Abstract
In this research, a bimetallic Pt-Ni/CeO2-SiO2 catalyst, synthetized via wet impregnation, was successfully employed for the oxidative steam reforming of ethanol between 300 and 600 °C. The reaction performance of the Pt-Ni catalyst was investigated and compared with the Ni/CeO2-SiO2, Pt/CeO2-SiO2 as well as CeO2-SiO2 sample. The bimetallic catalyst displayed the best results in terms of hydrogen yield and by-products selectivity, thus highlighting the crucial role of active species (Pt and Ni) in promoting ethanol conversion and reaching the products distribution predicted by thermodynamics. The most promising sample, tested at 500 °C for more than 120 h, assured total conversion and no apparent deactivation, demonstrating the stability of the selected formulation. By changing contact time, the dependence of carbon formation rate on space velocity was also investigated.
Highlights
A promising strategy to mitigate the environmental impacts brought by the massive use of fossil fuels consists in the choice of hydrogen as the future energy source for transportation, fuel cells and power stations [1,2]
The bimetallic catalyst displayed the best results in terms of hydrogen yield and by-products selectivity, highlighting the crucial role of active species (Pt and Ni) in promoting ethanol conversion and reaching the products distribution predicted by thermodynamics
At similar operative conditions, other authors found a faster deposition of coke [28,64], even if stability tests were performed for lower TOS [65]: these results demonstrated the competitiveness of the Pt-Ni/CeO2 -SiO2 catalyst in terms of endurance performances
Summary
A promising strategy to mitigate the environmental impacts brought by the massive use of fossil fuels consists in the choice of hydrogen as the future energy source for transportation, fuel cells and power stations [1,2]. Several authors found that the combination of two metals (Ni-Co [19], Rh-Co [20], Cu-Ni [21,22], Pt-Ni [23,24], Pt-Co [25], Rh-Pt [18]) may improve the catalyst performance in the ethanol steam reforming reaction: the addition of a second metal plays a crucial role in enhancing reducibility, preventing sintering and limiting deactivation due to coke formation. Rare earth based oxides, due to the high oxygen mobility and the promotion of strong metal-support interactions, may prevent sintering and deactivation by coke deposits [31]: the formation of oxygen vacancies is based on the reversible redox reaction between Ce4+ and Ce3+ ions, depending on the oxygen excess or defect in the environment [32].
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