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

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 N-2 adsorption-desorption, XRD, FT-IR, HRTEM, XPS, H-2-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 Ni delta- 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-Ti-S/ATP catalyst synthesized by co-precipitation method exhibited better reducibility and lower surface acidity, as well as produced more Ni delta- species and Ni delta--O-v-Ti3+ interface sites. Then the synergistic effects among the above-mentioned characters made the Ni-Ti-S/ATP catalyst present highest carbon conversion (93.4%) and H-2 yield (77.6%) during SRAA reactions. The analyses of XRD, HRTEM and TG were implemented on used catalysts and discovered Ni-Ti-S/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. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Steam reforming of acetic acid over Ti-modified Ni/Attapulgite catalysts showed promising hydrogen production efficiency, attributed to the synergistic effects among Ti species, Ni active metal, and Attapulgite support, as well as the optimized precipitation sequence determining the surface properties of the catalysts.