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Biomass-derived ethanol (EtOH) and acetaldehyde (AcH) conversion to 1,3-butadiene (1,3-BD) is an alternative process for 1,3-BD production. The present investigation reports the preparation and characterization of isolated La sites introduced into the silanol nests in DeAlBEA as well as detailed studies of the mechanism and kinetics for the conversion of an EtOH-AcH mixture to 1,3-BD. La sites supported on DeAlBEA are found to be present as (≡SiO)2La-OH groups that are H-bonded with adjacent Si-OH groups, possessing high C-C coupling activity and stability, superior to state-of-the-art Y-DeAlBEA. La sites supported on silica (La-SiO2) with a similar chemical structure but no H-bonding interaction with Si-OH groups were prepared for comparison. Lewis acid La sites promote AcH aldol condensation, and the activity of such sites is nearly identical for both La-DeAlBEA and La-SiO2. The rate of C4 product formation increases by a factor of 4.8 upon addition of EtOH to the feed of AcH over La-DeAlBEA, whereas that over La/SiO2 remains unchanged. Investigation of the mechanism and kinetics of AcH aldol condensation and EtOH-AcH conversion to 1,3-BD revealed two C-C bond forming pathways─AcH aldol condensation by Lewis acid La sites and direct coupling of EtOH-AcH over H-bonded (≡SiO)2La-OH···HO-Si≡ sites. This study provides important information about the role of the local environment of isolated Lewis acid sites and their effects on the direct coupling of EtOH and AcH to form 1,3-BD.

ABSTRACT In this work, the mechanistic investigation on the cobalt‐catalyzed CH functionalization of O‐acyl oxime and verification of the origin of selectivities are employed using the density functional theory (DFT) method. Based on the calculations, the most energetically favorable pathway contains four steps: coordination of Co(III) species to the O‐acyl oxime, para‐selective CH activation to give a five‐membered cobaltacycle, [2,1]‐alkyne insertion, and redox‐cyclization to give the final product and regenerate the Co(III) species. IRC calculations clearly indicate that the redox‐cyclization process occurs in a concerted but highly asynchronous manner. The structural analysis reveals that the para‐CH activation occurs preferentially mainly due to the less steric hindrance. FMO analysis and energetic span model are used to disclose the origin of regioselectivity and chemoselectivity, respectively. [ABSTRACT FROM AUTHOR]

Fireproof sealant is a common sealing material and has a wide range of applications, which has the dual performance of sealing and fireproof. To figure out its thermal degradation behavior, the thermogravimetric experiments combined with Fourier transform infrared technology were conducted at multiple heating rates. The results showed that the pyrolysis process could be separated into three stages and the explicit reaction equations were revealed corresponding to each stage: First, ammonium polyphosphate decomposed to produce a large amount of inorganic acid, along with a small amount of ammonia and water. Then, a large amount of ammonia gas was produced from melamine decomposition, and the substrate including acrylic resin began to react. Furthermore, the remaining base materials and intermediate carbonized materials continued to be decomposed to produce large amounts of carbon dioxide, water and residue. The experimental results indicated that the various components of fireproof sealant could cooperate closely and played a synergistic role in flame retardant, which could be an important reference value for guiding the improvement of fire sealing materials. [ABSTRACT FROM AUTHOR]

[Display omitted] The CO preferential oxidation reaction (CO-PROX) is an effective strategy to remove residual poisonous CO in proton exchange membrane fuel cells, in which oxygen vacancies play a critical role in CO adsorption and activation. Herein, a series of CuO/CeO 2 catalysts derived from Ce-MOFs precursors were synthesized using different organic ligands via the hydrothermal method and the CO-PROX performance was investigated. The CuO/CeO 2 -135 catalyst derived from homophthalic tricarboxylic acid (1,3,5-H 3 BTC) exhibited superior catalytic performance with 100 % CO conversion at a relatively low temperature (T 100% = 100 °C), with a wide reaction temperature range and excellent stability. The superior catalytic properties were attributed to the structural improvements provided by the 1,3,5-H 3 BTC precursors and the promotional effects of oxygen vacancies. Additionally, in-situ Raman spectroscopy was performed to verify the dynamic roles of oxygen vacancies for CO adsorption and activation, while in-situ DRIFTS analysis revealed key intermediates in the CO-PROX reaction, shedding light on the mechanistic aspects of the catalytic process. This work not only demonstrates insights into the effective CuO/CeO 2 catalysts for CO preferential oxidation, but also provides a feasible way to synthesize MOF-derived catalysts. [ABSTRACT FROM AUTHOR]

Aromatization of biofuran offers promising approaches for sustainable biochemical production. However, this process is often hampered by low yields and severe coking on traditional zeolite catalysts. Herein, we report co‐feeding CO2 for 2‐methylfuran (MF) aromatization (CCMA) over bifunctional ZSM‐5 supported ZnMoO4. This bifunctional catalyst can achieve both MF and CO2 conversions of >97 %, generating >85 % carbon yield of target arenes and CO with negligible alkenes (0.05 %). Meanwhile, coke formation is remarkably suppressed from 22.3 % to 8.6 %. ZnMoO4/ZSM‐5 is capable of selectively manipulating the reaction intermediates and pathways of the CCMA reactions, favoring the cyclopentenones‐ and alkenes‐based dehydro‐aromatization rather than the benzofurans‐based pathway. This finding challenges the prevailing understanding that MF aromatization follows a hydrocarbon pool mechanism. Moreover, the abundant surface oxygen vacancies of ZnMoO4 facilitate the adsorption of CO2 and its subsequent reaction with coke. These insights into reaction mechanism and catalyst design for co‐conversion of CO2 and biofuran can offer guidelines for process intensification in biomass utilization with a carbon‐negative manner. [ABSTRACT FROM AUTHOR]

For exploring the reaction between the hydroxyl groups of lignin and boric acid under the alkaline condition, we study three proposed mechanisms for the formation of the anionic borate diester (ABDE) using the salicyl alcohol anion as the model compound by the density functional theory. ABDE has high flame retardancy and is a potentially practical application of lignin. The catalysis of sodium cation is found to enhance the deprotonation of the water cluster. The deprotonated product, hydroxide anion, is essential to the critical step, which is the cleavage of B−O bonds of the boric acid molecule, in reaction mechanisms. The energy profiles of the mechanisms show that the reaction between lignin and boric acid may start from the hydroxymethyl moieties of lignin since it requires less energy for the aforementioned critical step than from the phenol moieties of lignin. Moreover, the hydroxide anions compete with the hydroxymethyl groups in lignin for the formation of B−O bonds by forming tetrahydroxyborate anion (TBA) which requires very high activation energies to further react to the desired product ABDE. The optimal condition is to enhance the catalytic effect of sodium cations and meanwhile to control the formation of TBA. [ABSTRACT FROM AUTHOR]

AbstractThis study addresses the often-overlooked chemistry of germanium compared to the extensively researched carbon and silicon. Using advanced DFT methods, we investigated the thermal decomposition of germolane (germacyclopentane). The suggested mechanisms include a 1,2-H shift and 1,1-H2 elimination to form a pentacyclic germylene (1λ2-germolane). The other pathway involves a stepwise [3 + 2] cycloreversion to form a diradical followed by ethene and germirane. Under M062X/def2-TZVP level of theory, the activation barriers in terms of Gibbs energy (ΔG‡298) for the 1,2-H shift and 1,1-H2 elimination pathways were 240.9 and 236.3 kJ/mol, respectively. The reaction energies (ΔG°298) for the initiative steps in the 1,2-H shift and 1,1-H2 elimination mechanisms were 102.9 and 96.2 kJ/mol, indicating a thermodynamic and kinetic competition between the two routes. Temperature dependence analysis from 300 to 1200 K reveals that the 1,1-H2 elimination dominates at higher temperatures and is expected to become spontaneous above 1000 K. [ABSTRACT FROM AUTHOR]

Electrocatalysis can synthesize kinds of valuable chemicals and plays vital role in developing clean and renewable energy storage and conversion devices. In the traditional electrocatalytic systems, researchers try to synthesize one type of valuable chemical at cathode or anode independently. Recently, electrocatalytic bipolar synthesis of valuable chemicals at both cathode and anode simultaneously becomes popular and attracts much attention. In this minireview, we summarize the latest processes on innovative strategies for electrocatalytic bipolar synthesis of various chemicals. We will discuss the findings according to the categories of the products, including bipolar hydrogen production, bipolar formate production and bipolar hydrogenation. And the associated catalysts optimization, reaction mechanism, and design principles are well introduced. Moreover, the challenges and prospects are highlighted for future developments. This review is timely and will guide others pay more attention to this novel electrocatalytic bipolar synthesis systems. [ABSTRACT FROM AUTHOR]

Selective hydrocracking of polycyclic aromatic hydrocarbons (PAHs) from heavy oils and tar to high‐value chemicals such as benzene, toluene, and xylene (BTX) is a promising technology. Due to the lack of comprehensive and rational understanding of the reaction mechanisms, the development and preparation of catalysts and the improvement of catalysis technology are rarely carried out. Since zeolites as crucial solid acid catalyst components in catalytic hydrocracking of PAHs are indispensable, this review systematically analyzed the mechanisms and research advances in hydrogenation, isomerization, and ring‐opening (cracking) on zeolite catalysts. Efficient zeolite catalysts for hydrocracking should have appropriate pore structures for the required diffusivity for reactants and products to avoid secondary polymerization and coke formation, an ideal distribution and strength of acid sites for the formation of the desired carbocation intermediates to achieve the selectivity of products and precisely tunable metal to acid functions to control the competition between (de)hydrogenation and ring‐opening reactions leading to the facilitation of the reaction mechanisms for the desired products. This poses challenges for the research and development of industrial relevant zeolite catalysts. [ABSTRACT FROM AUTHOR]

After a coal seam is mined, the oxidized coal left in its goaf is prone to water immersion, and spontaneous combustion accidents involving water-immersed coal may easily occur when mining the underlying coal seam. Using scanning electron microscopy and nitrogen adsorption experimental methods, the physical structure of high-temperature pre-oxidized water-immersed coal samples was characterized. By means of infrared spectroscopy, electron spin resonance (ESR) and simultaneous thermal analysis, the microscopic characteristics of the coal samples and the endothermic and exothermic characteristics of the oxidative combustion process were studied. The results showed that a specific pre-oxidation soaking time generated more oxidation pores in the coal sample, causing more water to become trapped in the pores and increasing the secondary oxidation heat absorption. High-temperature oxidation promoted the conversion of coal sample functional groups (FG) and free radical active sites, Water immersion led to the formation and loss of FG, and the longer the water immersion time was, the greater the loss. The larger average pore size of the pre-oxidized water-immersed coal sample provided more coal-oxygen contact sites, and the breaking of chemical bonds in the FG during the secondary oxidation process accelerated the heat release and promoted the oxidative re-ignition of the coal sample. The spontaneous combustion of water-immersed coal in the goaf can be prevented by controlling the high oxidation temperature and water immersion time. [ABSTRACT FROM AUTHOR]

Commercial SSZ‐13 zeolite with different n(Si)/n(Al) ratios and from different suppliers were subjected to a post‐synthetic treatment in order to create mesopores of up to 15 nm. Furthermore, the materials were modified with copper ions and thoroughly physico‐chemically characterized. The modified textural properties varied the nature of copper species, and thus, activity in the selective catalytic reduction of NOx with ammonia (NH3‐SCR‐DeNOx). Pulsed‐field gradient nuclear magnetic resonance (PFG‐NMR) studies with hexane as probe liquid revealed improved intracrystalline diffusion for some Cu‐containing SSZ‐13 materials. The NH3‐SCR‐DeNOx pathways are verified via in situ DR UV‐Vis, in situ FT‐IR and EPR, temperature‐programmed studies as well as SSITKA studies that provide a mechanistic understanding of the reaction. Kinetic modelling results demonstrate the highest NH3‐SCR‐DeNOx reaction rates and up to 20 % lower energy barriers with n(Si)/n(Al) ratio of 6.5 for all modified forms (i. e., (NH4)Cu‐SSZ‐13_6.5 and Cu‐SSZ‐13_6.5_NaOH/0.1) and cause only negligible parasitic ammonia oxidation. The modelling of the stop‐flow experiments further demonstrates that the SCR pathway via the HONO surface intermediate is present but barely contributes to the overall NO conversion compared to the dominant path between adsorbed NH3 and NO from the gas phase. [ABSTRACT FROM AUTHOR]

The activation of Cu‐zeolite catalysts is accompanied by an autoreduction reaction, in which a part of Cu(II) species is spontaneously reduced to Cu(I) species. The stoichiometry of autoreduction in which the release of one O2 is accompanied by the reduction of four Cu(II) to Cu(I) has been proposed, but the detailed mechanism of this autoreduction remains unclear. In this work, we used DFT calculations to study the autoreduction mechanism in Cu‐CHA zeolites. The two reduction mechanisms of [CuOH]+ to Cu+ in CHA‐type zeolite were systematically studied. In Mechanism I, two [CuOH]+ react via dehydration to form [Cu−O−Cu]2+, and the further reaction of two [Cu−O−Cu]2+ to produce O2 is the most critical step, which requires four charge‐compensating framework Al in close proximity. In Mechanism II, the production of O2 occurs via [CuO]+ intermediates, and the generation of possible [CuO]+ is the most critical step. The exploration of autoreduction reactions in a variety of Cu‐CHA models with different Al sittings shows that the O−O distances between two intermediate precursors, i. e., two [Cu−O−Cu]2+ in Mechanism I, or two [CuO]+ in Mechanism II, are key factors determining the activation barriers of O2 production during autoreduction. [ABSTRACT FROM AUTHOR]

Organo‐aluminum compounds are usually derived via salt metathesis reactions starting from aluminum halides and s‐block organometallics such as organolithiums or Grignard reagents. Herein, an alternative route is reported using an Cp*Al(I)/Zn(II)R2 (Cp* = C5Me5; R = aryl) system which facilitates the formation of a range of halide and donor free heteroleptic triorgano‐alanes of the general formula [Al(Cp*)R2]. Exposing the obtained alanes to an atmosphere of CO2 enables for the selective insertion of CO2 in their AlCp* moieties. State of the art quantum chemical calculations support experimental observations providing mechanistic insights on the observed reactivity of the [Al(Cp*)R2] compounds towards this unsaturated organic molecule. [ABSTRACT FROM AUTHOR]

The reaction between aldehydes or ketones and alkynes—the carbonyl‐alkyne metathesis—constitutes a very useful strategy for the synthesis of α,β‐unsaturated carbonyls. We now demonstrate that iodine is a highly efficient catalyst for both the intra‐ and intermolecular metathesis reaction in very small concentrations (0.1–1 mol %). Our protocol outperforms other catalytic systems, is operationally very simple, cheap, metal‐free, and tolerates a large variety of functional groups (e. g. −CN, −CO2Me, −Br, −OH) at very low catalyst loadings. We can furthermore show that iodine‐catalyzed carbonyl‐alkyne metatheses can be combined with other iodine‐catalyzed reactions in one‐pot procedures to afford larger and more complex molecular structures. Finally, our mechanistic studies indicate that the iodonium ion is the active catalyst under the reaction conditions. [ABSTRACT FROM AUTHOR]

The α-oxyalkylation of aryl chlorides with ethers and alcohols using a small amount of a peroxide was found to be induced by photoirradiation. The reaction proceeds through a homolytic aromatic substitution (HAS) mechanism consisting of addition of an α-oxyalkyl radical to an aryl chloride and elimination of the chlorine atom to give the α-oxyalkylation product, where photoirradiation is considered to effect not only the initiation step to facilitate homolysis of a peroxide, but also the propagating radical chain. [ABSTRACT FROM AUTHOR]

Context: The negative of the Shannon entropy derivative is proposed to account for electron density contraction as the chemical bonds are breaking and forming during a chemical reaction. We called this property the electron density contraction index, EDC, which allows identifying stages in a reaction that are dominated by electron contraction or expansion. Four different reactions were analyzed to show how the EDC index changes along the reaction coordinate. The results indicate that the rate of change of Shannon entropy is directly related to the rate of change of the electron density at the bond critical points between all the atomic pairs in the molecular systems. It is expected that EDC will complement the detailed analysis of reaction mechanisms that can be performed with the theoretical tools available to date. Methods: Density functional theory calculations at the B3LYP/6-31G(d,p) level of theory were carried out using Gaussian 16 to analyze the reaction mechanisms of the four reactions studied. The reaction paths were obtained via the intrinsic reaction coordinate method, which served as the reaction coordinate to obtain the reaction force and the EDC profiles in each case. Shannon entropy and electron density at the bond critical points were calculated using the Multiwfn 3.7 package. [ABSTRACT FROM AUTHOR]

Two novel complexes were synthesized by the reaction of benzothiazol‐pyrimidin‐2‐ylidene ligand (BTP) with Pd (II) and Fe (III) ions. A variety of various spectral and analytical methods (infrared, 1H/NMR, 13C/NMR, electronic spectra, CHN analyses, mass spectra, thermogravimetric analysis, and magnetic susceptibility) were used to characterize the investigated BTP ligand and its complexes. Correlation of experimental results with density functional theory calculation proves that the geometry of BTP‐Fe complex is octahedral, whereas BTP‐Pd complex is square planner. The catalytic effectiveness of BTP complexes were tested for three‐component condensation process under moderate and environmentally friendly reaction conditions. Moreover, the effects of different Lewis acid, basic, and ionic liquid catalysts, as well as solvent and catalyst dose on the catalytic reaction were investigated. Both catalysts demonstrated strong catalytic capability in the carefully regulated ideal reaction circumstances. Heterogeneous catalyst BTP‐Pd exhibited superior catalytic performance compared to homogeneous catalyst BTP‐Fe. All products were obtained in high TOF (turnover frequency) numbers in the presence of these catalysts, which indicate the high efficiency of these catalysts in the synthesis of dihydro‐7H‐5‐thia‐hexaaza‐s‐indacen‐6‐one derivatives. Moreover, the two catalysts' recycling and reusability in reactions were also investigated. Heterogeneous BTP‐Pd catalyst could be reused up to seven times with high efficiency, but the homogeneous catalyst (BTP‐Fe) could only be recycled up to four times. Furthermore, the mechanism of catalytic reaction was suggested and supported by DFT calculation. The simplicity, safety, stability, use of commercially available catalysts, quick reaction times, and excellent yields make it promising for future industrial use. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO X catalysts with tunable morphology and oxygen vacancy defects were prepared. • Tailoring the morphology of MnO X can greatly improve the catalytic activity. • The oxygen vacancy defect on MnO X can expedite the activation-oxidation of toluene. To clarify the key role of oxygen vacancy defects on enhancing the oxidative activity of the catalysts, metal–organic frameworks (MOFs) derived MnO X catalysts with different morphologies and oxygen vacancy defects were successfully prepared using a facile in-situ self-assembly strategy with different alkali moderators. The obtained morphologies included three-dimensional (3D) triangular cone stacked MnO X hollow sphere (MnO X -H) and 3D nanoparticle stacked MnO X nanosphere (MnO X -N). Compared to MnO X -N, MnO X -H exhibited higher activity for the oxidation of toluene (T 90 = 226 °C). This was mainly due to the large number of oxygen vacancy defects and Mn4+ species in the MnO X -H catalyst. In addition, the hollow structure of MnO X -H not only facilitated toluene adsorption and activation of toluene and also provided more active sites for toluene oxidation. Reaction mechanism studies showed that the conversion of toluene to benzoate could be realized over MnO X -H catalyst during toluene adsorption at room temperature. In addition, abundant oxygen vacancy defects can accelerate the activated oxidation of toluene and the formation of oxidation products during toluene oxidation. [ABSTRACT FROM AUTHOR]

Emerging contaminants (ECs) are widely present in aquatic environments, posing potential risks to both ecosystems and human health. The ultrasound-assisted persulfate oxidation process has attracted considerable attention in the degradation of ECs due to its ability to generate both sulfate radicals and cavitation effects, enhancing degradation effects. In this paper, the principle of ultrasonic synergistic Fenton-like oxidation system for degrading organic pollutants was reviewed, divided into homogeneous system, non-homogeneous system, and single-atom system to explore the synergistic effect of ultrasound-enhanced persulfate technology in three aspects, and the effects of environmental factors such as ultrasonic frequency and power, system pH, temperature, and initial oxidant concentration on the system's decontamination performance were discussed. Finally, future research on ultrasonically activated persulfate technology is summarized and prospected. [ABSTRACT FROM AUTHOR]

Some pathogens use heme‐containing nitric oxide reductases (NORs) to reduce NO to N2O as their defense mechanism to detoxify NO and reduce nitrosative stress. This reduction is also significant in the global N cycle. Our previous experimental work showed that Fe and Co porphyrin NO complexes can couple with external NO to form N2O when activated by the Lewis acid BF3. A key difference from conventional two‐electron enzymatic reaction is that one electron is sufficient. However, a complete understanding of the entire reaction pathways and the more favorable reactivity for Fe remains unknown. Here, we present a quantum chemical study to provide such information. Our results confirmed Fe's higher experimental reactivity, showing advantages in all steps of the reaction pathway: easier metal oxidation for NO reduction and N−O cleavage as well as a larger size to expedite the N/O coordination mode transition. The Co system, with a similar product energy as the enzyme, shows potential for further development in catalytic NO coupling. This work also offers the first evidence that this new one‐electron NO reduction is both kinetically competitive and thermodynamically more favorable than the native pathway, supporting future initiatives in optimizing NO reduction agents in biology, environment, and industry. [ABSTRACT FROM AUTHOR]

Synthesis of renewable isoprene continues to attract significant interest, yet catalysts still need improvement for industrial applications. We report herein an efficient and novel Prins tandem approach for highly selective production of isoprene from bio‐based methanol and isobutene over Mo‐Fe−O and MgO/Mg(OH)2 acid‐base bifunctional catalysts. Hydration decreases the number of strong basic sites O2− ions and increases OH groups over MgO, thus improving the isoprene selectivity. Basic OH on Mg(OH)2 promotes the Prins condensation of formaldehyde and isobutene, while acidic OH promotes dehydration of isoprenol to isoprene. Suitable contents and proportions of basic and acidic OH groups over Mg(OH)2 increase isoprene selectivity and methanol conversion to 90 and 92 % on the Mo‐Fe−O+Mg(OH)2 composite catalysts, respectively. It exhibits good recycling stability, with isoprene selectivity remaining 90 % after five successive regenerations. DFT calculations reveal OH groups formed after hydration reduce the energy barrier of the H transfer step, thereby promoting the overall reaction. [ABSTRACT FROM AUTHOR]

ε‐Caprolactam (CPL) is industrially produced by Beckmann rearrangement of cyclohexanone oxime (CHO) under fuming sulfuric acid, resulting in corrosive and environmental issues. Herein, we prepared triethylamine hydrochloride (TEAHC) and ZnCl2 formed deep eutectic solvent (DES) [TEAHC:2ZnCl2] with Brønsted and Lewis acid sites for efficient liquid rearrangement, achieving 100% conversion of CHO and 95.5% yield of CPL at 80 °C for only 1 h. The results show that ZnCl2 in [TEAHC:2ZnCl2] can promote the detachment of proton, which acts as Brønsted acid site combined with another ZnCl2 molecule to synergistically catalyze the reaction. In the Brønsted acid catalyzed process, the nitrogen atom in CHO as reactive site can be readily attacked by the proton to form protonated CHO, which subsequently undergoes rearrangement. By adding ZnCl2 into TEAHC to obtain [TEAHC:2ZnCl2], the formation of ZnCl2‐CHO complex results in a significant reduction in reaction energy barrier through synergistic effect of Brønsted and Lewis acids. Particularly, the fitted reaction kinetics and low activation energy also confirm the rearrangement can occur under low reaction temperature. Thus, the DESs with efficient catalytic performances for ketoxime rearrangements provide a potential method to design active sites for Beckmann rearrangements of oximes under mild reaction conditions. [ABSTRACT FROM AUTHOR]

This study is focused on examining the incorporation of oxidative dehydrogenation into the aromatization of ethane, utilizing thermodynamic analysis and catalytic experiments. The catalysts were characterized by inverse temperature programmed reduction, X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD). The results indicated that a blend of the M1 catalyst, containing oxides of vanadium, niobium, and tellurium, with H‐ZSM‐5, serves as an effective catalyst system for the oxidative aromatization of ethane at T = 380 °C. The M1's role in the oxidative dehydrogenation of ethane contributes to de‐bottlenecking the essential step of the reaction. On the zeolitic catalyst aromatic compounds are formed from a surface hydrocarbon pool. In parallel, the oxidation of these intermediates was observed. Also, the formation of paraffins through H‐transfer was evident from the catalytic results. Although the zeolite underwent significant deactivation due to coking, the M1 catalyst demonstrated highly stable activity. Interestingly, the system did not show any synergistic effects. Based on the structure‐activity relation of the catalytic system a reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

Organic halogen compounds are cornerstones of applied chemical sciences. Halogen substitution is a smart molecular design strategy adopted to influence reactivity, membrane permeability and receptor interaction. Chiral bioreceptors may restrict the stereochemical requirements in the halo‐ligand design. Straightforward (but expensive) catalyzed stereospecific halogenation has been reported. Historically, PCl5 served access to uncatalyzed stereoselective chlorination although the stereochemical outcomes were influenced by steric parameters. Nonetheless, stereochemical investigation of PCl5 reaction mechanism with carbamoyl (RCONHX) compounds has never been addressed. Herein, we provide the first comprehensive stereochemical mechanistic explanation outlining halogenation of carbamoyl compounds with PCl5; the key regioselectivity‐limiting nitrilimine intermediate (8‐Z.HCl); how substitution pattern influences regioselectivity; why oxadiazole byproduct (P1) is encountered; stereo‐electronic factors influencing the hydrazonoyl chloride (P2) production; and discovery of two stereoselectivity‐limiting parallel mechanisms (stepwise and concerted) of elimination of HCl and POCl3. DFT calculations, synthetic methodology optimization, X‐ray evidence and experimental reaction kinetics study evidence all supported the suggested mechanism proposal (Scheme 2). Finally, we provide mechanism‐inspired future recommendations for directing the reaction stereoselectivity toward elusive and stereochemically inaccessible (E)‐bis‐hydrazonoyl chlorides along with potentially pivotal applications of both (E/Z)‐stereoisomers especially in medicinal chemistry and protein modification. [ABSTRACT FROM AUTHOR]

Molybdenum trioxide (MoO3) is a promising positive electrode material for aqueous aluminum‐ion batteries (AAIBs) due to its high theoretical capacity. However, MoO3 faces several challenges in an aqueous electrolyte, such as easy dissolution of reaction products, volume expansion, and low conductivity, which severely limit its application in aqueous batteries. In this work, we effectively increased the overall conductivity of the electrode by in situ growing MoO3 on the Mo2C MXene layer. MXene can effectively inhibit the dissolution and structural loss of MoO3 reaction products. Additionally, the coordination effect of Mo2C and MoO3 achieves a stable near‐surface reaction on the MXene laminates, resulting in the Mo2C/MoO3 composite exhibiting excellent aluminum storage properties (123.5 mAh/g after 200 cycles at 0.4 A/g). The energy storage mechanism of H+/Al3+ co‐insertion/extraction was elucidated through ex situ characterization, and the promotion effect of Mo2C on MoO3 reaction kinetics was verified by density functional theory (DFT) calculations. This work provides new insights into improving the stability of AAIBs cathodes and extends the application of Mo‐based MXene in aqueous batteries. [ABSTRACT FROM AUTHOR]

Aromatic polyketides are pharmaceutically significant natural products. Product template (PT) domains from fungal non‐reducing polyketide synthases (NR‐PKSs) control the regioselective aldol cyclization of highly reactive polyketide intermediates, whose instabilities have hindered experimental studies. The molecular basis of PT‐catalyzed cyclization and aromatization remain ambiguous. Herein, we conducted MD simulations and QM/MM calculations to explore the catalytic mechanHism and the cyclization pattern of PksA PT specific for C4−C9. The cyclization mediated by PksA PT is initiated by the C4 deprotonation followed by the aldol condensation in C4−C9 register. PTs which evolve from ancient PKS dehydratases (DHs) perform dehydration reactions to aromatize the cyclized intermediates. In PksA PT, the catalytic His1345 and Asp1543 are responsible for aldol cyclization and aromatization steps, respectively. A keto‐enol tautomerism at C3 assists in the elimination reaction catalyzed by Asp1543 with a water molecule network, different from most DHs of PKSs. The C2−C7 aldol cyclization in PksA PT can occur, but the subsequent dehydration step is kinetically unfeasible and thermodynamically unfavorable, suggesting that the aromatization steps determine the C4−C9 cyclization mode of PksA PT. Overall, these computational investigations provide detailed mechanistic insights into the regiospecific intramolecular cyclization and aromatization controlled by fungal PksA PT. [ABSTRACT FROM AUTHOR]

Alkynes have been the preferred substrates since the early development of gold catalysis at the dawn of this century. Amongst them, 1‐haloalkynes have gained increased interest in recent years due to the versatility offered by these bifunctional entities as well as the identification of unique reaction modes in this already mature research field. Herein, the seminal contributions that resulted in the observed growth in recent years and the most recent developments will be discussed. [ABSTRACT FROM AUTHOR]

In the present work, WB2–SiC composite powders containing 20 vol.% of SiC were in situ synthesized by the boro/carbothermal reduction with WO3, SiO2, B4C, and carbon black as raw materials at 1400°C, 1500°C, and 1600°C, respectively. The as‐synthesized composite powders were then consolidated by spark plasma sintering (SPS) technique to obtain WB2–SiC composite bulk samples. The experimental results showed that the relative density of the WB2–SiC composite ceramic samples achieved in this study was higher than 97.5%. Also, electronic microscopy observations showed that SiO2 had reacted completely during the preparation process, and the SiC grains were homogenously embedded among the WB2 grains with the formation of a three‐dimensional structure. The Vickers hardness and fracture toughness values of the composite ceramic fabricated by powder heat treated at 1400°C were 24.6 ± 0.7 GPa and 5.4 ± 0.7 MPa·m1/2, respectively, which were the highest among three samples prepared in this study. [ABSTRACT FROM AUTHOR]

The zeolite‐catalyzed methanol‐to‐aromatics (MTA) process is a promising avenue for industrial decarbonization. This process predominantly utilizes 3‐dimensional 10‐member ring (10‐MR) zeolites like ZSM‐5 and ZSM‐11, chosen for their confinement effect essential for aromatization. Current research mainly focuses on enhancing selectivity and mitigating catalyst deactivation by modulating zeolites′ physicochemical properties. Despite the potential, the MTA technology is at a low Technology Readiness Level, hindered by mechanistic complexities in achieving the desired selectivity towards liquid aromatics. To bridge this knowledge gap, this study proposes a roadmap for MTA catalysis by strategically combining controlled catalytic experiments with advanced characterization methods (including operando conditions and "mobility‐dependent" solid‐state NMR spectroscopy). It identifies the descriptor‐role of Koch‐carbonylated intermediates, longer‐chain hydrocarbons, and the zeolites′ intersectional cavities in yielding preferential liquid aromatics selectivity. Understanding these selectivity descriptors and architectural impacts is vital, potentially advancing other zeolite‐catalyzed emerging technologies. [ABSTRACT FROM AUTHOR]

A computational study on the intricate mechanism of thiophene ring‐fragmentation (TRF) in the UV photodissociation, dissociative ionization, and dissociative electron attachment process has been performed. The complete fragmentation process is studied using high level G4 composite method for neutral, cationic, and anionic species by elucidating a detailed mechanism for various reaction channels. The study shows that for neutral thiophene, the major pathway is the migration of H atom and subsequent fragmentation through a transition state yielding acetylene (HC≡CH) and H2C=C=S. However, for the thiophene cation, the acetylene (HC≡CH)+H2C=C=S+ channel is a two‐step and barrier less process. The onset of CH3+HC=C=C=S channel has been observed in both the thiophene cation and anion which was absent in the neutral analogue. Similarly, the onset of H2S+HC≡C—C≡CH channel has been found to operate only in the thiophene cation. Others, such as HCS and HS elimination channels have been found in all the species showing similar dissociation mechanism. For the thiophene anion, the TRF process is very much similar to that of thiophene cation. However, the reaction enthalpies of the various elimination channels in the anionic species are lower as compared to that of cationic species. During the study, the ionization energies and electron affinities of various molecules/radicals produced during the fragmentation process of thiophene were also computed. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction technology offers an effective way to convert CO2 into valuable chemicals and fuels, presenting a sustainable solution for carbon emissions. Current electrocatalytic CO2 reduction technologies encounter significant issues such as salt precipitation and hydrogen evolution, which prevent energy conversion efficiency, selectivity, current density, and stability from simultaneously meeting industrial standards. In recent years, researchers have discovered that increasing the CO2 pressure on the gas supply could enhance the coverage of the catalyst and activate more CO2 reduction reaction sites on the catalyst surface, which provides a practical and effective approach for optimizing the energy conversion and mass transfer. In this review, we provide a comprehensive review of the development history and current status of high-pressure CO2 electrocatalytic reduction technology, focusing on its reaction devices, catalytic performance, and reaction mechanisms. Furthermore, we summarize and offer insights into the most promising research avenues to propel the field forward. Highlights: 1. A briefly discussion on the challenges faced by CO2 electrochemical reduction. 2. The state-of-the-art progress of the high-pressure CO2 electrochemical reduction for chemical synthesis is summarized. 3. The bottlenecks of current high-pressure CO2 electrochemical reduction technology are highlighted and potential optimization strategies are proposed. [ABSTRACT FROM AUTHOR]

When a poly(vinyl chloride) (PVC) wire experiences overload failure, the internal structure of the insulation changes to become overloaded insulation and the fire hazard changes. In this study, the thermo‐oxidative degradation behavior of new and overloaded PVC insulation materials was analyzed using coupled thermogravimetric‐Fourier transform infrared spectroscopy (TG‐FTIR). The thermo‐oxidative degradation results show that the first two stages of thermo‐oxidative degradation of PVC insulation are important stages for measuring fire hazard. In addition, the onset temperature of thermo‐oxidative degradation of overloaded PVC insulation was increased. The activation energies of the first two stages of the overloaded PVC insulation increased by 7.7% and 27.0%, respectively, compared to the new PVC insulation. And the reaction mechanism is changed. The FTIR results indicate that the increased amount of volatile organic compounds and CO2 generated during the pyrolysis of the overloaded PVC insulation may result in the generation of more heat and smoke during combustion, thus increasing the fire hazard. [ABSTRACT FROM AUTHOR]

Electrochemical reactions are very complex and involve a variety of physicochemical processes. Accurate and systematic monitoring of intermediate process changes during the reaction is essential for understanding the mechanism of electrochemical reactions and is the basis for rational design of new electrochemical reactions. On‐line electrochemical analysis based on mass spectrometry (MS) has become an important tool for studying electrochemical reactions. This technique is based on different ionization and sampling means and realizes on‐line analysis of electrochemical reactions by establishing electrochemistry‐MS (EC‐MS) coupling devices. In particular, it provides key evidence for elucidating the reaction mechanism by capturing and identifying the reactive reaction intermediates. This review will categorize various EC‐MS devices and the organic electrochemical reaction systems they study, highlighting the latest research progress in recent years. It will also analyze the properties of various devices and look forward to the future development of EC‐MS. [ABSTRACT FROM AUTHOR]

Bisfunctional benzoxazine and polyether diamine‐based polymers show Arrhenius‐like stress‐relaxation varying with stoichiometry and polymerization temperatures proving vitrimeric behavior. Molecular structural investigations reveal the presence of different aminoalkylated phenols occurring at varying ratios depending on polymer composition and polymerization conditions. The vitrimeric mechanism is found to involve an amine exchange reaction of aminoalkylated phenols in an equilibrium reaction like a nucleophilic substitution reaction. As determined by molecular studies and dissolution experiments in reactive solvents, aliphatic and aromatic primary as well as aliphatic secondary amines in the polybenzoxazine structure can act as nucleophiles in reaction with electrophilic methylene bridges. Thus, aminoalkylated phenols proved to be a relevant structural motif resulting in a vitrimeric polybenzoxazine due to amine exchange reaction. [ABSTRACT FROM AUTHOR]

The carbonyl‐alkyne metathesis reaction is a powerful method for the synthesis of α,β‐unsaturated carbonyls. We now report on the development of a halogen‐bond catalyzed protocol for both the intra‐ and intermolecular reaction. Our studies revealed that methanol is a highly efficient solvent and that a very broad range of functional groups are tolerated under the reaction conditions. Mechanistic studies support the proposed halogen‐bond interaction. Furthermore, the halogen‐bond protocol is compared with other available catalytic systems for these reactions. [ABSTRACT FROM AUTHOR]

A computational mechanistic study was performed to investigate the transfer hydrogenation of styrene catalysed by a potassium tris‐hexamethyldisilazide magnesiate in the presence of 1,4‐cyclohexadiene. Exploiting cooperative effects between Mg and K centres present in this tris(amide) complex results in the selective formation of the desired product ethylbenzene. The calculations demonstrate the synergy of the metal centres within the bimetallic complex, since neither the monometallic potassium amide K(HMDS) nor the magnesium amide Mg(HMDS)2 on their own can efficiently execute this transformation under the experimental conditions. Several distinct mechanistic pathways have been explored, leading to the identification of the most plausible sequence in which both metal centres act in a synchronised manner. [ABSTRACT FROM AUTHOR]

Platinum‐based supported intermetallic alloys (IMAs) demonstrate exceptional performance in catalytic propane dehydrogenation (PDH) primarily because of their remarkable resistance to coke formation. However, these IMAs still encounter a significant hurdle in the form of catalyst deactivation. Understanding the complex deactivation mechanism of supported IMAs, which goes beyond conventional coke deposition, requires meticulous microscopic structural elucidation. In this study, we unravel a nonclassical deactivation mechanism over a PtZn/γ‐Al2O3 PDH catalyst, dictated by the PtZn to Pt3Zn nanophase transformation accompanied with dezincification. The physical origin lies in the metal support interaction (MSI) that enables strong chemical bonding between hydroxyl groups on the support and Zn sites on the PtZn phase to selectively remove Zn species followed by the reconstruction towards Pt3Zn phase. Building on these insights, we have devised a solution to circumvent the deactivation by passivating the MSI through surface modification of γ‐Al2O3 support. By exchanging protons of hydroxyl groups with potassium ions (K) on the γ‐Al2O3 support, such a strategy significantly minimizes the dezincification of PtZn IMA via diminished metal‐support bonding, which dramatically reduces the deactivation rate from 0.2044 to 0.0587 h−1. These findings decode the nonclassical PDH deactivation mechanism over supported IMA catalysts and elaborate a new logic for the design of high‐performance IMA based PDH catalysts with long‐term stability. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculation has been used to reveal palladium‐catalyzed mode of diaziridinone ring activation. Our theoretical studies found that oxidative addition of di‐tert‐butyldiaziridinone to Pd(II) can give a high valent Pd(IV) intermediate, along with the cleavage of N─N bond in di‐tert‐butyldiaziridinone through a concerted three‐membered‐cyclic transition state. Subsequent transformations via reductive elimination and β‐N elimination give the desired indolo[3,2‐b]indole product. The competitive activation modes such as metathesis and migratory insertion can be excluded in our selected model reaction. The rate‐determining step of this reaction is the oxidative addition of di‐tert‐butyldiaziridinone step. Distortion‐interaction analysis was conducted to reveal that the oxidative addition mode of di‐tert‐butyldiaziridinone is superior to the metathesis mode due to the lower interaction energy. [ABSTRACT FROM AUTHOR]

Water oxidation is a crucial reaction in the artificial photosynthesis system. In the present work, density functional calculations were employed to decipher the mechanism of water oxidation catalyzed by a binuclear cobalt complex, which was disclosed to be a homogeneous water oxidation catalyst in pH=7 phosphate buffer. The calculations showed that the catalytic cycle starts from the CoIII,III−OH2 species. Then, a proton‐coupled electron transfer followed by a one‐electron transfer process leads to the generation of the formal CoIV,IV−OH intermediate. The subsequent PCET produces the active species, namely the formal CoIV,V=O intermediate (4). The oxidation processes mainly occur on the ligand moiety, including the coordinated water moiety, implying a redox non‐innocent behavior. Two cobalt centers keep their oxidation states and provide one catalytic center for water activation during the oxidation process. 4 triggers the O−O bond formation via the water nucleophilic attack pathway, in which the phosphate buffer ion functions as the proton acceptor. The O−O bond formation is the rate‐limiting step with a calculated total barrier of 17.7 kcal/mol. The last electron oxidation process coupled with an intramolecular electron transfer results in the generation of O2. [ABSTRACT FROM AUTHOR]

The emergence of low temperature plasma technology provides a new idea for reforming methane and carbon dioxide・ This paper describes the basic principle of low temperature plasma co-catalyzing CH4-CO2 reforming and generating synthesis gas (CO and H2) of high valuechemicals, explores the reaction mechanism of low temperature plasma co-catalyzing CH4-CO2 reforming, and analyzes the action mechanism of low temperature plasma in the collaborative catalytic CH4-CO2 reforming reaction・ The effects of the active components, support and additives on the reforming reaction of CH4-CO2 were discussed, and the influencing factors and existing problems in the process of low temperature plasma co-cat ・ alyzed reforming reaction were reviewed. [ABSTRACT FROM AUTHOR]

Combustible gases, such as CO, CH4, and H2, are produced during spontaneous coal combustion in goaf, which may cause an explosion under the stimulation of an external fire source. It is of great significance to study the influence of combustible gases, such as CO and H2, on the characteristics of a gas explosion. In this study, CHEMKIN software (Version 17.0) and the GRI-Mech 3.0 reaction mechanism were used to study the influences of different concentration ratios between CO and H2 on the ignition delay time, free radical concentration, and key reaction step of a gas explosion. The results show that the increase in the initial CH4 and CO concentrations prolonged the ignition delay time, while the increase in the H2 concentration shortened the time and accelerated the explosion reaction. The addition of H2 promoted the generation of free radicals (H·, O·, ·OH) and accelerated the occurrence of the gas explosion. CO generated ·OH free radicals and dominated the methane consumption through the R119 and R156 reactions. As the concentrations of CO and H2 increased, the R38 reaction gradually became the main driving factor of the gas explosion. [ABSTRACT FROM AUTHOR]

Formaldehyde (HCHO), which is one of the common pollutants in indoor environment and industrial processes, can cause adverse effects on human health. The thermal catalytic oxidation technology is regarded as the most promising approach due to its easy handling and environmental friendliness. This article reviews the current status of the catalytic oxidation of HCHO over noble metal and transition metal oxide catalysts. The general feature and the reaction mechanism of the catalytic oxidation of HCHO are summarized first. Based on the discussion of the reaction mechanism, the influence of some factors (catalyst preparation process, catalyst support, promoter and morphology) on the activity of the catalyst have been addressed. The structure of the catalysts has been elucidated and correlated with the reaction mechanism as well as the catalytic performance. Finally, the perspectives for the catalytic oxidation of HCHO in future research are presented. Hopefully, this review can shed light on the design of more active catalysts for HCHO oxidation to realize their practical application. [ABSTRACT FROM AUTHOR]

A detailed mechanistic probe of the organolanthanide‐mediated tandem insertion/annulation of alkynylbenzonitriles with secondary amines by an archetypical homoleptic lanthanum silylamide starting material is presented. An in‐depth computational scrutiny of alternatively plausible pathways for relevant productive steps and also performance‐degrading pathways identified the pathway likely traversed in productive catalysis. It entails the transformation of the starting material into various of silylamide/amide compounds, of which the lanthanum bis‐silylamide/amide is thermodynamically prevalent, capable of promoting the process. Benzonitrile insertion is irreversible to readily afford the lanthanum amidinate, which can adopt various easily interconvertible ligation pattern. The rather rapid protonolysis of the La─N imine linkage would lead to undesirable aminoamidines, but its net endergonicity renders this performance‐degrading avenue nonviable. Instead, the lanthanum amidinate is converted back into catalytically competent lanthanum bis‐silylamide/amide with the release of the observed aminoisoindole product. This transformation favors a stepwise insertative cyclisation/La─C alkenyl protonolysis sequence over an otherwise kinetically noncompetitive proton‐triggered stepwise N─C/C─H bond forming process. The operative insertative pathway comprises turnover‐limiting and irreversible insertion of the alkyne C≡C tether into the La─N amidinate linkage followed by La─C alkenyl aminolysis at the intervening lanthanum alkenylisoindinyl intermediate. The DFT‐assessed barrier for turnover‐limiting insertative N─C ring closure favorably compares with reported performance data. [ABSTRACT FROM AUTHOR]

Organic liquid hydrogen storage is a promising hydrogen storage method.Studying the catalytic mechanism of hydrogen storage-release at the atomic level is an important way to find efficient and low-cost catalysts.The reaction mechanism of stepwise dehydrogenation of methylcyclohexane (MCH) to toluene under the catalysis of transition metal dimer ion Ni Ti+was studied by density functional theory (DFT) method,and the energy changes of reactants,intermediates and products were investigated.The wave function analysis method was used to observe the change of atomic charge during the reaction,and the properties such as the density of states (DOS) of the initial compound were analyzed.The results show that the reaction between Ni Ti+and methylcyclohexane is an exothermic reaction on the mixed potential energy surface.The three dehydrogenation molecular mechanisms are similar.The overall exothermic heat of the reaction is-12.19 kcal·mol-1.The intermediates methylcyclohexene and methylcyclohexadiene were obtained,which were consistent with the experimental results.The rate-determining step of the whole reaction is IM10→TS10 during the third dehydrogenation reaction. [ABSTRACT FROM AUTHOR]

The synthesis of hollow AlN microsphere was studied because of its potential applications in various areas associated with high surface area and lightweight. A combined technique of hydrothermal and carbothermal reduction–nitridation (CRN) was adopted to synthesize spherical precursor and to transform to AlN, respectively, using Al-nitrate, sucrose, and urea. The precursor having different morphology were obtained after hydrothermal treatments at 180 °C for 12 h, depending on starting material combinations, where urea/Al molar ratio = 1 resulted in amorphous hollow microsphere. By CRN at 1500 °C for 4 h in a flowing N 2 atmosphere, approximately 5 μm-sized hollow microsphere composed of AlN, α -Al 2 O 3 , or γ -AlON could be synthesized. CRN at higher temperature (1600 °C for 4 h) or for longer holding time (1500 °C for 10 h) is required to obtain pure AlN microsphere. Further tests at nine different hydrothermal conditions were performed to find an optimal synthesis condition, while the possible formation mechanism for hollow AlN microspheres was also proposed based on observations. [ABSTRACT FROM AUTHOR]

Waste sulphur produced in industrial processes is often exposed to the air, and its diffusion and combustion in the environment can produce harmful substances, posing a significant risk to ecological safety and human health. Herein, a novel method for the direct treatment of solid sulphur with manganese dioxide based on a simple sealed reactor is proposed. Significantly, the developed sulphur treatment technology could prepare high purity manganese sulphate at the same time. Under the optimum conditions of the reaction temperature of 187.2°C, reaction time of 21.6 h, sulphuric acid loading of 1.00 mol ∙ L−1, and manganese dioxide dosage of 4.00 mol ∙ mol‐S−1 derived by the response surface method (RSM), the removal efficiency of sulphur could reach near 100%, and the purity of the manganese sulphate product obtained was more than 98%. Kinetic model fitting analysis and several characterization methods were adopted to confirm that the reaction process between sulphur and manganese dioxide follows the unreacted nuclear model controlled by surface chemical reaction, and the transformation paths of Mn and S elements were proposed. This study provides a novel method for the resource treatment of waste sulphur and the preparation of high purity manganese sulphate. [ABSTRACT FROM AUTHOR]

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The present study explores the bioenergy potential of animal manure based on the physicochemical and thermogravimetric analysis. This study examines the thermal degradation behaviour of cattle manure using different model-free approaches. Further, the artificial neural network (ANN) was used to train the recorded TGA data. The average activation energy was 159.47, 158.08, 159.89, 158.66, 158.36, and 161.65 kJ/mol using FWO, KAS, Friedman, Starink, Tang, and Boswell methods. Further, Criado master plots were also used to determine the reaction mechanism, and the Coats–Redfern (CR) method was used for the multi-component modelling. The best fit of the model was R2 of 0.990 at a heating rate of 20 °C/min as compared to other heating rates. R2 was determined to be the most appropriate mechanism at all heating rates, and it represents the second-order random nucleation. The several mechanisms that best fit the experimental data at 20 °C /min are as follows: R2 > R1.5 > D5 > R2.5 > R1 > N1.5 > R3 > N2 > D3 > G2 > R3.25 > D4 > N3 > R0.5 > D2 > R4 > D1 > N4 > P2/3 > R0. Also, activation energies were calculated from six different iso-conversional methods to determine the effect on thermodynamic parameters, namely, enthalpy, Gibbs free energy, and entropy change during the pyrolysis of cattle manure. This study develops an ANN-predicted modelling for determining the thermal behaviour of cattle manure at unknown heating rates and overcomes the challenges related to the effects of network parameters on the model. [ABSTRACT FROM AUTHOR]

Diesel engines are widely used because of their high power, and diesel particulate filters can effectively control the emission of particulate matter from diesel engines, in which catalysts have a non-negligible role. This paper reviews the research progress of catalyst solutions for catalytic carbon soot combustion in diesel particulate filters in recent years. Firstly, the paper describes the various factors affecting the catalyst activity and the methods for evaluating the catalytic activity. Secondly, it summarizes the catalytic and non-catalytic mechanisms of soot combustion. After that, the paper even focuses on different catalyst types and structures, emphasizing the formulation of catalysts with unique structures. Finally, a brief review of composite regeneration technologies for particulate filters is presented. This paper highlights previous catalyst formulations with good catalytic performance and identifies areas of subsequent research that may provide helpful guidance for future research and commercialization. [ABSTRACT FROM AUTHOR]

Density functional theory calculations have been conducted to investigate the palladium‐catalyzed allylic C−H amination of 1,4‐dienes with commonly available amines. The computations indicate that the reaction begins with the allylic C−H bond cleavage through the concerted proton and two‐electron transfer process to forge the η3‐allyl Pd(II) species. The ensuing C−N bond formation was found to be highly dependent on the basicity of the nucleophile, enabling the regioselectivity switch upon change of the nucleophile. With the weakly basic aromatic amine, the reaction occurs through the hydrogen‐bonding enabled inner‐sphere nucleophilic attack pathway. The distance between the reacting carbon atom and the terminal carbon atom is responsible for the Z/E‐selectivity. The regioselectivity is primarily due to steric repulsion between the allyl group and the ligand. On the other hand, the outer‐sphere nucleophilic attack pathway is favored for the reaction with the more basic aliphatic cyclic amine. The change of the coordinating mode of the allylic moiety was found to play a crucial role in determining the regioselectivity. [ABSTRACT FROM AUTHOR]