Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.Howev...Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.However,elucidating the transient molecular intermediates remains a critical mechanistic frontier.This study investigates the atomic-scale nucleation process of single-walled carbon nanotubes(SWCNTs)from acetylene on iron(Fe)clusters,utilizing GFN(-x)TB-based nanoreactor molecular dynamics simulations.The simulations reveal a consistent nucleation pathway,regardless of iron cluster size(Fe_(13),Fe_(38),Fe_(55)),where the chemisorption and dissociation of acetylene molecules on the Fe clusters lead to the formation of C_(2)H and C_(2)intermediates.These species then undergo oligomerization,initiating the growth of carbon chains.As the chains cross-link and cyclize,five-membered carbon rings are preferentially formed,which eventually evolve into six-membered rings and more complex sp2-hybridized carbon networks,resembling the cap structures of nascent SWCNTs.Although the nucleation mechanism remains similar across all cluster sizes,larger clusters show enhanced catalytic activity,leading to higher molecular weight hydrocarbons and more extensive carbocyclic networks due to their higher density of active sites per reacting molecule.Crucially,the study highlights the role of C_(2)H as the key active species in the carbon network formation process.These findings offer critical insights into the initial stages of SWCNT nucleation,contributing to a deeper understanding of the mechanisms driving SWCNT growth and guiding the development of optimized synthetic strategies.展开更多
Upgrading carbon dioxide(CO_(2))into value-added bulk chemicals offers a dual-benefit strategy for the carbon neutrality and circular carbon economy.Herein,we develop an integrated CO_(2) valorization strategy that sy...Upgrading carbon dioxide(CO_(2))into value-added bulk chemicals offers a dual-benefit strategy for the carbon neutrality and circular carbon economy.Herein,we develop an integrated CO_(2) valorization strategy that synergizes CO_(2)-H_(2)O co-electrolysis(producing CO/O_(2) feeds)with oxidative double carbonylation of ethylene/acetylene to synthesize CO_(2)-derived C_(4) diesters(dimethyl succinate,fumarate,and maleate).A group of versatile building blocks for manufacturing plasticizers,biodegradable polymers,and pharmaceutical intermediates.Remarkably,CO_(2) exhibits dual functionality:serving simultaneously as a CO/O_(2) source and an explosion suppressant during the oxidative carbonylation process.We systematically investigated the explosion-suppressing efficacy of CO_(2) in flammable gas mixtures(CO/O_(2),C_(2)H_(4)/CO/O_(2),and C_(2)H_(2)/CO/O_(2))across varying concentrations.Notably,the mixed gas stream from CO_(2)/H_(2)O co-electrolysis at an industrial-scale current densities of 400 mA/cm^(2),enabling direct utilization in oxidative double carbonylation reactions with exceptional compatibility and inherent safety.Extended applications were demonstrated through substrate scope expansion and gram-scale synthesis.This study establishes not only a safe protocol for oxidative carbonylation processes,but also opens an innovative pathway for sustainable CO_(2) valorization,including CO surrogate and explosion suppressant.展开更多
Carbon-supported mercury catalysts are extensivelyemployed in calcium carbide-based polyvinyl chloride(PVC)industries,but the usage of mercury-based catalysts can pose an environmental threat due to the release of mer...Carbon-supported mercury catalysts are extensivelyemployed in calcium carbide-based polyvinyl chloride(PVC)industries,but the usage of mercury-based catalysts can pose an environmental threat due to the release of mercury into the surrounding area during the operation period.In this study,a highly active and stable mercury-based catalyst was developed,utilizing the nitrogen atom of the support as the anchor site to enhance the interaction between active sites(HgCl_(2))and the carbon support(N-AC).Thermal loss rate testing and thermogravimetric analysis results demonstrate that,compared to commercial activated carbon,N-doped carbon can effectively increase the heat stability of HgCl_(2).The obtained mercury-based catalysts(HgCl_(2)/N-AC)exhibit significant catalytic performance,achieving 2.5 times the C2H2 conversion of conventional HgCl_(2)/AC catalysts.Experimental analysis combined with theoretical calculations reveals that,contrary to the Eley-Rideal(ER)mechanism of HgCl_(2)/AC,the HgCl_(2)/N-AC catalyst follows the Langmuir-Hinshelwood(LH)adsorption mechanism.The nitrogen sites and HgCl_(2) on the catalyst enhance the adsorption capabilities of the HCl and C2H2,thereby improving the catalytic performance.Based on the modification of the active center by these solid ligands,the loading amount of HgCl_(2) on the catalyst can be further reduced from the current 6.5%to 3%.Considering the absence of successful industrial applications for mercury-free catalysts,and based on the current annual consumption of commercial mercury chloride catalysts in the PVC industry,the widespread adoption of this technology could annually reduce the usage of chlorine mercury by 500 tons,making a notable contribution to mercury compliance,reduction,and emissions control in China.It also serves as a bridge between mercury-free and low-mercury catalysts.Moreover,this solid ligand technology can assist in the application research of mercury-free catalysts.展开更多
Metal-free carbon catalysts have garnered significant attention since their inception.Despite substantial advancements,including widely adopted strategies such as heteroatom doping and defect engineering,their catalyt...Metal-free carbon catalysts have garnered significant attention since their inception.Despite substantial advancements,including widely adopted strategies such as heteroatom doping and defect engineering,their catalytic performance remains inferior to that of metal-based catalysts.In this study,we have predicted and demonstrated that the curvature of carbon plays a pivotal role in the adsorption of acetylene and the overall catalytic performance.First-principles calculations suggest that a tip-enhanced local electric field at the defect site on the curved carbon catalyst enhances the reaction kinetics for acetylene hydrochlorination.The experimental results highlight the structural advantages of the curved defect site,revealing that high-curvature defective carbon(HCDC)demonstrates an adsorption capacity for acetylene that is almost two orders of magnitude higher than that of defective carbon.Notably,HCDC achieves an acetylene conversion of up to 90%at 220℃under a gas hourly space velocity of 300 h^(-1),significantly surpassing the performance of the benchmark 0.25%Au/AC catalyst.This proof-of-concept study reveals the fundamental mechanisms driving the superior performance of carbon catalysts with curved nanostructures and presents a straightforward,environmentally friendly method for large-scale production of carbon materials with precisely controlled nanostructures.It highlights the potential for commercializing metal-free carbon catalysts in acetylene hydrochlorination and related heterogenous catalytic reactions.展开更多
The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally...The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally hazardous mercury-based systems for the coal-based PVC industry.Within a decade of development,the catalytic performance of carbon catalysts has been improved greatly and even shows superiorities over metal catalysts in some cases,which have demonstrated great potential as sustainable alternatives to mercury catalysts.This review provides a comprehensive summary of the recent advancements in carbon catalysts for acetylene hydrochlorination.It encompasses a wide range of aspects,including the identification of active sites from heteroatom doping to intrinsic carbon defects,the various synthetic strategies employed,the reaction and deactivation mechanisms of carbon catalysts,and the current insights into the key challenges that are encountered on the journey from laboratory research to scalable commercialization within the field of carbon catalysts.The review offers foundational insights and practical guidelines for designing green carbon catalysts systems,not only for acetylene hydrochlorination but also for other heterogeneous catalytic reactions.展开更多
Polyvinyl chloride is the most widely used general-purpose plastic and plays a vital role in various industries.Mercury-based catalysts severely limit the green sustainability of industry.Non-metallic carbon materials...Polyvinyl chloride is the most widely used general-purpose plastic and plays a vital role in various industries.Mercury-based catalysts severely limit the green sustainability of industry.Non-metallic carbon materials are very promising alternatives in acetylene hydrochlorination,but their stability remains a challenge of major concern at present.Based on the principle of green chemistry,structurally tunable and defect-rich carbon materials were synthesized by hydrothermal carbonization and pyrolysis using glucose as carbon source and m-phenylenediamine as nitrogen source and cross-linking agent.Experimental characterization and density functional theory confirmed that pyridinic N was the main active site.The introduction of N not only regulated the formation of the hierarchically porous structure of the carbon material,but also increased the adsorption of HCl and decreased the adsorption strength of C_(2)H_(2).The synergistic effect of high N content and porous structure significantly enhanced the catalytic performance of the catalysts in acetylene hydrochlorination.The C_(2)H_(2)conversion was maintained at around98%after 100 h under the reaction conditions(T=220°C,GHSV(C_(2)H_(2))=30 h^(-1),V_(HCl)/VC_(2)H_(2)=1.15).Thus,the one-pot synthesis process used here is a good benchmark for future catalyst research.展开更多
Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide(WS_(2))is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene(...Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide(WS_(2))is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene(AHE),yet remains a major challenge.Herein,we report that by substituting a W atom of WS_(2) with a series of transition metal atoms,sulfur vacancy-confined Cu in the WS_(2) basal plane(Cu@WS_(2)-Sv)is theoretically screened as a superior non-noble metal-based catalyst with higher activity,selectivity,and stability for the AHE than other candidates.The co-adsorption of C_(2)H_(2) and H_(2) and hydrogenation of C_(2)H_(3)^(*) to C_(2)H_(4)^(*) are revealed as the key steps establishing a volcano-like activity trend among the candidates,which present Cu@WS_(2)-Sv as the optimum catalyst combined with molecular dynamics and reaction kinetics analyses.The kinetically more favorable desorption of C_(2)H_(4) than the over hydrogenation path validates a higher selectivity toward C_(2)H_(4) over C_(2)H_(6).Furthermore,a machine-learning model reveals the significant effect of d-electron number and electronegativity of the metal heteroatoms in modulating the AHE activity.展开更多
A comprehensive understanding of the structure and dynamic evolution of catalytic active sites is vital for advancing the study of liquid-phase acetylene hydrochlorination.Here,we successfully developed a Ru-DIPEA/TMS...A comprehensive understanding of the structure and dynamic evolution of catalytic active sites is vital for advancing the study of liquid-phase acetylene hydrochlorination.Here,we successfully developed a Ru-DIPEA/TMS catalyst optimised through systematic composition and condition tuning,demonstrating exceptional performance with 95.5%C_(2)H_(2)conversion and sustaining over 91.1%activity along with nearly 100%selectivity for VCM during a continuous 900-h test.Using a combination of characterisation techniques,including UV–vis spectroscopy,FT-IR spectroscopy,X-ray photoelectron spectroscopy,singlecrystal X-ray diffraction,and X-ray absorption spectroscopy,along with density functional theory(DFT)calculations,the structure and dynamic behaviour of the active sites were thoroughly investigated under the synergistic influence of ligands and HCl.The results revealed that HCl activation induces a significant structural transformation of the active sites,leading to the formation of a hexacoordinate complex,Ru(CO)_(2)C_(12)(C_(6)H_(15)N·HCl)_(2).DFT calculations further elucidated the mechanism underlying active site formation,revealing that an increased electron density around the Ru centre and corresponding changes in its coordination environment play critical roles in enhancing catalyst stability and activity.This study contributes to a deeper understanding of the structural basis of active site evolution during acetylene hydrochlorination,offering both practical insights into industrial applications and foundational knowledge for advancing liquid-phase catalysis.展开更多
In view of the dearth of active components and the unsatisfactory dispersion of Cu-based catalysts,it is imperative to undertake a detailed investigation of catalysts with enhanced catalytic performance.In order to ac...In view of the dearth of active components and the unsatisfactory dispersion of Cu-based catalysts,it is imperative to undertake a detailed investigation of catalysts with enhanced catalytic performance.In order to achieve a balance between the catalytic activity and stability in the reaction process,a series of P-atom doped Cu^(0)/Cu^(δ+)binary Cu-based catalysts were prepared by means of heteroatom introduction and heat treatment.The introduction of P enhanced the stability of Cu during heat treatment,thereby inhibiting the excessive agglomeration of Cu.The structure of the Cu^(0)/Cu^(δ+)binary catalyst was modified through heat treatment and HCl activation,and the relationship between its structure and catalytic activity was subsequently investigated.The activation process of HCl facilitated the conversion of the Cu^(0)state to the Cu-Cl state and augmented the valence state of Cu.The valence modulation of the Cu site by HCl during the reaction prevented the over-reduction of the Cu site by acetylene and enhanced the stability of the catalyst.The 3Cu/5Cu P/AC-800 catalyst was operated for 50 h without significant deactivation under the reaction conditions of T=180°C,V(HCl)/V(C_(2)H_(2))=1.15 and GHSV(C_(2)H_(2))=180 h^(-1).This design strategy provides a novel reference point for further studies of Cu Cl_(2)based catalysts for acetylene hydrochlorination.展开更多
Introducing ligand into the surface of gold(Au)-based catalyst has been recognized as an efficient strategy to enhance the performance of catalyst in acetylene hydrochlorination reaction.However,due to the multifactor...Introducing ligand into the surface of gold(Au)-based catalyst has been recognized as an efficient strategy to enhance the performance of catalyst in acetylene hydrochlorination reaction.However,due to the multifactorial deactivation,the usage of single type of ligand has limitations on the performance improvement.In this work,two types of ligands including a molecular 2-methylimidazole and an ionic cetrimonium are selected to protect Au^(n+)species.After kinetics analysis,advanced characterization,and density functional theory simulation,we demonstrate the optimal interaction model between two ligands and Au species:Two 2-methylimidazole molecules are coordinated with high-valent Au species while cetrimonium is interacted via electrostatic interaction.Except the synergistic effect in the decrease of Au species reduction and agglomeration,the existence of molecular ligand greatly increases the adsorption of hydrogen chloride while the ionic ligand significantly inhibits the deposition of coke.Due to the positive effect of dual-ligands,we achieved 97.1%of acetylene conversion and 0.29 h^(−1) of deactivation rate under high gas hourly space velocity of acetylene.This work establishes a foundation to explore the property-activity relationships in Au-based catalyst via ligand engineering.展开更多
The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective trans...The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective transformations. In this work, a Pd1/ZnO catalyst with single‐atom dispersion of Pd active sites was achieved by decreasing the Pd loading and reducing the sample at a relatively low temperature. The Pd1/ZnO SAC exhibited excellent catalytic performance in the chemoselective hydrogenation of acetylene with comparable chemoselectivity to that of PdZn intermetallic catalysts and a greatly enhanced utilization of Pd metal. Such unusual behaviors of the Pd1/ZnO SAC in acetylene semi‐hydrogenation were ascribed to the high‐valent single Pd active sites, which could promote electrostatic interactions with acetylene but restrain undesired ethylene hydrogenation via the spatial restrictions of σ‐chemical bonding toward ethylene.展开更多
Nitrogen‐doped ordered mesoporous carbon （N‐OMC） catalysts were directly synthesized using SBA‐15 as a hard template and sucrose as a carbon source. Urea, which was used as the nitrogen source, was carbonized wit...Nitrogen‐doped ordered mesoporous carbon （N‐OMC） catalysts were directly synthesized using SBA‐15 as a hard template and sucrose as a carbon source. Urea, which was used as the nitrogen source, was carbonized with sucrose. A 3.6 wt% nitrogen doping of the carbon framework was achieved, with more than 70%of the nitrogen incorporated as quaternary nitrogen species. Only 0.2 wt% nitrogen doping, with only 32.7% quaternary nitrogen incorporation was obtained in an N‐OMC catalyst （N‐OMC‐T） prepared using a two‐step post‐synthesis method. The acetylene hy‐drochlorination activities of N‐OMC catalysts prepared via the one‐step method were higher than that of the N‐OMC‐T catalyst because of the higher nitrogen loadings.展开更多
A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts c...A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts calcined at different temperatures were characterized using NH3-TPD, pyridine-FTIR, X-ray diffraction, and Raman techniques. It was found that the calcination process could not only change the structure of these catalysts but also modify the amount of surface acidity on the catalysts. The catalyst calcined at 400 ℃ exhibited the highest conversion of acetylene （94.6%） and highest selectivity to vinyl fluoride （83.4%） and lower coke deposition selectivity （0.72%）. The highest activity was related to the largest amount of surface acidity on the catalyst, and the coke deposition was also related to the total amount of surface acidic sites.展开更多
A clay-like conductive material comprising polyaniline（PANI）-acetylene black particles is fabricated as a hole conductor for dye sensitized solar cell（DSSC）.The results show that the introduction of acetylene blac...A clay-like conductive material comprising polyaniline（PANI）-acetylene black particles is fabricated as a hole conductor for dye sensitized solar cell（DSSC）.The results show that the introduction of acetylene black into the polymer electrolyte improves the photovoltaic behavior of solid-state DSSC,owing to the increase of the hole mobility of PANI electrolyte,the improvement of the wetting quality of the composite electrolyte,and the reinforcement of interface contact between electrode and the electrolyte.Finally,the overall energy conversion efficiency of DSSC with PANI-50%（in weight）acetylene black electrolyte is 48% of that of liquid DSSC.Therefore,the PANI-acetylene black composition is a credible alternative to hole conductor in application of solid DSSC.展开更多
Pd/C catalysts were prepared by deposited Pd nanoparticles （NPs） on different carbon supports including activated carbon （AC）, graphite oxide （GO）, and reduced graphite oxide （rGO） using sol-immobilization met...Pd/C catalysts were prepared by deposited Pd nanoparticles （NPs） on different carbon supports including activated carbon （AC）, graphite oxide （GO）, and reduced graphite oxide （rGO） using sol-immobilization method. Through transmission electron microscopy, powder X-ray di raction, and X-ray photoelectron spectroscopy, the role of the carbon supports for the catalytic performances of Pd/C catalysts was examined in selective hydrogenation of acetylene. The results indicate that Pd/AC exhibited higher activity and selectivity than Pd/GO and Pd/rGO in the gas phase selective hydrogenation of acetylene. Thermal and chemical treatment of AC supports also have some effect on the catalytic performance of Pd/AC catalysts. The differences in the activity and selectivity of various Pd/C catalysts were partly attributed to the metal-support interaction.展开更多
The effect of solvation on the conformation of acetylene has been studied by adding one water molecule at a time. Quantum chemical calculations of the n＋ （C2H2）（H2O）n （n=1-5） clusters indicate that the H2O mole...The effect of solvation on the conformation of acetylene has been studied by adding one water molecule at a time. Quantum chemical calculations of the n＋ （C2H2）（H2O）n （n=1-5） clusters indicate that the H2O molecules prefer to form the OH...Tr interaction rather than the CH...O interaction. This solvation motif is different from that of neutral （C2H2）（H2O）n （n=1-4） clusters, in which the H2O molecules prefer to form the CH...O and OH...C Hbonds. For the H＋（C2H2）（H2O）n cationic clusters, the first solvation shell consists of one ring structure with two OH...Tr H-bonds and three water molecules, which is completed at n=4. Simulated infrared spectra reveal that vibrational frequencies of OH... H-bonded O-H stretching afford a sensitive probe for exploring the solvation of acetylene by protonated water molecules. Infrared spectra of the H＋ （C2H2）（H2O）n （n=1-5） clusters could be readily measured by the infrared photodissociation technique and thus provide useful information for the understanding of solvation processes.展开更多
Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vi...Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vital to explore alternative catalysts without mercury. We report here that N-doped carbon can catalyze directly transformation of acetylene to vinyl chloride. Particularly, N-doped high surface area mesoporous carbon exhibits a rather high activity with the acetylene conversion reaching 77% and vinyl chloride selectivity above 98% at a space velocity of 1.0 mL.min-l.g-1 and 200 ~C. It delivers a stable performa℃nce within a test period of 100h and no obvious deactivation is observed, demonstrating potentials to substitute the notoriously toxic mercuric chloride catalyst.展开更多
Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10～2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ...Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10～2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ethylene than Ni/Si O_2.This is attributed to the formation Ni-Ga alloy and Ni3 Ga intermetallic compound(IMC) where there was a charge transfer from Ga to Ni,which is favorable for reducing the adsorption strength and amount of ethylene on Ni atoms.As a result,the over-hydrogenation,the C–C bond hydrogenolysis and the polymerization were suppressed,and subsequently the selectivity to ethylene was enhanced.With the decrease of Ni/Ga atomic ratio,the activity and stability of the Ni_xGa/SiO_2 catalysts increased first and then decreased,while the ethylene selectivity tended to increase.Ni_5 Ga/SiO_2 exhibited the best performance.Under the conditions of 180 °C,0.1 MPa,and a reactant(1.0 vol% acetylene,5.0 vol% H_2 and 94 vol% N_2) with the space velocity of 36,000 m L h^(-1) g^(-1),the acetylene conversion maintained at 100% on Ni_5 Ga/SiO_2 during 120 h time on stream and the selectivity to ethylene was 75%～81%after reaction for 68 h.It was also found that the formation of Ni-Ga alloy and Ni_3 Ga IMC suppressed the incorporation of carbon to form NiCx,subsequently enhancing the catalyst stability.Additionally,with increasing the Ga content,the catalyst acid amount and strength tended to increase,which promoted the polymerization and carbon deposition and so the catalyst deactivation.展开更多
The IB metal(Au,Ag and Cu)alloyed Pd single atom catalysts had been proved to be efficient in promoting the selectivity for hydrogenation of acetylene to ethylene.As a base metal in the same group as Pd,the Ni-based c...The IB metal(Au,Ag and Cu)alloyed Pd single atom catalysts had been proved to be efficient in promoting the selectivity for hydrogenation of acetylene to ethylene.As a base metal in the same group as Pd,the Ni-based catalysts are also active for hydrogenation reactions.Herein,the effects of the IB metals on the Ni/SiO2 catalyst for the selective hydrogenation of acetylene were systematically studied.Different from the Pd/SiO2 catalyst,the monometallic Ni/SiO2 catalyst is not active at low temperatures.The addition of the IB metals to the Ni/SiO2 catalysts can greatly enhance the activity.Besides,the catalytic activity of the AuNix/SiO2 and CuNix/SiO2 catalysts increase with the reduction temperature,while the AgNix/SiO2 catalysts are not sensitive to the pretreatment temperature.The origin of the effect of the different IB metals on the Ni-based catalysts for selective hydrogenation of acetylene is discussed based on the characterizations by XRD,TPR and microcalorimetric measurements.展开更多
基金supported by the National Key R&D Program of China(2022YFA1604100)the National Natural Science Foundation of China(22302220,22372187,1972157,21972160,22402218)+2 种基金the National Science Fund for Distinguished Young Scholars of China(22225206)the Fundamental Research Program of Shanxi Province(202203021222403)the Youth Innovation Promotion Association CAS(2020179)。
文摘Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.However,elucidating the transient molecular intermediates remains a critical mechanistic frontier.This study investigates the atomic-scale nucleation process of single-walled carbon nanotubes(SWCNTs)from acetylene on iron(Fe)clusters,utilizing GFN(-x)TB-based nanoreactor molecular dynamics simulations.The simulations reveal a consistent nucleation pathway,regardless of iron cluster size(Fe_(13),Fe_(38),Fe_(55)),where the chemisorption and dissociation of acetylene molecules on the Fe clusters lead to the formation of C_(2)H and C_(2)intermediates.These species then undergo oligomerization,initiating the growth of carbon chains.As the chains cross-link and cyclize,five-membered carbon rings are preferentially formed,which eventually evolve into six-membered rings and more complex sp2-hybridized carbon networks,resembling the cap structures of nascent SWCNTs.Although the nucleation mechanism remains similar across all cluster sizes,larger clusters show enhanced catalytic activity,leading to higher molecular weight hydrocarbons and more extensive carbocyclic networks due to their higher density of active sites per reacting molecule.Crucially,the study highlights the role of C_(2)H as the key active species in the carbon network formation process.These findings offer critical insights into the initial stages of SWCNT nucleation,contributing to a deeper understanding of the mechanisms driving SWCNT growth and guiding the development of optimized synthetic strategies.
文摘Upgrading carbon dioxide(CO_(2))into value-added bulk chemicals offers a dual-benefit strategy for the carbon neutrality and circular carbon economy.Herein,we develop an integrated CO_(2) valorization strategy that synergizes CO_(2)-H_(2)O co-electrolysis(producing CO/O_(2) feeds)with oxidative double carbonylation of ethylene/acetylene to synthesize CO_(2)-derived C_(4) diesters(dimethyl succinate,fumarate,and maleate).A group of versatile building blocks for manufacturing plasticizers,biodegradable polymers,and pharmaceutical intermediates.Remarkably,CO_(2) exhibits dual functionality:serving simultaneously as a CO/O_(2) source and an explosion suppressant during the oxidative carbonylation process.We systematically investigated the explosion-suppressing efficacy of CO_(2) in flammable gas mixtures(CO/O_(2),C_(2)H_(4)/CO/O_(2),and C_(2)H_(2)/CO/O_(2))across varying concentrations.Notably,the mixed gas stream from CO_(2)/H_(2)O co-electrolysis at an industrial-scale current densities of 400 mA/cm^(2),enabling direct utilization in oxidative double carbonylation reactions with exceptional compatibility and inherent safety.Extended applications were demonstrated through substrate scope expansion and gram-scale synthesis.This study establishes not only a safe protocol for oxidative carbonylation processes,but also opens an innovative pathway for sustainable CO_(2) valorization,including CO surrogate and explosion suppressant.
基金supported by the National Key Research and Development Program of China(2024YFC3907904).
文摘Carbon-supported mercury catalysts are extensivelyemployed in calcium carbide-based polyvinyl chloride(PVC)industries,but the usage of mercury-based catalysts can pose an environmental threat due to the release of mercury into the surrounding area during the operation period.In this study,a highly active and stable mercury-based catalyst was developed,utilizing the nitrogen atom of the support as the anchor site to enhance the interaction between active sites(HgCl_(2))and the carbon support(N-AC).Thermal loss rate testing and thermogravimetric analysis results demonstrate that,compared to commercial activated carbon,N-doped carbon can effectively increase the heat stability of HgCl_(2).The obtained mercury-based catalysts(HgCl_(2)/N-AC)exhibit significant catalytic performance,achieving 2.5 times the C2H2 conversion of conventional HgCl_(2)/AC catalysts.Experimental analysis combined with theoretical calculations reveals that,contrary to the Eley-Rideal(ER)mechanism of HgCl_(2)/AC,the HgCl_(2)/N-AC catalyst follows the Langmuir-Hinshelwood(LH)adsorption mechanism.The nitrogen sites and HgCl_(2) on the catalyst enhance the adsorption capabilities of the HCl and C2H2,thereby improving the catalytic performance.Based on the modification of the active center by these solid ligands,the loading amount of HgCl_(2) on the catalyst can be further reduced from the current 6.5%to 3%.Considering the absence of successful industrial applications for mercury-free catalysts,and based on the current annual consumption of commercial mercury chloride catalysts in the PVC industry,the widespread adoption of this technology could annually reduce the usage of chlorine mercury by 500 tons,making a notable contribution to mercury compliance,reduction,and emissions control in China.It also serves as a bridge between mercury-free and low-mercury catalysts.Moreover,this solid ligand technology can assist in the application research of mercury-free catalysts.
文摘Metal-free carbon catalysts have garnered significant attention since their inception.Despite substantial advancements,including widely adopted strategies such as heteroatom doping and defect engineering,their catalytic performance remains inferior to that of metal-based catalysts.In this study,we have predicted and demonstrated that the curvature of carbon plays a pivotal role in the adsorption of acetylene and the overall catalytic performance.First-principles calculations suggest that a tip-enhanced local electric field at the defect site on the curved carbon catalyst enhances the reaction kinetics for acetylene hydrochlorination.The experimental results highlight the structural advantages of the curved defect site,revealing that high-curvature defective carbon(HCDC)demonstrates an adsorption capacity for acetylene that is almost two orders of magnitude higher than that of defective carbon.Notably,HCDC achieves an acetylene conversion of up to 90%at 220℃under a gas hourly space velocity of 300 h^(-1),significantly surpassing the performance of the benchmark 0.25%Au/AC catalyst.This proof-of-concept study reveals the fundamental mechanisms driving the superior performance of carbon catalysts with curved nanostructures and presents a straightforward,environmentally friendly method for large-scale production of carbon materials with precisely controlled nanostructures.It highlights the potential for commercializing metal-free carbon catalysts in acetylene hydrochlorination and related heterogenous catalytic reactions.
文摘The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally hazardous mercury-based systems for the coal-based PVC industry.Within a decade of development,the catalytic performance of carbon catalysts has been improved greatly and even shows superiorities over metal catalysts in some cases,which have demonstrated great potential as sustainable alternatives to mercury catalysts.This review provides a comprehensive summary of the recent advancements in carbon catalysts for acetylene hydrochlorination.It encompasses a wide range of aspects,including the identification of active sites from heteroatom doping to intrinsic carbon defects,the various synthetic strategies employed,the reaction and deactivation mechanisms of carbon catalysts,and the current insights into the key challenges that are encountered on the journey from laboratory research to scalable commercialization within the field of carbon catalysts.The review offers foundational insights and practical guidelines for designing green carbon catalysts systems,not only for acetylene hydrochlorination but also for other heterogeneous catalytic reactions.
基金supported by the Tianchi Innovation Leading Talent Development Fund(No.CZ002710)in Xinjiangthe Taishan Scholars Program of Shandong Province(No.tsqn202103051)+4 种基金the Project of Science and Technology Development of Yantai City(No.2023JCYJ073)Natural science foundation of Shandong province(No.ZR2023MB064)special funds for over provincial level leading talent of Yantai citythe Start-Up Foundation for High-level Professionals of Shihezi University(No.RCZK201932)Tianshan Talents Training Program of Xinjiang(Science and Technology Innovation Team,No.2022TSYCTD0021)。
文摘Polyvinyl chloride is the most widely used general-purpose plastic and plays a vital role in various industries.Mercury-based catalysts severely limit the green sustainability of industry.Non-metallic carbon materials are very promising alternatives in acetylene hydrochlorination,but their stability remains a challenge of major concern at present.Based on the principle of green chemistry,structurally tunable and defect-rich carbon materials were synthesized by hydrothermal carbonization and pyrolysis using glucose as carbon source and m-phenylenediamine as nitrogen source and cross-linking agent.Experimental characterization and density functional theory confirmed that pyridinic N was the main active site.The introduction of N not only regulated the formation of the hierarchically porous structure of the carbon material,but also increased the adsorption of HCl and decreased the adsorption strength of C_(2)H_(2).The synergistic effect of high N content and porous structure significantly enhanced the catalytic performance of the catalysts in acetylene hydrochlorination.The C_(2)H_(2)conversion was maintained at around98%after 100 h under the reaction conditions(T=220°C,GHSV(C_(2)H_(2))=30 h^(-1),V_(HCl)/VC_(2)H_(2)=1.15).Thus,the one-pot synthesis process used here is a good benchmark for future catalyst research.
文摘Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide(WS_(2))is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene(AHE),yet remains a major challenge.Herein,we report that by substituting a W atom of WS_(2) with a series of transition metal atoms,sulfur vacancy-confined Cu in the WS_(2) basal plane(Cu@WS_(2)-Sv)is theoretically screened as a superior non-noble metal-based catalyst with higher activity,selectivity,and stability for the AHE than other candidates.The co-adsorption of C_(2)H_(2) and H_(2) and hydrogenation of C_(2)H_(3)^(*) to C_(2)H_(4)^(*) are revealed as the key steps establishing a volcano-like activity trend among the candidates,which present Cu@WS_(2)-Sv as the optimum catalyst combined with molecular dynamics and reaction kinetics analyses.The kinetically more favorable desorption of C_(2)H_(4) than the over hydrogenation path validates a higher selectivity toward C_(2)H_(4) over C_(2)H_(6).Furthermore,a machine-learning model reveals the significant effect of d-electron number and electronegativity of the metal heteroatoms in modulating the AHE activity.
基金supported by the National Natural Science Foundation of China(No.22378308)Jing-Jin-Ji Regional Integrated Environmental Improvement-National Science and Technology Major Project(No.2024ZD1200301–2)the Scientific and Technological Project of Yunnan Precious Metal Laboratory(No.YPML2023050202)。
文摘A comprehensive understanding of the structure and dynamic evolution of catalytic active sites is vital for advancing the study of liquid-phase acetylene hydrochlorination.Here,we successfully developed a Ru-DIPEA/TMS catalyst optimised through systematic composition and condition tuning,demonstrating exceptional performance with 95.5%C_(2)H_(2)conversion and sustaining over 91.1%activity along with nearly 100%selectivity for VCM during a continuous 900-h test.Using a combination of characterisation techniques,including UV–vis spectroscopy,FT-IR spectroscopy,X-ray photoelectron spectroscopy,singlecrystal X-ray diffraction,and X-ray absorption spectroscopy,along with density functional theory(DFT)calculations,the structure and dynamic behaviour of the active sites were thoroughly investigated under the synergistic influence of ligands and HCl.The results revealed that HCl activation induces a significant structural transformation of the active sites,leading to the formation of a hexacoordinate complex,Ru(CO)_(2)C_(12)(C_(6)H_(15)N·HCl)_(2).DFT calculations further elucidated the mechanism underlying active site formation,revealing that an increased electron density around the Ru centre and corresponding changes in its coordination environment play critical roles in enhancing catalyst stability and activity.This study contributes to a deeper understanding of the structural basis of active site evolution during acetylene hydrochlorination,offering both practical insights into industrial applications and foundational knowledge for advancing liquid-phase catalysis.
基金supported by the National Natural Science Foundation of China(No.22062021)the Science and Technology Project of Xinjiang supported by Central Government(No.2022BC001)+3 种基金Science and Technology Planning Project(No.2024AB048)Tianshan Talents Training Program of Xinjiang(Science and Technology Innovation Team,No.CZ002701)the Start-Up Foundation for high-level professionals of Shihezi University(No.RCZK201932)2024 Talent Development Fund-Tianchi Young Doctor of Excellence(No.CZ002744)。
文摘In view of the dearth of active components and the unsatisfactory dispersion of Cu-based catalysts,it is imperative to undertake a detailed investigation of catalysts with enhanced catalytic performance.In order to achieve a balance between the catalytic activity and stability in the reaction process,a series of P-atom doped Cu^(0)/Cu^(δ+)binary Cu-based catalysts were prepared by means of heteroatom introduction and heat treatment.The introduction of P enhanced the stability of Cu during heat treatment,thereby inhibiting the excessive agglomeration of Cu.The structure of the Cu^(0)/Cu^(δ+)binary catalyst was modified through heat treatment and HCl activation,and the relationship between its structure and catalytic activity was subsequently investigated.The activation process of HCl facilitated the conversion of the Cu^(0)state to the Cu-Cl state and augmented the valence state of Cu.The valence modulation of the Cu site by HCl during the reaction prevented the over-reduction of the Cu site by acetylene and enhanced the stability of the catalyst.The 3Cu/5Cu P/AC-800 catalyst was operated for 50 h without significant deactivation under the reaction conditions of T=180°C,V(HCl)/V(C_(2)H_(2))=1.15 and GHSV(C_(2)H_(2))=180 h^(-1).This design strategy provides a novel reference point for further studies of Cu Cl_(2)based catalysts for acetylene hydrochlorination.
基金supported by the National Natural Science Foundation of China(No.22068031)Yunnan Precious Metals Laboratory Science and Technology Project(No.YPML-2022050237)+4 种基金Major Science and Technology Project of Yunnan Precious Metal Laboratory(No.YPML-2023050202)the Science and Technology Project of Xinjiang Bingtuan supported by Central Government(No.2022BC001)Tianshan Talents Training Program of Xinjiang Science and Technology Innovation Team(No.2022TSYCTD0021)the Start-Up Foundation for Young Scientists of Shihezi University(No.RCZK202419)the Project of Achievement Transformation and Technology Extension of Shihezi University(No.CGZH202302)。
文摘Introducing ligand into the surface of gold(Au)-based catalyst has been recognized as an efficient strategy to enhance the performance of catalyst in acetylene hydrochlorination reaction.However,due to the multifactorial deactivation,the usage of single type of ligand has limitations on the performance improvement.In this work,two types of ligands including a molecular 2-methylimidazole and an ionic cetrimonium are selected to protect Au^(n+)species.After kinetics analysis,advanced characterization,and density functional theory simulation,we demonstrate the optimal interaction model between two ligands and Au species:Two 2-methylimidazole molecules are coordinated with high-valent Au species while cetrimonium is interacted via electrostatic interaction.Except the synergistic effect in the decrease of Au species reduction and agglomeration,the existence of molecular ligand greatly increases the adsorption of hydrogen chloride while the ionic ligand significantly inhibits the deposition of coke.Due to the positive effect of dual-ligands,we achieved 97.1%of acetylene conversion and 0.29 h^(−1) of deactivation rate under high gas hourly space velocity of acetylene.This work establishes a foundation to explore the property-activity relationships in Au-based catalyst via ligand engineering.
基金supported by the National Natural Science Foundation of China(21573232)~~
文摘The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective transformations. In this work, a Pd1/ZnO catalyst with single‐atom dispersion of Pd active sites was achieved by decreasing the Pd loading and reducing the sample at a relatively low temperature. The Pd1/ZnO SAC exhibited excellent catalytic performance in the chemoselective hydrogenation of acetylene with comparable chemoselectivity to that of PdZn intermetallic catalysts and a greatly enhanced utilization of Pd metal. Such unusual behaviors of the Pd1/ZnO SAC in acetylene semi‐hydrogenation were ascribed to the high‐valent single Pd active sites, which could promote electrostatic interactions with acetylene but restrain undesired ethylene hydrogenation via the spatial restrictions of σ‐chemical bonding toward ethylene.
基金supported by the National Natural Science Foundation of China (20803064)the Natural Science Foundation of Zhejiang Province (Y4090348)~~
文摘Nitrogen‐doped ordered mesoporous carbon （N‐OMC） catalysts were directly synthesized using SBA‐15 as a hard template and sucrose as a carbon source. Urea, which was used as the nitrogen source, was carbonized with sucrose. A 3.6 wt% nitrogen doping of the carbon framework was achieved, with more than 70%of the nitrogen incorporated as quaternary nitrogen species. Only 0.2 wt% nitrogen doping, with only 32.7% quaternary nitrogen incorporation was obtained in an N‐OMC catalyst （N‐OMC‐T） prepared using a two‐step post‐synthesis method. The acetylene hy‐drochlorination activities of N‐OMC catalysts prepared via the one‐step method were higher than that of the N‐OMC‐T catalyst because of the higher nitrogen loadings.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.20873125）,
文摘A La-modified Al2O3 catalyst was prepared with deposition-precipitation method. The effect of calcination temperature on the reactivity for vapor phase hydrofluorination of acetylene to vinyl fluoride. The catalysts calcined at different temperatures were characterized using NH3-TPD, pyridine-FTIR, X-ray diffraction, and Raman techniques. It was found that the calcination process could not only change the structure of these catalysts but also modify the amount of surface acidity on the catalysts. The catalyst calcined at 400 ℃ exhibited the highest conversion of acetylene （94.6%） and highest selectivity to vinyl fluoride （83.4%） and lower coke deposition selectivity （0.72%）. The highest activity was related to the largest amount of surface acidity on the catalyst, and the coke deposition was also related to the total amount of surface acidic sites.
文摘A clay-like conductive material comprising polyaniline（PANI）-acetylene black particles is fabricated as a hole conductor for dye sensitized solar cell（DSSC）.The results show that the introduction of acetylene black into the polymer electrolyte improves the photovoltaic behavior of solid-state DSSC,owing to the increase of the hole mobility of PANI electrolyte,the improvement of the wetting quality of the composite electrolyte,and the reinforcement of interface contact between electrode and the electrolyte.Finally,the overall energy conversion efficiency of DSSC with PANI-50%（in weight）acetylene black electrolyte is 48% of that of liquid DSSC.Therefore,the PANI-acetylene black composition is a credible alternative to hole conductor in application of solid DSSC.
文摘Pd/C catalysts were prepared by deposited Pd nanoparticles （NPs） on different carbon supports including activated carbon （AC）, graphite oxide （GO）, and reduced graphite oxide （rGO） using sol-immobilization method. Through transmission electron microscopy, powder X-ray di raction, and X-ray photoelectron spectroscopy, the role of the carbon supports for the catalytic performances of Pd/C catalysts was examined in selective hydrogenation of acetylene. The results indicate that Pd/AC exhibited higher activity and selectivity than Pd/GO and Pd/rGO in the gas phase selective hydrogenation of acetylene. Thermal and chemical treatment of AC supports also have some effect on the catalytic performance of Pd/AC catalysts. The differences in the activity and selectivity of various Pd/C catalysts were partly attributed to the metal-support interaction.
基金This work was supported by the National Natural Science Foundation of China （No.21273232 and No.21327901） and the Key Research Program of the Chinese Academy of Science （No.KGZD-EW-T05）. Ling Jiang acknowledges Hundred Talents Program of Chinese Academy of Sciences and Collaborative Innovation Center of Chemistry for Energy and Materials.
文摘The effect of solvation on the conformation of acetylene has been studied by adding one water molecule at a time. Quantum chemical calculations of the n＋ （C2H2）（H2O）n （n=1-5） clusters indicate that the H2O molecules prefer to form the OH...Tr interaction rather than the CH...O interaction. This solvation motif is different from that of neutral （C2H2）（H2O）n （n=1-4） clusters, in which the H2O molecules prefer to form the CH...O and OH...C Hbonds. For the H＋（C2H2）（H2O）n cationic clusters, the first solvation shell consists of one ring structure with two OH...Tr H-bonds and three water molecules, which is completed at n=4. Simulated infrared spectra reveal that vibrational frequencies of OH... H-bonded O-H stretching afford a sensitive probe for exploring the solvation of acetylene by protonated water molecules. Infrared spectra of the H＋ （C2H2）（H2O）n （n=1-5） clusters could be readily measured by the infrared photodissociation technique and thus provide useful information for the understanding of solvation processes.
基金supported by the Natural Science Foundation of China(No.11079005 and 21033009)the Ministry of Science and Technology of China(2011CBA00503 and 2012CB720302)
文摘Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vital to explore alternative catalysts without mercury. We report here that N-doped carbon can catalyze directly transformation of acetylene to vinyl chloride. Particularly, N-doped high surface area mesoporous carbon exhibits a rather high activity with the acetylene conversion reaching 77% and vinyl chloride selectivity above 98% at a space velocity of 1.0 mL.min-l.g-1 and 200 ~C. It delivers a stable performa℃nce within a test period of 100h and no obvious deactivation is observed, demonstrating potentials to substitute the notoriously toxic mercuric chloride catalyst.
基金supported by the National Natural Science Foundation of China (21576193)
文摘Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10～2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ethylene than Ni/Si O_2.This is attributed to the formation Ni-Ga alloy and Ni3 Ga intermetallic compound(IMC) where there was a charge transfer from Ga to Ni,which is favorable for reducing the adsorption strength and amount of ethylene on Ni atoms.As a result,the over-hydrogenation,the C–C bond hydrogenolysis and the polymerization were suppressed,and subsequently the selectivity to ethylene was enhanced.With the decrease of Ni/Ga atomic ratio,the activity and stability of the Ni_xGa/SiO_2 catalysts increased first and then decreased,while the ethylene selectivity tended to increase.Ni_5 Ga/SiO_2 exhibited the best performance.Under the conditions of 180 °C,0.1 MPa,and a reactant(1.0 vol% acetylene,5.0 vol% H_2 and 94 vol% N_2) with the space velocity of 36,000 m L h^(-1) g^(-1),the acetylene conversion maintained at 100% on Ni_5 Ga/SiO_2 during 120 h time on stream and the selectivity to ethylene was 75%～81%after reaction for 68 h.It was also found that the formation of Ni-Ga alloy and Ni_3 Ga IMC suppressed the incorporation of carbon to form NiCx,subsequently enhancing the catalyst stability.Additionally,with increasing the Ga content,the catalyst acid amount and strength tended to increase,which promoted the polymerization and carbon deposition and so the catalyst deactivation.
文摘The IB metal(Au,Ag and Cu)alloyed Pd single atom catalysts had been proved to be efficient in promoting the selectivity for hydrogenation of acetylene to ethylene.As a base metal in the same group as Pd,the Ni-based catalysts are also active for hydrogenation reactions.Herein,the effects of the IB metals on the Ni/SiO2 catalyst for the selective hydrogenation of acetylene were systematically studied.Different from the Pd/SiO2 catalyst,the monometallic Ni/SiO2 catalyst is not active at low temperatures.The addition of the IB metals to the Ni/SiO2 catalysts can greatly enhance the activity.Besides,the catalytic activity of the AuNix/SiO2 and CuNix/SiO2 catalysts increase with the reduction temperature,while the AgNix/SiO2 catalysts are not sensitive to the pretreatment temperature.The origin of the effect of the different IB metals on the Ni-based catalysts for selective hydrogenation of acetylene is discussed based on the characterizations by XRD,TPR and microcalorimetric measurements.
