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DEVELOPMENT OF PILOT-SCALE REACTOR FOR THE PRODUCTION OF ALUMINIUM HYDROXIDE FROM ALUM DERIVED FROM KANKARA KAOLIN FOR ZEOLITE Y SYNTHESIS

ABSTRACT

This work wasaimed at the design and fabrication of a pilot scale reactor for the production of aluminium hydroxide from aluminium sulphate obtained from Kankara kaolin for use in Zeolite Y synthesis. XRD, XRF and BET analyses were carried out on the aluminium hydroxide first prepared at bench scale and pilot scale. The aluminum hydroxide precipitated on a laboratory bench scale at the pH value of 6 was found to be amorphous while that precipitated at pH value of 7 was found to be a crystalline mix of boehmite and bayerite.The BET surface area of aluminium hydroxide precipitated at the laboratory bench scale was found to be 78.275m2/g for a pH value of 6 and 209.799m2/g for a pH value of 7. The effect of temperature on the amountof aluminium hydroxide precipitated was found to be marginal.From the kinetic studies of the precipitation reaction for aluminium hydroxide, the reaction was found to bepseudo-first order with respect to aluminium sulphate. The activation energy and pre-exponential factor of the precipitation reaction were found to be 102kJ/mole and 1.15x1014/sec respectively.Zeolite Y was synthesized using the aluminium hydroxide produced from Kankara kaolin on a laboratory bench scale. A pilot scale semi-batch reactor was designed for the production of aluminium hydroxide and a conversion of 99.98% of aluminium sulphate reactant was obtained. A pilot scale semi-batch reactor with a capacity of 10.448kg per day for the production of aluminium hydroxide was fabricated and test run, and produced good quality aluminium hydroxide with a BET surface area of 97.73m2/g for the first run and 227.779m2/g for the second run. The product from the pilot scale reactor was found to be a mixture of crystalline and amorphous phases for the first run, and a purely crystallinemix of bayerite and boehmite for the second run.

CHAPTER ONE

INTRODUCTION

The need for an increase in the lighter fractions obtained during petroleum processing led to the cracking of the heavy oil fractions gotten from distillation. There are two methods by which this is achieved which are thermal cracking and catalytic cracking. Over the years catalytic cracking has surmounted thermal cracking as the principal process adopted for the cracking of heavier oil fractions. This is due to the effect of the catalyst in catalytic cracking that lowers the activation energy of the chemical reactions, thereby enabling the conversion of the heavy oil fractions at relatively low temperatures of 500-6000C compared to 750-9000C obtained in thermal cracking. Also, there is an improved yield and quality of product obtained by catalytic cracking as compared with thermal cracking.

Catalytic cracking occurs in a fluid catalytic cracking (FCC) unit in the presence of a catalyst. The catalyst is made up of zeolite dispersed in a catalyst matrix, binders and fillers. The catalyst matrix is primarily made up of active alumina. The relative percentages of these components in catalyst formulation affect the performance of the catalyst. These zeolites are incorporated in the matrix because alone they are expensive and catalytically too active to be used in FCC units of practical dimensions due to severe heat transfer requirements.

Alumina is widely used in a variety of industrial fields due to its excellent physical and chemical properties. Aluminas are used in catalysts and as support for catalysts due to their large surface area, superior chemical activity and low cost.