PREPARATION AND CHARACTERISATION OF ZEOLITIC MATERIALS FROM AHOKO CLAY

Abstract

The process steps followed to achieve the development of zeolitic materials were beneficiation, calcination, formulation (reactant composition), aging and crystallization. The methods of X-ray fluorescence (XRF) for chemical composition, X - ray diffraction (XRD) for crystal phase identification patterns, and adsorption and desorption data for surface area, pore volume and average pore diameters of the zeolite samples were investigated. Presence of Zeolite Y samples with Si02/Ab03 molar ratios of3.72 and 2.57 were developed from Ahoko clay (kaolin) in Kogi State, Nigeria, under hydrothermal conditions and autogenous pressure using an autoclave. The X - ray diffraction (XRD) analysis revealed that there are possibly about five zeolites of interest that can be developed from the Ahoko clay namely zeolite 5A for sample ZY1, synthesized zeolite ZSM-10 for ZY2 and ZY3, synthesized zeolite Y and dealuminated zeolite Yotherwise known as USY zeolite for samples ZY4 and ZY5. Presence of potassium in Ahoko clay had inhibited the growth of these zeolites and therefore the need for its removal in future research works in this area. However, the crystal phases were reduced in ZY6 and ZY7 samples on dealumination as it eliminated the framework and non-framework aluminum hence it resulted in pure quartz (Si02d- The Brunauer, Emmett, and Teller (BET) surface areas of the samples varied from 0.9-91.8 m ig and that for Langmuir varied from 1.0-104.1 m2/g while the total pore volume varied from 0.01-0.14 cm3/g. A constant porosity of 0.5 determined was an indication of consistency in the crystal structure. ZY4 and ZY5 samples were supported on zirconium and used to investigate the conversion of Petroleum Gas Oil (PGO) to distilled fuels. The hydro cracking reaction was carried out in a microreactor at a reaction temperature of 450 °C, contact time of 90 minutes at a catalyst to gas oil ratio of 0.04. It was found that samples ZY4/Zirconium and ZY5/Zirconium catalysts gave a total conversion and total distilled fuels of 44.91 wt. % & 35.48 wt. %, and 45.73 wt. % & 39.39 wt. % respectively, compared to 47.81 wt. % and 36.58 wt. % over unloaded USY zeolite. The hydro cracking activity of ZY5/Zirconium was more than that of ZY 4/Zirconium.