Study on the initial steps of the polyethylene cracking over different acid catalysts

Abstract

The initial steps of the thermal and catalytic cracking of low-density polyethylene (LDPE) at different temperatures and reaction times have been studied in batch operation. The catalysts employed were silica- alumina, USY zeolite and MCM-41. The thermal degradation follows a random scission mechanism with little contribution of isomerization and aromatization reactions; cracking over SiO 2 -Al 2 O 3 shows both products coming from random scission and isomerization processes. On the contrary, USY zeolite favours an end- chain cracking mechanism with pronounced isomerization and aromatization. LDPE degradation over MCM-41 proceeds through a random scission mechanism due to their large pores, while hydrogen transfer reactions involving high molecular weight molecules are also favoured by this catalyst.