Catalytic co-pyrolysis of groundnut de-oiled cake for sustainable production of nitrile, aromatic, and hydrocarbon-enriched pyrolytic oil

Abstract

Catalytic co-pyrolysis of groundnut de-oiled cake (GNOC) with high-density polyethylene (HDPE), low-density polyethylene (LDPE), and waste polycarbonate (P) was studied to optimize pyrolytic oil yield and composition. The effects of temperature, catalyst, and biomass-to-plastic ratios (90:10, 80:20, 70:30) were studied in the presence of molecular sieves (MS) catalyst. Under non-catalytic conditions, lower yields of pyrolytic oil, ∼28 wt%, were obtained. Whereas catalytic pyrolysis enhanced the yields up to ∼40 wt%, and enriched the oil with nitriles, amides, hydrocarbons, and aromatics. Catalytic co-pyrolysis at a 70:30 GNOC-to-LDPE/HDPE ratio produced ∼95% aromatics and ∼85% hydrocarbons in the pyrolytic oil, demonstrating synergistic degradation behavior. Carbon number analysis showed that LDPE favored the synthesis of C₆-C₁₀ hydrocarbons, HDPE extended up to C₂₀, and P contributed to heavier fractions > C₂₀. These findings demonstrate the potential of catalytic co-pyrolysis of GNOC with various plastics and an MS catalyst to produce high-quality, fuel and valuable chemical-rich pyrolytic oils.