Pub Date : 2026-02-05DOI: 10.1021/acscatal.5c08606
Shufen Ma, Yachao Wang, Guofeng Zhao, Weixin Huang, Cong Fu
Photocatalytic oxidative dehydrogenation of ethane (ODHE) is a promising route to ethylene under mild conditions, yet achieving a high yield and selectivity is challenging due to the inert C–H bonds and overoxidation to CO2. In this study, we present ZnO fine nanoparticles decorated with highly dispersed Pd species and featuring closely associated interfacial oxygen vacancies (Ov) for highly selective ODHE. The optimized catalyst achieves a C2H4 production rate of 8.5 mmol g–1 h–1 with a selectivity of up to 96.1%, surpassing most reported photo- and thermocatalysts and maintaining robust stability for over 10 h. Through a combination of operando DRIFTS, in situ XPS, and in situ EPR analyses, we demonstrate that the enhanced photocatalytic performance stems from a synergistic, spatially separated dual-site configuration involving Pd species and adjacent interfacial Ov. This configuration enhances spatial charge separation, promotes oxygen activation, and facilitates the selective conversion of C2H6 into key *C2H4 intermediates, thereby boosting ethylene formation. This work not only provides fundamental insights into the photocatalytic ODHE mechanism but also underscores the importance of interfacial engineering in the design of highly efficient photocatalysts for alkane conversion.
乙烷的光催化氧化脱氢（ODHE）是在温和条件下制备乙烯的一种很有前途的途径，但由于惰性的C-H键和过度氧化成二氧化碳，实现高收率和选择性是具有挑战性的。在这项研究中，我们提出了用高度分散的钯修饰的ZnO纳米粒子，并具有密切相关的界面氧空位（Ov），用于高选择性的ODHE。优化后的催化剂的C2H4产率为8.5 mmol g-1 h - 1，选择性高达96.1%，超过了大多数报道的光催化剂和热催化剂，并保持了超过10小时的稳定。通过operando DRIFTS、原位XPS和原位EPR分析的组合，我们证明了增强的光催化性能源于协同的、空间分离的双位点配置，涉及Pd物种和相邻的界面Ov。这种构型增强了空间电荷分离，促进氧活化，有利于C2H6选择性转化为关键的*C2H4中间体，从而促进乙烯的生成。这项工作不仅为光催化ODHE机理提供了基本的见解，而且强调了界面工程在设计高效烷烃转化光催化剂中的重要性。
{"title":"Synergistic Bifunctionality of Interfacial Pd–Ov Sites on ZnO for Highly Selective Photocatalytic Ethane Dehydrogenation","authors":"Shufen Ma, Yachao Wang, Guofeng Zhao, Weixin Huang, Cong Fu","doi":"10.1021/acscatal.5c08606","DOIUrl":"https://doi.org/10.1021/acscatal.5c08606","url":null,"abstract":"Photocatalytic oxidative dehydrogenation of ethane (ODHE) is a promising route to ethylene under mild conditions, yet achieving a high yield and selectivity is challenging due to the inert C–H bonds and overoxidation to CO<sub>2</sub>. In this study, we present ZnO fine nanoparticles decorated with highly dispersed Pd species and featuring closely associated interfacial oxygen vacancies (Ov) for highly selective ODHE. The optimized catalyst achieves a C<sub>2</sub>H<sub>4</sub> production rate of 8.5 mmol g<sup>–1</sup> h<sup>–1</sup> with a selectivity of up to 96.1%, surpassing most reported photo- and thermocatalysts and maintaining robust stability for over 10 h. Through a combination of <i>operando</i> DRIFTS, <i>in situ</i> XPS, and <i>in situ</i> EPR analyses, we demonstrate that the enhanced photocatalytic performance stems from a synergistic, spatially separated dual-site configuration involving Pd species and adjacent interfacial Ov. This configuration enhances spatial charge separation, promotes oxygen activation, and facilitates the selective conversion of C<sub>2</sub>H<sub>6</sub> into key *C<sub>2</sub>H<sub>4</sub> intermediates, thereby boosting ethylene formation. This work not only provides fundamental insights into the photocatalytic ODHE mechanism but also underscores the importance of interfacial engineering in the design of highly efficient photocatalysts for alkane conversion.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"1 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1021/acscatal.5c07197
Danial Farooq, Lucy Costley-Wood, Sebastian Stockenhuber, Antonis Vamvakeros, Stephen W. T. Price, Lisa J. Allen, Jakub Drnec, James Paterson, Mark Peacock, Daniel J. M. Irving, Philip A. Chater, Andrew M. Beale
The transition to net-zero emissions hinges on circular economy strategies that valorize waste and enhance resource efficiency. Among X-to-liquid (XTL) technologies, the Fischer-Tropsch (FT) process stands out for converting biomass, waste, and CO2 into hydrocarbons and chemicals, especially when powered by renewable hydrogen. Cobalt-based catalysts are preferred in FT synthesis due to their efficiency and CO2 tolerance, yet their catalytic performance is closely tied to their polymorphic structures─face-centered cubic (FCC), hexagonal close-packed (HCP), and stacking-faulted intergrowths thereof. HCP cobalt has been shown to exhibit high activity and selectivity for higher hydrocarbons and oxygenates, particularly when transformed into cobalt carbide (Co2C), which forms more readily at low H2/CO ratios. This study presents a quantitative analysis of cobalt polymorphs and stacking faults in Mn-promoted Co/TiO2 FT catalysts from in situ powder X-ray diffraction (XRD) data and X-ray Diffraction Computed Tomography (XRD-CT) data from spent catalysts in order to obtain a more complete correlation of structural features with catalytic performance. By modeling stacking fault probabilities using supercell simulations, the proportion of faulted FCC and HCP domains was determined across varying Mn loadings (0–5%). Increased Mn loading was found to decrease stacking faults in the FCC phase while increasing them in HCP, promoting the formation of HCP domains and ultimately Co2C under reaction conditions. Notably, the 3% Mn-loaded sample showed a marked rise in HCP content and Co2C formation, correlating with the highest observed alcohol and olefin selectivity. These findings highlight a critical structure–function relationship: Mn facilitates a transformation from FCC to HCP and then to Co2C, this final transition driven by similar stacking sequences and metal–support interactions. The findings show that Mn promotion not only stabilizes smaller Co particles and enhances its dispersion, but also modulates the distribution of Co polymorphs and stacking faults, leading to altered catalytic behavior. This highlights the importance of stacking fault characterization for optimizing FT catalyst design and performance, and suggests pathways to more efficient and selective carbon-neutral fuel production through engineered polymorphic and interfacial structures.
{"title":"Mn-Promoted Co/TiO2 Catalysts: Quantitative Analysis of Cobalt Polymorphs and Stacking Faults and Its Effect on Fischer-Tropsch Synthesis Performance","authors":"Danial Farooq, Lucy Costley-Wood, Sebastian Stockenhuber, Antonis Vamvakeros, Stephen W. T. Price, Lisa J. Allen, Jakub Drnec, James Paterson, Mark Peacock, Daniel J. M. Irving, Philip A. Chater, Andrew M. Beale","doi":"10.1021/acscatal.5c07197","DOIUrl":"https://doi.org/10.1021/acscatal.5c07197","url":null,"abstract":"The transition to net-zero emissions hinges on circular economy strategies that valorize waste and enhance resource efficiency. Among X-to-liquid (XTL) technologies, the Fischer-Tropsch (FT) process stands out for converting biomass, waste, and CO<sub>2</sub> into hydrocarbons and chemicals, especially when powered by renewable hydrogen. Cobalt-based catalysts are preferred in FT synthesis due to their efficiency and CO<sub>2</sub> tolerance, yet their catalytic performance is closely tied to their polymorphic structures─face-centered cubic (FCC), hexagonal close-packed (HCP), and stacking-faulted intergrowths thereof. HCP cobalt has been shown to exhibit high activity and selectivity for higher hydrocarbons and oxygenates, particularly when transformed into cobalt carbide (Co<sub>2</sub>C), which forms more readily at low H<sub>2</sub>/CO ratios. This study presents a quantitative analysis of cobalt polymorphs and stacking faults in Mn-promoted Co/TiO<sub>2</sub> FT catalysts from in situ powder X-ray diffraction (XRD) data and X-ray Diffraction Computed Tomography (XRD-CT) data from spent catalysts in order to obtain a more complete correlation of structural features with catalytic performance. By modeling stacking fault probabilities using supercell simulations, the proportion of faulted FCC and HCP domains was determined across varying Mn loadings (0–5%). Increased Mn loading was found to decrease stacking faults in the FCC phase while increasing them in HCP, promoting the formation of HCP domains and ultimately Co<sub>2</sub>C under reaction conditions. Notably, the 3% Mn-loaded sample showed a marked rise in HCP content and Co<sub>2</sub>C formation, correlating with the highest observed alcohol and olefin selectivity. These findings highlight a critical structure–function relationship: Mn facilitates a transformation from FCC to HCP and then to Co<sub>2</sub>C, this final transition driven by similar stacking sequences and metal–support interactions. The findings show that Mn promotion not only stabilizes smaller Co particles and enhances its dispersion, but also modulates the distribution of Co polymorphs and stacking faults, leading to altered catalytic behavior. This highlights the importance of stacking fault characterization for optimizing FT catalyst design and performance, and suggests pathways to more efficient and selective carbon-neutral fuel production through engineered polymorphic and interfacial structures.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"11 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1021/acscatal.5c07788
Yong Tang, Yongqi Zeng, Chunyu Wang, Chuang Du, Fengxi Li, Lei Wang
The stereoselective cross-dehydrogenative coupling (CDC) reaction represents a highly promising approach for the direct synthesis of high-value non-natural amino acids. The photoenzyme cascade strategy synergistically integrates the reactivity of photocatalysts with the selectivity of enzymes, demonstrating attractive potential for eco-friendly asymmetric synthesis. In this study, we report a photoartificial CDCase cascade method for the asymmetric CDC reaction between N-aryl glycine esters and cycloketones. The optimal artificial CDCase was constructed by anchoring the biotinylated Cu-phenanthroline cofactor (5-NH2Phen-biotin*Cu(OAc)2) within the double mutant (S112H–K121M) of streptavidin obtained through genetic engineering optimization. In a mild aqueous medium, the resulting artificial CDCase cooperates with photocatalysis, efficiently catalyzing the asymmetric CDC reaction at a low enzyme loading (0.5 mol %), yielding a series of α-cycloketone-substituted N-aryl glycine esters with good yields and stereoselectivities. Comprehensive molecular docking and molecular dynamics (MD) simulations provided insights into the critical complex intermediates involved in the proposed reaction mechanism and clarified the interactions between the artificial CDCase and its substrates. Furthermore, through analysis of interatomic distances between pivotal reactive carbon centers and probable nucleophilic attack directions, we have deciphered the structural foundation underlying the formation of the predominant conformation, concurrently rationalizing the enhanced reactivity and stereoselectivity observed for the S112H–K121 M mutant.
{"title":"Photoenzymatic Cascade Catalysis with an Artificial CDCase for Stereoselective Cross-Dehydrogenative Coupling","authors":"Yong Tang, Yongqi Zeng, Chunyu Wang, Chuang Du, Fengxi Li, Lei Wang","doi":"10.1021/acscatal.5c07788","DOIUrl":"https://doi.org/10.1021/acscatal.5c07788","url":null,"abstract":"The stereoselective cross-dehydrogenative coupling (CDC) reaction represents a highly promising approach for the direct synthesis of high-value non-natural amino acids. The photoenzyme cascade strategy synergistically integrates the reactivity of photocatalysts with the selectivity of enzymes, demonstrating attractive potential for eco-friendly asymmetric synthesis. In this study, we report a photoartificial CDCase cascade method for the asymmetric CDC reaction between <i>N</i>-aryl glycine esters and cycloketones. The optimal artificial CDCase was constructed by anchoring the biotinylated Cu-phenanthroline cofactor (5-NH<sub>2</sub>Phen-biotin*Cu(OAc)<sub>2</sub>) within the double mutant (S112H–K121M) of streptavidin obtained through genetic engineering optimization. In a mild aqueous medium, the resulting artificial CDCase cooperates with photocatalysis, efficiently catalyzing the asymmetric CDC reaction at a low enzyme loading (0.5 mol %), yielding a series of α-cycloketone-substituted <i>N</i>-aryl glycine esters with good yields and stereoselectivities. Comprehensive molecular docking and molecular dynamics (MD) simulations provided insights into the critical complex intermediates involved in the proposed reaction mechanism and clarified the interactions between the artificial CDCase and its substrates. Furthermore, through analysis of interatomic distances between pivotal reactive carbon centers and probable nucleophilic attack directions, we have deciphered the structural foundation underlying the formation of the predominant conformation, concurrently rationalizing the enhanced reactivity and stereoselectivity observed for the S112H–K121 M mutant.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"1 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1021/acscatal.5c08299
Sergio Fernández, Klaudia Michaliszyn, Ekaterina S. Smirnova, Marc Robert, Josep M. Luis, Julio Lloret-Fillol
We report a Nickel CO2 reduction electrocatalyst based on a C3-symmetric tris(phosphino)alkyl ligand, CNPPh3, which displays a metalated axial carbon atom. Catalyst NiHBr selectively reduces CO2 to CO (FYCO = 94%) at −2.3 V vs Fc+/0 with a TO Fmax = 65 s–1 in DMF/[TBA]PF6 with 3.5 M of added H2O. Cyclic voltammetry (CV) and an exhaustive computational study of the reaction mechanism show that our NiII complex undergoes two one-electron reduction events before the CO2 binding step. Afterward, the catalytic CO2 reduction takes place through a reduction-first pathway. The formation of a Ni–CO intermediate along the CO2 reduction pathway was inferred by CV, and the corresponding [NiII–CO]+ complex was isolated. FTIR spectroelectrochemistry (SEC) allowed for the detection of three different Ni–CO species: [Ni–CO]+, [Ni–CO]0, and [Ni–CO]−. This work provides critical insights into the electrocatalytic CO2 reduction, laying the foundation for efficient CO2 conversion strategies.
我们报道了一种基于c3对称三（磷酸）烷基配体CNPPh3的镍CO2还原电催化剂，它显示了一个金属化的轴向碳原子。催化剂NiHBr在DMF/[TBA]PF6中，添加3.5 M的H2O，在−2.3 V vs Fc+/0条件下选择性地将CO2还原为CO (FYCO = 94%), to - Fmax = 65 s-1。循环伏安法（CV）和详尽的反应机理计算研究表明，我们的NiII配合物在CO2结合之前经历了两次单电子还原事件。之后，通过还原优先途径进行催化CO2还原。通过CV推测了Ni-CO中间体沿CO2还原途径的形成，并分离出相应的[NiII-CO]+配合物。FTIR光谱电化学（SEC）允许检测三种不同的Ni-CO物种：[Ni-CO]+， [Ni-CO]0和[Ni-CO]−。这项工作为电催化二氧化碳还原提供了重要的见解，为有效的二氧化碳转化策略奠定了基础。
{"title":"Selective CO2 Electroreduction to CO by an Organometallic Nickel Catalyst Featuring a C3–Symmetric Tris(Phosphino)Alkyl Ligand","authors":"Sergio Fernández, Klaudia Michaliszyn, Ekaterina S. Smirnova, Marc Robert, Josep M. Luis, Julio Lloret-Fillol","doi":"10.1021/acscatal.5c08299","DOIUrl":"https://doi.org/10.1021/acscatal.5c08299","url":null,"abstract":"We report a Nickel CO<sub>2</sub> reduction electrocatalyst based on a <i>C</i><sub>3</sub>-symmetric tris(phosphino)alkyl ligand, CNPPh<sub>3</sub>, which displays a metalated axial carbon atom. Catalyst <b>Ni</b><sup><b>H</b></sup><sub><b>Br</b></sub> selectively reduces CO<sub>2</sub> to CO (FY<sub>CO</sub> = 94%) at −2.3 V vs Fc<sup>+/0</sup> with a TO <i>F</i><sub>max</sub> = 65 s<sup>–1</sup> in DMF/[TBA]PF<sub>6</sub> with 3.5 M of added H<sub>2</sub>O. Cyclic voltammetry (CV) and an exhaustive computational study of the reaction mechanism show that our Ni<sup>II</sup> complex undergoes two one-electron reduction events before the CO<sub>2</sub> binding step. Afterward, the catalytic CO<sub>2</sub> reduction takes place through a reduction-first pathway. The formation of a Ni–CO intermediate along the CO<sub>2</sub> reduction pathway was inferred by CV, and the corresponding [Ni<sup>II</sup>–CO]<sup>+</sup> complex was isolated. FTIR spectroelectrochemistry (SEC) allowed for the detection of three different Ni–CO species: [Ni–CO]<sup>+</sup>, [Ni–CO]<sup>0</sup>, and [Ni–CO]<sup>−</sup>. This work provides critical insights into the electrocatalytic CO<sub>2</sub> reduction, laying the foundation for efficient CO<sub>2</sub> conversion strategies.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"294 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The hydrodeoxygenation of furfural to 2-methylfuran represents a critical route for biomass valorization, although hindered by slow kinetics and undesired side reactions. Key challenges involve designing catalytic sites that enable enhanced H2 activation and vertically oriented furfural adsorption. Herein, we engineer a self-pillared silicalite-1 nanosheet-supported Cu–Zn bimetallic catalyst to overcome these limitations. The hierarchically porous silicalite-1 architecture serves dual functions: (1) stabilizing highly dispersed Cu–Zn alloy interfaces and (2) inducing electronic modulation that synergistically enhances dissociative H2 chemisorption and spillover. Crucially, this interface imposes a stable η1-(O)-aldehyde adsorption configuration for both furfural and its furfuryl alcohol intermediate, effectively suppressing ring-hydrogenation-inducing flat η2-(C,O) adsorption modes. At a moderate 180 °C, this integrated catalyst design achieves a 2-methylfuran turnover frequency (TOF) of 20.6 h–1 with near-quantitative selectivity (99.2% yield) after one hour of reaction.
{"title":"Construction of Synergistic Cu–Zn Alloy Interfaces within Hierarchical Zeolite Nanosheets for High-Efficiency Production of 2-Methylfuran from Furfural","authors":"Xiaozhou Chen,Xin Yu,Shuaishuai Zhou,Hao Yang,Qian Li,Qiang Deng,Zhenheng Diao,Zongjing Lu,Zongyuan Wang,Jianxing Gan,Yajie Tian","doi":"10.1021/acscatal.5c05480","DOIUrl":"https://doi.org/10.1021/acscatal.5c05480","url":null,"abstract":"The hydrodeoxygenation of furfural to 2-methylfuran represents a critical route for biomass valorization, although hindered by slow kinetics and undesired side reactions. Key challenges involve designing catalytic sites that enable enhanced H2 activation and vertically oriented furfural adsorption. Herein, we engineer a self-pillared silicalite-1 nanosheet-supported Cu–Zn bimetallic catalyst to overcome these limitations. The hierarchically porous silicalite-1 architecture serves dual functions: (1) stabilizing highly dispersed Cu–Zn alloy interfaces and (2) inducing electronic modulation that synergistically enhances dissociative H2 chemisorption and spillover. Crucially, this interface imposes a stable η1-(O)-aldehyde adsorption configuration for both furfural and its furfuryl alcohol intermediate, effectively suppressing ring-hydrogenation-inducing flat η2-(C,O) adsorption modes. At a moderate 180 °C, this integrated catalyst design achieves a 2-methylfuran turnover frequency (TOF) of 20.6 h–1 with near-quantitative selectivity (99.2% yield) after one hour of reaction.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"41 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1021/acscatal.5c07065
Ivan Surin,Evgenii V. Kondratenko,Javier Pérez-Ramírez
Ammonia (NH3) oxidation to nitrous oxide (N2O) is a promising route to obtain this selective oxidant, but controlling product distribution is inherently challenging because N2O occupies an intermediate nitrogen oxidation state between N2 and NO. Despite recent advances, leading CeO2-based catalytic systems have consistently encountered a selectivity limit in the range of 80–85%. Herein, CeO2-supported Mn single atoms are employed as a stable, selective benchmark to investigate the origins of the N2O selectivity losses. Thorough kinetic analysis revealed that direct oxidation of NH3 to N2 is the main reason for incomplete N2O selectivity. This reaction dominates in a thin upstream catalyst bed layer, driven by its strong dependence on the NH3 partial pressure that ensures dense surface coverage by N-containing intermediates and promotes their irreversible coupling to N2. However, due to the inhibiting effect of H2O, this reaction is increasingly hindered along the catalyst bed, with N2O becoming the dominant product. Based on these insights, N2O selectivity could be increased from 81% to 90% while N2 selectivity decreased to 6% by water cofeeding and adjusting reactant partial pressures to tune surface coverage by N-containing intermediates. Evaluation of side reactions revealed a negligible impact of N2O decomposition or N2O reduction on product distribution. Conversely, employing isotopic tracing, reduction of in situ-formed NO by NH3 was established as a significant route to secondary N2O, and to a lesser extent, N2. This was shown to be a general feature of CeO2-based catalysts, including Mn, Au, and Cr systems, providing a lever for selectivity control. This work demonstrates how kinetic analysis can disentangle complex reaction pathways and identify both catalyst- and process-level strategies to advance NH3 oxidation to N2O beyond current limits.
{"title":"Origins of N2O Selectivity Limits in Catalyzed Ammonia Oxidation","authors":"Ivan Surin,Evgenii V. Kondratenko,Javier Pérez-Ramírez","doi":"10.1021/acscatal.5c07065","DOIUrl":"https://doi.org/10.1021/acscatal.5c07065","url":null,"abstract":"Ammonia (NH3) oxidation to nitrous oxide (N2O) is a promising route to obtain this selective oxidant, but controlling product distribution is inherently challenging because N2O occupies an intermediate nitrogen oxidation state between N2 and NO. Despite recent advances, leading CeO2-based catalytic systems have consistently encountered a selectivity limit in the range of 80–85%. Herein, CeO2-supported Mn single atoms are employed as a stable, selective benchmark to investigate the origins of the N2O selectivity losses. Thorough kinetic analysis revealed that direct oxidation of NH3 to N2 is the main reason for incomplete N2O selectivity. This reaction dominates in a thin upstream catalyst bed layer, driven by its strong dependence on the NH3 partial pressure that ensures dense surface coverage by N-containing intermediates and promotes their irreversible coupling to N2. However, due to the inhibiting effect of H2O, this reaction is increasingly hindered along the catalyst bed, with N2O becoming the dominant product. Based on these insights, N2O selectivity could be increased from 81% to 90% while N2 selectivity decreased to 6% by water cofeeding and adjusting reactant partial pressures to tune surface coverage by N-containing intermediates. Evaluation of side reactions revealed a negligible impact of N2O decomposition or N2O reduction on product distribution. Conversely, employing isotopic tracing, reduction of in situ-formed NO by NH3 was established as a significant route to secondary N2O, and to a lesser extent, N2. This was shown to be a general feature of CeO2-based catalysts, including Mn, Au, and Cr systems, providing a lever for selectivity control. This work demonstrates how kinetic analysis can disentangle complex reaction pathways and identify both catalyst- and process-level strategies to advance NH3 oxidation to N2O beyond current limits.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"53 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1021/acscatal.5c07220
Kinga Gołabek, Svetlana Kurucová, Juan Francisco Miñambres, Klára Veselá, Talat Zakeri, Jan Přech
Lewis acid zeolites, primarily Al-free Zr and Sn silicates, catalyze the chemoselective reduction of ketones and aldehydes to the corresponding alcohols through hydrogen transfer (Meerwein–Ponndorf–Verley (MPV) reduction). Sn silicates are more active in the MPV reduction of ketones, whereas Zr silicates are more active in the MPV reduction of aldehydes. However, the catalytic activity of these zeolites has not been accurately ascribed to “open” vs. “closed” Zr sites even though this correlation is crucial for systems whose substrate structure allows competing reaction pathways. For example, MPV reduction of citronellal competes with carbonyl-ene cyclization to isopulegol and acetalization in the citronellal reaction with 2-propanol. Therefore, we aimed to correlate thoroughly characterized Lewis acid sites in Zr-substituted beta and MFI zeolites with their selectivity. For this purpose, we analyzed Zr-zeolite acidity by fourier transform infrared spectroscopy (FTIR) spectroscopy of adsorbed deuterated acetonitrile and acetone because deuterated acetonitrile probes “open” Zr sites without interacting with “closed” sites, but acetone identifies both “open” and “closed” sites. Our results showed that Zr-beta rich in Zr “closed” sites favored MPV reduction. Conversely, Zr-beta rich in “open” sites and reference catalysts yielded isopulegol as the main product. Ion exchange of the Zr-beta “open” sites with Na+ cations deactivated these sites, thereby switching the selectivity to citronellol. In turn, the silanol groups of the catalyst promoted acetalization, regardless of substituting the heteroelement (Zr or Sn). These findings demonstrate that Zr-site Lewis acidity determines terpenoid reduction selectivity, as the relatively weaker Zr-beta “closed” sites catalyze citronellal MPV reduction to citronellol, while the relatively stronger Zr-beta “open” sites catalyze intramolecular carbonyl-ene cyclization to isopulegol. Moreover, this correlation between selectivity and Zr-site Lewis acidity may enable us to design specific catalysts, even for systems with competing reactions, based on quantitative data acquired using our experimental paradigm.
{"title":"Zr-Site Lewis Acidity Determines Terpenoid Reduction Selectivity","authors":"Kinga Gołabek, Svetlana Kurucová, Juan Francisco Miñambres, Klára Veselá, Talat Zakeri, Jan Přech","doi":"10.1021/acscatal.5c07220","DOIUrl":"https://doi.org/10.1021/acscatal.5c07220","url":null,"abstract":"Lewis acid zeolites, primarily Al-free Zr and Sn silicates, catalyze the chemoselective reduction of ketones and aldehydes to the corresponding alcohols through hydrogen transfer (Meerwein–Ponndorf–Verley (MPV) reduction). Sn silicates are more active in the MPV reduction of ketones, whereas Zr silicates are more active in the MPV reduction of aldehydes. However, the catalytic activity of these zeolites has not been accurately ascribed to “open” vs. “closed” Zr sites even though this correlation is crucial for systems whose substrate structure allows competing reaction pathways. For example, MPV reduction of citronellal competes with carbonyl-ene cyclization to isopulegol and acetalization in the citronellal reaction with 2-propanol. Therefore, we aimed to correlate thoroughly characterized Lewis acid sites in Zr-substituted beta and MFI zeolites with their selectivity. For this purpose, we analyzed Zr-zeolite acidity by fourier transform infrared spectroscopy (FTIR) spectroscopy of adsorbed deuterated acetonitrile and acetone because deuterated acetonitrile probes “open” Zr sites without interacting with “closed” sites, but acetone identifies both “open” and “closed” sites. Our results showed that Zr-beta rich in Zr “closed” sites favored MPV reduction. Conversely, Zr-beta rich in “open” sites and reference catalysts yielded isopulegol as the main product. Ion exchange of the Zr-beta “open” sites with Na<sup>+</sup> cations deactivated these sites, thereby switching the selectivity to citronellol. In turn, the silanol groups of the catalyst promoted acetalization, regardless of substituting the heteroelement (Zr or Sn). These findings demonstrate that Zr-site Lewis acidity determines terpenoid reduction selectivity, as the relatively weaker Zr-beta “closed” sites catalyze citronellal MPV reduction to citronellol, while the relatively stronger Zr-beta “open” sites catalyze intramolecular carbonyl-ene cyclization to isopulegol. Moreover, this correlation between selectivity and Zr-site Lewis acidity may enable us to design specific catalysts, even for systems with competing reactions, based on quantitative data acquired using our experimental paradigm.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"9 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1021/acscatal.5c07128
Xiaoru Wang,Zhanwu Lei,Jicong Yan,Penglong Wang,Ruifeng Chong,Fuping Tian,Tao Hu,Ruiguo Cao,Xiang Wang
Developing non-noble metal catalysts for hydrocracking polyolefins is a promising yet formidable challenge for upcycling waste plastics in practice. Herein, we report a NiW/WOx (2 < x < 3) catalyst, which accomplishes polyolefin hydrocracking at 250 °C, yielding a liquid product of about 73 wt % and a gaseous product of about 22 wt %. The liquid fraction primarily consists of hydrocarbons in the C4–C25 range, with more than 77% falling within the jet-fuel-range components (C8–C16). The gas product is dominated by branched C3–C6 hydrocarbons, characteristic of liquefied petroleum gas (LPG), with negligible carbon loss, such as methane and ethane.A sequence change from inactive to active, and back to inactive in polyolefin hydrocracking was found accompanying the reconstruction of the surface structure of the catalyst from Ni-doped WO3 to NiW alloy nanoparticles supported on WOx (NiW/WOx), and then to WO2-encapsulated NiW (NiW@WO2). The coexposure of NiW alloy nanoparticles and WOx is further demonstrated to be necessary for fulfilling the bifunctionality of the catalyst in hydrogen dissociation and C–C bond cleavage in polyolefin hydrocracking, and the absence of either will deactivate the catalyst.
{"title":"Hydrocracking Polyolefins to Jet Fuel over a NiW/WOx Catalyst","authors":"Xiaoru Wang,Zhanwu Lei,Jicong Yan,Penglong Wang,Ruifeng Chong,Fuping Tian,Tao Hu,Ruiguo Cao,Xiang Wang","doi":"10.1021/acscatal.5c07128","DOIUrl":"https://doi.org/10.1021/acscatal.5c07128","url":null,"abstract":"Developing non-noble metal catalysts for hydrocracking polyolefins is a promising yet formidable challenge for upcycling waste plastics in practice. Herein, we report a NiW/WOx (2 < x < 3) catalyst, which accomplishes polyolefin hydrocracking at 250 °C, yielding a liquid product of about 73 wt % and a gaseous product of about 22 wt %. The liquid fraction primarily consists of hydrocarbons in the C4–C25 range, with more than 77% falling within the jet-fuel-range components (C8–C16). The gas product is dominated by branched C3–C6 hydrocarbons, characteristic of liquefied petroleum gas (LPG), with negligible carbon loss, such as methane and ethane.A sequence change from inactive to active, and back to inactive in polyolefin hydrocracking was found accompanying the reconstruction of the surface structure of the catalyst from Ni-doped WO3 to NiW alloy nanoparticles supported on WOx (NiW/WOx), and then to WO2-encapsulated NiW (NiW@WO2). The coexposure of NiW alloy nanoparticles and WOx is further demonstrated to be necessary for fulfilling the bifunctionality of the catalyst in hydrogen dissociation and C–C bond cleavage in polyolefin hydrocracking, and the absence of either will deactivate the catalyst.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"108 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1021/acscatal.5c08001
Yingxiang Zhao,Yingjie Zhao,Xinyue Zhou,Haiwei Guo,Qiqi Yin,Yutao Jiang,Haiyan He,Na Liu,Gengbo Ren,Christopher M. A. Parlett,Changzhi Li
M–N–C single-atom catalysts (SACs) represent promising candidates owing to their atomically dispersed active sites and tunable catalytic properties and have shown broad potential in various catalysis reactions. However, the mechanisms and true active sites involved in lignin conversion, particularly oxidative depolymerization, remain unclear. Herein, a Ru–N–C SAC with a well-defined configuration, including coordination environment and coordination number, was synthesized via a straightforward ball-milling method for lignin oxidation. The Ru–N–C SAC prepared with 12 h of ball milling demonstrated high catalytic performance in the oxidative depolymerization of various β-O-4 model compounds and diverse lignin feedstocks. Structural analysis via X-ray absorption spectroscopy demonstrated that the Ru–N4 motif constitutes the predominant coordination environment in Ru–N–C, which is regarded as the primary active site in activating O2 into superoxide radicals, as confirmed by free-radical quenching experiments and electron paramagnetic resonance analysis; meanwhile, it also served as a basic site in polarizing Cβ–H bonds in β-O-4 that favored C–O/C–C bond cleavage, which was disclosed by CO2 temperature-programmed desorption and electron localization function analysis. The critical role of Ru–N4 in the activation of O2 and C–O/C–C bond cleavage was further confirmed by density functional theory calculation, which indicated that the Ru–N4 center exhibits strong adsorption toward both the O2 and β-O-4 linkages. This work provides a deep understanding on the active sites within Ru–N–C SACs for lignin oxidative cleavage and offers great potential on the rational design of next-generation SACs in biomass valorization.
{"title":"Unveiling the Role of Ru–N4 on Ru–N–C Single-Atom Catalyst in C–O/C–C Bonds’ Oxidative Cleavage in Lignin","authors":"Yingxiang Zhao,Yingjie Zhao,Xinyue Zhou,Haiwei Guo,Qiqi Yin,Yutao Jiang,Haiyan He,Na Liu,Gengbo Ren,Christopher M. A. Parlett,Changzhi Li","doi":"10.1021/acscatal.5c08001","DOIUrl":"https://doi.org/10.1021/acscatal.5c08001","url":null,"abstract":"M–N–C single-atom catalysts (SACs) represent promising candidates owing to their atomically dispersed active sites and tunable catalytic properties and have shown broad potential in various catalysis reactions. However, the mechanisms and true active sites involved in lignin conversion, particularly oxidative depolymerization, remain unclear. Herein, a Ru–N–C SAC with a well-defined configuration, including coordination environment and coordination number, was synthesized via a straightforward ball-milling method for lignin oxidation. The Ru–N–C SAC prepared with 12 h of ball milling demonstrated high catalytic performance in the oxidative depolymerization of various β-O-4 model compounds and diverse lignin feedstocks. Structural analysis via X-ray absorption spectroscopy demonstrated that the Ru–N4 motif constitutes the predominant coordination environment in Ru–N–C, which is regarded as the primary active site in activating O2 into superoxide radicals, as confirmed by free-radical quenching experiments and electron paramagnetic resonance analysis; meanwhile, it also served as a basic site in polarizing Cβ–H bonds in β-O-4 that favored C–O/C–C bond cleavage, which was disclosed by CO2 temperature-programmed desorption and electron localization function analysis. The critical role of Ru–N4 in the activation of O2 and C–O/C–C bond cleavage was further confirmed by density functional theory calculation, which indicated that the Ru–N4 center exhibits strong adsorption toward both the O2 and β-O-4 linkages. This work provides a deep understanding on the active sites within Ru–N–C SACs for lignin oxidative cleavage and offers great potential on the rational design of next-generation SACs in biomass valorization.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"106 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1021/acscatal.5c08026
Cristina Duran,Sílvia Osuna
The stand-alone version of the alpha subunit of tryptophan synthase (TrpA), ZmBX1, catalyzes the retro-aldol cleavage of indole-3-glycerol phosphate (IGP) at a catalytic efficiency that is approximately 144,000 times higher than that of isolated ZmTrpA. Available X-ray crystal structures of ZmBX1 and several TrpAs revealed identical overall structures as well as active site geometries, showing high flexibility of the catalytic E49 in both cases. Based on the crystallographic data, E49 was found to adopt an active state in which the carboxylate group is close to IGP for promoting the retro-aldol cleavage as well as an additional inactive state whose catalytic function was unclear. In this work, by using a combination of Molecular Dynamics (MD) simulations and cluster model DFT calculations, we rationalize the effect of the active/inactive conformation of the catalytic E49, as well as how L2 containing the other catalytically relevant residue D60 affects catalysis. The higher levels of retro-aldol activity observed for ZmBX1 are attributed to its dual ability to adopt not only active states of the catalytic E49 crucial for retro-aldol cleavage but also inactive states that position E49 in a noncatalytic orientation for disfavoring the reverse aldol reaction back to IGP after product formation. Our combined MD and QM studies elucidate the mechanistic interplay between conformational changes and catalytic steps in ZmBX1 and TrpA enzymes. This study highlights the importance of optimizing the conformational changes and chemical steps along the catalytic itinerary for altering and/or improving enzymatic function.
{"title":"Inactive but Essential: The Role of the Inactive State of E49 in the Mechanism of the Alpha Subunit of Tryptophan Synthase and Its Stand-Alone Blueprint ZmBX1","authors":"Cristina Duran,Sílvia Osuna","doi":"10.1021/acscatal.5c08026","DOIUrl":"https://doi.org/10.1021/acscatal.5c08026","url":null,"abstract":"The stand-alone version of the alpha subunit of tryptophan synthase (TrpA), ZmBX1, catalyzes the retro-aldol cleavage of indole-3-glycerol phosphate (IGP) at a catalytic efficiency that is approximately 144,000 times higher than that of isolated ZmTrpA. Available X-ray crystal structures of ZmBX1 and several TrpAs revealed identical overall structures as well as active site geometries, showing high flexibility of the catalytic E49 in both cases. Based on the crystallographic data, E49 was found to adopt an active state in which the carboxylate group is close to IGP for promoting the retro-aldol cleavage as well as an additional inactive state whose catalytic function was unclear. In this work, by using a combination of Molecular Dynamics (MD) simulations and cluster model DFT calculations, we rationalize the effect of the active/inactive conformation of the catalytic E49, as well as how L2 containing the other catalytically relevant residue D60 affects catalysis. The higher levels of retro-aldol activity observed for ZmBX1 are attributed to its dual ability to adopt not only active states of the catalytic E49 crucial for retro-aldol cleavage but also inactive states that position E49 in a noncatalytic orientation for disfavoring the reverse aldol reaction back to IGP after product formation. Our combined MD and QM studies elucidate the mechanistic interplay between conformational changes and catalytic steps in ZmBX1 and TrpA enzymes. This study highlights the importance of optimizing the conformational changes and chemical steps along the catalytic itinerary for altering and/or improving enzymatic function.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"8 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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