Hydrogenative Ring-Rearrangement of Furfural to Cyclopentanone over Pd/UiO-66-NO2 with Tunable Missing-Linker Defects

Abstract

Upgrading furfural (FAL) to cyclopentanone (CPO) is of great importance for the synthesis of high-value chemicals and biomass utilization. The hydrogenative ring-rearrangement of FAL is catalyzed by metal-acid bifunctional catalysts. The Lewis acidity is a key factor in promoting the rearrangement of furan rings and achieving a high selectivity to CPO. In this work, highly dispersed Pd nanoparticles were successfully encapsulated into the cavities of a Zr based MOF, UiO-66-NO2, by impregnation using a double-solvent method (DSM) followed by H2 reduction. The obtained Pd/UiO-66-NO2 catalyst showed a significantly better catalytic performance in the aforementioned reaction than the Pd/UiO-66 catalyst due to the higher Lewis acidity of the support. Moreover, by using a thermal treatment. The Lewis acidity can be further increased through the creating of missing-linker defects. The resulting defective Pd/UiO-66-NO2 exhibited the highest CPO selectivity and FAL conversion of 96.6% and 98.9%, respectively. In addition, the catalyst was able to maintain a high activity and stability after four consecutive runs. The current study not only provides an efficient catalytic reaction system for the hydrogenative ring-rearrangement of furfural to cyclopentanone but also emphasizes the importance of defect sites.

Recent advances in metal–organic framework based heterogeneous catalysts for furfural hydrogenation reactions

“…Wang and their co-workers prepared highly dispersed Pd particles encapsulated in UiO-66-NO 2 (Pd/UiO-66-NO 2 ) by a double-solvent method followed by H 2 reduction. 83 After the heat treatment, more Lewis sites can be exposed owing to the creation of missing-linker defects. Therefore, the obtained defective Pd/UiO-66-NO 2 exhibited an excellent catalytic performance with 98.9% FFR conversion and 95.5% CPO selectivity at 150 °C for 5 h. An array of Pd particles loaded on Cu-MOFs with pure Lewis acidity were prepared for the hydrogenative ring-rearrangement reaction of FFR (Fig.…”

A Comprehensive Review on Metal Catalysts for the Production of Cyclopentanone Derivatives from Furfural and HMF

“…The Fe-containing MOFs showed higher selectivity to CPO than Cr due to the higher oxophilicity. The Zr-MOFs (UiO-66) with Lewis acidity proved to be a good support for Pd for this transformation ( Table 4 , Entry 18) [ 107 ]. The introduction of nitro to the carboxylic acid ligand would further enhance the Lewis acidity on UiO-66-NO 2 .…”

Catalytic Transformation of Biomass-Derived Furfurals to Cyclopentanones and Their Derivatives: A Review

“…High Lewis acidity of the MOF support was responsible for catalyzing the molecular rearrangement reaction under moderate conditions. The catalyst was stable and successfully recycled for four catalytic cycles …”