Kaolin as a Source of Silica and Alumina For Synthesis of Zeolite Y and Amorphous Silica Alumina

Endang Sri Rahayu,Suhermina Suhermina,Sabrina Nadina,Wiranto Wiranto,Arief Imanuddin,Gatot Subiyanto,Endang Yuniarti,Rista Ristiani,A.C Kumoro,M.T Phong,M.A Hussain,S.A Roces,A.W Lothongkum,W.R.W Daud,L Yung,X Rong,Hadiyanto Hadiyanto,P.T.S Nam

doi:10.1051/matecconf/201815605002

Abstract

Kaolin is the clay mineral which containing silica (SiO2) and alumina (Al2O3) in a high percentage, that can be used as a nutrient in the synthesis of zeolites and amorphous silica alumina (ASA). The objective of this research is to convert the Belitung kaolin into silica and alumina as nutrients for the synthesis of zeolites and amorphous silica alumina, which are required in the preparation of the catalysts. Silica and alumina contained in the kaolin were separated by leaching the active kaolin called as metakaolin, using HCL solution, giving a solid phase rich silica and a liquid phase rich alumina. The solid phase rich silica was synthesized to zeolite Y by adding seed of the Y Lynde type, through the hydrothermal process with an alkaline condition. While, the liquid phase rich alumina was converted into an amorphous silica alumina through a co precipitation method. Characterization of zeolite and ASA were done using XRD, surface area and pore analyzer and SEM. The higher of alumina in liquid phase as a result of the rising molar of HCL in the leaching process was observed, but it didn’t work for its rising time. Products of ASA and zeolite Y were obtained by using liquid phase rich alumina and solid phase rich silica, respectively, which resulted through leaching metakaolin in 2.5 M HCl at temperature of 100° C for 2 hours.

Highlights

Kaolin is the clay mineral which containing silica (SiO2) and alumina (Al2O3) which are inert and inactive, which can be activated through the process of calcination
Zeolite and Amorphous Silica Alumina (ASA) are built by atoms of Al, Si and O, these materials can be synthesized with raw materials containing silica and alumina compounds
The material for ASA synthesis comprises of mother liquor resulted of leaching metakaolin, and ammonia or sodium hydroxide

Summary

Introduction

Kaolin is the clay mineral which containing silica (SiO2) and alumina (Al2O3) which are inert and inactive, which can be activated through the process of calcination. Zeolite and Amorphous Silica Alumina (ASA) are built by atoms of Al, Si and O, these materials can be synthesized with raw materials containing silica and alumina compounds. Metakaolin is a relatively inexpensive active kaolin, in which the silica and alumina content can be separated through leaching by acid, that will produce silica-rich solids and alumina-rich liquids. The Silica-rich solids with a certain silica/alumina molar ratio are required in the synthesis of zeolites [1]. Both of the process conditions of calcinating kaolin and leaching metakaolin will affect the results of the separation of silica and alumina. The Al sheet would be dissolved, that causes the different environment of the Si atoms to form microporous silica [2]

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