There are generally 3 reasons for CAT clogging and failure:
1) Acute CAT failure is due to un-burnt fuel entering into exhaust system, due to ignition issues etc.
2) Gradual CAT chocking and failure is due to additives in petrol harmful to CAT and high ZInc content in engine oil. Latest SN grade introduced in 2010, has Zn content equal or less than 800 ppm. It is added to enhance lubricating properties of engine oil. With older oil grade rating like SL, the value of Zn is 1200 ppm or higher.