Effect of activated biochar as a low-cost catalyst on the quality of catalytic intermediate co-pyrolysis oil from waste polystyrene and green coconut pericarp

Abstract

Biochar-based catalysts and waste polystyrene were employed to study their effects on both the yield and composition of the oil produced on the intermediate pyrolysis of green coconut (Cocos nucifera L.) pericarp through catalytic co-pyrolysis. Biochar from intermediate pyrolysis was directly employed as a catalyst, but steam-activated biochars with different activation times from single step activation were also studied as low-cost catalysts. The properties of the catalysts were characterized by N2 physisorption, SEM, SEM-EDS, XRD, and ATR-FTIR techniques. From these techniques, AAEM (especially K) and O-containing functional groups were identified on both biochar and activated biochars, but the activated ones presented a higher surface area (>600 m2 g−1). Results from pyrolysis assays confirmed that co-processing biomass and waste plastic leads to a higher yield of oil while greatly shifting the product composition towards less oxygenated compounds. Catalytic co-pyrolysis with low-cost catalysts confirmed that it is possible to attain a high yield of monoaromatics without relying on zeolite catalysts. This effect was attributed to a synergetic effect between waste polystyrene and activated biochar, which ultimately resulted in an oil organic fraction containing up to 60% of xylene in its composition and presenting a HHV of 34.11 MJ kg−1.