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
Photocatalytic semihydrogenation of coal-derived acetylene using water as a hydrogen source under ambient conditions offers a sustainable and petroleum-independent route for ethylene production,yet suffers from the ut...Photocatalytic semihydrogenation of coal-derived acetylene using water as a hydrogen source under ambient conditions offers a sustainable and petroleum-independent route for ethylene production,yet suffers from the utilization of expensive photosensitizers,weak acetylene adsorption and insufficient generation of active hydrogen(H^(*)).Herein,we fabricate a Co single-atom catalyst anchored on nitrogen-vacancy-rich carbon nitride(Co/C_(3)N_(4)-V_(N))via in-situ co-polymerization.Owing to enhanced light absorption and charge separation efficiency,the Co/C_(3)N_(4)-V_(N) exhibits a considerably high ethylene production rate of 3916.5μmol·gcat^(-1)·h^(-1)under 420 nm light-emitting diode(LED)illumination without photosensitizers,surpassing bulk C_(3)N_(4)by 53-folds and outperforming previously reported photocatalysts.The photocatalytic experiments,acetylene temperature-programmed desorption analysis,in-situ photo-chemical infrared spectra and theoretical simulations together reveal that N vacancies and Co single atoms in Co/C_(3)N_(4)-V_(N) synergistically promote the acetylene adsorption,H^(*)generation from water dissociation and acetylene hydrogenation,thereby accelerating the kinetics of photocatalytic acetylene semihydrogenation.展开更多
Imidazolyl amino cuboidal Mo_(3)(μ_(3)-S)(μ-S)_(3)clusters have been investigated as catalysts for the semihydrogenation of alkynes.For that purpose,three new air-stable cluster salts[Mo_(3)S_(4)Cl_(3)(ImNH_(2))_(3)...Imidazolyl amino cuboidal Mo_(3)(μ_(3)-S)(μ-S)_(3)clusters have been investigated as catalysts for the semihydrogenation of alkynes.For that purpose,three new air-stable cluster salts[Mo_(3)S_(4)Cl_(3)(ImNH_(2))_(3)]BF_(4)([1]BF_(4)),[Mo_(3)S_(4)Cl_(3)(ImNH(CH_(3)))_(3)]BF_(4)([2]BF_(4))and[Mo_(3)S_(4)Cl_(3)(ImN(CH_(3))_(2))_(3)]BF_(4)([3]BF_(4))have been isolated in moderate to high yields and fully characterized.Crystal structures of complexes[1]PF6 and[2]Cl confirm the formation of a single isomer in which the nitrogen atoms of the three imidazolyl groups of the ligands are located trans to the capping sulfur atom which leaves the three bridging sulfur centers on one side of the trimetallic plane while the amino groups lie on the opposite side.Kinetic studies show that the cluster bridging sulfurs react with diphenylacetylene(dpa)in a reversible equilibrium to form the corresponding dithiolene adduct.Formation of this adduct is postulated as the first step in the catalytic semihydrogenation of alkynes mediated by molybdenum sulfides.These complexes catalyze the(Z)-selective semihydrogenation of diphenylacetylene(dpa)under hydrogen in the absence of any additives.The catalytic activity lowers sequentially upon replacement of the hydrogen atoms of the N-H_(2)moiety in 1+without reaching inhibition.Mechanistic experiments support a sulfur centered mechanism without participation of the amino groups.Different diphenylacetylene derivatives are selectively hydrogenated using complex 1+to their corresponding Z-alkenes in excellent yields.Extension of this protocol to 3,7,11,15-tetramethylhexadec-1-yn-3-ol,an essential intermediate for the production of vitamin E,affords the semihydrogenation product in very good yield.展开更多
Herein we report the application of a Co(II)PNN^(H) pincer catalyst system(PNN^(H)=2-(5-(t-butyl)-1Hpyrazol-3-yl)-6-(dialkylphosphinomethyl)pyridine)for the highly E-selective transfer semihydrogenation of internal di...Herein we report the application of a Co(II)PNN^(H) pincer catalyst system(PNN^(H)=2-(5-(t-butyl)-1Hpyrazol-3-yl)-6-(dialkylphosphinomethyl)pyridine)for the highly E-selective transfer semihydrogenation of internal diaryl alkynes using methanol and ammonia borane as hydrogen donors.The catalyst system is highly active(short reaction times,low Co concentration)and operates at very mild conditions(low temperature and transfer hydrogenation conditions).Spectroscopic and computational studies suggest that catalysis occurs via the Co(II)oxidation state,most likely with a Co(II)hydride as the key intermediate.Computational analysis of the reaction mechanism further rationalises the selective formation of E-alkenes and the absence of overreduction to produce alkanes.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
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
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
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
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
The development of recyclable metal-free catalysts has become a longstanding goal owing to their green,economical,and available merits.In this work,we proposed a strategy of constructing a solid frustrated Lewis pair(...The development of recyclable metal-free catalysts has become a longstanding goal owing to their green,economical,and available merits.In this work,we proposed a strategy of constructing a solid frustrated Lewis pair(FLP)catalyst through stepwise functionalization of conjugated microporous polymer(CMP).Importantly,this metal-free solid FLP catalyst exhibited considerable activity and selectivity in the semihydrogenation of phenylacetylene to styrene alongside notable stability and recyclability.The structure-activity relationship(SAR)of solid FLP catalysts was elucidated by experiment and calculation.Our work not only introduces a novel approach for constructing stable FLP sites on solid supports but also enriches the application of metal-free main group for practical and substantial catalytic transformations.展开更多
Facile reactant dissociation and weakly bound intermediates are essential for achieving both efficient and selective catalysis.However,these two factors are inherently interconnected,making their simultaneous optimiza...Facile reactant dissociation and weakly bound intermediates are essential for achieving both efficient and selective catalysis.However,these two factors are inherently interconnected,making their simultaneous optimization particularly challenging.Herein,we propose a decoupling strategy to circumvent this limitation and demonstrate it using a novel antenna-reactor catalyst constructed with single atom and plasmonic nanoparticles.By combining in situ surface-enhanced Raman spectroscopy with density functional theory calculations,we reveal that nonequilibrium carriers significantly enhance hydrogen dissociation at Pd single-atom sites.Subsequently,these active hydrogen atoms spillover to adjacent Au surfaces,facilitating more favorable alkyne hydrogenation and alkene desorption processes.Consequently,the Pd SAC-Au photocatalyst exhibits remarkable catalytic performance,achieving a turnover frequency value of 3964 mol C=C mol Pd^(-1) h^(-1) and demonstrating 99.99% conversion of phenylacetylene with 90% selectivity toward styrene under mild reaction conditions(298 K,101.3 kPa).This approach offers a novel pathway to overcome traditional catalytic trade-off,highlighting the potential for designing high-performance single-atom catalysts for chemical reactions.展开更多
Electrochemical semihydrogenation of acetylene(C_(2)H_(2))using renewable electricity offers a sustainable route for ethylene(C_(2)H_(4))production.However,the development of this technique has been hindered by many c...Electrochemical semihydrogenation of acetylene(C_(2)H_(2))using renewable electricity offers a sustainable route for ethylene(C_(2)H_(4))production.However,the development of this technique has been hindered by many challenges,such as competitive hydrogen evolution reactions(HERs)and overhydrogenation at high current densities,which will reduce the faradaic efficiency(FE)of C_(2)H_(4) and negatively impact downstream processing.Herein,we develop defectrich copper nanocubes(v-Cu NCs)as efficient electrocatalysts that facilitateC_(2)H_(4) adsorption while suppressing HER and overhydrogenation.The superior semihydrogenation performances are verified by the high C_(2)H_(4) FE of 98.3%at an ultrahigh current density of 0.7 A cm^(−2).Remarkably,in a 25 cm^(2) electrolyzer,v-Cu NCs deliver a record-high single-pass conversion of 97.5%forC_(2)H_(4) and C_(2)H_(4) selectivity of 97.4%at a cathode current of 1.6 A with a flow rate of 10 mL min−1,operating stably for 50 h.In-situ Raman spectroscopy and theoretical calculations reveal that uniformly oriented Cu(100)planes and nitrogen vacancies generate strongC_(2)H_(4) adsorption at copper sites,which facilitates hydrogenation kinetics and increases the energy barrier for overhydrogenation.This work offers valuable insights into the implementation ofC_(2)H_(4)-to-C_(2)H_(4) production and the development of efficient electrocatalysts forC_(2)H_(4) semihydrogenation.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
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.
基金supported by the National Key Research and Development Program of China(2024YFA1510100)the National Natural Science Foundation of China(52373308,22005245,12374019,12235011)+1 种基金the Key Research and Development Program of Shaanxi Province(2023-YBGY-284)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2022074).
文摘Photocatalytic semihydrogenation of coal-derived acetylene using water as a hydrogen source under ambient conditions offers a sustainable and petroleum-independent route for ethylene production,yet suffers from the utilization of expensive photosensitizers,weak acetylene adsorption and insufficient generation of active hydrogen(H^(*)).Herein,we fabricate a Co single-atom catalyst anchored on nitrogen-vacancy-rich carbon nitride(Co/C_(3)N_(4)-V_(N))via in-situ co-polymerization.Owing to enhanced light absorption and charge separation efficiency,the Co/C_(3)N_(4)-V_(N) exhibits a considerably high ethylene production rate of 3916.5μmol·gcat^(-1)·h^(-1)under 420 nm light-emitting diode(LED)illumination without photosensitizers,surpassing bulk C_(3)N_(4)by 53-folds and outperforming previously reported photocatalysts.The photocatalytic experiments,acetylene temperature-programmed desorption analysis,in-situ photo-chemical infrared spectra and theoretical simulations together reveal that N vacancies and Co single atoms in Co/C_(3)N_(4)-V_(N) synergistically promote the acetylene adsorption,H^(*)generation from water dissociation and acetylene hydrogenation,thereby accelerating the kinetics of photocatalytic acetylene semihydrogenation.
基金support of the Spanish Ministerio de Economía y Competitividad(grants PRE2019-088511,and PID2019-107006GB-C22)Generalitat Valenciana(grant CIAICO/2021/122)Universitat Jaume I(grants UJI-B2019-30,UJI-B2021-29 and UJI-B2022-56)is gratefully acknowledged.
文摘Imidazolyl amino cuboidal Mo_(3)(μ_(3)-S)(μ-S)_(3)clusters have been investigated as catalysts for the semihydrogenation of alkynes.For that purpose,three new air-stable cluster salts[Mo_(3)S_(4)Cl_(3)(ImNH_(2))_(3)]BF_(4)([1]BF_(4)),[Mo_(3)S_(4)Cl_(3)(ImNH(CH_(3)))_(3)]BF_(4)([2]BF_(4))and[Mo_(3)S_(4)Cl_(3)(ImN(CH_(3))_(2))_(3)]BF_(4)([3]BF_(4))have been isolated in moderate to high yields and fully characterized.Crystal structures of complexes[1]PF6 and[2]Cl confirm the formation of a single isomer in which the nitrogen atoms of the three imidazolyl groups of the ligands are located trans to the capping sulfur atom which leaves the three bridging sulfur centers on one side of the trimetallic plane while the amino groups lie on the opposite side.Kinetic studies show that the cluster bridging sulfurs react with diphenylacetylene(dpa)in a reversible equilibrium to form the corresponding dithiolene adduct.Formation of this adduct is postulated as the first step in the catalytic semihydrogenation of alkynes mediated by molybdenum sulfides.These complexes catalyze the(Z)-selective semihydrogenation of diphenylacetylene(dpa)under hydrogen in the absence of any additives.The catalytic activity lowers sequentially upon replacement of the hydrogen atoms of the N-H_(2)moiety in 1+without reaching inhibition.Mechanistic experiments support a sulfur centered mechanism without participation of the amino groups.Different diphenylacetylene derivatives are selectively hydrogenated using complex 1+to their corresponding Z-alkenes in excellent yields.Extension of this protocol to 3,7,11,15-tetramethylhexadec-1-yn-3-ol,an essential intermediate for the production of vitamin E,affords the semihydrogenation product in very good yield.
基金support by the DFG(project code 419924354)is gratefully acknowledged.
文摘Herein we report the application of a Co(II)PNN^(H) pincer catalyst system(PNN^(H)=2-(5-(t-butyl)-1Hpyrazol-3-yl)-6-(dialkylphosphinomethyl)pyridine)for the highly E-selective transfer semihydrogenation of internal diaryl alkynes using methanol and ammonia borane as hydrogen donors.The catalyst system is highly active(short reaction times,low Co concentration)and operates at very mild conditions(low temperature and transfer hydrogenation conditions).Spectroscopic and computational studies suggest that catalysis occurs via the Co(II)oxidation state,most likely with a Co(II)hydride as the key intermediate.Computational analysis of the reaction mechanism further rationalises the selective formation of E-alkenes and the absence of overreduction to produce alkanes.
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 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 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 Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDB36000000,Z.Y.T.)the National Key R&D Program of China(grant nos.2021YFA1200302 and 2022YFA1205400,Z.Y.T.)the National Natural Science Foundation of China(grant nos.92356304 and 92056204,Z.Y.T.).
文摘The development of recyclable metal-free catalysts has become a longstanding goal owing to their green,economical,and available merits.In this work,we proposed a strategy of constructing a solid frustrated Lewis pair(FLP)catalyst through stepwise functionalization of conjugated microporous polymer(CMP).Importantly,this metal-free solid FLP catalyst exhibited considerable activity and selectivity in the semihydrogenation of phenylacetylene to styrene alongside notable stability and recyclability.The structure-activity relationship(SAR)of solid FLP catalysts was elucidated by experiment and calculation.Our work not only introduces a novel approach for constructing stable FLP sites on solid supports but also enriches the application of metal-free main group for practical and substantial catalytic transformations.
基金the financial support from the National Key R&D Program(2021YFB4000600)the National Natural Science Foundation of China(22574082)+1 种基金the 111 project(B12015)the Haihe Laboratory of Sustainable Chemical Transformations,and the Princess Nourah bint Abdulrahman University Researchers Supporting Project(PNURSP2025R18).
文摘Facile reactant dissociation and weakly bound intermediates are essential for achieving both efficient and selective catalysis.However,these two factors are inherently interconnected,making their simultaneous optimization particularly challenging.Herein,we propose a decoupling strategy to circumvent this limitation and demonstrate it using a novel antenna-reactor catalyst constructed with single atom and plasmonic nanoparticles.By combining in situ surface-enhanced Raman spectroscopy with density functional theory calculations,we reveal that nonequilibrium carriers significantly enhance hydrogen dissociation at Pd single-atom sites.Subsequently,these active hydrogen atoms spillover to adjacent Au surfaces,facilitating more favorable alkyne hydrogenation and alkene desorption processes.Consequently,the Pd SAC-Au photocatalyst exhibits remarkable catalytic performance,achieving a turnover frequency value of 3964 mol C=C mol Pd^(-1) h^(-1) and demonstrating 99.99% conversion of phenylacetylene with 90% selectivity toward styrene under mild reaction conditions(298 K,101.3 kPa).This approach offers a novel pathway to overcome traditional catalytic trade-off,highlighting the potential for designing high-performance single-atom catalysts for chemical reactions.
基金supported by the National Natural Science Foundation of China(grant nos.22322807,22168023,22268029,and 22108243)the Natural Science Foundation of Jiangxi Province(grant no.20224ACB204003)+1 种基金the China Scholarship Council(grant no.202206820025)the Australian Research Council(ARC)through the ARC Discovery project(grant no.DP230101579).
文摘Electrochemical semihydrogenation of acetylene(C_(2)H_(2))using renewable electricity offers a sustainable route for ethylene(C_(2)H_(4))production.However,the development of this technique has been hindered by many challenges,such as competitive hydrogen evolution reactions(HERs)and overhydrogenation at high current densities,which will reduce the faradaic efficiency(FE)of C_(2)H_(4) and negatively impact downstream processing.Herein,we develop defectrich copper nanocubes(v-Cu NCs)as efficient electrocatalysts that facilitateC_(2)H_(4) adsorption while suppressing HER and overhydrogenation.The superior semihydrogenation performances are verified by the high C_(2)H_(4) FE of 98.3%at an ultrahigh current density of 0.7 A cm^(−2).Remarkably,in a 25 cm^(2) electrolyzer,v-Cu NCs deliver a record-high single-pass conversion of 97.5%forC_(2)H_(4) and C_(2)H_(4) selectivity of 97.4%at a cathode current of 1.6 A with a flow rate of 10 mL min−1,operating stably for 50 h.In-situ Raman spectroscopy and theoretical calculations reveal that uniformly oriented Cu(100)planes and nitrogen vacancies generate strongC_(2)H_(4) adsorption at copper sites,which facilitates hydrogenation kinetics and increases the energy barrier for overhydrogenation.This work offers valuable insights into the implementation ofC_(2)H_(4)-to-C_(2)H_(4) production and the development of efficient electrocatalysts forC_(2)H_(4) semihydrogenation.
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.
