Organic structure directingagents(OSDAs),suchas tetrapropylammonium(TPA)cations,serve as crucial templates for the formation of zeolite frameworks.These organic molecules interact with inorganic species,guiding the as...Organic structure directingagents(OSDAs),suchas tetrapropylammonium(TPA)cations,serve as crucial templates for the formation of zeolite frameworks.These organic molecules interact with inorganic species,guiding the assembly of the zeolite structure.In this study,we inves-tigate the complex interplay between boron species and TPA cations during the crystallization of[B,Al]-ZSM-5 zeolites.Two-dimensional(2D)11B-{1H}cross-polarization heteronuclear correlation(CP-HECTOR)NMRexperiments elucidate distinct interactions between two boron species,B(IV)-1 and B(IV)-2,and the propyl chain of the TPAs.Amorphous B(IV)-1 species exhibit a strong preference for proximity to the nitrogen cation center of the OSDAs,while framework B(IV)-2 species engage with components situated at greater distances from the cation center.Moreover,13C-{11B}symmetry-based resonance-echo saturation-pulse double-resonance(S-RESPDOR)experiments revealed that framework boron species preferentially occupy the straight channels of the MFI structure,as evidenced by their interaction with specificmethyl groups on the TPAmolecules.This observation provides valuable insights into the crystallization mechanism of boron-based zeolites,suggesting that the conformation and orientation of the OSDA molecules play a critical role in determining the location of boron atoms within the zeolite framework.展开更多
To reduce greenhouse gas emission from oil and gas production,it is essential to better convert methane to useful chemicals(rather) than to flare it.Conversion of methane to liquid oxygenates(mainly methanol) has attr...To reduce greenhouse gas emission from oil and gas production,it is essential to better convert methane to useful chemicals(rather) than to flare it.Conversion of methane to liquid oxygenates(mainly methanol) has attracted extensive attention and countless efforts have been made;however,running this reaction in a green,efficient,and practical way has remained elusive.The novel catalyst and oxidants play a critical role in activating methane and converting it to oxygenates(methanol).In this review,the work of commonly used oxidants for methane partial oxidation have been summarized,in which,earth abundant oxidants,O;and H;O are promising.Moreover,H;or CO can activate O;to produce H;O;that catalyzes methane partial oxidation more efficiently and selectively than O;or H;O.Therefore,the work of using reducing agent,such as CO and H;have been reviewed,focusing on rational catalyst design that features multifunction(H;O;production and CH;activation).The novel catalyst design has advanced this reaction towards practicality with green oxidants and H;using zeolites-based catalyst.Environmentally friendly zeolite preparation methods and novel two-dimensional(2 D) zeolites that can reduce waste,improve synthesis and catalytical performance substantially are also reviewed in this work to provide insights for a more comprehensive approach to meet the environment protection needs.展开更多
The size and shape of rice grains influence their yield and commercial value.We investigated the role of OsDA1,a rice homolog of the Arabidopsis DA1 gene,in regulating grain size and shape.OsDA1 was highly expressed i...The size and shape of rice grains influence their yield and commercial value.We investigated the role of OsDA1,a rice homolog of the Arabidopsis DA1 gene,in regulating grain size and shape.OsDA1 was highly expressed in young spikelets and glumes.Its overexpression led to enlarged seeds with increased width and decreased length/width ratio(LWR)and knocking out OsDA1 reduced grain width and increased grain length and LWR.A R310K point mutation in the DA1-like domain is a potential target for breeding for increased grain width and length.OsDA1 interacted with TCP gene-family proteins to regulate grain size and shape.Our findings deepen our understanding of the molecular mechanisms underlying grain size regulation and provide useful information for improving grain yield.展开更多
The organic structure-directing agent(OSDA)-free synthesis of MCM-49 is strongly desired because OSDA makes synthesis cost expensive and environment unfriendly.In this work,an efficient,eco-friendly and simple route t...The organic structure-directing agent(OSDA)-free synthesis of MCM-49 is strongly desired because OSDA makes synthesis cost expensive and environment unfriendly.In this work,an efficient,eco-friendly and simple route to synthesize MCM-49 zeolite is developed,via seed-assistance,without deliberately adding OSDA,with ultraphonic aging treatment.For comparison,the effect of microwave aging,mechanical stirring aging and without any aging processes on the synthesis is investigated.Due to the acoustic cavitation,the ultraphonic aging treatment shows superiority over the others.Ultraphonic aging not only keeps the MCM-49 seed integrity but also promotes both the silica species and aluminum species to the solid phase,which is beneficial for the growth of MCM-49 and the suppression of MOR formation in the absence of OSDA.^(27)Al MAS NMR data show that the seed-assisted MCM-49 almost has no extra-framework aluminum,but dealumination will happen upon ammonium exchange.^(23)Na MAS NMR results demonstrate that the interaction between Na ions and framework of the seed-assisted MWW product is strengthened after calcination,which makes the exchange of Na species difficult.Alternatively,ammonium exchange upon the as-made sample is an effective method to remove Na species,which improves the micropore volume,external surface area,and acid amount of the seed-assisted MCM-49.展开更多
Partially removing the framework Al atoms from low-silica aluminosilicates is an old but still challenging problem,because a high framework Al content generally induces lower acid strength and fast deactivation.An ina...Partially removing the framework Al atoms from low-silica aluminosilicates is an old but still challenging problem,because a high framework Al content generally induces lower acid strength and fast deactivation.An inappropriate dealumination method may cause structural collapse.The organic structuredirecting agent(OSDA)-free Beta zeolite is expected to serve as a green solid acid catalyst,but decreasing the Al content before being used as a catalyst is needed to enhance the stability and acid strength.Al2(SO4)3 was used to extract effectively the framework Al species from Al-rich OSDA-free Beta(Si/Al=4.3)under mild conditions,forming a natroalunite phase.The natroalunite phase was then selectively washed away with diluted NaOH solution,resulting in dealuminated zeolite(DeAl Beta)with a pure^(*)BEA phase and higher Si/Al ratios of 7.6-12.The dealuminated Beta zeolites were revealed to possess abundant mesopores while maintaining high crystallinity.The decrease of the total acid amount in DeAl Beta zeolites was accompanied by the enhancement of acid strength,resulting in higher selectivity of deeper cracking products and lower deactivation rate in the 1,3,5-triisopropylbenzene cracking reaction.The DeAl Beta also showed a high catalytic activity comparable to commercial nanosized Beta in the liquidphase Friedel-Crafts acylation,which was much higher than the parent Al-rich Beta.This study would provide a promising method for developing useful solid acid catalysts by the combination of OSDA-free synthesis and the eco-efficient dealumination process.展开更多
Direct one-pot synthesis of delaminated layered zeolitic materials aims to create two-dimensionally confined catalysts for reactions involving sterically bulky reactants,which are too large to benefit from conventiona...Direct one-pot synthesis of delaminated layered zeolitic materials aims to create two-dimensionally confined catalysts for reactions involving sterically bulky reactants,which are too large to benefit from conventional three-dimensional confinement in micropores.As a prototypical system,several efforts have focused on the development of post-synthetic approaches for delamination of silica-rich MWW layered zeolite precursors.展开更多
Zeolites are widely recognised as effective adsorbents for the removal of organic pollutants from aqueous sources.However,their intrinsic powder form makes their application restricted by the arduous filtrationrecover...Zeolites are widely recognised as effective adsorbents for the removal of organic pollutants from aqueous sources.However,their intrinsic powder form makes their application restricted by the arduous filtrationrecovery process and their decreased activity due to aggregation.Herein,we report the organic structure directing agent(OSDA)free and binder-free preparation of ZSM-5@silica beads for organic pollutant sequestration exemplified by the aniline removal.All silica beads were prepared by employing ion exchange resin beads as a macro-template and further used to prepare a ZSM-5@silica composite.First,anion exchange resin beads were charged with silica by ion exchange.Second,the anion exchange resin was eliminated by high temperature combustion leaving behind an all-silica replica.The all-silica replica was partially transformed into ZSM-5 by hydrothermal treatment.ZSM-5 was synthesized from the OSDA-free system,thus avoiding high temperature calcination of the composite.The effect of the crystallization temperature(120,150,and 170℃)on the formation of ZSM-5 was studied.The physicochemical properties of the obtained beads were determined using different characterization methods such as powder X-ray diffraction(XRD),scanning-electron microscopy(SEM),N_(2)adsorption–desorption isotherms,and thermogravimetry(TG).The ZSM-5@silica composite demonstrated a remarkable capacity,outpacing most silica-based adsorbents and modified zeolitic materials,re-usability and retained spherical shape.The binder-free zeolite shaping technology offers a green and straightforward method for preparing zeolite-based adsorbents for the removal of organic pollutants from waste water.展开更多
基金supported by the National Energy R&D Center of Petroleum Refining Technology(RIPP,SINOPEC),the National Natural Science Foundation of China(Grants 22161132028,22172177,22225205,22372191 and 22372178)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0540000)+2 种基金the International Partnership Program of the Chinese Academy of Sciences(314GJH2022022FN)Natural Science Foundation of Hubei Province(2021CFA021)Hubei International Scientific and Technological Cooperation Program(2024EHA043)and Base(SH2303).
文摘Organic structure directingagents(OSDAs),suchas tetrapropylammonium(TPA)cations,serve as crucial templates for the formation of zeolite frameworks.These organic molecules interact with inorganic species,guiding the assembly of the zeolite structure.In this study,we inves-tigate the complex interplay between boron species and TPA cations during the crystallization of[B,Al]-ZSM-5 zeolites.Two-dimensional(2D)11B-{1H}cross-polarization heteronuclear correlation(CP-HECTOR)NMRexperiments elucidate distinct interactions between two boron species,B(IV)-1 and B(IV)-2,and the propyl chain of the TPAs.Amorphous B(IV)-1 species exhibit a strong preference for proximity to the nitrogen cation center of the OSDAs,while framework B(IV)-2 species engage with components situated at greater distances from the cation center.Moreover,13C-{11B}symmetry-based resonance-echo saturation-pulse double-resonance(S-RESPDOR)experiments revealed that framework boron species preferentially occupy the straight channels of the MFI structure,as evidenced by their interaction with specificmethyl groups on the TPAmolecules.This observation provides valuable insights into the crystallization mechanism of boron-based zeolites,suggesting that the conformation and orientation of the OSDA molecules play a critical role in determining the location of boron atoms within the zeolite framework.
文摘To reduce greenhouse gas emission from oil and gas production,it is essential to better convert methane to useful chemicals(rather) than to flare it.Conversion of methane to liquid oxygenates(mainly methanol) has attracted extensive attention and countless efforts have been made;however,running this reaction in a green,efficient,and practical way has remained elusive.The novel catalyst and oxidants play a critical role in activating methane and converting it to oxygenates(methanol).In this review,the work of commonly used oxidants for methane partial oxidation have been summarized,in which,earth abundant oxidants,O;and H;O are promising.Moreover,H;or CO can activate O;to produce H;O;that catalyzes methane partial oxidation more efficiently and selectively than O;or H;O.Therefore,the work of using reducing agent,such as CO and H;have been reviewed,focusing on rational catalyst design that features multifunction(H;O;production and CH;activation).The novel catalyst design has advanced this reaction towards practicality with green oxidants and H;using zeolites-based catalyst.Environmentally friendly zeolite preparation methods and novel two-dimensional(2 D) zeolites that can reduce waste,improve synthesis and catalytical performance substantially are also reviewed in this work to provide insights for a more comprehensive approach to meet the environment protection needs.
基金This work is supported in part by the National Transgenic Science and Technology Program(2016ZX08010-002)National Natural Science Foundation of China(157101834)Agricultural Science and Technology Innovation Program of CAAS.
文摘The size and shape of rice grains influence their yield and commercial value.We investigated the role of OsDA1,a rice homolog of the Arabidopsis DA1 gene,in regulating grain size and shape.OsDA1 was highly expressed in young spikelets and glumes.Its overexpression led to enlarged seeds with increased width and decreased length/width ratio(LWR)and knocking out OsDA1 reduced grain width and increased grain length and LWR.A R310K point mutation in the DA1-like domain is a potential target for breeding for increased grain width and length.OsDA1 interacted with TCP gene-family proteins to regulate grain size and shape.Our findings deepen our understanding of the molecular mechanisms underlying grain size regulation and provide useful information for improving grain yield.
基金supported by the National Natural Science Foundation of China(U20A20120)Dalian Science and Technology Innovation Fund Project(2019J12GX027)+2 种基金LiaoNing Revitalization Talents Program(XLYC1901006 and XLYC1908010)Dalian Engineering Research Center for Key Aromatic CompoundsSTS Network Initiative of the CAS(KFJ-STS-QYZD-2021-17-001).
文摘The organic structure-directing agent(OSDA)-free synthesis of MCM-49 is strongly desired because OSDA makes synthesis cost expensive and environment unfriendly.In this work,an efficient,eco-friendly and simple route to synthesize MCM-49 zeolite is developed,via seed-assistance,without deliberately adding OSDA,with ultraphonic aging treatment.For comparison,the effect of microwave aging,mechanical stirring aging and without any aging processes on the synthesis is investigated.Due to the acoustic cavitation,the ultraphonic aging treatment shows superiority over the others.Ultraphonic aging not only keeps the MCM-49 seed integrity but also promotes both the silica species and aluminum species to the solid phase,which is beneficial for the growth of MCM-49 and the suppression of MOR formation in the absence of OSDA.^(27)Al MAS NMR data show that the seed-assisted MCM-49 almost has no extra-framework aluminum,but dealumination will happen upon ammonium exchange.^(23)Na MAS NMR results demonstrate that the interaction between Na ions and framework of the seed-assisted MWW product is strengthened after calcination,which makes the exchange of Na species difficult.Alternatively,ammonium exchange upon the as-made sample is an effective method to remove Na species,which improves the micropore volume,external surface area,and acid amount of the seed-assisted MCM-49.
基金supported by the National Natural Science Foundation of China(Grant No.21872052,21533002,and 21972044)the Ministry of Science and Technology of the People’s Republic of China(2016YFA0202804)the Fundamental Research Funds for the Central Universities.
文摘Partially removing the framework Al atoms from low-silica aluminosilicates is an old but still challenging problem,because a high framework Al content generally induces lower acid strength and fast deactivation.An inappropriate dealumination method may cause structural collapse.The organic structuredirecting agent(OSDA)-free Beta zeolite is expected to serve as a green solid acid catalyst,but decreasing the Al content before being used as a catalyst is needed to enhance the stability and acid strength.Al2(SO4)3 was used to extract effectively the framework Al species from Al-rich OSDA-free Beta(Si/Al=4.3)under mild conditions,forming a natroalunite phase.The natroalunite phase was then selectively washed away with diluted NaOH solution,resulting in dealuminated zeolite(DeAl Beta)with a pure^(*)BEA phase and higher Si/Al ratios of 7.6-12.The dealuminated Beta zeolites were revealed to possess abundant mesopores while maintaining high crystallinity.The decrease of the total acid amount in DeAl Beta zeolites was accompanied by the enhancement of acid strength,resulting in higher selectivity of deeper cracking products and lower deactivation rate in the 1,3,5-triisopropylbenzene cracking reaction.The DeAl Beta also showed a high catalytic activity comparable to commercial nanosized Beta in the liquidphase Friedel-Crafts acylation,which was much higher than the parent Al-rich Beta.This study would provide a promising method for developing useful solid acid catalysts by the combination of OSDA-free synthesis and the eco-efficient dealumination process.
基金Department of Energy,Office of Science,Basic Energy Sciences(DE-FG02-05ER15696)for supporting the catalysis and materials characterization aspects of this workthe Management and Transfer of Hydrogen via Catalysis Program funded by Chevron Corporation for supporting the materials synthesis work in this manuscript.
文摘Direct one-pot synthesis of delaminated layered zeolitic materials aims to create two-dimensionally confined catalysts for reactions involving sterically bulky reactants,which are too large to benefit from conventional three-dimensional confinement in micropores.As a prototypical system,several efforts have focused on the development of post-synthetic approaches for delamination of silica-rich MWW layered zeolite precursors.
基金Q.F.and V.V.thank the National Natural Science Foundation of China(21571079,21621001,21390394,21571076 and 21571078)for their financial supportThis study was partially supported by the Sino-French International Associated Laboratory“Zeolites”.
文摘Zeolites are widely recognised as effective adsorbents for the removal of organic pollutants from aqueous sources.However,their intrinsic powder form makes their application restricted by the arduous filtrationrecovery process and their decreased activity due to aggregation.Herein,we report the organic structure directing agent(OSDA)free and binder-free preparation of ZSM-5@silica beads for organic pollutant sequestration exemplified by the aniline removal.All silica beads were prepared by employing ion exchange resin beads as a macro-template and further used to prepare a ZSM-5@silica composite.First,anion exchange resin beads were charged with silica by ion exchange.Second,the anion exchange resin was eliminated by high temperature combustion leaving behind an all-silica replica.The all-silica replica was partially transformed into ZSM-5 by hydrothermal treatment.ZSM-5 was synthesized from the OSDA-free system,thus avoiding high temperature calcination of the composite.The effect of the crystallization temperature(120,150,and 170℃)on the formation of ZSM-5 was studied.The physicochemical properties of the obtained beads were determined using different characterization methods such as powder X-ray diffraction(XRD),scanning-electron microscopy(SEM),N_(2)adsorption–desorption isotherms,and thermogravimetry(TG).The ZSM-5@silica composite demonstrated a remarkable capacity,outpacing most silica-based adsorbents and modified zeolitic materials,re-usability and retained spherical shape.The binder-free zeolite shaping technology offers a green and straightforward method for preparing zeolite-based adsorbents for the removal of organic pollutants from waste water.
