High Performance and Active Sites of a Ceria‐Supported Palladium Catalyst for Solvent‐Free Chemoselective Hydrogenation of Nitroarenes

Abstract

Cerium oxide‐supported palladium catalysts (Pd/CeO2) prepared by a simple impregnation method exhibit exciting catalytic activity and high chemoselectivity for the solvent‐free hydrogenation of a variety of substituted nitroarenes including the reducible functional groups to the corresponding aromatic amines under mild reaction conditions. Taking nitrobenzene as an example, the Pd/CeO2 catalyst can afford aniline yields of >99 % with turnover frequencies as high as 11 411 h−1 and 69 824 h−1 at 40 °C and 100 °C, respectively. Pd2+ ion species exist as isolated single atoms with −Pd2+−O2−−Ce4+− linkages on the surface of PdxCe1−xO2−σ solid solution and are found to be active sites for the selective hydrogenation of nitroarenes in the absence of solvent. The superior catalytic performance can be attributed to the cooperative effect between Pd2+ ions and unique surface sites of CeO2. A possible mechanism is proposed for the hydrogenation of nitroarenes with H2 over the Pd/CeO2. The Pd/CeO2 catalyst can be recovered easily and reused for at least seven recycling reactions without loss of catalytic properties.

Biomass Sucrose‐Derived Cobalt@Nitrogen‐Doped Carbon for Catalytic Transfer Hydrogenation of Nitroarenes with Formic Acid

“…To date, supported catalysts such as noble-metal catalysts, non-noble metal catalysts, and metal-free catalysts have been reported for catalytic hydrogenationo fn itroarenes. [4][5][6][7][8] For example, Doherty et al reported phosphine-decorated, polymer-immobilized, ionic-liquid-stabilized palladium nanoparticles (NPs) for highly efficient hydrogenation of nitroarenes. [9] Wang and co-workers fabricated heterogeneous nonnoble metal nickel-molybdenum oxide catalystss upported on ordered mesoporous silica SBA-15t hat exhibited excellent catalytic activity for catalytic hydrogenation of nitroarenes with hydrazineh ydrate as hydrogen donor.…”

Ultra‐Small Noble Metal Ceria‐Based Catalytic Materials: From Synthesis to Application

“…There are À Pd 2 + À O 2À À Ce 4 + -linkages formed between Pd 2 + ion and Pd x Ce 1-x O 2-σ , and Pd 2 + existed as isolated single atom. [26] Above all, impregnation method combined with high temperature calcination can effectively synthesize atomically dispersed catalysts. Furthermore, Ag/CeO 2 was also prepared by incipient wetness impregnation method followed by calcination at relatively low temperature of 500°C.…”

“…As shown in Figure 9b, when the reaction time is 3 h, the conversion of nitrobenzene and the selectivity of aniline reach 100 %. Besides, after 7 times of reaction cycle, the selectivity and conversion rate don't decrease significantly, suggesting the good recirculation performance (Figure 9c) [26] …”

“…Besides, after 7 times of reaction cycle, the selectivity and conversion rate don't decrease significantly, suggesting the good recirculation performance (Figure 9c). [26]…”

“…Shi and his co‐workers prepared Pd/CeO 2 by impregnation method, which exhibited high catalytic activity and chemoselectivity for reduction substituted nitroarenes into aromatic amines. There are −Pd 2+ −O 2− −Ce 4+ ‐linkages formed between Pd 2+ ion and Pd x Ce 1‐x O 2‐σ , and Pd 2+ existed as isolated single atom [26] . Above all, impregnation method combined with high temperature calcination can effectively synthesize atomically dispersed catalysts.…”