Molecular Catalysis最新文献_第10页

A New C2-symmetric {SBI}-type zirconocene complex incorporating electron-donating substituents for highly productive, highly isoselective homo- and copolymerization of propylene 一种新的含给电子取代基的c2对称{SBI}型锆新世配合物，用于丙烯的高效、高等选择的同聚和共聚

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-22 DOI: 10.1016/j.mcat.2025.115599

Dimitra Theodosopoulou , Lorenzo Piola , Alvaro Fernandez , Alexandre Welle , Thierry Roisnel , Jean-François Carpentier , Evgueni Kirillov

The new Me₂Si-bridged bis(indenyl) proligand {Me₂Si(2-Me-4-(3’,5’-tBu₂-4’-OMe-C₆H₂)-5-OMe-6-tBu-Ind)₂}H₂ (1), incorporating bulky and electron-donating substituents both on the indene platform and the 4-aryl-indenyl moiety, was prepared. The corresponding C₂-symmetric ansa-zirconocene complex rac-{Me₂Si(2-Me-4-(3’,5’-tBu₂-4’-OMe-C₆H₂)-5-OMe-6-tBu-Ind)₂}ZrCl₂ (1-ZrCl₂) was synthesized and isolated in pure racemic form, and characterized by NMR spectroscopy, mass spectrometry and X-ray crystallography. The zirconocene complex, once activated with MAO in toluene solution, exhibited propylene polymerization activities at 60 °C up to 217,000 kg(PP).mol(Zr)⁻¹.h⁻¹, affording highly isotactic polypropylene (iPP) with [m]⁴ up to >99 mol % and T_m up to 160.1 °C. Also, the SiO₂-MAO-supported metallocene complex (supp-1-ZrCl₂) was evaluated in slurry bulk propylene polymerization at 70 °C, producing iPP with [m]⁴ content of 99.4−99.5 mol % and low amounts of regiodefects (0.4−0.5 mol %) (T_m up to 159.4 °C), with productivities up to 980,000 kg(PP)·mol(Zr)⁻¹·h⁻¹. Also, polymerization of propylene in the presence of ethylene under slurry conditions allowed obtaining isotactic-rich iPP-co-E copolymers with very high activities up to 3,420,000 kg(PP)·mol(Zr)⁻¹·h⁻¹. The new materials contained ca. 1 wt % of the incorporated ethylene units and featured melting transitions up to 147.5 °C.

制备了新的Me2Si桥接的双（独立基）前配体{Me2Si(2- me -4-(3 ',5 ' - tbu2 -4 ' - ome - c6h2)-5- ome -6- tbu -ind)2}H2(1)，在独立平台和4-芳基独立基部分均含有大体积的供电子取代基。以纯外消旋形式合成了相应的c2对称反锆新统配合物rac-{Me2Si(2- me -4-(3′，5′- tbu2 -4′- ome - c6h2)-5- ome -6- tbu - ind)2}ZrCl2 (1-ZrCl2)，并用NMR谱、质谱和x射线晶体学对其进行了表征。锆新统配合物在甲苯溶液中被MAO活化后，在60℃下具有217000 kg(PP).mol(Zr)−1.h−1的丙烯聚合活性，生成[m]4高达99 mol %、Tm高达160.1℃的高度等规聚丙烯（iPP）。此外，在70°C的料浆体丙烯聚合中，sio2 - mao负载的茂金属配合物（sup1 - zrcl2）得到了[m]4含量为99.4 ~ 99.5 mol %的iPP和少量的区域缺陷（0.4 ~ 0.5 mol %）（Tm可达159.4°C），产量可达98万kg（PP）·mol(Zr)−1·h−1。此外，在浆料条件下，丙烯在乙烯的存在下聚合，可以获得具有等规性丰富的iPP-co-E共聚物，其活性高达3,420,000 kg（PP）·mol(Zr)−1·h−1。新材料含有约1 wt %的合成乙烯单元，并具有高达147.5°C的熔融转变。

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引用次数: 0

Metal-free COF–ionic polymer hybrids for efficient CO2 capture and conversion 用于高效CO2捕获和转化的无金属cof离子聚合物杂化体

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-21 DOI: 10.1016/j.mcat.2025.115612

Meilin Yin , Jingchen Li , Simai Peng , Daying Chen

The industrial implementation of CO₂ cycloaddition remains hindered by catalysts that require multi-step syntheses, co-catalysts or solvents, and yet offer limited recyclability and scalability. Here, we present a metal-free heterogeneous composite catalyst (PImBr@COF) prepared by a 6 h one-pot ship-in-bottle polymerization of imidazolium ionic liquids within the ordered nanochannels of an imine-linked triazine COF (HO-TAPT-COF). This strategy simultaneously embeds Br^– nucleophiles, hydrogen-bond donors (-OH) and CO₂-philic moieties (imine, triazine groups and imidazolium cations) into a crystalline porous scaffold, creating a cooperative activation environment for epoxide ring-opening and CO₂ coupling. The resulting catalyst achieves a CO₂/N₂ selectivity boost from 14.2 to 24.7, maintains a CO₂ uptake of 50.6 mg g⁻¹, and delivers a 99.0 % yield of cyclochloroallyl carbonate under solvent- and cocatalyst-free conditions. Remarkably, both CO₂ capture and catalytic activity show negligible decay after ten cycles. Density functional theory calculations reveal that the confined ionic environment significantly lowers the energy barrier for epoxide activation. This work establishes a rapid, scalable and broadly applicable route for constructing multifunctional COF-based catalysts for sustainable CO₂ utilization.

二氧化碳环加成的工业实施仍然受到需要多步骤合成的催化剂、助催化剂或溶剂的阻碍，而且可回收性和可扩展性有限。在这里，我们提出了一种无金属的非均相复合催化剂（PImBr@COF），该催化剂是由咪唑离子液体在亚胺连接三嗪COF （ho - tap -COF）的有序纳米通道内通过6小时的一锅船瓶聚合制备的。该策略同时将亲核试剂Br、氢键供体（- oh）和亲二氧化碳基团（亚胺、三嗪基团和咪唑阳离子）嵌入到晶体多孔支架中，为环氧化物开环和CO2偶联创造了协同活化环境。该催化剂的CO2/N2选择性从14.2提高到24.7，CO2吸收量保持在50.6 mg g - 1，在无溶剂和无助催化剂的条件下，碳酸环氯丙烯酯的收率为99.0%。值得注意的是，在10个循环后，CO2捕获和催化活性的衰减都可以忽略不计。密度泛函理论计算表明，受限离子环境显著降低了环氧化物活化的能垒。本研究为构建可持续利用CO2的多功能cof催化剂开辟了一条快速、可扩展、广泛适用的途径。

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引用次数: 0

Catalytic performance of Fe modified Co-Mo/γ-Al2O3 catalysts for selective hydrogenation of polycyclic aromatic hydrocarbons Fe改性Co-Mo/γ-Al2O3催化剂对多环芳烃选择性加氢的催化性能

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-21 DOI: 10.1016/j.mcat.2025.115614

Shixuan Guo, Yitong Yan, Tianyu Bai, Han Yang, Meng Huang, Fan Shao, Zhen Xu, Rongrong Li, Wenbin Huang, Qiang Wei

To improve the selectivity in the hydrocracking of polycyclic aromatic hydrocarbons (PAHs), this study innovatively introduced Fe as a modified metal, aiming to weaken the interaction between the Co-Mo active metal and the γ-Al₂O₃ support. A series of Fe-modified Co-Mo/γ-Al₂O₃ catalysts with different Fe content were prepared by impregnation method. Techniques such as XRD, N₂ physical adsorption-desorption, NH₃-TPD, Py-IR, H₂-TPR, HRTEM and XPS were used for characterization, and the catalytic performance of the catalysts were analyzed on a fixed-bed reactor. The pre-impregnation of Fe did not significantly alter the catalyst's crystal structure or pore architecture. However, it reduced the support surface acidity and weakened the metal-support interaction. This weakening facilitated an increase in the population of highly active octahedrally coordinated Mo species and promoted the transformation of active phase slabs with smaller size and higher stacking numbers. The structure of this active phase enhances the dispersion and sulfidation degree of the active metal components, increasing the hydrogenation activity and selectivity of the catalyst. The catalyst modified with 1.0 wt% Fe via pre-impregnation achieved a high phenanthrene (PHE) conversion under the conditions of 330℃, 4 MPa, 600 hydrogen-oil ratio, and 10 h⁻¹ LHSV. The conversion rate of PHE is 81.75 %, the 9,10-dihydrophenanthrene (DHP) selectivity is 23.15 %, and the yield is 18.93 %. Pre-impregnated Fe modified catalysts can more effectively weaken the interaction between the support and the active metal, and are more conducive to the formation of more highly active hexa-coordinated Mo species.

为了提高多环芳烃（PAHs）加氢裂化的选择性，本研究创新性地引入Fe作为改性金属，旨在减弱Co-Mo活性金属与γ-Al2O3载体之间的相互作用。采用浸渍法制备了一系列不同铁含量的Fe改性Co-Mo/γ-Al2O3催化剂。采用XRD、N2物理吸附-脱附、NH3-TPD、Py-IR、H2-TPR、HRTEM和XPS等技术对催化剂进行了表征，并在固定床反应器上对催化剂的催化性能进行了分析。铁的预浸渍没有显著改变催化剂的晶体结构和孔隙结构。然而，它降低了载体表面的酸度，削弱了金属-载体的相互作用。这种弱化有利于高活性八面协调Mo种群的增加，促进了小尺寸、高堆数的活性相板的转变。这种活性相的结构增强了活性金属组分的分散和硫化程度，提高了催化剂的加氢活性和选择性。在330℃、4 MPa、600氢油比、10 h−1 LHSV条件下，用1.0 wt% Fe预浸渍改性的催化剂获得了较高的菲转化率。PHE的转化率为81.75%，对9,10-二氢菲（DHP）的选择性为23.15%，收率为18.93%。预浸渍Fe改性催化剂能更有效地减弱载体与活性金属之间的相互作用，更有利于形成更高活性的六配位Mo物质。

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引用次数: 0

Visible-light-mediated synthesis of 3,3-disubstituted oxindoles catalyzed by graphitic phase carbon nitride 石墨相氮化碳在可见光催化下合成3,3-二取代氧吲哚

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-21 DOI: 10.1016/j.mcat.2025.115602

Keshen Qin , Zhenkai Lei , Ziren Chen , Bin Wang , Yonghong Zhang , Yu Xia , Shaofeng Wu , Weiwei Jin , Chenjiang Liu

An efficient method has been established for preparing trihalomethylated oxindoles from N-aryl acrylamides employing graphitic phase carbon nitride (g-C₃N₄) as catalyst under purple light irradiation. For the first time, the heterogeneous photocatalyst was employed to synthesize substituted oxindoles. The pivotal stage of this reaction comprises the g-C₃N₄-photocatalyzed activation of N-aryl acrylamides toward cationic radical intermediates, while tetrahalomethane decomposes to generate trihalomethyl radicals. Employing this strategy provides broad functional group compatibility, enables catalyst recycling, and utilizes mild conditions. Large-scale synthesis coupled to derivatization investigations confirmed the substantial prospects of the approach.

在紫外光照射下，以石墨相氮化碳（g-C3N4）为催化剂，建立了n -芳基丙烯酰胺制备三卤甲基化氧吲哚的有效方法。首次采用非均相光催化剂合成了取代吲哚。该反应的关键阶段包括g- c3n4光催化n -芳基丙烯酰胺向阳离子自由基中间体的活化，而四卤甲烷分解生成三卤甲基自由基。采用这种策略提供了广泛的官能团兼容性，使催化剂回收，并利用温和的条件。大规模合成加上衍生化研究证实了该方法的巨大前景。

引用次数: 0

Insights on the mechanism of the reaction between nitric oxide and aziridines with and without CaO catalyst 有/无CaO催化剂下一氧化氮与氮嘧啶反应机理的研究

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-20 DOI: 10.1016/j.mcat.2025.115609

Hanan Enadi , Shanmugasundaram Kamalakannan , Mohamed Oussama Zouaghi , Youssef Arfaoui , Muneerah Mogren Al-Mogren , Majdi Hochlaf

The reactions between nitric oxide (NO) and an aziridine in gas phase and using calcium oxide (CaO) surfaces are investigated using Density Functional Theory (DFT) to explore the formation of valuable nitrogen-containing heterocycles. Gas-phase analyses identify CH-side ring opening of aziridine as the most favorable pathway for radical attack by NO, leading to stable intermediates and products such as oxadiazolidines and diazetidines. Solvent effects are found to further enhance the reactivity, with water notably reducing activation barriers. Also, we show that electron-withdrawing groups significantly lower activation energies and improve reaction spontaneity. Besides, the CH cleavage mechanism is confirmed to be energetically preferred while the reaction occurs at the CaO(100) surface or CaO cluster, facilitated by surface basicity and favorable transition state stabilizations. Natural Bond Orbital (NBO) analysis shows the radical character development and charge redistribution during key steps. Further, periodic computations reveal that the oxadiazolidine production over the CaO(100) slab is kinetically favored compared to the diazetidine synthesis, whereas in gas phase this is due to thermodynamical considerations. These results provide insights into the reactivity of NO on oxide surfaces and should help guiding the design of efficient NO capture and transformation strategies for synthetic and environmental applications.

利用密度泛函理论（DFT）研究了一氧化氮（NO）与氮吡啶在气相和氧化钙（CaO）表面的反应，探讨了有价氮杂环的形成。气相分析表明，氮化吡啶的ch侧开环是NO自由基攻击的最有利途径，导致稳定的中间体和产物，如恶二唑烷和重氮杂啶。发现溶剂效应进一步提高了反应性，水显著降低了活化障碍。此外，我们还发现吸电子基团显著降低了活化能，提高了反应的自发性。此外，由于表面碱性和良好的过渡态稳定，当反应发生在CaO（100）表面或CaO簇上时，CH的解理机制在能量上更有利。自然键轨道（NBO）分析表明，在关键步骤中自由基的发展和电荷的重新分配。此外，周期性计算表明，与重氮啶合成相比，CaO（100）板上的恶二唑烷生产在动力学上更有利，而在气相中，这是由于热力学方面的考虑。这些结果为NO在氧化物表面的反应性提供了见解，并有助于指导合成和环境应用中有效的NO捕获和转化策略的设计。

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引用次数: 0

Synergistic promotion of methane oxidation over Ni/CeO₂-ZrO₂ catalysts: The role of the Ni-support interface and oxygen vacancies Ni/ ceo2 -ZrO 2催化剂对甲烷氧化的协同促进：Ni-载体界面和氧空位的作用

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-20 DOI: 10.1016/j.mcat.2025.115601

Weijie Xu , Chunlan Qin , Lili Zhang , Lidong Zhang , Chenliang He

Low-temperature catalytic oxidation is a crucial technology for the abatement of methane, a potent greenhouse gas. In this work, a series of Ni and Zr co-doped CeO₂ catalysts were synthesized via a hydrothermal method to investigate the synergistic effects between the active metal and the modified support. Characterization revealed that while Ni nanoparticles served as the primary active sites, the incorporation of 5 wt% Zr into the CeO₂ lattice to form a Ce-Zr solid solution was critical. This modification enhanced the concentration of surface oxygen vacancies, improved the dispersion of Ni nanoparticles, and strengthened the metal-support interaction. Consequently, the optimized 20%Ni-5%Zr/CeO₂ catalyst exhibited superior performance, achieving 90% methane conversion (T₉₀) at 418°C, significantly lower than that of Ni/CeO₂ (443°C) and pure CeO₂ (503°C). Density functional theory (DFT) calculations further confirmed the synergistic effect, revealing that the Ni-Zr interfacial sites significantly lower the activation energy barrier for the initial C-H bond cleavage. Notably, the catalyst demonstrated exceptional stability over 50 h at 425°C and robust water tolerance. This work highlights a synergistic strategy for designing highly active and durable ceria-based catalysts for environmental applications.

低温催化氧化是减少甲烷（一种强效温室气体）的关键技术。本文通过水热法合成了一系列Ni和Zr共掺杂的CeO2催化剂，研究了活性金属与改性载体之间的协同作用。表征表明，虽然Ni纳米粒子是主要的活性位点，但在CeO2晶格中掺入5wt %的Zr以形成Ce-Zr固溶体是至关重要的。该修饰提高了表面氧空位的浓度，改善了Ni纳米颗粒的分散性，增强了金属-载体的相互作用。结果表明，优化后的20%Ni-5%Zr/CeO2催化剂表现出优异的性能，在418℃下甲烷转化率达到90% (T90)，显著低于Ni/CeO2（443℃）和纯CeO2（503℃）。密度泛函理论（DFT）计算进一步证实了协同效应，表明Ni-Zr界面位点显著降低了初始C-H键裂解的活化能垒。值得注意的是，该催化剂在425°C下表现出50小时的优异稳定性和良好的耐水性。这项工作强调了为环境应用设计高活性和耐用的二氧化铈基催化剂的协同策略。

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引用次数: 0

Simultaneous improvement of thermostability and activity in a novel Streptomyces trypsin via rational design and structure-function characterization 一种新型链霉菌胰蛋白酶通过合理设计和结构功能表征同时改善其热稳定性和活性

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-20 DOI: 10.1016/j.mcat.2025.115611

Jia Chen , Guangyang Jiang , Yongqiang Tian

Trypsin is extensively utilized in industrial applications such as protein hydrolysis, food processing, and leather softening. However, its broader applicability is often hindered by insufficient thermostability, particularly in microbial-derived enzymes. In this study, a novel trypsin from Streptomyces populi was selected as a candidate for thermostability enhancement. Two multi-site variants, Design1 and Design2, were constructed through a rational design strategy and comprehensively characterized via high-temperature molecular dynamics simulations and enzymatic assays. Computational analyses revealed that both variants exhibited substantially reduced backbone root mean square deviation (RMSD) and residue-level root mean square fluctuation (RMSF) under thermal conditions, indicating improved structural stability. The T₅₀ of Design1 and Design2 increased from 53.1 °C (wild-type trypsin) to 58.5 °C and 59.3 °C, respectively. Their half-life at 50 °C was significantly prolonged from 158 min to 630 and 693 min. In addition, enzymatic activities reached 70.4 U/mL and 75.5 U/mL, representing 99.4 % and 113.9 % increases relative to the wild-type trypsin. The catalytic efficiencies (kcat/Km) also improved markedly, reaching 1.2 × 10⁶ and 1.4 × 10⁶ min^-1 mM^-1, respectively, compared to 3.2 × 10⁵ min^-1 mM^-1 for the wild-type trypsin. These findings demonstrate that rational multi-site mutagenesis is an effective approach to simultaneously enhance the thermostability and catalytic efficiency of trypsin. This work provides a robust framework for the development of thermotolerant trypsin variants and contributes to the rational design of high-performance enzymes for industrial applications.

胰蛋白酶广泛应用于工业领域，如蛋白质水解、食品加工和皮革软化。然而，其更广泛的适用性往往受到热稳定性不足的阻碍，特别是在微生物衍生的酶中。在这项研究中，从平民链霉菌中选择了一种新的胰蛋白酶作为热稳定性增强的候选物质。通过合理的设计策略构建了两个多位点变异Design1和Design2，并通过高温分子动力学模拟和酶促实验对其进行了全面表征。计算分析表明，在热条件下，这两种变体的主干均方根偏差（RMSD）和残余水平均方根波动（RMSF）都显著降低，表明结构稳定性得到了改善。Design1和Design2的T50分别从53.1°C（野生型胰蛋白酶）增加到58.5°C和59.3°C。它们在50℃下的半衰期从158 min显著延长到630 min和693 min。酶活性分别达到70.4 U/mL和75.5 U/mL，分别比野生型胰蛋白酶提高99.4%和113.9%。催化效率（kcat/Km）也显著提高，分别达到1.2 × 10⁶和1.4 × 10⁶min-1 mM-1，而野生型胰蛋白酶的催化效率为3.2 × 10⁶min-1 mM-1。这些结果表明，合理的多位点诱变是同时提高胰蛋白酶热稳定性和催化效率的有效途径。这项工作为开发耐热胰蛋白酶变体提供了一个强大的框架，并有助于合理设计用于工业应用的高性能酶。

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引用次数: 0

Ball-milling-induced lattice distortion in Cu2O catalysts for the direct synthesis of tetramethoxysilane from methanol and silicon 由甲醇和硅直接合成四甲基氧基硅烷的Cu2O催化剂中球磨引起的晶格畸变

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-20 DOI: 10.1016/j.mcat.2025.115610

Yulong Liu , Yongxia Zhu , Jiajian Gao , Lili Zhang , Shihong Pei , Guangwen Xu , Ziyi Zhong , Fabing Su

This work investigates the catalytic mechanism and structure–activity relationship of Cu₂O catalysts in the direct synthesis of tetramethoxysilane (TMOS) from methanol and silicon. To overcome the drawbacks of conventional multi-step TMOS synthesis—such as severe corrosion and low atom economy—we propose a one-step direct route. Two model catalysts were employed: untreated Cu₂O and ball-milled Cu₂O (Cu₂O-M). After 20 h of reaction at 240 °C, Cu₂O-M achieved markedly higher silicon conversion and TMOS selectivity. Characterization shows that ball milling induces lattice distortion, evidenced by a negative shift in the EPR g-factor and a positive O 1 s XPS shift, indicating electron transfer from O to Cu and the formation of strained lattice oxygen species. Mechanistic studies reveal that methanol chemisorption leads to the reduction of Cu₂O to metallic Cu⁰, which then migrates to the silicon surface, cleaves Si-Si bonds, and promotes the generation of TMOS. The process of ball milling accelerates this Cu₂O → Cu⁰ transformation, which enhances methanol dissociation and promotes the selective formation of Si–OCH₃ bonds while suppressing SiO₂ byproducts. These findings provide new mechanistic insights that can guide the rational design of copper-based catalysts for direct silane synthesis.

研究了Cu2O催化剂在甲醇和硅直接合成四甲基氧基硅烷（TMOS）中的催化机理和构效关系。为了克服传统多步骤合成TMOS的缺点，如严重的腐蚀和低原子经济性，我们提出了一步直接路线。采用两种模型催化剂：未经处理的Cu2O和球磨的Cu2O （Cu2O- m）。在240℃下反应20 h后，Cu2O-M的硅转化率和TMOS选择性显著提高。表征表明，球磨引起晶格畸变，表现为EPR g因子的负位移和O 1 s XPS的正位移，表明电子从O向Cu转移，形成了应变晶格氧。机理研究表明，甲醇化学吸附导致Cu2O还原为金属Cu0， Cu0迁移到硅表面，劈裂Si-Si键，促进TMOS的生成。球磨过程加速了这种Cu2O→Cu0的转变，促进了甲醇的解离，促进了Si-OCH3键的选择性形成，同时抑制了SiO2的副产物。这些发现为指导铜基硅烷直接合成催化剂的合理设计提供了新的机理见解。

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引用次数: 0

Single-point mutagenesis expands the catalytic capability of ene-reductase for one-pot synthesis of cyanoesters 单点诱变扩大了酶还原酶催化氰酸酯一锅合成的能力

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-20 DOI: 10.1016/j.mcat.2025.115605

Xin-Yue Fan , Xue Yang , Hao-Xuan Luo , Ru-De Lin , Wan-Xia Wu , Kun Li , Hai-Chun Liu , Na Wang

Ene-reductases (ERs) have emerged as powerful biocatalysts for asymmetric hydrogenation, offering a sustainable alternative to traditional chemical catalysts. Recent progress in protein engineering and molecular biology has enabled substantial improvements in the stereoselectivity, stability, and catalytic efficiency of enzymes, thereby fulfilling industrial requirements. These advancements have been achieved through various strategies, including scaffold sampling and cyclic permutation. In this work, structural analysis has guided our efforts to target the hotspot residue W66 in NADH-dependent cyclohexenone ene reductase (NCR, from Zymomonas mobilis) for site-saturation mutagenesis. Consequently, two mutants, NCR-W66E and NCR-W66T, were obtained, both of which exhibited significantly enhanced catalytic activity. We have then developed a metal-free, aqueous, one-pot Knoevenagel-hydrogenation (K-H) tandem system that operates under ambient conditions (temperature and pressure), integrating the spontaneous Knoevenagel condensation with enzymatic hydrogenation catalyzed by optimized NCR mutants. It efficiently synthesizes a series of arylcyanoesters, which are key intermediates for the production of pharmaceuticals, pesticides, and fine chemicals, with yields reaching up to 95 %. Moreover, the scalability of this platform has been successfully demonstrated through a 50-fold increase in scale. Enzyme kinetics and computational simulations elucidated that the NCR-W66T variant features a larger substrate entrance and a more favorable substrate-reaction conformation. This study presents a sustainable biosynthetic route for the production of arylcyanoesters and further deepens the molecular understanding of the structure-function relationships in enzymes.

烯还原酶（er）已成为不对称氢化反应的强大生物催化剂，是传统化学催化剂的可持续替代品。蛋白质工程和分子生物学的最新进展使酶的立体选择性、稳定性和催化效率得到了实质性的改善，从而满足了工业需求。这些进步是通过各种策略实现的，包括支架采样和循环排列。在这项工作中，结构分析指导了我们针对nadh依赖性环己烯还原酶（NCR）的热点残基W66进行位点饱和诱变。因此，获得了两个突变体NCR-W66E和NCR-W66T，这两个突变体都表现出显著增强的催化活性。然后，我们开发了一种无金属、水、一锅Knoevenagel-氢化（K-H）串联系统，该系统在环境条件下（温度和压力）运行，将自发的Knoevenagel缩合与优化的NCR突变体催化的酶促氢化结合起来。它高效地合成了一系列芳基氰酸酯，这是生产药品、农药和精细化学品的关键中间体，收率可达95%以上。此外，该平台的可扩展性已经成功地通过规模增加50倍来证明。酶动力学和计算模拟表明，NCR-W66T变体具有更大的底物入口和更有利的底物反应构象。本研究为芳基氰酸酯的生产提供了一条可持续的生物合成途径，进一步加深了对酶的结构-功能关系的分子认识。

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引用次数: 0

Experimental and kinetic treatments for rates affected by deactivation in alkane dehydrogenation over dispersed metal nanoparticles 分散金属纳米颗粒上烷烃脱氢失活影响速率的实验和动力学处理

IF 4.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis

Pub Date : 2025-11-19 DOI: 10.1016/j.mcat.2025.115606

Zhongyao Zhang , Wenshuo Hu

Catalyst deactivation in alkane dehydrogenation often arises from the accumulation of less-reactive organic species that occupy surface bare-atom ensembles. The formation of these species depends sensitively on reaction conditions and time-on-stream, leading to observed kinetics that are distorted by deactivation events and do not reflect the intrinsic catalytic responses intended by experiments. Here, we discuss an experimental and kinetic approach to treat rate data affected by deactivation that proceeds in two regimes: 1) a fast phase, occurring over the first few turnovers and reflecting the formation of less-reactive species on clean surfaces, and 2) a slow phase, resulting from the continued buildup of these species on surfaces already crowded during the fast phase. The fast phase exhibits short timescales and is often poorly defined or essentially undetectable; for a given catalyst, it depends only on the initial reaction condition to which fresh samples are exposed. This insight enables an experimental strategy where fresh catalysts are preconditioned under a controlled initial reaction environment, setting a reference coverage by deactivating a specified fraction of active sites and thereby preserving the fast-phase influence at a fixed extent. This fast-phase deactivation is accounted for by adding a constant fractional-coverage term to the site-balance equation, with all other terms dependent only on the slow deactivation phase, for which well-resolved data and empirical correction methods are available. This strategy is illustrated here with methylcyclohexane dehydrogenation to toluene on dispersed Pt and Pd nanoparticles, but its conceptual and practical implications extend beyond the specific systems examined.

烷烃脱氢过程中催化剂失活通常是由于占据表面裸原子系综的活性较低的有机物质的积累引起的。这些物质的形成敏感地依赖于反应条件和流上时间，导致观察到的动力学被失活事件扭曲，不能反映实验预期的内在催化反应。在这里，我们讨论了一种实验和动力学方法来处理受失活影响的速率数据，失活在两种情况下进行：1)快速阶段，发生在最初的几次循环中，反映了清洁表面上反应性较低的物质的形成；2)缓慢阶段，由于这些物质在快速阶段已经拥挤的表面上继续积聚。快相具有短的时间尺度，通常定义不清或基本上无法检测；对于给定的催化剂，它只取决于新鲜样品所处的初始反应条件。这一见解支持了一种实验策略，即在受控的初始反应环境下对新鲜催化剂进行预处理，通过使特定部分的活性位点失活来设定参考覆盖范围，从而将快相影响保持在固定程度。通过在位置平衡方程中添加一个恒定的分数覆盖项来解释这种快速失活，而所有其他项仅依赖于缓慢失活阶段，对于缓慢失活阶段，可以获得良好的数据和经验校正方法。这种策略在这里用甲基环己烷脱氢到分散的Pt和Pd纳米颗粒上的甲苯来说明，但其概念和实际意义超出了所研究的特定系统。

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