Sol-gel Ni-based/γ-Al2O3 as efficient catalysts for toluene reforming: Catalytic activity during long-term experiments and in presence of H2S

Last decades, the valorization of biomass became a topic of interest, and especially the production of syngas by the catalytic reforming of biomass. But one drawback for a large-scale development is the associated production of tars.
This work focuses on the catalytic reforming of tars present in bio-syngas reactors. Efficient Ni-based/γ-Al2O3 catalysts were developed in previous studies by an aqueous sol-gel process. Here, four of those catalysts, exhibiting promising catalytic properties for toluene reforming (used as tar model molecule), were further evaluated on long-term experiments and under H2S. Indeed, long-term performance and resistance to poisoning are two key properties of catalysts for industrial applications. One commercial catalyst, HifuelTM, was also evaluated for comparison. The results showed that the pure Ni/γ-Al2O3 catalyst presented a low deactivation throughout 30 h of experiment with neither Ni particle size nor support crystallinity alteration. All co-doped Ni/γ-Al2O3 catalysts were more resistant against deactivation than the pure Ni/γ-Al2O3 catalyst. As only amorphous carbon was deposited, an easy regeneration was performed by heating the catalysts 2 h at 650 °C under air. The catalytic activity remained unchanged in similar 30 h-experiment.
Contrarily, the commercial HifuelTM catalyst underwent a strong and quick deactivation by the formation of filamentous carbon. The regeneration under air was not sufficient to regenerate the catalyst.
The Ni/γ-Al2O3 catalyst activity was assessed in the presence of H2S. The results showed that the toluene conversion was only slightly affected by the presence of H2S in the syngas mixture, highlighting its very good resistance to poisoning.