Researchers have been attempting to characterize heterogeneous catalysts in situ in addition to correlating their structures with their activity and selectivity in spite of many challenges.Here,we review recent experi...Researchers have been attempting to characterize heterogeneous catalysts in situ in addition to correlating their structures with their activity and selectivity in spite of many challenges.Here,we review recent experimental and theoretical advances regarding alkyne selective hydrogenation by Pd‐based catalysts,which are an important petrochemical reaction.The catalytic selectivity for the reaction of alkynes to alkenes is influenced by the composition and structure of the catalysts.Recent progress achieved through experimental studies and atomic simulations has provided useful insights into the origins of the selectivity.The important role of the subsurface species(H and C)was revealed by monitoring the catalyst surface and the related catalytic performance.The atomic structures of the Pd catalytic centers and their relationship with selectivity were established through atomic simulations.The combined knowledge gained from experimental and theoretical studies provides a fundamental understanding of catalytic mechanisms and reveals a path toward improved catalyst design.展开更多
Highly selective electrocatalytic semihydrogenation of alkynes to alkenes with water as the hydrogen source over palladium-based electrocatalysts is significant but remains a great challenge because of the excessive h...Highly selective electrocatalytic semihydrogenation of alkynes to alkenes with water as the hydrogen source over palladium-based electrocatalysts is significant but remains a great challenge because of the excessive hydrogenation capacity of palladium.Here,we propose that an ideal palladium catalyst should possess weak alkene adsorption and inhibit subsurface hydrogen formation to stimulate the high selectivity of alkyne semihydrogenation.Therefore,sulfur-modified Pd nanowires(Pd-S NWs)are designedly prepared by a solid-solution interface sulfuration method with KSCN as the sulfur source.The introduction of S weakens the alkene adsorption and prevents the diffusion of active hydrogen(H^(*))into the Pd lattice to form unfavorable subsurface H^(*).As a result,electrocatalytic alkyne semihydrogenation is achieved over a Pd-S NWs cathode with wide substrate scopes,potential-independent up to 99%alkene selectivity,good fragile groups compatibility,and easily synthesized deuterated alkenes.An adsorbed hydrogen addition mechanism of this semihydrogenation reaction is proposed.Importantly,an easy modification of commercial Pd/C by in situ addition of SCN–enabling the gram-scale synthesis of an alkene with 99%selectivity and 95%conversion highlights the promising potential of our method.展开更多
The modulating effects of Cu modification and oxalate or borohydride ligands functionalization on the structure,catalyst d-band center(εd),upper d-band edge(εu),and acetylene partial hydrogenation of expediently syn...The modulating effects of Cu modification and oxalate or borohydride ligands functionalization on the structure,catalyst d-band center(εd),upper d-band edge(εu),and acetylene partial hydrogenation of expediently synthesized Ce alloyed Pt supported catalysts were investigated.Firstly,a 5 wt%Pt alloyed Ce was synthesized via flame spray pyrolysis.The PtCe sample was further supported on zeolite Y,ZY,(PtCe/ZY)and copper modified ZY(PtCe/Cu-ZY).Furthermore,the PtCe was supported on two other oxalate and borohydride ligands functionalized copper modified ZY(PtCe/CuX-ZY and PtCe/CuB-ZY,respectively).The high-angle annular darkfield scanning transmission electron microscopy(HAADF/STEM)data showed a reduction in the PtO average particle size from 2.65 nm in PtCeO_(2) to average 1.73,0.64,and 0.30 nm in PtCe/Cu-ZY,PtCe/CuX-ZY,and PtCe/CuB-ZY,which was corroborated by the electron energy-loss spectroscopy(EELS)results wherein nonhomogeneous mixing of elements was seen with segregated Pt clusters in the non-functionalized samples.Conversely,both PtCe/CuX-ZY and PtCe/CuBZY samples showed near-perfect homogeneity with no distinct Pt signals.The measuredεu values for PtCe,PtCe/Cu-ZY,PtCe/CuX-ZY,and PtCe/CuB-ZY are+1.85,+0.40,-0.15,and-0.19 eV,respectively.The positive values indicated strong metal-adsorbate bonding typical of large Pt sizes while the negative values indicated weak metal-adsorbate bonding due to highly downsized Pt sizes.The ethylene yield(YC2H4)over the PtCe sample showed depletion as the reaction temperature increased,while it reflected maxima at 120℃ with 55.3%YC2H4 over PtCe/ZY.The maxima shifted to 180℃ with enhanced YC2H4 of 71.4%in PtCe/Cu-ZY.On the contrary,both PtCe/CuX-ZY and PtCe/CuB-ZY exhibited a monotonous increase in YC2H4 up to the maximum C_(2)H_(2)conversion with YC2H4 of 81.9%and 92.1%at 180 and 160℃,respectively.These results showed that both the Cu modification and ligands functionalization were highly invaluable to enhance the properties and activities of the semihydrogenation of acetylene(SHA)catalysts.展开更多
Selective semihydrogenation of acetylene to ethylene is an industrially critical purification step[1].In petrochemical plants,trace acetylene(<<1 vol%)must be removed from cracker-derived ethylene to protect dow...Selective semihydrogenation of acetylene to ethylene is an industrially critical purification step[1].In petrochemical plants,trace acetylene(<<1 vol%)must be removed from cracker-derived ethylene to protect downstream ZieglerNatta polymerisation catalysts and ensure product quality.展开更多
Synthesis of valuable(Z)-1;2-dialkyl alkenes via cis-semihydrogenation of alkynes is often plagued by side reactions such as alkene isomerization and over-reduction.Here we report a catalyst-state induced color-change...Synthesis of valuable(Z)-1;2-dialkyl alkenes via cis-semihydrogenation of alkynes is often plagued by side reactions such as alkene isomerization and over-reduction.Here we report a catalyst-state induced color-change(CatSICC)strategy for precise detection of reaction endpoint of transfer hydrogenation(TH);enabling highly efficient and cis-selective semihydrogenation of dialkyl alkynes with EtOH as H-donor.A series of NHC carbene-containing pincer iridium complexes(PCC_(NHC))IrHX(X=Br or I)have been prepared and applied to the TH reaction.Monitoring the TH process reveals a vibrant color-change of the solution from purple to yellow-orange as a result of transition of the catalyst-state from(PCC_(NHC))Ir(alkyne)to(PCC_(NHC))IrHMe(CO);signifying the complete conversion of alkyne substrate.Quenching the reaction timely according to the color-change allows access to(Z)-1;2-dialkyl alkenes with very high efficiency;exquisite precision;and broad functional group tolerance.The reliability and practicability of this protocol is demonstrated by cis-semihydrogenation of complex polyfunctionalized bioactive molecules.Mechanistic studies establish that the propensity of(PCC_(NHC))Ir to undergo facile EtOH decarbonylation to form isomerization-inactive species(PCC_(NHC))IrHMe(CO)only when the semihydrogenation reaction is completed is important to stereo-and chemoselectivity control.展开更多
Semihydrogenation of trace acetylene in an ethylene gas stream is a vital step for the industrial production of polyethylene,in which Pd single-site catalysts(SSCs)have great potential.Herein,two Pd SSCs with differen...Semihydrogenation of trace acetylene in an ethylene gas stream is a vital step for the industrial production of polyethylene,in which Pd single-site catalysts(SSCs)have great potential.Herein,two Pd SSCs with different coordination structures are prepared on hierarchical nitrogen-doped carbon nanocages(hNCNC)by regulating the nitrogen species with or without using dicyandiamide.With using dicyandiamide,the obtained Pd1-Ndicy/hNCNC SSC features the coordinated Pd by two pyridinic N and two pyrrolic N(PdN^(py)_(2)N^(pr)_(2)).Without using dicyandiamide,the obtained Pd1/hNCNC SSC features the coordinated Pd by pyridinic N and C(PdN^(py_(x)C_(4-x)),x=1-4).The former exhibits an 18-fold increase in catalytic activity compared to the latter.Theoretical results reveal the abundant unoccupied orbital states above the Fermi level of moiety,which can facilitate the activation of substrate molecules and dynamics of acetylene hydrogenation as supported by the combined theoretical and experimental results.In addition,PdN^(py)_(2)N^(pr)_(2)the moiety presents a favorable desorption of ethylene.Consequently,the Pd1-Ndicy/hNCNC SSC exhibits high C2H2 conversion(99%)and C2H4 selectivity(87%)at 160℃.This study demonstrates the impact of Pd single-site coordination structure on catalytic performance,which is significant for the rational design of advanced Pd SSCs on carbon-based supports.展开更多
Molecular catalysts can effectively steer the electrocatalytic acetylene semihydrogenation into ethylene,but realizing high Faradaic efficiency(FE)at industrial current densities remains a challenge.Herein,we report a...Molecular catalysts can effectively steer the electrocatalytic acetylene semihydrogenation into ethylene,but realizing high Faradaic efficiency(FE)at industrial current densities remains a challenge.Herein,we report a ligand engineering strategy that utilizes polymeric N–heterocyclic carbene(NHC)as a hydrophobic ligand to modulate the microenvironment of Cu sites.This polymeric NHC imparts appropriate hydrophobic properties for the chelated Cu sites,thereby moderating the H_(2)O transport and enabling easy access of acetylene.Consequently,the polymeric NHC chelated Cu exhibits an FE_(ethylene)of~97%at a current density of 500 m A/cm^(2)in a flow cell.Particularly in a zero-gap reactor,the FE_(ethylene)consistently exceeds 86%across current densities from 100 m A/cm^(2)to 400 m A/cm^(2),reaching an optimal FEethyleneof 98%at 200 m A/cm^(2)and achieving durable operation for 155 h at 100 m A/cm^(2).This work provides a promising paradigm to regulate the microenvironment of molecular catalysts for improving electrocatalytic performances under industrial current densities.展开更多
Selective semihydrogenation of acetylene in raw olefin streams to ethylene is a key industrial reaction to produce polymer-grade feeds for the manufacture of corresponding polymers.The currently used process in indust...Selective semihydrogenation of acetylene in raw olefin streams to ethylene is a key industrial reaction to produce polymer-grade feeds for the manufacture of corresponding polymers.The currently used process in industry is the thermocatalytic acetylene semihydrogenation with pressurized hydrogen and Pd-based catalysts at relatively high temperatures.The high cost of Pd urgently desires the design of non-noble metal-based catalysts.However,non-noble metal-based catalysts commonly require much higher reaction temperatures than Pd-based catalysts because of their poor intrinsic activity.Therefore,aiming at increasing economic efficiency and sustainability,various strategies are explored for developing non-noble metal-based catalysts for thermocatalytic and green acetylene semihydrogenation processes.In this review,we systematically summarize the recent advances in catalytic technology from thermocatalysis to sustainable alternatives,as well as corresponding regulation strategies for designing high-performance non-noble metal-based catalysts.The crucial factors affecting catalytic performance are discussed,and the fundamental structure-performance correlation of catalysts is outlined.Meanwhile,we emphasize current challenging issues and future perspectives for acetylene semihydrogenation.This review will not only promote the rapid exploration of non-noble metal-based catalysts for acetylene semihydrogenation,but also advance the development of sustainable processes like electrocatalysis and photocatalysis.展开更多
The promoting effect of sulfur sources is an intriguing but poorly understood phenomenon. Herein, we studied the treatment of PdCu bimetallic nanoparticles （NPs） with different amounts of sulfur powder. Low-level su...The promoting effect of sulfur sources is an intriguing but poorly understood phenomenon. Herein, we studied the treatment of PdCu bimetallic nanoparticles （NPs） with different amounts of sulfur powder. Low-level sulfidation led to the generation of a Pd30CuloS9 NP catalyst consisting of surface enriched Pd NPs, electron deficient Pd and Cu, as well as zero valence sulfur. The Pd30CuloS9 NP catalyst showed pronouncedly enhanced activity and selectivity in the semihydrogenation of alkynes. Our study revealed for the first time a possible cause for the promoting effect of sulfur at the atomic level, suggesting a new strategy in catalyst design.展开更多
Atomically dispersed catalysts have demonstrated superior catalytic performance in many chemical transformations.However,limited success has been achieved in applying oxide-supported atomically dis-persed catalysts to...Atomically dispersed catalysts have demonstrated superior catalytic performance in many chemical transformations.However,limited success has been achieved in applying oxide-supported atomically dis-persed catalysts to semihydrogenation of alkynes under mild conditions.展开更多
Enhancing the selectivity of noble metal catalysts through electronic modulation is important for academic research and chemical industrial processes.Herein,we report a facile sacrificial template strategy for the syn...Enhancing the selectivity of noble metal catalysts through electronic modulation is important for academic research and chemical industrial processes.Herein,we report a facile sacrificial template strategy for the synthesis of PdZn intermetallic compound(3-4 nm)highly distributed in ZnO/nitrogen-decorated carbon hollow spheres(PdZn-ZnO/NCHS)to optimize the selectivity of Pd catalysts,which involves carbonization of a core-shell structured polystyrene(PS)@ZIF-8 precursor in an inert atmosphere,impregnation Pd precursor,and subsequent H2 reduction treatment.Due to the unique structural and compositional features,the developed PdZn-ZnO/NCHS delivers an excellent catalytic performance for the semihydrogenation of 2-methyl-3-butyn-2-ol(MBY)to 2-methyl-3-buten-2-ol(MBE)with high activity(>99%),high selectivity(96%),and good recyclability,outperforming the analog Pd on ZnO(Pd/ZnO)as well as the supported Pd nanoparticles(Pd/C and Pd/NC).Density functional theory(DFT)calculations reveal that the presence of Znδ+species in PdZn-ZnO/NCHS alters the adsorption modes of reactant and product,leading to a decrease of the adsorption strength and an enhancement of the energy barrier for overhydrogenation,which results in a kinetic favor for the selective transformation of MBY to MBE.In addition,PdZn-ZnO/NCHS was also very effective for the partial hydrogenation of dehydrolinalool to hydrolinalool.展开更多
Alkenols are important intermediates for the industrial manufacture of various commodities and fine chemicals.At present,alkenols are produced via thermocatalytic semihydrogenation of corresponding alkynols using prec...Alkenols are important intermediates for the industrial manufacture of various commodities and fine chemicals.At present,alkenols are produced via thermocatalytic semihydrogenation of corresponding alkynols using precious metal Pd-based catalysts in pressurized hydrogen atmosphere.In this work,we highlight an efficient electrocatalytic strategy for selectively reducing alkynols to alkenols under ambient conditions.Using 2-methyl-3-butyn-2-ol as a model alkynol,Cu3P nanoarrays anchored on Cu foam remarkably deliver an industrial-level partial current density of 0.79 A·cm^(-2) and a specific selectivity of 98%for 2-methyl-3-buten-2-ol in acidic solution.Over a 40-runs stability test,Cu3P nanoarrays maintain 90%alkynol conversion and 90%alkenol selectivity.Even in a large two-electrode flow electrolyser,the single-pass alkynol conversion and alkenol selectivity of Cu3P nanoarrays exceed 90%.Moreover,this selective electrocatalytic hydrogenation approach is broadly feasible for the production of various water-soluble alkenols.Electrochemical analyses,theoretical simulation and electrochemical in-situ infrared investigations together reveal that exothermic alkynol hydrogenation,facile alkenol desorption and formation of active H on Cu3P surfaces account for the excellent electrocatalytic performance.展开更多
Combining the advantages of both heterogeneous and homogeneous catalysts,single-atom catalysts(SACs)with unique electronic properties have shown excellent catalytic properties.Herein,we report single-atom Pd dispersed...Combining the advantages of both heterogeneous and homogeneous catalysts,single-atom catalysts(SACs)with unique electronic properties have shown excellent catalytic properties.Herein,we report single-atom Pd dispersed on nanoscale TiO2 prepared by self-assembly method as efficient and selective catalysts for the hydrogenation of phenylacetylene to styrene.The catalysts were characterized by N2 adsorption/desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and X-ray absorption spectroscopy(XAS).0.2 Pd-TiO2(150℃)possessing dominant single-atom Pd species,exhibited a turnover frequency(TOF)of over 8000 h^-1 with 91%selectivity towards styrene at room temperature.Further increasing Pd loading from 0.2%to 0.5%and 1.5%resulted in the decrease of activity probably due to the formation of Pd nanoparticles.Besides,the 0.2 Pd-TiO2 prepared by self-assembly strategy showed better catalytic performance than commercial 10%Pd/C and0.2 Pd-TiO2 synthesized by using impregnation method.展开更多
Modulation of geometric and electronic structures of supported Pd-based catalysts by forming atomically ordered intermetallic phases enables an effective way to optimize catalytic performance.However,the synthesis of ...Modulation of geometric and electronic structures of supported Pd-based catalysts by forming atomically ordered intermetallic phases enables an effective way to optimize catalytic performance.However,the synthesis of small-sized Pd-based intermetallic nanoparticle catalysts with improved mass-based activity remains formidable challenges,since high-temperature annealing generally required for atom ordering inevitably leads to severe metal sintering and thus large crystallites.Here,we present a bulky nanodiamond-confined method to prepare sub-5 nm Pd_(3)Pb intermetallic nanocatalysts by mitigating metal sintering at high temperatures,which is induced by the electronic interactions between metal and defect-rich graphene shells reinforced by diamond cores in the bulky nanodiamond support.The prepared small-sized Pd_(3)Pb intermetallic catalyst displays a high activity with a turnover frequency of 932 h−1 for the semihydrogenation of phenylacetylene under mild conditions(room temperature,3 bar H_(2)),along with a high selectivity of>96%to styrene near the complete conversion of phenylacetylene.展开更多
Owing to serious poison of downstream olefin polymerization catalysts from acetylene impurities,selective reduction of acetylene to ethylene is a pivotal process in petrochemical industry.However,during thermocatalyti...Owing to serious poison of downstream olefin polymerization catalysts from acetylene impurities,selective reduction of acetylene to ethylene is a pivotal process in petrochemical industry.However,during thermocatalytic and electrocatalytic acetylene semihydrogenation,acetylene C-C coupling inevitably occurs on current catalysts.The resultant oligomeric species(particularly long-chain hydrocarbons)block active sites and mass transportation,and eventually decrease catalytic activity and stability.In this work,we report Ag nanowires(NWs)as high-performance electrocatalysts for acetylene semihydrogenation,where the C-C coupling is unprecedentedly suppressed by weakening acetylene adsorption.In pure acetylene,1,3-butadiene Faradaic efficiency(FE)of Ag NWs is only 2.1%,which is far lower than 41.2%for Cu nanoparticles at−0.2 V versus reversible hydrsogen electrode.Ethylene partial current density of Ag NWs reaches 217 mA/cm^(2)at 0.85 V,which is considerably higher than those for state-of-the-art Cu-based electrocatalysts.Markedly,no 1,3-butadiene is produced on Ag NWs in a large two-electrode flow cell fed with crude ethylene containing 1 vol%acetylene,presenting thorough termination of acetylene C-C coupling.In situ electrochemical Raman spectroscopy and theoretical investigations reveal that weak acetylene adsorption on Ag surfaces is intrinsically responsible for prohibiting their oligomerization.This work will spark the rapid development of high-performance and stable electrocatalysts for reducing alkynes to olefins.展开更多
Catalytic hydrogenation is a foundational pillar of the chemical industry.Especially,semi-hydrogenation of acetylene(C_(2)H_(2))to ethylene(C_(2)H_(4))is an important industrial reaction to generate polymer-grade C_(2...Catalytic hydrogenation is a foundational pillar of the chemical industry.Especially,semi-hydrogenation of acetylene(C_(2)H_(2))to ethylene(C_(2)H_(4))is an important industrial reaction to generate polymer-grade C_(2)H_(4) from crude streams for polyethylene production.The industrial C_(2)H_(2) semi-hydrogenation process is currently dominated by the thermocatalytic route that involves cost-prohibitive Pdbased catalysts,high operation temperature,and excess hydrogen feed.Thermocatalytic semi-hydrogenation of C_(2)H_(2) is also hindered by limited C_(2)H_(4) selectivity due to unwanted over-hydrogenation.Therefore,seeking strategies to improve the catalyst performance while reducing energy consumption and capital expenditure of the current hydrogenation schemes is essential to the petrochemical industry.Fortunately,recent advances in electrocatalytic C_(2)H_(2) semi-hydrogenation systems lead to a sustainable alternative to traditional thermocatalytic systems.Using renewable electricity as an energy source and water as a hydrogen source,electrocatalytic systems can operate under ambient conditions with tunable selectivity toward C_(2)H_(4).In this review,we first discuss the reactor design for electrocatalytic C_(2)H_(2) semi-hydrogenation.We then review the computational studies for understanding and predicting the catalytic behavior ofmetal catalysts.We also summarize advanced electrocatalysts categorized into Cu-based and non-Cu-based materials.Finally,we provide perspectives on the opportunities to overcome existing challenges for future practical application of electrocatalytic C_(2)H_(2) semihydrogenation.展开更多
文摘Researchers have been attempting to characterize heterogeneous catalysts in situ in addition to correlating their structures with their activity and selectivity in spite of many challenges.Here,we review recent experimental and theoretical advances regarding alkyne selective hydrogenation by Pd‐based catalysts,which are an important petrochemical reaction.The catalytic selectivity for the reaction of alkynes to alkenes is influenced by the composition and structure of the catalysts.Recent progress achieved through experimental studies and atomic simulations has provided useful insights into the origins of the selectivity.The important role of the subsurface species(H and C)was revealed by monitoring the catalyst surface and the related catalytic performance.The atomic structures of the Pd catalytic centers and their relationship with selectivity were established through atomic simulations.The combined knowledge gained from experimental and theoretical studies provides a fundamental understanding of catalytic mechanisms and reveals a path toward improved catalyst design.
文摘Highly selective electrocatalytic semihydrogenation of alkynes to alkenes with water as the hydrogen source over palladium-based electrocatalysts is significant but remains a great challenge because of the excessive hydrogenation capacity of palladium.Here,we propose that an ideal palladium catalyst should possess weak alkene adsorption and inhibit subsurface hydrogen formation to stimulate the high selectivity of alkyne semihydrogenation.Therefore,sulfur-modified Pd nanowires(Pd-S NWs)are designedly prepared by a solid-solution interface sulfuration method with KSCN as the sulfur source.The introduction of S weakens the alkene adsorption and prevents the diffusion of active hydrogen(H^(*))into the Pd lattice to form unfavorable subsurface H^(*).As a result,electrocatalytic alkyne semihydrogenation is achieved over a Pd-S NWs cathode with wide substrate scopes,potential-independent up to 99%alkene selectivity,good fragile groups compatibility,and easily synthesized deuterated alkenes.An adsorbed hydrogen addition mechanism of this semihydrogenation reaction is proposed.Importantly,an easy modification of commercial Pd/C by in situ addition of SCN–enabling the gram-scale synthesis of an alkene with 99%selectivity and 95%conversion highlights the promising potential of our method.
文摘The modulating effects of Cu modification and oxalate or borohydride ligands functionalization on the structure,catalyst d-band center(εd),upper d-band edge(εu),and acetylene partial hydrogenation of expediently synthesized Ce alloyed Pt supported catalysts were investigated.Firstly,a 5 wt%Pt alloyed Ce was synthesized via flame spray pyrolysis.The PtCe sample was further supported on zeolite Y,ZY,(PtCe/ZY)and copper modified ZY(PtCe/Cu-ZY).Furthermore,the PtCe was supported on two other oxalate and borohydride ligands functionalized copper modified ZY(PtCe/CuX-ZY and PtCe/CuB-ZY,respectively).The high-angle annular darkfield scanning transmission electron microscopy(HAADF/STEM)data showed a reduction in the PtO average particle size from 2.65 nm in PtCeO_(2) to average 1.73,0.64,and 0.30 nm in PtCe/Cu-ZY,PtCe/CuX-ZY,and PtCe/CuB-ZY,which was corroborated by the electron energy-loss spectroscopy(EELS)results wherein nonhomogeneous mixing of elements was seen with segregated Pt clusters in the non-functionalized samples.Conversely,both PtCe/CuX-ZY and PtCe/CuBZY samples showed near-perfect homogeneity with no distinct Pt signals.The measuredεu values for PtCe,PtCe/Cu-ZY,PtCe/CuX-ZY,and PtCe/CuB-ZY are+1.85,+0.40,-0.15,and-0.19 eV,respectively.The positive values indicated strong metal-adsorbate bonding typical of large Pt sizes while the negative values indicated weak metal-adsorbate bonding due to highly downsized Pt sizes.The ethylene yield(YC2H4)over the PtCe sample showed depletion as the reaction temperature increased,while it reflected maxima at 120℃ with 55.3%YC2H4 over PtCe/ZY.The maxima shifted to 180℃ with enhanced YC2H4 of 71.4%in PtCe/Cu-ZY.On the contrary,both PtCe/CuX-ZY and PtCe/CuB-ZY exhibited a monotonous increase in YC2H4 up to the maximum C_(2)H_(2)conversion with YC2H4 of 81.9%and 92.1%at 180 and 160℃,respectively.These results showed that both the Cu modification and ligands functionalization were highly invaluable to enhance the properties and activities of the semihydrogenation of acetylene(SHA)catalysts.
文摘Selective semihydrogenation of acetylene to ethylene is an industrially critical purification step[1].In petrochemical plants,trace acetylene(<<1 vol%)must be removed from cracker-derived ethylene to protect downstream ZieglerNatta polymerisation catalysts and ensure product quality.
基金supported by the National Key R&D Program of China(2021YFA1501700)the National Natural Science Foundation of China(22425012,22072178,22293013,21821002)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0610000)the CAS Project for Young Scientists in Basic Research(YSBR-094)the CAS Youth Interdisciplinary Team(JCTD-2021-11)Science and Technology Commission of Shanghai Municipality(23JC1404400).
文摘Synthesis of valuable(Z)-1;2-dialkyl alkenes via cis-semihydrogenation of alkynes is often plagued by side reactions such as alkene isomerization and over-reduction.Here we report a catalyst-state induced color-change(CatSICC)strategy for precise detection of reaction endpoint of transfer hydrogenation(TH);enabling highly efficient and cis-selective semihydrogenation of dialkyl alkynes with EtOH as H-donor.A series of NHC carbene-containing pincer iridium complexes(PCC_(NHC))IrHX(X=Br or I)have been prepared and applied to the TH reaction.Monitoring the TH process reveals a vibrant color-change of the solution from purple to yellow-orange as a result of transition of the catalyst-state from(PCC_(NHC))Ir(alkyne)to(PCC_(NHC))IrHMe(CO);signifying the complete conversion of alkyne substrate.Quenching the reaction timely according to the color-change allows access to(Z)-1;2-dialkyl alkenes with very high efficiency;exquisite precision;and broad functional group tolerance.The reliability and practicability of this protocol is demonstrated by cis-semihydrogenation of complex polyfunctionalized bioactive molecules.Mechanistic studies establish that the propensity of(PCC_(NHC))Ir to undergo facile EtOH decarbonylation to form isomerization-inactive species(PCC_(NHC))IrHMe(CO)only when the semihydrogenation reaction is completed is important to stereo-and chemoselectivity control.
基金supported by the National Key Research and Development Program of China(No.2021YFA1500900)the National Natural Science Foundation of China(No.52071174)the Natural Science Foundation of Jiangsu Province,Major Project(No.BK20212005).
文摘Semihydrogenation of trace acetylene in an ethylene gas stream is a vital step for the industrial production of polyethylene,in which Pd single-site catalysts(SSCs)have great potential.Herein,two Pd SSCs with different coordination structures are prepared on hierarchical nitrogen-doped carbon nanocages(hNCNC)by regulating the nitrogen species with or without using dicyandiamide.With using dicyandiamide,the obtained Pd1-Ndicy/hNCNC SSC features the coordinated Pd by two pyridinic N and two pyrrolic N(PdN^(py)_(2)N^(pr)_(2)).Without using dicyandiamide,the obtained Pd1/hNCNC SSC features the coordinated Pd by pyridinic N and C(PdN^(py_(x)C_(4-x)),x=1-4).The former exhibits an 18-fold increase in catalytic activity compared to the latter.Theoretical results reveal the abundant unoccupied orbital states above the Fermi level of moiety,which can facilitate the activation of substrate molecules and dynamics of acetylene hydrogenation as supported by the combined theoretical and experimental results.In addition,PdN^(py)_(2)N^(pr)_(2)the moiety presents a favorable desorption of ethylene.Consequently,the Pd1-Ndicy/hNCNC SSC exhibits high C2H2 conversion(99%)and C2H4 selectivity(87%)at 160℃.This study demonstrates the impact of Pd single-site coordination structure on catalytic performance,which is significant for the rational design of advanced Pd SSCs on carbon-based supports.
基金supported by the National Natural Science Foundation of China(Nos.22475170,52101271,22375166)the Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515111017,2024A1515011977)the Key Research and Development Program of Shaanxi Province(No.2024GX-YBXM379)。
文摘Molecular catalysts can effectively steer the electrocatalytic acetylene semihydrogenation into ethylene,but realizing high Faradaic efficiency(FE)at industrial current densities remains a challenge.Herein,we report a ligand engineering strategy that utilizes polymeric N–heterocyclic carbene(NHC)as a hydrophobic ligand to modulate the microenvironment of Cu sites.This polymeric NHC imparts appropriate hydrophobic properties for the chelated Cu sites,thereby moderating the H_(2)O transport and enabling easy access of acetylene.Consequently,the polymeric NHC chelated Cu exhibits an FE_(ethylene)of~97%at a current density of 500 m A/cm^(2)in a flow cell.Particularly in a zero-gap reactor,the FE_(ethylene)consistently exceeds 86%across current densities from 100 m A/cm^(2)to 400 m A/cm^(2),reaching an optimal FEethyleneof 98%at 200 m A/cm^(2)and achieving durable operation for 155 h at 100 m A/cm^(2).This work provides a promising paradigm to regulate the microenvironment of molecular catalysts for improving electrocatalytic performances under industrial current densities.
基金supported by the National Natural Science Foundation of China(22005245,52101271)the Fundamental Research Funds for the Central Universities(G2022KY0606,G2020KY05306,G2022KY05111)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2020A1515111017)the Natural Science Foundation of Shaanxi Province(2021JQ-094)the fellowship of China Postdoctoral Science Foundation(2021M692619)
文摘Selective semihydrogenation of acetylene in raw olefin streams to ethylene is a key industrial reaction to produce polymer-grade feeds for the manufacture of corresponding polymers.The currently used process in industry is the thermocatalytic acetylene semihydrogenation with pressurized hydrogen and Pd-based catalysts at relatively high temperatures.The high cost of Pd urgently desires the design of non-noble metal-based catalysts.However,non-noble metal-based catalysts commonly require much higher reaction temperatures than Pd-based catalysts because of their poor intrinsic activity.Therefore,aiming at increasing economic efficiency and sustainability,various strategies are explored for developing non-noble metal-based catalysts for thermocatalytic and green acetylene semihydrogenation processes.In this review,we systematically summarize the recent advances in catalytic technology from thermocatalysis to sustainable alternatives,as well as corresponding regulation strategies for designing high-performance non-noble metal-based catalysts.The crucial factors affecting catalytic performance are discussed,and the fundamental structure-performance correlation of catalysts is outlined.Meanwhile,we emphasize current challenging issues and future perspectives for acetylene semihydrogenation.This review will not only promote the rapid exploration of non-noble metal-based catalysts for acetylene semihydrogenation,but also advance the development of sustainable processes like electrocatalysis and photocatalysis.
文摘The promoting effect of sulfur sources is an intriguing but poorly understood phenomenon. Herein, we studied the treatment of PdCu bimetallic nanoparticles （NPs） with different amounts of sulfur powder. Low-level sulfidation led to the generation of a Pd30CuloS9 NP catalyst consisting of surface enriched Pd NPs, electron deficient Pd and Cu, as well as zero valence sulfur. The Pd30CuloS9 NP catalyst showed pronouncedly enhanced activity and selectivity in the semihydrogenation of alkynes. Our study revealed for the first time a possible cause for the promoting effect of sulfur at the atomic level, suggesting a new strategy in catalyst design.
基金This work was supported by the National Key Research and Development Program of China(2017YFA0207302 and 2017YFA0207303)the National Natural Science Foundation of China(21890752,21731005,21420102001,21573178,and 91845102)the Fundamental Research Funds for Central Universities(20720180026).
文摘Atomically dispersed catalysts have demonstrated superior catalytic performance in many chemical transformations.However,limited success has been achieved in applying oxide-supported atomically dis-persed catalysts to semihydrogenation of alkynes under mild conditions.
基金We thank the financial supports from the National Natural Science Foundation of China(No.21576243)the Natural Science Foundation of Zhejiang Province(Nos.LY18B060006,LY17B060001,and LY21B030003).
文摘Enhancing the selectivity of noble metal catalysts through electronic modulation is important for academic research and chemical industrial processes.Herein,we report a facile sacrificial template strategy for the synthesis of PdZn intermetallic compound(3-4 nm)highly distributed in ZnO/nitrogen-decorated carbon hollow spheres(PdZn-ZnO/NCHS)to optimize the selectivity of Pd catalysts,which involves carbonization of a core-shell structured polystyrene(PS)@ZIF-8 precursor in an inert atmosphere,impregnation Pd precursor,and subsequent H2 reduction treatment.Due to the unique structural and compositional features,the developed PdZn-ZnO/NCHS delivers an excellent catalytic performance for the semihydrogenation of 2-methyl-3-butyn-2-ol(MBY)to 2-methyl-3-buten-2-ol(MBE)with high activity(>99%),high selectivity(96%),and good recyclability,outperforming the analog Pd on ZnO(Pd/ZnO)as well as the supported Pd nanoparticles(Pd/C and Pd/NC).Density functional theory(DFT)calculations reveal that the presence of Znδ+species in PdZn-ZnO/NCHS alters the adsorption modes of reactant and product,leading to a decrease of the adsorption strength and an enhancement of the energy barrier for overhydrogenation,which results in a kinetic favor for the selective transformation of MBY to MBE.In addition,PdZn-ZnO/NCHS was also very effective for the partial hydrogenation of dehydrolinalool to hydrolinalool.
基金financially supported by the National Natural Science Foundation of China(22005245 and 22201232)the Key Research and Development Program of Shaanxi Province(2023-YBGY-284)+3 种基金the Fundamental Research Funds for the Central Universities(G2022KY0606 and G2022KY05114)the Synergy Innovation Foundation of the University and Enterprise for Graduate Students in Northwestern Polytechnical University(CX2021037 and CX2022074)the Fundamental Research Funds for China Postdoctoral Science Foundation(BX2021247 and 2021M692635)the Natural Science Foundation of Shaanxi Province(2022JQ-083).
文摘Alkenols are important intermediates for the industrial manufacture of various commodities and fine chemicals.At present,alkenols are produced via thermocatalytic semihydrogenation of corresponding alkynols using precious metal Pd-based catalysts in pressurized hydrogen atmosphere.In this work,we highlight an efficient electrocatalytic strategy for selectively reducing alkynols to alkenols under ambient conditions.Using 2-methyl-3-butyn-2-ol as a model alkynol,Cu3P nanoarrays anchored on Cu foam remarkably deliver an industrial-level partial current density of 0.79 A·cm^(-2) and a specific selectivity of 98%for 2-methyl-3-buten-2-ol in acidic solution.Over a 40-runs stability test,Cu3P nanoarrays maintain 90%alkynol conversion and 90%alkenol selectivity.Even in a large two-electrode flow electrolyser,the single-pass alkynol conversion and alkenol selectivity of Cu3P nanoarrays exceed 90%.Moreover,this selective electrocatalytic hydrogenation approach is broadly feasible for the production of various water-soluble alkenols.Electrochemical analyses,theoretical simulation and electrochemical in-situ infrared investigations together reveal that exothermic alkynol hydrogenation,facile alkenol desorption and formation of active H on Cu3P surfaces account for the excellent electrocatalytic performance.
基金supported by the National University of Singapore Flagship Green Energy Program (#R-279-000-553-646 and R-279-000-553-731)the National Natural Science Foundation of China (21908085)the Natural Science Foundation of Jiangsu Province,China (BK20190961)
文摘Combining the advantages of both heterogeneous and homogeneous catalysts,single-atom catalysts(SACs)with unique electronic properties have shown excellent catalytic properties.Herein,we report single-atom Pd dispersed on nanoscale TiO2 prepared by self-assembly method as efficient and selective catalysts for the hydrogenation of phenylacetylene to styrene.The catalysts were characterized by N2 adsorption/desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and X-ray absorption spectroscopy(XAS).0.2 Pd-TiO2(150℃)possessing dominant single-atom Pd species,exhibited a turnover frequency(TOF)of over 8000 h^-1 with 91%selectivity towards styrene at room temperature.Further increasing Pd loading from 0.2%to 0.5%and 1.5%resulted in the decrease of activity probably due to the formation of Pd nanoparticles.Besides,the 0.2 Pd-TiO2 prepared by self-assembly strategy showed better catalytic performance than commercial 10%Pd/C and0.2 Pd-TiO2 synthesized by using impregnation method.
基金support from the National Key Research and Development Program of China(No.2018YFA0702001)the National Natural Science Foundation of China(No.22071225)+1 种基金the Fundamental Research Funds for the Central Universities(No.WK2060190103)the Joint Funds from Hefei National Synchrotron Radiation Laboratory(No.KY2060000175).
文摘Modulation of geometric and electronic structures of supported Pd-based catalysts by forming atomically ordered intermetallic phases enables an effective way to optimize catalytic performance.However,the synthesis of small-sized Pd-based intermetallic nanoparticle catalysts with improved mass-based activity remains formidable challenges,since high-temperature annealing generally required for atom ordering inevitably leads to severe metal sintering and thus large crystallites.Here,we present a bulky nanodiamond-confined method to prepare sub-5 nm Pd_(3)Pb intermetallic nanocatalysts by mitigating metal sintering at high temperatures,which is induced by the electronic interactions between metal and defect-rich graphene shells reinforced by diamond cores in the bulky nanodiamond support.The prepared small-sized Pd_(3)Pb intermetallic catalyst displays a high activity with a turnover frequency of 932 h−1 for the semihydrogenation of phenylacetylene under mild conditions(room temperature,3 bar H_(2)),along with a high selectivity of>96%to styrene near the complete conversion of phenylacetylene.
基金This work was supported by the Fundamental Research Funds for the Natural Science Foundation of Shaanxi Province(nos.2020JQ-141 and 2021JQ-094)the National Natural Science Foundation of China(nos.22005245 and 52101271)+1 种基金the National Key Research and Development Program of China(no.SQ2021YFE010191)the Startup Fund(no.D5000210090)of Northwestern Polytechnical University.
文摘Owing to serious poison of downstream olefin polymerization catalysts from acetylene impurities,selective reduction of acetylene to ethylene is a pivotal process in petrochemical industry.However,during thermocatalytic and electrocatalytic acetylene semihydrogenation,acetylene C-C coupling inevitably occurs on current catalysts.The resultant oligomeric species(particularly long-chain hydrocarbons)block active sites and mass transportation,and eventually decrease catalytic activity and stability.In this work,we report Ag nanowires(NWs)as high-performance electrocatalysts for acetylene semihydrogenation,where the C-C coupling is unprecedentedly suppressed by weakening acetylene adsorption.In pure acetylene,1,3-butadiene Faradaic efficiency(FE)of Ag NWs is only 2.1%,which is far lower than 41.2%for Cu nanoparticles at−0.2 V versus reversible hydrsogen electrode.Ethylene partial current density of Ag NWs reaches 217 mA/cm^(2)at 0.85 V,which is considerably higher than those for state-of-the-art Cu-based electrocatalysts.Markedly,no 1,3-butadiene is produced on Ag NWs in a large two-electrode flow cell fed with crude ethylene containing 1 vol%acetylene,presenting thorough termination of acetylene C-C coupling.In situ electrochemical Raman spectroscopy and theoretical investigations reveal that weak acetylene adsorption on Ag surfaces is intrinsically responsible for prohibiting their oligomerization.This work will spark the rapid development of high-performance and stable electrocatalysts for reducing alkynes to olefins.
基金supported by the US National Science Foundation(grant no.CHE-2102363).
文摘Catalytic hydrogenation is a foundational pillar of the chemical industry.Especially,semi-hydrogenation of acetylene(C_(2)H_(2))to ethylene(C_(2)H_(4))is an important industrial reaction to generate polymer-grade C_(2)H_(4) from crude streams for polyethylene production.The industrial C_(2)H_(2) semi-hydrogenation process is currently dominated by the thermocatalytic route that involves cost-prohibitive Pdbased catalysts,high operation temperature,and excess hydrogen feed.Thermocatalytic semi-hydrogenation of C_(2)H_(2) is also hindered by limited C_(2)H_(4) selectivity due to unwanted over-hydrogenation.Therefore,seeking strategies to improve the catalyst performance while reducing energy consumption and capital expenditure of the current hydrogenation schemes is essential to the petrochemical industry.Fortunately,recent advances in electrocatalytic C_(2)H_(2) semi-hydrogenation systems lead to a sustainable alternative to traditional thermocatalytic systems.Using renewable electricity as an energy source and water as a hydrogen source,electrocatalytic systems can operate under ambient conditions with tunable selectivity toward C_(2)H_(4).In this review,we first discuss the reactor design for electrocatalytic C_(2)H_(2) semi-hydrogenation.We then review the computational studies for understanding and predicting the catalytic behavior ofmetal catalysts.We also summarize advanced electrocatalysts categorized into Cu-based and non-Cu-based materials.Finally,we provide perspectives on the opportunities to overcome existing challenges for future practical application of electrocatalytic C_(2)H_(2) semihydrogenation.
