Pd-Decorated Magnetic Spinels for Selective Catalytic Reduction of Furfural: Interplay of a Framework-Substituted Transition Metal and Solvent in Selective Reduction

Abstract

The reduction of functional platform chemicals, such as furfural, to industrially important chemicals and fuel requires precise modulation of surface reactivity of the catalyst to obtain the desired reactivity and selectivity. In this study, the selective reduction of furfural (FAL) to furfuryl alcohol (FOL) and tetrahydrofufuryl alcohol (THFA) is achieved by the transition metal interplay in the framework structure of magnetic spinels Fe 3 O 4 and by modulating the reaction medium. Herein, FAL is selectively and quantitatively reduced to FOL in water at very mild reaction conditions over Pd-decorated CuFe 2 O 4 , whereas FAL is selectively converted to THFA in hexane at mild reaction conditions over Pd-decorated NiFe 2 O 4 , using H 2 as an economical reducing agent. The Pd loading, reaction temperature, H 2 pressure, and reaction time are minimized to obtain the best selectivity toward THFA. Different modes of FAL adsorption occur on CuFe 2 O 4 and NiFe 2 O 4 surfaces. Dissociative adsorption of H 2 occurs on Pd sites to form Pd-H species, followed by transfer hydrogenation from Pd-H to FAL adsorbed on spinels, leading to the formation of FOL or THFA. Efficient magnetic recyclability and the hot filtration test show that the catalyst exhibits no significant loss in the activity even after five recycles. Catalysts exhibit very high activity, selectivity, and low activation energy, which are very attractive for academic and industrial points of view.

Pd-Decorated CePO4 Catalyst for the One-Pot, Two-Step Cascade Reaction to Transform Biomass-Derived Furanic Aldehydes into Fuel Intermediates

“…The lower-binding-energy peaks at 335.3 and 340.7 eV correspond to the Pd 0 species, while peaks at higher binding energies of 337.6 and 342.9 eV correspond to the Pd 2+ species present in Pd(3%)/CePO 4 . 41 The ratio of Pd 0 /Pd 2+ in Pd(3%)/ CePO 4 is 2.18. X-ray photoelectron spectroscopy analysis confirms the presence of a higher concentration of Pd 0 species than Pd 2+ species in the material.…”

“…Each of these two peaks shows two different components; therefore, the complete Pd 3d spectrum can be deconvoluted into four peaks located at binding energies of 335.3, 337.6, 340.7, and 342.9 eV (Figure b). The lower-binding-energy peaks at 335.3 and 340.7 eV correspond to the Pd 0 species, while peaks at higher binding energies of 337.6 and 342.9 eV correspond to the Pd 2+ species present in Pd(3%)/CePO 4 . The ratio of Pd 0 /Pd 2+ in Pd(3%)/CePO 4 is 2.18.…”

“…Reduction in surface area and the β-hydride species of Pd(5%)/ CePO 4 can be ascribed to the agglomeration of Pd nanoparticles due to the high Pd content. Similar behavior of Pd nanoparticles is also reported in our previous report for Pd-supported spinel catalysts 41. This can also be due to the low content of the Pd 0 species.…”

Spinel-based catalysts for the biomass valorisation of platform moleculesviaoxidative and reductive transformations

“…Along the same lines, Pd nanoparticles and the CuFe 2 O 4 spinel catalyst, previously used in the hydrogenation of FF to THFA, was also investigated for HMF hydrogenation. 62 The catalyst successfully produced DHMF (>99.5%) as the sole product at 60 °C and 1 MPa H 2 pressure in 2 h (Table 8, entry 5). Similar to FF, the oxygen binds to the Fe atom while the furan ring is perpendicularly adsorbed on the Cu metal through the oxygen atom of the -CvO group via the η 1 (O) mode, facilitating efficient adsorption.…”

“…Recently, an interplay between the transition metal ions in the magnetic spinel framework and solvent modulation for selective hydrogenation was studied. 62 The hydrogenation of FF using Pd nanoparticles decorated on transition metal substituted ferrites using molecular hydrogen was carried out. The hydrogenation of FF using these ferrites showed different performances depending on the solvent used for the reaction.…”