Energy recovery from banner waste through catalytic pyrolysis over cobalt oxide: Effects of catalyst configuration

Banner waste contributes to a tremendous amount of plastic waste, which requires a proper treatment method. As catalytic pyrolysis is an effective plastic treatment method, this study explored the effects of Co₃O₄ catalyst configuration on the characteristics and energy contents of pyrolytic products of banner waste. In situ configuration (feedstock and catalyst in direct contact) provided intimate contact of pyrolysis vapors with the catalyst, which enhanced thermal cracking of the feedstock and its pyrolyzates. This resulted in higher yields of gas and liquid pyrolyzates and a lower yield of solid residue, compared with ex situ configuration (feedstock and catalyst not in direct contact). The Co₃O₄ catalyst promoted decarboxylation and suppressed decarbonylation. In comparison with in situ configuration, ex situ configuration further enhanced the effects of promoting decarboxylation and suppressing decarbonylation. Wax species (ie, heavy molecules of C_>20) were only found in in situ configuration, most likely because, in ex situ configuration, the heavy carbon molecules form coke deposited on the catalyst. Non-catalytic pyrolysis led to pyrolytic gas with a heating value (14.4 MJ kg⁻¹) that was higher than pyrolytic gases produced in either in situ or ex situ configuration. Using in situ configuration, increased the heating value of pyrolytic liquid (35.4 MJ kg⁻¹) and char (21.3 MJ kg⁻¹), in comparison with using ex situ configuration. This is the first study that examines the impact of catalyst configuration on pyrolysis of banner waste.