Search

The as-prepared Cu/NC@SBA-15 composites are highly active for the hydrogenation of levulinic acid to γ-valerolactone, giving a maximum yield as high as 92 % at 140 ºC in a continuous-flow fixed-bed reactor. [Display omitted] • Fine Cu clusters anchored on g-C 3 N 4 nanoconfined into SBA-15 were developed. • The defect N sites were crucial to anchor and disperse Cu nanoclusters. • An excellent GVL yield of 92 % was achieved, comparable to that of the Ru/AC. • DFT revealed that the reaction barrier of the nanoconfined Cu clusters was reduced. • The anchoring strategy prevents the sintering of Cu clusters during the reaction. The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is a common reaction that is critical to biomass transformation. However, it is a great challenge to employ non-noble metal catalysts in realizing highly effective conversion from LA to GVL. Herein, we report an efficient strategy for anchoring highly active copper nanocluster catalysts on the defect sites of graphitic carbon nitride (g-C 3 N 4) and dispersing in mesoporous silica (SBA-15). The combination of g-C 3 N 4 and SBA-15 stabilized the copper clusters, leading to a high GVL yield of 92 % and excellent stability in 100 h. This result is comparable to that of the Ru/AC catalyst but much more economically favorable. Density functional theory calculations revealed that the reaction barrier of the new catalyst was reduced from 1.93 to 1.12 eV compared with those of unconfined copper particles. This research provides a simple anchoring strategy for constructing highly active and inexpensive copper nanocluster catalysts. [ABSTRACT FROM AUTHOR]

Atomically dispersed cluster catalysts own versatile applications in biomass valorization, while the controllable assembly and microenvironmental regulation remain a crucial challenge. Herein, Co clusters assembled via nanosized ZIF-67 sprouted from Co-Al layered double hydroxide nanoflowers were applied for selective hydrogenation of furfural (FAL). The pyrolysis temperature can tune the microstructures and acid properties of the catalyst, which accounts for the hydrogenation of FAL to furfuryl alcohol (FOL), 2-methylfuran (2-MF), and tetrahydrofurfuryl alcohol (THFOL) with yield of 99.1 %, 96.7 %, and 82.3 %, respectively. The Co clusters favor C O bond adsorption via bridging-type adsorption mode while suppressing the furan ring adsorption. Moreover, ultra-dispersed Co clusters facilitate the cleavage of C-OH bonds in FOL intermediate, leading to a high 2-MF yield. As the pyrolysis temperature increase, the formed Co nanoparticles are conducive to the parallel adsorption of FAL, resulting in the production of THFOL. This work affords a multi-functional catalyst in catalytic biomass upgrading. [Display omitted] • The ultrafine Co clusters embedded in carbon matrix were developed. • The migration of Co on LDH surface will expose a large number of Lewis acid sites, which facilitate the activation of C=O band. • The microstructure and acid-base properties can be adjusted by varying the pyrolysis conditions. • The relationship between the adsorption mode of substrate and the hydrogenation pathway was thoroughly explored. [ABSTRACT FROM AUTHOR]