The Study Of Deactivation And Regeneration Of A Fluid Cracking Zeolite Catalysts

Ip Okoye

doi:10.4314/gjpas.v15i1.44888

Abstract

The catalytic activities of modified and unmodified sodium Y-Zeolites catalysts was investigated. Modification by framework dealumination and gallium oxide incorporation led to an increase in catalytic activity. The catalytic activities of both parent and the modified samples were reduced in a time dependent manner due to coke deposition. Incorporation of gallium oxide altered the reaction pathways of C8 intermediates from n-butane reactions, thus producing more aromatic products. However, Ga2O3 in excess of 1% resulted in a large decrease of catalytic activity due to loss in Bronsted acidity. As Bronsted sites are removed, direct protonation of the alkane became difficult and catalytic activity was lowered at high Ga2O3 loading. The oxygen adsorption isotherms of the various coked catalysts showed that the deactivation process involved blockage of the zeolite pore sites by the deposited coke. Interestingly, regeneration of the coked sample was seen to completely restore the catalytic activity of both samples.

Highlights

In recent years molecular sieve catalysts have assumed an important role in industrial catalysis
Early work on the kinetics of paraffin cracking on amorphous silica-alumina catalysts showed that simple first- order kinetic expression can only approximate experimental results
One of the major problems associated with the use of zeolites as catalysts in hydrocarbon conversion is coke formation, which reduces the activity of the catalysts

Summary

Introduction

In recent years molecular sieve catalysts have assumed an important role in industrial catalysis. One of the major problems associated with the use of zeolites as catalysts in hydrocarbon conversion is coke formation, which reduces the activity of the catalysts. Deactivation by poisoning and pore plugging has been attributed to coke formation/deposit during cracking reactions, (Gates et al 1979 and Haag 1994).

Results

Conclusion