The Hydrogenation of Crotonaldehyde on PdCu Single Atom Alloy Catalysts

Abstract

Recyclable PdCu single atom alloys supported on Al2O3 were applied to the selective hydrogenation of crotonaldehyde to elucidate the minimum number of Pd atoms required to facilitate the sustainable transformation of an α,β-unsaturated carbonyl molecule. It was found that, by diluting the Pd content of the alloy, the reaction activity of Cu nanoparticles can be accelerated, enabling more time for the cascade conversion of butanal to butanol. In addition, a significant increase in the conversion rate was observed, compared to bulk Cu/Al2O3 and Pd/Al2O3 catalysts when normalising for Cu and Pd content, respectively. The reaction selectivity over the single atom alloy catalysts was found to be primarily controlled by the Cu host surface, mainly leading to the formation of butanal but at a significantly higher rate than the monometallic Cu catalyst. Low quantities of crotyl alcohol were observed over all Cu-based catalysts but not for the Pd monometallic catalyst, suggesting that it may be a transient species converted immediately to butanol and or isomerized to butanal. These results demonstrate that fine-tuning the dilution of PdCu single atom alloy catalysts can leverage the activity and selectivity enhancement, and lead to cost-effective, sustainable, and atom-efficient alternatives to monometallic catalysts.

Recent advances in single-atom alloys: preparation methods and applications in heterogeneous catalysis

“…Generally, in the case of reduced Cu nanowires or nanoparticles, their color turns to dark gray after the introduction of precious metal salts, suggesting the replacement of Cu by Pt or Pd during the GR reaction and formation of CuPt and/or CuPd SAAs. 51 In terms of reaction media, besides dilute water, dimethyl sulfoxide has been used as a polar aprotic solvent to prevent some host particles from agglomerating in distilled water. 50 However, Mohl et al found that Pt and Pd ions tended to aggregated to form the corresponding nanoparticles in ethanol solvent.…”

“…Zhang et al prepared the 0.1Pt–Cu/SiO 2 SAA, where Pt was isolated as single atoms and formed the Pt–Cu alloy phase. 65 They found that only 0.1 wt% isolated Pt with the surrounding Cu atoms improved the dispersion of Cu, increased the Cu + /Cu 0 ratio and enhanced hydrogen activation without causing the C–C cleavage side reaction. Consequently, PtCu-SAA catalysts afford a reduced reaction temperature, unique ethanol selectivity as high as 76.7% and promising stability of over a 700 h time on stream in the methyl glycolate reaction.…”

Nanocatalysis for Environmental Protection, Energy, and Green Chemistry

“…In this context, this Special Issue compiled 11 high-quality contributions [6][7][8][9][10][11][12][13][14][15][16] (10 collected from PSC participants and 1 from others), covering recent research progress in the titled theme. These articles are briefly discussed below.…”

“…The selective hydrogenation of crotonaldehyde was studied by Kyriakou and coworkers [13] on recyclable PdCu single atom alloys supported on Al 2 O 3 to elucidate the minimum number of Pd atoms required to facilitate the sustainable transformation of an α,β-unsaturated carbonyl molecule. By diluting the Pd content of the alloy, the reaction activity of Cu nanoparticles can be accelerated, enabling more time for the cascade conversion of butanal to butanol.…”