A carbon supported Pd（Pd/C） catalyst used as the anodic catalyst in the direct formic acid fuel cells（DFAFC） was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate（EDTA） a...A carbon supported Pd（Pd/C） catalyst used as the anodic catalyst in the direct formic acid fuel cells（DFAFC） was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate（EDTA） as stabilizer and complexing agent. This method is very simple. The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity. The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.展开更多
Deactivation of Pd/C catalyst often occurs in liquid hydrogenation using industrial materials. For in-stance, the Pd/C catalyst is deactivated severely in the hydrogenation of N-(3-nitro-4-methoxyphenyl) acetamide. In...Deactivation of Pd/C catalyst often occurs in liquid hydrogenation using industrial materials. For in-stance, the Pd/C catalyst is deactivated severely in the hydrogenation of N-(3-nitro-4-methoxyphenyl) acetamide. In this study, the chemisorption of sulfur on the surface of deactivated Pd/C was detected by energy dispersive spec-trometer and X-ray photoelectron spectroscopy. Sulfur compounds poison the Pd/C catalyst and increase the forma-tion of azo deposit, reducing the activity of catalyst. We report a mild method to regenerate the Pd/C catalyst: wash the deposit by N,N-dimethylformamide and oxidize the chemisorbed sulfur by hot air. The regenerated Pd/C cata-lyst can be reused at least ten runs with stable activity.展开更多
Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corr...Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corresponding saturated aldehydes was achieved under mild conditions.This protocol provides an alternative for efficient preparation of saturated aldehydes.展开更多
In this study, diphenyl sulfide(Ph2S) was employed to prepare a series of Ph2S-modified Pd/C catalysts(Pd–Ph2S/C). Catalyst characterization carried out by Brunner–Emmet–Teller(BET), energy dispersive spectrometer(...In this study, diphenyl sulfide(Ph2S) was employed to prepare a series of Ph2S-modified Pd/C catalysts(Pd–Ph2S/C). Catalyst characterization carried out by Brunner–Emmet–Teller(BET), energy dispersive spectrometer(EDS), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and CO chemisorption uptake measurements suggested a chemical interaction between Ph2 S and Pd. The ligand was preferably absorbed on the active site of Pd metal but after increasing the amount of Ph2 S, the adsorption of Ph2 S on Pd metal tended to be saturated and the excess of Ph2 S partially adsorbed on the activated carbon. A part of Pd atoms without adsorbing any Ph2 S still existed, even for the saturated Pd–Ph2S/C catalyst. The Pd–Ph2S/C catalysts exhibited a good selectivity of p-chloroaniline(p-CAN) in the hydrogenation of p-chloronitrobenzene(p-CNB). However,the chemisorption between Ph2 S and Pd was not so strong that part of Ph2 S was leached from Pd–Ph2S/C catalyst during the hydrogenation, which caused the decline of the selectivity of p-CAN over the used Pd–Ph2S/C catalyst.Resulfidation of the used Pd–Ph2S/C catalyst was effective to resume its stability, and the regenerated Pd–Ph2S/C catalyst could be reused for at least ten runs with a stable catalytic performance.展开更多
Hydrogen generation from formic acid （FA） has received significant attention. The challenge is to obtain a highly active catalyst under mild conditions for practical applications. Here atomic layer deposition （ALD...Hydrogen generation from formic acid （FA） has received significant attention. The challenge is to obtain a highly active catalyst under mild conditions for practical applications. Here atomic layer deposition （ALD） of FeOx was performed to deposit an ultrathin oxide coating layer to a Pd/C catalyst, therein the FeOx coverage was precisely controlled by ALD cycles. Transmission electron microscopy and powder X-ray diffraction measurements suggest that the FeOx coating layer improved the thermal stability of Pd nanoparticles （NPs）. X-ray photoelectron spectroscopy measurement showed that deposition of FeOx on the Pd NPs caused a positive shift of Pd3d binding energy. In the FA dehydrogenation reaction, the ultrathin FeOx layer on the Pd/C could considerably improve the catalytic activity, and Pd/C coated with 8 cycles of FeOx showed an optimized activity with turnover frequency being about 2 times higher than the uncoated one. shape as a function of the number of FeOx ALD The improved activities were in a volcanocycles, indicating the coverage of FeOx is critical for the optimized activity. In summary, simultaneous improvements of activity and thermal stability of Pd/C catalyst by ultra-thin FeOx overlayer suggest to be an effective way to design active catalysts for the FA dehydrogenation reaction.展开更多
It has been found that cold plasma is a facile and environmentally benign method for synthesizing supported metal catalysts, and great efforts have been devoted to enlarging its applications. However, little work has ...It has been found that cold plasma is a facile and environmentally benign method for synthesizing supported metal catalysts, and great efforts have been devoted to enlarging its applications. However, little work has been done to disclose the influence mechanism, which is significant for controllable synthesis. In this work, hydrogen cold plasma was adopted to synthesize a palladium catalyst supported on activated carbon （Pd/C-P） using HzPdC14 as a Pd precursor followed by calcination in hydrogen gas to remove the chlorine ions. The Pd/C-P catalyst was found to be made of larger Pd nanoparticles showing a decreased migration to the support outer surface than that prepared by the conventional thermal hydrogen reduction method （Pd/C-C）. Meanwhile, the pore diameter of the activated carbon support is small （,-~4 nm）. Therefore, Pd/C-P exhibits lower CO oxidation activity than Pd/C-C. It was proposed that the strong interaction between the activated carbon and PdC142-, and the enhanced metal-support interaction caused by hydrogen cold plasma reduction made it difficult for Pd nanoparticles to migrate to the support outer surface. The larger-sized Pd nanoparticles for Pd/C-P may be due to the Coulomb interaction resulting in the disturbance of the metal-support interaction. This work has important guiding significance for the controllable synthesis of supported metal catalysts by hydrogen cold plasma.展开更多
The PTA unit at the Chemical Plant of SINOPEC Yizheng Chemical Fiber Company uses the MPB5 type Pd/C hydrofining catalyst jointly developed by German Sued-Chemie and Japan Catalyst Company. Currently the catalystservi...The PTA unit at the Chemical Plant of SINOPEC Yizheng Chemical Fiber Company uses the MPB5 type Pd/C hydrofining catalyst jointly developed by German Sued-Chemie and Japan Catalyst Company. Currently the catalystservice life has set a longest life among similar domestic catalysts.展开更多
A multifunctional porous organic polymer of POP-Nixantphos-PPh_(3)-PhSO_(3)Na was prepared by free radical tricopolymerization.Further loading of Pd(OAc)2 led to the catalyst of Pd/POP-Nixantphos-PPh_(3)-PhSO_(3)Na.In...A multifunctional porous organic polymer of POP-Nixantphos-PPh_(3)-PhSO_(3)Na was prepared by free radical tricopolymerization.Further loading of Pd(OAc)2 led to the catalyst of Pd/POP-Nixantphos-PPh_(3)-PhSO_(3)Na.In this catalyst,Nixantphos ligand moieties were employed to enhance the catalytic hydrocarboxylation activity of palladium.Additionally,PPh_(3)ligand moieties were utilized to construct a porous framework of catalyst that facilitated the dispersion of Pd nanoparticles as well as the diffusion of reactants and products.Furthermore,the incorporation of PhSO_(3)Na moieties improved the hydrophilicity of the support.With H_(2)O as the reaction solvent,under the initial CO pressure of 0.1 MPa,Pd/POP-Nixantphos-PPh3-PhSO3Na-catalyzed hydrocarboxylation of alkynes to afford the correspondingα,β-unsaturated carboxylic acids in good yields(76%~96%).Various alkynes,such as diaromatic alkynes,arylalkyl alkynes and dialkyl alkynes,worked well in the process.Additionally,the catalyst showed excellent recyclability with no significant yield loss over five cycles.展开更多
Efficient production of butanediols from biomass-derived feedstocks under mild reaction conditions is still of challenge.Here,we reported a highly efficient Pd-WO_(x) catalyst which was facilely synthesized by a simpl...Efficient production of butanediols from biomass-derived feedstocks under mild reaction conditions is still of challenge.Here,we reported a highly efficient Pd-WO_(x) catalyst which was facilely synthesized by a simple‘one pot’solvothermal method for the selective conversion of glucose and lignocellulosic biomass to butanediols with remarkable activity.The optimized process achieved an impressive 56.5%yield of butanediols at 180◦C within 8 h under a low hydrogen pressure of 0.6 MPa,surpassing most reported catalysts.Comprehensive characterization(H_(2)-TPR,XPS,NH3-TPD,etc.)revealed that Pd-WO_(x) not only enhanced H_(2) adsorption and activation but also possessed a higher density of acidic sites to promote selective cleavage of C-C bond in glucose structure,thereby significantly improving the efficiency of sustainable butanediols production.Furthermore,the catalyst demonstrated excellent stability over five reaction cycles.This work provides a viable and efficient strategy for sustainable biomass valorization to produce valuable butanediols.展开更多
Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The add...Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The addition of Pt to Pd-based catalysts is found to be the most effective and promising method.However,distinct states of existence of Pt can affect the catalytic performance to different degrees,even negatively.Therefore,the impact mechanism of Pt on Pd-based catalysts needs to be further understood.In this work,A-site defective La_(0.9)AlO_(x)perovskite was used as a support,and the state of Pt in catalysts was regulated by adjusting the introducing sequence of Pd and Pt,It is found that only when Pt is introduced preferentially,the activity and water resistance of the bimetal can be improved.Combining a series of characterization results of the fresh catalysts,reduced catalysts,and the samples after reduction and use,it is found that the higher Pt^(2+)content in the catalyst is the main reason for promoting bimetallic properties,while more Pt0has an inhibitory effect.This work provides a new understanding of the promotion effect of Pt on Pd-Pt bimetal in the catalytic oxidation reaction of methane.展开更多
A robust bulky bornylimidazo[1,5-a]pyridin-3-ylidene allylic Pd complex was synthesized and well characterized.DFT calculations indicated that the ligand acts as a strongσ-donor andπ-acceptor endowing the active Pd(...A robust bulky bornylimidazo[1,5-a]pyridin-3-ylidene allylic Pd complex was synthesized and well characterized.DFT calculations indicated that the ligand acts as a strongσ-donor andπ-acceptor endowing the active Pd(0)center with high electron density and good coordination towards olefin.The introduction of a bulky,rigid bornyl ring further improved the catalytic efficacy due to the matched steric effects.This catalyst showed high efficiency and versatility in theα-arylation and Heck cyclization/Suzuki crosscoupling reactions at mild reaction conditions.Desired 3,3-disubstituted oxindoles,especially featuring an allylic-derived C3-quaternary stereocenter were obtained in high yields.Furthermore,the concise synthesis of bioactive heterocycle-fused indoline alkaloids was successfully proved.展开更多
The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones （PK）was studied in the N-valeronitrile-N＆#39;-methylimidazolium hexafluorophosphate （[C4CNmim]＋PF6-） medium. The synth...The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones （PK）was studied in the N-valeronitrile-N＆#39;-methylimidazolium hexafluorophosphate （[C4CNmim]＋PF6-） medium. The synthe-sized PK was characterized by Fourier transform infrared（FTIR）, elemental analysis, 13C-nuclear magnetic resonance （13C-NMR）, differential scanning calorimetry （DSC）, thermogravimetric analysis （TGA） and gel permeation chro-matography （GPC）. The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%（0.1 g ionic liquid/1 g active carbon carrier） and the theoretical content of Pd2＋is 5wt%（0.05 g Pd2＋/1 g active car-bon carrier）, the highest catalytic activity 2 963.64 gSTCO/（gPd＆#183;h） is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw/Mn=1.389.展开更多
Pd/Ce0.67Zr0.33O2 catalyst was pretreated in different atmosphere respectively, and characterized by CO chemical adsorption, XPS, HR-TEM, H2-TPR, Raman, OSC and in situ DRIFTS to investigate the effect of the structur...Pd/Ce0.67Zr0.33O2 catalyst was pretreated in different atmosphere respectively, and characterized by CO chemical adsorption, XPS, HR-TEM, H2-TPR, Raman, OSC and in situ DRIFTS to investigate the effect of the structure properties of PdOx species on the catalytic performance for CO, HC and NOx elimination. The results show that Pd/CZ catalyst pretreated in air atmosphere has higher oxidation activity of HC due to having high Pd dispersion and strong interaction between PdOx and CZ support. Pd/CZ-H catalyst pretreated in reducing atmosphere exhibits better catalytic performance of NOx elimination because of having relatively big Pd particle size, more Pd species in metallic state and higher concentration of oxygen vacancies. While for the Pd/CZ-RG catalyst pretreated in reactant atmosphere, strong adsorption of HC species on the surface of catalysts would lead to a part of active sites being covered, which inhibits HC and NO conversions.展开更多
基金Supported by the "863" Program of Science and Technology Ministry of China(Nos.2006AA05Z137, 2007AA05Z143 and 2007AA05Z159)National Natural Science Foundation of China(Nos.20433060, 20473038, 20573057 and 20703043)the Natural Science Foundation of Jiangsu Province, China(No.BK2006224).
文摘A carbon supported Pd（Pd/C） catalyst used as the anodic catalyst in the direct formic acid fuel cells（DFAFC） was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate（EDTA） as stabilizer and complexing agent. This method is very simple. The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity. The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.
基金financial support from the Ministry of Science and Technology of China(Grant 2017YFA 0700102)the National Natural Science Foundation of China(Grants 21573222 and 91545202)+1 种基金Outstanding Youth Talent Project of Dalian(2017RJ03)Dalian Institute of Chemic
基金Supported by the Natural Science Foundation of Zhejiang Provincial （LYI2B03009） and Program for Zhejiang Leading Team of Science and Technology Innovation （2011 R09020-03）.
文摘Deactivation of Pd/C catalyst often occurs in liquid hydrogenation using industrial materials. For in-stance, the Pd/C catalyst is deactivated severely in the hydrogenation of N-(3-nitro-4-methoxyphenyl) acetamide. In this study, the chemisorption of sulfur on the surface of deactivated Pd/C was detected by energy dispersive spec-trometer and X-ray photoelectron spectroscopy. Sulfur compounds poison the Pd/C catalyst and increase the forma-tion of azo deposit, reducing the activity of catalyst. We report a mild method to regenerate the Pd/C catalyst: wash the deposit by N,N-dimethylformamide and oxidize the chemisorbed sulfur by hot air. The regenerated Pd/C cata-lyst can be reused at least ten runs with stable activity.
基金supported by the National High Technology Research and Development Program of China(863 Project)(No.2007AA03Z345)the Scientific Research Project for Institute of Higher Education of Education Bureau,Liaoning(No.LT2010021)the Fundamental Research Funds for Dalian University of Technology(No.DUT10RC(3)107)
文摘Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corresponding saturated aldehydes was achieved under mild conditions.This protocol provides an alternative for efficient preparation of saturated aldehydes.
基金Supported by National Basic Research Program of China(2011CB710800)Zhejiang Provincial Natural Science Foundation of China(LY12B03009)
文摘In this study, diphenyl sulfide(Ph2S) was employed to prepare a series of Ph2S-modified Pd/C catalysts(Pd–Ph2S/C). Catalyst characterization carried out by Brunner–Emmet–Teller(BET), energy dispersive spectrometer(EDS), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and CO chemisorption uptake measurements suggested a chemical interaction between Ph2 S and Pd. The ligand was preferably absorbed on the active site of Pd metal but after increasing the amount of Ph2 S, the adsorption of Ph2 S on Pd metal tended to be saturated and the excess of Ph2 S partially adsorbed on the activated carbon. A part of Pd atoms without adsorbing any Ph2 S still existed, even for the saturated Pd–Ph2S/C catalyst. The Pd–Ph2S/C catalysts exhibited a good selectivity of p-chloroaniline(p-CAN) in the hydrogenation of p-chloronitrobenzene(p-CNB). However,the chemisorption between Ph2 S and Pd was not so strong that part of Ph2 S was leached from Pd–Ph2S/C catalyst during the hydrogenation, which caused the decline of the selectivity of p-CAN over the used Pd–Ph2S/C catalyst.Resulfidation of the used Pd–Ph2S/C catalyst was effective to resume its stability, and the regenerated Pd–Ph2S/C catalyst could be reused for at least ten runs with a stable catalytic performance.
基金This work was supported by the National Natural Science Foundation of China （No.51402283 and No.21473169）, One Thousand Young Talents Program under the Recruitment Program of Global Experts, the Fundamental Research Funds for the Central Universi- ties （No.WK2060030017）, and the Startup Funds from University of Science and Technology of China.
文摘Hydrogen generation from formic acid （FA） has received significant attention. The challenge is to obtain a highly active catalyst under mild conditions for practical applications. Here atomic layer deposition （ALD） of FeOx was performed to deposit an ultrathin oxide coating layer to a Pd/C catalyst, therein the FeOx coverage was precisely controlled by ALD cycles. Transmission electron microscopy and powder X-ray diffraction measurements suggest that the FeOx coating layer improved the thermal stability of Pd nanoparticles （NPs）. X-ray photoelectron spectroscopy measurement showed that deposition of FeOx on the Pd NPs caused a positive shift of Pd3d binding energy. In the FA dehydrogenation reaction, the ultrathin FeOx layer on the Pd/C could considerably improve the catalytic activity, and Pd/C coated with 8 cycles of FeOx showed an optimized activity with turnover frequency being about 2 times higher than the uncoated one. shape as a function of the number of FeOx ALD The improved activities were in a volcanocycles, indicating the coverage of FeOx is critical for the optimized activity. In summary, simultaneous improvements of activity and thermal stability of Pd/C catalyst by ultra-thin FeOx overlayer suggest to be an effective way to design active catalysts for the FA dehydrogenation reaction.
基金supported by National Natural Science Foundation of China (Grant Nos. 11505019, 21673026)Dalian Youth Science and Technology Project (Grant No. 2015R089)
文摘It has been found that cold plasma is a facile and environmentally benign method for synthesizing supported metal catalysts, and great efforts have been devoted to enlarging its applications. However, little work has been done to disclose the influence mechanism, which is significant for controllable synthesis. In this work, hydrogen cold plasma was adopted to synthesize a palladium catalyst supported on activated carbon （Pd/C-P） using HzPdC14 as a Pd precursor followed by calcination in hydrogen gas to remove the chlorine ions. The Pd/C-P catalyst was found to be made of larger Pd nanoparticles showing a decreased migration to the support outer surface than that prepared by the conventional thermal hydrogen reduction method （Pd/C-C）. Meanwhile, the pore diameter of the activated carbon support is small （,-~4 nm）. Therefore, Pd/C-P exhibits lower CO oxidation activity than Pd/C-C. It was proposed that the strong interaction between the activated carbon and PdC142-, and the enhanced metal-support interaction caused by hydrogen cold plasma reduction made it difficult for Pd nanoparticles to migrate to the support outer surface. The larger-sized Pd nanoparticles for Pd/C-P may be due to the Coulomb interaction resulting in the disturbance of the metal-support interaction. This work has important guiding significance for the controllable synthesis of supported metal catalysts by hydrogen cold plasma.
文摘The PTA unit at the Chemical Plant of SINOPEC Yizheng Chemical Fiber Company uses the MPB5 type Pd/C hydrofining catalyst jointly developed by German Sued-Chemie and Japan Catalyst Company. Currently the catalystservice life has set a longest life among similar domestic catalysts.
文摘A multifunctional porous organic polymer of POP-Nixantphos-PPh_(3)-PhSO_(3)Na was prepared by free radical tricopolymerization.Further loading of Pd(OAc)2 led to the catalyst of Pd/POP-Nixantphos-PPh_(3)-PhSO_(3)Na.In this catalyst,Nixantphos ligand moieties were employed to enhance the catalytic hydrocarboxylation activity of palladium.Additionally,PPh_(3)ligand moieties were utilized to construct a porous framework of catalyst that facilitated the dispersion of Pd nanoparticles as well as the diffusion of reactants and products.Furthermore,the incorporation of PhSO_(3)Na moieties improved the hydrophilicity of the support.With H_(2)O as the reaction solvent,under the initial CO pressure of 0.1 MPa,Pd/POP-Nixantphos-PPh3-PhSO3Na-catalyzed hydrocarboxylation of alkynes to afford the correspondingα,β-unsaturated carboxylic acids in good yields(76%~96%).Various alkynes,such as diaromatic alkynes,arylalkyl alkynes and dialkyl alkynes,worked well in the process.Additionally,the catalyst showed excellent recyclability with no significant yield loss over five cycles.
基金financial support from State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105287-MS202203)Chongqing Human Resources and Social Security Bureau Project(cx2024049)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0458).
文摘Efficient production of butanediols from biomass-derived feedstocks under mild reaction conditions is still of challenge.Here,we reported a highly efficient Pd-WO_(x) catalyst which was facilely synthesized by a simple‘one pot’solvothermal method for the selective conversion of glucose and lignocellulosic biomass to butanediols with remarkable activity.The optimized process achieved an impressive 56.5%yield of butanediols at 180◦C within 8 h under a low hydrogen pressure of 0.6 MPa,surpassing most reported catalysts.Comprehensive characterization(H_(2)-TPR,XPS,NH3-TPD,etc.)revealed that Pd-WO_(x) not only enhanced H_(2) adsorption and activation but also possessed a higher density of acidic sites to promote selective cleavage of C-C bond in glucose structure,thereby significantly improving the efficiency of sustainable butanediols production.Furthermore,the catalyst demonstrated excellent stability over five reaction cycles.This work provides a viable and efficient strategy for sustainable biomass valorization to produce valuable butanediols.
基金Project supported by the National Key Research and Development Program(2022YFB3504200)National Natrual Science Foundation of China(22376061,21922602,22076047,U21A20326)+1 种基金Shanghai Science and Technology Innovation Action Plan(20dz1204200)Fundamental Re search Funds for the Central Universities。
文摘Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The addition of Pt to Pd-based catalysts is found to be the most effective and promising method.However,distinct states of existence of Pt can affect the catalytic performance to different degrees,even negatively.Therefore,the impact mechanism of Pt on Pd-based catalysts needs to be further understood.In this work,A-site defective La_(0.9)AlO_(x)perovskite was used as a support,and the state of Pt in catalysts was regulated by adjusting the introducing sequence of Pd and Pt,It is found that only when Pt is introduced preferentially,the activity and water resistance of the bimetal can be improved.Combining a series of characterization results of the fresh catalysts,reduced catalysts,and the samples after reduction and use,it is found that the higher Pt^(2+)content in the catalyst is the main reason for promoting bimetallic properties,while more Pt0has an inhibitory effect.This work provides a new understanding of the promotion effect of Pt on Pd-Pt bimetal in the catalytic oxidation reaction of methane.
基金Financial supports from the National Natural Science Foundation of China(No.22101133)Natural Science Foundation of Jiangsu Province(No.BK20200768)+1 种基金Nanjing Forestry University,the National Natural Science Foundation of China(the Outstanding Youth Scholars(Overseas,2021)project)the Lab project of the State Key Laboratory of Physical Chemistry of Solid Surfaces are greatly acknowledged.
文摘A robust bulky bornylimidazo[1,5-a]pyridin-3-ylidene allylic Pd complex was synthesized and well characterized.DFT calculations indicated that the ligand acts as a strongσ-donor andπ-acceptor endowing the active Pd(0)center with high electron density and good coordination towards olefin.The introduction of a bulky,rigid bornyl ring further improved the catalytic efficacy due to the matched steric effects.This catalyst showed high efficiency and versatility in theα-arylation and Heck cyclization/Suzuki crosscoupling reactions at mild reaction conditions.Desired 3,3-disubstituted oxindoles,especially featuring an allylic-derived C3-quaternary stereocenter were obtained in high yields.Furthermore,the concise synthesis of bioactive heterocycle-fused indoline alkaloids was successfully proved.
基金Supported by the Tianjin Natural Science Foundation(No.07JCYBJC00600)
文摘The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones （PK）was studied in the N-valeronitrile-N＆#39;-methylimidazolium hexafluorophosphate （[C4CNmim]＋PF6-） medium. The synthe-sized PK was characterized by Fourier transform infrared（FTIR）, elemental analysis, 13C-nuclear magnetic resonance （13C-NMR）, differential scanning calorimetry （DSC）, thermogravimetric analysis （TGA） and gel permeation chro-matography （GPC）. The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%（0.1 g ionic liquid/1 g active carbon carrier） and the theoretical content of Pd2＋is 5wt%（0.05 g Pd2＋/1 g active car-bon carrier）, the highest catalytic activity 2 963.64 gSTCO/（gPd＆#183;h） is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw/Mn=1.389.
基金Project supported by the Key Program of Science Technology Department of Zhejiang Province(2018C03037)
文摘Pd/Ce0.67Zr0.33O2 catalyst was pretreated in different atmosphere respectively, and characterized by CO chemical adsorption, XPS, HR-TEM, H2-TPR, Raman, OSC and in situ DRIFTS to investigate the effect of the structure properties of PdOx species on the catalytic performance for CO, HC and NOx elimination. The results show that Pd/CZ catalyst pretreated in air atmosphere has higher oxidation activity of HC due to having high Pd dispersion and strong interaction between PdOx and CZ support. Pd/CZ-H catalyst pretreated in reducing atmosphere exhibits better catalytic performance of NOx elimination because of having relatively big Pd particle size, more Pd species in metallic state and higher concentration of oxygen vacancies. While for the Pd/CZ-RG catalyst pretreated in reactant atmosphere, strong adsorption of HC species on the surface of catalysts would lead to a part of active sites being covered, which inhibits HC and NO conversions.
