Production of alumina based porous ceramics using sodium alginate as gelling agent

Abstract

Porous ceramics are increasingly becoming important in catalytic support and filtration, especially in waste management and recovery of materials. In this report, we reviewd the main processing routes that can be used for the fabrication of macroporous ceramics with tailored microstructure. Emphasis is given to versatile and simple approaches that allow one to control the microstructural features that ultimately determine the properties of the macroporous material. In the present study effort had been given to understand the interrelation of microstructure and specific surface area of millimetric beads of gamma- alumina. Aluminium Oxihydroxide (boehmite) was used to exploit fast gelation with sodium alginate by ion exchange. This gelation mechanism led to the preparation of bodies that can be more easily manipulated than powders. The project work focuses on the production of alumina based porous ceramics and its characterization with 3 different alumina samples having solid loading of boehmite (12-36) percent were prepared by sol-gel process. Alumina beads were calcined in the temperature range (900ᴼC–1100ᴼC) for 2 hours. The beads were then characterized by X-ray Diffraction, Scanning Electron Microscopy, BET surface area and mechanical strength measurement. The microstructure reveals the distribution of the pores inside those beads and the average size of pores. The specific surface area of the beads with 24% and 36 % solid loading at 900ᴼC is found to be 119.50 m²/g and 126.06 m²/g respectively. The present work discusses the most important aspects to take into consideration of the improvement of ã- Al2O3 as a support for catalytic applications. We show that the synthetic route to ã-Al2O3 is the starting point that determines the micro- and macrostructure of the oxide and, consequently, important physical and mechanical properties.