Preparation of Pd/MOF and Ru/MOF Catalysts and Catalytic Performance for Hydrogenation and Cross-coupling Reactions

Abstract

Metal-organic framework compound consisting of terephthalic acid and chromium cation (TPA–Cr) was prepared by the hydrothermal method and characterized by XRD, N₂ adsorption-desoprtion isotherm, TGA-DTA and TEM. The prepared TPA–Cr was crystalline and phase-pure. Noble metal was supported on TPA–Cr by the conventional impregnation method. The specific Pd salt and solvent for impregnation significantly influenced the location of Pd. With [Pd(NH₃)₄](NO₃)₂ dissolved in water, Pd was located in the micropores of TPA–Cr, whereas with PdCl₂ dissolved in water or methanol, Pd was located on the external surface of TPA–Cr. Hydrogenation of cinnamaldehyde and crotonaldehyde, and cross-coupling between aryl bromides and phenylboronic acid were studied using Pd/TPA–Cr and Ru/TPA–Cr prepared as above. Hydrogenation of the two model aldehydes occurred in the micro- and meso-pores of TPA–Cr whereas cross-coupling reaction of bulkier compounds occurred mostly on the external surface of TPA–Cr.