Use of pillared clays in the preparation of washcoated clay honeycomb monoliths as support of manganese catalysts for the total oxidation of VOCs

摘要

Graphical abstractDisplay OmittedHighlights?Pillared clay-washcoated clay honeycomb monoliths as support of manganese catalysts.?The pillared clay allows incorporating higher amount of well distributed MnO2.?Acetone light-off temperature as low as 225°C, keeping activity even for 2400ppm.?Catalysts are stable in long-term experiments in propane and acetone total oxidation.?New possibilities for using pillared clays as catalytic support in VOCs combustion.AbstractManganese catalysts supported by impregnation onto honeycomb monoliths extruded from commercial clay, previously coated with aluminium-pillared clay, were prepared and tested in the total combustion of propane and acetone. Samples characterization included chemical analysis, nitrogen physisorption, electron microscopies (SEM-EDS, HAADF and EELS), XRD, TPR and O2-TPD experiments. The active phase (around 5wt%), consisting of MnO2particles as majority phase, with homogeneous size and shape, that tends to concentrate in some regions of the surface of the clay support, exhibited high efficiency to oxidize the two model VOCs investigated and stability in severe reaction conditions. Light-off temperatures as low as 225 and 330°C were found for the oxidation of acetone and propane respectively. The better performance observed in comparison to the monoliths without pillared clay was attributed to the higher active phase loading. Differences found as function of the VOC's nature and concentration were related to the different oxidation mechanisms proposed in literature, either just Mars-van Krevelen or this with also Eley-Rideal contribution, for acetone and propane respectively. These results combined with the intrinsic advantages of the honeycomb monolithic design open up new possibilities for using pillared clays as catalytic support in VOCs oxidation under more affordable conditions.]]>