Sustainable Co‐Pyrolysis of Waste HDPE and Groundnut Oil Cake in a Vertical Reactor: Synergy Index, Wax Suppression, and Fuel‐Range Hydrocarbon Formation

ABSTRACT

This experimental study investigates the co‐pyrolysis process to understand its potential for resource recovery and renewable energy production. The experiments were conducted using a vertical column reactor at 600°C for 90 min with a 1:1 ratio of each feedstock. The percentage yield of oil, wax, and char was 66.9%, 1.95%, and 14.38%, respectively when HDPE was used along with waste biomass and it was 83.43%, 0%, and 1.26% for oil, wax, and char, respectively, with use of HDPE alone. In comparison to the theoretical oil yield of the feedstock alone, the 1:1 co‐pyrolysis had 17.5% positive oil yield deviation and about 95.1% suppression of wax formation. Co‐pyrolysis oil had an estimated gross calorific value of 40,928 kJ/kg and a C/H ratio of 6.09, which shows its fuel‐range capability. In FTIR analysis, the presence of less oxygen‐containing functional groups in addition to the aliphatic and olefinic hydrocarbons in the co‐pyrolysis oil was indicated. Moreover, GC–MS analysis also confirmed the presence of C6–C18 gasoline and diesel‐range hydrocarbons in addition to the suppression of >C24 hydrocarbons found in GNC pyrolysis suggesting that the interaction between HDPE radicals and pyrolysis intermediates of GNC causes hydrogen transfer and deoxygenation reactions that enhance oil yield and suppress heavy wax fractions.