C. Lahousse

Activity of manganese dioxides towards VOC total oxidation in relation with their crystallographic characteristics

This paper describes the catalytic activity of various forms of manganese dioxides towards volatile organic compounds deep oxidation. Important differences in activity are evidenced for very closely related structures; the most active sample is a high surface area nsutite. A parallel is drawn between the findings in the literature of battery applications and the catalytic activity results. The superior activity of nsutite is attributed to a different oxygen coordination and to the clustering of cationic vacancies in the bulk which improves electronic and protonic conductivity.

Characterisation of a gamma-MnO2 catalyst used in VOC abatement

This study presents the results of a comprehensive characterisation of a very efficient VOC abatement catalyst. The changes suffered by a γ-MnO 2 catalyst during VOC oxidation are determined and their impact on the catalytic activity is discussed. Sintering and partial reduction are detected. But they respectively have only a limited and no effect on the stability of the catalytic activity. Conversely, water vapour adsorption appears to cause very long (12h) stabilisation delays.

Preparation of Pd on Carbon Black by Deposition-precipitation: Study of the Effect of the Support Functionalisation

This work provides the comparison of palladium deposition-precipitation and ion exchange on functionalised or non functionalised carbon blacks or TiO2. Results show that functionalisation is mandatory for ion exchange, but that active carbon black supported noble metal catalysts can be prepared without functionalisation using deposition-precipitation.

Optimized conditions for the preparation of Pt supported catalysts by deposition-precipitation

Abstract The deposition-precipitation of platinum was investigated using two different platinum precursors: chloroplatinic acid and ammonium tetrachloroplatinate. While H 2 PtCl 6 did not allow a deposition-precipitation of platinum, a high deposition of platinum could be obtained using (NH 4 ) 2 PtCl 4 in defined conditions.

Influence of the impregnation order of molybdenum and cobalt in carbon supported catalysts for hydrodeoxygenation reactions

This work concerns the role of the impregnation order of molybdenum and cobalt in carbon supported catalysts. Four activated carbons have been used as supports and the effect of the impregnation order (either cobalt or molybdenum at first) has been considered. The samples were characterized by N-2 physisorption, XPS and SEM. The sulfided catalysts have been tested in hydrodeoxygenation, using a model mixture containing: 4-methylacetophenone, ethyldecanoate and guaiacol. Both series of samples exhibit a low dispersion of the active phase, but CoMo is more uniformly distributed than MoCo. This result was interpreted to be consequence of the position occupied by the metal impregnated at first and of the strong interactions existing between cobalt and molybdenum. In the samples containing only one metal, cobalt is mainly impregnated at the exterior of the grains, while molybdenum is impregnated at the interior of the grains, causing micropore blocking. When the second metal is added, cobalt seems to bring about the remobilization of molybdenum outside the grains in CoMo catalysts and the formation of molybdenum oxide on the external grain surface in MoCo. Concerning catalytic activity, CoMo catalysts show higher hydrogenation properties for the conversion of ketonic groups and higher decarboxylation selectivity in the conversion of the ester.