Catalytic Thermolysis of Polystyrene over Hydrated Laumontite and its Kinetic Analysis

Abstract

Hydrated Aluminum Silicates (Laumontite) has been studied as a catalyst in the degradation (Catalytic Thermolysis) of polystyrene (PS) at 400oC in a semi batch reactor. Its performance on the degradation was compared with HZSM-5, silica-alumina and also with thermal degradation (thermolysis). Laumontite (HNZ) was as effective as HZSM-5 for the production of liquid oils with carbon numbers of C5-C12, without any severe deactivation. The main product of PS degradation was styrene for both thermolysis and catalytic thermolysis. Among the catalysts tested, silica-alumina showed the highest yield of ethylbenzene and the lowest one of styrene due to its mesopores. Increase in degradation temperature for HNZ resulted in a decrease of selectivity towards ethylbenzene and propylbenzene, but an increase of styrene selectivity with lower yield of styrene dimers. A kinetic analysis by thermo gravimetric analysis was also carried out using a dynamic model. It offered reliable kinetic parameters for the catalytic degradation of PS over HNZ. The apparent activation energy was found to be 350kJ/mol, and the catalytic degradation of PS followed first-order kinetics.