Ni/Pd-promoted Al2O3–La2O3 catalyst for hydrogen production from polyethylene terephthalate waste via steam reforming

Abstract

Ni/Pd-co-promoted Al2O3–La2O3 catalysts for selective hydrogen production from polyethylene terephthalate (PET) plastic waste via steam reforming process has been investigated. The catalysts were prepared by impregnation method and were characterized using XRD, BET, TPD-CO2, TPR-H2, SEM, TGA and DTA. The results showed that Ni-Pd-co-impregnated Al2O3–La2O3 catalyst has excellent activity for the production of hydrogen with a prolong stability. The feed conversion of 87% was achieved over 10% Ni/Al2O3 catalyst which increased to 93.87% in the case of 10% Ni-1% Pd/Al2O3–La2O3 catalysts with an H2 fraction of 0.60. The catalyst performance in term of H2 selectivity and feed conversion was further investigated under various operating parameters, e.g., temperatures, feed flow rates, feed ratios and PET concentrations. It was found that the temperature has positive effects on H2 selectivity and conversion, yet feed flow rate has the adverse effects. In addition, PET concentrations showed improved in H2 selectivity in comparison to when only phenol as a solvent was involved. The Ni particles, which are the noble-based active species are more effective, thus offered good hydrogen production in the PET steam reforming process. Incorporation of La2O3 as support and Pd as a promoter to the Ni/Al2O3 catalyst significantly increased catalyst stability. The Ni–Pd/Al2O3–Al2O3 catalyst showed remarkable activity even after 36�h along with the production of carbon nanotubes, while H2 selectivity and feed conversion was only slightly decreased.