The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),an...The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),and polypropylene(PP).We report a catalytic aerobic oxidative approach for polyolefins upcycling with the corresponding carboxylic acids as the product.This method encompasses three key innovations.First,it operates under atmospheric pressure and mild conditions,using O_(2) or air as the oxidant.Second,it is compatible with high-density polyethylene,low-density polyethylene,PS,PP,and their blends.Third,it uses an economical and recoverable metal catalyst.It has been demonstrated that this approach can efficiently degrade mixed wastes of plastic bags,bottles,masks,and foam boxes.展开更多
Pd(OAc)_(2) is an extensively utilized palladium source in the palladium initiated transformations either directly or as a catalyst precursor. However, the comprehension of the real structure of Pd(OAc)_(2) in solutio...Pd(OAc)_(2) is an extensively utilized palladium source in the palladium initiated transformations either directly or as a catalyst precursor. However, the comprehension of the real structure of Pd(OAc)_(2) in solution is still vague. In this work, the structure of palladium acetate in solution was studied in detail by using X-ray absorption fine structure (XAFS) spectroscopy. The results demonstrate that monomer is the main form for Pd(OAc)_(2) in the solution of 1,4-dioxane, N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), 1,2-dimethoxyethane (DME), MeCN and dimethyl sulfoxide (DMSO). In addition, Pd(II) could be reduced to Pd(0) in ethanol solution. The structural information in this research will benefit the understanding of the mechanism of Pd(OAc)_(2) involved organic reactions.展开更多
Mechanistic studies of the palladium catalyst activation with halide additives are of great importance to palladium catalysis.In this work,XAFS spectroscopy and cyclic voltammetry were utilized to study real structure...Mechanistic studies of the palladium catalyst activation with halide additives are of great importance to palladium catalysis.In this work,XAFS spectroscopy and cyclic voltammetry were utilized to study real structures of Pd(OAc)2 in solution with different inorgan-ic halogen additives.XAFS results demonstrate that Pd maintained+2 in the presence of excessive LiCl,LiBr,ZnCl_(2),ZnBr_(2),and Nal.Fitting results of EXAFS spectra revealed that the Pd's first shell is replaced by halogen partially or completely depending on the hal-ogen species.DFT calculations were conducted to identify the most reliable solvated structures.The combined experimental and computational studies elucidate the critical role of inorganic halide additives in Pd chemistry.展开更多
基金We acknowledge the NSFC(Nos.22293014,22131002,22161142019)the National Key R&D Program of China(No.2021YFA1501700)+2 种基金the New Cornerstone Science Foundation through the XPLORER PRIZE for financial support.We would also like to thank our colleagues Prof.Jian Pei,Prof.Rong Zhu,and Prof.Aiwen Lei for sharing their instruments and helpful suggestionsDr.Zhenjin Liang and Ms.Qinqin Wei for their helpful discussionsand Mr.Zhenpeng Wang for his help in the analytical testing.
文摘The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),and polypropylene(PP).We report a catalytic aerobic oxidative approach for polyolefins upcycling with the corresponding carboxylic acids as the product.This method encompasses three key innovations.First,it operates under atmospheric pressure and mild conditions,using O_(2) or air as the oxidant.Second,it is compatible with high-density polyethylene,low-density polyethylene,PS,PP,and their blends.Third,it uses an economical and recoverable metal catalyst.It has been demonstrated that this approach can efficiently degrade mixed wastes of plastic bags,bottles,masks,and foam boxes.
基金This work was supported by the National Natural Science Foundation of China(No.21520102003)the Hubei Province Natural Science Foundation of China(No.2017CFA010)The Program of Introducing Talents of Discipline to Universities of China(111 Program)is also appreciated.All the XAFS data were collect-ed at beam line 44A of the TPS.
文摘Pd(OAc)_(2) is an extensively utilized palladium source in the palladium initiated transformations either directly or as a catalyst precursor. However, the comprehension of the real structure of Pd(OAc)_(2) in solution is still vague. In this work, the structure of palladium acetate in solution was studied in detail by using X-ray absorption fine structure (XAFS) spectroscopy. The results demonstrate that monomer is the main form for Pd(OAc)_(2) in the solution of 1,4-dioxane, N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), 1,2-dimethoxyethane (DME), MeCN and dimethyl sulfoxide (DMSO). In addition, Pd(II) could be reduced to Pd(0) in ethanol solution. The structural information in this research will benefit the understanding of the mechanism of Pd(OAc)_(2) involved organic reactions.
基金supported by the National Natural Science Foundation of China(No.22031008)the Science Foundationof Wuhan(No.2020010601012192).
文摘Mechanistic studies of the palladium catalyst activation with halide additives are of great importance to palladium catalysis.In this work,XAFS spectroscopy and cyclic voltammetry were utilized to study real structures of Pd(OAc)2 in solution with different inorgan-ic halogen additives.XAFS results demonstrate that Pd maintained+2 in the presence of excessive LiCl,LiBr,ZnCl_(2),ZnBr_(2),and Nal.Fitting results of EXAFS spectra revealed that the Pd's first shell is replaced by halogen partially or completely depending on the hal-ogen species.DFT calculations were conducted to identify the most reliable solvated structures.The combined experimental and computational studies elucidate the critical role of inorganic halide additives in Pd chemistry.
