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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]