Photo-thermal catalytic pyrolysis of waste plastics: Investigation into light-induced metal-support interaction

• Light-induced metal-support interaction was verified over prepared photothermal catalysts in photo-thermal pyrolysis of LDPE. • Photoelectrons transfer guaranteed the existence of Ni 0 species and realized moderate metal-support interaction. • High CNTs production of 287 mg/g plastic and H 2 production of 54 mmol H 2 /g plastic were achieved at 700 °C. A novel photo-thermal catalytic pyrolysis of LDPE was conducted with a solar simulator for effective and energy-conserving production. Four photothermal catalysts, including TiO 2 , NiTi(Ni/TiO 2 ), NiAl(Ni/Al 2 O 3 ) and NiTiAl(Ni/TiO 2 /Al 2 O 3 ), were prepared to study the performance on gas and carbonaceous production at variant temperatures (500 °C, 600 °C and 700 °C). NiTiAl reached carbon nanotubes(CNTs) yield of 280 mg/g plastics with simultaneous hydrogen yield of 54 mmol/g even at 700 °C. For the better understanding of light-induced carbon deposition and hydrogen evolution, pyrolysis in pure thermal mode was also carried out over NiTiAl for comparison, where H 2 production of 28 mmol/g and little carbon product was found. It turns out that the introduction of irradiation together with support component deliberately mediated the metal-support interaction in NiTiAl by certain photoelectrons transfer, which was favorable for CNTs growth and hydrogen evolution. It is expected to provide a design strategy of catalysts in solar pyrolysis of carbonaceous feedstock.