Improving selective hydrogenation of carbonyls bond in α, β-unsaturated aldehydes over Pt nanoparticles encaged within the amines-functionalized MIL-101-NH₂

The high selectivity in the hydrogenation reactions of α, β-unsaturated aldehydes is always a demanding task. Precious Pt-based catalysts play a pivotal role in selective catalytic hydrogenation of α, β-unsaturated aldehydes, but controlling the selectivity is still a great challenge. Herein, the Pt nanoparticles were encaged within the mesopores of amines (–NH₂) functionalized MOFs via polyol reduction method as an efficient approach to enhance the selectivity of desired carbonyls bond reduction. The as-prepared 3-Pt/MOF-NH₂(x) catalysts retained the inherent properties of MOF-NH₂(x) supports such as crystallinity, surface area, pore texture, and surface acidity. Remarkably, the amines modified MOFs supported Pt-based catalysts (3-Pt/MOF-NH2(x)) improved the selective hydrogenation of carbonyls (C[dbnd]O) bond in cinnamaldehyde (CAL) and Furfural (FFL) with a higher selectivity (≥80 %) under mild conditions as compared to other reported catalysts. The improved catalytic performance for the selective hydrogenation of carbonyls (C[dbnd]O) bond is credited to the nitrogen (N) heteroatom of the amines group existing in the skeleton of MOFs and somewhat to the steric effect induced by mesopores of MOFs. The N heteroatom not only helps in the high uniform dispersion and stabilization of small-sized Pt nanoparticles (≈2nm) but also adjust the electron movement (electronic density) via synergistic effect resulting from the N to the vacant d-orbital of active Pt nanoparticles confined within MOFs, leading to more new interfacial electrophilic and nucleophilic sites, which are beneficial for selective hydrogenation of C[dbnd]O bond. Besides, the steric effect induced by mesopores of MOFs, encaging Pt nanoparticles, can also enhance the selective adsorption of the C[dbnd]O bond to interact with the catalyst active sites, resulting in higher selective hydrogenation of C[dbnd]O bond.