The paper reports on the use of heterogeneous supported Cu catalysts in the aqueous phase reduction of mono and disaccharides to reduced sugars. The huge availability of the starting materials present also in many side streams of the agri-food industry and the growing interest in polyols not only in the food and pharma sectors but also in the polymer one make this reaction a relevant one in the current scenario. Although less active than Ru and Ni based ones, low loaded Cu catalysts show very interesting performance. Conversions up to 100 % can be reached in the hydrogenation of galactose at 160°C and 40 bar of H2. Moreover, they allow to directly obtain reduced sugars in the hydrogenation of disaccharides through a one pot bifunctional hydrolysis-hydrogenation process. The high dispersion of the Cu metallic phase and the presence of weak acidic sites on the catalyst surface can give account of the observed activity and selectivity.
{"title":"The peculiar role of copper in the saccharides hydrogenation in aqueous phase","authors":"Federica Zaccheria , Léa Vilcocq , Valeria Pappalardo , Nicola Scotti , Nicoletta Ravasio","doi":"10.1016/j.cattod.2024.115135","DOIUrl":"10.1016/j.cattod.2024.115135","url":null,"abstract":"<div><div>The paper reports on the use of heterogeneous supported Cu catalysts in the aqueous phase reduction of mono and disaccharides to reduced sugars. The huge availability of the starting materials present also in many side streams of the agri-food industry and the growing interest in polyols not only in the food and pharma sectors but also in the polymer one make this reaction a relevant one in the current scenario. Although less active than Ru and Ni based ones, low loaded Cu catalysts show very interesting performance. Conversions up to 100 % can be reached in the hydrogenation of galactose at 160°C and 40 bar of H<sub>2</sub>. Moreover, they allow to directly obtain reduced sugars in the hydrogenation of disaccharides through a one pot bifunctional hydrolysis-hydrogenation process. The high dispersion of the Cu metallic phase and the presence of weak acidic sites on the catalyst surface can give account of the observed activity and selectivity.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115135"},"PeriodicalIF":5.2,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.cattod.2024.115124
Mrinal Kanti Adak, Hirak Kumar Basak, Biswarup Chakraborty
Electrokinetic analyses harnessing intrinsic reaction parameters of the electrocatalytic oxygen evolution reaction (OER) shed light on the reaction mechanism. Given the superior stability of the iron oxy-hydroxide under alkaline OER conditions, α-FeO(OH) and γ-FeO(OH) are often found to be the active catalyst. Herein, nanocrystalline α-FeO(OH) and γ-FeO(OH) materials are used as catalysts to perform alkaline OER and detailed electrokinetic studies are conducted to establish the reaction pathway. The intrinsic parameters like anodic transfer coefficient (αa), specific exchange current density (j0,s), activation energy (), and reaction order (m) are experimentally determined for both FeO(OH) phases. To obtain these important parameters, OER is performed with α-FeO(OH) and γ-FeO(OH) deposited on nickel foam as anode while varying the cell temperature from 298 K to 343 K and electrolyte concentrations from 0.05 M to 2.0 M KOH. The j0,s values for α-FeO(OH) and γ-FeO(OH) are almost comparable 2.5 ± 0.5 × 10−3 mA cm−2 highlighting a similar rate of electron transfer. The activation energy barrier for OER on α-FeO(OH) and γ-FeO(OH) is identified to be 9.45 kJ mol−1 and 8.06 kJ mol−1, respectively and the values are manyfold less compared to that observed for previously reported IrO2 or NiFeOx materials emphasizing a faster kinetics on the FeO(OH) surface. The first-order reaction is determined from the electrolyte concentration variation suggesting the dissociation of O-H could be the rate-determining step (RDS) which is contrary to the mechanism proposed for IrO2 or NiFeOx where the O-O bond formation was found to be rate-limiting. Extracting the intrinsic reaction parameters from the electro-kinetics study, the OER pathway on the FeO(OH) surface has been established here.
利用电催化氧进化反应（OER）的内在反应参数进行的电动力学分析揭示了反应机理。鉴于氢氧化铁在碱性 OER 条件下具有优异的稳定性，α-FeO(OH) 和 γ-FeO(OH)通常被认为是活性催化剂。本文以纳米晶α-FeO(OH)和γ-FeO(OH)材料为催化剂进行碱性 OER，并进行了详细的电动力学研究以确定反应途径。实验测定了两种 FeO（OH）相的阳极传递系数（αa）、比交换电流密度（j0,s）、活化能（Ea0）和反应顺序（m）等内在参数。为了获得这些重要参数，我们使用沉积在泡沫镍阳极上的α-FeO(OH) 和 γ-FeO(OH)进行了 OER，同时将电池温度从 298 K 调整到 343 K，电解质浓度从 0.05 M 调整到 2.0 M KOH。α-FeO(OH)和γ-FeO(OH)的 j0,s 值几乎相等，均为 2.5 ± 0.5 × 10-3 mA cm-2，表明电子转移率相似。α-FeO(OH)和γ-FeO(OH)上 OER 的活化能势垒分别为 9.45 kJ mol-1 和 8.06 kJ mol-1，与之前报道的 IrO2 或 NiFeOx 材料上的活化能势垒相比小了很多倍，这表明 FeO(OH)表面的动力学速度更快。根据电解质浓度变化确定的一阶反应表明，O-H 的解离可能是速率决定步骤 (RDS)，这与针对 IrO2 或 NiFeOx 提出的机制相反，后者发现 O-O 键的形成是速率限制因素。通过从电动力学研究中提取内在反应参数，本文确定了 FeO（OH）表面的 OER 途径。
{"title":"Establishing the oxygen evolution reaction pathway on iron-oxy-hydroxide through electro-kinetic study","authors":"Mrinal Kanti Adak, Hirak Kumar Basak, Biswarup Chakraborty","doi":"10.1016/j.cattod.2024.115124","DOIUrl":"10.1016/j.cattod.2024.115124","url":null,"abstract":"<div><div>Electrokinetic analyses harnessing intrinsic reaction parameters of the electrocatalytic oxygen evolution reaction (OER) shed light on the reaction mechanism. Given the superior stability of the iron oxy-hydroxide under alkaline OER conditions, α-FeO(OH) and γ-FeO(OH) are often found to be the active catalyst. Herein, nanocrystalline α-FeO(OH) and γ-FeO(OH) materials are used as catalysts to perform alkaline OER and detailed electrokinetic studies are conducted to establish the reaction pathway. The intrinsic parameters like anodic transfer coefficient (α<sub>a</sub>), specific exchange current density (j<sub>0,s</sub>), activation energy (<span><math><msubsup><mrow><mi>E</mi></mrow><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow></msubsup></math></span>), and reaction order (m) are experimentally determined for both FeO(OH) phases. To obtain these important parameters, OER is performed with α-FeO(OH) and γ-FeO(OH) deposited on nickel foam as anode while varying the cell temperature from 298 K to 343 K and electrolyte concentrations from 0.05 M to 2.0 M KOH. The <em>j</em><sub><em>0,s</em></sub> values for α-FeO(OH) and γ-FeO(OH) are almost comparable 2.5 ± 0.5 × 10<sup>−3</sup> mA cm<sup>−2</sup> highlighting a similar rate of electron transfer. The activation energy barrier for OER on α-FeO(OH) and γ-FeO(OH) is identified to be 9.45 kJ mol<sup>−1</sup> and 8.06 kJ mol<sup>−1</sup>, respectively and the values are manyfold less compared to that observed for previously reported IrO<sub>2</sub> or NiFeO<sub>x</sub> materials emphasizing a faster kinetics on the FeO(OH) surface. The first-order reaction is determined from the electrolyte concentration variation suggesting the dissociation of O-H could be the rate-determining step (RDS) which is contrary to the mechanism proposed for IrO<sub>2</sub> or NiFeO<sub>x</sub> where the O-O bond formation was found to be rate-limiting. Extracting the intrinsic reaction parameters from the electro-kinetics study, the OER pathway on the FeO(OH) surface has been established here.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115124"},"PeriodicalIF":5.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.cattod.2024.115115
Lorena T. Pérez-Poyatos, Sergio Morales-Torres, Luisa M. Pastrana-Martínez, Francisco J. Maldonado-Hódar
The performance of carbon xerogel/TiO2 composites in ethylene photo-oxidation was analyzed under dynamic conditions considering various parameters, namely sulfur doping, dry vs. humid conditions and type of radiation (ultraviolet, UV, vs. visible light, Vis). The catalysts were synthesized using an acid-catalyzed sol-gel process and characterized with complementary techniques, including SEM/EDX, XRD, XPS and physical adsorption of N2 and CO2, among others. The performance of samples in ethylene removal by adsorption and photo-oxidation under dynamic flow was discussed and related with their physicochemical properties and the experimental conditions. Although ethylene adsorption was hindered by doping and humidity, both factors were found to enhance photoactivity by promoting the formation of highly oxidant hydroxyl radicals (HO•). The composites showed an improved catalytic performance compared to bare TiO2, with sulfur improving the activity by approximately 8 %. The presence of the carbon material also enhanced the performance under Vis radiation by nearly 25 %. It was suggested that sulfur species could migrate from the carbon support to the TiO2 nanoparticles during carbonization, forming Ti-O-S bonds. This finding constitutes a novel, cost-effective, sustainable and scalable method for the preparation of supported and doped TiO2 nanocomposites.
考虑到各种参数，即硫掺杂、干燥与潮湿条件以及辐射类型（紫外线与可见光），在动态条件下分析了碳 xerogel/TiO2 复合材料在乙烯光氧化中的性能。催化剂采用酸催化溶胶-凝胶工艺合成，并通过 SEM/EDX、XRD、XPS 以及 N2 和 CO2 物理吸附等辅助技术进行表征。讨论了样品在动态流动条件下通过吸附和光氧化去除乙烯的性能，并将其与样品的理化性质和实验条件联系起来。虽然掺杂和湿度阻碍了乙烯的吸附，但这两个因素都促进了高氧化性羟基自由基（HO-）的形成，从而提高了光活性。与裸 TiO2 相比，复合材料的催化性能有所提高，其中硫的活性提高了约 8%。碳材料的存在也将 Vis 辐射下的性能提高了近 25%。研究表明，在碳化过程中，硫元素可从碳支撑迁移到二氧化钛纳米颗粒，形成 Ti-O-S 键。这一发现为制备支撑和掺杂二氧化钛纳米复合材料提供了一种新颖、经济、可持续和可扩展的方法。
{"title":"Sulfur-doped carbon/TiO2 composites for ethylene photo-oxidation. Enhanced performance by doping TiO2 phases with sulfur by mobile species inserted on the carbon support","authors":"Lorena T. Pérez-Poyatos, Sergio Morales-Torres, Luisa M. Pastrana-Martínez, Francisco J. Maldonado-Hódar","doi":"10.1016/j.cattod.2024.115115","DOIUrl":"10.1016/j.cattod.2024.115115","url":null,"abstract":"<div><div>The performance of carbon xerogel/TiO<sub>2</sub> composites in ethylene photo-oxidation was analyzed under dynamic conditions considering various parameters, namely sulfur doping, dry <em>vs.</em> humid conditions and type of radiation (ultraviolet, UV, <em>vs.</em> visible light, Vis). The catalysts were synthesized using an acid-catalyzed sol-gel process and characterized with complementary techniques, including SEM/EDX, XRD, XPS and physical adsorption of N<sub>2</sub> and CO<sub>2</sub>, among others. The performance of samples in ethylene removal by adsorption and photo-oxidation under dynamic flow was discussed and related with their physicochemical properties and the experimental conditions. Although ethylene adsorption was hindered by doping and humidity, both factors were found to enhance photoactivity by promoting the formation of highly oxidant hydroxyl radicals (HO<sup>•</sup>). The composites showed an improved catalytic performance compared to bare TiO<sub>2</sub>, with sulfur improving the activity by approximately 8 %. The presence of the carbon material also enhanced the performance under Vis radiation by nearly 25 %. It was suggested that sulfur species could migrate from the carbon support to the TiO<sub>2</sub> nanoparticles during carbonization, forming Ti-O-S bonds. This finding constitutes a novel, cost-effective, sustainable and scalable method for the preparation of supported and doped TiO<sub>2</sub> nanocomposites.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115115"},"PeriodicalIF":5.2,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-06DOI: 10.1016/j.cattod.2024.115118
Mariana V. Rodrigues , Paloma Vinaches , Carla C. Polo , Marlon M. Silva , Ana F. Suzana , Wonsuk Cha , Sibele B. Pergher , Amélie Rochet , Florian Meneau
Zeolites exhibit framework flexibility driving their chemical and catalytic properties. Since the zeolitic pores are extremely small, a slight strain generated in the crystal induces compelling changes in shape, connectivity, accessibility, and the framework chemical properties. These modifications affected the adsorption and desorption of reactants/products and the diffusion within the channels during reaction. Using in situ 3D Bragg coherent X-ray diffraction imaging, we unveil the dynamics of the zeolite structure during catalysis, contraction and/or expansion of its framework also known as zeolite framework flexibility. We imaged three-dimensionally a single faujasite zeolite crystal during the ethanol dehydration reaction revealing anisotropic lattice dynamics simultaneously to guest molecules formation. Understanding zeolite flexibility could permit to tune zeolites properties towards potentially higher adsorption and selectivity.
沸石在化学和催化特性方面表现出框架灵活性。由于沸石孔隙极小，晶体中产生的微小应变就会引起形状、连通性、通达性和框架化学特性的显著变化。这些变化影响了反应物/产物的吸附和解吸以及反应过程中通道内的扩散。利用原位三维布拉格相干 X 射线衍射成像技术，我们揭示了沸石结构在催化过程中的动态变化、其框架的收缩和/或扩张（也称为沸石框架的灵活性）。我们对乙醇脱水反应过程中的单个faujasite沸石晶体进行了三维成像，发现在客体分子形成的同时，晶格也发生了各向异性的动态变化。了解沸石的柔性可以调整沸石的特性，从而提高吸附性和选择性。
{"title":"In situ visualisation of zeolite anisotropic framework flexibility during catalysis","authors":"Mariana V. Rodrigues , Paloma Vinaches , Carla C. Polo , Marlon M. Silva , Ana F. Suzana , Wonsuk Cha , Sibele B. Pergher , Amélie Rochet , Florian Meneau","doi":"10.1016/j.cattod.2024.115118","DOIUrl":"10.1016/j.cattod.2024.115118","url":null,"abstract":"<div><div>Zeolites exhibit framework flexibility driving their chemical and catalytic properties. Since the zeolitic pores are extremely small, a slight strain generated in the crystal induces compelling changes in shape, connectivity, accessibility, and the framework chemical properties. These modifications affected the adsorption and desorption of reactants/products and the diffusion within the channels during reaction. Using <em>in situ</em> 3D Bragg coherent X-ray diffraction imaging, we unveil the dynamics of the zeolite structure during catalysis, contraction and/or expansion of its framework also known as zeolite framework flexibility. We imaged three-dimensionally a single faujasite zeolite crystal during the ethanol dehydration reaction revealing anisotropic lattice dynamics simultaneously to guest molecules formation. Understanding zeolite flexibility could permit to tune zeolites properties towards potentially higher adsorption and selectivity.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115118"},"PeriodicalIF":5.2,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Plastic waste generation has become a global issue and presents a significant challenge concerning degradability in the environment. This poses a serious threat and adverse impact on the health of living creature and the environment ecosystem. The up-/re-cycling of plastic waste through catalytic depolymerization is becoming a sustainable way to reduce economic concerns about production and serious environmental impacts. Here, in the present study an effort has been made for the development of catalysts for efficient recycling of carbonyl group containing polymer waste [Polyethylene terephthalate (PET) and polycarbonate (PC)]. The sequential preparation of ZnMIV- and ZnAlMIV- LDHs (layered double hydroxides) (MIV= Zr and Ti) and their respective mixed metal oxide (MMOs) based catalytic materials, has been carried out by one-pot co-precipitation and calcination methods. The structural parameters were examined through the various characterisation techniques including XRD, FTIR, TEM, SEM, and EDS. The layered structure, high crystalline nature and hexagonal 2D-sheet/flakes like morphology with average particle size ranging from ∼14–51 nm [for LDHs] and ∼6–21 nm [for MMOs] were observed. Depolymerization of PET and PC using LDHs/MMOs catalyst in ethylene glycols (EG) produced bis(2-hydroxyethyl terephthalate) (BHET) and bisphenol A (BPA) monomers as main products, respectively. The catalyst quantity, concentration of solvent, recyclability of catalysts, reaction duration, and crystallization time have also been further investigated for better yield during catalytic glycolysis. The isolated monomers were further characterized by using melting point, mass spectroscopy, 1H NMR, 13C NMR and FTIR analysis. The order of catalytic activities of prepared samples as ZnTi-LDH˃ ZnAlTi-LDH ˃ ZnTi-MMO˃ ZnAlZr-LDH˃ ZnAlTi-MMO˃ ZnZr-LDH in PET depolymerization while in case of PC, the order as ZnTi-LDH˃ ZnAlTi-LDH ˃ ZnZr-LDH˃ ZnAlZr-LDH˃ ZnZr-MMO˃ ZnAlZr-MMO˃ ZnTi-MMO˃ ZnAlTi-MMO were observed. LDH samples showed higher catalytic conversion than their respective MMOs during PET and PC depolymerization into monomers BHET and BPA with % yield of ∼76–83 % and ∼81–89 %, respectively. ZnTi-LDH shows high catalytic efficacy in depolymerization of PET and PC with yield of (∼82 %) BHET monomer and (89 %) BPA. This catalyst displayed good recyclability more than eight cycles during this catalytic glycolysis study.
{"title":"Tetravalent metals modulated Zn-based layered double hydroxides and their mixed metal oxides for catalytic depolymerization of carbonyl-coordinating plastic waste","authors":"Savita Soni , Sonika Kumari , Ajay Sharma , Shashi Kant Bhatia , Anil Kumar Sharma","doi":"10.1016/j.cattod.2024.115136","DOIUrl":"10.1016/j.cattod.2024.115136","url":null,"abstract":"<div><div>Plastic waste generation has become a global issue and presents a significant challenge concerning degradability in the environment. This poses a serious threat and adverse impact on the health of living creature and the environment ecosystem. The up-/re-cycling of plastic waste through catalytic depolymerization is becoming a sustainable way to reduce economic concerns about production and serious environmental impacts. Here, in the present study an effort has been made for the development of catalysts for efficient recycling of carbonyl group containing polymer waste [Polyethylene terephthalate (PET) and polycarbonate (PC)]. The sequential preparation of ZnM<sup>IV</sup>- and ZnAlM<sup>IV</sup>- LDHs (layered double hydroxides) (M<sup>IV</sup>= Zr and Ti) and their respective mixed metal oxide (MMOs) based catalytic materials, has been carried out by one-pot co-precipitation and calcination methods. The structural parameters were examined through the various characterisation techniques including XRD, FTIR, TEM, SEM, and EDS. The layered structure, high crystalline nature and hexagonal 2D-sheet/flakes like morphology with average particle size ranging from ∼14–51 nm [for LDHs] and ∼6–21 nm [for MMOs] were observed. Depolymerization of PET and PC using LDHs/MMOs catalyst in ethylene glycols (EG) produced bis(2-hydroxyethyl terephthalate) (BHET) and bisphenol A (BPA) monomers as main products, respectively. The catalyst quantity, concentration of solvent, recyclability of catalysts, reaction duration, and crystallization time have also been further investigated for better yield during catalytic glycolysis. The isolated monomers were further characterized by using melting point, mass spectroscopy, <sup>1</sup>H NMR, <sup>13</sup>C NMR and FTIR analysis. The order of catalytic activities of prepared samples as ZnTi-LDH˃ ZnAlTi-LDH ˃ ZnTi-MMO˃ ZnAlZr-LDH˃ ZnAlTi-MMO˃ ZnZr-LDH in PET depolymerization while in case of PC, the order as ZnTi-LDH˃ ZnAlTi-LDH ˃ ZnZr-LDH˃ ZnAlZr-LDH˃ ZnZr-MMO˃ ZnAlZr-MMO˃ ZnTi-MMO˃ ZnAlTi-MMO were observed. LDH samples showed higher catalytic conversion than their respective MMOs during PET and PC depolymerization into monomers BHET and BPA with % yield of ∼76–83 % and ∼81–89 %, respectively. ZnTi-LDH shows high catalytic efficacy in depolymerization of PET and PC with yield of (∼82 %) BHET monomer and (89 %) BPA. This catalyst displayed good recyclability more than eight cycles during this catalytic glycolysis study.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115136"},"PeriodicalIF":5.2,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.cattod.2024.115123
Tanmoy Ghosh , Imran Khan , Subhajit Saha
Traditionally, photocatalysts have been considered as effective tool to combat water pollution caused by Cr(VI) contamination. However, absence of sunlight in night and poor transmittance in the waste water restrict their wide-spread practical applications. Herein, two dimensional MoS2 nanosheets have been employed as pyrocatalyst for round-o-clock utilization of natural temperature fluctuation and consequent reduction of Cr(VI). MoS2 pyrocatalysts have been synthesized via facile hydrothermal technique and further characterized by XRD, XPS, SEM technique. The developed pyrocatalyst exhibits ∼95 % removal of 80 ppm Cr(VI) under thermal cycles between 20 ºC and 70 ºC. Moreover, the pyrocatalyst can effectively harness natural temperature variation for the catalytic reduction of Cr(VI) in just 30 days. The excited electrons generated during the temperature variation are identified as active species responsible for Cr(VI) reduction. The results and concept presented here may bring new possibilities for the removal of heavy metal ions in waste water treatment technology.
{"title":"Pyrocatalytic removal of Cr(VI) by MoS2 nanosheets under controlled thermal fluctuation","authors":"Tanmoy Ghosh , Imran Khan , Subhajit Saha","doi":"10.1016/j.cattod.2024.115123","DOIUrl":"10.1016/j.cattod.2024.115123","url":null,"abstract":"<div><div>Traditionally, photocatalysts have been considered as effective tool to combat water pollution caused by Cr(VI) contamination. However, absence of sunlight in night and poor transmittance in the waste water restrict their wide-spread practical applications. Herein, two dimensional MoS<sub>2</sub> nanosheets have been employed as pyrocatalyst for round-o-clock utilization of natural temperature fluctuation and consequent reduction of Cr(VI). MoS<sub>2</sub> pyrocatalysts have been synthesized via facile hydrothermal technique and further characterized by XRD, XPS, SEM technique. The developed pyrocatalyst exhibits ∼95 % removal of 80 ppm Cr(VI) under thermal cycles between 20 ºC and 70 ºC. Moreover, the pyrocatalyst can effectively harness natural temperature variation for the catalytic reduction of Cr(VI) in just 30 days. The excited electrons generated during the temperature variation are identified as active species responsible for Cr(VI) reduction. The results and concept presented here may bring new possibilities for the removal of heavy metal ions in waste water treatment technology.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115123"},"PeriodicalIF":5.2,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.cattod.2024.115121
Jussara V.R. Vieira, Tassia C.P. Pereira, Carlos H.F. da Cunha, Davi D. Petrolini, Ana C.M. Tello, Alice M. Lima, Yasmin O. Carvalho, André L.R. Garcia, Ernesto A. Urquieta-Gonzalez, João B.O. dos Santos, Patrícia M. Lima, José M.C. Bueno
Methane oxidation to methanol in cyclic processes using CuO-zeolites has traditionally employed O2 and N2O as oxidants. This study explores the use of Cu-CHA zeolite, demonstrating that CO2 can substitute O2 in an isothermal reaction at 400 °C, analogous to previous findings using Cu-MAZ. The use of in situ UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and density functional theory (DFT) theoretical calculations identified the formation of a binuclear copper hydroxide complex, Z-[CuOH-HOCu]2+-Z, on the Cu-CHA. Initial treatment using CO2 led to marginally superior catalytic activity, compared to the use of O2 alone, indicating the stability of the Z-[CuOH-HOCu]2+-Z complex against self-reduction at 400 °C. In subsequent cycles, activation with O2 facilitated the oxidation of adsorbed methanol, yielding water and reconstituting the active sites. Conversely, activation with CO2 led to the partial desorption of methanol, precluding water production and subsequent catalyst regeneration. The findings suggested that both O2 and CO2 activations necessitated a post-reaction water extraction step, followed by thermal treatment to replenish the active sites. Importantly, the results indicated that CO2 could be used as a viable alternative oxidant to O2 in this catalytic process, potentially enhancing the sustainability of industrial methanol production.
在使用 CuO-zeolites 的循环过程中，甲烷氧化成甲醇的过程传统上使用 O2 和 N2O 作为氧化剂。本研究探索了 Cu-CHA 沸石的使用，证明在 400 °C 的等温反应中 CO2 可以替代 O2，这与之前使用 Cu-MAZ 的研究结果类似。利用原位紫外可见光漫反射光谱（UV-Vis DRS）和密度泛函理论（DFT）理论计算确定了在 Cu-CHA 上形成的双核氢氧化铜复合物 Z-[CuOH-HOCu]2+-Z。与单独使用 O2 相比，使用 CO2 进行初始处理可略微提高催化活性，这表明 Z-[CuOH-HOCu]2+-Z 复合物在 400 °C 温度下具有抗自还原的稳定性。在随后的循环中，用 O2 活化可促进吸附的甲醇氧化，生成水并重组活性位点。相反，用 CO2 激活则会导致部分甲醇解吸，从而排除水的生成和催化剂的后续再生。研究结果表明，氧气和二氧化碳活化都需要在反应后进行水提取步骤，然后再进行热处理以补充活性位点。重要的是，研究结果表明，在这一催化过程中，二氧化碳可用作氧气的替代氧化剂，从而有可能提高工业甲醇生产的可持续性。
{"title":"Isothermal conversion of methane to methanol over Cu-CHA using different oxidants","authors":"Jussara V.R. Vieira, Tassia C.P. Pereira, Carlos H.F. da Cunha, Davi D. Petrolini, Ana C.M. Tello, Alice M. Lima, Yasmin O. Carvalho, André L.R. Garcia, Ernesto A. Urquieta-Gonzalez, João B.O. dos Santos, Patrícia M. Lima, José M.C. Bueno","doi":"10.1016/j.cattod.2024.115121","DOIUrl":"10.1016/j.cattod.2024.115121","url":null,"abstract":"<div><div>Methane oxidation to methanol in cyclic processes using CuO-zeolites has traditionally employed O<sub>2</sub> and N<sub>2</sub>O as oxidants. This study explores the use of Cu-CHA zeolite, demonstrating that CO<sub>2</sub> can substitute O<sub>2</sub> in an isothermal reaction at 400 °C, analogous to previous findings using Cu-MAZ. The use of <em>in situ</em> UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and density functional theory (DFT) theoretical calculations identified the formation of a binuclear copper hydroxide complex, Z-[CuOH-HOCu]<sup>2+</sup>-Z, on the Cu-CHA. Initial treatment using CO<sub>2</sub> led to marginally superior catalytic activity, compared to the use of O<sub>2</sub> alone, indicating the stability of the Z-[CuOH-HOCu]<sup>2+</sup>-Z complex against self-reduction at 400 °C. In subsequent cycles, activation with O<sub>2</sub> facilitated the oxidation of adsorbed methanol, yielding water and reconstituting the active sites. Conversely, activation with CO<sub>2</sub> led to the partial desorption of methanol, precluding water production and subsequent catalyst regeneration. The findings suggested that both O<sub>2</sub> and CO<sub>2</sub> activations necessitated a post-reaction water extraction step, followed by thermal treatment to replenish the active sites. Importantly, the results indicated that CO<sub>2</sub> could be used as a viable alternative oxidant to O<sub>2</sub> in this catalytic process, potentially enhancing the sustainability of industrial methanol production.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115121"},"PeriodicalIF":5.2,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogen and oxygen production from electrocatalytic water splitting offers a sustainable strategy towards achieving renewable energy. However, sluggish kinetics of the reaction require expensive platinum (Pt) and ruthenium dioxide (RuO2)/ iridium dioxide (IrO2)-based electrocatalysts where the high cost of the catalyst hinders the practical use of water splitting reaction. Two-dimensional mixed metal metal-organic frameworks (2D MM-MOFs) have emerged as alternative promising electrocatalysts. In MM-MOFs, the metal centers play a crucial role in determining the catalytic activity. Among several MM-MOFs explored for water splitting reaction, Co(II) and Ni(II)-based MM-MOFs have shown a significant potential, rendering them as promising materials for efficient and sustainable electrochemical energy conversion and storage technologies. Herein, we highlight recent advancements in the development of Ni(II) and Co(II)-based 2D MM-MOFs, emphasizing their outstanding electrocatalytic performance for hydrogen evolution reaction and oxygen evolution reaction. Strategies for the effective design and development of electrocatalysts along with the challenges are also discussed.
{"title":"Nickel (II) and Cobalt (II) Based 2D mixed metal-metal organic frameworks (MM-MOFs) for electrocatalytic water splitting reactions","authors":"Janak, Ritika Jaryal, Sakshi, Rakesh Kumar, Sadhika Khullar","doi":"10.1016/j.cattod.2024.115117","DOIUrl":"10.1016/j.cattod.2024.115117","url":null,"abstract":"<div><div>Hydrogen and oxygen production from electrocatalytic water splitting offers a sustainable strategy towards achieving renewable energy. However, sluggish kinetics of the reaction require expensive platinum (Pt) and ruthenium dioxide (RuO<sub>2</sub>)/ iridium dioxide (IrO<sub>2</sub>)-based electrocatalysts where the high cost of the catalyst hinders the practical use of water splitting reaction. Two-dimensional mixed metal metal-organic frameworks (2D MM-MOFs) have emerged as alternative promising electrocatalysts. In MM-MOFs, the metal centers play a crucial role in determining the catalytic activity. Among several MM-MOFs explored for water splitting reaction, Co(II) and Ni(II)-based MM-MOFs have shown a significant potential, rendering them as promising materials for efficient and sustainable electrochemical energy conversion and storage technologies. Herein, we highlight recent advancements in the development of Ni(II) and Co(II)-based 2D MM-MOFs, emphasizing their outstanding electrocatalytic performance for hydrogen evolution reaction and oxygen evolution reaction. Strategies for the effective design and development of electrocatalysts along with the challenges are also discussed.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115117"},"PeriodicalIF":5.2,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.cattod.2024.115105
Sneha R. Shetty , Ganapati D. Yadav
Hydrogenation of xylose to xylitol is commercially attractive. The use of water as well as aqueous isopropanol as solvent using a novel robust catalyst was targeted in this work. This work showed that a nickel-alumina catalyst supported on hexagonal mesoporous silica (HMS) can effectively transform lignocellulose-derived xylose fraction to the value-added product, xylitol. HMS support was modified by simultaneous impregnating nickel (6 wt%) and alumina (4 wt%) which was subsequently oxidized. The catalyst was evaluated for its hydrogenation ability of xylose to xylitol. Identical reactions were carried out with HMS, alumina, Al/HMS and Ni/HMS to ascertain the activity of each moiety in the reaction. Before the reaction, the catalyst was reduced in a tubular reactor in the presence of hydrogen. Reaction parameters such as speed of agitation, type of precursor, metal loading, catalyst loading, solvent, concentration and temperature were studied and optimized. At 130℃ and 20 bar H2, initial xylose concentration of 0.2 mmol/mL with water: isopropanol (1:1 v/v) mixture as solvent, conversion of xylose was found to be 98 % with a selectivity of 97 % towards xylitol. Comparison was also made with water alone as a solvent. A kinetic study of the reaction was performed. The transformation of xylose to xylitol using this novel catalyst is a green process since it entails substantially lower metal loading when compared to the conventional Raney nickel catalysts, it does not involve the use of noble metals such as Pt, Pd, Rh or Ru, and also does not suffer from the problem of metal leaching, making it superior to those catalysts reported yet.
将木糖加氢转化为木糖醇具有商业吸引力。本研究以水和异丙醇水溶液为溶剂，并使用新型强效催化剂为目标。这项研究表明，六方介孔二氧化硅（HMS）支撑的镍-氧化铝催化剂可以有效地将木质纤维素衍生的木糖部分转化为高附加值产品木糖醇。通过同时浸渍镍（6 wt%）和氧化铝（4 wt%）对 HMS 载体进行改性，然后对其进行氧化。对该催化剂将木糖氢化为木糖醇的能力进行了评估。用 HMS、氧化铝、Al/HMS 和 Ni/HMS 进行了相同的反应，以确定每个分子在反应中的活性。反应前，催化剂在有氢气存在的管式反应器中进行还原。对搅拌速度、前驱体类型、金属负载、催化剂负载、溶剂、浓度和温度等反应参数进行了研究和优化。在 130℃ 和 20 bar H2 条件下，以水：异丙醇（1:1 v/v）混合物为溶剂，木糖初始浓度为 0.2 mmol/mL，木糖转化率为 98%，对木糖醇的选择性为 97%。此外，还与单独用水作为溶剂进行了比较。对反应进行了动力学研究。使用这种新型催化剂将木糖转化为木糖醇是一种绿色工艺，因为与传统的雷尼镍催化剂相比，这种催化剂的金属负载量要低得多，而且不需要使用铂、钯、铑或钌等贵金属，也没有金属浸出的问题，因此比目前报道的催化剂更为优越。
{"title":"Sustainable hydrogenation of xylose to xylitol using nickel-alumina catalysts supported on hexagonal mesoporous silica in water vis-à-vis aqueous isopropanol as solvent","authors":"Sneha R. Shetty , Ganapati D. Yadav","doi":"10.1016/j.cattod.2024.115105","DOIUrl":"10.1016/j.cattod.2024.115105","url":null,"abstract":"<div><div>Hydrogenation of xylose to xylitol is commercially attractive. The use of water as well as aqueous isopropanol as solvent using a novel robust catalyst was targeted in this work. This work showed that a nickel-alumina catalyst supported on hexagonal mesoporous silica (HMS) can effectively transform lignocellulose-derived xylose fraction to the value-added product, xylitol. HMS support was modified by simultaneous impregnating nickel (6 wt%) and alumina (4 wt%) which was subsequently oxidized. The catalyst was evaluated for its hydrogenation ability of xylose to xylitol. Identical reactions were carried out with HMS, alumina, Al/HMS and Ni/HMS to ascertain the activity of each moiety in the reaction. Before the reaction, the catalyst was reduced in a tubular reactor in the presence of hydrogen. Reaction parameters such as speed of agitation, type of precursor, metal loading, catalyst loading, solvent, concentration and temperature were studied and optimized. At 130℃ and 20 bar H<sub>2</sub>, initial xylose concentration of 0.2 mmol/mL with water: isopropanol (1:1 v/v) mixture as solvent, conversion of xylose was found to be 98 % with a selectivity of 97 % towards xylitol. Comparison was also made with water alone as a solvent. A kinetic study of the reaction was performed. The transformation of xylose to xylitol using this novel catalyst is a green process since it entails substantially lower metal loading when compared to the conventional Raney nickel catalysts, it does not involve the use of noble metals such as Pt, Pd, Rh or Ru, and also does not suffer from the problem of metal leaching, making it superior to those catalysts reported yet.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115105"},"PeriodicalIF":5.2,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-02DOI: 10.1016/j.cattod.2024.114556
John R. Regalbuto , Edward Chandler , Chigozie Ezeorah , Alaba Ojo , Nathan Thornburg , Mikayla Romero , Hien Pham , Abhaya Datye , Tae-Yeol Jeon , B. Frank Gupton , Christopher T. Williams
Strong Electrostatic Adsorption is a simple method to prepare highly dispersed supported metals. However, the minimum size of nanoparticles produced with gas phase reductions after SEA is typically about 1–2 nm. Alternative methods are explored to further decrease particle size, that is, to control the agglomeration of adsorbed precursors into nanoparticles, clusters, or isolated atoms. Three alternative methods have been employed to synthesize carbon supported Pt with higher dispersion than can be prepared by a “standard” method of strong electrostatic adsorption of charged Pt precursors followed by gas phase hydrogen reductions. First, gas phase reduction is replaced by a liquid phase reduction with hydrazine. Second, carbon black surfaces are oxidized to render them more hydrophilic and decrease the degree of agglomeration of Pt precursors after drying. The third method involves a switch of solvent from water to a solvent -acetone - which wets the carbon surface. The ensuing samples comprised of isolated atoms, clusters, and nanoparticles were characterized by high sensitivity XRD and z-contrast STEM imaging.
{"title":"From deposited metal precursors to supported atoms or nanoparticles","authors":"John R. Regalbuto , Edward Chandler , Chigozie Ezeorah , Alaba Ojo , Nathan Thornburg , Mikayla Romero , Hien Pham , Abhaya Datye , Tae-Yeol Jeon , B. Frank Gupton , Christopher T. Williams","doi":"10.1016/j.cattod.2024.114556","DOIUrl":"10.1016/j.cattod.2024.114556","url":null,"abstract":"<div><p>Strong Electrostatic Adsorption is a simple method to prepare highly dispersed supported metals. However, the minimum size of nanoparticles produced with gas phase reductions after SEA is typically about 1–2 nm. Alternative methods are explored to further decrease particle size, that is, to control the agglomeration of adsorbed precursors into nanoparticles, clusters, or isolated atoms. Three alternative methods have been employed to synthesize carbon supported Pt with higher dispersion than can be prepared by a “standard” method of strong electrostatic adsorption of charged Pt precursors followed by gas phase hydrogen reductions. First, gas phase reduction is replaced by a liquid phase reduction with hydrazine. Second, carbon black surfaces are oxidized to render them more hydrophilic and decrease the degree of agglomeration of Pt precursors after drying. The third method involves a switch of solvent from water to a solvent -acetone - which wets the carbon surface. The ensuing samples comprised of isolated atoms, clusters, and nanoparticles were characterized by high sensitivity XRD and z-contrast STEM imaging.</p></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"431 ","pages":"Article 114556"},"PeriodicalIF":5.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139666808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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