Ni-Mo2C/y-Al2O3 catalysts for syngas production in pyrolysis-dry reforming of plastics - the effect of amine nature on catalyst performance

Pyrolysis combined with dry reforming (PCDR) is eco-friendly technology for plastic waste management, allowing for sustainable production of syngas. Design of suitable catalysts with high performance and stability is crucial for its industrialization. In this work, Ni-Mo2C/γ-Al2O3 catalysts were synthesized using organic–inorganic precursors. Three types of amines (hexylamine – aliphatic linear, cyclohexylamine – aliphatic cyclic, aniline – aromatic) were used as carbon source in the precursor preparation to investigate their effect on catalyst physicochemical properties and its catalytic performance. Catalytic performance of the obtained catalysts was examined in PCDR of model waste plastic mixture. It was revealed that catalytic activity of catalysts prepared with aliphatic amines was higher compared to aromatic aniline, amine commonly used for carbide synthesis. The differences in catalyst properties, which affected their catalytic activity were characterized using N2-adsorption at −196 °C, XRD, H2-TPR, SEM, TG/DTG and CO2-adsorption methods. A correlation was observed between amine molecule complexity and Mo2C crystallite size, significantly affecting hydrogen generation. The less complex the amine, the smaller the crystallite and the increased hydrogen production. Moreover, the use of aliphatic amines resulted in the stronger Ni-support interactions, the increased number of more favorable, larger mesopores as well as the presence of the metallic Mo phase and the lack of unbound carbon in contrast to the catalyst obtained using aniline. The catalyst synthesized using hexylamine increased H2 yield by more than tenfold, syngas yield by more than threefold, and the H2/CO ratio by fivefold, which offers an opportunity for future industrialization of PCDR.