The Role of Metallic Copper in the Selective Hydrodeoxygenation of Glycerol to 1,2‐Propanediol over Cu/ZrO₂

Abstract

A series of Cu/ZrO2 catalysts with nominal CuO loadings of 5, 10, 18 and 31 wt.% was synthesized by co‐precipitation, characterized and applied in the hydrodeoxygenation of glycerol under mild reaction conditions (200 °C, 25 bar H2). These catalysts were highly selective for the cleavage of C−O bonds while preserving C−C bonds leading to 95 % selectivity to 1,2‐propanediol. The conversion of glycerol was observed to be linearly correlated with the specific copper surface area derived from N2O frontal chromatography. The reaction was found to occur through the dehydration of glycerol to acetol followed by its hydrogenation to 1,2‐propanediol. Metallic copper was identified as the active site for both reactions suggesting the acid ZrO2 sites to be blocked by water. Reusability studies showed that the catalyst was relatively stable and the conversion decreased by only 18 % after three cycles.

Platinum–copper single atom alloy catalysts with high performance towards glycerol hydrogenolysis

“…Although several studies have been focused on active sites and corresponding reactive pathway for glycerol hydrogenolysis to 1,2-PDO, it is still a great challenge to identify and understand intrinsic active sites of bimetallic alloy structure, owing to the complicated reaction pathway 10,33,47–49 . Herein, the promotional catalytic behavior of PtCu–SAA was revealed via a comprehensive study including in situ glycerol-XAFS, in situ glycerol-DRIFTS experiments and DFT calculations.…”

Valorization of Biomass‐derived Small Oxygenates: Kinetics, Mechanisms and Site Requirements of H2‐involved Hydrogenation and Deoxygenation Pathways over Heterogeneous Catalysts

“…In addition, Gabrysh et al. observed a very good linear correlation between the conversion of glycerol and the specific Cu surface derived from N 2 O frontal chromatography (Figure ), clearly indicating that the RDS can occur on a metallic Cu surface ,…”

“…Deployment of dopants (e. g., B 2 O 3 ) or supports (e. g., ZnO,, ZrO 2 ) that substantially interact with the main active phase or even form intermetallic phases helps to stabilize the metal particles against deactivation. Such catalyst ingredients can also confer higher catalytic activities to the main metal (e. g., Cu).…”

“…The key debate is about which route is dominant in the formation of acetol, i. e., direct dehydration (facilitated in acidic conditions) or an indirect route involving dehydrogenation of glycerol to form glyceraldehyde or dihydroxyacetone intermediates on metal surfaces, followed by their dehydration and subsequent hydrogenation into acetol. Regardless of the implicated requirements for metal‐acid/base bifunctionality and perhaps also close proximity of the two functions (when the diffusivity of shuttling intermediates is low or their binding is very strong) in such mechanisms, some reports have indicated that metallic Cu surfaces (either Cu powder derived from H 2 reduction of CuO or a Cu foil) alone could catalyze the dehydration step,, presumably via basic alkoxide species (evidenced in several surface science studies). In addition, Gabrysh et al.…”

Copper Zinc Aluminate Synthesized by Sol‐Gel Method with Polyacrylic Acid as Catalysts for Glycerol Hydrogenolysis

“…This is consistent with previous literature on the hydrogenolysis of glycerol to 1,2-propanediol over Cu/ZnO, [9,37] Cu/SiO 2 [18,19] and Cu/ZrO 2 . [23] The concentration of active sites is correlated to the Cu loading and particle size. This also explains the lower conversion observed with 21CuÀ S1 as the main particle size obtained by N 2 O chemisorption is large (46 nm).…”