In this study,Ag/γ-Al_(2)O_(3)catalysts were synthesized by an Ar dielectric barrier discharge plasma using silver nitrate as the Ag source andγ-alumina(γ-Al_(2)O_(3))as the support.It is revealed that plasma can r...In this study,Ag/γ-Al_(2)O_(3)catalysts were synthesized by an Ar dielectric barrier discharge plasma using silver nitrate as the Ag source andγ-alumina(γ-Al_(2)O_(3))as the support.It is revealed that plasma can reduce silver ions to generate crystalline silver nanoparticles(Ag NPs)of good dispersion and uniformity on the alumina surface,leading to the formation of Ag/γ-Al_(2)O_(3)catalysts in a green manner without traditional chemical reductants.Ag/γ-Al_(2)O_(3)exhibited good catalytic activity and stability in CO oxidation reactions,and the activity increased with increase in the Ag content.For catalysts with more than 2 wt%Ag,100%CO conversion can be achieved at 300°C.The catalytic activity of the Ag/γ-Al_(2)O_(3)catalysts is also closely related to the size of theγ-alumina,where Ag/nano-γ-Al_(2)O_(3)catalysts demonstrate better performance than Ag/micro-γ-Al_(2)O_(3)catalysts with the same Ag content.In addition,the catalytic properties of plasma-generated Ag/nano-γ-Al_(2)O_(3)(Ag/γ-Al_(2)O_(3)-P)catalysts were compared with those of Ag/nano-γ-Al_(2)O_(3)catalysts prepared by the traditional calcination approach(Ag/γ-Al_(2)O_(3)-C),with the plasma-generated samples demonstrating better overall performance.This simple,rapid and green plasma process is considered to be applicable for the synthesis of diverse noble metal-based catalysts.展开更多
In order to improve the photocatalytic performance of mesoporous titania under visible light, a series of photocatalysts of S and Ag co-doped mesoporous titania have been successfully prepared by template method using...In order to improve the photocatalytic performance of mesoporous titania under visible light, a series of photocatalysts of S and Ag co-doped mesoporous titania have been successfully prepared by template method using thiourea, AgNO3 and tetrabutyl titanate as precursors and Pluronic P123 （EO20PO70EO20） as template. Scanning electron microscopy （SEM）, X-ray diffraction （XRD）, nitrogen adsorption-desorption measurements, and UV-visible spectroscopy （UV-Vis） were employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The microcrystal of the photocatalysts consisted of anatase phase and was approximately present in the form of spherical particle. The photocatalytic performance was studied by photodegradation methyl orange （MO） in water under UV and visible light irradiation. The calcination temperature and the doping content influenced the photoactivity. In addition, the possibility of cyclic usage of co-doped mesoporous titania was also confirmed, the photocatalytic activity of mesoporous titania remained above 89% of that of the fresh sample after being used four times. It was shown that the co-doped mesoporous titania could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants. The synergistic effect of sulfur and silver co-doping played an important role in improving the photocatalytic activity.展开更多
针对C-HRA-3耐热合金在700℃和750℃时效后的试样研究了M 23 C 6碳化物和γ′相化学相组成变化规律。结果表明:C-HRA-3合金经高温时效后析出M 23 C 6碳化物和γ′相,其中M 23 C 6碳化物中合金元素M为Cr、Mo、Ni和Co,γ′相中合金元素有N...针对C-HRA-3耐热合金在700℃和750℃时效后的试样研究了M 23 C 6碳化物和γ′相化学相组成变化规律。结果表明:C-HRA-3合金经高温时效后析出M 23 C 6碳化物和γ′相,其中M 23 C 6碳化物中合金元素M为Cr、Mo、Ni和Co,γ′相中合金元素有Ni、Co、Al、Ti、Mo、Cr和Nb,时效至8000 h后,700℃时效后M 23 C 6碳化物析出量约0.978%,γ′相析出量约9.5%;750℃时效后,M 23 C 6碳化物析出量约1.023%,γ′相析出量约6.753%,随时效温度升高,M 23 C 6碳化物析出量增加约4.6%,γ′相析出量减小约28.9%。展开更多
The inert carbon–carbon(C–C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C–C b...The inert carbon–carbon(C–C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C–C bonds in mixed polyolefin plastics over non-noble metal catalysts under mild conditions. The nickelbased catalyst involving Ni_(2)Al_(3) phase enables the direct transformation of mixed polyolefin plastics into natural gas, and the gas carbon yield reaches up to 89.6%. Reaction pathway investigation reveals that natural gas comes from the stepwise catalytic cleavage of C–C bonds in polypropylene, and the catalyst prefers catalytic cleavage of terminal C–C bond in the side-chain with the low energy barrier.Additionally, our developed approach is evaluated by the technical economic analysis for an economically competitive production process.展开更多
A series of perovskite type oxides and supported Ag catalysts were prepared, and characterized by X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS). The catalytic activities of the catalyst...A series of perovskite type oxides and supported Ag catalysts were prepared, and characterized by X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS). The catalytic activities of the catalysts as well as influencing factors on catalytic activity have been investigated for the simultaneous removal of NOx and diesel soot particulate. An increase in catalytic activity for the selective reduction of NOx was observed with Ag addition in these perovskite oxides, especially with 5% Ag loading. This catalyst could be a promising candidate of catalytic material for the simultaneous elimination of NOx and diesel soot.展开更多
A novel plasmonic photo‐Fenton catalyst of Ag/AgCl/Fe‐S was synthesized by ion exchange and photoreduction methods.The obtained catalyst was characterized by X‐ray diffraction,X‐ray photoelectron spectroscopy,scan...A novel plasmonic photo‐Fenton catalyst of Ag/AgCl/Fe‐S was synthesized by ion exchange and photoreduction methods.The obtained catalyst was characterized by X‐ray diffraction,X‐ray photoelectron spectroscopy,scanning electron microscope imaging,and Brunauer‐Emmett‐Teller measurements.Moreover,the photocatalytic activity of Ag/AgCl/Fe‐S was investigated for its degradation activity towards bisphenol A(BPA)as target pollutant under visible light irradiation.The effects of H2O2concentration,pH value,illumination intensity,and catalyst dosage on BPA degradation were examined.Our results indicated that the Ag/AgCl material was successfully loaded onto Fe‐sepiolite and showed a high photocatalytic activity under illumination by visible light.Furthermore,active species capture experiments were performed to explore the photocatalytic mechanism of the Ag/AgCl/Fe‐S in this heterogeneous photo‐Fenton process,where the major active species included hydroxyl radicals(?OH)and holes(h+).展开更多
Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized b...Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.展开更多
Catalytic hydrogenation of CO_(2) using renewable hydrogen not only reduces greenhouse gas emissions,but also provides industrial chemicals.Herein,a Co-Fe bimetallic catalyst was developed by a facile reactive ball-mi...Catalytic hydrogenation of CO_(2) using renewable hydrogen not only reduces greenhouse gas emissions,but also provides industrial chemicals.Herein,a Co-Fe bimetallic catalyst was developed by a facile reactive ball-milling method for highly active and selective hydrogenation of CO_(2) to value-added hydrocarbons.When reacted at 320℃,1.0 MPa and 9600 mL h^(-1) g_(cat)^(-1),the selectivity to light olefin(C_(2)^(=)-C_(4)^(=)) and C_(5)+ species achieves 57.3% and 22.3%,respectively,at a CO_(2) co nversion of 31.4%,which is superior to previous Fe-based catalysts.The CO_(2) activation can be promoted by the CoFe phase formed by reactive ball milling of the Fe-Co_(3)O_(4) mixture,and the in-situ Co_(2)C and Fe_(5)C_(2) formed during hydrogenation are beneficial for the C-C coupling reaction.The initial C-C coupling is related to the combination of CO species with the surface carbon of Fe/Co carbides,and the sustained C-C coupling is maintained by self-recovery of defective carbides.This new strategy contributes to the development of efficient catalysts for the hydrogenation of CO_(2) to value-added hydrocarbons.展开更多
The base-free aerobic oxidation of 5-hydroxymethylfurfural(HMF) to 2,5-furandicarboxylic acid(FDCA)in water is recognized as an important and sustainable upgrading process for cellulosic carbohydrates.However,selectiv...The base-free aerobic oxidation of 5-hydroxymethylfurfural(HMF) to 2,5-furandicarboxylic acid(FDCA)in water is recognized as an important and sustainable upgrading process for cellulosic carbohydrates.However,selectivity control still remains a challenge.Here,we disclose that the unique synergy in magnetic Ni_(x)Co_(1)O_(y)(x=1,3 and 5) bimetallic oxides can induce reactive oxygen defects and simultaneously stabilize small-sized metallic Au nanoparticles in the Au/Ni_(x)Co_(1)O_(y)catalysts.Such catalytic features render effective adsorption and activation of O_(2),OH and C=O groups,realizing selective oxidation of HMF to FDCA.On a series of magnetic Au/Ni_(x)Co_(1)O_(y)catalysts with almost identical Au loadings(ca.0.5 wt%) and particle sizes(ca.2.7 nm),the variable Ni/Co molar ratios give rise to the tunable electron density of Au sites and synergistic effect between NiO and CoO_(y).The initial conversion rates of HMF and its derived intermediates(i.e., DFF,HMFCA and FFCA) show a volcano-like dependence on the number of oxygen defects(i.e.,O_(2)^(-)and O^(-)) and electron-rich Au0sites.The optimum Au/Ni3Co1Oycatalyst exhibits a highest productivity of FDCA(12.5 mmol_(FDCA)mol_(Au)^(-1)h^(-1)) among all the Au catalysts in the literature and achieves> 99% yield of FDCA at 120℃ and 10 bar of O_(2).In addition,this catalyst can be easily recovered by a magnet and show superior stability and reusability during six consecutive cycling tests.This work may shed a light on Au catalysis for the base-free oxidation of biomass compounds by smartly using the synergy in bimetallic oxide carriers.展开更多
Methyl glycolate is a good solvent and can be used as feedstock for the synthesis of some important organic chemicals. Catalytic hydrogenation of dimethyl oxalate （DMO） over copper-silver catalyst supported on silic...Methyl glycolate is a good solvent and can be used as feedstock for the synthesis of some important organic chemicals. Catalytic hydrogenation of dimethyl oxalate （DMO） over copper-silver catalyst supported on silica was studied. The Cu-Ag/SiO2 catalyst supported on silica sol was prepared by homogeneous deposition-precipitation of the mixture of aqueous euprammonia complex and silica sol. The proper active temperature of Cu-Ag/SiO2 catalyst for hydrogenation of DMO was 523-623 K. The most preferable reaction conditions for methyl glycolate （MG） were optimized： temperature at 468-478 K, 40-60 mesh catalyst diameter, H2/DMO ratio 40, and 1.0 h^-1 of LHSV.展开更多
基金financial support from National Natural Science Foundation of China(Nos.52004102 and 22078125)Postdoctoral Science Foundation of China(No.2021M690068)+2 种基金Fundamental Research Funds for the Central Universities(Nos.JUSRP221018 and JUSRP622038)Key Laboratory of Green Cleaning Technology and Detergent of Zhejiang Province(No.Q202204)Open Project of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(No.GCP202112)。
文摘In this study,Ag/γ-Al_(2)O_(3)catalysts were synthesized by an Ar dielectric barrier discharge plasma using silver nitrate as the Ag source andγ-alumina(γ-Al_(2)O_(3))as the support.It is revealed that plasma can reduce silver ions to generate crystalline silver nanoparticles(Ag NPs)of good dispersion and uniformity on the alumina surface,leading to the formation of Ag/γ-Al_(2)O_(3)catalysts in a green manner without traditional chemical reductants.Ag/γ-Al_(2)O_(3)exhibited good catalytic activity and stability in CO oxidation reactions,and the activity increased with increase in the Ag content.For catalysts with more than 2 wt%Ag,100%CO conversion can be achieved at 300°C.The catalytic activity of the Ag/γ-Al_(2)O_(3)catalysts is also closely related to the size of theγ-alumina,where Ag/nano-γ-Al_(2)O_(3)catalysts demonstrate better performance than Ag/micro-γ-Al_(2)O_(3)catalysts with the same Ag content.In addition,the catalytic properties of plasma-generated Ag/nano-γ-Al_(2)O_(3)(Ag/γ-Al_(2)O_(3)-P)catalysts were compared with those of Ag/nano-γ-Al_(2)O_(3)catalysts prepared by the traditional calcination approach(Ag/γ-Al_(2)O_(3)-C),with the plasma-generated samples demonstrating better overall performance.This simple,rapid and green plasma process is considered to be applicable for the synthesis of diverse noble metal-based catalysts.
基金This work was supported by the National Natural Sci- ence Foundation of China （No.41373127） and the Liaoning Provincial Natural Science Foundation of China （No.2013020121）.
文摘In order to improve the photocatalytic performance of mesoporous titania under visible light, a series of photocatalysts of S and Ag co-doped mesoporous titania have been successfully prepared by template method using thiourea, AgNO3 and tetrabutyl titanate as precursors and Pluronic P123 （EO20PO70EO20） as template. Scanning electron microscopy （SEM）, X-ray diffraction （XRD）, nitrogen adsorption-desorption measurements, and UV-visible spectroscopy （UV-Vis） were employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The microcrystal of the photocatalysts consisted of anatase phase and was approximately present in the form of spherical particle. The photocatalytic performance was studied by photodegradation methyl orange （MO） in water under UV and visible light irradiation. The calcination temperature and the doping content influenced the photoactivity. In addition, the possibility of cyclic usage of co-doped mesoporous titania was also confirmed, the photocatalytic activity of mesoporous titania remained above 89% of that of the fresh sample after being used four times. It was shown that the co-doped mesoporous titania could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants. The synergistic effect of sulfur and silver co-doping played an important role in improving the photocatalytic activity.
文摘针对C-HRA-3耐热合金在700℃和750℃时效后的试样研究了M 23 C 6碳化物和γ′相化学相组成变化规律。结果表明:C-HRA-3合金经高温时效后析出M 23 C 6碳化物和γ′相,其中M 23 C 6碳化物中合金元素M为Cr、Mo、Ni和Co,γ′相中合金元素有Ni、Co、Al、Ti、Mo、Cr和Nb,时效至8000 h后,700℃时效后M 23 C 6碳化物析出量约0.978%,γ′相析出量约9.5%;750℃时效后,M 23 C 6碳化物析出量约1.023%,γ′相析出量约6.753%,随时效温度升高,M 23 C 6碳化物析出量增加约4.6%,γ′相析出量减小约28.9%。
基金supported by the National Natural Science Foundation of China (grant 22208339)the China Postdoctoral Science Foundation (2021M693132)+2 种基金the National Key R&D Program of China (2019YFC1905303)the Doctoral Scientific Research Foundation of Liaoning Province (2021-BS-006)the Youth Innovation Fund of Dalian Institute of Chemical Physics (DICP I202132)。
文摘The inert carbon–carbon(C–C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C–C bonds in mixed polyolefin plastics over non-noble metal catalysts under mild conditions. The nickelbased catalyst involving Ni_(2)Al_(3) phase enables the direct transformation of mixed polyolefin plastics into natural gas, and the gas carbon yield reaches up to 89.6%. Reaction pathway investigation reveals that natural gas comes from the stepwise catalytic cleavage of C–C bonds in polypropylene, and the catalyst prefers catalytic cleavage of terminal C–C bond in the side-chain with the low energy barrier.Additionally, our developed approach is evaluated by the technical economic analysis for an economically competitive production process.
文摘A series of perovskite type oxides and supported Ag catalysts were prepared, and characterized by X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS). The catalytic activities of the catalysts as well as influencing factors on catalytic activity have been investigated for the simultaneous removal of NOx and diesel soot particulate. An increase in catalytic activity for the selective reduction of NOx was observed with Ag addition in these perovskite oxides, especially with 5% Ag loading. This catalyst could be a promising candidate of catalytic material for the simultaneous elimination of NOx and diesel soot.
基金supported by the National Natural Science Foundation of China(41573118)Research Foundation of Education Bureau of Hunan Province,China(14B177)Special Project of Xiangtan University~~
文摘A novel plasmonic photo‐Fenton catalyst of Ag/AgCl/Fe‐S was synthesized by ion exchange and photoreduction methods.The obtained catalyst was characterized by X‐ray diffraction,X‐ray photoelectron spectroscopy,scanning electron microscope imaging,and Brunauer‐Emmett‐Teller measurements.Moreover,the photocatalytic activity of Ag/AgCl/Fe‐S was investigated for its degradation activity towards bisphenol A(BPA)as target pollutant under visible light irradiation.The effects of H2O2concentration,pH value,illumination intensity,and catalyst dosage on BPA degradation were examined.Our results indicated that the Ag/AgCl material was successfully loaded onto Fe‐sepiolite and showed a high photocatalytic activity under illumination by visible light.Furthermore,active species capture experiments were performed to explore the photocatalytic mechanism of the Ag/AgCl/Fe‐S in this heterogeneous photo‐Fenton process,where the major active species included hydroxyl radicals(?OH)and holes(h+).
基金supported by National Basic Research Program of China (2013CB933200)Commission of Science and Technology of Shanghai Municipality (15DZ1205305)~~
文摘Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.
基金supported by the National Natural Science Foundation of China (22008098, 21978156, 42002040)the Program for Innovative Research Team (in Science and Technology) in University of Henan Province (21IRTSTHN004)+1 种基金the Program for Science & Technology Innovation Talents in Universities of Henan Province (22HASTIT008)the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering (2022-K34)。
文摘Catalytic hydrogenation of CO_(2) using renewable hydrogen not only reduces greenhouse gas emissions,but also provides industrial chemicals.Herein,a Co-Fe bimetallic catalyst was developed by a facile reactive ball-milling method for highly active and selective hydrogenation of CO_(2) to value-added hydrocarbons.When reacted at 320℃,1.0 MPa and 9600 mL h^(-1) g_(cat)^(-1),the selectivity to light olefin(C_(2)^(=)-C_(4)^(=)) and C_(5)+ species achieves 57.3% and 22.3%,respectively,at a CO_(2) co nversion of 31.4%,which is superior to previous Fe-based catalysts.The CO_(2) activation can be promoted by the CoFe phase formed by reactive ball milling of the Fe-Co_(3)O_(4) mixture,and the in-situ Co_(2)C and Fe_(5)C_(2) formed during hydrogenation are beneficial for the C-C coupling reaction.The initial C-C coupling is related to the combination of CO species with the surface carbon of Fe/Co carbides,and the sustained C-C coupling is maintained by self-recovery of defective carbides.This new strategy contributes to the development of efficient catalysts for the hydrogenation of CO_(2) to value-added hydrocarbons.
基金supported by the National Natural Science Foundation of China(22272149,22062025,21763031)the Yunnan Fundamental Research Projects(202001AW070012,202101AT070171)+3 种基金the Yunnan University’s Research Innovation Fund for Graduate Students(KC-22221892)the Open Research Fund of School of Chemistry and Chemical Engineering of Henan Normal Universitythe Workstation of Academician Chen Jing of Yunnan Province(202105AF150012)the Free Exploration Fund for Academician(202205AA160007)。
文摘The base-free aerobic oxidation of 5-hydroxymethylfurfural(HMF) to 2,5-furandicarboxylic acid(FDCA)in water is recognized as an important and sustainable upgrading process for cellulosic carbohydrates.However,selectivity control still remains a challenge.Here,we disclose that the unique synergy in magnetic Ni_(x)Co_(1)O_(y)(x=1,3 and 5) bimetallic oxides can induce reactive oxygen defects and simultaneously stabilize small-sized metallic Au nanoparticles in the Au/Ni_(x)Co_(1)O_(y)catalysts.Such catalytic features render effective adsorption and activation of O_(2),OH and C=O groups,realizing selective oxidation of HMF to FDCA.On a series of magnetic Au/Ni_(x)Co_(1)O_(y)catalysts with almost identical Au loadings(ca.0.5 wt%) and particle sizes(ca.2.7 nm),the variable Ni/Co molar ratios give rise to the tunable electron density of Au sites and synergistic effect between NiO and CoO_(y).The initial conversion rates of HMF and its derived intermediates(i.e., DFF,HMFCA and FFCA) show a volcano-like dependence on the number of oxygen defects(i.e.,O_(2)^(-)and O^(-)) and electron-rich Au0sites.The optimum Au/Ni3Co1Oycatalyst exhibits a highest productivity of FDCA(12.5 mmol_(FDCA)mol_(Au)^(-1)h^(-1)) among all the Au catalysts in the literature and achieves> 99% yield of FDCA at 120℃ and 10 bar of O_(2).In addition,this catalyst can be easily recovered by a magnet and show superior stability and reusability during six consecutive cycling tests.This work may shed a light on Au catalysis for the base-free oxidation of biomass compounds by smartly using the synergy in bimetallic oxide carriers.
文摘Methyl glycolate is a good solvent and can be used as feedstock for the synthesis of some important organic chemicals. Catalytic hydrogenation of dimethyl oxalate （DMO） over copper-silver catalyst supported on silica was studied. The Cu-Ag/SiO2 catalyst supported on silica sol was prepared by homogeneous deposition-precipitation of the mixture of aqueous euprammonia complex and silica sol. The proper active temperature of Cu-Ag/SiO2 catalyst for hydrogenation of DMO was 523-623 K. The most preferable reaction conditions for methyl glycolate （MG） were optimized： temperature at 468-478 K, 40-60 mesh catalyst diameter, H2/DMO ratio 40, and 1.0 h^-1 of LHSV.
