Hydrogenolysis of glycerol over a highly active CuO/ZnOcatalyst prepared by an oxalate gel method: influence of solvent and reaction temperature on catalyst deactivation

Abstract

The hydrogenolysis of glycerol was performed in an autoclave at temperatures between 190 and 225 • C and at a H 2 pressure of 5 MPa over a CuO/ZnO catalyst prepared by an oxalate gel (OG) method. Compared to a CuO/ZnO catalyst prepared by coprecipitation, much higher conversions of glycerol and space-time yields up to 9.8 g propylene glycol g Cu -1 h -1 are achieved with CuO/ZnO-OG, whereas both catalysts produced propylene glycol with selectivities of about 90%. Additionally, the influence of the temperature and the solvent was examined. Compared to a conversion of glycerol of only 5% in an aqueous glycerol solution, the use of 1,2-butanediol as a solvent leads to a high conversion of 55%. Moreover, experiments were carried out in pure glycerol and from transmission electron microscopy images of fresh and spent catalysts, it was obvious that the morphology of the catalyst changed during the reaction. By X-ray diffraction and N 2 O chemisorption, it was proved that a tremendous loss of copper surface area occurred during the hydrogenolysis of glycerol. Taking together the influence of the solvent on the conversion of glycerol and the results of the catalyst characterization, it can be concluded that water, as an unavoidable by-product of the reaction, is responsible for a strong deactivation of the catalyst.

Glycerol Hydrogenolysis over Co Catalysts Derived from a Layered Double Hydroxide Precursor

“…However, the sintering of the metal particles during the course of the reaction often resulted in catalyst deactivation [10][11][12][13]. For example, the sintering of Cu particles in the Cu/ZnO catalysts reduced the conversion of glycerol from 46 to 10% upon reuse [10]. A similar deactivation pattern was observed for Cu/Al 2 O 3 catalysts [11].…”

“…Until now, supported Cu [3], Co [4], Ni [5], Ru [6], Pt [7], Rh [8] and Ir [9] catalysts have been reported to be active towards glycerol hydrogenolysis. However, the sintering of the metal particles during the course of the reaction often resulted in catalyst deactivation [10][11][12][13]. For example, the sintering of Cu particles in the Cu/ZnO catalysts reduced the conversion of glycerol from 46 to 10% upon reuse [10].…”

Development of cerium promoted copper–magnesium catalysts for biomass valorization: Selective hydrogenolysis of bioglycerol

“…to 65% with increased reaction temperature from 433 to 493 K, respectively. On the other hand, there is no significant effect of the temperature on the selectivity of 1,2-PDO up to 473 K. After 473 K, a slight decrease in the selectivity of 1,2-PDO was observed, whichmight be due to the easy C-C bond cleavage of the glycerol with acceleration of the reaction rate at high reaction temperatures [62,63]. The apparent activation energies evaluated from the Arrhenius plot were found to be ~58.3 and 26.6 kJ mol -1 for the Cu/Mg and Cu/Ce3/Mg catalysts, respectively (Fig.…”

Efficient and selective conversion of glycidol to 1,2-propanediol over Pd/C catalyst

“…However this situation has put on the market a new cheap raw material and a great number of new uses of glycerol has been proposed [2,3]. The production of propanediols (1,2 propanediol (1,2-PD) and 1,3 propanediol (1,3-PD)) by hydrogenolysis of glycerol has received particular attention [4][5][6][7][8][9]. The reaction of hydrogenolysis of glycerol is characterized by the necessity of high hydrogen pressure , high reaction temperature (400-500 K), and also by problems related with the selectivity (1,2-PD, 1,3-PD, 1 Propanol, 2 Propanol, ethylene glycol, ethanol can be formed in the hydrogenolysis reaction) [10,11].…”