Abstract
[Display omitted]
•Balanced Lewis and Brønsted sites in impregnated catalysts promote deoxygenation.•Ni-Pt catalysts enhanced HDO activity and catalyst stability.•Pt addition mostly improved Ni dispersion, boosting alkane selectivity.•The formation of Ni-Pt clusters with high Pt content diminished the HDO activity.•SPP catalysts achieved improved stability and preserved hydrocarbon chains.
This study focused on optimizing nickel-rich MFI zeolite catalysts for the hydrodeoxygenation (HDO) of bio-oils, a sustainable fuel production method that minimizes carbon loss. While Ni-Zeolite catalysts deoxygenate effectively, they are prone to coking. This research aimed to improve HDO selectivity and catalyst stability by exploring bimetallic formulations, modifying zeolite textural properties, and optimizing metal loading. Ion-exchanged catalysts generally performed poorly due to reduced Brønsted acidity and low nickel content. In contrast, impregnated catalysts with high nickel loading and strong dual Lewis and Brønsted acidity proved superior for HDO. In general, platinum co-loading enhanced metal dispersion and stability, leading to higher alkane selectivity and reduced coking. However, when a relatively higher loading of Pt (∼ 0.5 wt.%) was used for SPP-IWI catalysts, Ni-Pt clusters formed, which were found to be detrimental for HDO activity. The 9.75-Ni-0.25-Pt-SPP-IWI catalyst was the most stable, achieving 97.6 % relative abundance of alkanes after 24 h of reaction, due to its mesoporous SPP morphology, better metal dispersion, and weaker acidity. Overall, the findings highlight that successful HDO catalysis requires a precise balance of metal loading, dispersion, and the physicochemical properties of the zeolite support for optimal activity, selectivity towards diesel-range alkanes, and enhanced stability.