We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effec...We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effect of combining MWCNTs with β-CD led to a remarkable increase in the performance of the MWCNTs-g-CD for the catalytic oxidation of cinnamaldehyde, which exhibited 95% cinnamaldehyde conversion and 85% selectivity to natural benzaldehyde with a short reaction time of 10 rain. The MWCNTs-g-CD also exhibited outstanding recyclability with good stability, showing no discernible decrease in their catalytic activity over five reaction cycles.展开更多
A simple approach for the condensation of benzaldehyde with ethylene glycol was adopted without employing any catalyst. The study reveals that factors including temperature, molar ratio of reactants, and the water rem...A simple approach for the condensation of benzaldehyde with ethylene glycol was adopted without employing any catalyst. The study reveals that factors including temperature, molar ratio of reactants, and the water removal significantly influence the conversion ratio of benzaldehyde. The results indicate that the use of optimal reaction conditions such as temperature and water removing exhibits more pronounced effects on the conversion ratio of benzaldehyde compared with the use of catalysts. In a word, a green and simple method for the condensation of aldehyde and menthandiol has been devised and investigated.展开更多
A series of Mn/CeO2-Al2O3 and K/CeO2-Al2O3 catalysts for hydrogenation of benzoic acid to benzaldehyde were prepared to in- vestigate the effect of Mn, K addition on CeO2-Al2O3 catalyst. X-ray diffraction (XRD) and H2...A series of Mn/CeO2-Al2O3 and K/CeO2-Al2O3 catalysts for hydrogenation of benzoic acid to benzaldehyde were prepared to in- vestigate the effect of Mn, K addition on CeO2-Al2O3 catalyst. X-ray diffraction (XRD) and H2-temperature-programmed reduction (H2-TPR) results suggested that the interaction between CeO2 and MnOx enhanced the reducibility of catalysts and therefore benzoic acid conversion. The addition of K increased the number of basic number on the catalyst which leads to a high selectivity to benzaldehyde, but excessive addition imposed negative effects on the catalyst performance. A Mn-K/CeO2-Al2O3 catalyst was developed and investigated in the reaction. The simultaneous addition of Mn and K enhanced not only the catalytic activity but also the capacity to resist the coke formation over catalyst.展开更多
Effects of reaction parameter on yield of benzaldehyde produced from toluene oxidization using hydrogen peroxide in subcritical water are investigated. The experimental results show that if the molar ratio of hydrogen...Effects of reaction parameter on yield of benzaldehyde produced from toluene oxidization using hydrogen peroxide in subcritical water are investigated. The experimental results show that if the molar ratio of hydrogen peroxide to toluene is controlled within a reasonable range, the by-products may be neglected. The optimum technology of toluene oxidization to benzaldehyde is reaction time 60 min, reaction temperature 350℃, molar ratio of hydrogen peroxide to toluene 3.5. The yield of benzaldehyde can reach 17.2 % under the optimum condition. Research results of chemical reaction kinetics show that the consecutive reaction consists of two first-order reaction, and activation energy of these two reactions are 89 kJ·mol^-1 and 76 kJ·mol^-1 respectively,展开更多
Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via fun...Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via functionalization of carbon nanotubes （CNTs）, which are used as the support of Pd. With the original CNTs, the selectivity of benzyl alcohol is 88% at a 100% conversion of benzaldehyde. With introduction of oxygen-containing groups onto CNTs, it drops to 27%. In contrast, doping CNTs with N atoms, the selectivity reaches 96% under the same reaction conditions. The kinetic study shows that hydrogenation of benzyl alcohol is significantly suppressed, which can be attributed to weakened adsorption of benzyl alcohol. This is most likely related to the modified electronic structure of Pd species via interaction with functionalized CNTs, as shown by XPS characterization.展开更多
Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic re...Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V+Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No. 4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V_2O_5 lattice of the K-doped catalyst and a better interracial contact between the particles.展开更多
A series of hexadecylphosphate acid(HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/wate...A series of hexadecylphosphate acid(HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/water with the catalysts as stabilizers. With the HDPA-Fe2 O3/Al2 O3 as the basic catalyst, a series of transition metals, such as Mn, Co, Ni, Cu, Cr, Mo, V, and Ti, was respectively doped to the basic catalyst to modify the performance of the catalytic system, in expectation of influencing the mobility of the lattice oxygen species in the oxide catalysts. Under normally working conditions of the catalytic system, the nanoparticles of catalysts located themselves at the interface between the oil and water phases, constituting the Pickering emulsion. Both the doped iron oxide and its surface adsorbed hexadecylphosphate molecules were essential to the catalytic system for excellent performances with high toluene conversions as well as the exclusive selectivity to benzaldehyde. Under optimal conditions, ~83% of toluene conversion and >99% selectivity to benzaldehyde were obtained, using molecular oxygen as oxidant and HDPA-(Fe2 O3-Ni O)/Al2 O3 as the catalyst. This process is green and low cost to produce high quality benzaldehyde from O2 oxidation of toluene.展开更多
The effect of different concentrations of benzaldehyde on the electrodeposition of Ni–W alloy coatings on a mild steel substrate from a citrate electrolyte was investigated in this study. The electrolytic alkaline ba...The effect of different concentrations of benzaldehyde on the electrodeposition of Ni–W alloy coatings on a mild steel substrate from a citrate electrolyte was investigated in this study. The electrolytic alkaline bath(p H 8.0) contained stoichiometric amounts of nickel sulfate, sodium tungstate, and trisodium citrate as precursors. The corrosion resistance of the Ni–W-alloy-coated specimens in 0.2 mol/L H2SO4 was studied using various electrochemical techniques. Tafel polarization studies reveal that the alloy coatings obtained from the bath containing 50 ppm benzaldehyde exhibit a protection efficiency of 95.33%. The corrosion rate also decreases by 21.5 times compared with that of the blank. A higher charge-transfer resistance of 1159.40 ?·cm2 and a lower double-layer capacitance of 29.4 μF·cm-2 further confirm the better corrosion resistance of the alloy coating. X-ray diffraction studies reveal that the deposits on the mild steel surface are consisted of nanocrystals. A lower surface roughness value(Rmax) of the deposits is confirmed by atomic force microscopy.展开更多
In this study, liquid-phase aerobic oxidation of toluene catalyzed by Mn–Mo oxide was conducted in a 1.0 L batch reactor. The macroscopic kinetics of toluene consumption and benzaldehyde generation at 413–443 K were...In this study, liquid-phase aerobic oxidation of toluene catalyzed by Mn–Mo oxide was conducted in a 1.0 L batch reactor. The macroscopic kinetics of toluene consumption and benzaldehyde generation at 413–443 K were obtained from a combination of experimental observation and hypothetical models. The results clearly showed that both the oxidation rate of toluene and generation rate of the aromatic product were proportional to the concentration of the substrate, the partial pressure of oxygen and the surface area of the catalyst. The energy barrier of toluene oxidation to benzyl alcohol was the highest(≈ 81 kJ mol^(-1)), while that of benzyl alcohol oxidation to benzaldehyde was the lowest(≈ 57 kJ mol^(-1)). Moreover, the activation energy of further oxidation of benzaldehyde in an acetic acid solvent was only slightly lower(≈ 1.9 kJ mol^(-1)) than that of toluene oxidation. Significantly, the transformation of benzyl alcohol indeed contributed to the generation of benzaldehyde and this step conformed to a first-order parallel-consecutive model. Increased reaction temperature and residence time favored the transformation of benzyl alcohol to benzaldehyde. In addition, doping with molybdenum at Mn/Mo = 3/1 enhanced the catalytic performance of the heterogeneous catalyst and was attributed to the presence of a synergetic effect between different metal cations. Regarding the microscopic kinetics, the LH-OS-ND mechanism(Langmuir–Hinshelwood adsorption of reagents on the same type of active sites and non-dissociative adsorption of oxygen) was verified as responsible for the heterogeneous oxidation of toluene. Oxygen and benzaldehyde were weakly adsorbed(Δ H_(ads,Oxy) ≈^(-1)5 kJ mol^(-1), Δ H _(ads)0,Bald) ≈-30 kJ mol^(-1)), but showed strong mobility(Δ S_(ads,Oxy) ≈-22 J mol^(-1) K^(-1)), Δ S_(ads,Bald) ≈-39 J mol^(-1) K^(-1)). The fundamental intrinsic rates were deduced based on the LH-OS-ND mechanism and showed great consistency with the macroscopic results.展开更多
A facile and efficient procedure has been developed systematically for the oxidative cleavage of cinna-maldehyde to benzaldehyde by sodium hypochlorite with water as the only solvent in the presence of β-cyclodextrin...A facile and efficient procedure has been developed systematically for the oxidative cleavage of cinna-maldehyde to benzaldehyde by sodium hypochlorite with water as the only solvent in the presence of β-cyclodextrin （abbreviated as β-CD）. Different factors influencing cinnamaldehyde oxidation e.g. reaction temperature, the amount of catalyst and oxidant, have been investigated. The yield of benzaldehyde reaches 76% under the optimum conditions （333 K, 4 h, molar ratio of cinnamaldehyde to β-CD is 1：1）. Furthermore, a feasible reaction mecha-nism including the formation of benzaldehyde and the two main byproducts （phenylacetaldehyde and epoxide of cinnamaldehyde） has been proposed.展开更多
In this work we used CdS NWs(nanowires)with vanadium carbide(VC)attached via facile electrostatic self‐assembly and calcination method.The results showed that compared to pristine CdS NWs,the photocatalytic activity ...In this work we used CdS NWs(nanowires)with vanadium carbide(VC)attached via facile electrostatic self‐assembly and calcination method.The results showed that compared to pristine CdS NWs,the photocatalytic activity of CdS NWs loaded with the particular amount of VC was dramatically enhanced.Among them,the VC/CS‐15 indicated the highest enhancement for simultaneous production of H2 with selective oxidation of benzyl alcohol(BO)into benzaldehyde(BD).The highest hydrogen evolution rate of 20.5 mmol g^(-1)h^(-1)was obtained with more than 99%selectivity for BD production under visible light(λ˃420 nm)irradiation for 2 h,which was almost 661 times higher than the pristine CdS NWs.This enhancement of photocatalytic activity is due to the VC,which provides a favorable attraction for BO by lowering the zeta potential,along with the active site for hydrogen production,and retard the recombination of electron‐hole pairs by increasing the conductivity of the photocatalyst.Moreover,the apparent quantum efficiency(AQE)of VC/CS‐15 for BD and H_(2)production at monochromatic 420 nm is about 7.5%.At the end of the hydrogen evolution test,the selective oxidation with more than 99%selectivity was obtained.It hopes this work will prove its future significance and move scientific community toward a more economical way for achieving the commercialization of H_(2) by photocatalysis.展开更多
The completely selective oxidation of toluene to benzaldehyde with dioxygen,without the need touse H_(2)O_(2),halogens,or any radical initiators,is a reaction long desired but never previously successful.Here,we demon...The completely selective oxidation of toluene to benzaldehyde with dioxygen,without the need touse H_(2)O_(2),halogens,or any radical initiators,is a reaction long desired but never previously successful.Here,we demonstrate the enzyme‐like mechanism of the reaction over hexadecylphosphateacid(HDPA)‐bonded nano‐oxides,which appear to interact with toluene through specific recognition.The active sites of the catalyst are related to the ability of HDPA to change its bonding to theoxides between monodentate and bidentate during the reaction cycle.This greatly enhances themobility of the crystal oxygen or the reactivity of the catalyst,specifically in toluene transformations.The catalytic cycle of the catalyst is similar to that of methane monooxygenase.In thepresence of catalyst and through O_(2)oxidation,the conversion of toluene to benzaldehyde is initiatedat 70°C.We envision that this novel mechanism reveals alternatives for an attractive route to designhigh‐performance catalysts with bioinspired structures.展开更多
In this paper the two effluents from PBA (3- phenoxy -benzaldehyde) productionprocess were treated by polymeric adsorbent CHA-lll. PBA or PBC(3-phenoxybenzoic acid) was recovered from the wastewater in the process of ...In this paper the two effluents from PBA (3- phenoxy -benzaldehyde) productionprocess were treated by polymeric adsorbent CHA-lll. PBA or PBC(3-phenoxybenzoic acid) was recovered from the wastewater in the process of neutralization. As asecondary treatment method, adsorption with CHA-lll showed better efficency thanPhotocatalytic decomposition and solvent extraction. The optimal technologicalparameters were: adsorption: current velocity: 2.0 BV/hr(bed volume per hour), roomtemperature, desorption: current velocity:10 BV/hr 80℃8% sodium hydroxideaqueous solutions. In conclusion, 90.9% COD in the neutralizing wastewater and98. 4% COD in the hydrolysis wastewater are removed successfully.展开更多
One of the central tasks in the field of heterogeneous catalysis is to establish structure‐function relationships for these catalysts,especially for precious metals dispersed on the sub‐nanometer scale.Here,we repor...One of the central tasks in the field of heterogeneous catalysis is to establish structure‐function relationships for these catalysts,especially for precious metals dispersed on the sub‐nanometer scale.Here,we report the preparation of MgAl2O4‐supported Pt nanoparticles,amorphous aggregates and single atoms,and evaluate their ability to catalyze the hydrogenation of benzaldehyde.The Pt species were characterized by N2adsorption,X‐ray diffraction(XRD),aberration‐corrected transmission electron microscopy(ACTEM),CO chemisorption and in situ Fourier transform infrared spectroscopy of the chemisorbed CO,as well as by inductively coupled plasma atomic emission spectroscopy.They existed as isolated or neighboring single atoms on the MgAl2O4support,and formed amorphous Pt aggregates and then nanocrystallites with increased Pt loading.On the MgAl2O4support,single Pt atoms were highly active in the selective catalytic hydrogenation of benzaldehyde to benzyl alcohol.The terrace atoms of the Pt particles were more active but less selective;this was presumably due to their ability to form bridged carbonyl adsorbates.The MgAl2O4‐supported single‐atom Pt catalyst is a novel catalyst with a high precious atom efficiency and excellent catalytic hydrogenation ability and selectivity.展开更多
In this paper, a new catalysts system V-Cs-Cu-TI was studied in the gas phase selective oxidation for p-tert butyl toluene to p-tert benzaldehyde. The catalyst system was prepared by impregnation method. The results o...In this paper, a new catalysts system V-Cs-Cu-TI was studied in the gas phase selective oxidation for p-tert butyl toluene to p-tert benzaldehyde. The catalyst system was prepared by impregnation method. The results obtained are optimum value and have good advantages in environmental protection.展开更多
Functionalized benzylic zinc halides reacted with benzaldehydes in the presence of Lewis acid Me3SiCl giving high yields of trans-stilbenes under the catalysis of Co(PPh3)3Cl.
This paper has studied the recycling of the oxidation mediator Mn(Ⅲ)/Mn(Ⅱ) and sulfuric acid solution in process of indirect electrosynthesis of benzaldehyde. Experimental resalts show that mis recycling may be real...This paper has studied the recycling of the oxidation mediator Mn(Ⅲ)/Mn(Ⅱ) and sulfuric acid solution in process of indirect electrosynthesis of benzaldehyde. Experimental resalts show that mis recycling may be realized When electrolysis and synthetic reaction are carried out in the same concentration of 60% H2SO4 separately, then there will be no waste discharged, energy consumption will be decreased and almost no current efficiency will be lossed during recycling process. The optimun current efficiency is 76%, yield of benzaldehyde is 64%.展开更多
基金supported by the National Natural Science Foundation of China (21376279, 21276102, 21425627)Guangdong Technology Research Center for Synthesis and Separation of Thermosensitive Chemicals (2015B090903061)+1 种基金the Fundamental Research Funds for the Central Universities (14lgpy28)Guangzhou Science and Technology Plan Projects (2014J4100125)~~
文摘We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effect of combining MWCNTs with β-CD led to a remarkable increase in the performance of the MWCNTs-g-CD for the catalytic oxidation of cinnamaldehyde, which exhibited 95% cinnamaldehyde conversion and 85% selectivity to natural benzaldehyde with a short reaction time of 10 rain. The MWCNTs-g-CD also exhibited outstanding recyclability with good stability, showing no discernible decrease in their catalytic activity over five reaction cycles.
基金Supported by the National Natural Science Foundation of China(No.51073023)the Co-building Special Profect of Beijing Municipal Education Commission(China)
文摘A simple approach for the condensation of benzaldehyde with ethylene glycol was adopted without employing any catalyst. The study reveals that factors including temperature, molar ratio of reactants, and the water removal significantly influence the conversion ratio of benzaldehyde. The results indicate that the use of optimal reaction conditions such as temperature and water removing exhibits more pronounced effects on the conversion ratio of benzaldehyde compared with the use of catalysts. In a word, a green and simple method for the condensation of aldehyde and menthandiol has been devised and investigated.
基金Project supported by the Science and Technology Department of Zhejiang Province,China (2007C21103)
文摘A series of Mn/CeO2-Al2O3 and K/CeO2-Al2O3 catalysts for hydrogenation of benzoic acid to benzaldehyde were prepared to in- vestigate the effect of Mn, K addition on CeO2-Al2O3 catalyst. X-ray diffraction (XRD) and H2-temperature-programmed reduction (H2-TPR) results suggested that the interaction between CeO2 and MnOx enhanced the reducibility of catalysts and therefore benzoic acid conversion. The addition of K increased the number of basic number on the catalyst which leads to a high selectivity to benzaldehyde, but excessive addition imposed negative effects on the catalyst performance. A Mn-K/CeO2-Al2O3 catalyst was developed and investigated in the reaction. The simultaneous addition of Mn and K enhanced not only the catalytic activity but also the capacity to resist the coke formation over catalyst.
文摘Effects of reaction parameter on yield of benzaldehyde produced from toluene oxidization using hydrogen peroxide in subcritical water are investigated. The experimental results show that if the molar ratio of hydrogen peroxide to toluene is controlled within a reasonable range, the by-products may be neglected. The optimum technology of toluene oxidization to benzaldehyde is reaction time 60 min, reaction temperature 350℃, molar ratio of hydrogen peroxide to toluene 3.5. The yield of benzaldehyde can reach 17.2 % under the optimum condition. Research results of chemical reaction kinetics show that the consecutive reaction consists of two first-order reaction, and activation energy of these two reactions are 89 kJ·mol^-1 and 76 kJ·mol^-1 respectively,
基金supported by the National Science Foundation of China (No. 21006129,11079005 and 21033009)the Ministry of Science and Technology of China (No. 2011CBA00503)
文摘Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via functionalization of carbon nanotubes （CNTs）, which are used as the support of Pd. With the original CNTs, the selectivity of benzyl alcohol is 88% at a 100% conversion of benzaldehyde. With introduction of oxygen-containing groups onto CNTs, it drops to 27%. In contrast, doping CNTs with N atoms, the selectivity reaches 96% under the same reaction conditions. The kinetic study shows that hydrogenation of benzyl alcohol is significantly suppressed, which can be attributed to weakened adsorption of benzyl alcohol. This is most likely related to the modified electronic structure of Pd species via interaction with functionalized CNTs, as shown by XPS characterization.
文摘Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V+Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No. 4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V_2O_5 lattice of the K-doped catalyst and a better interracial contact between the particles.
基金supported by the National Natural Science Foundation of China(91434101,91745108)the Ministry of Science and Technology of the People’s Republic of China(2017YFB0702900)~~
文摘A series of hexadecylphosphate acid(HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/water with the catalysts as stabilizers. With the HDPA-Fe2 O3/Al2 O3 as the basic catalyst, a series of transition metals, such as Mn, Co, Ni, Cu, Cr, Mo, V, and Ti, was respectively doped to the basic catalyst to modify the performance of the catalytic system, in expectation of influencing the mobility of the lattice oxygen species in the oxide catalysts. Under normally working conditions of the catalytic system, the nanoparticles of catalysts located themselves at the interface between the oil and water phases, constituting the Pickering emulsion. Both the doped iron oxide and its surface adsorbed hexadecylphosphate molecules were essential to the catalytic system for excellent performances with high toluene conversions as well as the exclusive selectivity to benzaldehyde. Under optimal conditions, ~83% of toluene conversion and >99% selectivity to benzaldehyde were obtained, using molecular oxygen as oxidant and HDPA-(Fe2 O3-Ni O)/Al2 O3 as the catalyst. This process is green and low cost to produce high quality benzaldehyde from O2 oxidation of toluene.
文摘The effect of different concentrations of benzaldehyde on the electrodeposition of Ni–W alloy coatings on a mild steel substrate from a citrate electrolyte was investigated in this study. The electrolytic alkaline bath(p H 8.0) contained stoichiometric amounts of nickel sulfate, sodium tungstate, and trisodium citrate as precursors. The corrosion resistance of the Ni–W-alloy-coated specimens in 0.2 mol/L H2SO4 was studied using various electrochemical techniques. Tafel polarization studies reveal that the alloy coatings obtained from the bath containing 50 ppm benzaldehyde exhibit a protection efficiency of 95.33%. The corrosion rate also decreases by 21.5 times compared with that of the blank. A higher charge-transfer resistance of 1159.40 ?·cm2 and a lower double-layer capacitance of 29.4 μF·cm-2 further confirm the better corrosion resistance of the alloy coating. X-ray diffraction studies reveal that the deposits on the mild steel surface are consisted of nanocrystals. A lower surface roughness value(Rmax) of the deposits is confirmed by atomic force microscopy.
基金supported by the National Natural Science Foundation of China (No. 21376163)
文摘In this study, liquid-phase aerobic oxidation of toluene catalyzed by Mn–Mo oxide was conducted in a 1.0 L batch reactor. The macroscopic kinetics of toluene consumption and benzaldehyde generation at 413–443 K were obtained from a combination of experimental observation and hypothetical models. The results clearly showed that both the oxidation rate of toluene and generation rate of the aromatic product were proportional to the concentration of the substrate, the partial pressure of oxygen and the surface area of the catalyst. The energy barrier of toluene oxidation to benzyl alcohol was the highest(≈ 81 kJ mol^(-1)), while that of benzyl alcohol oxidation to benzaldehyde was the lowest(≈ 57 kJ mol^(-1)). Moreover, the activation energy of further oxidation of benzaldehyde in an acetic acid solvent was only slightly lower(≈ 1.9 kJ mol^(-1)) than that of toluene oxidation. Significantly, the transformation of benzyl alcohol indeed contributed to the generation of benzaldehyde and this step conformed to a first-order parallel-consecutive model. Increased reaction temperature and residence time favored the transformation of benzyl alcohol to benzaldehyde. In addition, doping with molybdenum at Mn/Mo = 3/1 enhanced the catalytic performance of the heterogeneous catalyst and was attributed to the presence of a synergetic effect between different metal cations. Regarding the microscopic kinetics, the LH-OS-ND mechanism(Langmuir–Hinshelwood adsorption of reagents on the same type of active sites and non-dissociative adsorption of oxygen) was verified as responsible for the heterogeneous oxidation of toluene. Oxygen and benzaldehyde were weakly adsorbed(Δ H_(ads,Oxy) ≈^(-1)5 kJ mol^(-1), Δ H _(ads)0,Bald) ≈-30 kJ mol^(-1)), but showed strong mobility(Δ S_(ads,Oxy) ≈-22 J mol^(-1) K^(-1)), Δ S_(ads,Bald) ≈-39 J mol^(-1) K^(-1)). The fundamental intrinsic rates were deduced based on the LH-OS-ND mechanism and showed great consistency with the macroscopic results.
基金Supported by the National＇Natural Science Foundation of China （21036009, 21176268）, the Higher-level Talent Project tor Guangdong Provincial Universities and the Fundamental.Research Funds for the Central Universities.
文摘A facile and efficient procedure has been developed systematically for the oxidative cleavage of cinna-maldehyde to benzaldehyde by sodium hypochlorite with water as the only solvent in the presence of β-cyclodextrin （abbreviated as β-CD）. Different factors influencing cinnamaldehyde oxidation e.g. reaction temperature, the amount of catalyst and oxidant, have been investigated. The yield of benzaldehyde reaches 76% under the optimum conditions （333 K, 4 h, molar ratio of cinnamaldehyde to β-CD is 1：1）. Furthermore, a feasible reaction mecha-nism including the formation of benzaldehyde and the two main byproducts （phenylacetaldehyde and epoxide of cinnamaldehyde） has been proposed.
文摘In this work we used CdS NWs(nanowires)with vanadium carbide(VC)attached via facile electrostatic self‐assembly and calcination method.The results showed that compared to pristine CdS NWs,the photocatalytic activity of CdS NWs loaded with the particular amount of VC was dramatically enhanced.Among them,the VC/CS‐15 indicated the highest enhancement for simultaneous production of H2 with selective oxidation of benzyl alcohol(BO)into benzaldehyde(BD).The highest hydrogen evolution rate of 20.5 mmol g^(-1)h^(-1)was obtained with more than 99%selectivity for BD production under visible light(λ˃420 nm)irradiation for 2 h,which was almost 661 times higher than the pristine CdS NWs.This enhancement of photocatalytic activity is due to the VC,which provides a favorable attraction for BO by lowering the zeta potential,along with the active site for hydrogen production,and retard the recombination of electron‐hole pairs by increasing the conductivity of the photocatalyst.Moreover,the apparent quantum efficiency(AQE)of VC/CS‐15 for BD and H_(2)production at monochromatic 420 nm is about 7.5%.At the end of the hydrogen evolution test,the selective oxidation with more than 99%selectivity was obtained.It hopes this work will prove its future significance and move scientific community toward a more economical way for achieving the commercialization of H_(2) by photocatalysis.
文摘The completely selective oxidation of toluene to benzaldehyde with dioxygen,without the need touse H_(2)O_(2),halogens,or any radical initiators,is a reaction long desired but never previously successful.Here,we demonstrate the enzyme‐like mechanism of the reaction over hexadecylphosphateacid(HDPA)‐bonded nano‐oxides,which appear to interact with toluene through specific recognition.The active sites of the catalyst are related to the ability of HDPA to change its bonding to theoxides between monodentate and bidentate during the reaction cycle.This greatly enhances themobility of the crystal oxygen or the reactivity of the catalyst,specifically in toluene transformations.The catalytic cycle of the catalyst is similar to that of methane monooxygenase.In thepresence of catalyst and through O_(2)oxidation,the conversion of toluene to benzaldehyde is initiatedat 70°C.We envision that this novel mechanism reveals alternatives for an attractive route to designhigh‐performance catalysts with bioinspired structures.
文摘In this paper the two effluents from PBA (3- phenoxy -benzaldehyde) productionprocess were treated by polymeric adsorbent CHA-lll. PBA or PBC(3-phenoxybenzoic acid) was recovered from the wastewater in the process of neutralization. As asecondary treatment method, adsorption with CHA-lll showed better efficency thanPhotocatalytic decomposition and solvent extraction. The optimal technologicalparameters were: adsorption: current velocity: 2.0 BV/hr(bed volume per hour), roomtemperature, desorption: current velocity:10 BV/hr 80℃8% sodium hydroxideaqueous solutions. In conclusion, 90.9% COD in the neutralizing wastewater and98. 4% COD in the hydrolysis wastewater are removed successfully.
基金supported by the National Natural Science Foundation of China(21403213,21673226,21376236,U1462121)the"Hundred Talents Programme"of the Chinese Academy of Sciences+3 种基金the"Strategic Priority Research Program"of the Chinese Academy of Sciences(XDB17020100)National Key R&D Program of China(2016YFA0202801)Department of Science and Technology of Liaoning province under contract of 2015020086-101the Natural Science Foundation of Hunan Province(2016JJ2128)~~
文摘One of the central tasks in the field of heterogeneous catalysis is to establish structure‐function relationships for these catalysts,especially for precious metals dispersed on the sub‐nanometer scale.Here,we report the preparation of MgAl2O4‐supported Pt nanoparticles,amorphous aggregates and single atoms,and evaluate their ability to catalyze the hydrogenation of benzaldehyde.The Pt species were characterized by N2adsorption,X‐ray diffraction(XRD),aberration‐corrected transmission electron microscopy(ACTEM),CO chemisorption and in situ Fourier transform infrared spectroscopy of the chemisorbed CO,as well as by inductively coupled plasma atomic emission spectroscopy.They existed as isolated or neighboring single atoms on the MgAl2O4support,and formed amorphous Pt aggregates and then nanocrystallites with increased Pt loading.On the MgAl2O4support,single Pt atoms were highly active in the selective catalytic hydrogenation of benzaldehyde to benzyl alcohol.The terrace atoms of the Pt particles were more active but less selective;this was presumably due to their ability to form bridged carbonyl adsorbates.The MgAl2O4‐supported single‐atom Pt catalyst is a novel catalyst with a high precious atom efficiency and excellent catalytic hydrogenation ability and selectivity.
文摘In this paper, a new catalysts system V-Cs-Cu-TI was studied in the gas phase selective oxidation for p-tert butyl toluene to p-tert benzaldehyde. The catalyst system was prepared by impregnation method. The results obtained are optimum value and have good advantages in environmental protection.
基金This work was supported by the National Natural Science Foundation of China and the Northwest Normal University Science and Technology Devolopment Foundation of China.
文摘Functionalized benzylic zinc halides reacted with benzaldehydes in the presence of Lewis acid Me3SiCl giving high yields of trans-stilbenes under the catalysis of Co(PPh3)3Cl.
文摘This paper has studied the recycling of the oxidation mediator Mn(Ⅲ)/Mn(Ⅱ) and sulfuric acid solution in process of indirect electrosynthesis of benzaldehyde. Experimental resalts show that mis recycling may be realized When electrolysis and synthetic reaction are carried out in the same concentration of 60% H2SO4 separately, then there will be no waste discharged, energy consumption will be decreased and almost no current efficiency will be lossed during recycling process. The optimun current efficiency is 76%, yield of benzaldehyde is 64%.
