Ethanol conversion to high-value-added products has attracted considerable attention in both academic research and industrial fields.In this study,we synthesized a series of tunable acid–base bifunctional Zn-Zr-Al me...Ethanol conversion to high-value-added products has attracted considerable attention in both academic research and industrial fields.In this study,we synthesized a series of tunable acid–base bifunctional Zn-Zr-Al metal oxides(represented as Zn2ZrxAl-MMO)in light of the structural topotactic transformation of Zn2ZrxAl-hydrotalcite precursors(Zn2ZrxAl-LDH).The resulting Zn2ZrxAl-MMO catalysts were employed in the conversion of ethanol to diethyl carbonate.The Zr^4+ ion content of the LDH precursor plays a key role in modulating the acid-base properties and determining catalytic performance:the Zn2Zr0.1Al-MMO sample exhibits the optimal catalytic behavior with a diethyl carbonate(DEC)yield of 42.1%,which is the highest reported for metal oxide catalysts.Structure-property correlation investigations revealed that the synergic catalysis between medium-strong basic sites and weak acid sites plays a predominant role in the catalytic behavior.Furthermore,in situ Fourier transform infrared measurements showed that the weak acidic site promotes activation adsorption of the reactant(urea)and the intermediate product(ethyl carbamate),while the medium-strong basic site accelerates ethanol activation.Moreover,the Zn2Zr0.1Al-MMO catalyst has the advantages of cost effectiveness,good stability,and reusability.Therefore,the acid-base bifunctional catalysts developed in this work can be employed as promising candidates in acid-base catalytic reactions such as ethanol conversion.展开更多
Developing non‐noble‐metal electrocatalyst with efficient and durable activity is a urgent task for addressing the sluggish reaction kinetics of electrochemical water oxidation.Structural evolution of the electrocat...Developing non‐noble‐metal electrocatalyst with efficient and durable activity is a urgent task for addressing the sluggish reaction kinetics of electrochemical water oxidation.Structural evolution of the electrocatalyst is an important strategy for achieving enhanced performance.Herein,in situ evolution of surface Co_(2)CrO_(4) to CoOOH/CrOOH(CoOOH/CrOOH‐Co_(2)CrO_(4))by an electrochemical method under alkaline conditions was designed for enhancing the electrocatalytic performance of water oxidation.The experiments demonstrated that the synergy between CoOOH/CrOOH and Co_(2)CrO_(4) resulted in a marked increase in the number of active sites and improved the rate of charge transfer,which enhanced the activity for water oxidation.At a geometrical current density of 20 mA cm^(−2),the overpotential of the oxygen evolution reaction was 244 mV and the turnover frequency was 0.536 s^(−1) in 1.0 M NaOH.展开更多
Using novel catalyst the pyrolysis of mixed plastics has been considered as an effective way to convert waste plastics into environmental friendly and industrially useful hydrocarbon gas and liquid products. Catalytic...Using novel catalyst the pyrolysis of mixed plastics has been considered as an effective way to convert waste plastics into environmental friendly and industrially useful hydrocarbon gas and liquid products. Catalytic cracking is a promising alternative for plastic wastes recycling. More than 99% of a polymer mixed converted into combustible hydrocarbon in a catalytic converting reaction. The products are mainly middle distillates. In this work equally weighted mixed HDPE （high density polyethylene）, LDPE （low density polyethylene） and Polypropylene were degraded. The reaction occurred in a semi batch reactor at several temperatures and catalyst/polymer ratios in search for an optimum operating condition. The products are liquid and gaseous hydrocarbons with minor of residue. The liquid and gas products were in the range of middle distillate cuts of gasoline, kerosene and gas oil. Finally, with a metallic base, yielded 99.5% of given mixed to valuable middle distillate products that include 86% liquid hydrocarbon and 13.5% gas, ranging between C1 and C5 with less percent of residue. The optimum condition for this yield reports at a temperature of 450 ℃ and 10% of catalyst w/w at atmosphere pressure.展开更多
Sustainable conversion of carbon dioxide(CO_(2))to high value-added chemicals and fuels is a promising solution to solve the problem of excessive CO_(2) emissions and alleviate the shortage of fossil fuels,maintaining...Sustainable conversion of carbon dioxide(CO_(2))to high value-added chemicals and fuels is a promising solution to solve the problem of excessive CO_(2) emissions and alleviate the shortage of fossil fuels,maintaining the balance of the carbon cycle in nature.The development of catalytic system is of great significance to improve the efficiency and selectivity for electrochemical CO_(2) conversion.In particular,bismuth(Bi)based catalysts are the most promising candidates,while confronting challenges.This review aims to elucidate the fundamental issues of efficient and stable Bi-based catalysts,constructing a bridge between the category,synthesis approach and electrochemical performance.In this review,the categories of Bi-based catalysts are firstly introduced,such as metals,alloys,single atoms,compounds and composites.Followed by the statement of the reliable and versatile synthetic approaches,the representative optimization strategies,such as morphology manipulation,defect engineering,component and heterostructure regulation,have been highlighted in the discussion,paving in-depth insight upon the design principles,reaction activity,selectivity and stability.Afterward,in situ characterization techniques will be discussed to illustrate the mechanisms of electrochemical CO_(2) conversion.In the end,the challenges and perspectives are also provided,promoting a systematic understanding in terms of the bottleneck and opportunities in the field of electrochemical CO_(2) conversion.展开更多
Learning from nature photosynthesis,the development of efficient artificial catalysts for water oxidation is an ongoing challenge.Herein,a lamellar cobalt oxide(CoO),black phosphorus(BP)and reduced graphene oxide(RGO)...Learning from nature photosynthesis,the development of efficient artificial catalysts for water oxidation is an ongoing challenge.Herein,a lamellar cobalt oxide(CoO),black phosphorus(BP)and reduced graphene oxide(RGO)hybrid electrocatalyst is reported.BP domains are anchored on RGO and coated with CoO via P–O bonds.The widespread P–O bond network constitutes the proton acceptor and forms a proton exit channel,akin to the use of Asp61 in Photosystem II(PSII).The innermost kernel layer RGO serves as the current collector and forms an electron exit channel,mimicking the function of Tyr161 for charge transfer.The outermost encapsulation CoO layer acts as water oxidation catalyst(WOC).These biology‐inspired features endow an outstanding OER performance of the hybrid material with a low overpotential of 206 mV at a current density of 10 mA cm^(-2).This work provides a new design guide for OER electrocatalysts through constructing two specialized channels for proton and electron transfer.展开更多
Transesterification between methyl-butyrate and 1-butanol in nonaqueous systems was catalyzed by porcine pancreatic lipase which was immobilized on cross- linked polystyrene. Organic solvents, substrate concentration,...Transesterification between methyl-butyrate and 1-butanol in nonaqueous systems was catalyzed by porcine pancreatic lipase which was immobilized on cross- linked polystyrene. Organic solvents, substrate concentration, contents of water and other parameters which affect the immobilized enzyme activity were studied. Lipase immobilized on hydrophobic crosslinked polystyrene can reduce its diffusion limit in the reaction. It was found that the activity of immobilized lipase in organic systems was two times as high as that of free lipase.展开更多
CO2 is a major greenhouse gas,and it can also be used as a chemical feedstock for synthesis of chemicals and fuels by passing the petrochemical source.Herein,we present the recent progress of our research work in the ...CO2 is a major greenhouse gas,and it can also be used as a chemical feedstock for synthesis of chemicals and fuels by passing the petrochemical source.Herein,we present the recent progress of our research work in the catalytic conversion of CO2 to chemicals,with particular attention paid to catalytic reactivity and reaction mechanism.We also give the recommendations regarding the challenges and potential directions of the future research in this field.展开更多
Oxidative coupling of α-bromoarylacetonitriles and oxidative decyanation of diarylacetonitriles are efficiently realized by solid-liquid phase transfer catalysis using anhydrous K 3 PO 4 as base and TBAB as catalyst ...Oxidative coupling of α-bromoarylacetonitriles and oxidative decyanation of diarylacetonitriles are efficiently realized by solid-liquid phase transfer catalysis using anhydrous K 3 PO 4 as base and TBAB as catalyst in acetone at room temperature. In this mild and convenient method, α,β-dicyanostilbenes and diarylketones were prepared in good to excellent yields.展开更多
基金supported by the National Key R&D Program(2017YFA0206804)the National Natural Science Foundation of China(21871021,21521005)the Fundamental Research Funds for the Central Universities(buctylkxj01,XK1802-6)~~
文摘Ethanol conversion to high-value-added products has attracted considerable attention in both academic research and industrial fields.In this study,we synthesized a series of tunable acid–base bifunctional Zn-Zr-Al metal oxides(represented as Zn2ZrxAl-MMO)in light of the structural topotactic transformation of Zn2ZrxAl-hydrotalcite precursors(Zn2ZrxAl-LDH).The resulting Zn2ZrxAl-MMO catalysts were employed in the conversion of ethanol to diethyl carbonate.The Zr^4+ ion content of the LDH precursor plays a key role in modulating the acid-base properties and determining catalytic performance:the Zn2Zr0.1Al-MMO sample exhibits the optimal catalytic behavior with a diethyl carbonate(DEC)yield of 42.1%,which is the highest reported for metal oxide catalysts.Structure-property correlation investigations revealed that the synergic catalysis between medium-strong basic sites and weak acid sites plays a predominant role in the catalytic behavior.Furthermore,in situ Fourier transform infrared measurements showed that the weak acidic site promotes activation adsorption of the reactant(urea)and the intermediate product(ethyl carbamate),while the medium-strong basic site accelerates ethanol activation.Moreover,the Zn2Zr0.1Al-MMO catalyst has the advantages of cost effectiveness,good stability,and reusability.Therefore,the acid-base bifunctional catalysts developed in this work can be employed as promising candidates in acid-base catalytic reactions such as ethanol conversion.
文摘Developing non‐noble‐metal electrocatalyst with efficient and durable activity is a urgent task for addressing the sluggish reaction kinetics of electrochemical water oxidation.Structural evolution of the electrocatalyst is an important strategy for achieving enhanced performance.Herein,in situ evolution of surface Co_(2)CrO_(4) to CoOOH/CrOOH(CoOOH/CrOOH‐Co_(2)CrO_(4))by an electrochemical method under alkaline conditions was designed for enhancing the electrocatalytic performance of water oxidation.The experiments demonstrated that the synergy between CoOOH/CrOOH and Co_(2)CrO_(4) resulted in a marked increase in the number of active sites and improved the rate of charge transfer,which enhanced the activity for water oxidation.At a geometrical current density of 20 mA cm^(−2),the overpotential of the oxygen evolution reaction was 244 mV and the turnover frequency was 0.536 s^(−1) in 1.0 M NaOH.
文摘Using novel catalyst the pyrolysis of mixed plastics has been considered as an effective way to convert waste plastics into environmental friendly and industrially useful hydrocarbon gas and liquid products. Catalytic cracking is a promising alternative for plastic wastes recycling. More than 99% of a polymer mixed converted into combustible hydrocarbon in a catalytic converting reaction. The products are mainly middle distillates. In this work equally weighted mixed HDPE （high density polyethylene）, LDPE （low density polyethylene） and Polypropylene were degraded. The reaction occurred in a semi batch reactor at several temperatures and catalyst/polymer ratios in search for an optimum operating condition. The products are liquid and gaseous hydrocarbons with minor of residue. The liquid and gas products were in the range of middle distillate cuts of gasoline, kerosene and gas oil. Finally, with a metallic base, yielded 99.5% of given mixed to valuable middle distillate products that include 86% liquid hydrocarbon and 13.5% gas, ranging between C1 and C5 with less percent of residue. The optimum condition for this yield reports at a temperature of 450 ℃ and 10% of catalyst w/w at atmosphere pressure.
文摘Sustainable conversion of carbon dioxide(CO_(2))to high value-added chemicals and fuels is a promising solution to solve the problem of excessive CO_(2) emissions and alleviate the shortage of fossil fuels,maintaining the balance of the carbon cycle in nature.The development of catalytic system is of great significance to improve the efficiency and selectivity for electrochemical CO_(2) conversion.In particular,bismuth(Bi)based catalysts are the most promising candidates,while confronting challenges.This review aims to elucidate the fundamental issues of efficient and stable Bi-based catalysts,constructing a bridge between the category,synthesis approach and electrochemical performance.In this review,the categories of Bi-based catalysts are firstly introduced,such as metals,alloys,single atoms,compounds and composites.Followed by the statement of the reliable and versatile synthetic approaches,the representative optimization strategies,such as morphology manipulation,defect engineering,component and heterostructure regulation,have been highlighted in the discussion,paving in-depth insight upon the design principles,reaction activity,selectivity and stability.Afterward,in situ characterization techniques will be discussed to illustrate the mechanisms of electrochemical CO_(2) conversion.In the end,the challenges and perspectives are also provided,promoting a systematic understanding in terms of the bottleneck and opportunities in the field of electrochemical CO_(2) conversion.
文摘Learning from nature photosynthesis,the development of efficient artificial catalysts for water oxidation is an ongoing challenge.Herein,a lamellar cobalt oxide(CoO),black phosphorus(BP)and reduced graphene oxide(RGO)hybrid electrocatalyst is reported.BP domains are anchored on RGO and coated with CoO via P–O bonds.The widespread P–O bond network constitutes the proton acceptor and forms a proton exit channel,akin to the use of Asp61 in Photosystem II(PSII).The innermost kernel layer RGO serves as the current collector and forms an electron exit channel,mimicking the function of Tyr161 for charge transfer.The outermost encapsulation CoO layer acts as water oxidation catalyst(WOC).These biology‐inspired features endow an outstanding OER performance of the hybrid material with a low overpotential of 206 mV at a current density of 10 mA cm^(-2).This work provides a new design guide for OER electrocatalysts through constructing two specialized channels for proton and electron transfer.
文摘Transesterification between methyl-butyrate and 1-butanol in nonaqueous systems was catalyzed by porcine pancreatic lipase which was immobilized on cross- linked polystyrene. Organic solvents, substrate concentration, contents of water and other parameters which affect the immobilized enzyme activity were studied. Lipase immobilized on hydrophobic crosslinked polystyrene can reduce its diffusion limit in the reaction. It was found that the activity of immobilized lipase in organic systems was two times as high as that of free lipase.
基金the financial support from the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA02040602)the National Science&Technology Pillar Program(2013BAC11B02)
文摘CO2 is a major greenhouse gas,and it can also be used as a chemical feedstock for synthesis of chemicals and fuels by passing the petrochemical source.Herein,we present the recent progress of our research work in the catalytic conversion of CO2 to chemicals,with particular attention paid to catalytic reactivity and reaction mechanism.We also give the recommendations regarding the challenges and potential directions of the future research in this field.
基金Natural Science Foundation of China (Grant No.NSFC 20672009)
文摘Oxidative coupling of α-bromoarylacetonitriles and oxidative decyanation of diarylacetonitriles are efficiently realized by solid-liquid phase transfer catalysis using anhydrous K 3 PO 4 as base and TBAB as catalyst in acetone at room temperature. In this mild and convenient method, α,β-dicyanostilbenes and diarylketones were prepared in good to excellent yields.
