Aqueous-Phase Hydrogenolysis of Glycerol over Re Promoted Ru Catalysts Encapuslated in Porous Silica Nanoparticles

Abstract

Activity improvement of Ru-based catalysts is needed for efficient production of valuable chemicals from glycerol hydrogenolysis. In this work, a series of Re promoted Ru catalysts encapuslated in porous silica nanoparticles (denoted as Re-Ru@SiO2) were prepared by coating silica onto the surface of chemically reduced Ru-polyvinylpyrrolidone colloids, and were used to catalyze the conversion of glycerol to diols and alcohols in water. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) were used to characterize these nanoparticles. Effects of Ru/Si atomic ratio, Re addition, glycerol and catalyst concentrations, reaction time, temperature, and hydrogen pressure were investigated. Re addition retarded the reduction of ruthenium oxide, but increased the catalyst reactivity for glycerol hydrogenolysis. Due to its greater Ru content, Re-Ru@ SiO2 showed much better activity (reacted at much lower temperature) and more yields of 1,2-propanediol and overall liquid-phase products than Re-Ru/SiO2 (prepared by conventional impregnation method) reported before. The rate of glycerol disappearance exhibited first-order dependence on glycerol concentration and hydrogen pressure, with an activation energy of 107.8 kJ/mol. The rate constant increased linearly with increasing Ru/Si atomic ratio and catalyst amount. The yield of overall liquid-phase products correlated well with glycerol conversion.

Catalytic Approaches to Monomers for Polymers Based on Renewables

“…1,2-Propanediol (D2). Propylene glycol (D2), which is used to modify crystallinity in polyesters such as PET, can be obtained by hydrogenolysis from glycerol at around 200 °C using heterogeneous catalysts such as Ru/MgAlO 4 , 139 Re-Ru/ SiO 2 , 140 Pt-H 4 SiW 12 O 40 , 141 Cu-Zn/MgAlO 4 , 142 or Cu/MgO (Scheme 20). 143 Interestingly, high selectivities of 90−94% at full conversion can be obtained using Cu-Zn/MgAlO 4 in combination with basic additives or on Cu/MgO using water as solvent.…”

Crude Glycerol Hydrogenolysis to Bio-Propylene Glycol: Effect of Its Impurities on Activity, Selectivity and Stability

“…In addition, cleavage reactions of C-C bonds in the glycerol molecule generate side products, such as methanol (MeOH) and ethylene glycol (EG). The consequent hydrogenolysis of 1,2-PG and EG produces terminal It has been reported that catalytic supports play an important role in the formation of AcOH due to their acid-base properties, while metallic phases based on Ru [6], Pt [7], Pd [8], Cu [9][10][11] and Ni [12] intervene in the formation of 1,2-PG through AcOH hydrogenation.…”

“…In Equation (1), coefficients α and β are the partial orders of reaction with respect to glycerol and H2, respectively. It has been reported that catalytic supports play an important role in the formation of AcOH due to their acid-base properties, while metallic phases based on Ru [6], Pt [7], Pd [8], Cu [9][10][11] and Ni [12] intervene in the formation of 1,2-PG through AcOH hydrogenation.…”

On the effect of Alkaline Earth Metal Cations in the Hydrogenolysis of Glycerol over Pt/C – an Experimental and Theoretical Study

“…Apart from a few exceptions, mainly heterogeneous catalysts are used for the hydrogenolysis of GLY to PG. [10][11][12][13] The employed catalysts are typically based on the noble metals Ru/Re, [14] Pd [15][16] and Pt [17][18] or the non-noble metals Ni [19][20] and Cu. [21] Next to the metal catalyst, a basic or acidic co-catalyst is added to enable the reaction.…”