Pub Date : 2025-04-21DOI: 10.1016/j.cattod.2025.115344
Yukai Jiang, Bo Feng, Yingxiu Gao, Xiaohui Liu, Yanqin Wang
Polyamide 6 (PA6) is a kind of engineering plastic containing N atoms, the low activity of amide linkage makes it hard to recycle under mild conditions. In this work, a solid acid catalyst, L-Nb2O5 is applied to convert PA6 into ε-caprolactam and as high as 82.2 % yield was achieved at 260°C, a relatively low temperature with THF as solvent. The catalyst can be used for 5 times with little decline of catalytic activity, and can be regenerated through calcination. Catalytic mechanism investigation reveals that Lewis acidity rather than acid concentration plays a decisive role in depolymerization, whereas Brönsted acid sites exhibit an inhibitory effect on the process. Enhanced specific surface area facilitates the exposure of more acidic sites, thereby promoting depolymerization efficiency. Systematic cyclic stability assessments and scaled-up experiments confirm the system's robustness and practical viability for industrial implementation. This study ultimately establishes a facile and efficient methodology for achieving closed-loop recycling of polyamide 6 (PA6) to ε-caprolactam (CPL) through rational catalyst design.
{"title":"Efficient recycling of polyamide 6 to ε-caprolactam under mild conditions","authors":"Yukai Jiang, Bo Feng, Yingxiu Gao, Xiaohui Liu, Yanqin Wang","doi":"10.1016/j.cattod.2025.115344","DOIUrl":"10.1016/j.cattod.2025.115344","url":null,"abstract":"<div><div>Polyamide 6 (PA6) is a kind of engineering plastic containing N atoms, the low activity of amide linkage makes it hard to recycle under mild conditions. In this work, a solid acid catalyst, L-Nb<sub>2</sub>O<sub>5</sub> is applied to convert PA6 into ε-caprolactam and as high as 82.2 % yield was achieved at 260°C, a relatively low temperature with THF as solvent. The catalyst can be used for 5 times with little decline of catalytic activity, and can be regenerated through calcination. Catalytic mechanism investigation reveals that Lewis acidity rather than acid concentration plays a decisive role in depolymerization, whereas Brönsted acid sites exhibit an inhibitory effect on the process. Enhanced specific surface area facilitates the exposure of more acidic sites, thereby promoting depolymerization efficiency. Systematic cyclic stability assessments and scaled-up experiments confirm the system's robustness and practical viability for industrial implementation. This study ultimately establishes a facile and efficient methodology for achieving closed-loop recycling of polyamide 6 (PA6) to ε-caprolactam (CPL) through rational catalyst design.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"456 ","pages":"Article 115344"},"PeriodicalIF":5.2,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860429","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 : 2025-04-17DOI: 10.1016/j.cattod.2025.115342
Hubert Ronduda , Małgorzata Lemańska , Urszula Ulkowska , Wojciech Patkowski , Andrzej Ostrowski , Kamil Sobczak , Wioletta Raróg-Pilecka
A series of BaCeO3 doped with various rare-earth elements (REE = Nd, Sm, Gd) were synthesised and used as the supports for cobalt catalysts for ammonia synthesis. The effects of rare-earth dopant type and concentration on the physicochemical properties and catalytic activities were studied using, e.g., XRD, STEM-EDX, and TPD techniques. Catalyst testing revealed that the optimal doping concentration was 10 mol%, regardless of the rare-earth ion. Samarium was identified as the most effective dopant, followed by gadolinium and neodymium. The superior performance of the Co/BaCe0.9REE0.1O3–δ catalysts was due to the incorporation of REE dopant into the BaCeO3 structure, which increased the electron density, enabling efficient electron transfer from the support to the Co surface. This, in turn, facilitated the N2 dissociative adsorption, recognised as the rate-determining step (RDS) of ammonia synthesis. In addition, the catalysts were characterised by favourable hydrogen adsorption properties (co-existence of weak and strong adsorption sites), contributing to the effective hydrogen activation under the reaction conditions. This study provides an effective approach for designing cobalt catalysts supported on perovskites, demonstrating their great potential as next-generation catalysts for ammonia synthesis.
{"title":"Enhanced ammonia synthesis over barium cerate-supported cobalt catalyst by rare-earth element doping","authors":"Hubert Ronduda , Małgorzata Lemańska , Urszula Ulkowska , Wojciech Patkowski , Andrzej Ostrowski , Kamil Sobczak , Wioletta Raróg-Pilecka","doi":"10.1016/j.cattod.2025.115342","DOIUrl":"10.1016/j.cattod.2025.115342","url":null,"abstract":"<div><div>A series of BaCeO<sub>3</sub> doped with various rare-earth elements (REE = Nd, Sm, Gd) were synthesised and used as the supports for cobalt catalysts for ammonia synthesis. The effects of rare-earth dopant type and concentration on the physicochemical properties and catalytic activities were studied using, e.g., XRD, STEM-EDX, and TPD techniques. Catalyst testing revealed that the optimal doping concentration was 10 mol%, regardless of the rare-earth ion. Samarium was identified as the most effective dopant, followed by gadolinium and neodymium. The superior performance of the Co/BaCe<sub>0.9</sub>REE<sub>0.1</sub>O<sub>3–</sub><sub>δ</sub> catalysts was due to the incorporation of REE dopant into the BaCeO<sub>3</sub> structure, which increased the electron density, enabling efficient electron transfer from the support to the Co surface. This, in turn, facilitated the N<sub>2</sub> dissociative adsorption, recognised as the rate-determining step (RDS) of ammonia synthesis. In addition, the catalysts were characterised by favourable hydrogen adsorption properties (co-existence of weak and strong adsorption sites), contributing to the effective hydrogen activation under the reaction conditions. This study provides an effective approach for designing cobalt catalysts supported on perovskites, demonstrating their great potential as next-generation catalysts for ammonia synthesis.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"456 ","pages":"Article 115342"},"PeriodicalIF":5.2,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851536","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 : 2025-04-17DOI: 10.1016/j.cattod.2025.115340
Raúl Murciano, M. Teresa Navarro, Agustín Martínez
The one-pass conversion of renewable syngas into aromatics, particularly to BTX (benzene, toluene, xylenes) and para-xylene (PX), represents a promising approach to produce high-value sustainable chemicals from non-fossil resources. In this work, a systematic study of the modification of HZSM-5 zeolite by surface silylation and incorporation of MgO was performed aiming at maximising the BTX and PX selectivity in the syngas-to-aromatics (STA) reaction using tandem Zn-ZrO2+HZSM-5 catalysts following the methanol route. A zeolite with unusually large crystal size was purposedly used to intensify the shape selectivity effect. This zeolite exhibited high BTX selectivity (53.0 % in aromatics) albeit poor stability with TOS. Generation of a proper amount of mesopores via controlled desilication improved the catalyst stability and the aromatics selectivity (from 59.2 % up to 73.2 %) at the cost of lowering the BTX selectivity. Effective passivation of the external Brønsted acid sites was reached by submitting the mesoporous zeolite to four silylation cycles with TEOS. The silylation treatment significantly raised the BTX selectivity to 52.1 % while maintaining high selectivity of total aromatics (67.9 %), but had only a moderate positive effect on PX selectivity. Incorporation of Mg species in the silylated zeolite produced the largest impact on PX selectivity, attaining an outstanding value of 76.8 % in xylenes (41.2 % in aromatics) upon loading 3 wt% Mg.
{"title":"One-pass conversion of syngas to BTX/para-xylene aromatics over tandem oxide-zeolite catalysts based on large crystal size HZSM-5","authors":"Raúl Murciano, M. Teresa Navarro, Agustín Martínez","doi":"10.1016/j.cattod.2025.115340","DOIUrl":"10.1016/j.cattod.2025.115340","url":null,"abstract":"<div><div>The one-pass conversion of renewable syngas into aromatics, particularly to BTX (benzene, toluene, xylenes) and <em>para</em>-xylene (PX), represents a promising approach to produce high-value sustainable chemicals from non-fossil resources. In this work, a systematic study of the modification of HZSM-5 zeolite by surface silylation and incorporation of MgO was performed aiming at maximising the BTX and PX selectivity in the syngas-to-aromatics (STA) reaction using tandem Zn-ZrO<sub>2</sub>+HZSM-5 catalysts following the methanol route. A zeolite with unusually large crystal size was purposedly used to intensify the <em>shape selectivity</em> effect. This zeolite exhibited high BTX selectivity (53.0 % in aromatics) albeit poor stability with TOS. Generation of a proper amount of mesopores via controlled desilication improved the catalyst stability and the aromatics selectivity (from 59.2 % up to 73.2 %) at the cost of lowering the BTX selectivity. Effective passivation of the external Brønsted acid sites was reached by submitting the mesoporous zeolite to four silylation cycles with TEOS. The silylation treatment significantly raised the BTX selectivity to 52.1 % while maintaining high selectivity of total aromatics (67.9 %), but had only a moderate positive effect on PX selectivity. Incorporation of Mg species in the silylated zeolite produced the largest impact on PX selectivity, attaining an outstanding value of 76.8 % in xylenes (41.2 % in aromatics) upon loading 3 wt% Mg.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"456 ","pages":"Article 115340"},"PeriodicalIF":5.2,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860441","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 : 2025-04-14DOI: 10.1016/j.cattod.2025.115320
Álvaro Tolosana-Moranchel , Nicolas Bibent , José Luis Gómez de la Fuente , Moulay Tahar Sougrati , Frédéric Jaouen , Diego Gianolio , María Retuerto , Sergio Rojas
Fe/N/C based catalysts are the best positioned ones to replace the state-of-the-art Pt-based catalysts for the oxygen reduction reaction (ORR) in Proton Exchange Membrane Fuel Cells (PEMFCs). Here, a Fe/N/C catalyst characterized by a high N/C ratio, has been synthesized from the pyrolysis of a N-rich imine-based polymer. In acidic electrolyte (0.1 M HClO4) the catalyst demonstrates notable ORR activity with Eonset and E1/2 values of 1.09 and 0.77 V vs. RHE, respectively. Furthermore, the catalyst’s performance has been assessed in a single cell PEMFC setup. The optimization of the membrane electrode assembly (MEA) with the Fe/N/C catalyst entails examining various ionomer to catalyst ratios (I/C) as well as two coating methods: spray coating and drop casting. The optimized MEA achieved a cell performance of 725 mA cm−2 at 0.3 V and a power density close to 220 mW cm−2. In order to understand the factors influencing PEMFC polarisation curves, electrochemical impedance spectroscopy (EIS) was performed under potentiostatic conditions. The effect of operational parameters, such as ionomer to catalyst ratios (I/C) and the use of either O2 or air at the anode feed, has been investigated. EIS spectra allow the calculation of the distribution of relaxation times (DRT), providing insights into the rate and resistance of the ORR process occurring at the MEA. Notably, the cathode with an I/C= 2, prepared by drop casting, exhibited superior performance attributed to reduced ORR resistances. The current density and power density reached with the 25 cm2 MEA are comparable to those obtained with the 5 cm2 MEA using O2 as cathode reactant.
{"title":"Evaluation of the performance and detection of the oxygen reduction reaction kinetics of metal doped imine framework in proton exchange membrane fuel cells","authors":"Álvaro Tolosana-Moranchel , Nicolas Bibent , José Luis Gómez de la Fuente , Moulay Tahar Sougrati , Frédéric Jaouen , Diego Gianolio , María Retuerto , Sergio Rojas","doi":"10.1016/j.cattod.2025.115320","DOIUrl":"10.1016/j.cattod.2025.115320","url":null,"abstract":"<div><div>Fe/N/C based catalysts are the best positioned ones to replace the state-of-the-art Pt-based catalysts for the oxygen reduction reaction (ORR) in Proton Exchange Membrane Fuel Cells (PEMFCs). Here, a Fe/N/C catalyst characterized by a high N/C ratio, has been synthesized from the pyrolysis of a N-rich imine-based polymer. In acidic electrolyte (0.1 M HClO<sub>4</sub>) the catalyst demonstrates notable ORR activity with E<sub>onset</sub> and E<sub>1/2</sub> values of 1.09 and 0.77 V vs. RHE, respectively. Furthermore, the catalyst’s performance has been assessed in a single cell PEMFC setup. The optimization of the membrane electrode assembly (MEA) with the Fe/N/C catalyst entails examining various ionomer to catalyst ratios (I/C) as well as two coating methods: spray coating and drop casting. The optimized MEA achieved a cell performance of 725 mA cm<sup>−2</sup> at 0.3 V and a power density close to 220 mW cm<sup>−2</sup>. In order to understand the factors influencing PEMFC polarisation curves, electrochemical impedance spectroscopy (EIS) was performed under potentiostatic conditions. The effect of operational parameters, such as ionomer to catalyst ratios (I/C) and the use of either O<sub>2</sub> or air at the anode feed, has been investigated. EIS spectra allow the calculation of the distribution of relaxation times (DRT), providing insights into the rate and resistance of the ORR process occurring at the MEA. Notably, the cathode with an I/C= 2, prepared by drop casting, exhibited superior performance attributed to reduced ORR resistances. The current density and power density reached with the 25 cm<sup>2</sup> MEA are comparable to those obtained with the 5 cm<sup>2</sup> MEA using O<sub>2</sub> as cathode reactant.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"456 ","pages":"Article 115320"},"PeriodicalIF":5.2,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860440","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 : 2025-04-12DOI: 10.1016/j.cattod.2025.115315
Prabagar Jijoe Samuel , Challaraj Emmanuel E S , Vinod Divya , Mohammad Khalid , Mohammed H. Alqarni , Harikaranahalli Puttaiah Shivaraju
A simple methodology was devised for synthesizing the CaBi LDH/Ag-gC3N4 composite using eggshell-derived calcium. Composite is a potent catalyst for converting atmospheric gases into value-added derivatives and photocatalytic remediation with antimicrobial potential. An innovative CaBi LDH/Ag-gC3N4 was effectively fabricated using solvothermal and hydrothermal techniques and was subjected to sophisticated characterizations. Enhanced crystallinity with the intact framework of Ag-gC3N4 into CaBi LDH, agglomerated cloud-like structure, easy electron mobility transfer with extensive charge separation and high photocatalysis have been confirmed by characterization studies. The CaBi LDH/Ag-gC3N4 composite further demonstrated photocatalytic conversion of N2 and CO2 into NH3 (up to 84.02 µmol/L at 45 min) and functional hydrocarbon derivatives (C2H6O ∼350 μmol/L and CH3OH ∼118.2 μmol/L at 4 hr) respectively under visible light. The composite demonstrated superior photocatalytic remediation of ciprofloxacin (CPF) under visible spectrum and antibacterial efficacy against two pathogens, Escherichia coli and Staphylococcus aureus, supported by well suggested mechanism. The photoreduction mechanism of CaBi LDH/Ag-gC3N4 is discussed, and the CB position of g-C3N4 (-1.16 eV) showed comparatively having lesser value (negative) than CB of CaBi LDH (-0.73 eV). An intricate mechanism has been devised in each photocatalytic reaction to elucidate the general reactions in line with the intended reactions.
{"title":"Multifunctional CaBi LDH/Ag-gC3N4 catalytic composite for sustainable pollution remediation and photochemical conversion into usable derivatives","authors":"Prabagar Jijoe Samuel , Challaraj Emmanuel E S , Vinod Divya , Mohammad Khalid , Mohammed H. Alqarni , Harikaranahalli Puttaiah Shivaraju","doi":"10.1016/j.cattod.2025.115315","DOIUrl":"10.1016/j.cattod.2025.115315","url":null,"abstract":"<div><div>A simple methodology was devised for synthesizing the CaBi LDH/Ag-gC<sub>3</sub>N<sub>4</sub> composite using eggshell-derived calcium. Composite is a potent catalyst for converting atmospheric gases into value-added derivatives and photocatalytic remediation with antimicrobial potential. An innovative CaBi LDH/Ag-gC<sub>3</sub>N<sub>4</sub> was effectively fabricated using solvothermal and hydrothermal techniques and was subjected to sophisticated characterizations. Enhanced crystallinity with the intact framework of Ag-gC<sub>3</sub>N<sub>4</sub> into CaBi LDH, agglomerated cloud-like structure, easy electron mobility transfer with extensive charge separation and high photocatalysis have been confirmed by characterization studies. The CaBi LDH/Ag-gC<sub>3</sub>N<sub>4</sub> composite further demonstrated photocatalytic conversion of N<sub>2</sub> and CO<sub>2</sub> into NH<sub>3</sub> (up to 84.02 µmol/L at 45 min) and functional hydrocarbon derivatives (C<sub>2</sub>H<sub>6</sub>O ∼350 μmol/L and CH<sub>3</sub>OH ∼118.2 μmol/L at 4 hr) respectively under visible light. The composite demonstrated superior photocatalytic remediation of ciprofloxacin (CPF) under visible spectrum and antibacterial efficacy against two pathogens, <em>Escherichia coli and Staphylococcus aureus</em>, supported by well suggested mechanism. The photoreduction mechanism of CaBi LDH/Ag-gC<sub>3</sub>N<sub>4</sub> is discussed, and the CB position of g-C<sub>3</sub>N<sub>4</sub> (-1.16 eV) showed comparatively having lesser value (negative) than CB of CaBi LDH (-0.73 eV). An intricate mechanism has been devised in each photocatalytic reaction to elucidate the general reactions in line with the intended reactions.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"455 ","pages":"Article 115315"},"PeriodicalIF":5.2,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835374","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 : 2025-04-11DOI: 10.1016/j.cattod.2025.115318
D. Ballesteros-Plata , I. Barroso-Martín , J.A. Cecilia , P. Concepción , J.M. López Nieto , E. Rodríguez-Castellón , A. Infantes-Molina
A set of catalysts containing Cr- or Ga-doped Pt-CeO2 supported on alumina (PCA, Cr-PCA and Ga-PCA) were synthesized by incipient wetness impregnation and tested in propane conversion processes. The catalysts were studied in the propane conversion process with or without CO2 in the feed. In all cases, an enhancement in stability was found when CO2 was present in the reaction medium despite the lower catalytic activity. As well, all catalysts presented a higher propylene selectivity in the absence of CO2, indicating that the direct dehydrogenation of propane is the main reaction route. Moreover, CO2-assisted propane cracking to ethylene is favoured over propane reforming or direct cracking, given the minimal selectivity to other products like methane. With regards to the catalyst composition, Cr-PCA catalyst was the most active catalyst both in the absence and presence of CO2, due to the presence of weak acidity and coexistence of Cr3 + and Cr6+ redox species, as evidenced by XPS analysis. Ga-PCA catalyst was more selective to propylene, indicating that higher acidity of weak-to-medium nature along with formation of low coordinated Ga3+ species is beneficial for the CO2-ODH process. Raman, DTG and XPS analyses after reaction with CO2 showed that the deactivation of the catalysts was mainly due to carbon deposits of amorphous and graphitic nature on the surface of the catalysts.
{"title":"Influence of CO2 presence on propane conversion routes over Cr- and Ga-doped PtCe/Al2O3 catalysts","authors":"D. Ballesteros-Plata , I. Barroso-Martín , J.A. Cecilia , P. Concepción , J.M. López Nieto , E. Rodríguez-Castellón , A. Infantes-Molina","doi":"10.1016/j.cattod.2025.115318","DOIUrl":"10.1016/j.cattod.2025.115318","url":null,"abstract":"<div><div>A set of catalysts containing Cr- or Ga-doped Pt-CeO<sub>2</sub> supported on alumina (PCA, Cr-PCA and Ga-PCA) were synthesized by incipient wetness impregnation and tested in propane conversion processes. The catalysts were studied in the propane conversion process with or without CO<sub>2</sub> in the feed. In all cases, an enhancement in stability was found when CO<sub>2</sub> was present in the reaction medium despite the lower catalytic activity. As well, all catalysts presented a higher propylene selectivity in the absence of CO<sub>2</sub>, indicating that the direct dehydrogenation of propane is the main reaction route. Moreover, CO<sub>2</sub>-assisted propane cracking to ethylene is favoured over propane reforming or direct cracking, given the minimal selectivity to other products like methane. With regards to the catalyst composition, Cr-PCA catalyst was the most active catalyst both in the absence and presence of CO<sub>2</sub>, due to the presence of weak acidity and coexistence of Cr<sup>3 +</sup> and Cr<sup>6+</sup> redox species, as evidenced by XPS analysis. Ga-PCA catalyst was more selective to propylene, indicating that higher acidity of weak-to-medium nature along with formation of low coordinated Ga<sup>3+</sup> species is beneficial for the CO<sub>2</sub>-ODH process. Raman, DTG and XPS analyses after reaction with CO<sub>2</sub> showed that the deactivation of the catalysts was mainly due to carbon deposits of amorphous and graphitic nature on the surface of the catalysts.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"455 ","pages":"Article 115318"},"PeriodicalIF":5.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835372","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 : 2025-04-11DOI: 10.1016/j.cattod.2025.115317
Gustavo do N. Franceschini , Patricia Concepcion , Marcio Schwaab , Joaquín Martínez-Triguero , José M. Lopez Nieto
The dehydrogenation of ethane in the presence of CO2 on alumina supported Fe-Ni-O catalysts was studied. The Fe/Ni ratio in catalysts strongly influences both the conversion of ethane and CO2 and the nature of reaction products. Iron species, linked to the hematite phase (α-Fe3O4), favors ethane ODH but also the RWGS and dry reforming reactions (as parallel reactions). Nickel oxide has a high catalytic activity due to its capacity to break both C-H and CC bonds in a non-selective way, facilitating the generation of CO. Characterization results show changes in catalysts during the reaction. The H2-TPR patterns of catalysts suggest a low interaction between the support and the iron particles, and a parallelism between the reducibility of iron particles and the conversion of reactants. In addition, all catalysts suffer important restructuration under reaction conditions, with iron oxide segregates to the catalyst surface together with a partial reduction of Fe3+ to Fe2+ (as determined by XPS). These changes could be confirmed by XRD, Raman, XPS and UV–vis spectroscopy analyses. Temperature programmed surface reactions (TPSR), under different experimental conditions, indicate an important role of nickel in the bimetallic catalysts, avoiding severe reduction of the catalyst and stabilizing different types of iron oxide species with different selectivity to products.
{"title":"Ethane ODH with CO2 over alumina-supported Fe-Ni-O mixed oxides catalysts","authors":"Gustavo do N. Franceschini , Patricia Concepcion , Marcio Schwaab , Joaquín Martínez-Triguero , José M. Lopez Nieto","doi":"10.1016/j.cattod.2025.115317","DOIUrl":"10.1016/j.cattod.2025.115317","url":null,"abstract":"<div><div>The dehydrogenation of ethane in the presence of CO<sub>2</sub> on alumina supported Fe-Ni-O catalysts was studied. The Fe/Ni ratio in catalysts strongly influences both the conversion of ethane and CO<sub>2</sub> and the nature of reaction products. Iron species, linked to the hematite phase (α-Fe<sub>3</sub>O<sub>4</sub>), favors ethane ODH but also the RWGS and dry reforming reactions (as parallel reactions). Nickel oxide has a high catalytic activity due to its capacity to break both C-H and C<img>C bonds in a non-selective way, facilitating the generation of CO. Characterization results show changes in catalysts during the reaction. The H<sub>2</sub>-TPR patterns of catalysts suggest a low interaction between the support and the iron particles, and a parallelism between the reducibility of iron particles and the conversion of reactants. In addition, all catalysts suffer important restructuration under reaction conditions, with iron oxide segregates to the catalyst surface together with a partial reduction of Fe<sup>3</sup><sup>+</sup> to Fe<sup>2+</sup> (as determined by XPS). These changes could be confirmed by XRD, Raman, XPS and UV–vis spectroscopy analyses. Temperature programmed surface reactions (TPSR), under different experimental conditions, indicate an important role of nickel in the bimetallic catalysts, avoiding severe reduction of the catalyst and stabilizing different types of iron oxide species with different selectivity to products.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"455 ","pages":"Article 115317"},"PeriodicalIF":5.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843702","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}
Renewable dimethyl ether (DME) can reduce the carbon footprint in LPG and transportation sectors. The direct synthesis of DME (DDMES) is attracting a great deal of attention because it is possible to increase the productivity of DME. However, DDMES is hindered by the formation of a high amount of water, which promotes the deactivation of both catalytic phases used in the DDMES, namely Cu/ZnO/Al2O3 and γ-Al2O3. This is particularly relevant when CO2-rich syngas is used, since it leads to a higher production of H2O. In this work we show that heteropolyacids such as HSiW are a suitable alternative to state-of-the-art γ-Al2O3 for the dehydration of methanol during the DDMES. This is because HSiW is not deactivated by the presence of water in the reaction medium. Thus, catalytic beds with HSiW reach up to four times higher DME productivity than those containing γ-Al2O3. This feature is further exacerbated when water is removed from the reactor by means of a sorbent, i.e., during the sorption enhanced direct DME synthesis (SEDMES). Thus, the total carbon conversion is higher for SEDMES than for DDMES regardless of the actual nature of the acid catalyst.
{"title":"Improved productivity in direct dimethyl ether synthesis and sorption enhanced DME synthesis using tungstosilicic acid as the acidic function","authors":"Cristina Peinado , Dalia Liuzzi , Jurriaan Boon , Sergio Rojas","doi":"10.1016/j.cattod.2025.115319","DOIUrl":"10.1016/j.cattod.2025.115319","url":null,"abstract":"<div><div>Renewable dimethyl ether (DME) can reduce the carbon footprint in LPG and transportation sectors. The direct synthesis of DME (DDMES) is attracting a great deal of attention because it is possible to increase the productivity of DME. However, DDMES is hindered by the formation of a high amount of water, which promotes the deactivation of both catalytic phases used in the DDMES, namely Cu/ZnO/Al<sub>2</sub>O<sub>3</sub> and γ-Al<sub>2</sub>O<sub>3</sub>. This is particularly relevant when CO<sub>2</sub>-rich syngas is used, since it leads to a higher production of H<sub>2</sub>O. In this work we show that heteropolyacids such as HSiW are a suitable alternative to state-of-the-art γ-Al<sub>2</sub>O<sub>3</sub> for the dehydration of methanol during the DDMES. This is because HSiW is not deactivated by the presence of water in the reaction medium. Thus, catalytic beds with HSiW reach up to four times higher DME productivity than those containing γ-Al<sub>2</sub>O<sub>3</sub>. This feature is further exacerbated when water is removed from the reactor by means of a sorbent, i.e., during the sorption enhanced direct DME synthesis (SEDMES). Thus, the total carbon conversion is higher for SEDMES than for DDMES regardless of the actual nature of the acid catalyst.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"455 ","pages":"Article 115319"},"PeriodicalIF":5.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829756","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 : 2025-04-11DOI: 10.1016/j.cattod.2025.115322
Sabrina B. Karakache, Maroua Rouabah, Ryan Gosselin, Nicolas Abatzoglou, Inès E. Achouri
This study aimed to investigate the use of hydroxyapatite (HAp) as a catalyst support for the methane steam reforming (MSR) process. Catalysts were prepared via incipient wetness impregnation using nickel as the active metal and characterized by N2 physisorption analysis, X-ray diffraction, H2 temperature-programmed reduction, and transmission electron microscopy. The effects of four key parameters in hydrogen production—nickel loading (Ni wt%), inlet steam-to-methane (H2O/CH4) ratio, space velocity (SV), and temperature (T)—were evaluated via a statistical analysis. Thermodynamic calculations were also used to compare the catalyst activity results with the equilibrium conditions. The findings confirmed the effectiveness and stability of HAp as a support, exhibiting high thermal stability, coke resistance, and a mesoporous structure with an average specific surface area of 65 m2·g−1. The calcined Ni/HAp catalyst mainly comprised crystalline NiO and displayed a higher surface area of 54 m2·g−1 and superior dispersion at loadings of 5 and 10 wt% Ni compared to 15 wt% Ni. The temperature, SV, and inlet reactant ratio significantly influenced the process. A long-term stability test carried out under optimal conditions over 98 h demonstrated the consistent activity and stability of the 10 wt%Ni/HAp catalyst, maintaining a high methane conversion of 99 % and yielding 90 % hydrogen, 80 % carbon monoxide, and 20 % carbon dioxide, with no observed carbon deposition on the catalyst surface.
{"title":"Experimental study and statistical analysis of hydrogen yield in methane steam reforming over a hydroxyapatite-supported nickel catalyst","authors":"Sabrina B. Karakache, Maroua Rouabah, Ryan Gosselin, Nicolas Abatzoglou, Inès E. Achouri","doi":"10.1016/j.cattod.2025.115322","DOIUrl":"10.1016/j.cattod.2025.115322","url":null,"abstract":"<div><div>This study aimed to investigate the use of hydroxyapatite (HAp) as a catalyst support for the methane steam reforming (MSR) process. Catalysts were prepared via incipient wetness impregnation using nickel as the active metal and characterized by N<sub>2</sub> physisorption analysis, X-ray diffraction, H<sub>2</sub> temperature-programmed reduction, and transmission electron microscopy. The effects of four key parameters in hydrogen production—nickel loading (Ni wt%), inlet steam-to-methane (H<sub>2</sub>O/CH<sub>4</sub>) ratio, space velocity (SV), and temperature (T)—were evaluated via a statistical analysis. Thermodynamic calculations were also used to compare the catalyst activity results with the equilibrium conditions. The findings confirmed the effectiveness and stability of HAp as a support, exhibiting high thermal stability, coke resistance, and a mesoporous structure with an average specific surface area of 65 m<sup>2</sup>·g<sup>−1</sup>. The calcined Ni/HAp catalyst mainly comprised crystalline NiO and displayed a higher surface area of 54 m<sup>2</sup>·g<sup>−1</sup> and superior dispersion at loadings of 5 and 10 wt% Ni compared to 15 wt% Ni. The temperature, SV, and inlet reactant ratio significantly influenced the process. A long-term stability test carried out under optimal conditions over 98 h demonstrated the consistent activity and stability of the 10 wt%Ni/HAp catalyst, maintaining a high methane conversion of 99 % and yielding 90 % hydrogen, 80 % carbon monoxide, and 20 % carbon dioxide, with no observed carbon deposition on the catalyst surface.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"456 ","pages":"Article 115322"},"PeriodicalIF":5.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847579","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 : 2025-04-11DOI: 10.1016/j.cattod.2025.115337
Donato Pinto , Atsushi Urakawa
Simple metal oxides exhibit noticeable catalytic activity in methane conversion reactions. However, their catalytic role in the selective activation of CH4 to more valuable products (CO, H2, olefins) is often masked by the highly oxidative reaction conditions and by complex catalyst formulations. Transient studies of the direct interaction of CH4 with simple catalytic systems, including rare-earth (La2O3, Nd2O3, Y2O3), alkali-earth (MgO) and reducible (TiO2), reveal peculiar selectivity for different monometallic oxides. Rare-earth metal oxides show high initial activity towards partial oxidation products (CO, H2), while MgO possesses unique selectivity towards coupling products (C2H6 and C2H4) with remarkable activity in dehydrogenation reactions. A continuous supply of lattice oxygen species for the selective oxidation of CH4 to CO is provided by TiO2, which can effectively prevent accumulation of C deposits. The results indicate the roles played by the metal oxide materials and provide a basis for rational design of catalysts and reaction conditions for the selective conversion of CH4.
{"title":"Specific selectivity of simple oxides towards CH4 activation","authors":"Donato Pinto , Atsushi Urakawa","doi":"10.1016/j.cattod.2025.115337","DOIUrl":"10.1016/j.cattod.2025.115337","url":null,"abstract":"<div><div>Simple metal oxides exhibit noticeable catalytic activity in methane conversion reactions. However, their catalytic role in the selective activation of CH<sub>4</sub> to more valuable products (CO, H<sub>2</sub>, olefins) is often masked by the highly oxidative reaction conditions and by complex catalyst formulations. Transient studies of the direct interaction of CH<sub>4</sub> with simple catalytic systems, including rare-earth (La<sub>2</sub>O<sub>3</sub>, Nd<sub>2</sub>O<sub>3</sub>, Y<sub>2</sub>O<sub>3</sub>), alkali-earth (MgO) and reducible (TiO<sub>2</sub>), reveal peculiar selectivity for different monometallic oxides. Rare-earth metal oxides show high initial activity towards partial oxidation products (CO, H<sub>2</sub>), while MgO possesses unique selectivity towards coupling products (C<sub>2</sub>H<sub>6</sub> and C<sub>2</sub>H<sub>4</sub>) with remarkable activity in dehydrogenation reactions. A continuous supply of lattice oxygen species for the selective oxidation of CH<sub>4</sub> to CO is provided by TiO<sub>2</sub>, which can effectively prevent accumulation of C deposits. The results indicate the roles played by the metal oxide materials and provide a basis for rational design of catalysts and reaction conditions for the selective conversion of CH<sub>4</sub>.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"455 ","pages":"Article 115337"},"PeriodicalIF":5.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838489","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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