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
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
Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticle...Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen source.The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 addition.The hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd NPs.This process helped to improve metal dispersion.The increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF catalyst.Furthermore,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction process.This work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.展开更多
A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were...A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were characterized by nitrogen adsorption-desorption,low and wide-angle X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),elemental mapping and energy-dispersive X-ray(EDX)methods.It was found that the particle size,electronic interactions,morphology,and textural properties of these catalysts as well as their catalytic activity in the reaction of H_(2) with O_(2) were affected by Co addition and different calcination temperatures.Also,the results showed that while the H_(2)O_(2) selectivity depends on Pd^(2+) species,the H_(2) conversion is related to Pd0 active sites.Among these catalysts,CoPd/KIT-6 calcined at 350℃(CoPd/KIT-350 catalyst)showed the best catalytic activity with 50%of H_(2)O_(2) selectivity and 51%conversion of H_(2).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
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
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 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.
基金support by the National Natural Science Foundation of China(U21A20306,U20A20152)Natural Science Foundation of Hebei Province(B2022202077).
文摘Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen source.The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 addition.The hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd NPs.This process helped to improve metal dispersion.The increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF catalyst.Furthermore,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction process.This work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.
基金the financial support(Research Council Grant)provided by Isfahan University of Technology(Iran).
文摘A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were characterized by nitrogen adsorption-desorption,low and wide-angle X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),elemental mapping and energy-dispersive X-ray(EDX)methods.It was found that the particle size,electronic interactions,morphology,and textural properties of these catalysts as well as their catalytic activity in the reaction of H_(2) with O_(2) were affected by Co addition and different calcination temperatures.Also,the results showed that while the H_(2)O_(2) selectivity depends on Pd^(2+) species,the H_(2) conversion is related to Pd0 active sites.Among these catalysts,CoPd/KIT-6 calcined at 350℃(CoPd/KIT-350 catalyst)showed the best catalytic activity with 50%of H_(2)O_(2) selectivity and 51%conversion of H_(2).
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 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.
