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

4 years ago

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

Xionggang Lu, Xueguang Wang, Weizhong Ding, Xiujing Zou, Xiuxiu Shi, Xingfu Shang

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. Solvent-free hydrogenation: Cerium oxide-supported palladium catalysts exhibit exciting catalytic activity and high chemoselectivity for solvent-free hydrogenation of a variety of substituted nitroarenes under mild reaction conditions. Pd2+ ions on the surface of PdxCe1−xO2−σ solid solutions are found to be the active sites. The superior catalytic performance can be attributed to the cooperative effect between the Pd2+ ions and unique surface sites of CeO2.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/cctc.201700631