Pub Date : 2024-10-03DOI: 10.1016/j.cattod.2024.115075
Ingeborg-Helene Svenum , Sylvain Gouttebroze , Francesca L. Bleken
In the Müller-Rochow process or direct process, CH3Cl reacts with silicon, forming (CH3)2SiCl2 (M2) as the dominant species with copper as catalyst. This complex and highly heterogeneous process takes place in a gas-solid stirred fluidized bed reactor. In this study, the formation of (CH3)2SiCl2 on a Cu rich Cu-Si model has been investigated using density functional theory (DFT). The results show that the overall reaction is exoergic. Upon dissociation of CH3Cl, the reaction proceeds first by interaction of CH3 with Si followed by subsequent addition of Cl. The largest activation barrier is found for the second Si-Cl bond formation in which a weakly adsorbed (CH3)2SiCl2 is formed. Compared to dehydrogenation of adsorbed CH3 formed upon dissociation of CH3Cl, formation of M2 is energetically favoured on a Si modified Cu(111) model.
{"title":"Formation of dimethyldichlorosilane (M2) in the Müller-Rochow process at the molecular level","authors":"Ingeborg-Helene Svenum , Sylvain Gouttebroze , Francesca L. Bleken","doi":"10.1016/j.cattod.2024.115075","DOIUrl":"10.1016/j.cattod.2024.115075","url":null,"abstract":"<div><div>In the Müller-Rochow process or direct process, CH<sub>3</sub>Cl reacts with silicon, forming (CH<sub>3</sub>)<sub>2</sub>SiCl<sub>2</sub> (M2) as the dominant species with copper as catalyst. This complex and highly heterogeneous process takes place in a gas-solid stirred fluidized bed reactor. In this study, the formation of (CH<sub>3</sub>)<sub>2</sub>SiCl<sub>2</sub> on a Cu rich Cu-Si model has been investigated using density functional theory (DFT). The results show that the overall reaction is exoergic. Upon dissociation of CH<sub>3</sub>Cl, the reaction proceeds first by interaction of CH<sub>3</sub> with Si followed by subsequent addition of Cl. The largest activation barrier is found for the second Si-Cl bond formation in which a weakly adsorbed (CH<sub>3</sub>)<sub>2</sub>SiCl<sub>2</sub> is formed. Compared to dehydrogenation of adsorbed CH<sub>3</sub> formed upon dissociation of CH<sub>3</sub>Cl, formation of M2 is energetically favoured on a Si modified Cu(111) model.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115075"},"PeriodicalIF":5.2,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418943","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 : 2024-10-02DOI: 10.1016/j.cattod.2024.115087
Aline Scaramuzza Aquino , Ismael dos Santos Belmonte , Cristiano Favero , Cristiane Xavier da Silva Campos , Anderson Joel Schwanke , Anne Gabriella Dias Santos , Michèle Oberson de Souza , Katia Bernardo Gusmão
The mitigation of environmental impacts caused by greenhouse gas emissions has become increasingly urgent, and the use of CO2 as a primary carbon source is an alternative in chemical transformations, including the synthesis of organic carbonates, formic acid, or methanol. This work aims to synthesize ionic liquids from the imidazolium cation family to be used in the cycloaddition of CO2 with ILs anchored in SiO2-clay heterostructure, MCM-41 and KIT-6 mesoporous materials, as well as the hydrogenation of CO2 with ILs added to ruthenium complexes, i.e., two catalytic systems. The most satisfactory result for CO2 cycloaddition (TON PC = 226) was obtained using the IL (MeO)3Sipmim.Cl anchored in SiO2-clay heterostructure (0.16 mol%) as the catalyst and ZnBr2 (0.04 mol%) as the co-catalyst. The hydrogenation was conducted with the IL (edaO)3Sipmim.Cl and the ruthenium complex Ru-PNN were not successful, but with co-catalyst PEHA, formic acid/formamide was produced (TON Form = 552). The unique catalytic system that showed activity for forming methanol was the commercial Ru-MACHO, Ru-C29H30ClNOP2, (TON MeOH = 3.3). These results highlight the potential of ruthenium-based complexes and supported ionic liquids as active systems in CO2 conversion.
减轻温室气体排放对环境的影响已变得日益紧迫，而使用二氧化碳作为主要碳源是化学转化（包括合成有机碳酸盐、甲酸或甲醇）的一种替代方法。这项工作旨在合成咪唑阳离子家族的离子液体，用于二氧化碳与锚定在二氧化硅-粘土异质结构、MCM-41 和 KIT-6 介孔材料中的离子液体的环加成反应，以及二氧化碳与添加到钌配合物中的离子液体的氢化反应，即两种催化体系。使用锚定在 SiO2-clay 异质结构中的 IL (MeO)3Sipmim.Cl （0.16 摩尔%）作为催化剂，ZnBr2（0.04 摩尔%）作为助催化剂，获得了最令人满意的 CO2 环加成结果（TON PC = 226）。使用 IL (edaO)3Sipmim.Cl 和钌络合物 Ru-PNN 进行氢化并不成功，但使用助催化剂 PEHA 则生成了甲酸/甲酰胺（TON Form = 552）。在生成甲醇方面显示出活性的独特催化体系是商用 Ru-MACHO，即 Ru-C29H30ClNOP2（TON MeOH = 3.3）。这些结果凸显了钌基配合物和支撑离子液体作为二氧化碳转化活性体系的潜力。
{"title":"Functionalization of ionic liquids for heterogeneous catalysis in CO2 conversion: Cycloaddition of epoxides and hydrogenation","authors":"Aline Scaramuzza Aquino , Ismael dos Santos Belmonte , Cristiano Favero , Cristiane Xavier da Silva Campos , Anderson Joel Schwanke , Anne Gabriella Dias Santos , Michèle Oberson de Souza , Katia Bernardo Gusmão","doi":"10.1016/j.cattod.2024.115087","DOIUrl":"10.1016/j.cattod.2024.115087","url":null,"abstract":"<div><div>The mitigation of environmental impacts caused by greenhouse gas emissions has become increasingly urgent, and the use of CO<sub>2</sub> as a primary carbon source is an alternative in chemical transformations, including the synthesis of organic carbonates, formic acid, or methanol. This work aims to synthesize ionic liquids from the imidazolium cation family to be used in the cycloaddition of CO<sub>2</sub> with ILs anchored in SiO<sub>2</sub>-clay heterostructure, MCM-41 and KIT-6 mesoporous materials, as well as the hydrogenation of CO<sub>2</sub> with ILs added to ruthenium complexes, i.e., two catalytic systems. The most satisfactory result for CO<sub>2</sub> cycloaddition (TON <sub>PC</sub> = 226) was obtained using the IL (MeO)<sub>3</sub>Sipmim.Cl anchored in SiO<sub>2</sub>-clay heterostructure (0.16 mol%) as the catalyst and ZnBr<sub>2</sub> (0.04 mol%) as the co-catalyst. The hydrogenation was conducted with the IL (edaO)<sub>3</sub>Sipmim.Cl and the ruthenium complex Ru-PNN were not successful, but with co-catalyst PEHA, formic acid/formamide was produced (TON <sub>Form</sub> = 552). The unique catalytic system that showed activity for forming methanol was the commercial Ru-MACHO, Ru-C<sub>29</sub>H<sub>30</sub>ClNOP<sub>2</sub>, (TON <sub>MeOH</sub> = 3.3). These results highlight the potential of ruthenium-based complexes and supported ionic liquids as active systems in CO<sub>2</sub> conversion.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115087"},"PeriodicalIF":5.2,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418949","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 : 2024-09-30DOI: 10.1016/j.cattod.2024.115086
Toyese Oyegoke , Achraf Sadier , Sara Navarro-Jaén , Alessia Ventimiglia , Nikolaos Dimitratos , Franck Dumeignil , Baba El-Yakubu Jibril , Robert Wojcieszak , Carine Michel
Lignocellulosic biomass holds promise for producing valuable chemicals. Among possible key reactions, the 5-hydroxymethylfurfural (HMF) oxidation to 2,5-furandicarboxylic acid (FDCA) using O2 as a final oxidant and supported Au catalysts is a promising route but that suffers from carbon balance issues. This study explores the mechanism of HMF oxidation to FDCA on a Au(111) model catalyst using computational modeling. Our results identify the main intermediate (HMFCA) and the major degradation pathways from HMF and HMFCA. Since we predict a higher degradation rate for HMF, we designed an experimental two-step approach, using a low temperature to convert fully HMF and improve the carbon balance and then raising the temperature to convert the HMFCA intermediate into FDCA. This approach was successful, reaching a high yield in FDCA (>90 %) in 8 hours while keeping the carbon balance above 97 %.
{"title":"Enhancing 5-hydroxymethylfurfural oxidation to 2,5-furan-dicarboxylic acid with Au-supported catalysts: Optimizing reaction parameters and unraveling degradation mechanism through DFT calculations","authors":"Toyese Oyegoke , Achraf Sadier , Sara Navarro-Jaén , Alessia Ventimiglia , Nikolaos Dimitratos , Franck Dumeignil , Baba El-Yakubu Jibril , Robert Wojcieszak , Carine Michel","doi":"10.1016/j.cattod.2024.115086","DOIUrl":"10.1016/j.cattod.2024.115086","url":null,"abstract":"<div><div>Lignocellulosic biomass holds promise for producing valuable chemicals. Among possible key reactions, the 5-hydroxymethylfurfural (HMF) oxidation to 2,5-furandicarboxylic acid (FDCA) using O<sub>2</sub> as a final oxidant and supported Au catalysts is a promising route but that suffers from carbon balance issues. This study explores the mechanism of HMF oxidation to FDCA on a Au(111) model catalyst using computational modeling. Our results identify the main intermediate (HMFCA) and the major degradation pathways from HMF and HMFCA. Since we predict a higher degradation rate for HMF, we designed an experimental two-step approach, using a low temperature to convert fully HMF and improve the carbon balance and then raising the temperature to convert the HMFCA intermediate into FDCA. This approach was successful, reaching a high yield in FDCA (>90 %) in 8 hours while keeping the carbon balance above 97 %.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115086"},"PeriodicalIF":5.2,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418946","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 : 2024-09-30DOI: 10.1016/j.cattod.2024.115079
Zhe-Hui Zhang , Ming-Jie Song , Saravanakumar Elangovan , Zhuohua Sun , Tong-Qi Yuan
Lignin is the largest renewable source of aromatic building blocks in nature and has great potential as a starting material for the production of bulk or functionalized aromatic compounds, providing a suitable alternative to widely used petroleum-derived chemicals. In this work, we present a novel 1,4-cyclohexanediol (CHDO) preparation from lignocellulose. In contrast to conventional methods, this pathway has taken the lignin-degrading monomers as a starting point, and flexibly employs a series of oxidative and catalytic reactions to achieve the preparation of CHDO. The proposed pathway consists of a two-step chemical process to efficiently obtain high yields of CHDO from lignocellulose. The first step is the oxidation of lignin-derived monophenols to p-hydroxyl phenolic compounds using the Dakin oxidation reaction (yield>80 %), and finally the de-functionalization and hydrogenation of the resulting monomers using the hydrodeoxygenation (HDO) reaction.
{"title":"From lignin-derived monomers to 1,4-cyclohexanediol via a two steps Dakin oxidation and hydrodeoxygenation reaction","authors":"Zhe-Hui Zhang , Ming-Jie Song , Saravanakumar Elangovan , Zhuohua Sun , Tong-Qi Yuan","doi":"10.1016/j.cattod.2024.115079","DOIUrl":"10.1016/j.cattod.2024.115079","url":null,"abstract":"<div><div>Lignin is the largest renewable source of aromatic building blocks in nature and has great potential as a starting material for the production of bulk or functionalized aromatic compounds, providing a suitable alternative to widely used petroleum-derived chemicals. In this work, we present a novel 1,4-cyclohexanediol (CHDO) preparation from lignocellulose. In contrast to conventional methods, this pathway has taken the lignin-degrading monomers as a starting point, and flexibly employs a series of oxidative and catalytic reactions to achieve the preparation of CHDO. The proposed pathway consists of a two-step chemical process to efficiently obtain high yields of CHDO from lignocellulose. The first step is the oxidation of lignin-derived monophenols to <em>p</em>-hydroxyl phenolic compounds using the Dakin oxidation reaction (yield>80 %), and finally the de-functionalization and hydrogenation of the resulting monomers using the hydrodeoxygenation (HDO) reaction.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115079"},"PeriodicalIF":5.2,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418948","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 : 2024-09-27DOI: 10.1016/j.cattod.2024.115077
Zhi-Gang Zhang , Shi-Kai Jiang , Xi Shen , Jia-Chun Lin , Yan Yi , Xiao-Jun Ji
Vanillin is an important flavoring compound commonly obtained through natural extraction or by chemical synthesis. However, the supply of naturally extracted vanillin is insufficient to meet the growing demand, and the utilization of chemically synthesized vanillin in various industries such as food and perfume is constrained due to growing health and environmental concerns. In light of this situation, biocatalysis offers promising perspectives to tackle these emerging challenges by employing either isolated enzymes or whole cells as biocatalysts. Recently, the biocatalytic synthesis of vanillin using biomass-derived compounds as precursors has been attracting increasing attention. This review aims to discuss recent advances in the synthesis of vanillin from various renewable biomass-based substrates through biocatalytic processes. A variety of recently discovered enzymes or recombinant cells used as biocatalysts for the production of vanillin are summarized. In addition, the protein engineering and the different strategies of constructing enzymatic cascade reactions applied to improve the bioconversion efficiency in vanillin production are also discussed.
{"title":"Biocatalytic synthesis of vanillin from biomass-derived compounds: A review","authors":"Zhi-Gang Zhang , Shi-Kai Jiang , Xi Shen , Jia-Chun Lin , Yan Yi , Xiao-Jun Ji","doi":"10.1016/j.cattod.2024.115077","DOIUrl":"10.1016/j.cattod.2024.115077","url":null,"abstract":"<div><div>Vanillin is an important flavoring compound commonly obtained through natural extraction or by chemical synthesis. However, the supply of naturally extracted vanillin is insufficient to meet the growing demand, and the utilization of chemically synthesized vanillin in various industries such as food and perfume is constrained due to growing health and environmental concerns. In light of this situation, biocatalysis offers promising perspectives to tackle these emerging challenges by employing either isolated enzymes or whole cells as biocatalysts. Recently, the biocatalytic synthesis of vanillin using biomass-derived compounds as precursors has been attracting increasing attention. This review aims to discuss recent advances in the synthesis of vanillin from various renewable biomass-based substrates through biocatalytic processes. A variety of recently discovered enzymes or recombinant cells used as biocatalysts for the production of vanillin are summarized. In addition, the protein engineering and the different strategies of constructing enzymatic cascade reactions applied to improve the bioconversion efficiency in vanillin production are also discussed.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115077"},"PeriodicalIF":5.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358618","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 : 2024-09-26DOI: 10.1016/j.cattod.2024.115074
Filip Zasada, Kim Steenbakers, Joanna Gryboś, Camillo Hudy, Zbigniew Sojka
Mechanistic investigations based on a combination of periodic-DFT+U and first principle thermodynamic modeling combined with IR and catalytic isotopic studies were used to ascertain the pathways of CO-PROX reaction over cobalt spinel nanocube catalyst. Structural, energetic, electronic, and magnetic characteristics of all surface intermediates (O2/O, H2, H2O, CO, CO2, CO3 adspecies) interacting single octahedral and tetrahedral (Cotet and Cooct) and double (Cotet‿Cooct and Cooct‿Cooct) active sites, was determined and their thermodynamic stabilities and mechanistic role were established. For the bare surface, CO and H2 oxidation were modeled based on an intrafacial Mars-van Krevelen mechanism, with the activation barriers of ΔEa = 1.21 for CO and 1.71 eV for H2. For the surface covered with different monoatomic oxygen species (Cotet2 C-O and Cooct5 C-O), various variants of the Eley-Rideal scheme of direct CO and H2 oxidation mechanisms were examined. These processes exhibit lower activation energies (ΔEa = 0.65 for CO and 1.11 eV for H2) than the intrafacial ones but are controlled by demanding prior dissociation of O2. The most stable in the CO-PROX conditions diatomic oxygen species give rise to the formation of Cotet-CO32--Cooct and Cooct-CO32--Cooct carbonate adspecies (with ΔEa = 0.42 and 0.35 eV, respectively), observed in IR. The Cotet-CO32--Cooct adduct being more stable acts as a spectator (CO2 release occurs with ΔEa = 1.21 eV), whereas the less stable Cooct-CO32--Cooct, as a key CO-PROX reaction intermediate (ΔEa of CO2 release equals to 0.81 eV). The prime role of the carbonate intermediates was substantiated by the isotopic experiments of the CO-PROX reaction over the Co3O4 nanocubes using 18O2 as an oxidant.
{"title":"DFT and experimental investigations into mechanistic aspects of CO-PROX reaction over Co3O4 nanocubes - activation of reactants and evaluation of the role of surface carbonate intermediates","authors":"Filip Zasada, Kim Steenbakers, Joanna Gryboś, Camillo Hudy, Zbigniew Sojka","doi":"10.1016/j.cattod.2024.115074","DOIUrl":"10.1016/j.cattod.2024.115074","url":null,"abstract":"<div><div>Mechanistic investigations based on a combination of periodic-DFT+U and first principle thermodynamic modeling combined with IR and catalytic isotopic studies were used to ascertain the pathways of CO-PROX reaction over cobalt spinel nanocube catalyst. Structural, energetic, electronic, and magnetic characteristics of all surface intermediates (O<sub>2</sub>/O, H<sub>2</sub>, H<sub>2</sub>O, CO, CO<sub>2</sub>, CO<sub>3</sub> adspecies) interacting single octahedral and tetrahedral (Co<sup>tet</sup> and Co<sup>oct</sup>) and double (Co<sup>tet</sup>‿Co<sup>oct</sup> and Co<sup>oct</sup>‿Co<sup>oct</sup>) active sites, was determined and their thermodynamic stabilities and mechanistic role were established. For the bare surface, CO and H<sub>2</sub> oxidation were modeled based on an intrafacial Mars-van Krevelen mechanism, with the activation barriers of Δ<em>E</em><sub>a</sub> = 1.21 for CO and 1.71 eV for H<sub>2</sub>. For the surface covered with different monoatomic oxygen species (Co<sup>tet</sup><sub>2 C</sub>-O and Co<sup>oct</sup><sub>5 C</sub>-O), various variants of the Eley-Rideal scheme of direct CO and H<sub>2</sub> oxidation mechanisms were examined. These processes exhibit lower activation energies (Δ<em>E</em><sub>a</sub> = 0.65 for CO and 1.11 eV for H<sub>2</sub>) than the intrafacial ones but are controlled by demanding prior dissociation of O<sub>2</sub>. The most stable in the CO-PROX conditions diatomic oxygen species give rise to the formation of Co<sup>tet</sup>-CO<sub>3</sub><sup>2-</sup>-Co<sup>oct</sup> and Co<sup>oct</sup>-CO<sub>3</sub><sup>2-</sup>-Co<sup>oct</sup> carbonate adspecies (with Δ<em>E</em><sub>a</sub> = 0.42 and 0.35 eV, respectively), observed in IR. The Co<sup>tet</sup>-CO<sub>3</sub><sup>2-</sup>-Co<sup>oct</sup> adduct being more stable acts as a spectator (CO<sub>2</sub> release occurs with Δ<em>E</em><sub>a</sub> = 1.21 eV), whereas the less stable Co<sup>oct</sup>-CO<sub>3</sub><sup>2-</sup>-Co<sup>oct</sup>, as a key CO-PROX reaction intermediate (Δ<em>E</em><sub>a</sub> of CO<sub>2</sub> release equals to 0.81 eV). The prime role of the carbonate intermediates was substantiated by the isotopic experiments of the CO-PROX reaction over the Co<sub>3</sub>O<sub>4</sub> nanocubes using <sup>18</sup>O<sub>2</sub> as an oxidant.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115074"},"PeriodicalIF":5.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327669","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 : 2024-09-26DOI: 10.1016/j.cattod.2024.115081
Yushuai Sang , Mingze Yang , Cedric Agyingi, Yongdan Li
Guaiacol ethanol alkylation (GEA), a model reaction of lignin solvolysis, has been intensively investigated. However, the product identification with gas chromatograph-mass spectrometer (GC-MS) was wrong due to the defect of the GC-MS databases. In this work, the main product was isolated with a flash chromatography technique and analyzed with 1H NMR and was identified as ethyl fully substituted phenol (or pentaethylphenol), which is contrary to the reported 2,6-di-tert-butyl-4-ethylphenol in previous literature. The NMR analysis of the entire product mixture further confirms that the product only contains ethyl substituted molecules, with no existence of isopropyl or tert-butyl substituted products. The byproducts, including ethyl partially substituted phenols, i.e., tetraethylphenol and triethylphenol, ethyl partially substituted guaiacol, 2-ethoxyphenol, and pentaethylbenzene, were also speculated based on the MS spectra. These findings rectify a long-standing error in product identification and may offer critical insights for mechanism investigations.
{"title":"Pentaethylphenol (Not 2,6-di-tert-butyl-4-ethylphenol) verified as the primary product of guaiacol ethanol alkylation reaction","authors":"Yushuai Sang , Mingze Yang , Cedric Agyingi, Yongdan Li","doi":"10.1016/j.cattod.2024.115081","DOIUrl":"10.1016/j.cattod.2024.115081","url":null,"abstract":"<div><div>Guaiacol ethanol alkylation (GEA), a model reaction of lignin solvolysis, has been intensively investigated. However, the product identification with gas chromatograph-mass spectrometer (GC-MS) was wrong due to the defect of the GC-MS databases. In this work, the main product was isolated with a flash chromatography technique and analyzed with <sup>1</sup>H NMR and was identified as ethyl fully substituted phenol (or pentaethylphenol), which is contrary to the reported 2,6-di-tert-butyl-4-ethylphenol in previous literature. The NMR analysis of the entire product mixture further confirms that the product only contains ethyl substituted molecules, with no existence of isopropyl or tert-butyl substituted products. The byproducts, including ethyl partially substituted phenols, i.e., tetraethylphenol and triethylphenol, ethyl partially substituted guaiacol, 2-ethoxyphenol, and pentaethylbenzene, were also speculated based on the MS spectra. These findings rectify a long-standing error in product identification and may offer critical insights for mechanism investigations.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115081"},"PeriodicalIF":5.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418945","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 : 2024-09-26DOI: 10.1016/j.cattod.2024.115055
Krateeka Madan, H. Seshagiri Rao, R.B. Harikrishna, G. Ranga Rao
In this work, hydrothermally synthesized SrTiO3 (STO) is subjected to ammonia reduction for 15 h and 45 h at 1000 ℃ under controlled conditions. The ammonia treatment reduced the band gap of SrTiO3 from 3.2 eV to 2.8 eV in ammonia-treated SrTiO3 samples (STON). XRD and Raman analysis confirm the presence of cubic phase in the STO and ammonia-treated STON-15 and STON-45 samples. Additionally, the presence of N due to ammonia reduction in STON-15 and STON-45 samples is verified by XPS analysis. In addition, XPS data shows an increase in the Ti3+ concentration in the STON-15 sample relative to the STON-45 sample when N is incorporated. STON-15 showed higher photocurrent density throughout the potential range of water splitting. An increase from 98 μA/cm2 to 250 μA/cm2 in the cathodic photocurrent density at 0 VRHE is obtained for STON-15 sample compared to STO sample. In contrast to STO, which only displayed a photocurrent density of 4.97 μA/cm2, STON-15 showed an anodic photocurrent density of 140 μA/cm2 at 1.23 VRHE. All the photoelectrochemical studies were carried out without using co-catalysts and sacrificial agents.
{"title":"N-doped Ti3+ rich SrTiO3 for efficient photoelectrochemical water splitting","authors":"Krateeka Madan, H. Seshagiri Rao, R.B. Harikrishna, G. Ranga Rao","doi":"10.1016/j.cattod.2024.115055","DOIUrl":"10.1016/j.cattod.2024.115055","url":null,"abstract":"<div><div>In this work, hydrothermally synthesized SrTiO<sub>3</sub> (STO) is subjected to ammonia reduction for 15 h and 45 h at 1000 ℃ under controlled conditions. The ammonia treatment reduced the band gap of SrTiO<sub>3</sub> from 3.2 eV to 2.8 eV in ammonia-treated SrTiO<sub>3</sub> samples (STON). XRD and Raman analysis confirm the presence of cubic phase in the STO and ammonia-treated STON-15 and STON-45 samples. Additionally, the presence of N due to ammonia reduction in STON-15 and STON-45 samples is verified by XPS analysis. In addition, XPS data shows an increase in the Ti<sup>3+</sup> concentration in the STON-15 sample relative to the STON-45 sample when N is incorporated. STON-15 showed higher photocurrent density throughout the potential range of water splitting. An increase from 98 μA/cm<sup>2</sup> to 250 μA/cm<sup>2</sup> in the cathodic photocurrent density at 0 V<sub>RHE</sub> is obtained for STON-15 sample compared to STO sample. In contrast to STO, which only displayed a photocurrent density of 4.97 μA/cm<sup>2</sup>, STON-15 showed an anodic photocurrent density of 140 μA/cm<sup>2</sup> at 1.23 V<sub>RHE</sub>. All the photoelectrochemical studies were carried out without using co-catalysts and sacrificial agents.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115055"},"PeriodicalIF":5.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418947","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 : 2024-09-26DOI: 10.1016/j.cattod.2024.115080
Yi Wang, Xiaolin Luo, Rui Lu, Fang Lu
Herein, a sustainable route to novel aromatic monomer, dimethyl 1,2,3,4-tetrahydro-1,4-methanonaphthalene-5,8-dicarboxylate, was developed, in which dimethyl muconate and norbornene used as the diene and dienophile undergo Diels-Alder reaction followed by dehydrogenation. The polycyclic cycloadduct, octahydro-1,4-methanonaphthalene-5,8-dicarboxylate, could be synthesized without catalyst. The activated carbon modified with sulfuric acid generated more oxygen-containing groups, stronger acidity and more acidic sites. Highly dispersed palladium metal particles with an average particle size of about 1.0 nm exhibited excellent activity in the dehydrogenation reaction and the yield of target product reached 73.8 %.
{"title":"Highly dispersed palladium supported on sulfuric acid-modified activated carbon for efficient dehydrogenation to produce novel aromatic monomer","authors":"Yi Wang, Xiaolin Luo, Rui Lu, Fang Lu","doi":"10.1016/j.cattod.2024.115080","DOIUrl":"10.1016/j.cattod.2024.115080","url":null,"abstract":"<div><div>Herein, a sustainable route to novel aromatic monomer, dimethyl 1,2,3,4-tetrahydro-1,4-methanonaphthalene-5,8-dicarboxylate, was developed, in which dimethyl muconate and norbornene used as the diene and dienophile undergo Diels-Alder reaction followed by dehydrogenation. The polycyclic cycloadduct, octahydro-1,4-methanonaphthalene-5,8-dicarboxylate, could be synthesized without catalyst. The activated carbon modified with sulfuric acid generated more oxygen-containing groups, stronger acidity and more acidic sites. Highly dispersed palladium metal particles with an average particle size of about 1.0 nm exhibited excellent activity in the dehydrogenation reaction and the yield of target product reached 73.8 %.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115080"},"PeriodicalIF":5.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323152","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 : 2024-09-26DOI: 10.1016/j.cattod.2024.115076
Hamza Bekkali, Guillaume Clet
In order to perform the characterization of liquid phase reactions catalysed by solid materials, several methodologies were developed using Raman spectroscopy. By following both the liquid and the solid-liquid interface, several layered materials could be discriminated. Indeed, molybdates or tungstates layered mixed oxides (with Nb or Ta oxides) show acidic properties that can catalyse several reactions including the conversion of polyalcohols. Therefore, these catalysts were extensively characterized not only initially to highlight their acidity and their capacity to favour molecular intercalation within their interlayers, but also to evaluate and monitor the catalysts under operando conditions. Layered molybdates, and HNbMoO6 in particular, proved to outperform the equivalent tungstates in hexanediol cyclodehydration, while tantalates were very similar to niobates. Our results show that while the moderate acidity of the molybdates is sufficient to perform this reaction, the overall catalytic activity is rather directly influenced by the accessibility of the reactant to the active sites in the interlayer.
{"title":"Discriminating molybdate and tungstate layered materials by operando Raman spectroscopy at the solid-liquid interface","authors":"Hamza Bekkali, Guillaume Clet","doi":"10.1016/j.cattod.2024.115076","DOIUrl":"10.1016/j.cattod.2024.115076","url":null,"abstract":"<div><div>In order to perform the characterization of liquid phase reactions catalysed by solid materials, several methodologies were developed using Raman spectroscopy. By following both the liquid and the solid-liquid interface, several layered materials could be discriminated. Indeed, molybdates or tungstates layered mixed oxides (with Nb or Ta oxides) show acidic properties that can catalyse several reactions including the conversion of polyalcohols. Therefore, these catalysts were extensively characterized not only initially to highlight their acidity and their capacity to favour molecular intercalation within their interlayers, but also to evaluate and monitor the catalysts under operando conditions. Layered molybdates, and HNbMoO<sub>6</sub> in particular, proved to outperform the equivalent tungstates in hexanediol cyclodehydration, while tantalates were very similar to niobates. Our results show that while the moderate acidity of the molybdates is sufficient to perform this reaction, the overall catalytic activity is rather directly influenced by the accessibility of the reactant to the active sites in the interlayer.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115076"},"PeriodicalIF":5.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358611","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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