4A Zeolite has been prepared from Kaolin under low-temperature hydrothermal conditions. The analysis results on the concentration changes of NaOH, SiO2 and Al2O3 in liquid phases as well as the texture, morphology and...4A Zeolite has been prepared from Kaolin under low-temperature hydrothermal conditions. The analysis results on the concentration changes of NaOH, SiO2 and Al2O3 in liquid phases as well as the texture, morphology and structure changes of solid phases show that the crystallization process of 4A zeolite roughly comprises three periods: induction of crystal nucleus, crystal growth and steady state transformation.展开更多
The synthesis of ferrierite(FER)zeolite using piperidine as an organic structure‐directing agent was investigated.X‐ray diffraction,X‐ray fluorescence,N2‐adsorption,and scanning electron microscopy were used to ch...The synthesis of ferrierite(FER)zeolite using piperidine as an organic structure‐directing agent was investigated.X‐ray diffraction,X‐ray fluorescence,N2‐adsorption,and scanning electron microscopy were used to characterize the crystal phases,textural properties,and particle morphologies of the zeolite samples.The crystallization behavior of the FER zeolite was found to be directly related to crystallization temperature.At150?C,pure FER phase was observed throughout crystallization.At160–170?C,MWW phase appeared first and gradually transformed into FER phase over time,indicating that the FER phase was thermodynamically favored.In the piperidine‐Na2O‐H2O synthetic system,alkalinity proved to be the crucial factor determining the size and textural properties of FER zeolite.Furthermore,the obtained FER samples exhibited good catalytic performance in the skeletal isomerization of1‐butene.展开更多
Solid-state crystallization process and mechanism of B-Al-ZSM-5 zeolite from a dry gel of B2O3. A12O3 ? SiO2 in the mixture of ethylamine and water vapour were studied by11B,27Al,29Si,13C MAS NMR, XRD and IR. The extr...Solid-state crystallization process and mechanism of B-Al-ZSM-5 zeolite from a dry gel of B2O3. A12O3 ? SiO2 in the mixture of ethylamine and water vapour were studied by11B,27Al,29Si,13C MAS NMR, XRD and IR. The extranetwork trigonal BO3 units in the gel play an important role in the process of crystallization. The change of chemical environment around Al atoms is complicated in the process of crystallization. Octahedral Al-O groups existing in the intermediate products do not appear in both the initial gel and final product. Silicon is mainly present as hydroxyl compounds, and the extrastructural Si-O groups detected in the process of crystallization disappear after complete crystallization. Ethylamine plays the role of both template and reactant. It acts with the boron-, aluminum-, and silicon-hydroxyls through hydrogen bonding and promotes the crystallization process. The relative crystallinity of the final & A1-ZSM-5 product is about 93% as measured with11B MAS NMR and IR.展开更多
文摘4A Zeolite has been prepared from Kaolin under low-temperature hydrothermal conditions. The analysis results on the concentration changes of NaOH, SiO2 and Al2O3 in liquid phases as well as the texture, morphology and structure changes of solid phases show that the crystallization process of 4A zeolite roughly comprises three periods: induction of crystal nucleus, crystal growth and steady state transformation.
基金supported by the National Natural Science Foundation of China(21376235)Natural Science Foundation of Liaoning Province(201602740)~~
文摘The synthesis of ferrierite(FER)zeolite using piperidine as an organic structure‐directing agent was investigated.X‐ray diffraction,X‐ray fluorescence,N2‐adsorption,and scanning electron microscopy were used to characterize the crystal phases,textural properties,and particle morphologies of the zeolite samples.The crystallization behavior of the FER zeolite was found to be directly related to crystallization temperature.At150?C,pure FER phase was observed throughout crystallization.At160–170?C,MWW phase appeared first and gradually transformed into FER phase over time,indicating that the FER phase was thermodynamically favored.In the piperidine‐Na2O‐H2O synthetic system,alkalinity proved to be the crucial factor determining the size and textural properties of FER zeolite.Furthermore,the obtained FER samples exhibited good catalytic performance in the skeletal isomerization of1‐butene.
文摘Solid-state crystallization process and mechanism of B-Al-ZSM-5 zeolite from a dry gel of B2O3. A12O3 ? SiO2 in the mixture of ethylamine and water vapour were studied by11B,27Al,29Si,13C MAS NMR, XRD and IR. The extranetwork trigonal BO3 units in the gel play an important role in the process of crystallization. The change of chemical environment around Al atoms is complicated in the process of crystallization. Octahedral Al-O groups existing in the intermediate products do not appear in both the initial gel and final product. Silicon is mainly present as hydroxyl compounds, and the extrastructural Si-O groups detected in the process of crystallization disappear after complete crystallization. Ethylamine plays the role of both template and reactant. It acts with the boron-, aluminum-, and silicon-hydroxyls through hydrogen bonding and promotes the crystallization process. The relative crystallinity of the final & A1-ZSM-5 product is about 93% as measured with11B MAS NMR and IR.
