Fabrication of Carbon Nanotubes Derived from Waste Tire Pyrolytic Carbon and Their Application in the Dehydrogenation of Methylcyclohexane to Produce Hydrogen

The accumulation of waste tires has resulted in very urgent environmental problems. Pyrolysis has been regarded as a green eco-friendly technology to deal with waste tires, and it is vital to make use of the pyrolysis carbon. Herein, we propose a new way to utilize pyrolysis carbon, to prepare carbon nanotubes with the help of ferrocene. The optimal preparation processes were determined by optimizing the parameters including the solvent, temperature, time, etc. The results of scanning electron microscopy and transmission electron microscopy evidenced the successful formation of carbon nanotubes. Meanwhile, the Brunauer–Emmett–Teller (BET) method and N2-adsorption showed that the yielded carbon nanotubes featured a large surface area and abundant pore structure in comparison with the pyrolytic carbon. Finally, the as-prepared carbon nanotubes were applied as the supports for Pt-based catalysts for the dehydrogenation of methylcyclohexane to produce hydrogen. The results showed that the Pt/carbon-nanotubes catalyst exhibited the highest conversion of methylcyclohexane (28.6%), stability, and hydrogen evolution rate (336.9 mmol/gPt/min) compared to the resulting Pt/commercial-activated-carbon (13.6% and 160.2 mmol/gPt/min) and Pt/pyrolytic-carbon catalysts (0.19% and 2.23 mmol/gPt/min).