Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical,...Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical, through oxidative esterification over Au-based catalysts. Detailed experimental studies showed that Au on amphoteric supports with appropriate strength and balanced ratio of acid and base sites can facilitate the desired oxidative-esterification pathway without accelerating undesired aldol-condensation or Cannizzaro reactions. In particular, hydroxyapatite (with a Ca/P ratio of 1.62) supported Au achieved 87% selectivity to methyl pyruvate at an acetol conversion of 62%.展开更多
Two dehydroabietic acid-based arylamines have been synthesized and characterized by FTIR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their spatial structures were determined by X-ray diffraction analysis. UV-...Two dehydroabietic acid-based arylamines have been synthesized and characterized by FTIR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their spatial structures were determined by X-ray diffraction analysis. UV-Vis absorption and fluorescence spectral characteristics of these compounds in methanol were investigated. Their fluorescence emission spectra in different polarity solvents were further evaluated. Fluorescent properties and structural relationship of the compounds showed that fluorescence intensity and quantum yield inversely increase with the non-coplanar degree. In addition, the solvent polarity has different effects on the fluorescence emission spectra of two compounds.展开更多
The electron donor properties of Pr6O11 activated at 300, 500 and 800℃ are reported from the studies on adsorption of electron acceptors of various electron affinity (7, 7, 8, 8-tetracyanoquinodimethane , 2. 3. 5. 6-...The electron donor properties of Pr6O11 activated at 300, 500 and 800℃ are reported from the studies on adsorption of electron acceptors of various electron affinity (7, 7, 8, 8-tetracyanoquinodimethane , 2. 3. 5. 6-tetrachloro-1, 4-benzoquin one, p-dinitrobenzene, and m-dinitrobenzcne) in three solvents (acetonitrile, 1,4-dioxan and ethyl acetate). The extent of electron transfer during adsorption is understood from magnetic measurements and ESR spectral data. The corresponding data on mixed oxides of Pr and Al are reported for various compositions. The acid / base properties of these oxides are determined using a set of Hammett indicators.展开更多
The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffra...The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffractometry(XRD).The study finds that the layer spacing of fluorine-free MXene is approximately twice that of MXene etched by the liquid-phase method,compared to the conventional liquidphase method.It also has greater capacitive properties.Therefore,the MXene prepared by this method shows a great potential for application in the field of capacitors.展开更多
In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selec...In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selectively modified the doping site structure,ultimately constructing a B,N co-doped frustrated Lewis acid-base pair catalyst.This catalyst exhibited remarkable catalytic activity,selectivity,and stability in the dehydrochlorination reaction of 1,1,2-trichloroethane(TCE).Detailed characterization and theoretical calculations revealed that the primary active center of this catalyst was the BN_(3)configuration.Compared to conventional graphitic N structures,the BN_(3)structure had a higher p-band center,ensuring superior adsorption and activation capabilities for TCE during the reaction.Within the BN_(3)site,three negatively charged nitrogen atoms acted as Lewis bases,while positively charged boron atoms acted as Lewis acids.This synergistic interaction facilitated the specific dissociation of chlorine and hydrogen atoms from TCE,significantly enhancing the 1,1-dichloroethene selectivity.Through this research,we not only explored the active site structure and catalytic mechanism of B,N co-doped catalysts in depth but also provided an efficient,selective,and stable catalyst for the dehydrochlorination of TCE,contributing significantly to the development of non-metallic catalysts.展开更多
Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herei...Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.展开更多
The influence of the textural and acidic properties ofγ‐Al2O3,(γ+χ)‐Al2O3,and?‐Al2O3on the catalytic activity,selectivity,and stability of direct H2S oxidation has been studied.A comparison of the H2S‐to‐S con...The influence of the textural and acidic properties ofγ‐Al2O3,(γ+χ)‐Al2O3,and?‐Al2O3on the catalytic activity,selectivity,and stability of direct H2S oxidation has been studied.A comparison of the H2S‐to‐S conversion effectiveness of aluminas with their acidic properties(identified by Fourier transform infrared spectroscopy and temperature programmed desorption of NH3)shows that H2S adsorption occurs predominantly on weak Lewis acid sites(LAS).γ‐Alumina samples containing aχ‐phase and/or modified Mg2+ions have a greater concentration of weak LAS and exhibit greater catalytic activity.When alumina is treated with a sulfuric acid solution,strong LAS appear and the number of LAS decreases significantly.Modification of alumina with hydrochloric acid has a limited effect on LAS strength.Weak LAS are retained and double in number compared to that present in the unmodified alumina,but the treated sample has Al?Cl bonds.Alumina samples modified by sulfate and chloride anions exhibit poor catalytic activity in H2S oxidation.展开更多
Surface Lewis acid-base sites in crystal structure may influence the physicochemical properties and the catalytic performances in nanozymes.Understanding the synergistic effect mechanism of Co_(3)O_(4)nanozymes toward...Surface Lewis acid-base sites in crystal structure may influence the physicochemical properties and the catalytic performances in nanozymes.Understanding the synergistic effect mechanism of Co_(3)O_(4)nanozymes towards substances(3,3’,5,5’-tetramethylbenzidine(TMB)and hydrogen peroxide(H2O2))induced by surface Lewis acid-base sites is important to enhance the efficiency for peroxidase-like reaction.Herein,ultrathin porous Co_(3)O_(4)nanosheets with abundant Lewis acid-base sites were prepared by sodium borohydride(NaBH4)reduction treatment,which exhibited high-efficiency peroxidase-like activity compared with original Co_(3)O_(4)nanosheets.The Lewis acid-base sites for ultrathin porous Co_(3)O_(4)nanosheets nanozyme were owing to the coordination unsaturation of Co ions and the formation of defect structure.Ultrathin porous Co_(3)O_(4)nanosheets had 18.26-fold higher catalytic efficiency(1.27×10^(-2)s^(-1)·mM^(-1))than that of original Co_(3)O_(4)(6.95×10^(-4)s^(-1)·mM^(-1))in oxidizing TMB substrate.The synergistic effect of surface acid and base sites can enhance the interfacial electron transfer process of Co_(3)O_(4)nanosheets,which can be a favor of absorption substrates and the generation of reactive intermediates such as radicals.Furthermore,the limit of detection of hydroquinol was 0.58μM for ultrathin porous Co_(3)O_(4)nanosheets,965-fold lower than original Co_(3)O_(4)(560μM).Besides,the linear range of ultrathin porous Co_(3)O_(4)nanosheets was widely with the concentration of 5.0-1,000μM.Colorimetric detection of hydroquinol by agarose-based hydrogel membrane was provided based on excellent peroxidase-like properties.This study provided insights into designing high-performance nanozymes for peroxidase-like catalysis via a strategy of solid surface acid-base sites engineering.展开更多
Ethanol is a considerable platform molecule in biomass conversion,which could be acquired in quantity through acetone-butanol-ethanol(ABE)fermentation.People have been working on the upgrading of ethanol to value adde...Ethanol is a considerable platform molecule in biomass conversion,which could be acquired in quantity through acetone-butanol-ethanol(ABE)fermentation.People have been working on the upgrading of ethanol to value added chemicals for decades.In the meantime,1-butanol and a series of value added products have been selectively generated through C–C bond coupling.In this mini-review,we focus on the recent advances in selective C–C bond formation over balanced Lewis acid-base catalysts such as modified metal oxide,mixed metal oxide,hydroxyapatite and zeolite confined transition metal oxide catalysts.Among them,Pd-MgAlO_x and Sr-based hydroxyapatite exhibit>70%1-butanol selectivity,while Zn——xZr_yO_z and Ta-Si BEA zeolite achieve>80%of isobutene and butadiene selectivity respectively.The mechanism and reaction pathway of C–C bond formation in each reaction system are described in detail.The correlation between C–C bond coupling and the acidity/basicity of the Lewis acid-base pairs from the surface of the catalysts are also discussed.展开更多
Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base ...Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base adducts via inkjet printing.Due to the unique weak coordination bond of B→N,it is feasible to construct anticounterfeiting information that is easy to erase.The in situ postsynthesis of the luminescent quick response codes via inkjet printing facilitates precision chemistry control to change the emission ranging from deep-blue(peaking at 407 nm)to orange-red(peaking at 597 nm).The encrypted information can be quickly erased either by modulating the temperature to dissociate the weak coordination or strong Lewis base to promote a neutralization reaction.展开更多
基金supported by the National Natural Science Foundation of China(91545114,91545203,and 21576227)the 985 Program of the Chemistry and Chemical Engineering disciplines of Xiamen University~~
文摘Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical, through oxidative esterification over Au-based catalysts. Detailed experimental studies showed that Au on amphoteric supports with appropriate strength and balanced ratio of acid and base sites can facilitate the desired oxidative-esterification pathway without accelerating undesired aldol-condensation or Cannizzaro reactions. In particular, hydroxyapatite (with a Ca/P ratio of 1.62) supported Au achieved 87% selectivity to methyl pyruvate at an acetol conversion of 62%.
基金supported by the National Natural Science Foundation of China (No. 31170539)
文摘Two dehydroabietic acid-based arylamines have been synthesized and characterized by FTIR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their spatial structures were determined by X-ray diffraction analysis. UV-Vis absorption and fluorescence spectral characteristics of these compounds in methanol were investigated. Their fluorescence emission spectra in different polarity solvents were further evaluated. Fluorescent properties and structural relationship of the compounds showed that fluorescence intensity and quantum yield inversely increase with the non-coplanar degree. In addition, the solvent polarity has different effects on the fluorescence emission spectra of two compounds.
文摘The electron donor properties of Pr6O11 activated at 300, 500 and 800℃ are reported from the studies on adsorption of electron acceptors of various electron affinity (7, 7, 8, 8-tetracyanoquinodimethane , 2. 3. 5. 6-tetrachloro-1, 4-benzoquin one, p-dinitrobenzene, and m-dinitrobenzcne) in three solvents (acetonitrile, 1,4-dioxan and ethyl acetate). The extent of electron transfer during adsorption is understood from magnetic measurements and ESR spectral data. The corresponding data on mixed oxides of Pr and Al are reported for various compositions. The acid / base properties of these oxides are determined using a set of Hammett indicators.
基金Funded by the National Natural Science Foundation of China Youth Program (51302073)the Green Light Materials Hubei Key Laboratory Open Fund (202027B11)。
文摘The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffractometry(XRD).The study finds that the layer spacing of fluorine-free MXene is approximately twice that of MXene etched by the liquid-phase method,compared to the conventional liquidphase method.It also has greater capacitive properties.Therefore,the MXene prepared by this method shows a great potential for application in the field of capacitors.
基金the funding support from the National Natural Science Foundation of China(Nos.22202036 and 22302001)the Jilin Province Scientific,the Technological Planning Project of China(No.20230101292JC).
文摘In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selectively modified the doping site structure,ultimately constructing a B,N co-doped frustrated Lewis acid-base pair catalyst.This catalyst exhibited remarkable catalytic activity,selectivity,and stability in the dehydrochlorination reaction of 1,1,2-trichloroethane(TCE).Detailed characterization and theoretical calculations revealed that the primary active center of this catalyst was the BN_(3)configuration.Compared to conventional graphitic N structures,the BN_(3)structure had a higher p-band center,ensuring superior adsorption and activation capabilities for TCE during the reaction.Within the BN_(3)site,three negatively charged nitrogen atoms acted as Lewis bases,while positively charged boron atoms acted as Lewis acids.This synergistic interaction facilitated the specific dissociation of chlorine and hydrogen atoms from TCE,significantly enhancing the 1,1-dichloroethene selectivity.Through this research,we not only explored the active site structure and catalytic mechanism of B,N co-doped catalysts in depth but also provided an efficient,selective,and stable catalyst for the dehydrochlorination of TCE,contributing significantly to the development of non-metallic catalysts.
基金supported by the National Natural Science Foundation of China (52161025)the Natural Science Foundation of Gansu Province (20JR10RA241)。
文摘Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.
基金This work was conducted within the framework of Program of the Russian Academy of Sciences and the Federal Agency for Scientific Organizations (state‐guaranteed order for BIC, Project АААА‐А17‐117041710086‐6).
文摘The influence of the textural and acidic properties ofγ‐Al2O3,(γ+χ)‐Al2O3,and?‐Al2O3on the catalytic activity,selectivity,and stability of direct H2S oxidation has been studied.A comparison of the H2S‐to‐S conversion effectiveness of aluminas with their acidic properties(identified by Fourier transform infrared spectroscopy and temperature programmed desorption of NH3)shows that H2S adsorption occurs predominantly on weak Lewis acid sites(LAS).γ‐Alumina samples containing aχ‐phase and/or modified Mg2+ions have a greater concentration of weak LAS and exhibit greater catalytic activity.When alumina is treated with a sulfuric acid solution,strong LAS appear and the number of LAS decreases significantly.Modification of alumina with hydrochloric acid has a limited effect on LAS strength.Weak LAS are retained and double in number compared to that present in the unmodified alumina,but the treated sample has Al?Cl bonds.Alumina samples modified by sulfate and chloride anions exhibit poor catalytic activity in H2S oxidation.
基金This work was supported by the National Natural Science Foundation of China(No.21876099)Shandong Provincial Natural Science Foundation(No.ZR2017PB007)Shandong Provincial Key Laboratory Project of Test Technology for Material Chemical Safety(No.2018SDCLHX005).
文摘Surface Lewis acid-base sites in crystal structure may influence the physicochemical properties and the catalytic performances in nanozymes.Understanding the synergistic effect mechanism of Co_(3)O_(4)nanozymes towards substances(3,3’,5,5’-tetramethylbenzidine(TMB)and hydrogen peroxide(H2O2))induced by surface Lewis acid-base sites is important to enhance the efficiency for peroxidase-like reaction.Herein,ultrathin porous Co_(3)O_(4)nanosheets with abundant Lewis acid-base sites were prepared by sodium borohydride(NaBH4)reduction treatment,which exhibited high-efficiency peroxidase-like activity compared with original Co_(3)O_(4)nanosheets.The Lewis acid-base sites for ultrathin porous Co_(3)O_(4)nanosheets nanozyme were owing to the coordination unsaturation of Co ions and the formation of defect structure.Ultrathin porous Co_(3)O_(4)nanosheets had 18.26-fold higher catalytic efficiency(1.27×10^(-2)s^(-1)·mM^(-1))than that of original Co_(3)O_(4)(6.95×10^(-4)s^(-1)·mM^(-1))in oxidizing TMB substrate.The synergistic effect of surface acid and base sites can enhance the interfacial electron transfer process of Co_(3)O_(4)nanosheets,which can be a favor of absorption substrates and the generation of reactive intermediates such as radicals.Furthermore,the limit of detection of hydroquinol was 0.58μM for ultrathin porous Co_(3)O_(4)nanosheets,965-fold lower than original Co_(3)O_(4)(560μM).Besides,the linear range of ultrathin porous Co_(3)O_(4)nanosheets was widely with the concentration of 5.0-1,000μM.Colorimetric detection of hydroquinol by agarose-based hydrogel membrane was provided based on excellent peroxidase-like properties.This study provided insights into designing high-performance nanozymes for peroxidase-like catalysis via a strategy of solid surface acid-base sites engineering.
基金supported by the “111 Project” of China (B18030) and Nankai University
文摘Ethanol is a considerable platform molecule in biomass conversion,which could be acquired in quantity through acetone-butanol-ethanol(ABE)fermentation.People have been working on the upgrading of ethanol to value added chemicals for decades.In the meantime,1-butanol and a series of value added products have been selectively generated through C–C bond coupling.In this mini-review,we focus on the recent advances in selective C–C bond formation over balanced Lewis acid-base catalysts such as modified metal oxide,mixed metal oxide,hydroxyapatite and zeolite confined transition metal oxide catalysts.Among them,Pd-MgAlO_x and Sr-based hydroxyapatite exhibit>70%1-butanol selectivity,while Zn——xZr_yO_z and Ta-Si BEA zeolite achieve>80%of isobutene and butadiene selectivity respectively.The mechanism and reaction pathway of C–C bond formation in each reaction system are described in detail.The correlation between C–C bond coupling and the acidity/basicity of the Lewis acid-base pairs from the surface of the catalysts are also discussed.
基金financially supported by the National Natural Science Foundation of China(No.62175189)the Program for Promoting Academic Collaboration and Senior Talent Fostering between China and Canada,Australia,New Zealand,and Latin America(2021-109)the joint China-Sweden Mobility programme(No.52211530052).
文摘Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base adducts via inkjet printing.Due to the unique weak coordination bond of B→N,it is feasible to construct anticounterfeiting information that is easy to erase.The in situ postsynthesis of the luminescent quick response codes via inkjet printing facilitates precision chemistry control to change the emission ranging from deep-blue(peaking at 407 nm)to orange-red(peaking at 597 nm).The encrypted information can be quickly erased either by modulating the temperature to dissociate the weak coordination or strong Lewis base to promote a neutralization reaction.
