Hydrothermal Synthesis of Zeolite a Using Non-Calcined Diatomite

Abstract

Optimization and reduction of zeolite A synthesis costs are the focus of several studies. Attention has been given to the use of residues and natural materials rich in Si and Al, such as diatomite. Diatomite needs to be calcined above 500°C to be used, which increases processing costs. This study aimed at evaluating the use of diatomite without calcination in preparing zeolite A. Alkaline hydrothermal synthesis melting and 24 h of crystallization were carried out. The materials were characterized by XRD (X-ray powder diffraction), XRF (X-ray fluorescence), BET (N2physisorption) and SEM (Scanning Electron Microscopy). XRD data and refinement show that the obtained material presents 99.84% crystallinity, average crystallite size of 54.92 nm, and a semi-quantitative percentage of 79% zeolite A. SiO2and Al2O3contents in the prepared sample proved the ratio SiO2/Al2O3= 2. The micrographies show cubic particles and agglomerated sodalite.

LTA zeolite synthesis using natural materials and its evaluation by Green Star methodology

“…Besides, we remark that neither diatomites nor perlite were pre-treated in this synthesis, being an advantage to the use of kaolinite or rice husk [26,27]. It is important to notice too that this is the shortest time reported with untreated diatomite, as the recent articles reporting other hydrothermal synthesis conditions reached the LTA topology in 24 h [16,28].…”