Influence of Promoters (Fe, Mo, W) on the Structural and Catalytic Properties of Ni/BEA for Guaiacol Hydrodeoxygenation
journal contributionposted on 05.11.2021, 17:05 by Penghui Yan, Xinxin Tian, Eric M. Kennedy, Olga Petrovna Tkachenko, Michael Stockenhuber
Hydrodeoxygenation (HDO) of guaiacol was investigated over BEA-supported bimetallic Ni–Fe, Ni–Mo, and Ni–W catalysts in a continuous-flow reactor. The electronic properties of Ni were significantly modified following the addition of W and Fe as analyzed by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD), which is well in line with density functional theory (DFT) calculations, suggesting that the formation of Ni–Fe and Ni–W alloys is thermodynamically favorable while the generation of a Ni–Mo alloy is unfavored. The HDO over 9 wt % Ni/BEA catalyst was significantly improved following the incorporation of small quantities (<2.2 wt %) of Mo or Fe, while the incorporation of W decreased the HDO rate. The selectivity to hydrogenation products over the Ni–Fe/BEA catalyst was not altered compared to that of Ni/BEA during the hydrogenation of toluene, indicating that the observed increase in guaiacol conversion was engendered by the promotion of the direct hydrogenolysis of guaiacol to aromatics over Ni–Fe species. The hydrogenation and HDO rates of the Ni–Mo/BEA catalyst were both higher than those of Ni/BEA, which was attributed to the increased Ni dispersion promoted by Mo as indicated by similar nickel turnover frequency (TOFNi) values observed over Ni/BEA and Ni–Mo/BEA.
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