Unravelling the Mechanism of Glycerol Hydrogenolysis over Rhodium Catalyst through Combined Experimental-Theoretical Investigations

BIOVERT+FAU:CPIWe report herein a detailed and accurate study of the mechanism of rhodium-catalysed conversion of glycerol into 1,2-propanediol and lactic acid. The first step of the reaction is particularly debated, as it can be either dehydration or dehydrogenation. It is expected that these elementary reactions can be influenced by pH variations and by the nature of the gas phase. These parameters were consequently investigated experimentally. On the other hand, there was a lack of knowledge about the behaviour of glycerol at the surface of the metallic catalyst. A theoretical approach on a model Rh(111) surface was thus implemented in the framework of density functional theory (DFT) to describe the above-mentioned elementary reactions and to calculate the corresponding transition states. The combination of experiment and theory shows that the dehydrogenation into glyceraldehyde is the first step for the glycerol transformation on the Rh/C catalyst in basic media under He or H(2) atmosphere

Rotational integral geometry of tensor valuations

We derive a new rotational Crofton formula for Minkowski tensors. In special cases, this formula gives (1) the rotational average of Minkowski tensors defined on linear subspaces and (2) the functional defined on linear subspaces with rotational average equal to a Minkowski tensor. Earlier results obtained for intrinsic volumes appear now as special cases

Heterogeneous Transformation of glycerol to lactic acid

International @ BIOVERT+MBE:LDJ:CPIInternational audienceNon

From glycerol to lactic acid by heterogeneous catalysis.

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On the role of the atmosphere in the catalytic glycerol transformation over iridium-based catalysts

EAU:BIOVERT+FAU:SNO:GAU:LDJ:CP

From glycerol to lactic acid under inert conditions in the presence of platinum-based catalysts: The influence of support

SSCI-VIDE+CDFA+JFT:NVI:FAU:MBE:LDJ:CPIInternational audienceIn this work, it was shown that glycerol (Gly) can be effectively converted to lactic acid (LA) under inert atmosphere using a Pt/ZrO2 catalyst. Starting from pure glycerol, at 180 degrees C and under a He pressure of 30 bar, we were able to achieve up to 80% yield of LA after a reaction time of 8 h. The catalysts performance of Pt/TiO2, Pt/C and Pt/ZrO2 were compared showing that using Pt/ZrO2 high conversion and stable LA selectivity were achieved during all the process. Further, using Pt/ZrO2 the LA selectivity was less sensitive to the nature of the reaction atmosphere while using either H-2 or He. While using crude Gly (85% purity), a lower reaction rate was obtained in the presence of Pt/ZrO2, however high selectivity to LA (similar to 80%) was maintained. (C) 2014 Elsevier B.V. All rights reserved

Glycerol conversion to lactic acid in the presence of platinum based catalysts.

International @ BIOVERT+JFT:MBE:LDJ:CPIInternational audienceIn the last decade, lactic acid (LA) became an important feedstock, with an annual production of 120,000 tonnes. This importance comes from its use in: i) food-industry: as a food acidulant or as a bacterial spoilage inhibitor and (ii) as a new raw material to produce biodegradable thermoplastics. Nowadays, the LA production is mainly ensured by a saccharide fermentation route; nevertheless, this process still needs improvement. We have previously shown that lactic acid can be obtained from glycerol in the presence of iridium or rhodium-based catalysts. In this present work we introduce the LA obtainment from glycerol (Gly) in the presence of platinum (Pt) - based catalysts

Catalytic transformation of glycerol on several metal systems supported on ZnO

BIOVERT+FAU:CPIDifferent metal systems consisting in platinum supported on several reducible supports (5% by weight) were synthesized through the deposition-precipitation technique and tested for glycerol hydrogenolysis. Interestingly, supports exhibiting the highest conversions were those with the greatest strong metal-support interaction (SMSI) effect, ZnO and SnO2, eventually forming alloys (Pt-Zn and Pt-Sn, respectively). ZnO was subsequently selected for further studies as support for Rh, Pt, Pd and Au and the resulting solids were tested again for glycerol catalytic transformation under reductive or inert atmosphere at 453 K. Under similar reaction conditions, glycerol conversion order followed the sequence Pt > Rh >> Pd >> Au. Moreover, the solids reduced at 473 K were more active than those activated at 673 K, which evidences the detrimental effect of the increase in metal particle size and/or alloy formation on the catalytic performance. Quite high yields to lactic acid were achieved in a basic medium (e. g. 68% for Rh/ZnO-473 under H-2) whereas yield to 1,2-PDO was more modest (26% for Rh/ZnO-673 under similar reaction conditions). (C) 2012 Elsevier B. V. All rights reserved

Heterogeneous Transformation of Glycerol to Lactic Acid

BIOVERT+FAU:LDJ:CPISignificant yields of lactic acid (LA) are obtained during the treatment of glycerol solution under inert gas with supported metallic catalysts under basic conditions. The nature of the atmosphere and the metal affected the activity and the selectivity of the reaction. Iridium-based catalysts are efficient for LA synthesis

Aqueous-phase selective hydrogenolysis of xylitol in a trickle-bed reactor using a carbon supported-Ru catalyst

Internationa