This study employs an environmentally-friendly method to synthesize MIL-100(Fe),and utilizes a double-solvent impregnation approach to confine Pt nanoparticles within the pores of MIL-100(Fe),subsequent to acidification with HCl and reduction with formaldehyde,a bifunctional catalyst,Pt/MIL-100(Fe),featuring hydrogenation and Lewis acid centers,is prepared.The catalytic performance is evaluated using the selective hydrogenation of cinnamaldehyde(CAL)as a probe reaction.Under optimal conditions(60℃,1 MPa H2),the conversion of CAL reaches 88.3%in 2 h,with a cinnamyl alcohol(COL)selectivity of 84.9%.By comparing the reaction performance of Pt/MIL-100 catalysts with Cr,Al and Fe metal centers,it is revealed that the Fe center favors for the hydrogenation of C=O bonds in both CAL to COL and furfural to furfuryl alcohol.The impact of water content in the reaction system on the selective hydrogenation of CAL is extensively studied.Characterization and static adsorption experiments indicate that removal of free water from the pores of Pt/MIL-100(Fe)facilitates direct enrichment of CAL in the channels,leading to an enhanced conversion.Additionally,removal of coordinated water from the Fe cluster promotes the adsorption of the C=O group of CAL,resulting in an improved selectivity toward COL.After five catalytic cycles under optimal conditions,Pt/MIL-100(Fe)maintains the catalytic performance.Results of powder X-ray diffraction(XRD),transmission electron microscopy(TEM),and low-temperature nitrogen adsorption characterization confirm the stability of the catalyst structure after reaction.
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