Ge-containing Lewis acidic zeolites are typically synthesized using a conventional hydrothermal strategy from amorphous silica sources,through a long time-and energy-consuming approach limiting their wide applications...Ge-containing Lewis acidic zeolites are typically synthesized using a conventional hydrothermal strategy from amorphous silica sources,through a long time-and energy-consuming approach limiting their wide applications.This study reports a rapid synthesis strategy for a series of IWV aluminogermanosilicate zeolites(T-x-Al)with a wide range of Si/Ge molar ratios(5–15)by interzeolite transformation of dealuminated FAU(DA-FAU).Notably,Ge-rich IWV could be obtained with crystallization time as short as one day by the equimolecular Si/Ge ratio gel.The effect of synthetic parameters was investigated and the obtained T-x-Al samples were characterized by XRD,SEM,EDS,ICP,^(29)Si and^(27)Al MAS NMR,FTIR,and N_(2)physisorption analyses.Compared with a previously reported IWV germanosilicate(H-3),T-x-Al displayed a better catalytic activity in Baeyer-Villiger(BV)oxidation,attributed to the presence of the active framework Ge sites with the assistance of the extraframework Al species.The cyclic catalysis tests revealed that the presence of framework Al species contributed to the stability of the T-x-Al.Specifically,T-x-Al,with 14-membered ring(MR)supercages,outperformed the typical 12-MR Sn-beta catalyst in the BV oxidation of large ketone-like 2-admantanone,indicating a promising potential application in the macromolecular catalytic process.展开更多
In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Ka...In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Karsten's model at Kolkata, a tropical location in the Indian region. Cloud liquid water contents (LWC) are obtained from these profiles which show a prominent seasonal variation. The monsoon months exhibit much higher values of LWC than in other months. However Salonen's model yields higher LWC values than that obtained with Karsten's model. The variation of daily total rainfall with LWC shows a positive relationship indicating the role of LWC in controlling the rainfall. Also the variation pattern of LWC with integrated water vapor (IWV) content of the atmosphere indicates that a threshold value of water vapor is required for cloud to form and once cloud is formed LWC increases with IWV.展开更多
Modulation of zeolite porosity,including the size and type of channel and cage,is essential for catalysis and separation.Although zeolites with a variety of porous systems have been synthesized by hydrothermal or post...Modulation of zeolite porosity,including the size and type of channel and cage,is essential for catalysis and separation.Although zeolites with a variety of porous systems have been synthesized by hydrothermal or post-synthetic routes,there is still a lack of rational control of zeolite porosity in the range of large to medium pore/cage.Herein,based on the rational structure building,the structure similarity between IWV topology with large-pore opening and supercage and NES topology with medium-pore opening and medium cage is discovered.Based on the guidance of structure building,two IWV-derived daughter zeolites with different framework compositions,(Si,Ge)-ECNU-31 and(Si,Ge,Al)-ECNU-31,are hydrothermally prepared with built-in structural weakness due to the presence of a large amount of framework Ge atoms,which are utilized to prepare ECNU-32 zeolite with NES topology through subsequent post-synthetic treatment under controlled condition.It is demonstrated that the parent IWV zeolite with only Ge and Si as framework atoms is benefit in post-treatment to obtain a highly crystalline NES zeolite.In contrast,the co-existence of framework Al atoms in(Si,Ge,Al)-ECNU-31 zeolite enhances its hydrothermal stability in water.However,the treatment with acid and amine solutions causes the partial collapse of zeolite structure.Our results demonstrate that rational selection of the framework composition and post-synthetic parameters are crucial for the transformation of large-pore zeolite to medium-pore zeolite.展开更多
基金supported by the National Natural Science Foundation of China(22302116)the Natural Science Foundation of Shanxi Province(202203021212412)。
文摘Ge-containing Lewis acidic zeolites are typically synthesized using a conventional hydrothermal strategy from amorphous silica sources,through a long time-and energy-consuming approach limiting their wide applications.This study reports a rapid synthesis strategy for a series of IWV aluminogermanosilicate zeolites(T-x-Al)with a wide range of Si/Ge molar ratios(5–15)by interzeolite transformation of dealuminated FAU(DA-FAU).Notably,Ge-rich IWV could be obtained with crystallization time as short as one day by the equimolecular Si/Ge ratio gel.The effect of synthetic parameters was investigated and the obtained T-x-Al samples were characterized by XRD,SEM,EDS,ICP,^(29)Si and^(27)Al MAS NMR,FTIR,and N_(2)physisorption analyses.Compared with a previously reported IWV germanosilicate(H-3),T-x-Al displayed a better catalytic activity in Baeyer-Villiger(BV)oxidation,attributed to the presence of the active framework Ge sites with the assistance of the extraframework Al species.The cyclic catalysis tests revealed that the presence of framework Al species contributed to the stability of the T-x-Al.Specifically,T-x-Al,with 14-membered ring(MR)supercages,outperformed the typical 12-MR Sn-beta catalyst in the BV oxidation of large ketone-like 2-admantanone,indicating a promising potential application in the macromolecular catalytic process.
文摘In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Karsten's model at Kolkata, a tropical location in the Indian region. Cloud liquid water contents (LWC) are obtained from these profiles which show a prominent seasonal variation. The monsoon months exhibit much higher values of LWC than in other months. However Salonen's model yields higher LWC values than that obtained with Karsten's model. The variation of daily total rainfall with LWC shows a positive relationship indicating the role of LWC in controlling the rainfall. Also the variation pattern of LWC with integrated water vapor (IWV) content of the atmosphere indicates that a threshold value of water vapor is required for cloud to form and once cloud is formed LWC increases with IWV.
基金supported by the National Natural Science Foundation of China(Nos.22272079,22302116)the National Key R&D Program of China(Nos.2023YFB3810602,2021YFA1501401)the Natural Science Foundation of Shanxi Province(No.202203021212412).
文摘Modulation of zeolite porosity,including the size and type of channel and cage,is essential for catalysis and separation.Although zeolites with a variety of porous systems have been synthesized by hydrothermal or post-synthetic routes,there is still a lack of rational control of zeolite porosity in the range of large to medium pore/cage.Herein,based on the rational structure building,the structure similarity between IWV topology with large-pore opening and supercage and NES topology with medium-pore opening and medium cage is discovered.Based on the guidance of structure building,two IWV-derived daughter zeolites with different framework compositions,(Si,Ge)-ECNU-31 and(Si,Ge,Al)-ECNU-31,are hydrothermally prepared with built-in structural weakness due to the presence of a large amount of framework Ge atoms,which are utilized to prepare ECNU-32 zeolite with NES topology through subsequent post-synthetic treatment under controlled condition.It is demonstrated that the parent IWV zeolite with only Ge and Si as framework atoms is benefit in post-treatment to obtain a highly crystalline NES zeolite.In contrast,the co-existence of framework Al atoms in(Si,Ge,Al)-ECNU-31 zeolite enhances its hydrothermal stability in water.However,the treatment with acid and amine solutions causes the partial collapse of zeolite structure.Our results demonstrate that rational selection of the framework composition and post-synthetic parameters are crucial for the transformation of large-pore zeolite to medium-pore zeolite.
