Hydrogen production from acetic acid steam reforming over Ti-modified Ni/Attapulgite catalysts

Abstract

Steam reforming of bio-oil derived oxygenates is a green and sustainable method for hydrogen production. In this work, hydrogen production from steam reforming of acetic acid (SRAA) was investigated over Ti-modified Ni/Attapulgite (ATP) catalysts that prepared via sequential precipitation technique. The effects of Ti additive, precipitation sequence and Ti-salt precursors (TiCl4, TiOSO4) on the structural and physicochemical properties of catalysts were characterized by N2 adsorption-desorption, XRD, FT-IR, HRTEM, XPS, H2-TPR and NH3-TPD. These results indicated that the interaction among Ti species, Ni active metal and ATP enhanced the reduction performance as well as weakened surface acidity of the Ni/ATP catalyst, and also promoted the electron transfer to form Niδ− species. Obviously, compared with Ti precursor salts, the precipitation sequences played a key role in determining the surface properties of Ti-modified catalysts. Among them, the Ni–TiS/ATP catalyst synthesized by co-precipitation method exhibited better reducibility and lower surface acidity, as well as produced more Niδ− species and Niδ−-Ov-Ti3+ interface sites. Then the synergistic effects among the above-mentioned characters made the Ni–TiS/ATP catalyst present highest carbon conversion (93.4%) and H2 yield (77.6%) during SRAA reactions. The analyses of XRD, HRTEM and TG were implemented on used catalysts and discovered Ni–TiS/ATP catalysts shown promising metal sintering and coke resistance, which mainly caused by the presence of flat Ni–Ti@ATP structures. The possible conversion mechanism of acetic acid in the flat Ni–Ti@ATP structure of co-precipitation Ti-modified catalyst was also elucidated.