Copper promoted with zinc is an active catalyst for carbon dioxide hydrogenation to methanol, a reaction relevant to carbon capture and utilization technologies. Previous work showed that inverse zinc-on-copper catalysts on zirconia supports, where zinc(II) is added via atomic layer deposition (ALD), are more active and selective in this reaction than copper-on-zinc catalysts on zirconia. This work continues exploring the inverse zinc-on-copper catalysts by varying the support, comparing zirconia support with alumina, titania and niobia, and with various combinations of the ceria-zirconia-lanthana mixed oxide family. Catalyst characterization was made with elemental analysis, temperature-programmed reduction, temperature-programmed desorption of carbon dioxide, nitrous oxide pulse titration, and transmission electron microscopy. Activity was measured in a fixed-bed flow reactor at 450–550 K. ALD of Zn(II) acetylacetonate gave a similar areal number density of ca. two zinc per square nanometer on all tested supports. Zinc promotion systematically increased the methanol production rate. Among the tested catalysts, the zinc-on-copper on zirconia support remained the most active, with other catalysts from the ceria-zirconia-lanthana mixed oxide family giving almost as good results.
{"title":"Atomic layer deposited zinc promoted copper catalysts for carbon dioxide hydrogenation to methanol: Influence of support","authors":"Aitor Arandia , Jorge A. Velasco , Ahmed Sajid , Jihong Yim , Hammad Shamshad , Hua Jiang , Ashish Chahal , Abhinash Kumar Singh , Christine Gonsalves , Reetta Karinen , Riikka L. Puurunen","doi":"10.1016/j.cattod.2025.115283","DOIUrl":"10.1016/j.cattod.2025.115283","url":null,"abstract":"<div><div>Copper promoted with zinc is an active catalyst for carbon dioxide hydrogenation to methanol, a reaction relevant to carbon capture and utilization technologies. Previous work showed that inverse zinc-on-copper catalysts on zirconia supports, where zinc(II) is added via atomic layer deposition (ALD), are more active and selective in this reaction than copper-on-zinc catalysts on zirconia. This work continues exploring the inverse zinc-on-copper catalysts by varying the support, comparing zirconia support with alumina, titania and niobia, and with various combinations of the ceria-zirconia-lanthana mixed oxide family. Catalyst characterization was made with elemental analysis, temperature-programmed reduction, temperature-programmed desorption of carbon dioxide, nitrous oxide pulse titration, and transmission electron microscopy. Activity was measured in a fixed-bed flow reactor at 450–550 K. ALD of Zn(II) acetylacetonate gave a similar areal number density of ca. two zinc per square nanometer on all tested supports. Zinc promotion systematically increased the methanol production rate. Among the tested catalysts, the zinc-on-copper on zirconia support remained the most active, with other catalysts from the ceria-zirconia-lanthana mixed oxide family giving almost as good results.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"454 ","pages":"Article 115283"},"PeriodicalIF":5.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697760","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 : 2025-03-19DOI: 10.1016/j.cattod.2025.115285
Yu Shao , Yi Ding , Feng Jiao , Dengyun Miao , Shujing Guo , Junfeng Wang , Xiulian Pan
The aromatization of mixed C4 olefins is an important way to convert low value industrial C4 hydrocarbons by-products into value-added chemicals. Herein, we report CO2 facilitated aromatization of C4 olefins to benzene, toluene and xylene (BTX) using metal oxide-zeolite (OXZEO) bifunctional catalysts. An aromatics selectivity of 80.0 % at a CO2 conversion 10.5 % and butene conversion ∼100 % has been obtained at 500 °C and 1.0 MPa. The proportion of BTX in aromatics reaches as high as 91.0 %. Detailed characterization reveals that the Brønsted acid sites of ZSM-5 are the active sites for aromatization, while the presence of ZnCrAlOx oxides provides adsorption sites for CO2 and further reaction with the hydrogen species generated during aromatization. The presence of CO2 not only enhances the selectivity of aromatics, but also improves the stability of the reaction. 13C isotope experiments demonstrate that CO2 participates in the formation of aromatics. Furthermore, this new strategy is applicable for utilization of different sources of mixed C4 olefins and C4-C5 olefins, in addition to the benefits of utilizing CO2 towards a sustainable decarbonized society.
{"title":"CO2 facilitated aromatization of butenes to benzene, toluene and xylene","authors":"Yu Shao , Yi Ding , Feng Jiao , Dengyun Miao , Shujing Guo , Junfeng Wang , Xiulian Pan","doi":"10.1016/j.cattod.2025.115285","DOIUrl":"10.1016/j.cattod.2025.115285","url":null,"abstract":"<div><div>The aromatization of mixed C<sub>4</sub> olefins is an important way to convert low value industrial C<sub>4</sub> hydrocarbons by-products into value-added chemicals. Herein, we report CO<sub>2</sub> facilitated aromatization of C<sub>4</sub> olefins to benzene, toluene and xylene (BTX) using metal oxide-zeolite (OXZEO) bifunctional catalysts. An aromatics selectivity of 80.0 % at a CO<sub>2</sub> conversion 10.5 % and butene conversion ∼100 % has been obtained at 500 °C and 1.0 MPa. The proportion of BTX in aromatics reaches as high as 91.0 %. Detailed characterization reveals that the Brønsted acid sites of ZSM-5 are the active sites for aromatization, while the presence of ZnCrAlO<sub>x</sub> oxides provides adsorption sites for CO<sub>2</sub> and further reaction with the hydrogen species generated during aromatization. The presence of CO<sub>2</sub> not only enhances the selectivity of aromatics, but also improves the stability of the reaction. <sup>13</sup>C isotope experiments demonstrate that CO<sub>2</sub> participates in the formation of aromatics. Furthermore, this new strategy is applicable for utilization of different sources of mixed C<sub>4</sub> olefins and C<sub>4</sub>-C<sub>5</sub> olefins, in addition to the benefits of utilizing CO<sub>2</sub> towards a sustainable decarbonized society.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"454 ","pages":"Article 115285"},"PeriodicalIF":5.2,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143739807","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 : 2025-03-19DOI: 10.1016/j.cattod.2025.115282
Denzil Moodley , Jana Potgieter , Prabashini Moodley , Renier Crous , Pieter van Helden , Lia van Zyl , Randy Cunningham , Jean Gauché , Kobus Visagie , Thys Botha , Michael Claeys , Eric van Steen
The Fischer-Tropsch (FT) process yields high-quality hydrocarbon products, including hard waxes used in adhesives, polymer processing, cosmetics, and pharmaceutical applications. Sasol commercially produces these hard waxes using precipitated iron-based catalysts, which are cost-effective compared to cobalt catalysts. With proper chemical promotion, these iron catalysts can produce a high-alpha (C25–40 = 0.95) product slate, suitable for hard wax production. However, iron catalysts are characterised by short reactor lifetimes, waste generation during production, sensitivity to high water partial pressures, and high CO2 production. These issues can be mitigated by using cobalt slurry catalysts. However, cobalt’s limited responsiveness to chemical promotion poses a significant obstacle, making it challenging to achieve hard wax selectivity under the same conditions. This study aims to enhance hard wax selectivity by tuning the active sites of a supported cobalt catalyst for stable operation at high per pass conversion. During activation and FT synthesis, nanoparticulate cobalt mainly exists in two phases: hexagonal close-packed (HCP) and face-centred cubic (FCC). Theoretical simulations indicated that the HCP phase has superior activity due to a greater variety of site arrangements. A reduction-carbiding-reduction (RCR) technique was developed to prepare HCP-rich cobalt catalysts. The performance of HCP-rich and FCC-HCP mixed catalysts (the latter produced by standard H2 activation) were assessed via in-situ magnetometry and lab-scale FT testing. The catalyst preparation and activation methods were scaled up to a pilot level and tested in a 2-inch slurry bubble column to evaluate catalyst hard wax yield, and to generate samples for application testing.
{"title":"Tuning the active sites of supported cobalt Fischer-Tropsch catalysts to enhance efficiency for hard wax production","authors":"Denzil Moodley , Jana Potgieter , Prabashini Moodley , Renier Crous , Pieter van Helden , Lia van Zyl , Randy Cunningham , Jean Gauché , Kobus Visagie , Thys Botha , Michael Claeys , Eric van Steen","doi":"10.1016/j.cattod.2025.115282","DOIUrl":"10.1016/j.cattod.2025.115282","url":null,"abstract":"<div><div>The Fischer-Tropsch (FT) process yields high-quality hydrocarbon products, including hard waxes used in adhesives, polymer processing, cosmetics, and pharmaceutical applications. Sasol commercially produces these hard waxes using precipitated iron-based catalysts, which are cost-effective compared to cobalt catalysts. With proper chemical promotion, these iron catalysts can produce a high-alpha (C<sub>25–40</sub> = 0.95) product slate, suitable for hard wax production. However, iron catalysts are characterised by short reactor lifetimes, waste generation during production, sensitivity to high water partial pressures, and high CO<sub>2</sub> production. These issues can be mitigated by using cobalt slurry catalysts. However, cobalt’s limited responsiveness to chemical promotion poses a significant obstacle, making it challenging to achieve hard wax selectivity under the same conditions. This study aims to enhance hard wax selectivity by tuning the active sites of a supported cobalt catalyst for stable operation at high per pass conversion. During activation and FT synthesis, nanoparticulate cobalt mainly exists in two phases: hexagonal close-packed (HCP) and face-centred cubic (FCC). Theoretical simulations indicated that the HCP phase has superior activity due to a greater variety of site arrangements. A reduction-carbiding-reduction (RCR) technique was developed to prepare HCP-rich cobalt catalysts. The performance of HCP-rich and FCC-HCP mixed catalysts (the latter produced by standard H<sub>2</sub> activation) were assessed via <em>in-situ</em> magnetometry and lab-scale FT testing. The catalyst preparation and activation methods were scaled up to a pilot level and tested in a 2-inch slurry bubble column to evaluate catalyst hard wax yield, and to generate samples for application testing.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"454 ","pages":"Article 115282"},"PeriodicalIF":5.2,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143695940","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 : 2025-03-18DOI: 10.1016/j.cattod.2025.115280
Gabriela M. Bertoldo , Alcineia C. Oliveira , Gilberto D. Saraiva , Gardenia S. Pinheiro , Rossano Lang , Elisabete M. Assaf , Alessandra Lucredio , Daniel Ballesteros-Plata , Enrique Rodríguez-Castellón
This work aims to evaluate the influence of defective nanostructured alumina supports on the catalytic performance of the solids in the TRM reaction. The synergistic effects between NiPt nanoparticles on the nanostructured alumina support is also examined. Depending on the promoter added to the nanostructured alumina i.e., Zn, Mg or La, stable spinel phases or solid solutions with abundant intrinsic oxygen defects are formed. For NiPt/Al2ZnxOy and NiPt/Al2LaxOy, enriched PtOx and NiO nanoparticles microenvironments surrounding the defective support facilitate oxygen diffusion within the crystal lattice to the NiPt surface, which appeared to be the reason for the activity of the solids in the reaction. The NiPt/Al2MgxOy formed a NiO-MgO solid solution and out layer spinel phases, in which the presence of lattice oxygen species and extended defects helped by the accessible NiPt alloy on the support surface gave a strong metal-support interaction. This results in an improvement of the methane and CO2 conversions of 75 and 95 % at H2/CO ratio of 1.3.
{"title":"Effects of defective nanostructured alumina supports on the syngas production by tri-reforming of methane","authors":"Gabriela M. Bertoldo , Alcineia C. Oliveira , Gilberto D. Saraiva , Gardenia S. Pinheiro , Rossano Lang , Elisabete M. Assaf , Alessandra Lucredio , Daniel Ballesteros-Plata , Enrique Rodríguez-Castellón","doi":"10.1016/j.cattod.2025.115280","DOIUrl":"10.1016/j.cattod.2025.115280","url":null,"abstract":"<div><div>This work aims to evaluate the influence of defective nanostructured alumina supports on the catalytic performance of the solids in the TRM reaction. The synergistic effects between NiPt nanoparticles on the nanostructured alumina support is also examined. Depending on the promoter added to the nanostructured alumina <em>i.e.,</em> Zn, Mg or La, stable spinel phases or solid solutions with abundant intrinsic oxygen defects are formed. For NiPt/Al<sub>2</sub>Zn<sub>x</sub>O<sub>y</sub> and NiPt/Al<sub>2</sub>La<sub>x</sub>O<sub>y</sub>, enriched PtO<sub>x</sub> and NiO nanoparticles microenvironments surrounding the defective support facilitate oxygen diffusion within the crystal lattice to the NiPt surface, which appeared to be the reason for the activity of the solids in the reaction. The NiPt/Al<sub>2</sub>Mg<sub>x</sub>O<sub>y</sub> formed a NiO-MgO solid solution and out layer spinel phases, in which the presence of lattice oxygen species and extended defects helped by the accessible NiPt alloy on the support surface gave a strong metal-support interaction. This results in an improvement of the methane and CO<sub>2</sub> conversions of 75 and 95 % at H<sub>2</sub>/CO ratio of 1.3.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"454 ","pages":"Article 115280"},"PeriodicalIF":5.2,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685856","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}
The rapid emergence of viral infections, such as SARS-CoV-2, underscores the urgent need for innovative antiviral strategies. This study explores the photocatalytic effectiveness of synthesized mesoporous mTiO2-Ag nanostructures in denaturing viral proteins, thereby inhibiting viral spread. Utilizing protein models, specifically bovine serum albumin (BSA) and the spike protein subunit S1 (S1SP) of SARS-CoV-2, we evaluated the nanocomposite's ability to degrade high molecular weight proteins, simulating the interactions between photocatalysts and viral proteins. Our findings indicate that the mTiO2-Ag nanocomposite exhibits enhanced photocatalytic performance, effectively disrupting viral structures through reactive oxygen species (ROS) generation and physical interactions. This approach not only provides insights into the mechanisms of viral inactivation, pointing out the effect of photocatalytically generated ROS, as •OH, but also offers a safe alternative for assessing the antiviral properties of nanomaterials without the need for handling pathogenic viruses. The results support the potential application of photocatalytic nanomaterials in disinfection strategies, promoting safer and more effective solutions for controlling viral infections in various environments.
{"title":"TiO2-Ag nanostructured photocatalyst for viral inactivation: A preliminary study using protein models","authors":"Elisabetta Roberto , Ilaria De Pasquale , Massimo Dell’Edera , Nicoletta Depalo , Elisabetta Fanizza , Roberto Comparelli , Maria Lucia Curri","doi":"10.1016/j.cattod.2025.115278","DOIUrl":"10.1016/j.cattod.2025.115278","url":null,"abstract":"<div><div>The rapid emergence of viral infections, such as SARS-CoV-2, underscores the urgent need for innovative antiviral strategies. This study explores the photocatalytic effectiveness of synthesized mesoporous mTiO<sub>2</sub>-Ag nanostructures in denaturing viral proteins, thereby inhibiting viral spread. Utilizing protein models, specifically bovine serum albumin (BSA) and the spike protein subunit S1 (S1SP) of SARS-CoV-2, we evaluated the nanocomposite's ability to degrade high molecular weight proteins, simulating the interactions between photocatalysts and viral proteins. Our findings indicate that the mTiO<sub>2</sub>-Ag nanocomposite exhibits enhanced photocatalytic performance, effectively disrupting viral structures through reactive oxygen species (ROS) generation and physical interactions. This approach not only provides insights into the mechanisms of viral inactivation, pointing out the effect of photocatalytically generated ROS, as <sup>•</sup>OH, but also offers a safe alternative for assessing the antiviral properties of nanomaterials without the need for handling pathogenic viruses. The results support the potential application of photocatalytic nanomaterials in disinfection strategies, promoting safer and more effective solutions for controlling viral infections in various environments.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"454 ","pages":"Article 115278"},"PeriodicalIF":5.2,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697814","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 : 2025-03-13DOI: 10.1016/j.cattod.2025.115276
Ravindra Joshi , Manishkumar S. Tiwari
In keeping with principles of green chemistry, the alcoholysis of hemicellulose-derived furfuryl alcohol (FAL) into butyl levulinate (BL) by using magnetic deep eutectic solvents (MDES) as catalysts were studied. This research is significant as it contributes to developing sustainable and environmentally friendly processes in the chemical industry. Butyl levulinate is emerging as a valuable fuel additive, and its synthesis through the furfuryl alcohol route is faster, cheaper, and environmentally benign. Deep eutectic solvents (DES) that possess magnetic susceptibility are called magnetic deep eutectic solvents. In the current research, H-bond donors used to synthesize MDES were various carboxylic acids such as citric acid, oxalic acid, and p-toluenesulfonic acid monohydrate (p-TSAM). Choline chloride was used as H-bond acceptor. Ferric chloride was added to impart magnetism. Among the three catalysts, p-TSAM-based MDES was found to be the most efficient and subjected to further optimization studies. Reaction parameters (mole ratio of FAL to n-butanol, time of reaction, temperature of reaction, and concentration of catalyst) were varied to maximize yield, and optimum values were found. The highest BL yield was 98.42 % (393 K, 0.02 g/cm3 catalyst, molar ratio of FAL to n-butanol = 1:20, 600 rpm, 3 h). As the catalysts were magnetic, their isolation from the reaction mixture was unexacting. Catalyst recycling studies showed no appreciable loss of activity for four cycles.
{"title":"Upgradation of hemicellulose-derived furfuryl alcohol to butyl levulinate by using magnetic acidic deep eutectic solvents as catalysts","authors":"Ravindra Joshi , Manishkumar S. Tiwari","doi":"10.1016/j.cattod.2025.115276","DOIUrl":"10.1016/j.cattod.2025.115276","url":null,"abstract":"<div><div>In keeping with principles of green chemistry, the alcoholysis of hemicellulose-derived furfuryl alcohol (FAL) into butyl levulinate (BL) by using magnetic deep eutectic solvents (MDES) as catalysts were studied. This research is significant as it contributes to developing sustainable and environmentally friendly processes in the chemical industry. Butyl levulinate is emerging as a valuable fuel additive, and its synthesis through the furfuryl alcohol route is faster, cheaper, and environmentally benign. Deep eutectic solvents (DES) that possess magnetic susceptibility are called magnetic deep eutectic solvents. In the current research, H-bond donors used to synthesize MDES were various carboxylic acids such as citric acid, oxalic acid, and p-toluenesulfonic acid monohydrate (p-TSAM). Choline chloride was used as H-bond acceptor. Ferric chloride was added to impart magnetism. Among the three catalysts, p-TSAM-based MDES was found to be the most efficient and subjected to further optimization studies. Reaction parameters (mole ratio of FAL to n-butanol, time of reaction, temperature of reaction, and concentration of catalyst) were varied to maximize yield, and optimum values were found. The highest BL yield was 98.42 % (393 K, 0.02 g/cm<sup>3</sup> catalyst, molar ratio of FAL to n-butanol = 1:20, 600 rpm, 3 h). As the catalysts were magnetic, their isolation from the reaction mixture was unexacting. Catalyst recycling studies showed no appreciable loss of activity for four cycles.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"453 ","pages":"Article 115276"},"PeriodicalIF":5.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643048","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}
Iron catalysts supported on magnesium aluminate at different loadings were used in methane pyrolysis between 700 and 850 °C to evaluate the effect of particle size on the amount and properties of carbon nanotubes (CNT). All particles associated with CNTs were detached from the support, exhibiting a tip-growth mechanism. The lowest-loading catalysts with the average particle size of 6 nm produced the most carbon products with the lowest defect-to-graphite intensity ratios in Raman spectroscopy (0.13) when the reactor was at the lowest temperature. Higher temperatures led to iron particle sintering and lower carbon accumulation; at 850 °C, the thermal contribution to the total carbon mass was significant, catalyst particle encapsulation with graphite occurred and there was no CNT formation. There was no difference in the diameter of CNTs produced at different temperatures when the tubes were associated with the same Fe particle size, while reactions at the same temperature but different particle sizes produced CNTs of various diameters. The same correlation of CNT diameter with Fe particle size, rather than temperature, was observed in the characteristics of Raman spectra. This work provides evidence of the importance of particle size control and lower methane pyrolysis temperatures to enable enhanced production of CNT with higher quality.
{"title":"The effect of catalyst particle size and temperature on CNT growth on supported Fe catalysts during methane pyrolysis","authors":"Jing Shen , Jason Olfert , Ehsan Abbasi-Atibeh , Natalia Semagina","doi":"10.1016/j.cattod.2025.115275","DOIUrl":"10.1016/j.cattod.2025.115275","url":null,"abstract":"<div><div>Iron catalysts supported on magnesium aluminate at different loadings were used in methane pyrolysis between 700 and 850 °C to evaluate the effect of particle size on the amount and properties of carbon nanotubes (CNT). All particles associated with CNTs were detached from the support, exhibiting a tip-growth mechanism. The lowest-loading catalysts with the average particle size of 6 nm produced the most carbon products with the lowest defect-to-graphite intensity ratios in Raman spectroscopy (0.13) when the reactor was at the lowest temperature. Higher temperatures led to iron particle sintering and lower carbon accumulation; at 850 °C, the thermal contribution to the total carbon mass was significant, catalyst particle encapsulation with graphite occurred and there was no CNT formation. There was no difference in the diameter of CNTs produced at different temperatures when the tubes were associated with the same Fe particle size, while reactions at the same temperature but different particle sizes produced CNTs of various diameters. The same correlation of CNT diameter with Fe particle size, rather than temperature, was observed in the characteristics of Raman spectra. This work provides evidence of the importance of particle size control and lower methane pyrolysis temperatures to enable enhanced production of CNT with higher quality.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"453 ","pages":"Article 115275"},"PeriodicalIF":5.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643047","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 : 2025-03-12DOI: 10.1016/j.cattod.2025.115272
Débora Álvarez-Hernández, Svetlana Ivanova, Miguel Ángel Centeno
The catalytic oxidation of biomass-derived compounds represents a promising and sustainable pathway for the production of valuable chemicals, such as formic acid, which is a key candidate for hydrogen storage and CO₂-neutral energy applications. This study investigates the selective oxidation of glucose to formic acid using vanadium oxide supported on titania (VOx/TiO₂) as the catalytic system. This paper elucidates the reaction mechanism and analyzes the product distribution over time under controlled experimental conditions. The system exhibited selective glucose conversion, with formic acid emerging as the primary product, followed by intermediates such as arabinose, glyceraldehyde, acetic acid, and formaldehyde. Mechanistic studies suggested that the selective formation of formic acid proceeds via successive C1–C2 bond cleavage assisted by the peroxo species of vanadium. These findings highlight the key role of molecular and activated oxygen in the reaction pathway, while excluding the direct decomposition pathways for formic acid. This mechanistic insight and the role of vanadium-based peroxo species formed on the catalyst surface provide a critical foundation for optimizing catalyst design for biomass conversion processes.
{"title":"Mechanistic insights into the conversion of glucose to formic acid over vanadium-based catalyst","authors":"Débora Álvarez-Hernández, Svetlana Ivanova, Miguel Ángel Centeno","doi":"10.1016/j.cattod.2025.115272","DOIUrl":"10.1016/j.cattod.2025.115272","url":null,"abstract":"<div><div>The catalytic oxidation of biomass-derived compounds represents a promising and sustainable pathway for the production of valuable chemicals, such as formic acid, which is a key candidate for hydrogen storage and CO₂-neutral energy applications. This study investigates the selective oxidation of glucose to formic acid using vanadium oxide supported on titania (VOx/TiO₂) as the catalytic system. This paper elucidates the reaction mechanism and analyzes the product distribution over time under controlled experimental conditions. The system exhibited selective glucose conversion, with formic acid emerging as the primary product, followed by intermediates such as arabinose, glyceraldehyde, acetic acid, and formaldehyde. Mechanistic studies suggested that the selective formation of formic acid proceeds via successive C1–C2 bond cleavage assisted by the peroxo species of vanadium. These findings highlight the key role of molecular and activated oxygen in the reaction pathway, while excluding the direct decomposition pathways for formic acid. This mechanistic insight and the role of vanadium-based peroxo species formed on the catalyst surface provide a critical foundation for optimizing catalyst design for biomass conversion processes.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"453 ","pages":"Article 115272"},"PeriodicalIF":5.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682028","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 : 2025-03-12DOI: 10.1016/j.cattod.2025.115273
J. Chávez-Caiza , M. Navlani-García , J. Fernández-Catalá , Anand Bhardwaj , Cláudio M. Lousada , Lyubov M. Belova , Á. Berenguer-Murcia , D. Cazorla-Amorós
For the past decades, the scientific community has attempted to develop photocatalysts to obtain green hydrogen to diversify the current energy vectors, largely based on fossil fuels. In this context, many researchers have focused on modifying well-known photocatalysts such as TiO2 using other transition metals to boost photocatalytic activity in H2 production. However, powdered materials are difficult to reuse after prolonged exposure to liquid media in photocatalytic reactors. In this work, we have taken an alternative approach by developing structured catalysts based on TiO2 thin films and different Cu species. Photoluminescence analysis showed that incorporating Cu species on the TiO2 thin film decreases the e--h+ recombination rate. The photocatalytic activity of the nanostructured thin films is 298 µmol g−1 h−1 which is comparable to the reports described in the literature. Additionally, the thin films have simple and reproducible manufacturing, are easy to handle, are reusable and cost-effective. All these facts, make them a significantly more efficient technology than the counterpart powder materials.
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