Selective Room‐Temperature Hydrogenation of Carbonyl Compounds under Atmospheric Pressure over Platinum Nanoparticles Supported on Ceria‐Zirconia Mixed Oxide

Abstract

A Pt/CeO2‐ZrO2 catalytic system was able to initiate an extremely intense hydrogen spillover providing a huge amount of activated hydrogen (12 mol/mol Pt) at temperatures –50°C ‐ +25°C, which was not observed before. The idea was to use this activated hydrogen for reduction of carbonyl compounds under ambient conditions. Thus, the efficient and selective heterogeneous hydrogenation of carbonyl compounds of different structure, including 5‐hydroxymethylfurfural and cinnamaldehyde, to the corresponding alcohols with quantitative yields was successfully performed over the Pt/CeO2‐ZrO2 catalysts at room‐temperature and atmospheric pressure of H2. The proposed catalysts afforded hydrogenation under significantly milder conditions with a much higher activity and selectivity compared to the commercial catalysts and reported catalytic systems. Hydrogenation of the C=O bond in the presence of a C=C bond proceeded with a high regioselectivity.

Heterogeneous additive‐free highly selective synthesis of 2,5‐bis(hydroxymethyl)furan over catalysts with ultra‐low Pt content

“…Earlier, the spillover effect at temperatures from −50 to 30 °C was described by our group for catalysts with a platinum content of 0.5–1 wt% 15,21,22 . The hydrogen consumption on catalysts with a Pt content as low as 0.25–0.025 wt% in the temperature range from −50 to 30 °C was much lower, and the main H 2 uptake was observed in the temperature range 30–250 °C (Fig.…”

“…The morphological and textural properties of the ceria–zirconia (CZ) carrier are described in our previous work 15–17 and are presented in the Supporting information (Table S1). Unfortunately, electron microscopical study of the sample with the highest metal loading (0.25% Pt/CZ) did not allow us to distinguish platinum nanoparticles due to its low content; only the support nanoparticles can be observed on the high‐resolution transmission electron microscopical images (Supporting Information, Fig.…”

“…1(a)), confirming the fact that the presence of some metals, including platinum, promotes the reduction of oxide supports under much lower temperatures due to the spillover effect 23–25 . It should be noted that the addition of a zirconium component to CeO 2 not only facilitates its redox cycle in CeO 2 –ZrO 2 mixed oxide, 26 but also can lead to the formation of defects at the interface with cerium oxide, providing additional sites for the activation of the carbonyl group of the substrate 15 …”

“…The preparation of catalysts with a platinum content of 0.25–0.025 wt% was performed using the pH‐controlled precipitation method. The detailed technique of carrier and catalysts synthesis is described in our previous work 15 and in the Supporting Information.…”

Monometallic Copper Catalysts for the Hydrogenation of 5-Hydroxymethylfurfural

“…Catalyst Synthesis CeO 2 -ZrO 2 mixed oxide supports were synthesized via the coprecipitation of metal precursors from the working solutions [20]. The initial materials were ZrO(NO 3 ) 2 ⋅ 8H 2 O (99.5%; up to 4% Hf; Acros) as the precursor of zirconium oxide and (NH 4 ) 2 Ce(NO 3 ) 6 (98+%, Alfa Aesar) as the precursor of cerium oxide.…”