Microwave-intensified catalytic upcycling of plastic waste into hydrogen and carbon nanotubes over self-dispersing bimetallic catalysts

Abstract

The value-added utilization of plastic waste is a powerful way to effectively manage plastic waste and achieve a circular economy. However, high-performance catalysis often requires suitable substrate catalysts or complex processes, while low-energy consumption plastic upcycling technology is also urgently needed. In this study, various cheap and self-dispersing highly active iron-cobalt–nickel-monometallic and bimetallic functional catalysts were synthesized through a simple and fast one-step method for catalytic upcycling of plastic into hydrogen and carbon nanotubes. Results indicated that Ni₁Fe₃O_x, Ni₁Co₃O_x and Ni₃Co₂O_x are the most efficient catalysts, realizing hydrogen yield as high as 60.2 mmol g-1 plastic, 63.2 mmol g-1 plastic, 63.5 mmol g-1 plastic and high selectivity of 79.4 vol%, 81.4 vol% and 83.7 vol%, respectively, for microwave-intensified catalytic dehydrogenation of LDPE, the hydrogen yield of which is almost 2–3 times that of traditional thermal catalysis. More importantly, a high hydrogen yield of 44.1 mmol g-1 plastic is also achieved when the feedstock is extended to the landfill mixed plastics waste. These results demonstrate that the synergies of self-dispersing bimetallic catalysts are promising for plastic waste upcycled via microwave-intensified catalysis.