A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid(2,4-D)was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprint...A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid(2,4-D)was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR,nitrogen adsorption and static adsorption experiments.The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol(2,4-DCP)mixture or using an aqueous 2,4-D and 2,4-dichlorophenylacetic acid(DPAC)mixture.The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18,the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9.The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent.The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D,73%of binding capacity(200 mg/L 2,4-D onto 20 mg of imprinted sorbent)was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol/L HC1(V:V=1:1).In a test of five extraction/stripping cycles,the adsorption capacity of the sorbent was all above 93%of that of the fresh sorbent.Experimental result showed the potential of molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-D.展开更多
Pd catalysts suffered from poor selectivity and stability for liquid-phase hydrogenation of maleic anhydride（MA） to gamma-butyrolactone（GBL）.Thus,Pd/C catalysts modified with different Sn loadings were synthesized...Pd catalysts suffered from poor selectivity and stability for liquid-phase hydrogenation of maleic anhydride（MA） to gamma-butyrolactone（GBL）.Thus,Pd/C catalysts modified with different Sn loadings were synthesized,and characterized by XRD,XPS,TEM and elemental mapping.The types of alloy phase and the amounts of the surface Pd-SnOx sites altered along with Sn/Pd mass ratios from 0-1.0synthesized in the process of preparation.The maximum reaction rate was 0.57 mol-GBL/（mol-Pd min）and selectivity was 95.94%when the Sn/Pd mass ratio was 0.6.It might be attributed to the formation of Pd2Sn alloy and less amounts of Pd-SnOx sites.展开更多
Semi-hydrogenation of acetylene is of growing interest and popularity but subjects to a major challenge in selective hydrogenation to ethylene.Here,we report a strategy that uses graphdiyne(GDY)as a carrier to prepare...Semi-hydrogenation of acetylene is of growing interest and popularity but subjects to a major challenge in selective hydrogenation to ethylene.Here,we report a strategy that uses graphdiyne(GDY)as a carrier to prepare single-cluster catalysts(SCCs),which on average clusters composed of three atoms(denoted as Pd3 trimer)and applied it to the acetylene semihydrogenation in the presence of large amounts of ethylene.Based on experimental results and systematic quantum chemical research and computational screening,we found that there are multiple active Pd structures on GDY and the Pd3 trimer anchored on GDY is a specific and durable cluster with great potential for accurate and efficient heterogeneous catalysis.The synergetic effects between neighboring atoms in Pd trimer guarantee easy desorption of ethylene and the absence of unselective hydride species thereby preventing excessive hydrogenation to generate unwanted byproducts,which is a crucial mechanism for the excellent selectivity of the catalyst.This new method for precise synthesis Pd clusters provides accurate ways for designing selective hydrogenation catalysts at the atomic scale.展开更多
基金supported by the Natural Science Foundation of Zhejiang Province(No.Y505073)the Scientific Project of Zhejiang Province(No.2008C22012)
文摘A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid(2,4-D)was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR,nitrogen adsorption and static adsorption experiments.The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol(2,4-DCP)mixture or using an aqueous 2,4-D and 2,4-dichlorophenylacetic acid(DPAC)mixture.The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18,the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9.The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent.The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D,73%of binding capacity(200 mg/L 2,4-D onto 20 mg of imprinted sorbent)was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol/L HC1(V:V=1:1).In a test of five extraction/stripping cycles,the adsorption capacity of the sorbent was all above 93%of that of the fresh sorbent.Experimental result showed the potential of molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-D.
基金supported by the National Natural Science Foundation,China(Nos.21506138,21606199,21575097 and21375092)the Natural Science Foundation of Zhejiang Province,China(No.LQ15B060001)the China Postdoctoral Science Foundation(No.2016M592015)
文摘Pd catalysts suffered from poor selectivity and stability for liquid-phase hydrogenation of maleic anhydride（MA） to gamma-butyrolactone（GBL）.Thus,Pd/C catalysts modified with different Sn loadings were synthesized,and characterized by XRD,XPS,TEM and elemental mapping.The types of alloy phase and the amounts of the surface Pd-SnOx sites altered along with Sn/Pd mass ratios from 0-1.0synthesized in the process of preparation.The maximum reaction rate was 0.57 mol-GBL/（mol-Pd min）and selectivity was 95.94%when the Sn/Pd mass ratio was 0.6.It might be attributed to the formation of Pd2Sn alloy and less amounts of Pd-SnOx sites.
基金the National Key Research and Development Program of China(Nos.2021YFA1501800,2021YFA1501801,and 2021YFA1501802)the Science and Technology Department of Zhejiang Province(No.LGG20B060004)+1 种基金the Zhejiang Province Public Welfare Technology Application Research Project(No.LGF19B050002)the National Natural Science Foundation of China(Nos.21606199 and 21976129)are gratefully acknowledged.
文摘Semi-hydrogenation of acetylene is of growing interest and popularity but subjects to a major challenge in selective hydrogenation to ethylene.Here,we report a strategy that uses graphdiyne(GDY)as a carrier to prepare single-cluster catalysts(SCCs),which on average clusters composed of three atoms(denoted as Pd3 trimer)and applied it to the acetylene semihydrogenation in the presence of large amounts of ethylene.Based on experimental results and systematic quantum chemical research and computational screening,we found that there are multiple active Pd structures on GDY and the Pd3 trimer anchored on GDY is a specific and durable cluster with great potential for accurate and efficient heterogeneous catalysis.The synergetic effects between neighboring atoms in Pd trimer guarantee easy desorption of ethylene and the absence of unselective hydride species thereby preventing excessive hydrogenation to generate unwanted byproducts,which is a crucial mechanism for the excellent selectivity of the catalyst.This new method for precise synthesis Pd clusters provides accurate ways for designing selective hydrogenation catalysts at the atomic scale.
