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.