ABSTRACT
High (≥95 % C) yields of n-hexane and n-pentane were obtained by hydrogenolysis of aqueous sorbitol and xylitol, respectively, at 413-443 K by using the Ir-ReOx /SiO2 catalyst combined with H-ZSM-5 as a cocatalyst and n-dodecane as a cosolvent. The direct production of n-hexane from glucose or cellobiose can be achieved by using the same system. The catalyst can be reused simply by the removal of the n-dodecane phase, which contains the product alkane, and the addition of fresh n-dodecane and substrate.
Subject(s)
Alkanes/chemistry , Carbohydrates/chemistry , Sugar Alcohols/chemistry , Catalysis , Iridium/chemistry , Silicon Dioxide/chemistry , Zeolites/chemistryABSTRACT
Production of 1,2-propanediol (1,2-PDO) from glycerol hydrogenolysis was carried out in bio-ethanol solvent over small amount of Rh-promoted Cu/solid-base catalysts prepared via layered double hydroxide precursors. It was found that glycerol hydrogenolysis proceeded easily on Rh-Cu/solid-base catalysts than separated Rh and Cu/solid-base. The conversion of glycerol and selectivity to 1,2-PDO over Rh(0.02)Cu(0.4)/Mg(5.6)Al(1.98)O(8.57) reached 91.0% and 98.7%, respectively, at 2.0 MPa H(2), 180 °C. And this catalyst was stable in five consecutive hydrogenolysis tests in ethanol.
Subject(s)
Biofuels , Ethanol/chemistry , Glycerol/chemistry , Propylene Glycols/chemical synthesis , Propylene Glycols/isolation & purification , Solvents/chemistry , CatalysisABSTRACT
Hydrogenolysis of biodiesel derived glycerol to 1,2-propanediol (1,2-PDO) has attracted much attention in recent years. In this work, glycerol hydrogenolysis to 1,2-PDO was performed over CuO/MgO catalysts prepared by impregnation and coprecipitation at 180 degrees C and 3.0 MPa H(2). It was found that the Cu(15)/MgO catalyst prepared by coprecipitation had the best activity. The conversion of glycerol and the selectivity of 1,2-PDO over Cu(15)/MgO reached 72.0% and 97.6%, respectively. And the conversion of glycerol was further increased to 82.0% when small amount of NaOH was added in the reaction mixture. Those highly active catalysts were characterized by X-ray diffraction, transmission electron microscopy, N(2)-adsorption and temperature-programmed reduction with H(2). Characterization results revealed that the activity of the prepared catalysts depended strongly on the particle sizes of both Cu and MgO. Catalysts that have smaller sized Cu and MgO particles are more active for glycerol hydrogenolysis.
