A B S T R A C TThe use of Ni-Fe catalysts for the catalytic pyrolysis of real-world waste plastics to produce hydrogen and high value carbon nanotubes (CNT), and the influence of catalyst composition and support materials has been investigated. Experiments were conducted in a two stage fixed bed reactor, where plastics were pyrolysed in the first stage followed by reaction of the evolved volatiles over the catalyst in the second stage. Different catalyst temperatures (700, 800, 900°C) and steam to plastic ratios (0, 0.3, 1, 2.6) were explored to optimize the product hydrogen and the yield of carbon nanotubes deposited on the catalyst. The results showed that the growth of carbon nanotubes and hydrogen were highly dependent on the catalyst type and the operational parameters. Fe/ γ-Al 2 O 3 produced the highest hydrogen yield (22.9 mmol H 2 /g plastic ) and carbon nanotubes yield (195 mg g −1 plastic ) among the monometallic catalysts, followed by Fe/α-Al 2 O 3 , Ni/γ-Al 2 O 3 and Ni/α-Al 2 O 3 . The bimetallic Ni-Fe catalyst showed higher catalytic activity in relation to H 2 yield than the monometallic Ni or Fe catalysts because of the optimum interaction between metal and support. Further investigation of the influence of steam input and catalyst temperature on product yields found that the optimum simultaneous production of CNTs (287 mg g −1 plastic ) and hydrogen production (31.8 mmol H 2 /g plastic ) were obtained at 800°C in the absence of steam and in the presence of the bimetallic Ni-Fe/γ-Al 2 O 3 catalyst.

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10To explore the mechanism of the influence of Ni-Fe bimetallic catalyst for the 11 producing high-value carbon nanotubes (CNTs) with clean hydrogen from waste 12 plastic pyrolysis, the pyrolysis-catalysis of plastics were performed using a two stage

This is a repository copy of Carbon nanotubes from post-consumer waste plastics: Investigations into catalyst metal and support material characteristics.

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