Fabrication and characterization of single phase cordierite honeycomb monolith with porous wall from natural raw materials as catalyst support

A low-cost, single phase cordierite honeycomb monolith whose walls are highly porous has been prepared by the extrusion method using local natural raw materials, as kaolinite and magnesite from Saudi Arabia without need of any organic additives. The characterization of the achieved monoliths has focused on the phase evaluations and microstructures development depending on batch compositions and sintering conditions. Thermal expansion coefficients, microstructures and crystalline structures of the obtained samples have been determined by X-ray diffraction, scanning electron microscopy, FT-IR and thermal dilatometry. Crystalline phases have been also determined by Rietveld analysis. The results show that, synthesis condition of single phase cordierite is extremely narrow by means of both chemical composition and sintering temperature. Single phase cordierite could not have been obtained by using stoichiometric composition for any sintering conditions. Also changing of the sintering temperature as low as 5 degrees C has affected the crystalline phases. Only single phase cordierite has been synthesized by sintering the non-stoichiometric composition at 1320 degrees C for 3 h where the linear thermal expansion coefficient of the sample is 2.07 x 10(-6)/degrees C. Also the fabricated monolith has kept its structure after thermal shock of 300 cycles at 450 degrees C. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.