Fuel Oil Production in Catalytic Pyrolysis of Polyolefins with a Chromium Pillared Clay

HDPE, LDPE and PP are the most produced polyolefins today. As these polymers are mainly used in packaging, their life cycle is short, generating large amounts of post-consumer plastic waste. The purpose of this study was to evaluate the efficiency of chromium pillared clay (CrPILC) as catalyst in pyrolysis of virgin and post-consumer polyolefins (HDPE, LDPE and PP) to obtain fuel oil in diesel fraction rich in n-paraffins. CrPILC was synthesized from a commercial Brazilian clay and an acid-restructured clay (K10) was used for comparison. Assays were performed in a fixed-bed reactor at 450 °C for 15 min. Chemical composition of liquids from pyrolysis was analyzed by Gas Chromatography-Mass Spectrometry (GC–MS) and Gas Chromatography with Simulated Distillation (GC-SIMDIS). Catalytic pyrolysis of polyolefins with K10 generated higher proportions of pyrolytic liquid than CrPILC. The liquids from catalytic pyrolysis with HDPE presented a homologous series distribution of n-alkanes like diesel oil, mainly using CrPILC. Simulated distillation curves from pyrolysis of polyolefins with K10 produced higher contents of light hydrocarbons in diesel range (C9-C24), (~ 80%) than CrPILC (~ 65%). The content of light hydrocarbons in diesel range increased with HDPE (35%), LDPE and PP (20%) in pyrolysis with K10 and 20% in pyrolysis of CrPILC only with HDPE, if compared to thermal cracking of the polyolefins. Cracking results suggest that K10 was more effective for cracking polyolefins, while CrPILC was more selective for cracking HDPE. The content of acid sites and mesopore properties from K10 probably favored the production of paraffinic compounds.