytic capacity of ceria mainly stems from a facile switch in the Ce oxidation states from +4 to +4 − x. While various experimental and computational studies pinpoint the reduction chemistry of Ce atom through the creation of oxygen vacancies, the analogous process when ceria surface is decorated with cations remains poorly understood. Where such results are available, a synergy between experimental and first principle calculation is scarce. Niobium materials are evolving and their use in catalysis is being widely investigated due to their high surface acidity and thermal and chemical stability. This study aims to report structural and electronic properties of various configurations of mixed Ce–Nb oxides and elaborates on factors that underpin potential catalytic improvements. Evaluations of the samples through X-ray diffraction (XRD), Fourier transform infrared (FTIR), N2-adsorption–desorption, scanning electron microscope (SEM), energy dispersive spectroscope (EDS), and thermogravimetric (TGA) analyses are examined and discussed. First principles density functional theory (DFT) calculations provide structural features of the Ce–Nb solutions at low concentration of Nb via computing atomic charge distribution. Contraction in the lattice parameter after Nb doping was confirmed with both XRD and DFT results. SEM analysis reveals particle growth at the loading of 50 wt%. FTIR results established the Ce–Nb–O bond at 1,100 cm−1 and the TGA analysis confirms the thermal stability of Nb-doped ceria. Tetrahedral O atoms demonstrate an increase in electronegativity and this in turn facilitates catalytic propensity of the material because the O atoms will exhibit higher affinity for adsorbed reactants. Cerium oxide (CeO2) after Nb doping displays a noticeable band gap narrowing, confirming the possible improvement in the catalytic behavior. The 4d states of the Niobium pentoxide (Nb2O5) is found to fill up the 4f states of CeO2 around the Fermi energy level promoting electrons excitation in the CeO2. Reported electronic, structural, and thermal characteristics herein indicate promising catalytic applications of niobium-promoted ceria.