The preferential oxidation of CO(CO-PROX)reaction is a cost-effective method for eliminating trace amounts of CO from the fuel H2.Pt-based catalysts have been extensively studied for COPROX,with their activity influen...The preferential oxidation of CO(CO-PROX)reaction is a cost-effective method for eliminating trace amounts of CO from the fuel H2.Pt-based catalysts have been extensively studied for COPROX,with their activity influenced by the morphology of the support.Hydrothermal synthesis was employed to produce different morphologies ofγ-Al_(2)O_(3):flower-likeγ-Al_(2)O_(3)(f)exposing(110)crystal faces,sheet-likeγ-Al_(2)O_(3)(s)revealing(100)crystal faces,and rod-likeγ-Al_(2)O_(3)(r)displaying(111)crystal faces,followed by loading PtCo nanoparticles.The exposed crystal faces of the support impact the alloying degree of the PtCo nanoparticles,and an increase in the alloying degree correlates with enhanced catalyst reactivity.Pt_(3)Co intermetallic compounds were identified onγ-Al_(2)O_(3)(f)exposing(110)crystal faces,and PtCo/γ-Al_(2)O_(3)(f)showed high catalytic activity in the CO-PROX reaction,achieving 100%CO conversion across a broad temperature range of 50−225°C.In contrast,only partial alloying of PtCo was observed onγ-Al_(2)O_(3)(s).Furthermore,no alloying between Pt and Co occurred in PtCo/γ-Al_(2)O_(3)(r),resulting in a reaction rate at 50°C that was merely 11%of that of PtCo/γ-Al_(2)O_(3)(f).The formation of Pt3Co intermetallic compounds led to a more oxidized state of Pt,which significantly diminished the adsorption of CO on Pt and augmented the active oxygen species,thereby facilitating the selective oxidation of CO.展开更多
The palladium-catalyzed Suzuki-Miyaura cross-coupling(SMC)reaction has received worldwide attention as a powerful and convenient synthetic tool for the formation of biaryl compounds.However,these reactions are highly ...The palladium-catalyzed Suzuki-Miyaura cross-coupling(SMC)reaction has received worldwide attention as a powerful and convenient synthetic tool for the formation of biaryl compounds.However,these reactions are highly dependent on the activity and stable of catalysts.Herein,the support morphology-dependent catalytic performance of SMC reactions was investigated.The truncated hexagonal bipyramid(α-Fe_(2)O_(3)-O)and rod-shaped morphologies of alpha-Fe_(2)O_(3)(α-Fe_(2)O_(3)-R)were used as support to prepare PdCu nanoparticles(NPs)catalysts by NaBH_(4) reduction method.For PdCu/α-Fe_(2)O_(3)-R catalysts,the smaller size of PdCu NPs and more low coordination Pd sites leading to its superior catalytic performance for SMC reactions.Furthermore,it can be easily recycled through centrifugation and reused several times without obvious loss on its catalytic performance.Identical location transmission electron microscopy method was used to investigate the structural evolution of PdCu/α-Fe_(2)O_(3)-R catalysts.The results found that its structure almost unchanged during the catalytic reaction.展开更多
The role of water in CO oxidation was investigated on Pd/CeO2 with different morphologies(rods(R),cubes(C)and octahedrons(O)).Compared with the absence of water,CO oxidation activity increases 2 times in the presence ...The role of water in CO oxidation was investigated on Pd/CeO2 with different morphologies(rods(R),cubes(C)and octahedrons(O)).Compared with the absence of water,CO oxidation activity increases 2 times in the presence of water on Pd/CeO2-C;but a decrease is found on Pd/CeO2-R.Catalyst characterization reveals that Pd is mainly in the form of solid solution(PdxCe1-xO2-σ)on Pd/CeO2-R and a mixture of metal and PdxCe1-xO2-σsolid solution on Pd/CeO2-C.The strong interaction between Pd and CeO2-R results in the form of stable bidentate carbonates species;while the relatively weak interaction between Pd and CeO2-C leads to the produce of unstable monodentate carbonates species.The effects of water on CO oxidation activity closely relate with the Pd chemical state and the types of carbonates species.Water restrains CO adsorption on PdxCe1-xO2-σsolid solution,but it has negligent effects on metallic Pd species.In the presence of water,bidentate carbonates species remains stable but the decrease in the amount of monodentate carbonates species is observed.展开更多
Pidan or century egg, also known as preserved egg, is one of the most traditional and popular egg products in China. The crack detection of preserved eggshell is very important to guarantee its quality. In this study,...Pidan or century egg, also known as preserved egg, is one of the most traditional and popular egg products in China. The crack detection of preserved eggshell is very important to guarantee its quality. In this study, we develop an image algorithm for preserved eggshell＇s crack detection by using natural light and polarized image. Four features including crack length, crack state coefficient, maximum projection and angular point are extracted from the natural light image by morphology calculus algorithms. The support vector machines（SVM） model with radial basis kernel function is established using the four features with an accuracy of about 92%. The detection accuracy is improved to 94% by using a new characteristic parameter of crack length on polarization image. The Multi-information fusion analysis indicates the potential for cracks detection by a real-time synthesis imaging system.展开更多
基金supported by the National Natural Science Foundation of China(22376063,21976057)the Fund of the National Engineering Laboratory for Mobile Source Emission Control Technology(NELMS2020A05)Fundamental Research Funds for the Central Universities.
文摘The preferential oxidation of CO(CO-PROX)reaction is a cost-effective method for eliminating trace amounts of CO from the fuel H2.Pt-based catalysts have been extensively studied for COPROX,with their activity influenced by the morphology of the support.Hydrothermal synthesis was employed to produce different morphologies ofγ-Al_(2)O_(3):flower-likeγ-Al_(2)O_(3)(f)exposing(110)crystal faces,sheet-likeγ-Al_(2)O_(3)(s)revealing(100)crystal faces,and rod-likeγ-Al_(2)O_(3)(r)displaying(111)crystal faces,followed by loading PtCo nanoparticles.The exposed crystal faces of the support impact the alloying degree of the PtCo nanoparticles,and an increase in the alloying degree correlates with enhanced catalyst reactivity.Pt_(3)Co intermetallic compounds were identified onγ-Al_(2)O_(3)(f)exposing(110)crystal faces,and PtCo/γ-Al_(2)O_(3)(f)showed high catalytic activity in the CO-PROX reaction,achieving 100%CO conversion across a broad temperature range of 50−225°C.In contrast,only partial alloying of PtCo was observed onγ-Al_(2)O_(3)(s).Furthermore,no alloying between Pt and Co occurred in PtCo/γ-Al_(2)O_(3)(r),resulting in a reaction rate at 50°C that was merely 11%of that of PtCo/γ-Al_(2)O_(3)(f).The formation of Pt3Co intermetallic compounds led to a more oxidized state of Pt,which significantly diminished the adsorption of CO on Pt and augmented the active oxygen species,thereby facilitating the selective oxidation of CO.
基金financial support provided by the National Natural Science Foundation of China(grant No.22072164)the Research Fund of Shenyang National Laboratory for Materials Science.
文摘The palladium-catalyzed Suzuki-Miyaura cross-coupling(SMC)reaction has received worldwide attention as a powerful and convenient synthetic tool for the formation of biaryl compounds.However,these reactions are highly dependent on the activity and stable of catalysts.Herein,the support morphology-dependent catalytic performance of SMC reactions was investigated.The truncated hexagonal bipyramid(α-Fe_(2)O_(3)-O)and rod-shaped morphologies of alpha-Fe_(2)O_(3)(α-Fe_(2)O_(3)-R)were used as support to prepare PdCu nanoparticles(NPs)catalysts by NaBH_(4) reduction method.For PdCu/α-Fe_(2)O_(3)-R catalysts,the smaller size of PdCu NPs and more low coordination Pd sites leading to its superior catalytic performance for SMC reactions.Furthermore,it can be easily recycled through centrifugation and reused several times without obvious loss on its catalytic performance.Identical location transmission electron microscopy method was used to investigate the structural evolution of PdCu/α-Fe_(2)O_(3)-R catalysts.The results found that its structure almost unchanged during the catalytic reaction.
基金Project supported financially by the National Key Research and Development Program of China(2016YFC0204300)the National Natural Science Foundation of China(21976057,21922602)the Shanghai“Pujiang”Program(18PJD011)。
文摘The role of water in CO oxidation was investigated on Pd/CeO2 with different morphologies(rods(R),cubes(C)and octahedrons(O)).Compared with the absence of water,CO oxidation activity increases 2 times in the presence of water on Pd/CeO2-C;but a decrease is found on Pd/CeO2-R.Catalyst characterization reveals that Pd is mainly in the form of solid solution(PdxCe1-xO2-σ)on Pd/CeO2-R and a mixture of metal and PdxCe1-xO2-σsolid solution on Pd/CeO2-C.The strong interaction between Pd and CeO2-R results in the form of stable bidentate carbonates species;while the relatively weak interaction between Pd and CeO2-C leads to the produce of unstable monodentate carbonates species.The effects of water on CO oxidation activity closely relate with the Pd chemical state and the types of carbonates species.Water restrains CO adsorption on PdxCe1-xO2-σsolid solution,but it has negligent effects on metallic Pd species.In the presence of water,bidentate carbonates species remains stable but the decrease in the amount of monodentate carbonates species is observed.
基金Supported by the Fundamental Funds for Central University(2662014BQ062)
文摘Pidan or century egg, also known as preserved egg, is one of the most traditional and popular egg products in China. The crack detection of preserved eggshell is very important to guarantee its quality. In this study, we develop an image algorithm for preserved eggshell＇s crack detection by using natural light and polarized image. Four features including crack length, crack state coefficient, maximum projection and angular point are extracted from the natural light image by morphology calculus algorithms. The support vector machines（SVM） model with radial basis kernel function is established using the four features with an accuracy of about 92%. The detection accuracy is improved to 94% by using a new characteristic parameter of crack length on polarization image. The Multi-information fusion analysis indicates the potential for cracks detection by a real-time synthesis imaging system.
