Ratio-controlled synthesis of phyllosilicate-like materials as precursors for highly efficient catalysis of the formyl group
The design and development of heterogeneous catalysts is very critical for the synthesis of various chemicals and fuels derived from superfluous biomass. The synthesis of biofuel 2-methylfuran typically derives from the conversion of the formyl group of biomass-derived furfural, because this process is very valuable in terms of the amelioration and remission of the environment and energy crisis. Herein, we designed a series of bifunctional catalysts formed in line with the spatial restriction strategy by anchoring copper nanoparticles (Cu NPs) on phyllosilicate-like structures to enhance copper dispersion and provide properly assembled Lewis acid sites to promote the hydrogenation and hydrogenolysis of the formyl group in furfural, and first applied them to the conversion of the formyl group with high efficiency. However, the modulation of the Cu–Si molar ratio is extremely critical to the possible reduction of metal consumption, full exploitation of the prerequisite metal sites and great improvement of activity. In this work, the catalyst with a Cu–Si molar ratio (actual value = 0.33) lower than that of the industrial catalyst (theoretical value = 1.0) exhibited higher yields of the intermediate furfuryl alcohol (yield = 83.4%) and the desired product 2-methylfuran (yield = 95.5%). More importantly, with the continuous increase of the Cu–Si molar ratio, it is discovered that Cu dispersion regularly decreased and the size of the Cu NPs sequentially increased, and the change of assembled Lewis acid sites surprisingly kept pace with the integrity of the layered structure, as revealed by a series of detailed characterization studies.