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.

Guidelines to Achieving High Selectivity for the Hydrogenation of α,β-Unsaturated Aldehydes with Bimetallic and Dilute Alloy Catalysts: A Review

“…Aggregated data reporting the selectivity to the unsaturated alcohol (UOL) as a function of the unsaturated aldehyde (UAL) conversion, illustrating the effects of a secondary metal on: (a) Pt and Pt-rich bimetallics for the hydrogenation of crotonaldehyde, ,,,,,,,,, cinnamaldehyde, ,,,,− ,,− ,− furfural, ,,,,,,− and citral . (b) Ru and Ru-rich bimetallics for the hydrogenation of crotonaldehyde, ,− ,,− cinnamaldehyde, ,,,,, furfural, and citral. , (c) Ir and Ir-rich bimetallics for the hydrogenation of crotonaldehyde ,,,,, and cinnamaldehyde. ,,, (d) Rh and Rh-rich bimetallics for the hydrogenation of crotonaldehyde ,, and citral . (e) Pd and Pd-rich bimetallics for the hydrogenation of cinnamaldehyde ,,− and furfural .…”

“…Monometallic Ru catalysts have generally shown low selectivity to the unsaturated alcohols and a propensity for deactivation in the hydrogenation of crotonaldehyde, ,− ,,,, cinnamaldehyde, ,,,, and citral , (Figure b). The only exception is crotonaldehyde hydrogenation on Ru/ZnO containing chlorine residues from the preparation method, but this monometallic catalyst was outperformed by an IrRu alloy catalyst (see below) .…”

“…Monometallic Ru catalysts have generally shown low selectivity to the unsaturated alcohols and a propensity for deactivation in the hydrogenation of crotonaldehyde, 132,[140][141][142]214,228,229,231 cinnamaldehyde, 101,141,214,228,232 and citral 141,234 (Fig. 9b).…”

“…The nature of the reactant strongly influences the degree of selectivity to the unsaturated alcohol 85,100,116,133,134,142,147,214,222,223 cinnamaldehyde, 86,100,133,134,147−149,155,157−159,211−219 furfural, 133,134,147,213,220,221,224−227 and citral. 221 (b) Ru and Ru-rich bimetallics for the hydrogenation of crotonaldehyde, 132,140−142,214,228−231 cinnamaldehyde, 101,141,156,214,228,232 furfural, 233 and citral. 141,234 (c) Ir and Ir-rich bimetallics for the hydrogenation of crotonaldehyde 142,145,146,229,235,236 and cinnamaldehyde.…”

“…Aggregated data reporting the selectivity to the unsaturated alcohol (UOL) as a function of the unsaturated aldehyde (UAL) conversion, illustrating the effects of a secondary metal on: (a) Pt and Pt-rich bimetallics for the hydrogenation of crotonaldehyde,85,100,116,133,134,142,147,214,222,223 cinnamaldehyde,86,100,133,134,147−149,155,157−159,211−219 furfural,133,134,147,213,220,221,224−227 and citral 221. (b) Ru and Ru-rich bimetallics for the hydrogenation of crotonaldehyde, 132,140−142,214,228−231 cinnamaldehyde,101,141,156,214,228,232 furfural,233 and citral 141,234. (c) Ir and Ir-rich bimetallics for the hydrogenation of crotonaldehyde142,145,146,229,235,236 and cinnamaldehyde 142,153,237,238.…”