In this study, the developments in modeling gas-phase catalyzed olefin polymerization fluidized-bed reactors （FBR） using Ziegler-Natta catalyst is presented. The modified mathematical model to account for mass and h...In this study, the developments in modeling gas-phase catalyzed olefin polymerization fluidized-bed reactors （FBR） using Ziegler-Natta catalyst is presented. The modified mathematical model to account for mass and heat transfer between the solid particles and the surrounding gas in the emulsion phase is developed in this work to include site activation reaction. This model developed in the present study is subsequently compared with well-known models, namely, the bubble-growth, well-mixed and the constant bubble size models for porous and non porous catalyst. The results we obtained from the model was very close to the constant bubble size model, well-mixed model and bubble growth model at the beginning of the reaction but its overall behavior changed and is closer to the well-mixed model compared with the bubble growth model and constant bubble size model after half an hour of operation. Neural-network based predictive controller are implemented to control the system and compared with the conventional PID controller, giving acceptable results.展开更多
For the rational design of metal catalyst in olefin polymerization catalysis,various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center,among which the"sa...For the rational design of metal catalyst in olefin polymerization catalysis,various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center,among which the"sandwich"type turned out to be an eficient category in achieving high molecular weight polyolefin.In the a-dimine system,the"sandwich"type catalysts were built using the typical 8-aryl-naphthyI framework.In this contribution,by introducing the rotationally restrained benzosuberyl substituent into the ortho-position of N-aryl rings,a new class of "sandwich-like"a-diimine nickel catalysts was constructed and fully identified.The rotationally restrained benzosuberyl substituents played a"sandwich-like"function by capping the nickel center from two axial sites.Compared to the nickel catalyst Ni1 bearing freely rotated benzhydryl substituent,Ni2 featuring benzosubery|substituent enabled the increase(8 times)of polymer molecular weights from 8 kDa to 65 kDa in the polymerization of ethylene.By further increasing the steric bulk of another ortho-site of the N-aryl ring,the polymer molecular weight even reached an ultrahigh level of 833 kDa(Mw=1857 kDa)using the optimized Ni3.Notably,these nickel catalysts could also mediate the copolymerization of ethylene with methyl 10-undecenoate,with Ni3 giving the highest copolymer molecular weight(88 kDa)and the highest incorporation of comonmer(2.0 mol1%),along with high activity of up to 10^(5)g·mol^(-1)·h^(-1).展开更多
An unbridged zirconocene complex bis(1,2-diphenylcyclopentadienyl)zirconium dichloride [(1,2-Ph2-C5H3)2ZrCl2] 1 has been synthesized and structurally characterized. When activated by MAO, 1 produces ultra-high molecul...An unbridged zirconocene complex bis(1,2-diphenylcyclopentadienyl)zirconium dichloride [(1,2-Ph2-C5H3)2ZrCl2] 1 has been synthesized and structurally characterized. When activated by MAO, 1 produces ultra-high molecular weight polyethylene with high melting transition temperature, as well as atactic oligopropylene with average molecular weight of ~1150 g mol-1.展开更多
The NdCl_3/MgCl_2 bisupported catalyst was prepared by using NdCl_3 ,MgCl_2, (CH_3)_2(CH_2)_2 OH and TiCl_4. It is shown that the structure of bisupported catalyst was different from those of either NdCl_3 or MgCl_2 s...The NdCl_3/MgCl_2 bisupported catalyst was prepared by using NdCl_3 ,MgCl_2, (CH_3)_2(CH_2)_2 OH and TiCl_4. It is shown that the structure of bisupported catalyst was different from those of either NdCl_3 or MgCl_2 single supported catalyst. A peculiar type of kinetic curve for ethylene polymerization was found.展开更多
Non-metallocene catalysts have emerged as a promising alternative to traditional metallocene catalysts for olefin polymerization,offering unique advantages regarding polymer structure control and product diversity.Rec...Non-metallocene catalysts have emerged as a promising alternative to traditional metallocene catalysts for olefin polymerization,offering unique advantages regarding polymer structure control and product diversity.Recent advancements in ligand design and synthesis have led to the development of highly active and selective non-metallocene catalysts capable of producing polyolefins with tailored properties.These catalysts exhibit enhanced thermal stability,improved comonomer incorporation,and the ability to polymerize a wider range of monomers.Furthermore,nonmetallocene catalysts have shown potential as promising compounds for the production of novel polymer architectures,including hyperbranched and stereoblock polymers.This work provides an overview of the current state of non-metallocene catalysts for olefin polymerization,examining their advantages,challenges,and future prospects in the field of polymer synthesis.展开更多
The well-defined Al-alkyl borate(AAB)salt{[iBu_(2)(PhNMe_(2))Al]_(2)(μ-H)}^(+)[B(C_(6)F_(5))_(4)]^(-)(AlHAl)has been recently identified as a promising“complete”cocatalyst for olefin polymerization.Herein,we explor...The well-defined Al-alkyl borate(AAB)salt{[iBu_(2)(PhNMe_(2))Al]_(2)(μ-H)}^(+)[B(C_(6)F_(5))_(4)]^(-)(AlHAl)has been recently identified as a promising“complete”cocatalyst for olefin polymerization.Herein,we explore structural variations of AlHAl obtained by replacing the PhNMe_(2)(DMA)donor with a variety of anilines,amines,and N-heterocycles.Of the 18 investigated N-donors,twelve provided stable AAB salts;these were tested as cocatalysts in ethylene/1-hexene copolymerization with an archetypical metallocene catalyst.展开更多
The ability to control catalytic activity via redox-activity has had a significant impact on the field of polymerization catalysis.Herein,we describe the synthesis of three unique Ni-based olefin polymerization cataly...The ability to control catalytic activity via redox-activity has had a significant impact on the field of polymerization catalysis.Herein,we describe the synthesis of three unique Ni-based olefin polymerization catalysts bearing redox-active α-diimine ligands.We will demonstrate that catalysts bearing butanedioneor glyoxal-derived ligands display little to no differentiation as a function of redox-state.However,in stark contrast we will show that the catalyst bearing an acenaphthenequinone-derived ligand is capable of producing either medium-density or very-low-density polyethylene based purely on its ligand-based redoxstate.This ability to access more than one polyethylene grade via a single redox-active catalyst is unprecedented.展开更多
Stiffening of the catalyst backbone of salan-type catalyst 1 via ring closure yields indanosalan 3 and increases activity and molar mass capability by two orders of magnitude.In propene polymerization,catalyst 3 is hi...Stiffening of the catalyst backbone of salan-type catalyst 1 via ring closure yields indanosalan 3 and increases activity and molar mass capability by two orders of magnitude.In propene polymerization,catalyst 3 is highly isotactic selective and nearly as active as one of the most productive known salan-catalysts today(2),showing much higher molar mass capability.NMR studies provide evidence of the identity of the active metal-polymeryl species for the catalyst pair 1/3,explaining their vast activity differences:the traditional salan catalyst 1 is trapped in the inactive mer–mer configuration,while indanosalan 3 prefers the active fac–fac isomer.展开更多
Polyolefins play an important role in modern society and are applied as both commodity plastics and high-performance polymers.Nowadays,they are widely used in large-scale industrial production and considered one among...Polyolefins play an important role in modern society and are applied as both commodity plastics and high-performance polymers.Nowadays,they are widely used in large-scale industrial production and considered one among the most important polymers in the world.Since the 1950s,the exploration of Ziegler-Natta catalysts has not just brought continuous breakthroughs in the industrialization of polyolefins,but has also promoted the development of research in organometallic chemistry.Obviously,a key and long-standing focus in the polyolefin industry is the investigation of new metal catalysts that possess customizable catalytic performances.Over the past few decades,metal complexes with N-heterocyclic carbene(NHC)ligands have achieved great improvements and found vast applications in diverse research fields,and definitely,they have been also demonstrated to show excellent catalytic performances in olefin polymerization.Numerous reviews have been published on the catalytic performances of NHC-chelated metal complexes;however,a comprehensive overview of them with the central metals across the periodic table in olefin polymerization is currently lacking.This review aims to bridge this gap by providing a comprehensive summary of NHC catalysts and their corresponding structure-activity relationships in the polymerization and copolymerization of different olefins.展开更多
Comprehensive Summary For coordination-insertion olefin polymerization,the development of novel transition-metal catalysts has drawn extensive attention in this field.In this contribution,we designed a series of hemil...Comprehensive Summary For coordination-insertion olefin polymerization,the development of novel transition-metal catalysts has drawn extensive attention in this field.In this contribution,we designed a series of hemilabileα-diimine nickel catalysts bearing oxygen atom as neighboring group.The steric hindrance and oxygen atom number of these nickel complexes(Ni1—Ni4)could be adjusted,which influenced ethylene(co)polymerization processes.展开更多
The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses o...The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses on the transition metal complex catalyst with high thermal stability containing different structures,including the backbone of bis（imino）pyridine,a-diimine and other types of ligands.Besides the catalytic activity,the influence of reaction temperature on the molecular weight and molecular weight distribution of the obtained polymer was also described.The plausible mechanism on the stability of catalysts at high temperature was proposed,which may give guidance to design catalyst with good thermal stability.展开更多
In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor,...In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed.展开更多
Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst ...Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst system is rare thus far.In this contribution,by introducing different backbones,flexible and rigid axial substituents into theα-imino-ketone framework,a family of cationic nickel catalysts were synthesized and fully characterized.Without the addition of any activator,systematic studies on ethylene polymerization and copolymerization with polar monomers were performed to explore the influence of both backbone and axial substituent on catalytic activity,polymer molecular weight,branching density and incorporation.In particular,owing to the unique semi-opening feature of theα-imino-ketone framework,the preferred nickel catalyst exhibited high activity of 175 kg·mol^(-1)·h^(-1)to produce functionalized polyethylene with molecular weight of 13.4 kg·mol^(-1)and comonomer incorporation of 2.9 mol%.展开更多
Brookhart-typeα-diimine nickel and palladium catalysts have been extensively studied over the past several decades;however,the heterogenization of these metal complexes has received much less attention.In this contri...Brookhart-typeα-diimine nickel and palladium catalysts have been extensively studied over the past several decades;however,the heterogenization of these metal complexes has received much less attention.In this contribution,we installed a trifluoroborate potassium substituent on anα-diimine framework.The ionic nature of trifluoroborate potassium endowed theα-diimine nickel complex with a strong affinity for the SiO_(2)support,while its electron-donating nature enhanced the catalyst stability and polyethylene molecular weight.In the presence of only 100 equiv.of Et2AlCl cocatalyst,the SiO_(2)-supported catalyst demonstrated significantly better performance than its homogeneous analog during ethylene polymerization,with extremely high activity(1.42–6.53×10^(7)g mol^(−1)h^(−1))and high thermal stability.The heterogeneous system led to the formation of high-molecular-weight polyethylenes(Mn 142,500–732,800 g/mol),narrow polydispersities(2.18–3.00),tunable branching densities(21–64 per 1000 carbon atoms),and great mechanical properties.Moreover,the efficient copolymerization of ethylene with comonomers such as methyl 10-undecenoate,6-chloro-1-hexene or 5-hexenylacetate was achieved.These superior properties enabled by the trifluoroborate potassium moiety may inspire its applications in other polymerization catalyst systems.展开更多
Ethylene polymerization was carried out by immobilization of rac-ethylenebis（1-indenyl）zirconium dichloride （Et（Ind）2ZrCl2） and rac-dimethylsilylbis（1-indenyl）zirconium dichloride （Me2Si（Ind）2ZrCl2） preact...Ethylene polymerization was carried out by immobilization of rac-ethylenebis（1-indenyl）zirconium dichloride （Et（Ind）2ZrCl2） and rac-dimethylsilylbis（1-indenyl）zirconium dichloride （Me2Si（Ind）2ZrCl2） preactivated with methylaluminoxane （MAO） on calcinated silica at different temperatures. Polymerizations of ethylene were conducted at different temperatures to find the optimized polymerization temperature for maximum activity of the catalyst. The Me2Si bridge catalyst showed higher activity at the lower polymerization temperature compared to the Et bridge catalyst. The highest catalytic activities were obtained at temperatures about 50 ~C and 70 ~C for Me2Si（Ind）2ZrC1JMAO and Et（Ind）zZrCI2/MAO catalysts systems, respectively. Inductively coupled plasma-atomic emission spectroscopy results and polymerization activity results confirmed that the best temperature for calcinating silica was about 450 ℃ for both catalysts systems. The melting points of the produced polyethylene were about 130 ℃, which could be attributed to the linear structure of HDPE.展开更多
The development of degradable polymers represents an appealing strategy to address ever-growing concerns for treating waste plastics.Olefin metathesis polymerization has been extensively explored for the synthesis of ...The development of degradable polymers represents an appealing strategy to address ever-growing concerns for treating waste plastics.Olefin metathesis polymerization has been extensively explored for the synthesis of various degradable polymers.Cyclic–acyclic monomers metathesis polymerization(CAMMP)has recently been reported to produce degradable polymers via copolymerization of cyclic monomers with acyclic diene comonomers.Unfortunately,this strategy suffers from poor product material properties,especially at high contents of diene comonomers.To address this issue,we have designed a tandem olefin metathesis polymerization(TOMP)system that combines olefin ringclosing metathesis(RCM)of diene comonomers,followed by ring-opening metathesis copolymerization(ROMCP)with cyclic olefin monomers(dicyclopentadiene,cyclooctene,or alkyl-substituted cyclooctene).This strategy overcame the intrinsic limitations of diene-induced chain-transfer reactions during olefin metathesis,leading to degradable polymers with high molecular weights and excellent material properties.The selection of different cyclic olefin monomers provided access to degradable and recyclable cross-linked thermosets,linear thermoplastics,and elastomers.Notably,this one-pot,two-step process was highly efficient and required the addition of only one metathesis catalyst.展开更多
Metal-catalyzed ethylene homopolymerization and ethylene-polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for tr...Metal-catalyzed ethylene homopolymerization and ethylene-polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for traditional transition metal catalyst systems. Therefore, it is critical to develop new catalysts or alternative strategies. In recent years, some cationic [P, O] palladium complexes have been demonstrated with the abilities to obtain oligomers and the high molecular weight polymers. Most importantly, these complexes showed high activity and generated polymers with specific microstructures when used for copolymerization of ethylene with industrially relevant polar monomers. This review summarizes several types of high performance cationic [P, O] palladium catalysts in ethylene oligomerization, ethylene homopolymerization and the copolymerization of ethylene with polar monomers Specially, the regulation of steric and electronic effects at specific sites of the metal complexes was focused.展开更多
In recent years,production of engine fuels and energy from biomass has drawn much interest.In this work,we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic b...In recent years,production of engine fuels and energy from biomass has drawn much interest.In this work,we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic biomass pyrolysis-oil(bio-oil).The process includes(i)the production of bio-hydrogen or bio-syngas by the catalytic cracking of bio-oil,(ii)the adjustment of bio-syngas,and(iii)the production of bio-fuels by ole nic polymerization(OP)together with Fischer-Tropsch synthesis(FTS).Under the optimal conditions,the yield of bio-hydrogen was 120.9 g H2/(kg bio-oil).The yield of hydrocarbon bio-fuels reached 526.1 g/(kg bio-syngas)by the coupling of OP and FTS.The main reaction pathways(or chemical processes)were discussed based on the products observed and the catalyst property.展开更多
文摘In this study, the developments in modeling gas-phase catalyzed olefin polymerization fluidized-bed reactors （FBR） using Ziegler-Natta catalyst is presented. The modified mathematical model to account for mass and heat transfer between the solid particles and the surrounding gas in the emulsion phase is developed in this work to include site activation reaction. This model developed in the present study is subsequently compared with well-known models, namely, the bubble-growth, well-mixed and the constant bubble size models for porous and non porous catalyst. The results we obtained from the model was very close to the constant bubble size model, well-mixed model and bubble growth model at the beginning of the reaction but its overall behavior changed and is closer to the well-mixed model compared with the bubble growth model and constant bubble size model after half an hour of operation. Neural-network based predictive controller are implemented to control the system and compared with the conventional PID controller, giving acceptable results.
基金the National Natural Science Foundation of China(Nos.21871250 and 22001244)the Jilin Provincial Science and Technology Department Program(No.20200801009GH).
文摘For the rational design of metal catalyst in olefin polymerization catalysis,various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center,among which the"sandwich"type turned out to be an eficient category in achieving high molecular weight polyolefin.In the a-dimine system,the"sandwich"type catalysts were built using the typical 8-aryl-naphthyI framework.In this contribution,by introducing the rotationally restrained benzosuberyl substituent into the ortho-position of N-aryl rings,a new class of "sandwich-like"a-diimine nickel catalysts was constructed and fully identified.The rotationally restrained benzosuberyl substituents played a"sandwich-like"function by capping the nickel center from two axial sites.Compared to the nickel catalyst Ni1 bearing freely rotated benzhydryl substituent,Ni2 featuring benzosubery|substituent enabled the increase(8 times)of polymer molecular weights from 8 kDa to 65 kDa in the polymerization of ethylene.By further increasing the steric bulk of another ortho-site of the N-aryl ring,the polymer molecular weight even reached an ultrahigh level of 833 kDa(Mw=1857 kDa)using the optimized Ni3.Notably,these nickel catalysts could also mediate the copolymerization of ethylene with methyl 10-undecenoate,with Ni3 giving the highest copolymer molecular weight(88 kDa)and the highest incorporation of comonmer(2.0 mol1%),along with high activity of up to 10^(5)g·mol^(-1)·h^(-1).
文摘An unbridged zirconocene complex bis(1,2-diphenylcyclopentadienyl)zirconium dichloride [(1,2-Ph2-C5H3)2ZrCl2] 1 has been synthesized and structurally characterized. When activated by MAO, 1 produces ultra-high molecular weight polyethylene with high melting transition temperature, as well as atactic oligopropylene with average molecular weight of ~1150 g mol-1.
文摘The NdCl_3/MgCl_2 bisupported catalyst was prepared by using NdCl_3 ,MgCl_2, (CH_3)_2(CH_2)_2 OH and TiCl_4. It is shown that the structure of bisupported catalyst was different from those of either NdCl_3 or MgCl_2 single supported catalyst. A peculiar type of kinetic curve for ethylene polymerization was found.
文摘Non-metallocene catalysts have emerged as a promising alternative to traditional metallocene catalysts for olefin polymerization,offering unique advantages regarding polymer structure control and product diversity.Recent advancements in ligand design and synthesis have led to the development of highly active and selective non-metallocene catalysts capable of producing polyolefins with tailored properties.These catalysts exhibit enhanced thermal stability,improved comonomer incorporation,and the ability to polymerize a wider range of monomers.Furthermore,nonmetallocene catalysts have shown potential as promising compounds for the production of novel polymer architectures,including hyperbranched and stereoblock polymers.This work provides an overview of the current state of non-metallocene catalysts for olefin polymerization,examining their advantages,challenges,and future prospects in the field of polymer synthesis.
基金forms part of the research program of DPI(project 857)Part of this work has been funded by the European Union-NextGenerationEU under the Italian Ministry of University and Research(MUR)National Innovation Ecosystem grant ECS00000041-VITALITY.We acknowledge Universitàdegli Studi di Perugia and MUR for support within the project Vitality+1 种基金A.M.and C.Z.thank the“FASTTO0”project(CUP J93C22000330006)funded through the Italian Ministry of Environment and Energy Security.The authors thank Dr Martina Landrini for support with crystallographic determinations.F.Z.thanks the Federico II University of Naples and PON-Ricerca e Innovazione(DM 1062)for a research fellowship。
文摘The well-defined Al-alkyl borate(AAB)salt{[iBu_(2)(PhNMe_(2))Al]_(2)(μ-H)}^(+)[B(C_(6)F_(5))_(4)]^(-)(AlHAl)has been recently identified as a promising“complete”cocatalyst for olefin polymerization.Herein,we explore structural variations of AlHAl obtained by replacing the PhNMe_(2)(DMA)donor with a variety of anilines,amines,and N-heterocycles.Of the 18 investigated N-donors,twelve provided stable AAB salts;these were tested as cocatalysts in ethylene/1-hexene copolymerization with an archetypical metallocene catalyst.
基金the Army Research Office(contract#:W911NF-1-0127)for their financial support of this work.
文摘The ability to control catalytic activity via redox-activity has had a significant impact on the field of polymerization catalysis.Herein,we describe the synthesis of three unique Ni-based olefin polymerization catalysts bearing redox-active α-diimine ligands.We will demonstrate that catalysts bearing butanedioneor glyoxal-derived ligands display little to no differentiation as a function of redox-state.However,in stark contrast we will show that the catalyst bearing an acenaphthenequinone-derived ligand is capable of producing either medium-density or very-low-density polyethylene based purely on its ligand-based redoxstate.This ability to access more than one polyethylene grade via a single redox-active catalyst is unprecedented.
基金The work of ADA,CZ,AV,CE,RC,AM and VB forms part of the research programme of DPI,project#835the European Union-NextGenerationEU under the Italian Ministry of University and Research(MUR)National Innovation Ecosystem grant ECS00000041-VITALITY for supporting this work+1 种基金Universitàdegli Studi di Perugia and MUR for support within the project VitalityDVU,MIS,GPG,KML,and AZV thank Ministry of Science and Higher Education for support of their work(project#121021000105-7)。
文摘Stiffening of the catalyst backbone of salan-type catalyst 1 via ring closure yields indanosalan 3 and increases activity and molar mass capability by two orders of magnitude.In propene polymerization,catalyst 3 is highly isotactic selective and nearly as active as one of the most productive known salan-catalysts today(2),showing much higher molar mass capability.NMR studies provide evidence of the identity of the active metal-polymeryl species for the catalyst pair 1/3,explaining their vast activity differences:the traditional salan catalyst 1 is trapped in the inactive mer–mer configuration,while indanosalan 3 prefers the active fac–fac isomer.
基金the financial support from the National Natural Science Fund for Distinguished Young Scholars of China(No.22025107)the Shaanxi Fundamental Science Research Project for Chemistry&Biology(No.22JHZ003)+1 种基金the National Youth Top-notch Talent Support Program of China,the Key International Scientific and Technological Cooperation and Exchange Project of Shaanxi Province(No.2023-GHZD-15)Xi’an Key Laboratory of Functional Supramolecular Structure and Materials,and the FM&EM International Joint Laboratory of Northwest University.
文摘Polyolefins play an important role in modern society and are applied as both commodity plastics and high-performance polymers.Nowadays,they are widely used in large-scale industrial production and considered one among the most important polymers in the world.Since the 1950s,the exploration of Ziegler-Natta catalysts has not just brought continuous breakthroughs in the industrialization of polyolefins,but has also promoted the development of research in organometallic chemistry.Obviously,a key and long-standing focus in the polyolefin industry is the investigation of new metal catalysts that possess customizable catalytic performances.Over the past few decades,metal complexes with N-heterocyclic carbene(NHC)ligands have achieved great improvements and found vast applications in diverse research fields,and definitely,they have been also demonstrated to show excellent catalytic performances in olefin polymerization.Numerous reviews have been published on the catalytic performances of NHC-chelated metal complexes;however,a comprehensive overview of them with the central metals across the periodic table in olefin polymerization is currently lacking.This review aims to bridge this gap by providing a comprehensive summary of NHC catalysts and their corresponding structure-activity relationships in the polymerization and copolymerization of different olefins.
基金supported by National Key R&D Program of China(No.2021YFA1501700)Natural Science Foundation of Anhui Province(2308085Y35,2023AH030002)+2 种基金Hefei Natural Science Foundation(202304)CAS Project for Young Scientists in Basic Research(No.YSBR-094)2023 Youth Innovation Foundation ofUniversity of Science and Technologyof China(WK2060000074).
文摘Comprehensive Summary For coordination-insertion olefin polymerization,the development of novel transition-metal catalysts has drawn extensive attention in this field.In this contribution,we designed a series of hemilabileα-diimine nickel catalysts bearing oxygen atom as neighboring group.The steric hindrance and oxygen atom number of these nickel complexes(Ni1—Ni4)could be adjusted,which influenced ethylene(co)polymerization processes.
文摘The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses on the transition metal complex catalyst with high thermal stability containing different structures,including the backbone of bis（imino）pyridine,a-diimine and other types of ligands.Besides the catalytic activity,the influence of reaction temperature on the molecular weight and molecular weight distribution of the obtained polymer was also described.The plausible mechanism on the stability of catalysts at high temperature was proposed,which may give guidance to design catalyst with good thermal stability.
基金This work was supported by the National Natural Science Foundation of China
文摘In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed.
基金financially supported by the National Natural Science Foundation of China(Nos.22122110,21871250 and 22001244)the Jilin Provincial Science and Technology Department Program(No.20200801009GH)。
文摘Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst system is rare thus far.In this contribution,by introducing different backbones,flexible and rigid axial substituents into theα-imino-ketone framework,a family of cationic nickel catalysts were synthesized and fully characterized.Without the addition of any activator,systematic studies on ethylene polymerization and copolymerization with polar monomers were performed to explore the influence of both backbone and axial substituent on catalytic activity,polymer molecular weight,branching density and incorporation.In particular,owing to the unique semi-opening feature of theα-imino-ketone framework,the preferred nickel catalyst exhibited high activity of 175 kg·mol^(-1)·h^(-1)to produce functionalized polyethylene with molecular weight of 13.4 kg·mol^(-1)and comonomer incorporation of 2.9 mol%.
基金supported by National Key R&D Program of China(No.2021YFA1501700)National Natural Science Foundation of China(Nos.52025031,U19B6001 and U1904212)K.C.Wong Education Foundation.
文摘Brookhart-typeα-diimine nickel and palladium catalysts have been extensively studied over the past several decades;however,the heterogenization of these metal complexes has received much less attention.In this contribution,we installed a trifluoroborate potassium substituent on anα-diimine framework.The ionic nature of trifluoroborate potassium endowed theα-diimine nickel complex with a strong affinity for the SiO_(2)support,while its electron-donating nature enhanced the catalyst stability and polyethylene molecular weight.In the presence of only 100 equiv.of Et2AlCl cocatalyst,the SiO_(2)-supported catalyst demonstrated significantly better performance than its homogeneous analog during ethylene polymerization,with extremely high activity(1.42–6.53×10^(7)g mol^(−1)h^(−1))and high thermal stability.The heterogeneous system led to the formation of high-molecular-weight polyethylenes(Mn 142,500–732,800 g/mol),narrow polydispersities(2.18–3.00),tunable branching densities(21–64 per 1000 carbon atoms),and great mechanical properties.Moreover,the efficient copolymerization of ethylene with comonomers such as methyl 10-undecenoate,6-chloro-1-hexene or 5-hexenylacetate was achieved.These superior properties enabled by the trifluoroborate potassium moiety may inspire its applications in other polymerization catalyst systems.
基金financially supported by the National Iranian Petrochemical Company Research and Technology(NIPC-RT)
文摘Ethylene polymerization was carried out by immobilization of rac-ethylenebis（1-indenyl）zirconium dichloride （Et（Ind）2ZrCl2） and rac-dimethylsilylbis（1-indenyl）zirconium dichloride （Me2Si（Ind）2ZrCl2） preactivated with methylaluminoxane （MAO） on calcinated silica at different temperatures. Polymerizations of ethylene were conducted at different temperatures to find the optimized polymerization temperature for maximum activity of the catalyst. The Me2Si bridge catalyst showed higher activity at the lower polymerization temperature compared to the Et bridge catalyst. The highest catalytic activities were obtained at temperatures about 50 ~C and 70 ~C for Me2Si（Ind）2ZrC1JMAO and Et（Ind）zZrCI2/MAO catalysts systems, respectively. Inductively coupled plasma-atomic emission spectroscopy results and polymerization activity results confirmed that the best temperature for calcinating silica was about 450 ℃ for both catalysts systems. The melting points of the produced polyethylene were about 130 ℃, which could be attributed to the linear structure of HDPE.
基金supported by National Key R&D Program of China(grant no.2021YFA1501700)National Natural Science Foundation of China(NSFC+3 种基金grant nos.22301294,52025031,and 22261142664)the Chinese Academy of Sciences(CAS)Project for Young Scientists in Basic Research(grant no.YSBR-094)China Postdoctoral Science Foundation(grant nos.BX20230339 and 2023M743352)the University of Science and Technology of China(USTC)Research Funds of the Double First-Class Initiative(grant no.YD9990002030).
文摘The development of degradable polymers represents an appealing strategy to address ever-growing concerns for treating waste plastics.Olefin metathesis polymerization has been extensively explored for the synthesis of various degradable polymers.Cyclic–acyclic monomers metathesis polymerization(CAMMP)has recently been reported to produce degradable polymers via copolymerization of cyclic monomers with acyclic diene comonomers.Unfortunately,this strategy suffers from poor product material properties,especially at high contents of diene comonomers.To address this issue,we have designed a tandem olefin metathesis polymerization(TOMP)system that combines olefin ringclosing metathesis(RCM)of diene comonomers,followed by ring-opening metathesis copolymerization(ROMCP)with cyclic olefin monomers(dicyclopentadiene,cyclooctene,or alkyl-substituted cyclooctene).This strategy overcame the intrinsic limitations of diene-induced chain-transfer reactions during olefin metathesis,leading to degradable polymers with high molecular weights and excellent material properties.The selection of different cyclic olefin monomers provided access to degradable and recyclable cross-linked thermosets,linear thermoplastics,and elastomers.Notably,this one-pot,two-step process was highly efficient and required the addition of only one metathesis catalyst.
基金Acknowledgement This work was supported by the National Natural Science Foundation of China （NSFC, No. 21304054）, the Taishan Scholar Foundation, Foundation of Qufu Normal University （No. xkJ201603）, and the National College Students Innovation Project （No. 201610446029）.
文摘Metal-catalyzed ethylene homopolymerization and ethylene-polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for traditional transition metal catalyst systems. Therefore, it is critical to develop new catalysts or alternative strategies. In recent years, some cationic [P, O] palladium complexes have been demonstrated with the abilities to obtain oligomers and the high molecular weight polymers. Most importantly, these complexes showed high activity and generated polymers with specific microstructures when used for copolymerization of ethylene with industrially relevant polar monomers. This review summarizes several types of high performance cationic [P, O] palladium catalysts in ethylene oligomerization, ethylene homopolymerization and the copolymerization of ethylene with polar monomers Specially, the regulation of steric and electronic effects at specific sites of the metal complexes was focused.
文摘In recent years,production of engine fuels and energy from biomass has drawn much interest.In this work,we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic biomass pyrolysis-oil(bio-oil).The process includes(i)the production of bio-hydrogen or bio-syngas by the catalytic cracking of bio-oil,(ii)the adjustment of bio-syngas,and(iii)the production of bio-fuels by ole nic polymerization(OP)together with Fischer-Tropsch synthesis(FTS).Under the optimal conditions,the yield of bio-hydrogen was 120.9 g H2/(kg bio-oil).The yield of hydrocarbon bio-fuels reached 526.1 g/(kg bio-syngas)by the coupling of OP and FTS.The main reaction pathways(or chemical processes)were discussed based on the products observed and the catalyst property.
