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
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
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
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
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
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
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
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
The development of efficient and stable non-mercury catalysts for the chlor-alkali industry is desirable but remains a great challenge.Herein,we design a series of ruthenium catalysts for acetylene hydrochlorination b...The development of efficient and stable non-mercury catalysts for the chlor-alkali industry is desirable but remains a great challenge.Herein,we design a series of ruthenium catalysts for acetylene hydrochlorination by regulating the electronic structure of ruthenium ions through coordination with various ligands(thiourea,phenanthroline,and L-lactic).The turnover frequencies(TOFs)and apparent activation energies for the acetylene hydrochlorination have a linear relationship with the binding energy of Ru3+in the ruthenium catalysts.The synergetic effect of the ruthenium ion and ligands plays an important role in acetylene hydrochlorination.The Ru-Thi/AC catalyst with thiourea as the ligand shows the highest TOF and stability in acetylene hydrochlorination.The present study provides a rational method to regulate the electronic structure of supported metal catalysts with high catalytic performance exhibited by the carbon-supported heterogeneous catalysts.展开更多
Herein,we report an excellent,supported Ru(III)‐ChCl/AC catalyst with lower Ru content,where the ionic complex ChRuCl4 serves as the active component for acetylene hydrochlorination.The prepared heterogeneous Ru‐10%...Herein,we report an excellent,supported Ru(III)‐ChCl/AC catalyst with lower Ru content,where the ionic complex ChRuCl4 serves as the active component for acetylene hydrochlorination.The prepared heterogeneous Ru‐10%ChCl/AC catalyst shows excellent activity and long‐term stability.In this system,ChCl provides an environment for the ChRuCl4 to be stabilized as Ru(III),thus suppressing the reduction of the active species and the aggregation of ruthenium species during the reaction.The interaction between reactants and catalyst species was investigated by catalyst characterizations in combination with DFT calculations to disclose the effect of the ChRuCl4 complex and ChCl on the catalytic performance.This inexpensive,efficient,and long‐term catalyst is a competitive candidate for application in the hydrochlorination industry.展开更多
The activation of HCl by cationic Au in the presence of C2H2 is important for the construction of active Au sites and in acetylene hydrochlorination.Here,we report a strategy for activating HCl by the Au-based support...The activation of HCl by cationic Au in the presence of C2H2 is important for the construction of active Au sites and in acetylene hydrochlorination.Here,we report a strategy for activating HCl by the Au-based supported ionic liquid phase(Au–SILP)technology with the[N(CN)2^–]anion.This strategy enables HCl to accept electrons from[N(CN)2^–]anions in Au–[N(CN)2^–]complexes rather than from pure[Bmim][N(CN)2],leading to notable improvement in both the reaction path and the stability of the catalyst without changing the reaction triggered by acetylene adsorption.Furthermore,the induction period of the Au–SILP catalyst was shown to be absent in the reaction process due to the high Au(III)content in the Au(Ⅲ)/Au(Ⅰ)site and the high substrate diffusion rate in the ionic liquid layer.This work provides a facile method to improve the stability of Au-based catalysts for acetylene hydrochlorination.展开更多
AuCl3 loaded structured catalysts were prepared on SiC foam supported with pre-coated activated carbon layers. The catalytic properties of the structured catalysts towards hydrochlorination of acetylene were tested in...AuCl3 loaded structured catalysts were prepared on SiC foam supported with pre-coated activated carbon layers. The catalytic properties of the structured catalysts towards hydrochlorination of acetylene were tested in a fixed- bed reactor with the AuCl3 loaded on activated carbon pellets as a reference. For isopyknic catalysts, the structured catalyst with only one fifth of the Au amount as that was used on the reference catalyst exhibited even a little higher acetylene conversion and much better stability than the latter no matter what the gas hourly space velocities of acetylene were used. The results indicated that the more homogeneous distribution of AuCl3 particles and better heat transfer along the fixed-bed reactor originated from the low pressure drop and high thermal conductivity of the SiC foam supported structured catalysts might be able to account for their improved efficiency and stability. It is befieved that these novel structured C/Au catalysts can be potentially applied in VCM industrialization in view of their greatly reduced cost and much prolonged life.展开更多
Activated carbon-supported mercuric chloride（HgCl2） is used as an industrial catalyst for acetylene hydrochlorination. However, the characteristic of easy sublimation of HgCl2 leads to the deactivation o the catalys...Activated carbon-supported mercuric chloride（HgCl2） is used as an industrial catalyst for acetylene hydrochlorination. However, the characteristic of easy sublimation of HgCl2 leads to the deactivation o the catalyst. Here, we showed that the thermal stability of the Hg/AC catalyst can be evidently improved when Cs Cl is added into the Hg/AC catalyst. Compared with the pure Hg/AC catalyst, the sublimation rate of HgCl2 from the Hg–Cs/AC catalyst decreased significantly and the Hg–Cs/AC catalyst showed bette catalytic activity and stability in the reaction. This promoting effect is related to the existence of cesium mercuric chlorides（CsxHgyCl（x＋2y）） highlighted by XRD, HR-TEM and EDX analyses. Thus, reacting HgCl2 with alkali chlorides to form alkali-mercuric chlorides may be a key to design highly efficient and thermally stable mercuric chloride catalyst for hydrochlorination reactions.展开更多
We recently reported an N‐doped mesoporous carbon(N‐MC)extrudate,with major quaternary N species,prepared by a cheap and convenient method through direct carbonization of wheat flour with silica,which has excellent ...We recently reported an N‐doped mesoporous carbon(N‐MC)extrudate,with major quaternary N species,prepared by a cheap and convenient method through direct carbonization of wheat flour with silica,which has excellent catalytic performance in acetylene hydrochlorination.Herein,we examined the activity of Au supported on N‐MC(Au/N‐MC)and compared it with that of Au supported on nitrogen‐free mesoporous carbon(Au/MC).The acetylene conversion of Au/N‐MC was 50%at 180°C with an acetylene space velocity of 600 h–1 and VHCl/VC2H2 of 1.1,which was double the activity of Au/MC(25%).The introduced nitrogen atoms acted as anchor sites that stabilized the Au3+species and inhibited the reduction of Au3+to Au0 during the preparation of Au/N‐MC catalysts.展开更多
Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by con...Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by controlling the impregnation solutions. The π electrons flowing from acetylene to Cu site are facilitated over the electron-deficient Cu sites, achieving high activation of C≡C bond. The contradiction between the increased activation of acetylene required for enhanced catalytic activity and the resistance of Cu site to reduction by acetylene required for maintaining catalytic stability can be balanced by establishing strong interactions of Cu site with pyrrolic-N species. The catalytic activity displays a volcano shape scaling relationship as a function of Cu particle size. Tribasic copper chloride is concomitantly generated with the construction of electron-deficient Cu sites. The H–Cl bond of HCl can be activated over the tribasic copper chloride, accelerating the surface reaction of vinyl chloride production. This strategy of inducing electron deficiency provides new insight into the rational design of catalysts for the synthesis of vinyl chloride with a high catalytic performance.展开更多
This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)w...This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.展开更多
In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The ...In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.展开更多
In the present work, the sulfur doped bismuth-based catalysts were prepared by incipient wetness impregnation method and used for the hydrochlorination of acetylene to vinyl chloride monomer （VCM） in a fixed-bed rea...In the present work, the sulfur doped bismuth-based catalysts were prepared by incipient wetness impregnation method and used for the hydrochlorination of acetylene to vinyl chloride monomer （VCM） in a fixed-bed reactor. The effect of introduction of S was characterized by N2 adsorption-desorption, powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, temperature-programmed reduction and X-ray photoelectron spectroscopy. The characterization results indicated that the doping of S resulted in the increase of Brunauer-Emmett-Teller （BET） surface areas and decrease of active species particle size for the Bi-based catalysts, which led to more accessible active sites, and consequently boosted the catalytic hydrochlorination activity. The effect of H2SO4 concentration on the activity of this type catalyst was examined, and the results showed that there is an optimal loading of H2SO4 （S/Bi=0.5 mol/mol）, at which the conversion of C2H2 was enhanced to 81% under the reaction condition and coke deposition is a main reason for the deactivation of catalyst.展开更多
Mercuric chloride supported on activated carbon(HgCl_2/AC) is used as an industrial catalyst for the hydrochlorination of acetylene. Loss of HgCl_2 by sublimating from the surface of activated carbon causes the irreve...Mercuric chloride supported on activated carbon(HgCl_2/AC) is used as an industrial catalyst for the hydrochlorination of acetylene. Loss of HgCl_2 by sublimating from the surface of activated carbon causes the irreversible deactivation of mercury catalyst and environmental pollution. In this work, a ligand coordination approach based on the Principle of Hard and Soft Acids and Bases(HSAB) was employed to design more stable lowmercury catalyst. The low-mercury catalysts(4% HgCl_2 loading) were prepared by using HgCl_2 and potassium halides(KX, X = Cl, I) as precursors. The HgCl_2-4KI/AC catalyst showed best catalytic stability than HgCl_2/AC and HgCl_2-4KCl/AC in the hydrochloriantion of acetylene. HgCl_2 could form more stable complex with KI,K_2HgI_4 as the main active component of the HgCl_2-4KI/AC catalyst. The characterizations of XRD and EDX analysis illustrated that the active component of HgCl_2-4KI/AC was highly dispersed on the surface of activated carbon.The sublimation rates of HgCl_2 from the catalysts verified that the active component with larger stability constant had better thermal stability. Using Hg(Ⅱ) complexes with high stability constant as the active component may be the research direction of developing highly stable low-mercury catalyst for the hydrochlorination of acetylene.展开更多
In this work,Bi-based catalysts were prepared by one pot method(PM)and incipient wetness impregnation method(IM)and preparation conditions of the PM were researched.Catalytic activity of catalysts was evaluated using ...In this work,Bi-based catalysts were prepared by one pot method(PM)and incipient wetness impregnation method(IM)and preparation conditions of the PM were researched.Catalytic activity of catalysts was evaluated using a fixed-bed reactor for acetylene hydrochlorination.The results displayed that the PM catalyst was prepared at 160℃for 2 h possessed a superior catalytic performance compared to the IM catalyst.The characterizations of XRD,BET,EDS and SEM demonstrated that the PM catalyst was microspheres structure,which could provide richer channel structures,larger specific surface areas and more active centres,thus improving the catalytic performances of catalysts.In addition,carbon deposition in the reaction was a possible reason for Bi-based catalysts deactivation.展开更多
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 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.
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.
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.
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(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 (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.
文摘The development of efficient and stable non-mercury catalysts for the chlor-alkali industry is desirable but remains a great challenge.Herein,we design a series of ruthenium catalysts for acetylene hydrochlorination by regulating the electronic structure of ruthenium ions through coordination with various ligands(thiourea,phenanthroline,and L-lactic).The turnover frequencies(TOFs)and apparent activation energies for the acetylene hydrochlorination have a linear relationship with the binding energy of Ru3+in the ruthenium catalysts.The synergetic effect of the ruthenium ion and ligands plays an important role in acetylene hydrochlorination.The Ru-Thi/AC catalyst with thiourea as the ligand shows the highest TOF and stability in acetylene hydrochlorination.The present study provides a rational method to regulate the electronic structure of supported metal catalysts with high catalytic performance exhibited by the carbon-supported heterogeneous catalysts.
文摘Herein,we report an excellent,supported Ru(III)‐ChCl/AC catalyst with lower Ru content,where the ionic complex ChRuCl4 serves as the active component for acetylene hydrochlorination.The prepared heterogeneous Ru‐10%ChCl/AC catalyst shows excellent activity and long‐term stability.In this system,ChCl provides an environment for the ChRuCl4 to be stabilized as Ru(III),thus suppressing the reduction of the active species and the aggregation of ruthenium species during the reaction.The interaction between reactants and catalyst species was investigated by catalyst characterizations in combination with DFT calculations to disclose the effect of the ChRuCl4 complex and ChCl on the catalytic performance.This inexpensive,efficient,and long‐term catalyst is a competitive candidate for application in the hydrochlorination industry.
文摘The activation of HCl by cationic Au in the presence of C2H2 is important for the construction of active Au sites and in acetylene hydrochlorination.Here,we report a strategy for activating HCl by the Au-based supported ionic liquid phase(Au–SILP)technology with the[N(CN)2^–]anion.This strategy enables HCl to accept electrons from[N(CN)2^–]anions in Au–[N(CN)2^–]complexes rather than from pure[Bmim][N(CN)2],leading to notable improvement in both the reaction path and the stability of the catalyst without changing the reaction triggered by acetylene adsorption.Furthermore,the induction period of the Au–SILP catalyst was shown to be absent in the reaction process due to the high Au(III)content in the Au(Ⅲ)/Au(Ⅰ)site and the high substrate diffusion rate in the ionic liquid layer.This work provides a facile method to improve the stability of Au-based catalysts for acetylene hydrochlorination.
基金supported by the National Key Technology R&D Program of China with Grant No.2011BAE03B07
文摘AuCl3 loaded structured catalysts were prepared on SiC foam supported with pre-coated activated carbon layers. The catalytic properties of the structured catalysts towards hydrochlorination of acetylene were tested in a fixed- bed reactor with the AuCl3 loaded on activated carbon pellets as a reference. For isopyknic catalysts, the structured catalyst with only one fifth of the Au amount as that was used on the reference catalyst exhibited even a little higher acetylene conversion and much better stability than the latter no matter what the gas hourly space velocities of acetylene were used. The results indicated that the more homogeneous distribution of AuCl3 particles and better heat transfer along the fixed-bed reactor originated from the low pressure drop and high thermal conductivity of the SiC foam supported structured catalysts might be able to account for their improved efficiency and stability. It is befieved that these novel structured C/Au catalysts can be potentially applied in VCM industrialization in view of their greatly reduced cost and much prolonged life.
文摘Activated carbon-supported mercuric chloride（HgCl2） is used as an industrial catalyst for acetylene hydrochlorination. However, the characteristic of easy sublimation of HgCl2 leads to the deactivation o the catalyst. Here, we showed that the thermal stability of the Hg/AC catalyst can be evidently improved when Cs Cl is added into the Hg/AC catalyst. Compared with the pure Hg/AC catalyst, the sublimation rate of HgCl2 from the Hg–Cs/AC catalyst decreased significantly and the Hg–Cs/AC catalyst showed bette catalytic activity and stability in the reaction. This promoting effect is related to the existence of cesium mercuric chlorides（CsxHgyCl（x＋2y）） highlighted by XRD, HR-TEM and EDX analyses. Thus, reacting HgCl2 with alkali chlorides to form alkali-mercuric chlorides may be a key to design highly efficient and thermally stable mercuric chloride catalyst for hydrochlorination reactions.
基金Zhejiang Provincial Natural Science Foundation of China(LY17B030010)~~
文摘We recently reported an N‐doped mesoporous carbon(N‐MC)extrudate,with major quaternary N species,prepared by a cheap and convenient method through direct carbonization of wheat flour with silica,which has excellent catalytic performance in acetylene hydrochlorination.Herein,we examined the activity of Au supported on N‐MC(Au/N‐MC)and compared it with that of Au supported on nitrogen‐free mesoporous carbon(Au/MC).The acetylene conversion of Au/N‐MC was 50%at 180°C with an acetylene space velocity of 600 h–1 and VHCl/VC2H2 of 1.1,which was double the activity of Au/MC(25%).The introduced nitrogen atoms acted as anchor sites that stabilized the Au3+species and inhibited the reduction of Au3+to Au0 during the preparation of Au/N‐MC catalysts.
基金Financial support from the National Natural Science Foundation of China (NSFCgrant No.U20A20119,21606199,22078302,52070035)+3 种基金the Science and Technology Department of Zhejiang Province (LGG20B060004)the China Postdoctoral Science Foundation (2020M671791)the Jilin Province Scientific and the Technological Planning Project of China (No.20200403001SF)the National Key Research and Development Program of China (2021YFA1501800,2021YFA1501801,2021YFA1501802)。
文摘Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by controlling the impregnation solutions. The π electrons flowing from acetylene to Cu site are facilitated over the electron-deficient Cu sites, achieving high activation of C≡C bond. The contradiction between the increased activation of acetylene required for enhanced catalytic activity and the resistance of Cu site to reduction by acetylene required for maintaining catalytic stability can be balanced by establishing strong interactions of Cu site with pyrrolic-N species. The catalytic activity displays a volcano shape scaling relationship as a function of Cu particle size. Tribasic copper chloride is concomitantly generated with the construction of electron-deficient Cu sites. The H–Cl bond of HCl can be activated over the tribasic copper chloride, accelerating the surface reaction of vinyl chloride production. This strategy of inducing electron deficiency provides new insight into the rational design of catalysts for the synthesis of vinyl chloride with a high catalytic performance.
基金supported by the Taishan Scholars Program of Shandong Province(tsqn202103051)the Project of Scientific Research in Shihezi University(CXFZ202205)。
文摘This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.
基金supported by the National Natural Science Foundation of China (NSFC,22172082,21978137,22102074,and 21878162)Natural Science Foundation of Tianjin (20JCZDJC00770)+1 种基金Postdoctoral Research Foundation of China (2021M701776)NCC Fund (NCC2020FH05)。
文摘In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.
基金supported by the National Natural Science Foundation of China(Nos.U1403293,21263025)the Graduate Research and Innovation Program of Xinjiang(No.XJGRI2015010)
文摘In the present work, the sulfur doped bismuth-based catalysts were prepared by incipient wetness impregnation method and used for the hydrochlorination of acetylene to vinyl chloride monomer （VCM） in a fixed-bed reactor. The effect of introduction of S was characterized by N2 adsorption-desorption, powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, temperature-programmed reduction and X-ray photoelectron spectroscopy. The characterization results indicated that the doping of S resulted in the increase of Brunauer-Emmett-Teller （BET） surface areas and decrease of active species particle size for the Bi-based catalysts, which led to more accessible active sites, and consequently boosted the catalytic hydrochlorination activity. The effect of H2SO4 concentration on the activity of this type catalyst was examined, and the results showed that there is an optimal loading of H2SO4 （S/Bi=0.5 mol/mol）, at which the conversion of C2H2 was enhanced to 81% under the reaction condition and coke deposition is a main reason for the deactivation of catalyst.
基金Supported by the National Natural Science Foundation of China(21476207)the China Postdoctoral Science Foundation(2016M592015)
文摘Mercuric chloride supported on activated carbon(HgCl_2/AC) is used as an industrial catalyst for the hydrochlorination of acetylene. Loss of HgCl_2 by sublimating from the surface of activated carbon causes the irreversible deactivation of mercury catalyst and environmental pollution. In this work, a ligand coordination approach based on the Principle of Hard and Soft Acids and Bases(HSAB) was employed to design more stable lowmercury catalyst. The low-mercury catalysts(4% HgCl_2 loading) were prepared by using HgCl_2 and potassium halides(KX, X = Cl, I) as precursors. The HgCl_2-4KI/AC catalyst showed best catalytic stability than HgCl_2/AC and HgCl_2-4KCl/AC in the hydrochloriantion of acetylene. HgCl_2 could form more stable complex with KI,K_2HgI_4 as the main active component of the HgCl_2-4KI/AC catalyst. The characterizations of XRD and EDX analysis illustrated that the active component of HgCl_2-4KI/AC was highly dispersed on the surface of activated carbon.The sublimation rates of HgCl_2 from the catalysts verified that the active component with larger stability constant had better thermal stability. Using Hg(Ⅱ) complexes with high stability constant as the active component may be the research direction of developing highly stable low-mercury catalyst for the hydrochlorination of acetylene.
基金Natural Scientific Foundation of China(21263025,U1403293)
文摘In this work,Bi-based catalysts were prepared by one pot method(PM)and incipient wetness impregnation method(IM)and preparation conditions of the PM were researched.Catalytic activity of catalysts was evaluated using a fixed-bed reactor for acetylene hydrochlorination.The results displayed that the PM catalyst was prepared at 160℃for 2 h possessed a superior catalytic performance compared to the IM catalyst.The characterizations of XRD,BET,EDS and SEM demonstrated that the PM catalyst was microspheres structure,which could provide richer channel structures,larger specific surface areas and more active centres,thus improving the catalytic performances of catalysts.In addition,carbon deposition in the reaction was a possible reason for Bi-based catalysts deactivation.
