The dehydrogenation of alkanes has emerged as a vital complementary process to address the increasing global demand for olefins.A key challenge remains in the construction of novel active centers that offer superior a...The dehydrogenation of alkanes has emerged as a vital complementary process to address the increasing global demand for olefins.A key challenge remains in the construction of novel active centers that offer superior activity,stability,and cost-effectiveness.Herein,tricoordinated cobalt atoms were successfully fabricated through an in-situ ligand-protected synthesis by introducing tungsten atoms into zeolite frameworks.These unsaturated Co species efficiently activate C-H bonds while suppressing C-C bond cleavage,resulting in exceptional catalytic activity and olefin selectivity in both propane and ethane dehydrogenation reactions.The optimized Co_(0.2%)@0.01W-S-1 catalyst demonstrated an impressive propylene formation rate of 15.2 molC_(3H6)gcC h^(-1)at 823 K and an ethylene formation rate of 240.3mol_(C2H4)g_(Co)^(-1)h^(-1)at 913 K,with propylene and ethylene selectivities of 99.0%and 97.5%,respectively.These results not only significantly surpass conventional tetracoordinated Co catalysts but also rival some Pt-based catalysts under similar conditions.Importantly,the catalyst exhibited excellent stability in dehydrogenation reactions,with no significant loss in catalytic activity after five consecutive regeneration cycles.This work offers valuable insights into the design of zeolite-supported non-precious metal catalysts with high activity and durability for efficient alkane dehydrogenation.展开更多
Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally ...Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally friendly and cost-effective alternatives.In this study,we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co_(1)O_(3)H_(x) structure by regulating silanol nests in purely siliceous Beta zeolites.Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity.Additionally,the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles.Notably,the optimized Co_(0.3%)/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_(C3H6) g_(cat)^(-1) h^(-1),with an exceptional propylene selectivity of 99.1%at 550℃.Moreover,the Co_(0.3%)/deAl-meso-Beta catalyst demonstrated excellent stability,with negligible deactivation after 5 consecutive regeneration cycles.This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites,providing valuable insights for the design of high-activity,high-stability,and low-cost PDH catalysts.展开更多
Zeolite-encapsulated Pt-based alloy catalysts exhibit exceptional activity and sintering resistance in propane dehydrogenation(PDH).However,their preparation generally relies on the ligand-protected hydrothermal synth...Zeolite-encapsulated Pt-based alloy catalysts exhibit exceptional activity and sintering resistance in propane dehydrogenation(PDH).However,their preparation generally relies on the ligand-protected hydrothermal synthesis method,which suffers from high cost,organic pollution,and low metal utilization,thereby limiting their large-scale preparation and application.Here,we developed a post-treatment strategy based on metal replacement reaction to form subnanometer PtCu alloy in Cu-exchanged zeolite.Copper cations(Cu^(2+) )were first introduced into ZSM-5(MFI)via ion exchange,followed by reduction to form Cu^(0)/Cu^(+) nanoparticles(CuO_(x))inside the zeolite.Subsequently,Pt^(2+) ions were incorporated to form PtCu alloy supported on CuO_(x) nanoparticles via a metal replacement reaction.The as-prepared PtCu5@MFI-K(Pt/Cu=1/5)achieved 49.7%propane conversion with>90%propylene selectivity alongside excellent regeneration stability.The forward rate constant(k_(f))of PtCu5@MFI-K at 550℃ reached 868 molC3H6 gPt^(−1) h^(−1) bar^(−1),which was higher than that of previously reported zeolite-encapsulated Pt-based catalysts.Significantly,Pt and Cu species could dynamically recombine to form PtCu alloy during the regeneration process,showing excellent sinterresistant ability of PtCu5@MFI-K.This work presents a facile,simple,and cost-effective strategy for preparing alloy@zeolite catalysts with tailored metal compositions for important catalytic reactions.展开更多
Metal-containing crystalline porous materials(CPMs)are gaining popularity in heterogeneous catalysis because of their highly crystalline and porous systems,and their excellent chemical tunability.Modification of the m...Metal-containing crystalline porous materials(CPMs)are gaining popularity in heterogeneous catalysis because of their highly crystalline and porous systems,and their excellent chemical tunability.Modification of the metal species and framework structure permits them to have greater activity,selectivity,and stability over other materials.An in-depth understanding of the complex nature of metal active sites in CPMs is essential for revealing the structure-performance relationships and directing the rational design of such catalysts.Compared to conventional characterization techniques,the rapid development of X-ray absorption spectroscopy(XAS)has provided element-and site-specific deep insights into the electronic and structural information of metal species in CPMs.As such,this review begins by summarizing novel XAS techniques and analysis methods in accurately obtaining such data.Next,the combination of XAS with other high-level characterization methods into disclosing the configuration of active sites in metalcontaining CPMs is presented.Then,the utilization of theory-assisted XAS data analysis in examining complex metal-containing CPM catalysts is discussed.Afterwards,advanced in-situ/operando XAS studies into revealing the working sites in metal-containing CPMs under catalytic conditions are highlighted.We conclude by outlining the future challenges and prospects of XAS measurements,data analyses,and in-situ/operando setups in advancing the study of metal-in-CPM catalysts.展开更多
基金supported by the National Key R&D Program of China(Grant No.2022YFA1506000)Gusu Innovation and Entrepreneurship Leading Talents Program(ZXL2022497)+5 种基金Jiangsu Distinguished Professor programfinancial support by National Natural Science Foundation of China(Grant No.22301057)Natural Science Foundation of Hebei Province(Grant No.B2023201065)Science Research Project of Hebei Education Department(Grant No.BJK2024103)supported by the Open Research Fund of Shanghai Key Laboratory of High-resolution Electron MicroscopyOpen Project of State Key Laboratory of Supramolecular Structure and Materials(sklssm2024019),ShanghaiTech University。
文摘The dehydrogenation of alkanes has emerged as a vital complementary process to address the increasing global demand for olefins.A key challenge remains in the construction of novel active centers that offer superior activity,stability,and cost-effectiveness.Herein,tricoordinated cobalt atoms were successfully fabricated through an in-situ ligand-protected synthesis by introducing tungsten atoms into zeolite frameworks.These unsaturated Co species efficiently activate C-H bonds while suppressing C-C bond cleavage,resulting in exceptional catalytic activity and olefin selectivity in both propane and ethane dehydrogenation reactions.The optimized Co_(0.2%)@0.01W-S-1 catalyst demonstrated an impressive propylene formation rate of 15.2 molC_(3H6)gcC h^(-1)at 823 K and an ethylene formation rate of 240.3mol_(C2H4)g_(Co)^(-1)h^(-1)at 913 K,with propylene and ethylene selectivities of 99.0%and 97.5%,respectively.These results not only significantly surpass conventional tetracoordinated Co catalysts but also rival some Pt-based catalysts under similar conditions.Importantly,the catalyst exhibited excellent stability in dehydrogenation reactions,with no significant loss in catalytic activity after five consecutive regeneration cycles.This work offers valuable insights into the design of zeolite-supported non-precious metal catalysts with high activity and durability for efficient alkane dehydrogenation.
文摘Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally friendly and cost-effective alternatives.In this study,we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co_(1)O_(3)H_(x) structure by regulating silanol nests in purely siliceous Beta zeolites.Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity.Additionally,the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles.Notably,the optimized Co_(0.3%)/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_(C3H6) g_(cat)^(-1) h^(-1),with an exceptional propylene selectivity of 99.1%at 550℃.Moreover,the Co_(0.3%)/deAl-meso-Beta catalyst demonstrated excellent stability,with negligible deactivation after 5 consecutive regeneration cycles.This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites,providing valuable insights for the design of high-activity,high-stability,and low-cost PDH catalysts.
基金the National Key Research and Development Program of China(grant no.2021YFA1501202)the National Natural Science Foundation of China(grant no.22288101)the“111 center”(grant no.B17020)for supporting this work.
文摘Zeolite-encapsulated Pt-based alloy catalysts exhibit exceptional activity and sintering resistance in propane dehydrogenation(PDH).However,their preparation generally relies on the ligand-protected hydrothermal synthesis method,which suffers from high cost,organic pollution,and low metal utilization,thereby limiting their large-scale preparation and application.Here,we developed a post-treatment strategy based on metal replacement reaction to form subnanometer PtCu alloy in Cu-exchanged zeolite.Copper cations(Cu^(2+) )were first introduced into ZSM-5(MFI)via ion exchange,followed by reduction to form Cu^(0)/Cu^(+) nanoparticles(CuO_(x))inside the zeolite.Subsequently,Pt^(2+) ions were incorporated to form PtCu alloy supported on CuO_(x) nanoparticles via a metal replacement reaction.The as-prepared PtCu5@MFI-K(Pt/Cu=1/5)achieved 49.7%propane conversion with>90%propylene selectivity alongside excellent regeneration stability.The forward rate constant(k_(f))of PtCu5@MFI-K at 550℃ reached 868 molC3H6 gPt^(−1) h^(−1) bar^(−1),which was higher than that of previously reported zeolite-encapsulated Pt-based catalysts.Significantly,Pt and Cu species could dynamically recombine to form PtCu alloy during the regeneration process,showing excellent sinterresistant ability of PtCu5@MFI-K.This work presents a facile,simple,and cost-effective strategy for preparing alloy@zeolite catalysts with tailored metal compositions for important catalytic reactions.
基金the National Natural Science Foundation of China(grant no.22301057)the financial support by the Natural Science Foundation of Hebei Province(grant no.B2023201065)+4 种基金Hebei University High-level Talent Research Program(grant no.521100223025)Y.L.thanks the funding from the National Natural Science Foundation of China(grant no.22305060)Hebei University High-level Talent Research Program(grant no.521100222060)P.Z.acknowledges the financial support from an Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery GrantA.G.W.thanks financial support from an NSERC Canada Graduate Scholarships-Doctoral Program(CGS-D)scholarship.
文摘Metal-containing crystalline porous materials(CPMs)are gaining popularity in heterogeneous catalysis because of their highly crystalline and porous systems,and their excellent chemical tunability.Modification of the metal species and framework structure permits them to have greater activity,selectivity,and stability over other materials.An in-depth understanding of the complex nature of metal active sites in CPMs is essential for revealing the structure-performance relationships and directing the rational design of such catalysts.Compared to conventional characterization techniques,the rapid development of X-ray absorption spectroscopy(XAS)has provided element-and site-specific deep insights into the electronic and structural information of metal species in CPMs.As such,this review begins by summarizing novel XAS techniques and analysis methods in accurately obtaining such data.Next,the combination of XAS with other high-level characterization methods into disclosing the configuration of active sites in metalcontaining CPMs is presented.Then,the utilization of theory-assisted XAS data analysis in examining complex metal-containing CPM catalysts is discussed.Afterwards,advanced in-situ/operando XAS studies into revealing the working sites in metal-containing CPMs under catalytic conditions are highlighted.We conclude by outlining the future challenges and prospects of XAS measurements,data analyses,and in-situ/operando setups in advancing the study of metal-in-CPM catalysts.
