Aldoses on Ni/Pd(1 1 1) surfaces: A TPD study

The catalytic production of fuels and chemicals from biomass requires a greater understanding of the chemistry of biomass derived sugars on advanced catalyst surfaces. This study examines the reaction of cellulosic derivative d-glucose and functional surrogates glycolaldehyde and glyceraldehyde on the bimetallic Ni/Pd(1 1 1) surface using temperature programmed desorption (TPD) in ultra high vacuum (UHV). It was found that the primary reaction pathway on the Ni/Pd system for all three molecules was dehydrogenation to produce CO and H2. Additionally, it was found that of the surfaces studied, the reforming activity followed the trend Pd(1 1 1) > Pd-Ni-Pd≈Ni-Pd-Pd > thick Ni/Pd. The Ni terminated surfaces were also found to produce ethylene at high temperatures and saw generally higher temperature and broader H2 desorption peaks, suggesting a higher energy barrier for CH bond scission.

Highlights► Ni/Pd(1 1 1) bimetallic catalysts were prepared with surface and subsurface Ni layers. ► Reaction of glycolaldehyde, glyceraldehyde and glucose was characterized using TPD. ► The main reaction pathway was dehydrogenation forming CO and H2 for all molecules. ► Activity followed the trend Pd(1 1 1). ► Pd-Ni-Pd-Ni-Pd-Pd. ► Thick Ni/Pd.