Understanding hydrogen pressure control of furfural hydrogenation selectivity on a Pd(111) model catalyst

• Published in: Journal of catalysis 2023-05, Vol.421 (C), p.55-64
• Main Authors: Bavisotto, Robert, Roy, Sree Pradipta, Hopper, Nicholas, Tysoe, Wilfred T.
• Format: Article
• Language: English
• Subjects: 09 BIOMASS FUELS; Biomass; Chemistry; ENGINEERING; Furfural; Hydrogenation; Hydrogenation. Pd model catalysts; Infrared spectroscopy; Pd model catalysts; Selectivity
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2023.03.010

[Display omitted] •Proposed from theory that furfural selectivity depends on hydrogen pressure.•Selectivity change confirmed using a Pd(111) model catalyst used for theory.•Orientation change confirmed by infrared spectroscopy on the same sample. We investigate the postulate that hydrogen pressure influences the furfural hydrogenation selectivity on palladium to form decarbonylation products at low hydrogen pressures, but 2-methyl furan at higher pressures. This change is caused by co-adsorbed hydrogen changing the orientation of adsorbed furfural; low hydrogen coverages favor flat-lying furfural, higher coverages form tilted species. This was tested for hydrogenation of furfural on a Pd(111) single crystal. The product distribution agreed with the postulate, with 100% selectivity to furan and tetrahydrofuran for low hydrogen pressures, with 2-methyl furan increasing with hydrogen pressure. The origin of the effect is explored using reflection–absorption infrared spectroscopy. This showed that co-adsorbed hydrogen influenced the orientation in a way predicted by theory. It was also found that other co-adsorbates displayed similar effects implying that a range of molecules in the reaction mixture could have significant effects on the furfural selectivity.