Synthesis of Zeolite Nanomolecular Sieves of Different Si/Al Ratios

Abstract

Nanosized zeolite molecular sieves of different Si/Al ratios have been prepared using microwave hydrothermal reactor (MHR) for their greater application in separation and catalytic science. The as-synthesized molecular sieves belong to four different type zeolite families: MFI (infinite and high silica), FAU (moderate silica), LTA (low silica and high alumina), and AFI (alumina rich and silicafree). The phase purity of molecular sieves has been assessed by X-ray diffraction (XRD) analysis and morphological evaluation done by electron microscopy. Broad XRD peaks reveal that each zeolite molecular sieve sample is composed of nanocrystallites. Scanning electron microscopic images feature the notion that the incorporation of aluminum to MFI zeolite synthesis results in morphological change. The crystals of pure silica MFI zeolite (silicalite-1) have hexagon lump/disk-like shape, whereas MFI zeolite particles with Si/Al molar ratios 250 and 100 have distorted hexagonal lump/disk and pseudo spherical shapes, respectively. Furthermore, phase pure zeolite nanocrystals of octahedron (FAU), cubic (LTA), and rod (AFI) shape have been synthesized. The average sizes of MFI, FAU, LTA, and AFI zeolite crystals are 250, 150, 50, and 3000 nm, respectively. Although the length of AFI zeolite rods is in micron scale, the thickness and width are of a few nanometers.

Nanoscale Features of Zeolite Fillers Enhance the Depth of Cure, Optical Properties, and Mechanical Properties of 3D-Printed Polymer Composite Structures

“…The procedure is detailed in the Supporting Information (Figure S1). 2 Determined by X-ray fluorescence spectrometry (XRF). The transmittance of the cured composites (after photopolymerization) was studied by a JASCO V750 UV−vis spectrometer.…”

“…The general chemical formula of zeolite nanomaterials is M 2/ n O·Al 2 O 3 · x SiO 2 · y H 2 O, where x is always equal to or greater than 2 and n is the valence of the extra-framework cation M . The Si/Al ratio varied between 1, in type-A zeolite, and infinite, in silicalite-1, for example . The presence of trivalent aluminum induces negative charges to the framework that need to be compensated by extra-framework cations (compensation cations). , Zeolite science covers a wide range of applications: gas separation, water decontamination, catalysis, biomedicine, − fields of optics and electronics. , For industrial-scale use, zeolite powders must be shaped.…”

Extraction of Value-Added Minerals from Various Agricultural, Industrial and Domestic Wastes

“…Yadav et al reported the extraction of nanosilica from fly ash tiles using the alkali fusion method [ 80 ]. Silica can be used in the production of glass and ceramics [ 80 ], in drug delivery [ 81 ], and used in medicine, foundries, adsorbents, catalytic processes [ 82 ], and molecular sieves [ 83 ]. Silica is nontoxic and mesoporous, meaning it can be readily used in various industries.…”

Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts

“…2.1.1. Zeolite Synthesis A conventional hydrothermal synthesis was used to achieve the FAU type zeolite was followed according to [29]: (1) Al(OH)3•xH2O (98%, Aldrich) as Al2O3 precursor was dissolved in a NaOH (98%, Sigma-Aldrich) and deionized water solution. (2) Colloidal silica (Ludox HS-40, 40 wt%, Aldrich) as SiO2 precursor was added to solution (1).…”