Reaction Pathways Research Articles

Evolution mechanism of organic macromolecular structure during lignite pyrolysis

Understanding the mechanisms governing coal pyrolysis reactions, particularly in relation to the coal macromolecular structure, is crucial for improving energy efficiency and facilitating the transition of coal into a clean energy source. This study employs cutting-edge techniques, such as High-Resolution Transmission Electron Microscopy (HRTEM) and Thermogravimetric Analysis coupled with Fourier Transform Infrared Spectroscopy and Mass Spectrometry (TG–FTIR–MS), to analyze lignite and its residual solid samples subjected to pyrolysis across a range of temperatures from 300 °C to 1100 °C. The variational characteristics of the macromolecular structure during coal pyrolysis are examined. Utilizing molecular dynamics simulations, we analyze the evolution mechanism of the macromolecular carbon structure of organic matter during the coal pyrolysis process. The results show that the pyrolysis can be divided into three distinct phases: activation (30–300 °C), pyrolysis (300–650 °C), and condensation (650–1200 °C). During these phases, the coal structure undergoes complex transformations, including folding, twisting, shedding of small molecular side chains, and breaking of macromolecular side chains, ultimately leading to the directional arrangement of structural fragments. The structural units initially undergo decomposition, followed by growth and alignment in a certain direction. The spatial distribution of aromatic structural units evolves from local ordering to complete disordering, culminating in larger-scale, three-dimensional ordering. The order of bond breaking within the macromolecular structure of lignite pyrolysis is: oxygen-containing functional groups (such as C–O and COOH) > aliphatic structure (N–C and C–C) > aromatic structure (CC). By uncovering the reaction intermediates and pathways involved in lignite pyrolysis, this research provides a comprehensive quantitative description of the coal pyrolysis process. These insights offer invaluable theoretical support for the industrial-scale pyrolysis of coal, paving the way for more efficient and sustainable utilization of this crucial energy resource.

Numerical Investigation of Hydrogen Role on Detonation of CH4/H2/air Mixtures

ABSTRACT Steady one-dimensional Zeldovich-von Neumann-Dӧring (ZND) calculation and thermo-chemical analysis are performed to investigate the hydrogen role on ZND detonation of CH4/H2/air mixtures. Different hydrogen blend ratios (i.e. Hbr) ranging from 0% to 100% are selected in this paper. The results show that hydrogen blend ratio has a significant impact on the ZND detonation reaction pathway of stoichiometric CH4-air mixtures. When Hbr ≤ 20%, CH4 is converted to CO2 by route 1: CH4 => CH3 => C2H6 => … => CO2 and route 2: CH4 => CH3 => CH3O => CH2O => HCO => CO => CO2. When Hbr ≥ 50%, CH3 in route 2 is directly converted to CH2O through R97 (CH3 + O <=> CH2O + H). This causes different ZND detonation structures. The induction length decreases with hydrogen addition. This is because R0 (H + O2 <=> O + OH) governs the heat release during the induction stage, enhancing the energy absorption in induction stage and the molecular thermal decomposition after leading shock wave. Finally, the effect of hydrogen blend ratio on the detonation cell size is explored, and a prediction model of detonation cell size incorporated with detonation stability parameter and induction length is developed for CH4/H2/air mixtures.

Liquid Metal Alloys Enable Efficient Formate Electrosynthesis

AbstractLiquid metals are an interesting class of materials with the unique combination of metallic nature and liquid fluidity, and have recently been explored in many emerging fields. Their potential applications in catalysis, unfortunately, remain largely untapped. Herein, Ga‐mediated liquid metal alloying as an effective strategy is demonstrated to prepare functional alloys for catalysis. The alloying is carried out by dissolving indium or tin pellets in liquid gallium at room temperature or assisted by gentle heating, giving rise to binary Ga1−xInx and Ga1−xSnx liquid metal alloys with tunable chemical compositions. When further subjected to ultrasonication in water, they are ruptured into nanosized particles with liquid metal cores and thin surface oxide shells. Electrochemical measurements reveal that the liquid metal alloying significantly promotes electrocatalytic CO2 reduction to formate. Taking Ga0.75In0.25 as an example, its formate Faradaic efficiency is enhanced by 10%–20% compared to those of Ga and In, and its formate partial current density is 4–6 times larger than those of Ga and In. This enhancement is rationalized via computational simulations showing that the surrounding of In active sites with Ga atoms deactivates the undesirable reaction pathways to CO or H2, and facilitates selective formate electrosynthesis.

Engineering Reaction Pathway to Harmonize the Competition between NRR and HER for Efficient Photocatalytic Ammonia Synthesis

Engineering Reaction Pathway to Harmonize the Competition between NRR and HER for Efficient Photocatalytic Ammonia Synthesis

Investigations of Combustion Characteristics of N-Dodecane/Air Mixtures at High Temperatures Through Laminar Burning Velocity Measurements

ABSTRACT In this work, combustion characteristics of premixed n-dodecane/air mixtures are investigated at elevated mixture temperatures through laminar burning velocity measurements at atmospheric pressure and elevated temperatures using an externally heated diverging channel method. The experiments were conducted up to high-temperature conditions of 610 K at varying equivalence ratios (ϕ = 0.7–1.3) to mimic the conditions of practical application devices. With an increase in the mixture temperature, the laminar burning velocity increases because of the rise in reactant enthalpy. The peak laminar burning velocity is observed at ϕ = 1.1 for all the mixture temperatures, except at 600 K, where the maximum laminar burning velocity is observed for stoichiometric conditions. The minimum temperature exponent exists for a slightly rich mixture condition (ϕ = 1.1). Out of all mechanisms, the laminar burning velocity predictions using the Lawrence Livermore National Laboratory model are consistent with the present data at all mixture temperatures. Normalized sensitivity analysis is analyzed using the Lawrence Livermore National Laboratory mechanism to understand the key reactions affecting the laminar burning velocity of the n-dodecane/air mixture. The chain branching reaction R16: H + O2 <=> O + OH has a major influence on the enhancement of the laminar burning velocity. Reaction pathway analysis is carried out at stoichiometric conditions for mixture temperatures of 400 K and 600 K, where it is observed that the elemental flux of the reaction, converting CO to CO2, gets reduced by 42.91% at the high-temperature condition.

Numerical investigation of the hydrogen-enriched ammonia-diesel RCCI combustion engine

Incorporating hydrogen into the fuel blend of ammonia/diesel in reactivity controlled compression combustion (RCCI) engines, while maintaining high indicated mean effective pressure (IMEP) and combustion efficiency (CE), presents a promising approach for mitigating nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), unburnt ammonia emissions and nitrous oxide (N2O) greenhouse gas (GHG)-a pressing challenge in the field. By supplementing ammonia/diesel combustion with hydrogen, potential issues related to incomplete combustion can be mitigated, along with a reduction in intake valve close temperature (TIVC). This study aims to assess the impact of hydrogen enrichment on combustion characteristics in RCCI engines utilizing ammonia and diesel as fuels, employing the kinetic mechanism of combustion reactions within Converge software. The effect of TIVC on key engine parameters, including in-cylinder pressure, heat release rate (HRR), CE, IMEP, and exhaust emissions, are analyzed by considering chemical reaction pathways. The findings reveal that introducing hydrogen into the ammonia /diesel RCCI combustion blend, leads to significant enhancements in CE and IMEP while simultaneously lowering emissions of CO, HC, unburnt ammonia, and N2O greenhouse gas (GHG). Specifically, when utilizing 80 % ammonia energy fraction (AEF) without hydrogen, minimum TIVC of 440 K is necessary to prevent incomplete combustion, increasing NOx emissions by approximately 20 g/kWh. However, by addition of 20 % hydrogen energy fraction (HEF) into the fuel mixture, the TIVC requirement drops to 380 K, thereby reducing NOx emissions to around 13 g/kWh, while maintaining consistent level of N2O GHG (2.7 g/kWh).

Hierarchical Modeling of the Local Reaction Environment in Electrocatalysis.

ConspectusElectrocatalytic reactions, such as oxygen reduction/evolution reactions and CO2 reduction reaction that are pivotal for the energy transition, are multistep processes that occur in a nanoscale electric double layer (EDL) at a solid-liquid interface. Conventional analyses based on the Sabatier principle, using binding energies or effective electronic structure properties such as the d-band center as descriptors, are able to grasp overall trends in catalytic activity in specific groups of catalysts. However, thermodynamic approaches often fail to account for electrolyte effects that arise in the EDL, including pH, cation, and anion effects. These effects exert strong impacts on electrocatalytic reactions. There is growing consensus that the local reaction environment (LRE) prevailing in the EDL is the key to deciphering these complex and hitherto perplexing electrolyte effects. Increasing attention is thus paid to designing electrolyte properties, positioning the LRE at center stage. To this end, unraveling the LRE is becoming essential for designing electrocatalysts with specifically tailored properties, which could enable much needed breakthroughs in electrochemical energy science.Theory and modeling are getting more and more important and powerful in addressing this multifaceted problem that involves physical phenomena at different scales and interacting in a multidimensional parametric space. Theoretical models developed for this purpose should treat intrinsic multistep kinetics of electrocatalytic reactions, EDL effects from subnm scale to the scale of 10 nm, and mass transport phenomena bridging scales from <0.1 to 100 μm. Given the diverse physical phenomena and scales involved, it is evident that the challenge at hand surpasses the capabilities of any single theoretical or computational approach.In this Account, we present a hierarchical theoretical framework to address the above challenge. It seamlessly integrates several modules: (i) microkinetic modeling that accounts for various reaction pathways; (ii) an LRE model that describes the interfacial region extending from the nanometric EDL continuously to the solution bulk; (iii) first-principles calculations that provide parameters, e.g., adsorption energies, activation barriers and EDL parameters. The microkinetic model considers all elementary steps without designating an a priori rate-determining step. The kinetics of these elementary steps are expressed in terms of local concentrations, potential and electric field that are codetermined by EDL charging and mass transport in the LRE model. Vital insights on electrode kinetic phenomena, i.e., potential-dependent Tafel slopes, cation effects, and pH effects, obtained from this hierarchical framework are then reviewed. Finally, an outlook on further improvement of the model framework is presented, in view of recent developments in first-principles based simulation of electrocatalysis, observations of dynamic reconstruction of catalysts, and machine-learning assisted computational simulations.

Feasibility of producing 225Ac via thermal neutron irradiation of 226Ra: A systematic theoretical study

With a suitable half-life and abundant radiolabeling strategy, 225Ac has become one of the most promising radionuclides in the area of targeted alpha therapy. However, limited radionuclide supply is threatening the development of 225Ac related endoradiotherapy dramatically. As the parent nuclide of 225Ac, 229Th can be produced via 226Ra(3n, 2β)229Th reaction in a nuclear reactor. However, related practice has not been conducted in large scale, since the nuclear reaction pathway for producing 229Th is complicated. In this work, the feasibility of producing 225Ac/229Th in a reactor was confirmed by systematic theoretical calculations, and a procedure that combines irradiation with separation process was proposed. The results show that 176 MBq of 229Th can be produced by irradiating 1.0 g of 226Ra with a neutron flux density of 1 × 1015 n cm−2 s−1 for 90 days. This will generate 150 MBq of 225Ac monthly from a radionuclide generator, which is sufficient for the single treatment cycle of 200 patients each year considering the radioactivity loss in radiochemical separation, transfer and radiolabeling process. In addition, this irradiation process will also produce 37.8 GBq 227Ac for the preparation of 227Ac-227Th-223Ra generator. In general, the production of 225Ac by neutron irradiation of 226Ra in reactor is practicable and holds potential to alleviate the shortage of current supply of 225Ac.

Experimental and kinetic study on the solar-driven iron-based chemical looping dry reforming of methane

The chemical looping dry reforming of methane (CL-DRM) represents a promising pathway for large-scale engineering applications of thermochemical decarbonization techniques. To elucidate the intricate reaction mechanism of CL-DRM, a comprehensive kinetic model encompassing both gas-phase reactions and ferrite surface reactions is developed in this study. This model can serve as a numerical foundation for tracing the reaction progression of comparable iron-based oxygen carriers, allowing visualization of all reaction pathways and further determination of optimal reaction conditions. Besides, foam-structured materials employing NiO-doped CoFe2O4 as oxygen carriers were prepared to conduct application experiments for the CL-DRM on a self-designed solar thermochemical platform. The experimental outcomes, obtained under temperature conditions guided by numerical predictions, validate the promising feasibility of employing Ni-doped ferrite in the CL-DRM reaction system. At a reaction temperature of only 1150 K, remarkable peaks in H2 yield of 23.5 mLmin−1g−1, CO yield of 11.6 mLmin−1g−1, and CH4 conversion around 90% are attained, with a net solar-to-fuel conversion efficiency of 1.93%. A comparative analysis conducted with the conventional two-step thermochemical cycle under the same experimental setup underscores the notable advantages of CL-DRM in terms of syngas production capacity and conversion efficiency. Consequently, CL-DRM can be regarded as a pivotal transition towards the realization of a fully carbon-free thermochemical technology.

Cratoxylum formosum ssp. pruniflorum induces gastric cancer cell apoptosis and pyroptosis through the elevation of ROS and cell cycle arrest.

Cratoxylum formosum ssp. pruniflorum (CF), a traditional medicinal plant in Southern China, is widely recognized as a popular medicinal and tea plant traditionally utilized by diverse linguistic groups in the region for the treatment of gastrointestinal ailments. The objective of this study was to explore the active components and mechanisms of CF against gastric cancer (GC). The chemical ingredients of CF were obtained by using UPLC-MS/MS-based metabolomics. MGC-803 and HGC-27 cells were employed to investigate the direct anti-GC effect. The potential targets and signaling pathway of CF were identified through network pharmacology and proteomics, followed by subsequent experimental validation. Through UPLC-MS/MS metabolomics analysis, a total of 197 chemical ingredients were identified in CF leaves. Network pharmacology and proteomics techniques revealed 25 potential targets for GC, with a protein-protein interaction (PPI) network highlighting 12 cores targets, including CTNNB1, CDK2, et al. Furthermore, seven key CF ingredients - vismione B, feruloylcholine, α-amyrin, vanillic acid, galangin, cinnamic acid, and caffeic acid - were found to mediate anti-GC effects through pathways such as reactive oxygen species (ROS) and cell cycle signaling pathway. In vitro experiments demonstrated that CF significantly inhibited the proliferation and migration of GC cells, increased intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and lactate dehydrogenase (LDH) levels, arrested the cell cycle at the S-phase, induced apoptosis and pyroptosis, and upregulated expression of apoptosis proteins (Bax, Bax/Bcl-2, cleaved-Caspase-3/Caspase-3), and pyroptosis proteins (GSDMD-N/GSDMD and GSDME-N/GSDME), while downregulating expression of cell cycle proteins (CDK2 and cyclin A1) as well as necroptosis proteins (RIP1 and MLKL). Collectively, these findings reveal CF's therapeutic potential against GC by the augmentation of ROS production, cell cycle arrest, promotion of apoptosis, and pyroptosis, offering valuable evidence for the development and utilization of CF in clinical settings.

Batch and Continuous-Flow Electrochemical Geminal Difluorination of Indeno[1,2-c]furans.

An electrochemical gem-difluorination of indeno[1,2-c]furans using commercially available and easy-to-use triethylamine trihydrofluoride as both the electrolyte and fluorinating agent was developed. Remarkably, different reaction pathways of indeno[1,2-c]furans, i.e., paired electrolysis and net oxidation, are operative in a batch reactor and a continuous-flow microreactor to afford the corresponding gem-difluorinated indanones and indenones, respectively.

Collisional alignment and molecular rotation control the chemi-ionization of individual conformers of hydroquinone with metastable neon.

The relationship between the shape of a molecule and its chemical reactivity is a central tenet in chemistry. However, the influence of the molecular geometry on reactivity can be subtle and result from several opposing effects. Here, using a crossed-molecular-beam experiment in which individual rotational quantum states of specific conformers of a molecule are separated, we study the chemi-ionization reaction of hydroquinone with metastable neon atoms. We show that collision-induced alignment of the reaction partners caused by geometry-dependent long-range forces influences reaction pathways, which is, however, countered by molecular rotation. The present work provides insights into the conformation-specific stereodynamics of complex polyatomic systems and illustrates the capability of advanced molecule-control techniques to unravel these effects.

Cooperation of Strong Electric Field and H2O Dissociation on Co3O4-Decorated SiC Rods for Photodriven CO2 Methanation with 100% Selectivity.

Solar-driven methanation of carbon dioxide (CO2) with water (H2O) has emerged as an important strategy for achieving both carbon neutrality and fuel production. The selective methanation of CO2 was often hindered by the sluggish kinetics and the multiple competition of other C1 byproducts. To overcome this bottleneck, we utilized a biomass synthesis method to synthesize SiC rods and then constructed a direct Z-scheme heterojunction Co3O4/SiC catalyst. The substantial difference in work functions between SiC and Co3O4 served as a significant source of the charge driving force, facilitating the conversion of CO2 to CH4. The high-valent cobalt Co(IV) in Co3O4 acts as an active species to promote efficient dissociation of water. This favorable condition greatly enhanced the likelihood of a high concentration of electrons and protons around a single site on the catalyst surface for CO2 methanation. DFT calculation showed that the energy barrier of CO2 hydrogenation was significantly reduced at the Co3O4/SiC heterojunction interface, which changed the reaction pathway and completely converted the product from CO to CH4. The optimum CH4 evolution rate of Co3O4/SiC samples was 21.3 μmol g-1 h-1 with 100% selectivity. This study has an important guiding significance for the selective regulation of CO2 to CH4 products in photocatalysis applications.

Unveiling the oxygen addition kinetics of 1-Hydroxy-2-Hexyl and 2-Hydroxy-1-Hexyl at low temperature

Hydroxyalkyl radicals formed from addition of OH to alkenes play a crucial role in the oxidation of alkenes. The oxygen addition kinetics of 1‑hydroxy-2-hexyl and 2‑hydroxy-1-hexyl at low temperature has been investigated by using quantum chemical calculations coupled with the RRKM/master equation simulations. The main reaction pathways that occur on the potential energy surfaces of HOC6H12 + O2 were studied at the CCSD(T)/CBS(cc-pV[T,Q]Z)//M06–2X/jun-cc-pVTZ level. Rate coefficients of key reactions have been determined at the high-pressure limit and the falloff region. The isomerizations of hydroxyhexylperoxy to hydroperoxy-hydroxyalkyl are found to be of great importance. The formed hydroperoxy-hydroxyalkyl radicals can either dissociate rapidly into aldehydes and ketones, or be accumulated to participate in the second oxygen addition. The formation of formaldehyde, n-pentanal and OH via the Waddington mechanism is among the most important product channels. H2O elimination pathways are identified for the most stable HOQOOH intermediates, with the radical site at α-carbon to the hydroxy group. The present study recognizes those hydroperoxy-hydroxyalkyl radicals that are able to undergo the second oxygen addition. Kinetic analysis reveals that the facile formation via 1,5 or 1,6 H-transfer and lack of fast decomposition pathways combine to enable the accumulation of particular hydroperoxy-hydroxyalkyl radicals, facilitating their involvement in subsequent chain-branching chemistry. This study further illuminates the intricate understanding of the low temperature chemistry of larger alkenes.

Low Temperature NO and CO Conversion with a Mechanistic Approach on Ru-Composed Cerium Oxide.

Catalytic reduction of NO with CO at a lower temperature is an extremely challenging task, thus requiring conceivable surfaces to overcome such issues. Ru-substituted CeO2 catalysts prepared via the solution combustion method were employed in CO oxidation and NO-CO conversion studies. The characterization for material formation and surface structure was carried out through XRD, SEM, TEM, and BET surface area. The catalytic study revealed the promising behavior of 5% Ru in CeO2 for the 100% conversion of NO-CO at 150 °C, proving it to be an excellent exhaust material. These observed results are also supported by temperature-programmed studies, i.e. TPD of NO and CO in addition to NH3-TPD and H2-TPR for their convincible surface interaction that is inclined toward a significant change in the conversion path. Additionally, the proposed mechanism, based on the experimental evidence, sheds light on the NO-CO redox reaction, directing the reaction pathway toward the Langmuir-Hinshelwood and Mars-Van Krevelen-type route. Moreover, the exceptional performance can be attributed to the strategic incorporation of Ru in CeO2, where the strong interaction of Ru-Ce is able to gain a high synergy for NO and CO conversion.

Polymer and micellar catalysis in d-fructose oxidation by imidazolium fluorochromate: A kinetic and mechanistic study

This work investigated the oxidation of d-fructose using imidazolium fluorochromate (IFC) as an oxidant and analyzed how sodium dodecyl sulfate (SDS) and polyethylene glycol (PEG-400) affected the reaction kinetics. The process exhibited a unit-order dependence on IFC, d-fructose, and perchloric acid concentration. Perchloric acid was the primary source of hydrogen ions in the reaction mixture. The stoichiometry of the reaction indicated that 3 mol of d-fructose requires 4 mol of IFC. Acrylonitrile, a radical-generating species, did not impact the reaction rate, indicating the absence of a free radical intermediate. The reaction rate decreases as the Mn (II) ions concentration increases, suggesting the involvement of Cr (IV) species in the reaction. The dielectric value of the reaction medium (D) had an inverse effect on the rate, and the outcomes were consistent with the Amis (log k1 and 1/D) and Kirkwood plots (log k1 and (D-1/2D+1)), indicating the presence of dipole-dipole interactions in the process. SDS and PEG-400 catalyzed the reaction. The reaction showed significant catalysis before reaching the critical micelle concentration (CMC). However, the observed rate constants stabilized at higher SDS concentrations exceeding the CMC. Piszkiewicz's cooperativity model was employed to describe the surfactant catalysis, while the Benesi-Hildebrand equation was utilized to explain polymer catalysis. The activation parameters are ΔH† = 44.3 ± 1.3 kJ mol−1, and ΔS† = −133.4 ± 4.3 J K−1 mol−1. The products of the reaction have been identified by spectral analysis as d-arabinoniclactone and formic acid. The formation of an ester complex followed by its decomposition was proposed as the rate-limiting step in the proposed mechanistic reaction pathway.

Chemical and engineering bases for green H2O2 production and related oxidation and ammoximation of olefins and analogues

Abstract Plastics, fibers, and rubber are three mainstream synthetic materials that are essential to our daily life and contribute significantly to the quality of our life. The production of the monomers of these synthetic polymers usually involves oxidation or ammoximation reactions of olefins and analogues. However, the utilization of the C, O, and N atoms in current industrial processes is less than 80%, which represents the most environmentally polluting processes for the production of basic chemicals. Through innovation and integration of catalytic materials, new reaction pathways, and reaction engineering, Research Institute of Petroleum Processing, Sinopec Co., Ltd. (RIPP) and its collaborators have developed unique H2O2-centered oxidation/ammoximation technologies of olefins and analogues, which has formed a ¥500 billion emerging industry and driven trillions of downstream industries. The chemical and engineering bases of the production technologies mainly involve the integration of slurry-bed reactors and microsphere catalysts to enhance H2O2 production, H2O2 propylene/chloropropylene epoxidation for the production of propylene oxide (PO)/epichlorohydrin (ECH), and integration of H2O2 cyclohexanone ammoximation and membrane separation to innovate the caprolactam production process. This review briefly summarizes the whole process from the acquisition of scientific knowledge to the formation of an industrial production technology by RIPP. Moreover, the scientific frontiers of H2O2 production and related oxidation/ammoximation processes of olefins and analogues are reviewed, and new technological growth points are envisaged, aiming at keeping China as one of the leaders in the development of the science and technologies in H2O2 production and utilization.

Aluminium in der Chemie der Frustrierten Lewis‐Paare

AbstractDieser Übersichtsartikel beschreibt die Entwicklung der Verwendung von Aluminiumverbindungen in der Chemie der frustrierten Lewis‐Paare (FLPs) in den letzten 14 Jahren. Es werden die Synthese, die Reaktivität und die katalytischen Anwendungen von intermolekularen, intramolekularen und sogenannten versteckten FLPs mit Phosphor‐, Stickstoff‐ und Kohlenstoff‐Lewis‐Basen erörtert. Die intrinsisch höhere Acidität von Aluminiumverbindungen im Vergleich zu ihren Bor‐Analoga eröffnet unterschiedliche Reaktionswege. Die Ergebnisse werden in einer mehr oder weniger chronologischen Reihenfolge präsentiert. Es wird gezeigt, dass Al‐FLPs mit einer Vielzahl von polaren und unpolaren Substraten reagieren und sowohl stabile Addukte bilden als auch reversibel Bindungen aktivieren. Folglich werden einige katalytische Anwendungen der Titelverbindungen vorgestellt, wie z. B. die Dimerisierung von Alkinen, die Hydrierung von tert‐butylethylen und Iminen, die Aktivierung von C−F‐Bindungen, die Reduktion von CO2, die Dehydrierung von Aminboran und der Transfer von Ammoniak. Darüber hinaus wurden verschiedene Al‐FLPs als Initiatoren in Polymerisationsreaktionen eingesetzt.

Aluminum in Frustrated Lewis Pair Chemistry.

This review article describes the development of the use of aluminum compounds in the chemistry of frustrated Lewis pairs (FLPs) over the last 14 years. It also discusses the synthesis, reactivity and catalytic applications of intermolecular, intramolecular and so-called hidden FLPs with phosphorus, nitrogen and carbon Lewis bases. The intrinsically higher acidity of aluminum compounds compared to their boron analogs opens up different reaction pathways. The results are presented in a more or less chronological order. It is shown that Al FLPs react with a variety of polar and non-polar substrates and form both stable adducts and reversibly activate bonds. Consequently, some catalytic applications of the title compounds were presented such as dimerization of alkynes, hydrogenation of tert-butyl ethylene and imines, C-F bond activation, reduction of CO2, dehydrogenation of amine borane and transfer of ammonia. In addition, various Al FLPs were used as initiators in polymerization reactions.

Unveiling the Promoting Mechanism of H2 Activation on CuFeOx Catalyst for Low-Temperature CO Oxidation.

The effect of H2 activation on the performance of CuFeOx catalyst for low-temperature CO oxidation was investigated. The characterizations of XRD, XPS, H2-TPR, O2-TPD, and in situ DRIFTS were employed to establish the relationship between physicochemical property and catalytic activity. The results showed that the CuFeOx catalyst activated with H2 at 100 °C displayed higher performance, which achieved 99.6% CO conversion at 175 °C. In addition, the H2 activation promoted the generation of Fe2+ species, and more oxygen vacancy could be formation with higher concentration of Oα species, which improved the migration rate of oxygen species in the reaction process. Furthermore, the reducibility of the catalyst was enhanced significantly, which increased the low-temperature activity. Moreover, the in situ DRIFTS experiments revealed that the reaction pathway of CO oxidation followed MvK mechanism at low temperature (<175 °C), and both MvK and L-H mechanism was involved at high temperature. The Cu+-CO and carbonate species were the main reactive intermediates, and the H2 activation increased the concentration of Cu+ species and accelerated the decomposition carbonate species, thus improving the catalytic performance effectively.