from first principles PP-I-1

OP-IV-5Selective Oxidation of Glycerol Using Au/ZrO 2 as CatalystLiu S.-S., Sun K.-Q., Liang Yu., Xu B.-Q.Innovative Catalysis Program, Department of Chemistry, Tsinghua University,Beijing 100084, Chinabqxu@mail.tsinghua.edu.cnWe present here a comprehensive study on the catalytic performance of Au/ZrO 2 [1,2] forglycerol (GL) oxidation in aqueous solution containing varying amounts of NaOH and discussthe reaction mechanism on the basis of detailed quantitative analyses of the productselectivity in response to the reaction variables including temperature (0−80 ºC), molarNaOH/GL ratio (0−15), oxygen pressure (PO 2 = 0.1−2.5 MPa) and duration of reaction.A nanocomposite 1 wt% Au/ZrO 2 catalyst (Au: 2−4 nm, ZrO 2 : 6−10 nm) was prepared [3] forthis study using a batch reactor. We confirmed no reaction in the absence of the base(NaOH/GL = 0) under the most commonly used temperature (60 ºC) and PO 2 (1.0 MPa).Increasing the ratio up to NaOH/GL= 10 resulted in increases in both the conversion of GLand the selectivity for glyceric acid (GLA) though the increase in the GLA selectivity wasless significant (57−60% on carbon calibration) at NaOH/GL= 2−10. However, a furtherincrease of the ratio to NaOH/GL = 15 even led to much lower GL conversion. Formation oflactic acid (LA) kept on increasing at NaOH/GL > 0.1 though it was not detected in thereaction with lower NaOH/GL ratios. Significant amounts of the non-C3 products, glycolicacid (GCA), formic acid (FA) and acetic acid (AC), were formed at NaOH/GL 0.1, they alldecreased in the reaction with higher NaOH/GL ratios. The oxygen pressure (PO 2 ) had aremarkable effect on GL reactivity and product distribution. The selectivity for LA was ashigh as 58% at PO 2 = 0.1 MPa (60 ºC, NaOH/GL= 2) with a GL conversion of ca. 3% andGLA selectivity of 29%. The LA selectivity decreased to 21% but the GLA selectivityincreased to 54% at PO 2 = 0.2 MPa. The GL conversion was retained upon raising the pressureup to PO 2 = 2.5 MPa but the GLA selectivity became stabilized at 60−63% at PO 2 1 MPa.The GCA, FA and AC products varied in the opposite to LA.On lowering the reaction temperature to 0−20 ºC, GLA, FA, GCA and AC were detected asthe products when the GL conversion was < 5%; the C1 product FA appeared as the mainproduct (> 40%) at 0 ºC, far more than the C2 product (GCA + AC: < 20%), when less than1% GL was converted. The selectivity for GLA increased while that for GCA and FAdecreased when the temperature was increased from 20 to 80 ºC; LA was not formed below81