High Catalytic Performance of a CeO₂-Supported Ni Catalyst for Hydrogenation of Nitroarenes, Fabricated via Coordination-Assisted Strategy

Abstract

A family of two-dimensional salen-type lanthanide complexes was synthesized through a facile solution diffusion method. The two-dimensional lanthanide complexes were characterized by single-crystal X-ray diffraction (SCXRD) and X-ray photoelectron spectroscopy (XPS) analytical techniques. The SCXRD and XPS analyses reveal that the obtained two-dimensional structures are rich in uncoordinated imine (-CH═N-) groups located on the skeleton of the salen-type organic ligand, which retain strong coordination ability with metal ions. On the basis of this unique feature, a highly dispersed CeO-supported Ni catalyst (Ni/CeO-CAS) with highly strong metal-support interaction was first synthesized via a coordination-assisted synthesis (CAS) method, which exhibits a much better catalytic activity in the hydrogenation of nitrobenzene than the traditional Ni/CeO-IWI catalyst prepared by incipient wetness impregnation (IWI). The origin of the improved catalytic activity of Ni/CeO-CAS as well as the role of Ni@Ce-Hsalen was revealed by using diverse characterizations. On the basis of the comparative characterization results, the superior catalytic performance of Ni/CeO-CAS to Ni/CeO-IWI could have resulted from the smaller and highly dispersed Ni nanoparticulates, the intensified Ni-CeO interaction, the enhanced NiO reducibility, and the higher concentration of oxygen vacancies, favoring the H dissociation and adsorption of the nitrobenzene reactant. The Ni/CeO-CAS catalyst also exhibits high catalytic performance for reduction of diverse nitroarenes to their corresponding functionalized arylamines. We anticipated that this coordination-assisted strategy may provide a new way for preparing other highly oxide-supported catalysts with potential applications in various catalytic reactions.

Catalytic Oxidation of Chlorobenzene over Pd-TiO2 /Pd-Ce/TiO2 Catalysts

“…Both 0.2% Pd /TiO 2 and 0.2% Pd-0.5% Ce/TiO 2 showed PdO with a characteristic spacing of 0.26 nm. The 0.2% Pd-0.5% Ce/TiO 2 sample showed an expected spacing of 0.34 nm for CeO 2 , as also found in the XRD results [30,31]. The average sizes of PdO nanoparticles in the 0.2% Pd/TiO 2 and 0.2% Pd-0.5% Ce/TiO 2 samples were 5.8 and 4.7 nm, respectively, indicating that the particle size of the PdO noticeably decreased after the addition of CeO 2 , which improved the catalytic reaction [32].…”

Rh Catalyzed Selective Hydrogenation of Nitroarenes under Mild Conditions: Understanding the Functional Groups Attached to the Nanoparticles

“…By adjusting the arrangement of atoms on the active surface through alloying, both adsorption and activation energy changed in favorable directions and even for hydrogen passivation metal such as gold . Li and co‐workers fabricated highly dispersed CeO 2 ‐supported Ni catalyst with SMSI, which favors the H 2 dissociation and adsorption of nitroarenes . While the Pt‐Fe 3+ ‐OH interface could suppress the further hydrogenation of imine to amine .…”

“…[8] Li and co-workers fabricated highly dispersed CeO 2 -supported Ni catalyst with SMSI, which favors the H 2 dissociation and adsorption of nitroarenes. [9] While the Pt-Fe 3 + -OH interface could suppress the further hydrogenation of imine to amine. [10] There are also methodologies that provide various protocols for the selective reduction of nitro compounds through special pathway, such as space confined sterically absorption, [11] surface diversities of coordination sites, [12] special location of active metal sites [13] and modifying surface hydrophobic properties.…”

Excellent photocatalytic reduction of nitroarenes to aminoarenes by BiVO4 nanoparticles grafted on reduced graphene oxide (rGO/BiVO4)

“…One of the classical reactions, the reduction of nitro compounds, is based on the use of iron powder and HCl, known as Bechamp reduction process reaction with, however, several important disadvantages such as the difficulty to dispose the formed iron slurry. Catalytic hydrogenation of nitroarenes using H 2 requires high pressure and temperature . Visible light assisted catalysts have included an important section of synthetic methodology same as oxidation of organic compounds, CO 2 reduction, coupling reaction, H 2 evolution and water oxidation in last few years.…”

“…Catalytic hydrogenation of nitroarenes using H 2 requires high pressure and temperature. [11][12][13] Visible light assisted catalysts have included an important section of synthetic methodology [14,15] same as oxidation of organic compounds, [16] CO 2 reduction, [17,18] coupling reaction, [19] H 2 evolution [20] and water oxidation in last few years. Photocatalytic reduction of nitroarenes into aminoarenes employing visible light active heterogeneous photocatalyst is thus very appealing.…”