Zeolite-Encapsulated Cu Nanoparticles for the Selective Hydrogenation of Furfural to Furfuryl Alcohol

Abstract

Catalytic hydrogenation of furfural (FFL) to furfuryl alcohol (FAL) is one of the pivotal reactions for biomass valorization. Herein, welldefined Cu nanoparticles of ∼1.8 nm encapsulated within titanium silicalite-1 (TS-1) have been successfully prepared by an in situ encapsulation approach, which possesses significant advantages in metal dispersion and uniformity compared to the traditional wet impregnation method. After a Na ionexchange process for modulation of the zeolite microenvironment, the obtained Na−Cu@TS-1 catalyst affords an enhanced activity and selectivity in the selective hydrogenation of FFL into FAL, with a FFL conversion of 93.0% and a FAL selectivity of 98.1% at 110 °C, 10 bar H 2 , after a reaction time of 2 h. A turnover frequency value of 55.2 h −1 has been achieved, reflecting some of the highest activity for Cu-based heterogeneous catalysts under similar conditions. Comprehensive characterization studies reveal that the confined environment of the zeolite could not only provide the spatial restriction for metal particles but also induce an electronic interaction between encapsulated Cu nanoparticles and Ti species in Na−Cu@TS-1, which both lead to effective suppression of the metal aggregation and leaching during catalysis. Na species, added by the ion exchange, not only mediate the acid/basic property of the zeolite for suppressing the side reactions but also modulate the encapsulated Cu species into an electronic-rich state, facilitating the FFL hydrogenation. Deactivation of Na−Cu@TS-1 is primarily caused by Na leaching into the liquid phase, but activity can be almost restored after a Na readdition process.

High Performing and Stable Cu/NiAlOx Catalysts for the Continuous Catalytic Conversion of Ethanol into Butanol

“…Cu LMM X‐ray‐induced Auger electron spectroscopy (XAES) was carried out for further discrimination and quantification of the Cu 0 and Cu + species (Figure 6b). The featured peaks located at 918.6 and 914.8 eV are ascribed to Cu 0 and Cu + , respectively [44,45] . Combined with XPS and ICP‐AES results, the Cu species in different catalysts can be quantified.…”

“…The featured peaks located at 918.6 and 914.8 eV are ascribed to Cu 0 and Cu + , respectively. [44,45] Combined with XPS and ICP-AES results, the Cu species in different catalysts can be quantified. The related amounts of each species are shown in Figure 6c.…”

Design of Heterogeneous Catalysts for the Conversion of Furfural to C5 Derivatives: A Brief Review

“…The effects of inhibition of catalytic activity, the drop in selectivity due to the presence of water, and the effect of different concentrations of 2propanol were also discussed. Cao et al [30] studied how alkaline species improved the catalytic performance of Cu nanoparticles encapsulated in TS-1 zeolites. The sample Na-Cu@TS-1, prepared following the in situ encapsulation method, presented excellent catalytic performance.…”

Zeolite confinement-catalyzed cleavage of C–O/C–C bonds in biomass

“…23b). 202 More strikingly, in phenol hydrodeoxygenation, the encapsulation of Ru in X zeolite (Ru@NaX) puts it in an electron-deficient state, which promotes the adsorption of hydrogen and improves catalytic activity. In addition, the strong adsorption of cyclohexanone by the X zeolite framework inhibits further hydrogenation and improves catalytic selectivity, and these two aspects together lead to higher selectivity for cyclohexanone in phenol hydrogenation 203 (Fig.…”