The selective hydrogenation ofα,β-unsaturated aldehydes/ketones enables precise control over product structures and properties by regulating hydrogen transport pathways and bond cleavage sequences to selectively red...The selective hydrogenation ofα,β-unsaturated aldehydes/ketones enables precise control over product structures and properties by regulating hydrogen transport pathways and bond cleavage sequences to selectively reduce C=C or C=O bonds while preserving other functional groups within the molecule.This approach serves as a critical strategy for the directional synthesis of high-value molecules.However,achieving such selectivity remains challenging due to the thermodynamic equilibrium and kinetic competition between C=O and C=C bonds inα,β-unsaturated systems.Consequently,constructing precisely targeted catalytic systems is essential to overcome these limitations,offering both fundamental scientific significance and industrial application potential.Metal-organic frameworks(MOFs)and their derivatives have emerged as innovative platforms for designing such systems,owing to their programmable topology,tunable pore microenvironments,spatially controllable active sites,and modifiable electronic structures.This review systematically summarizes the research progress of MOF-based catalysts for selec-tive hydrogenation ofα,β-unsaturated aldehydes/ketones in the last decade,with emphasis on the design strategy,conformational relationship,and catalytic mechanism,aiming to provide new ideas for the design of targeted catalyt-ic systems for the selective hydrogenation ofα,β-unsaturated aldehydes/ketones.展开更多
The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts c...The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts contained Pd species in mixed valence states,with high valence Pd at the metal‑support interface and zero valence Pd at the metal surface.While the strong coordination of triphenylphosphine(PPh3)to Pd0 on the Pd surface prevents the adsorption of halogenated nitroaromatics and thus dehalogenation,the coordination of sodium metavanadate(NaVO3)to high‑valence Pd sites at the interface helps to activate H2 in a heterolytic pathway for the selective hydrogenation of nitro‑groups.The excellent catalytic performance of the interfacial active sites enables the selective hydrogenation of a wide range of halogenated nitroaromatics.展开更多
Cu/ZnO-based catalysts are widely employed for methanol synthesis via CO_(2) hydrogenation.The preparation procedure is sensitive to the particle size and interfacial structure,which are considered as potential active...Cu/ZnO-based catalysts are widely employed for methanol synthesis via CO_(2) hydrogenation.The preparation procedure is sensitive to the particle size and interfacial structure,which are considered as potential active centers influencing the rate of both methanol and CO formation.The particle size and the interaction between Cu and the support materials are influenced by the coprecipitation conditions,let alone that the mechanistic divergence remains unclear.In this work,a series of Cu/ZnO/ZrO_(2) catalysts were prepared via co-precipitation at different pH value and systematically characterized.The structure has been correlated with kinetic results to establish the structure-performance relationship.Kinetic analysis demonstrates that methanol synthesis follows a single-site Langmuir-Hinshelwood(L-H)mechanism,i.e.,Cu serves as the active site where CO_(2) and H_(2) competitively adsorb and react to form methanol.In contrast,CO formation proceeds via a dual-site L-H mechanism,where CO_(2) adsorbs onto ZnO and H_(2) onto Cu,with the reaction occurring at the Cu/ZnO interface.Therefore,for the direct formation of methanol,solely reducing the particle size of Cu would not be beneficial.展开更多
The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques inc...The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.展开更多
Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Co...Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts.展开更多
Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as...Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as the strongly enhanced synergistic interactions between Pt and Co atoms,the obtained Pt-on-Co/C400 catalysts exhib-ited excellent catalytic activity toward the hydrolysis of ammonia borane with an extremely high turnover frequency(TOF)value of 3022 min^(-1)at 303 K.Durability test indicated that the obtained Pt-on-Co/C400 catalysts possessed high catalytic stability,and there were no changes in the catalyst structures and catalytic activities after 10 cycles.展开更多
Highly active and stable nickel catalyst for dehydrogenation of methane and hydrogenation of benzene is prepared from a precursor with hydrotalcite-like anionic clam structure by coprecipitation. The nickel particles ...Highly active and stable nickel catalyst for dehydrogenation of methane and hydrogenation of benzene is prepared from a precursor with hydrotalcite-like anionic clam structure by coprecipitation. The nickel particles have a narrow size distribution in several nanometers, and have a strong interaction with other components such as Al2O3. This catalyst is highly sensitive to further modification by doping and to reaction condition. On a modified catalyst, benzene hydrogenation to cyclohexane proceeds to complete at 373 K. While on another catalyst, different structured nanocarbons are obtained at moderate temperatures. It is found that the thioresistance of the nickel catalyst in hydrogenation can be improved by doping.展开更多
Anatase TiO_(2)nanospindles containing 89%exposed{101}facets(TIO_(2)-101)and nanosheets with 77%exposed{001}facets(TiO_(2)-001)were hydrothermally synthesized and used as supports for Pd catalysts.The effects of the T...Anatase TiO_(2)nanospindles containing 89%exposed{101}facets(TIO_(2)-101)and nanosheets with 77%exposed{001}facets(TiO_(2)-001)were hydrothermally synthesized and used as supports for Pd catalysts.The effects of the TiO_(2)materials on the catalytic performance of Pd/TiO_(2)-101 and Pd/TiO_(2)-001 catalysts were investigated in the selective hydrogenation of acetylene to polymer-grade ethylene.The PdfTiO_(2)-101 catalyst exhibited enhanced performance in terms of acetylene conversion and ethylene yield.To understand these effects,the catalysts were characterized by H_(2)temperature-programmed desorption(H_(2)-TPD),H_(2)temperature-programmed reduction(H=-TPR),transmission electron microscopy(TEM),pulse CO chemisorption,X-ray photoelectron spectroscopy(XPS),and thermogravimetric analysis(TGA).The TEM and CO chemisorption results confirmed that Pd nanoparticles(NPs)on the TiO_(2)-101 support had a smaller average particle size(1.53 nm)and a higher dispersion(15.95%)than those on the TiO_(2)-001 support(average particle size of 4.36 nm and dispersion of 9.06%).The smaller particle size and higher dispersion of Pd on the Pd/TiO_(2)-101 catalyst provided more reaction active sites,which contributed to the improved catalytic activity of this supported catalyst.展开更多
Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its ...Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its active sites after adsorbing water, but the remaining was not affected. The reductions of aldehydes and ketones, when promoted by Rb_3PO_4, were allowed at room temperature. The activities of substrates at room temperature followed a descending order of 2,6-dichlorobenzaldehyde> 4-bromobenzaldehyde>benzaldehyde>acetophenone>anisaldehyde>butanone. A new catalytic cycle postulating a six-membered cyclic transition state for the reductions of aldehydes and ketones was proposed. These results exploited the catalytic usage of Rb_3PO_4 and worth in industrial application.展开更多
The hydrogenation reaction characteristics and the properties of its hydrides for the magnetic regenerative material HoCu_2(CeCu_2-type) of a cryocooler were investigated. The XRD testing reveals that the hydrides of ...The hydrogenation reaction characteristics and the properties of its hydrides for the magnetic regenerative material HoCu_2(CeCu_2-type) of a cryocooler were investigated. The XRD testing reveals that the hydrides of HoCu_2 were a mixture of Cu, unknown hydride Ⅰ, and unknown hydride Ⅱ. Based on the PCT(pressure-concentration-temperature) curves under different reaction temperatures, the relationships among reaction temperature, equilibrium pressure, and maximum hydrogen absorption capacity were analyzed and discussed. The enthalpy change ΔH and entropy change ΔS as a result of the whole hydrogenation process were also calculated from the PCT curves. The magnetization and volumetric specific heat capacity of the hydride were also measured by SQUID magnetometer and PPMS, respectively.展开更多
Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural developm...Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural development of the catalyst were observed during CO2 hydrogenation.A mechanism for the deactivation of the catalyst was discussed.The key factors that affect the deactivation of the catalyst were found.Cu nanowire sample was characterized by SEM,EDS,XRD,and BET.The results show that Cu nanowires have very high sintering resistance and catalytic stability.This helps to develop high performance catalysts.The changes in the grain size,SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur.Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels.The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst.However,the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.展开更多
Y zeolite supporting noble metal catalysts, as the important industrial catalysts for aromatics hydrogenation, have received increasing attention in recent years. Pd M/Y bimetallic catalysts, where M is non noble meta...Y zeolite supporting noble metal catalysts, as the important industrial catalysts for aromatics hydrogenation, have received increasing attention in recent years. Pd M/Y bimetallic catalysts, where M is non noble metal element, were prepared to investigate the effects of the addition of a second metal. Pd M/Y catalysts were evaluated under the following conditions: H 2 pressure 4.2 MPa, MHSV 4.0 h -1 , sulfur content in feed 3000 μg/g. The microreactor results indicated that the second metal remarkably affects the hydrogenation activity of Pd/Y catalysts. Among them, Cr and W improve the sulfur resistance of Pd/Y, but La, Mn, Mo and Ag make the sulfur resistance worse and the second metals have no evident influence on product selectivity and acidic properties of the catalysts.展开更多
The Co@NC catalysts with different morphologies were prepared by two step process,solvent control growth and pyrolysis method.The polyhedral Co@NC-67P-450 catalyst has a relatively high CoNx content and exhibits excel...The Co@NC catalysts with different morphologies were prepared by two step process,solvent control growth and pyrolysis method.The polyhedral Co@NC-67P-450 catalyst has a relatively high CoNx content and exhibits excellent phenol hydrogenation activity(conversion 96.9%)at 160℃,3 MPa,which is higher than that of leaf shaped Co@NC-67L-450 catalyst(conversion 75.4%).We demonstrated Co_(3)O_(4)was reduced to the Co^(0)during the reaction.Moreover,CoNx species contribute to the superior hydrogenation activity of phenol.The Co-based catalysts can be easily recovered through the magnetic separation and performed the high stability.展开更多
Recent research progress on the use of Ni-based catalysts supported by various carbon materials,such as carbon nanotubes,graphene,and activated carbon,for the hydrogenation of CO_(2)to CH4 is summarized.The influence ...Recent research progress on the use of Ni-based catalysts supported by various carbon materials,such as carbon nanotubes,graphene,and activated carbon,for the hydrogenation of CO_(2)to CH4 is summarized.The influence of additives and surface modification methods on improving their catalytic performance is discussed as is the reaction mechanism,especially the structurefunction relationship produced by the carbon.The review provides a comprehensive directory for the rational design of carbon-supported Ni-based catalysts for the methanation of CO_(2).展开更多
On the surfaces of celestial bodies with no or thin atmospheres,such as the Moon and Mars,the solar wind irradiation process leads to the formation of hydrogen and helium enriched regions in the extraterrestrial soil ...On the surfaces of celestial bodies with no or thin atmospheres,such as the Moon and Mars,the solar wind irradiation process leads to the formation of hydrogen and helium enriched regions in the extraterrestrial soil particles.However,soil particles on the Earth with the similar composition lack such structures and properties.This discrepancy raises a key question whether there is a direct relationship between solar wind irradiation and the alterations in the structure and chemical performance of extraterrestrial materials.To address this question,this work investigates the effects of proton irradiation,simulating solar wind radiation,on the structure and photothermal catalytic properties of the classic catalyst In_(2)O_(3).It reveals that proton irradiation induces structural features in In_(2)O_(3) analogous to those characteristics of solar wind weathering observed in extraterrestrial materials.Furthermore,after proton beam irradiation with an energy of 30 keV and a dose of 3×10^(17) protons·cm^(-2),the methanol production yield of the In_(2)O_(3) catalyst increased to 2.6 times of its preirradiation level,and the methanol selectivity improved to 2.1 times of the original value.This work provides both theoretical and experimental support for the development of high-efficiency,radiation-resistant photothermal catalysts.展开更多
To achieve efficient catalytic hydrogenation of CO_(2)to formate,we employed a transmetallation strategy to develop three novel iridium(Ⅰ)complexes,which feature N‑heterocyclic carbene‑nitrogen‑phosphine ligands(CNP)...To achieve efficient catalytic hydrogenation of CO_(2)to formate,we employed a transmetallation strategy to develop three novel iridium(Ⅰ)complexes,which feature N‑heterocyclic carbene‑nitrogen‑phosphine ligands(CNP)and a 1,5‑cyclooctadiene(cod)molecule:[Ir(cod)(κ^(3)‑CN^(im)P)]Cl(1⁃Cl),[Ir(cod)(κ^(3)‑CN^(im)P)]PF6(1⁃PF_(6)),and[Ir(cod)(κ^(3)‑CNHP)]Cl(2).The^(1)H NMR spectra,^(31)P NMR spectra,and high‑resolution mass spectra verify the successful synthesis of these three Ir(Ⅰ)‑CNP complexes.Furthermore,single‑crystal X‑ray diffraction analysis confirms the coordination geometry of 1⁃PF_(6).The strong Ir—C(NHC)bond suggests that the carbene carbon plays an enhanced anchoring role to iridium due to its strongσ‑donating ability,which helps stabilize the active metal species during CO_(2)hydrogenation.As a result,the Ir(Ⅰ)‑CNP complex exhibits remarkable activity and long catalytic lifetime for the hydrogenation of CO_(2)to formate,reaching a turnover number(TON)of 1.16×10^(6)after 150 h at a high temperature of 170℃,which was a relatively high value among all the Ir complexes.CCDC:2384071,1⁃PF_(6).展开更多
The hydrogenation rate of styrene in benzene using RhCI（PPh<sub>3</sub>）<sub>3</sub> as catalyst increases with the concentration of styrene. But the hydrogenation rate of cyclohexene is rath...The hydrogenation rate of styrene in benzene using RhCI（PPh<sub>3</sub>）<sub>3</sub> as catalyst increases with the concentration of styrene. But the hydrogenation rate of cyclohexene is rather different, It shows a maximum. So we inquire into the reaction mechanism of cyclohexene hydrogenation catalyzed by RhCI（PPh<sub>3</sub>）<sub>3</sub>. The rate of hydrogenation was measured at 25±0.15℃, as a function. of catalyst concentration, olefin concentration, triphenylphosphine concentration and hydrogen pressure. The maximum of the reaction rate is interpreted by the formation of RhClL<sub>2</sub>S<sub>2</sub>. The rate determining step is considered to be the reaction of olefin insertion into one of the Rh-H bonds formed by hydrogenation of RhClL3 to H<sub>2</sub>RhClL<sub>3</sub>. The hydrogenation rate of the substrate can be described by a third order equation in terms of concentration of H<sub>2</sub>RhClL<sub>3</sub>. Average error between the results evaluated by this equation and experimental results is about 4.9％. The quantum chemistry calculation gives support to the present mechanism.展开更多
The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alka...The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water.Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity.Nevertheless,both the structural characteristics and the underlying mechanism are not well understood,especially for doping with two different atoms,thus limiting the use of these catalysts.We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres(HCNs)by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface,followed by doping with phytic acid and carbonization.The unique pore structure and defect-rich framework of the HCNs expose numerous active sites.Crucially,the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer.As a res-ult,the HCN carbonized at 1100°C exhibited superior HER activity and an outstanding stability(70 h at a current density of 10 mA cm^(−2))in alkaline water,because of the large number of graphitic nitrogen and phosphorus-carbon bonds.展开更多
Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen producti...Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts.In this work,it is found that the prepared Raney Ni W-r treated with high concentration of NaOH(6.25 mol/L)at 110℃exhibited excellent catalytic performance for AB hydrolysis at room temperature.The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials,even higher than that of the 20%Pt/C catalyst.Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency(TOF)value is as high as 51.42 min-1.Owing to its high density and magnetic properties,the catalyst is very easy for magnetic separation.Furthermore,possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed.As a well-established industrial catalyst,Raney Ni has been prepared on a large scale at low cost.This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.展开更多
Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The...Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The hydrogen evolution reaction and iron passivation process on these iron electrodes were investigated in alkaline and neutral solutions.The iron electrode Bi_(2)S_(3)-3@Fe-Gr(The additional amount of Bi_(2)S_(3)was 3 mg)revealed the strongest ability to inhibit hydrogen evolution among the iron electrodes of the present investigation,while the Bi_(2)S_(3)-6@Fe-Gr electrode(The additional amount of Bi_(2)S_(3)was 6 mg)delivered significant performance in inhibiting anodic passivation.This is because the high-energy ball milling process leads to the well-dispersion of Bi_(2)S_(3)and the changes in the surface of Fe nanoparticles,thereby slowing down the passivation of the iron electrode surface.展开更多
文摘The selective hydrogenation ofα,β-unsaturated aldehydes/ketones enables precise control over product structures and properties by regulating hydrogen transport pathways and bond cleavage sequences to selectively reduce C=C or C=O bonds while preserving other functional groups within the molecule.This approach serves as a critical strategy for the directional synthesis of high-value molecules.However,achieving such selectivity remains challenging due to the thermodynamic equilibrium and kinetic competition between C=O and C=C bonds inα,β-unsaturated systems.Consequently,constructing precisely targeted catalytic systems is essential to overcome these limitations,offering both fundamental scientific significance and industrial application potential.Metal-organic frameworks(MOFs)and their derivatives have emerged as innovative platforms for designing such systems,owing to their programmable topology,tunable pore microenvironments,spatially controllable active sites,and modifiable electronic structures.This review systematically summarizes the research progress of MOF-based catalysts for selec-tive hydrogenation ofα,β-unsaturated aldehydes/ketones in the last decade,with emphasis on the design strategy,conformational relationship,and catalytic mechanism,aiming to provide new ideas for the design of targeted catalyt-ic systems for the selective hydrogenation ofα,β-unsaturated aldehydes/ketones.
文摘The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts contained Pd species in mixed valence states,with high valence Pd at the metal‑support interface and zero valence Pd at the metal surface.While the strong coordination of triphenylphosphine(PPh3)to Pd0 on the Pd surface prevents the adsorption of halogenated nitroaromatics and thus dehalogenation,the coordination of sodium metavanadate(NaVO3)to high‑valence Pd sites at the interface helps to activate H2 in a heterolytic pathway for the selective hydrogenation of nitro‑groups.The excellent catalytic performance of the interfacial active sites enables the selective hydrogenation of a wide range of halogenated nitroaromatics.
基金supported by Research Grant from China Petroleum and Chemical Corp。
文摘Cu/ZnO-based catalysts are widely employed for methanol synthesis via CO_(2) hydrogenation.The preparation procedure is sensitive to the particle size and interfacial structure,which are considered as potential active centers influencing the rate of both methanol and CO formation.The particle size and the interaction between Cu and the support materials are influenced by the coprecipitation conditions,let alone that the mechanistic divergence remains unclear.In this work,a series of Cu/ZnO/ZrO_(2) catalysts were prepared via co-precipitation at different pH value and systematically characterized.The structure has been correlated with kinetic results to establish the structure-performance relationship.Kinetic analysis demonstrates that methanol synthesis follows a single-site Langmuir-Hinshelwood(L-H)mechanism,i.e.,Cu serves as the active site where CO_(2) and H_(2) competitively adsorb and react to form methanol.In contrast,CO formation proceeds via a dual-site L-H mechanism,where CO_(2) adsorbs onto ZnO and H_(2) onto Cu,with the reaction occurring at the Cu/ZnO interface.Therefore,for the direct formation of methanol,solely reducing the particle size of Cu would not be beneficial.
文摘The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.
基金supported by the National Natural Science Foundation of China(22302115,22072079)the Fundamental Research Program of Shanxi Province(202303021221056).
文摘Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts.
文摘Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as the strongly enhanced synergistic interactions between Pt and Co atoms,the obtained Pt-on-Co/C400 catalysts exhib-ited excellent catalytic activity toward the hydrolysis of ammonia borane with an extremely high turnover frequency(TOF)value of 3022 min^(-1)at 303 K.Durability test indicated that the obtained Pt-on-Co/C400 catalysts possessed high catalytic stability,and there were no changes in the catalyst structures and catalytic activities after 10 cycles.
基金Supported by the National Natural Science Foundation of China(No. 29792070-9, 29876032).
文摘Highly active and stable nickel catalyst for dehydrogenation of methane and hydrogenation of benzene is prepared from a precursor with hydrotalcite-like anionic clam structure by coprecipitation. The nickel particles have a narrow size distribution in several nanometers, and have a strong interaction with other components such as Al2O3. This catalyst is highly sensitive to further modification by doping and to reaction condition. On a modified catalyst, benzene hydrogenation to cyclohexane proceeds to complete at 373 K. While on another catalyst, different structured nanocarbons are obtained at moderate temperatures. It is found that the thioresistance of the nickel catalyst in hydrogenation can be improved by doping.
文摘Anatase TiO_(2)nanospindles containing 89%exposed{101}facets(TIO_(2)-101)and nanosheets with 77%exposed{001}facets(TiO_(2)-001)were hydrothermally synthesized and used as supports for Pd catalysts.The effects of the TiO_(2)materials on the catalytic performance of Pd/TiO_(2)-101 and Pd/TiO_(2)-001 catalysts were investigated in the selective hydrogenation of acetylene to polymer-grade ethylene.The PdfTiO_(2)-101 catalyst exhibited enhanced performance in terms of acetylene conversion and ethylene yield.To understand these effects,the catalysts were characterized by H_(2)temperature-programmed desorption(H_(2)-TPD),H_(2)temperature-programmed reduction(H=-TPR),transmission electron microscopy(TEM),pulse CO chemisorption,X-ray photoelectron spectroscopy(XPS),and thermogravimetric analysis(TGA).The TEM and CO chemisorption results confirmed that Pd nanoparticles(NPs)on the TiO_(2)-101 support had a smaller average particle size(1.53 nm)and a higher dispersion(15.95%)than those on the TiO_(2)-001 support(average particle size of 4.36 nm and dispersion of 9.06%).The smaller particle size and higher dispersion of Pd on the Pd/TiO_(2)-101 catalyst provided more reaction active sites,which contributed to the improved catalytic activity of this supported catalyst.
基金Project(21576074)supported by the National Natural Science Foundation of China
文摘Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its active sites after adsorbing water, but the remaining was not affected. The reductions of aldehydes and ketones, when promoted by Rb_3PO_4, were allowed at room temperature. The activities of substrates at room temperature followed a descending order of 2,6-dichlorobenzaldehyde> 4-bromobenzaldehyde>benzaldehyde>acetophenone>anisaldehyde>butanone. A new catalytic cycle postulating a six-membered cyclic transition state for the reductions of aldehydes and ketones was proposed. These results exploited the catalytic usage of Rb_3PO_4 and worth in industrial application.
基金Project(51276154)supported by the National Natural Science Foundation of ChinaProject(2012010111014)supported by the University Doctoral Subject Special Foundation of China
文摘The hydrogenation reaction characteristics and the properties of its hydrides for the magnetic regenerative material HoCu_2(CeCu_2-type) of a cryocooler were investigated. The XRD testing reveals that the hydrides of HoCu_2 were a mixture of Cu, unknown hydride Ⅰ, and unknown hydride Ⅱ. Based on the PCT(pressure-concentration-temperature) curves under different reaction temperatures, the relationships among reaction temperature, equilibrium pressure, and maximum hydrogen absorption capacity were analyzed and discussed. The enthalpy change ΔH and entropy change ΔS as a result of the whole hydrogenation process were also calculated from the PCT curves. The magnetization and volumetric specific heat capacity of the hydride were also measured by SQUID magnetometer and PPMS, respectively.
基金Project(51074205)supported by the National Natural Science Foundation of China
文摘Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural development of the catalyst were observed during CO2 hydrogenation.A mechanism for the deactivation of the catalyst was discussed.The key factors that affect the deactivation of the catalyst were found.Cu nanowire sample was characterized by SEM,EDS,XRD,and BET.The results show that Cu nanowires have very high sintering resistance and catalytic stability.This helps to develop high performance catalysts.The changes in the grain size,SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur.Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels.The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst.However,the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.
文摘Y zeolite supporting noble metal catalysts, as the important industrial catalysts for aromatics hydrogenation, have received increasing attention in recent years. Pd M/Y bimetallic catalysts, where M is non noble metal element, were prepared to investigate the effects of the addition of a second metal. Pd M/Y catalysts were evaluated under the following conditions: H 2 pressure 4.2 MPa, MHSV 4.0 h -1 , sulfur content in feed 3000 μg/g. The microreactor results indicated that the second metal remarkably affects the hydrogenation activity of Pd/Y catalysts. Among them, Cr and W improve the sulfur resistance of Pd/Y, but La, Mn, Mo and Ag make the sulfur resistance worse and the second metals have no evident influence on product selectivity and acidic properties of the catalysts.
基金The National Natural Science Foundation of China(22102194)The Science and Technology Plan of Gansu Province(20JR10RA044)The Youth Innovation Promotion Association of CAS(2022427).
文摘The Co@NC catalysts with different morphologies were prepared by two step process,solvent control growth and pyrolysis method.The polyhedral Co@NC-67P-450 catalyst has a relatively high CoNx content and exhibits excellent phenol hydrogenation activity(conversion 96.9%)at 160℃,3 MPa,which is higher than that of leaf shaped Co@NC-67L-450 catalyst(conversion 75.4%).We demonstrated Co_(3)O_(4)was reduced to the Co^(0)during the reaction.Moreover,CoNx species contribute to the superior hydrogenation activity of phenol.The Co-based catalysts can be easily recovered through the magnetic separation and performed the high stability.
文摘Recent research progress on the use of Ni-based catalysts supported by various carbon materials,such as carbon nanotubes,graphene,and activated carbon,for the hydrogenation of CO_(2)to CH4 is summarized.The influence of additives and surface modification methods on improving their catalytic performance is discussed as is the reaction mechanism,especially the structurefunction relationship produced by the carbon.The review provides a comprehensive directory for the rational design of carbon-supported Ni-based catalysts for the methanation of CO_(2).
基金National Key Research and Development Program of China(2020YFA0710302)The Major Research Plan of the National Natural Science Foundation of China(91963206)+2 种基金The National Natural Science Foundation of China(52072169,51972164,51972167,22279053)The Fundamental Research Funds for the Central Universities(14380193)The Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2019ZT08L101).
文摘On the surfaces of celestial bodies with no or thin atmospheres,such as the Moon and Mars,the solar wind irradiation process leads to the formation of hydrogen and helium enriched regions in the extraterrestrial soil particles.However,soil particles on the Earth with the similar composition lack such structures and properties.This discrepancy raises a key question whether there is a direct relationship between solar wind irradiation and the alterations in the structure and chemical performance of extraterrestrial materials.To address this question,this work investigates the effects of proton irradiation,simulating solar wind radiation,on the structure and photothermal catalytic properties of the classic catalyst In_(2)O_(3).It reveals that proton irradiation induces structural features in In_(2)O_(3) analogous to those characteristics of solar wind weathering observed in extraterrestrial materials.Furthermore,after proton beam irradiation with an energy of 30 keV and a dose of 3×10^(17) protons·cm^(-2),the methanol production yield of the In_(2)O_(3) catalyst increased to 2.6 times of its preirradiation level,and the methanol selectivity improved to 2.1 times of the original value.This work provides both theoretical and experimental support for the development of high-efficiency,radiation-resistant photothermal catalysts.
文摘To achieve efficient catalytic hydrogenation of CO_(2)to formate,we employed a transmetallation strategy to develop three novel iridium(Ⅰ)complexes,which feature N‑heterocyclic carbene‑nitrogen‑phosphine ligands(CNP)and a 1,5‑cyclooctadiene(cod)molecule:[Ir(cod)(κ^(3)‑CN^(im)P)]Cl(1⁃Cl),[Ir(cod)(κ^(3)‑CN^(im)P)]PF6(1⁃PF_(6)),and[Ir(cod)(κ^(3)‑CNHP)]Cl(2).The^(1)H NMR spectra,^(31)P NMR spectra,and high‑resolution mass spectra verify the successful synthesis of these three Ir(Ⅰ)‑CNP complexes.Furthermore,single‑crystal X‑ray diffraction analysis confirms the coordination geometry of 1⁃PF_(6).The strong Ir—C(NHC)bond suggests that the carbene carbon plays an enhanced anchoring role to iridium due to its strongσ‑donating ability,which helps stabilize the active metal species during CO_(2)hydrogenation.As a result,the Ir(Ⅰ)‑CNP complex exhibits remarkable activity and long catalytic lifetime for the hydrogenation of CO_(2)to formate,reaching a turnover number(TON)of 1.16×10^(6)after 150 h at a high temperature of 170℃,which was a relatively high value among all the Ir complexes.CCDC:2384071,1⁃PF_(6).
文摘The hydrogenation rate of styrene in benzene using RhCI（PPh<sub>3</sub>）<sub>3</sub> as catalyst increases with the concentration of styrene. But the hydrogenation rate of cyclohexene is rather different, It shows a maximum. So we inquire into the reaction mechanism of cyclohexene hydrogenation catalyzed by RhCI（PPh<sub>3</sub>）<sub>3</sub>. The rate of hydrogenation was measured at 25±0.15℃, as a function. of catalyst concentration, olefin concentration, triphenylphosphine concentration and hydrogen pressure. The maximum of the reaction rate is interpreted by the formation of RhClL<sub>2</sub>S<sub>2</sub>. The rate determining step is considered to be the reaction of olefin insertion into one of the Rh-H bonds formed by hydrogenation of RhClL3 to H<sub>2</sub>RhClL<sub>3</sub>. The hydrogenation rate of the substrate can be described by a third order equation in terms of concentration of H<sub>2</sub>RhClL<sub>3</sub>. Average error between the results evaluated by this equation and experimental results is about 4.9％. The quantum chemistry calculation gives support to the present mechanism.
基金financially supported by the project of the National Natural Science Foundation of China(52322203)the Key Research and Development Program of Shaanxi Province(2024GHZDXM-21)。
文摘The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water.Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity.Nevertheless,both the structural characteristics and the underlying mechanism are not well understood,especially for doping with two different atoms,thus limiting the use of these catalysts.We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres(HCNs)by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface,followed by doping with phytic acid and carbonization.The unique pore structure and defect-rich framework of the HCNs expose numerous active sites.Crucially,the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer.As a res-ult,the HCN carbonized at 1100°C exhibited superior HER activity and an outstanding stability(70 h at a current density of 10 mA cm^(−2))in alkaline water,because of the large number of graphitic nitrogen and phosphorus-carbon bonds.
基金supported by the National Natural Science Foundation of China(21908135)Natural Science Foundation of Shanxi Datong University(2022K23)+1 种基金Graduate Research Innovation and Practice Innovation Projects of Shanxi Datong University(23CX31)Postgraduate Educational Reform and Research Program of Shanxi Datong University(23JG07)。
文摘Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts.In this work,it is found that the prepared Raney Ni W-r treated with high concentration of NaOH(6.25 mol/L)at 110℃exhibited excellent catalytic performance for AB hydrolysis at room temperature.The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials,even higher than that of the 20%Pt/C catalyst.Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency(TOF)value is as high as 51.42 min-1.Owing to its high density and magnetic properties,the catalyst is very easy for magnetic separation.Furthermore,possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed.As a well-established industrial catalyst,Raney Ni has been prepared on a large scale at low cost.This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.
文摘Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The hydrogen evolution reaction and iron passivation process on these iron electrodes were investigated in alkaline and neutral solutions.The iron electrode Bi_(2)S_(3)-3@Fe-Gr(The additional amount of Bi_(2)S_(3)was 3 mg)revealed the strongest ability to inhibit hydrogen evolution among the iron electrodes of the present investigation,while the Bi_(2)S_(3)-6@Fe-Gr electrode(The additional amount of Bi_(2)S_(3)was 6 mg)delivered significant performance in inhibiting anodic passivation.This is because the high-energy ball milling process leads to the well-dispersion of Bi_(2)S_(3)and the changes in the surface of Fe nanoparticles,thereby slowing down the passivation of the iron electrode surface.
