Hydrogenolysis of Lignin Model Compounds on Ni Nanoparticles Surrounding the Oxygen Vacancy of CeO₂

Abstract

The cleavage of C–O bonds presents the crucial step for realizing the depolymerization of lignin. Herein, we report that Ni nanoparticles (NiNPs) supported on CeO2 with oxygen vacancies (Ov) show high activity and selectivity in hydrogenolysis of C–O bonds of diphenyl ether (DPE, a lignin model compound), while single-site Ni (SSNi) is nearly inactive in the reaction. Temperature-programmed desorption (TPD) demonstrates that both DPE and H2 can be adsorbed and activated on NiNPs. Density functional theory (DFT) calculation further indicates that the NiNPs are more reactive for H2 and DPE because the Ov at the interface between NiNPs and CeO2 can greatly enhance the adsorption of DPE, but no adsorption of DPE on SSNi was observed. It is identified that the Ni atoms of NiNPs neighboring the Ov of CeO2 are the catalytic sites of the Ni/CeO2 catalyst for the efficient cleavage of C–O bonds in lignin model compounds. This work highlights that the Ni sites neighboring the Ov of CeO2 can act as efficient active sites for rupturing the C–O bonds in lignin models, which can be conducive to the rational design of metal-supported catalysts, especially for the hydrogenolysis of C–O bonds in biomass conversion.

Highly efficient ambient temperature photo-oxidation of CH4 to C1 products over CeO2 supported single-atom Fe with oxygen vacancies

“…As displayed in Fig. 1l, in addition to peaks belonging to gaseous CO at 2117 cm −1 , 15,16 a new peak centered at 1847 cm −1 assigned to linear-type CO adsorbed on single Fe sites (even lower than that at 1888 cm −1 detected on the O v of CeO 2 ) 17 was detected and increased with CO pressure, indicating the existence of a certain number of Fe single sites. In our previous work, we reported that Fe atoms predominantly undergo substitutional doping into the CeO 2 lattice under the current calcination experimental conditions (900 °C and 6 h).…”

Efficient Catalytic Hydroformylation of Alkenes on Rh/CeO2 Catalysts Modulated by CeO2 Morphology

“…As a unique catalyst support material, cerium oxide (CeO 2 ) can maximize the activity of precious metals due to the existence of abundant oxygen vacancy defects. , At the same time, CeO 2 and precious metals can strongly interact, which limits the agglomeration of precious metals on the support. Thus, these metals can stably exist in a highly dispersed form, and lower precious metal loadings can be utilized. , Recently, Li and co-workers used CeO 2 -supported Ni nanoparticles to achieve the efficient catalytic hydrogen hydrolysis of diphenyl ethers . Datye and co-workers realized the oxidation of CO by loading single-atom Pt active sites on CeO 2 .…”

Insight into the Pt Size Dependence of C–O Bond Cleavage in Diphenyl Ether by First- Principles Calculations: From Single Atom to Nanoparticle

“…Li and co-workers reported that the higher activity for the hydrogenolysis of 2-phenoxy-1-phenethanol over carbon-supported Ni nanoparticles was ascribed to the lower H 2 dissociation energy and reduced energy barriers on Ni cluster compared with Ni single-atom in DFT simulations . Xie et al found that the adsorption of diphenyl ether on Ni 10 /CeO 2 (111) was stronger than that on the Ni SA /CeO 2 (111) by comparing the DFT-calculated energies and proposed the reaction mechanism for the DPE hydrogenolysis on Ni 10 /CeO 2 (111) . In these theoretical studies, there is a lack of electronic structure analyses that can be used to reveal the nature of the energy differences.…”