Efficient Decarbonylation of Furfural to Furan Catalyzed by Zirconia‐Supported Palladium Clusters with Low Atomicity

Abstract

Decarbonylation of furfural to furan was efficiently catalyzed by ZrO -supported Pd clusters in the liquid phase under a N atmosphere without additives. Although Pd/C and Pd/Al O have frequently been used for decarbonylation, Pd/ZrO exhibited superior catalytic performance compared with these conventional catalysts. Transmission electron microscopy and X-ray absorption fine structure measurements revealed that the size of the Pd particles decreased with an increase in the specific surface area of ZrO . ZrO with a high surface area immobilized Pd as clusters consisting of several (three to five) Pd atoms, whereas Pd aggregated to form nanoparticles on other supports such as carbon and Al O despite their high surface areas. The catalytic activity of Pd/ZrO was enhanced with a decrease in particle size, and the smallest Pd/ZrO was the most active catalyst for decarbonylation. When CeO was used as the support, a decrease in Pd particle size with an increase in surface area was also observed. Single Pd atoms were deposited on CeO with a high surface area, with a strong interaction through the formation of a Pd-O-Ce bond, which led to a lower catalytic activity than that of Pd/ZrO . This result suggests that zero-valent small Pd clusters consisting of more than one Pd atom are the active species for the decarbonylation reaction. Recycling tests proved that Pd/ZrO maintained its catalytic activity until its sixth use.

Wacker Oxidation of Terminal Alkenes Over ZrO2‐Supported Pd Nanoparticles Under Acid‐ and Cocatalyst‐Free Conditions

“…Although Al 2 O 3 -supported Pd displayed high catalytic activity, ap oor materialb alancew as caused by the generation of several dimer byproducts and other polymerizedc ompounds. The use of commercially availableP d/C and Pd(OH) 2 /C resulted in considerably worse yields (Table1,e ntries [11][12]. Therefore, the size of the Pd NPs that were deposited on the metal oxide and the nature of the support could greatlyi nfluence the catalytic performance.…”

“…[8a,f] Very recently,o ur group reported am ethodt od ecarbonylate furfural to furan catalyzed by aZ rO 2 -supported Pd catalyst withouta dditives. [12] In that work, the Pd/ZrO 2 catalytic activity was significantly affected by the Pd particle size. We have also Highly efficient Wacker oxidationofaromatic or aliphatic terminal alkenes into methyl ketones and benzofurans is developed by using reusable Pd 0 nanoparticles (NPs) supported on ZrO 2 under acid-and cocatalyst-free conditions.…”

Pyridinic Nitrogen‐Doped Graphene Nanoshells Boost the Catalytic Efficiency of Palladium Nanoparticles for the N‐Allylation Reaction

“…[10] Supported palladium catalysts are readily separated and recycled through filtration or centrifugation. [14][15][16] Compared with other carriers [e.g.,s ilica, [17] zeolite, [18] metal oxides, [19,20] metalorganic frameworks (MOFs), [21] etc. [11][12][13] Previous studies have demonstrated that the interactions between catalytic speciesa nd the support play significant roles in the catalytic activity and stability.…”

Oxide-Supported Palladium and Gold Nanoparticles for Catalytic C-H Transformations

“…In particular, Pd(OH) 2 /ZrO 2 exhibited the highest activity and selectivity (entry 6). The homogeneous Pd catalysts Pd(OAc) 2 and Pd(OH) 2 showed much inferior catalytic activities to Pd(OH) 2 /ZrO 2 under our conditions due to the formation of Pd black (entries 8 and 9). This result suggested that ZrO 2 support ef ciently stabilized Pd(II) during the reaction.…”