Reaction Mechanism Research Articles

Thermodynamic model of coal direct chemical looping combustion

ABSTRACT Chemical looping combustion (CLC) technology offers cost-effective CO2 emission reduction. Coal direct chemical looping (CDCL) emerges as a promising solid fuel CLC technology owing to its ability to directly utilize coal without prior gasification, enhancing system integration and efficiency. Despite significant progress in CDCL, challenges persist, including carbon deposition and insufficient oxidation and reduction of oxygen carriers (OCs). This study conducted a thermodynamic equilibrium analysis of a CDCL combustion reactor using Cantera 3.0, a chemical calculation module developed at the California Institute of Technology. The analysis explored the impact of different temperatures, OC-to-coal molar ratios (θ), and OCs types on combustion products. By employing the minimum Gibbs function method and analyzing intrinsic reaction mechanisms, the study provides insights for predicting and optimizing system performance. Thermodynamic equilibrium analysis revealed that with CuO as the OC, insufficient OC (θ < 0.6) led to Cu as the reduction product, while sufficient OC (0.6 < θ < 1.3) yielded Cu and CuO, and excess OC (θ > 1.3) resulted in Cu2O. To optimize CO2 capture, a molar ratio of θ of at least 1.4 and a temperature of at least 800°C are recommended. When Fe2O3 served as the OC, insufficient OC (θ < 0.45) produced Fe and FeO, while excess OC generated FeO and Fe3O4. Optimal operational performance and CO2 capture efficiency required an OC-to-coal molar ratio exceeding 1.4 and a temperature higher than 700°C. This study demonstrates that in CDCL combustion systems, selecting appropriate OCs, temperatures, and OC-to-coal molar ratios ensures stable and efficient combustion and CO2 capture. These findings offer crucial guidance for optimizing system operation.

Superhydrophilicity and Electronic Modulation on Self-Supported Lignin-Derived Carbon Coupled with NiO@MoNi4 for Enhancing Urea Electrolysis.

Developing highly efficient biomass-derived carbon-based electrocatalysts remains challenging for urea electrolysis because most of these electrocatalysts show powder morphology, which can lead to Ostwald ripening during the reaction process, and its reaction mechanism should be further verified. Herein, self-supported lignin-derived carbon coupling NiO@MoNi4 heterojunction (NiO@MoNi4/C) possesses superhydrophilic properties and electronic modulation, boosting the performance of urea electrolysis. Electrochemical results show that an indirect oxidation step for urea oxidation reaction (UOR) and Volmer-Heyrovsky mechanism for hydrogen evolution reaction (HER) occurs on the surface of NiO@MoNi4/C. It displays low potentials for UOR (E10/500/1000 = 1.28/1.41/1.47 V) and for HER (E-10/-500/-1000 = -38/-264/-355 mV) in 1.0 MKOH + 0.5M urea electrolyte solution. The good activity is ascribed to the self-supported lignin-derived carbon and heterojunction, which increases the number of active sites, optimizes electronic structure, and improves electron transfer. Benefiting from the self-supported lignin-derived carbon, NiO@MoNi4/C demonstrates corrosion resistance and superhydrophilicity, which avoids Ostwald ripening and accelerates gas-liquid transfer, thus, maintaining for 100 h at ±1000/±1500 mA cm-2 during the UOR and HER test. This work provides a good catalyst for urea electrolysis and presents a promising way for preparing lignin-derived carbon-based catalysts while expanding the application of lignin-based biomass carbon materials.

Metal–Ligand Cooperation in Dihydrogen Activation by a Cationic Metallogermylene: Enhanced Activity from Tungsten to Molybdenum

Dihydrogen activation by metallogermylenes was investigated experimentally and theoretically. A neutral NHC-coordinated chlorometallogermylene was synthesized and converted to a cationic base-free metallogermylene of molybdenum via chloride abstraction. The cationic molybdogermylene showed enhanced reactivity toward H2 compared to the tungsten analog. The reaction mechanism was investigated by theoretical calculations, which revealed a novel route that proceeds via a new type of metal–ligand cooperative activation between the metal and divalent germanium moiety. The activation energy of this route is much lower than that of the alternative route via an “oxidative addition” type of reaction on the single Ge(II) center, which is generally proposed for organotetrylenes. The features of the frontier orbitals and the origin of the metal effect on the H2 activation are also described.

Highly enhanced reactivity of HCl on the Ag/Au(111) alloy surface via rotational quantum state excitation.

Rotational excitations of reactants are often considered to have little impact on chemical reactivity compared to the excitations of vibrational modes and translational motion. Here, we reveal a significant influence of the rotational excitation of HCl on its dissociation on an Ag/Au(111) alloy surface. This finding is based on six-dimensional time-dependent wave packet calculations performed on an accurately fitted machine learning potential energy surface. Rotational energy is found to be 90 times more effective in driving the reaction than an equivalent amount of translational energy. The reactivity of HCl on Ag/Au(111) is diminished due to a charge transfer effect, which induces a strongly non-monotonic dependence of the minimum energy path on molecular orientation, resulting in the HCl molecule deviating from the minimum barrier. We identify and detail two underlying mechanisms by which rotationally excited HCl can overcome the charge transfer effect between Au and Ag atoms, leading to enhanced reactivity and an intriguing rotational-alignment phenomenon. This finding underscores the profound impact that rotational excitations can exert on molecular reactivity, emphasizing a delicate interplay between various forms of molecular energy and their respective contributions to the reaction mechanism.

Hydrolysis of p-Phenylenediamine Antioxidants: The Reaction Mechanism, Prediction Model, and Potential Impact on Aquatic Toxicity.

While p-phenylenediamine antioxidants (PPDs) pose potential risks to aquatic ecosystems, their environmental persistence and transformation remain ambiguous due to the undefined nature of PPD C-N bond hydrolysis. Here, we investigated the hydrolysis patterns of PPDs by analyzing their hydrolysis half-lives, hydrolysis products around neutral pH (pH 6.0-7.7), and the role of atoms within the C-N bonds in PPDs. Hydrolysis preferentially targets the aromatic secondary amine N with the strongest proton affinity and the C atom of C-N with the highest nucleophilic-attack reactivity. The hydrolysis half-life (t1/2) shortens when the maximum proton affinity of N increases. These results are supported by theoretical calculations, demonstrating a hydrolysis reaction propelled by proton transfer from water to N and complemented by aromatic nucleophilic substitution of N in C-N by water hydroxyl. With the experimental results and the atom reactivity-based predictive model, the t1/2 around neutral pH for 60 PPDs (monitored in environment, commercially available, or under investigation) is determined, showing variations ranging from 2.2 h to 47 days. The model prediction of primary C-N hydrolysis is confirmed through typical PPDs. With the elucidated mechanism and developed model, this research provides new insights into PPD hydrolysis, underscoring its significance in delineating environmental impacts.

Adsorption of Vanadium (V) on Amorphous and Modified Silica

In this work, we investigate V(V) sorption on amorphous and modified silica. Silicon dioxide was obtained from the metallurgical slag. The impact of modification on vanadium sorption was studied. The surface was modified with hydrazides (HDs) and dimethylhydrazides (DMHDs) of the tertiary carbonic Versatic acids CH3R1R2CC(O)OH of the C10–19 fractions. The optimal sorption conditions on the unmodified sorbent were pH 4, 1 h, and 40 °C. The sorption capacity of V(V) ions increased with surface modification. For modified sorbents, the range of action shifted to a more acidic area (2.0–3.0), where the HV10O285− polyanion formed a complex with N′,N′-dimethylhydrazide groups. When studying the kinetics of the V(V) sorption process on silica samples, the optimum time of adsorption equilibrium establishment (10 min) and reaction mechanism were determined. The sorption process was significantly accelerated by surface modification. The vanadium sorption process is described by pseudo-second-order kinetics. The study of adsorption isotherms revealed that the vanadium sorption isotherm corresponds to the Langmuir equation. The differences in the extraction of vanadium ions are explained by different sorption mechanisms, which are associated with the variety of vanadium forms in the solution.

Study on the Characteristics of Crystal Formation and Transformation of Alkali-Activated Slag Minerals Induced by Weak Alkali

Strong-alkali activation is a prerequisite needed to ensure the full polymerization activity of alkali slag binder and establish excellent mechanical properties; however, it substantially increases the preparation cost. In this study, the effects of both strong and weak alkaline activators on the activation performance of alkali slag were examined, using a combination of X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy analysis methods. The reaction mechanism was analyzed under different alkaline conditions, and the preparation cost could be significantly reduced without significantly degrading mechanical properties. The results indicate that Ca(OH)2 can stimulate the reactivity of slag, resulting in a 40% decrease in compressive strength (compared to NaOH) but a 25–50% reduction in preparation cost. With increasing Ca(OH)2 dosage, the compressive strength first increases and then decreases. The best excitation effect is achieved at a dosage of 40 g Ca(OH)2 per 450 g GBFS. The formation of aluminosilicate is the main driving force for the observed increase in compressive strength. Excessive dosage of Ca(OH)2 will lead to its deposition in the specimen, thus affecting the development of compressive strength.

Base Promoted Chemoselective Reduction of α‐Keto Amides and α‐Keto Esters with TsNHNH2

AbstractA method for chemoselective reduction of α‐keto amides and α‐keto esters using tosylhydrazine in the presence of NaHCO3 has been developed. A variety of α‐hydroxy amides and α‐hydroxy esters were obtained in good to excellent yields, demonstrating the efficiency of the present protocol. A possible reaction mechanism is proposed based on the deuterium‐labelling experiments.

Platinum Compound on Gold–Magnesia Hybrid Structure: A Theoretical Investigation on Adsorption, Hydrolysis, and Interaction with DNA Purine Bases

Cisplatin-based platinum compounds are important clinical chemotherapeutic agents that participate in most tumor chemotherapy regimens. Through density-functional theory calculations, the formation and stability of the inorganic oxide carrier, the mechanisms of the hydrolysis reaction of the activated platinum compound, and its binding mechanism with DNA bases can be studied. The higher the oxidation state of Pt (II to IV), the more electrons transfer from the magnesia–gold composite material to the platinum compound. After adsorption on the composite carrier, 5d←2p coordination bonds of Pt-N are strengthened. For flat and oblique adsorption modes of cisplatin, there is no significant difference in the density of states of the gold and magnesium oxide film, indicating the maintenance of the heterojunction structural framework. However, there are significant changes in the electronic states of cisplatin itself with different adsorption configurations. In the flat configuration, the band gap width of cisplatin is larger than that of the oblique configuration. The Cl-Pt bond range in the Pt(III) compound shows a clear charge reduction on the magnesia film, indicating the Cl-Pt bond is an active site with the potential for decomposition and hydrolysis. The substitution of chloride ions by water can lead to hydrolysis products, enhancing the polarization of the composite and showing strong charge separation. The hydrolysis of the free platinum compound is endothermic by 0.309 eV, exceeding the small activation energy barrier of 0.399 eV, indicating that hydrolysis of this platinum compound is easily achievable. ADME (absorption, distribution, metabolism, and excretion) prediction parameters indicate that hydrolysis products have good ESOL (Estimated SOLubility) solubility and high gastrointestinal absorption, consistent with Lipinski’s rule. During the coordination reaction process, there are significant changes in the distribution of frontier molecular orbitals, with the HOMO (highest occupied molecular orbital) of the initial state primarily located on the purine base, providing the possibility for electron transfer to the empty orbitals of the platinum compound in the LUMO (lowest unoccupied molecular orbital). The HOMO and HOMO-1 of the transition state and product are mainly distributed on the platinum compound, indicating clear electron transfer and orbital rearrangement. The activation energy barrier for the purine coordination reaction with the hydrolysis products is reduced to 0.61 eV, and the dipole moment gradually decreases to 6.77 Debye during the reaction, indicating a reduction in the system’s charge separation and polarization. This contribution is anticipated to provide a new theoretical clue for developing inorganic oxide carriers of platinum compounds.

Reaction Pathway Regulation for Gaseous and Liquid Products of Electrocatalytic CO2 Reduction under Adsorbate Interactions

AbstractHalide anion adsorption on transition metals can improve the performance of electrochemical CO2 reduction reaction (CO2RR), while the specific reaction mechanisms governing selective CO2RR pathways remain unclear. In this study, we reveal for the first time the distinct pathway switching between gaseous (CO) and liquid products (formate and ethanol) on the well‐defined Ag−Cu nanostructures with controlled chlorination. We show that CO2 conversion to CO on Ag/AgCl can be tuned by adjusting the thickness of AgCl layer, achieving a high selectivity over a broad potential range in a 0.5 M KHCO3 using flow cell. In contrast, the optimized Cl−Ag/Cu system enables the conversion of CO2 into liquid products including formate and ethanol with a total Faradaic efficiency (FE) nearing 100 %, delivering high current densities of 136.3 and 20.8 mA cm−2 at −1.3 V, respectively. In situ infrared experiments and theoretical calculations indicate that the lateral adsorbate of *OCHO intermediate facilitates the thermodynamics of both the CO pathway on Cl−Ag(111) and the formate pathway on Cl−Ag/Cu(111) by reducing Gibbs free energy barriers of each potential‐limit step. This work uncovers the role of chlorination in the tuning of C‐bound or O‐bound intermediates during CO2RR on Ag−Cu catalysts, determining the reaction pathway under lateral adsorbate effects.

1 Using Soil Chemistry through EDXRF to Identify Archaeological Features at the Site of Ulpiana in Kosova

Chemical analysis of archaeological sediments is a research area that has long interested archaeologists but has seen recent developments. It locates concentrations of chemical elements in soils that can be linked to ancient activities responsible for their deposition. The use of X-ray fluorescence spectrometry, a more accessible analytical technique than others, makes it possible to analyze large batches of samples. At Ulpiana, two trenches were studied. In the first area, the presence of a lime pit and a mortar preparation area was identified. The signature of the lime seems to correspond to that produced in a kiln discovered further north. In the second area, a bronze recycling workshop was identified, along with a suspected dye molecule. About the authors Arthur Laenger Arthur Laenger studied history, archaeology, and chemistry at Le Mans University (France) and obtained his PhD in archaeology and the history of the Middle Ages in 2006, under the supervision of A. Durand and A. Martel. His work focuses on the characterization of structures and archaeological sites using an interdisciplinary approach that combines history, archaeology, and chemical soil analysis. Arnaud Martel Arnaud Martel was born in 1974 in Le Mans, France. He undertook studies in chemistry at the Université du Maine, obtaining his PhD in 2001. Subsequently, he conducted postdoctoral research with Prof. G. Guillaumet at ICOA (Orleans, France) and with Prof. H. Ottosson in Uppsala (Sweden). He was appointed assistant professor in 2004 and attained the rank of full professor at the Université du Maine in 2013. His research interests encompass organic chemistry, DFT-assisted elucidation of reaction mechanisms, and analytical chemistry. His research is currently focused on the development of new analytical methodologies applied in a multidisciplinary approach ranging from archaeology to environmental sciences. Aline Durand Aline Durand studied history, latin and anthracology in Paris I Panthéon-Sorbonne University and obtained her PhD under the supervision of R. Fossier and J.-L. Vernet (1991). Assistant professor in Aix-Marseille University (1992-2013), she is full professor of Middle Age history and archaeology at Le Mans University from 2013. She is particularly interested on rural economy of the X th -beginning XIII th centuries in the Mediterranean French area (Languedoc, Provence, Southern French Alps). Her research tries to interweave diverse sources: written documents (diplomatic documentation or agronomic treatises), archaeological data, bioarchaeological and palaeoenvironmental results. She works on agrarian landscapes, vegetal resources management, practices and knowledge on plants. To gain a better understanding of craft production techniques and their environmental impact, she developed an ethnoarchaeological research in Morocco, using archaeological methods observe and record them. Fabien Boucher Fabien Boucher was born in 1978 in Le Mans, France. He first studied chemistry at the University of Maine where he obtained a DUT in Chemistry (the French equivalent of a Bachelor's degree) and continued his studies at the Rennes School of Chemistry (Universityof Rennes). There he obtained an engineering degree in analytical chemistry. After spending more than 10 years in laboratories providing environmental analysis services, he returned to the University of Le Mans as a study engineer. He worked there in particular as a research support in analytical chemistry and participated in the development of new analytical methodologies applied to various fields of chemistry, biology and archaeology.

Pyrolysis kinetics study of nucleic acid detection supplies

AbstractTo investigate the pyrolytic behavior of materials used in nucleic acid detection and unravel their chemical reaction mechanisms at a molecular scale, thermogravimetric experiments were conducted on a range of components: polypropylene (PP) sampling tubes, polyamide/acrylonitrile butadiene styrene (PA/ABS) pharyngeal swab sampling heads, ABS pharyngeal swab rods, and mixtures of pharyngeal swab sampling heads and sampling tubes at heating rates of 10, 20, 30, and 40°C/min employing conversion from 0.1 to 0.9 in 0.1 increments. Employing three model‐free methods—Kissinger–Akahira–Sunose, (KAS) Flynn–Wall–Ozawa, and Friedman—the pyrolysis kinetics of individual components and mixtures were analyzed. The average activation energy were obtained to be 144.0–152.7, 211.4–213.5, 163.3–168.7, and 156.6–167.3 kJ/mol, respectively. Two model‐fitting methods—Coats‐Redfern and Criado—were used to elucidate the chemical reaction mechanisms across various heating rates and conversions. The pre‐exponential factor was calculated. The pyrolytic behavior of pharyngeal swabs was simulated, and the results showed that the most accurate kinetic parameters were obtained by the KAS method.

Fischer-Speier Esterification and Beyond: Recent Mechanicistic Advances

Over the past 130 years, Fischer-Speier esterification has been established as the benchmark method for synthesizing esters from organic acids and alcohols. The reaction’s versatility, arising from the vast combinations of starting materials and the numerous catalytic alternatives to the traditional H2SO4, has maintained its relevance, with a steady flow of publications addressing new developments. This review highlights the most significant contributions to Fischer-Speier esterification over the past five years, with a particular emphasis on mechanistic advancements and innovative catalytic systems. Both homogeneous and heterogeneous catalytic approaches are discussed, including novel catalysts leveraging hydrogen-bonding interactions and systems offering fresh insights into specific reaction mechanisms and atypical methodologies. Some of these catalytic systems, as ionic liquids or sulfonated heterogeneous catalytic precursors, reached excellent yields (&gt;90%), e.g., in the synthesis of fatty acids methyl esters. Also, classic catalysts such as H2SO4 and para-toluen sulfonic acid were optimized for quantitative conversions (e.g., in the esterification of trans-cinnamic acid with methanol). A consistent number of catalysts was studied with model substrates (as benzoic acid in combination with methanol, ethanol, and ethylene glycol), and new activation pathways were presented.

Enhanced Electrochemiluminescence by Knocking Out Gold Active Sites.

Electrochemiluminescence (ECL) of the conventional system of [Ru(bpy)3]2+ luminophore and amine-based coreactants is particularly inefficient on noble metal electrodes. This is due to the formation of a passivating oxide layer on the metal surface inhibiting the electro-oxidation of amines like tri-n-propylamine (TPrA) coreactant, Herein, we demonstrated the enhancement of ECL emission on gold surface by hydroxyl radicals attack that are chemically generated with Cu-Fenton reagent. These radicals selectively deactivate the gold active sites and knockout the metal surface asperities that counterintuitively led to an amplification of the ECL emission. Atomic Force Microscopy shows a massive smoothening of the surface. The electrochemical characterization proves that the involved ECL reaction mechanism switches from direct oxidation to catalytic route, where the kinetics of indirect TPrA oxidation is facilitated on deactivated gold surface. Besides, in situ smoothening of a rough electrode in presence of tandem [Ru(bpy)3]2+/TPrA, the ECL enhancement enables Cu2+ sensing with good reliability and limit of detection. Such atomically smoothened and corrosion-resistant gold surface readily tuned the ECL reactivity and opened new directions on influence of topography and reactivity on ECL mechanisms, thus will be extremely useful for the future development of ECL imaging strategies and highly sensitive ECL sensors.

Highly Regioselective 1,3-Dipolar Cycloaddition of Nitrilimines and Thioaurones Towards Spiro-2-Pyrazolines: Synthesis, Characterization, and Mechanistic Study

In this paper, we report a regiospecific 1,3-dipolar cycloaddition (1,3-DC) reaction of nitrilimines with thioaurone derivatives that afforded the hitherto unreported spiropyrazolines. Spectroscopic and spectrometric data were utilized to confirm the structure of all products and elucidate the reaction’s regiochemistry. A mechanistic study was performed within the Molecular Electron Density Theory (MEDT) at the B3LYP/6-311G(d,p) computational level to explain the regioselectivity observed. The electron localization function (ELF) topological analysis confirms the carbenoid-type (cb-type) mechanism of the cycloaddition reactions between nitrilimines and thioaurones. The intermolecular interactions between reagents in this reaction account for the regioselectivity observed experimentally.

Design of MnOx/TiO2 Nanostructures for Photocatalytic Removal of 2,4-D Herbicide.

The research and modification of semiconductors through different synthesis routes allow obtaining materials with optimal properties to induce new energy levels and improve charge separation efficiency. In this context, the sol-gel method was used to synthesize TiO2-based materials doped with different percentages of MnOx to evaluate their photocatalytic activity in the degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in water under UV irradiation. Characterization results revealed a reduction in crystallite size to 7.2 nm. Adding MnOx enhanced the optical absorption of TiO2, resulting in a shift toward the red end of the spectrum of the forbidden energy band. The photocatalytic activity increased significantly with the percentage of MnOx, reaching a maximum degradation of 70 % in 6 hours with the 3 MnTi material. This increase was attributed to the synthesis method, which facilitated the formation of nanostructured heterojunctions mainly composed of TiO2 and MnO2, reducing the recombination of electron-hole pairs. TEM analysis confirmed these structures. A reaction mechanism for the 3 MnTi material is proposed, considering the mobility of charge carriers and the photooxidation processes of the pollutant.

Nanoporous High Entropy Alloy Al-Pt-Pd-Ru as an Efficient Catalyst for One-Pot Reductive Amination of Nitroarenes.

High entropy alloys (HEAs) are promising heterocatalysts because of their unique physicochemical properties, but research on HEA-catalyzed tandem reactions is lacking. Moreover, limited research on HEAs for molecular transformation has hindered their development. Herein, an unsupported nanoporous HEA Al-Pt-Pd-Ru (HEANPore) prepared using a top-down dealloying method is reported. The Lewis acidity and electron redistribution of the noble metals Pt, Pd, and Ru are identified to be intrinsic of high activity and selectivity of HEANPore in the one-pot reductive amination of nitroarenes. The competitive adsorption of the reactant and corresponding reaction mechanism are investigated using DFT. This study demonstrates the exceptional performance of the HEANPore in tandem reactions, presenting new possibilities for the application of HEAs in the field of catalysis.

Temperature-Controlled Chemoselective Couplings of Alkyl Halides with Disulfides.

An unprecedented, transition metal-free S-alkylation of disulfides with alkyl halides is developed for the first time, providing an efficient and green synthesis of thioethers and even thioesters. Notably, this new method allows the full utilization of both sulfur atoms of disulfides under chemical reductant-free conditions and can be easily scaled up in gram scale, showing good practical value. Control experiments suggested that water, unprecedentedly, serves as the terminal reductant of the whole reaction. Moreover, controllable N-alkyl thiopyridones can be readily obtained at a much lower reaction temperature from the same starting materials, suggesting a kinetic control of N-alkylation vs a thermodynamic control of the S-alkylation process may be involved in the reaction. Interestingly, a halo anion-mediated alkyl group migration from N-alkyl thiopyridones to S-alkyl pyridyl thioethers was observed, suggesting that the reaction may undergo a new and novel reaction mechanism.

Reaction Pathway Regulation for Gaseous and Liquid Products of Electrocatalytic CO2 Reduction under Adsorbate Interactions.

Halide anion adsorption on transition metals can improve the performance of electrochemical CO2 reduction reaction (CO2RR), while the specific reaction mechanisms governing selective CO2RR pathways remain unclear. In this study, we demonstrate for the first time the distinct pathways for gaseous (CO) and liquid products (formate and ethanol) on the well-defined Ag-Cu nanostructures with controlled chlorination, respectively. We show that CO2 conversion to CO on Ag/AgCl can be tuned by adjusting the thickness of AgCl layer, achieving a Faradaic efficiency (FE) near 100% over a broad potential range in a 0.5 M KHCO3 using flow cell. In contrast, the optimized Cl-Ag/Cu system enables the conversion of CO2 into liquid products including formate and ethanol with a total FE nearing 100%, delivering high current density under similar conditions. In situ infrared experiments and theoretical calculations reveal that the lateral adsorbate of *OCHO intermediate facilitates the thermodynamics of both the CO pathway on Cl-Ag(111) and the formate pathway on Cl-Ag/Cu(111) by reducing Gibbs free energy barriers of each potential-limit step. This work uncovers the role of chlorination in the tuning of C-bound or O-bound intermediates during CO2RR on Ag-Cu catalysts, determining the reaction pathway under lateral adsorbate effects.

Combustion Characterization and Kinetic Analysis of Coupled Combustion of Bio-Syngas and Bituminous Coal

The coupled combustion of bio-syngas and bituminous coal is an effective technology to reduce pollutant emissions from coal-fired power plants and improve the utilization rate of biomass energy. However, the effects of bio-syngas blending on bituminous coal combustion characteristics and reaction kinetics remain unclear, restricting the development of bio-syngas and bituminous coal combustion technology. In this study, the experimental studies on the coupled combustion of bio-syngas and bituminous coal under different bio-syngas lower-heating-value-based blending ratio (BLBR) were carried out by Micro-Fluidized Bed Reaction Analyzer (MFBRA), the coupled combustion characteristics and kinetic reaction mechanism of coupled combustion of bio-syngas and bituminous coal were analyzed. The results indicated that the nucleation and growth model (F1 Model) provided a reasonable description of the bituminous coal combustion process on the coupled combustion of bio-syngas and bituminous coal in MFBRA. The blending of bio-syngas significantly reduces the apparent activation energy and pre-exponential factor of bituminous coal combustion reaction. In particular, when the BLBR is 5, 10, 20, and 30%, the apparent activation energy is 48.70, 45.45, 46.75, and 42.35 kJ·mol−1, and the pre-exponential factor is 9.26, 7.10, 8.95, and 6.70 s−1, respectively. This research is helpful for improving the coupled combustion efficiency and ensuring the efficient operation of the coupled combustion system.