Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to ...Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.展开更多
We report results from computational modeling of the relative stability of germanosilicate SCM-15 structure due to different distribution of germanium heteroatoms in the double four-member rings(D4Rs)of the framework ...We report results from computational modeling of the relative stability of germanosilicate SCM-15 structure due to different distribution of germanium heteroatoms in the double four-member rings(D4Rs)of the framework and the orientation of the structure directing agent(SDA)molecules in the as-synthesized zeolite.The calculated relative energies of the bare zeolite framework suggest that structures with germanium ions clustered in the same D4Rs,e.g.,with large number of Ge–O-Ge contacts,are the most stable.The simulations of various orientations of the SDA in the pores of the germanosilicate zeolite show different stability order-the most stable models are the structures with germanium spread among all D4Rs.Thus,for SCM-15 the stabilization due to the presence of the SDA and their orientation,is thermodynamic factor directing both the formation of specific framework type and Ge distribution in the framework during the synthesis.The relative stability of bare structures with different germanium distribution is of minor importance.This differs from SCM-14 germanosilicate,reported earlier,for which the stability order is preserved in presence of SDA.Thus,even for zeolites with the same chemical composition and SDA,the characteristics of their framework lead to different energetic preference for germanium distribution.展开更多
以工业级水玻璃为硅源,在无模板剂、无导向剂、无添加剂的条件下,成功地合成了粒径小于100nm的NaY分子筛,并采用XRD、FT-IR、SEM、粒度分析、N2吸附-脱附、ICP、29Si和27 Al NMR等手段对其进行表征。考察了合成体系中n(Na_2O)/n(Al_2O_3...以工业级水玻璃为硅源,在无模板剂、无导向剂、无添加剂的条件下,成功地合成了粒径小于100nm的NaY分子筛,并采用XRD、FT-IR、SEM、粒度分析、N2吸附-脱附、ICP、29Si和27 Al NMR等手段对其进行表征。考察了合成体系中n(Na_2O)/n(Al_2O_3)、n(H2O)/n(Al_2O_3)及初始凝胶陈化温度与陈化时间对NaY分子筛晶粒大小的影响,并与常规工业NaY进行比较。结果表明,增大n(Na_2O)/n(Al_2O_3),有利于减小NaY分子筛的晶粒尺寸,但同时也降低了其相对结晶度,当n(Na_2O)/n(Al_2O_3)大于17时,导致NaY分子筛向P型分子筛转变;降低n(H_2O)/n(Al_2O_3),有利于生成小晶粒NaY分子筛,但当n(H2O)/n(Al_2O_3)低于240时,就会出现P型杂晶。NaY分子筛的平均粒径随着初始凝胶陈化温度的升高而减小,但当陈化温度达到70℃时,得到P型分子筛产物;随着初始凝胶陈化时间的延长,NaY分子筛的粒径逐渐变小,陈化时间长于5h时,就会出现P型杂晶。在n(Na_2O)/n(Al_2O_3)为16、n(H_2O)/n(Al_2O_3)为360、65℃陈化4h的优化合成条件下,合成了平均粒径在80nm左右且粒度分布较窄的NaY分子筛,其骨架nSi/nAl=2.18。展开更多
Zeolites are crystalline porous materials that are used in the chemical industry for adsorption, separation and catalytic reactions. Chiral zeolites have shown promise in enantioselective adsorption and catalytic orga...Zeolites are crystalline porous materials that are used in the chemical industry for adsorption, separation and catalytic reactions. Chiral zeolites have shown promise in enantioselective adsorption and catalytic organic reactions, attracting significant research interest. Recent advances have been made in the rational design, computational prediction and hydrothermal synthesis of using chiral organic structure-directing agents. Additionally, newly developed electron microscopic techniques have been utilized to analyze the structure and determine absolute configuration. The following review aims to provide an overview of the development history of chiral zeolites, examine several prominent chiral zeolite structures discovered so far, discuss the recent progress in characterization methods and explore their potential applications.展开更多
In this contribution,we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate*BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time.*BEA zeolites,a...In this contribution,we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate*BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time.*BEA zeolites,at variance with any other aluminosilicate zeolites,can serve as heterogeneous seeds for the growth of IWR zeolites and play a cooperative structure-directing role.The crystallization process was investigated using multiple techniques to characterize a series of solid products obtained with various crystallization times.The experiments clearly showed the dissolution of the*BEA zeolite and of an intermediate CDO-type structure.A plausible mechanism for the novel cooperative synthesis has been proposed.The crystallization of the IWR zeolite involves several steps,among which the crucial one is believed to be the reassembly of the building units produced from the decomposition of*BEA zeolite seeds,induced by choline molecules.Having similar structure and common building units(four-,five-,and six-membered rings)with the IWR zeolite,the*BEA zeolite is capable of promoting the reassembly of the building units and can thus play a cooperative structure-directing role.By highlighting the cooperative structure-directing effect of organic molecules and heterogeneous seeds,this study opens up new perspectives for the synthesis of target zeolites that are difficult to prepare by traditional methods.This new synthetic route is also expected to shed light on the discovery of novel zeolites.展开更多
Novel flowerlike Cu20 micro-nanocrystals were prepared by a greener reductive reaction of cupric acetate monohydrate with ethylene glycol in aqueous solutions of [C8mim]X （X = CI-, Br-, BF4-, PFr-） and [C,,mim][BF4]...Novel flowerlike Cu20 micro-nanocrystals were prepared by a greener reductive reaction of cupric acetate monohydrate with ethylene glycol in aqueous solutions of [C8mim]X （X = CI-, Br-, BF4-, PFr-） and [C,,mim][BF4] （n = 4, 6, 8）. The obtained mi- crostructures of Cu2O were characterized by Scanning Electron Microscopy （SEM）, X-ray diffraction （XRD） and Fourier Transform Infrared （FT-IR）. The effects of cations, anions and concentration of the ionic liquids on the morphology of Cu20 were examined in some details. The results suggest that the formation of flowerlike Cu20 was governed by a [Csmim][BF4] controlled reductive reaction mechanism. As one of their applications, the Cu20 nanoparticles were used for the photocatalytic degradation of methylene blue in aqueous solution, and high photocatalytic activity was observed.展开更多
Zeolites are of great industrial relevance as catalysts,adsorbents,and ion-exchangers and typically synthesized under hydrothermal conditions.Rational regulation of their crystallization process is of great significan...Zeolites are of great industrial relevance as catalysts,adsorbents,and ion-exchangers and typically synthesized under hydrothermal conditions.Rational regulation of their crystallization process is of great significance for zeolite production.In this work,we systematically investigate the role of anions in tuning zeolite crystallization via anion introduction including SO_(4)^(2−),F^(−),Cl^(−),Br^(−),I^(−),and SCN^(−) in the sodium form into the SiO2-TPAOH-H2O[tetrapropylammonium hydroxide(TPAOH)]synthetic system of silicalite-1 zeolite.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.21802136)~~
文摘Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.
文摘We report results from computational modeling of the relative stability of germanosilicate SCM-15 structure due to different distribution of germanium heteroatoms in the double four-member rings(D4Rs)of the framework and the orientation of the structure directing agent(SDA)molecules in the as-synthesized zeolite.The calculated relative energies of the bare zeolite framework suggest that structures with germanium ions clustered in the same D4Rs,e.g.,with large number of Ge–O-Ge contacts,are the most stable.The simulations of various orientations of the SDA in the pores of the germanosilicate zeolite show different stability order-the most stable models are the structures with germanium spread among all D4Rs.Thus,for SCM-15 the stabilization due to the presence of the SDA and their orientation,is thermodynamic factor directing both the formation of specific framework type and Ge distribution in the framework during the synthesis.The relative stability of bare structures with different germanium distribution is of minor importance.This differs from SCM-14 germanosilicate,reported earlier,for which the stability order is preserved in presence of SDA.Thus,even for zeolites with the same chemical composition and SDA,the characteristics of their framework lead to different energetic preference for germanium distribution.
文摘以工业级水玻璃为硅源,在无模板剂、无导向剂、无添加剂的条件下,成功地合成了粒径小于100nm的NaY分子筛,并采用XRD、FT-IR、SEM、粒度分析、N2吸附-脱附、ICP、29Si和27 Al NMR等手段对其进行表征。考察了合成体系中n(Na_2O)/n(Al_2O_3)、n(H2O)/n(Al_2O_3)及初始凝胶陈化温度与陈化时间对NaY分子筛晶粒大小的影响,并与常规工业NaY进行比较。结果表明,增大n(Na_2O)/n(Al_2O_3),有利于减小NaY分子筛的晶粒尺寸,但同时也降低了其相对结晶度,当n(Na_2O)/n(Al_2O_3)大于17时,导致NaY分子筛向P型分子筛转变;降低n(H_2O)/n(Al_2O_3),有利于生成小晶粒NaY分子筛,但当n(H2O)/n(Al_2O_3)低于240时,就会出现P型杂晶。NaY分子筛的平均粒径随着初始凝胶陈化温度的升高而减小,但当陈化温度达到70℃时,得到P型分子筛产物;随着初始凝胶陈化时间的延长,NaY分子筛的粒径逐渐变小,陈化时间长于5h时,就会出现P型杂晶。在n(Na_2O)/n(Al_2O_3)为16、n(H_2O)/n(Al_2O_3)为360、65℃陈化4h的优化合成条件下,合成了平均粒径在80nm左右且粒度分布较窄的NaY分子筛,其骨架nSi/nAl=2.18。
基金Financial support from Institute of Chemistry, Chinese Academy of Sciences。
文摘Zeolites are crystalline porous materials that are used in the chemical industry for adsorption, separation and catalytic reactions. Chiral zeolites have shown promise in enantioselective adsorption and catalytic organic reactions, attracting significant research interest. Recent advances have been made in the rational design, computational prediction and hydrothermal synthesis of using chiral organic structure-directing agents. Additionally, newly developed electron microscopic techniques have been utilized to analyze the structure and determine absolute configuration. The following review aims to provide an overview of the development history of chiral zeolites, examine several prominent chiral zeolite structures discovered so far, discuss the recent progress in characterization methods and explore their potential applications.
基金supported by the National Key R&D Program of China(2017YFB0702800)National Natural Science Foundation of China(21802168,21503280,21603277)China Petrochemical Corporation(Sinopec Group)~~
文摘In this contribution,we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate*BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time.*BEA zeolites,at variance with any other aluminosilicate zeolites,can serve as heterogeneous seeds for the growth of IWR zeolites and play a cooperative structure-directing role.The crystallization process was investigated using multiple techniques to characterize a series of solid products obtained with various crystallization times.The experiments clearly showed the dissolution of the*BEA zeolite and of an intermediate CDO-type structure.A plausible mechanism for the novel cooperative synthesis has been proposed.The crystallization of the IWR zeolite involves several steps,among which the crucial one is believed to be the reassembly of the building units produced from the decomposition of*BEA zeolite seeds,induced by choline molecules.Having similar structure and common building units(four-,five-,and six-membered rings)with the IWR zeolite,the*BEA zeolite is capable of promoting the reassembly of the building units and can thus play a cooperative structure-directing role.By highlighting the cooperative structure-directing effect of organic molecules and heterogeneous seeds,this study opens up new perspectives for the synthesis of target zeolites that are difficult to prepare by traditional methods.This new synthetic route is also expected to shed light on the discovery of novel zeolites.
基金supported financially by the National Natural Science Foundation of China (21003039)the Innovation Scientists and Technicians Troop Construction Projects of Henan Province (092101510300)the Program for Science & Technology Innovation Talents in Universities of Henan Province (2009HASTIT005)
文摘Novel flowerlike Cu20 micro-nanocrystals were prepared by a greener reductive reaction of cupric acetate monohydrate with ethylene glycol in aqueous solutions of [C8mim]X （X = CI-, Br-, BF4-, PFr-） and [C,,mim][BF4] （n = 4, 6, 8）. The obtained mi- crostructures of Cu2O were characterized by Scanning Electron Microscopy （SEM）, X-ray diffraction （XRD） and Fourier Transform Infrared （FT-IR）. The effects of cations, anions and concentration of the ionic liquids on the morphology of Cu20 were examined in some details. The results suggest that the formation of flowerlike Cu20 was governed by a [Csmim][BF4] controlled reductive reaction mechanism. As one of their applications, the Cu20 nanoparticles were used for the photocatalytic degradation of methylene blue in aqueous solution, and high photocatalytic activity was observed.
基金National Natural Science Foundation of China(nos.21621001,21835002,U1967215,and 21920102005)the 111 Project(no.B17020)for supporting this work.
文摘Zeolites are of great industrial relevance as catalysts,adsorbents,and ion-exchangers and typically synthesized under hydrothermal conditions.Rational regulation of their crystallization process is of great significance for zeolite production.In this work,we systematically investigate the role of anions in tuning zeolite crystallization via anion introduction including SO_(4)^(2−),F^(−),Cl^(−),Br^(−),I^(−),and SCN^(−) in the sodium form into the SiO2-TPAOH-H2O[tetrapropylammonium hydroxide(TPAOH)]synthetic system of silicalite-1 zeolite.
