Ken Griffin

Oxidation of glycerol using supported Pt, Pd and Au catalysts

The oxidation of aqueous solutions of glycerol is described and discussed for Pd, Pt and Au nanoparticles supported on graphite and activated carbon. The oxidation in a batch reactor at 60 °C and 1 bar pressure using air as oxidant was initially investigated. Under these conditions, supported Pd and Pt catalysts give some selectivity to glyceric acid, but the main reaction products are considered to be non-desired C1 by-products, e.g. CO2, HCHO and HCOOH. In addition, under these conditions, supported Au catalysts were totally inactive. Using an autoclave with pure oxygen at 3 bar pressure gave a significant improvement in reactivity and, for Pt and Au catalysts, the formation of C1 by-products was eliminated when NaOH was added. In particular, it was noted that, in the absence of NaOH, the Au/C catalyst was inactive. For 1 wt.% Au/graphite or activated carbon, 100% selectivity to glyceric acid at high conversion was readily achieved. The role of the base is discussed and it is proposed that the base aids the initial dehydrogenation via H-abstraction of one of the primary OH groups of glycerol and, in this way, the rate limiting step in the oxidation process is overcome.

Selective oxidation of glycerol to glyceric acid using a gold catalyst in aqueous sodium hydroxide

Glycerol is oxidised to glyceric acid with 100% selectivity using either 1% Au/charcoal or 1% Au/graphite catalyst under mild reaction conditions (60 degrees C, 3 h, water as solvent).

Selective catalytic reduction of O2 with excess H2 in the presence of C2H4 or C3H6

The selective reduction of molecular oxygen with excess H(2) in the presence of alkenes was achieved successfully for the first time: silver supported on alumina catalysts exhibited full conversion of O(2) at temperature as low as 50 degrees C, while the conversion of ethene or propene remained essentially zero up to 250 degrees C.