An investigation into the crystallization of low-silica X zeolite

Abstract

The crystallization of low-silica X (LSX) zeolite with FAU topology was examined under hydrothermal synthesis conditions. PXRD was employed to follow the evolution of the long-range ordering of the gel. Raman spectra provided information on various ring and cage species existing in the gel. 27 Al and 29 Si solid-state NMR spectroscopy was utilized to monitor the change in local environment of tetrahedral sites. The results indicate that an amorphous aluminosilicate phase was formed immediately upon mixing different reactive species. Hydrothermal treatment led to the formation of sodalite-cage like species and the species with larger cavities, joint four-member rings (4Rs) and branched 4Rs, which are the structural building units of the FAU framework. These units were assembled into the crystalline structure of LSX zeolite. 23 Na and 39 K solid-state NMR results show that the transformation process was accompanied by the changes of the local structure of hydrated Na ? and K ? ions. The two types of cations may work synergistically to template the crystallization of LSX zeolite.

Synthesis of C4 and C8 Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

“…The 27 Al and 29 Si spectra for MgO‐KNaX‐0.99 agree with those of KNaX reported in Ref. , which again demonstrates that MgO‐KNaX‐0.99 retains an unchanged zeolite structure. Interestingly, the intensity of all diffraction peaks decreased as the MgO content increased from 1.14 to 1.32.…”

Electrochemical sensor based on low silica X zeolite modified carbon paste for carbaryl determination

“…Non-enzymatic methods remain a very attractive option, capable to provide quantitative detection of carbaryl with a low cost and short analysis time. Zeolites, identified as microporous crystalline aluminosilicate materials [25] , widely used for their high surface area, ion exchange capability, adsorptive capacity, and molecular sieving ability, are considered as interesting materials, which can be exploited in the development of modified electrodes. Zeolite modified electrodes were used as sensors for different reasons explained in the paper of Walcarius [26] .…”

Organic‐Free, ZnO‐Assisted Synthesis of Zeolite FAU with Tunable SiO2/Al2O3 Molar Ratio

“…[20][21][22][23][24] Also, the tailor of SiO 2 /Al 2 O 3 molar ratio can be achieved through post synthesis modification (dealumination), however,i tw ill give rise to the appearanceo fm esoporosity and ar eduction of crystallinity, which is detrimental to the separation performance. [31,32] Presumably,i norganic cation can serve as structure-directinga gent in the target-oriented synthesis of zeolite with particular properties. Also, some alkali ions such as potassium and sodium have been utilized for selective growth of zeolite with low SiO 2 /Al 2 O 3 molar ratio.…”

“…Also, some alkali ions such as potassium and sodium have been utilized for selective growth of zeolite with low SiO 2 /Al 2 O 3 molar ratio. [31,32] Presumably,i norganic cation can serve as structure-directinga gent in the target-oriented synthesis of zeolite with particular properties. [33][34][35] Inspired by these studies, here we develop an ovel approachf or the synthesis of zeolite FAU, the SiO 2 /Al 2 O 3 molar ratios can be adjusted between ca.…”