Remarkable Enhancement in Hydrogenation Ability by Phosphidation of Ruthenium: Specific Surface Structure Having Unique Ru Ensembles

Abstract

A series of transition metals and metal phosphides supported on silica (M/SiO2 and M x P y /SiO2, M = Pt, Pd, Ir, Rh, Ru, Ni, and Co) were prepared and tested as catalysts for hydrogenation of toluene as a hydrogen carrier. Catalytic activities were reduced greatly by phosphidation of noble metals, such as Pt, Pd, Ir, and Rh. Catalytic activity of Ru, however, showed a remarkable increase in turnover frequency26 times higher than that of bare Ru. Ru2P/SiO2 with a much lower cost exhibited a catalytic performance comparable with those of other platinum group metals. A combination of kinetic, infrared, and computational studies revealed that (1) strong adsorption of toluene on Ru2P promoted hydrogenation and (2) a specific surface structure of Ru2P having large ensembles of electron-deficient Ru allowed the strong adsorption.

Highly selective conversion of phenol to cyclohexanol over Ru/Nb2O5-nC18PA catalysts with increased acidity in a biphasic system under mild conditions

“…Compared with electron-rich sites, benzene rings may preferentially adsorb on electron-deficient metal sites, which is conducive to the hydrogenation of benzene rings in phenol. 42,43 3.1.3 FTIR. The Fourier transform infrared (FTIR) spectra are shown in Fig.…”

Geometric and electronic effects on the performance of a bifunctional Ru2P catalyst in the hydrogenation and acceptorless dehydrogenation of N-heteroarenes

“…The synthesis of Ru2P/AC [27] is shown in Scheme 1. Specifically, 1 mL of an aqueous solution of RuCl3 (Ru 3+ : 10 mg/mL) and (AC 500 mg) was added to 50 mL of deionized water, and the mixture was stirred vigorously overnight at room temperature.…”

“…To further verify the composition of the catalyst, X-ray diffraction (XRD) investigations were performed; however, no peaks corresponding to Ru2P were found (Fig. S5) due to the low loading of these elements on the composites [27].…”

“…Unfortunately, their poor reusability and strict reaction conditions made Ru-based catalysts not very good hydrogenation catalysts [22]. The incorporation of foreign atoms at the interstitial sites [23], such as transition metal carbides [24][25][26] and transition metal phosphides [27][28][29][30], might induce different geometric and electronic properties [31], which could regulate the reaction and desorption barriers of the substrate on the surface of the catalyst [32]. Herein, we demonstrated that ruthenium phosphide NPs supported on activated carbon (Ru2P/AC) could be employed as an efficient bifunctional catalyst for direct reversible transformations between unsaturated and saturated N-heterocycles.…”

Pt/TiO2 Catalyzed Hydrogenation of Benzoic Acid with Unprecedented High Activity

“…Carboxylates tend to strongly adsorb on metal surface, which signi cantly deteriorates the catalytic activity through so-called "poison effects" [19]. In contrast, the adsorption of aromatic ring of BA on metal surface is weak considering that the electron de cient phenyl ring does not easily bind to the surface unoccupied d-metal orbitals via π-bonds [20,21]. This may be the reason that most metal NPs showed relatively low activity in BA hydrogenation.…”