Growth of carbonaceous nanomaterials over stainless steel foams. Effect of activation temperature

•Stainless steel foams are suitable catalytic substrates to develop coatings of carbonaceous nanomaterials, like CNFs or graphene.•The oxidation temperature of the metallic foam affects to the type and morphology of the carbonaceous nanomaterials obtained.•The maximum productivity of CNMs, 17 mg C/g foam.min, is obtained after oxidation, reduction and reaction at 800 °C.•The highest adherence of the carbonaceous deposits to the metallic foam is obtained after oxidation, reduction and reaction at 800 °C.•Elevated reduction temperatures, ca. 900 °C, cause a loss of productivity due to the sintering of Fe and Ni nanoparticles exposed at the surface of the foam.

Some of the problems that occur during the operation of chemical reactors based of structured catalytic substrates, as monoliths, foams, membranes, cloths, fibres and other systems, are related to the preparation of long term stable coatings. Frequently, the deposition of the catalytic layer is carried out by washcoating, requiring this step a cautious attention, especially in the case of complex geometries, like of that of foams or cloths. In the case of the deposition of layers of carbonaceous materials (CNMs), an alternative route, avoiding the washcoating, it is their direct growth by catalytic decomposition light hydrocarbons (also called CCVD), over the surface of the metallic substrate. In this case, if the metallic substrate is of stainless steel, it already contains the catalytic active phases like Fe and Ni.In order to optimize the process of CNMs growth over structured metallic substrates, we are studying the effect of the main operational variables of the ethane decomposition reaction on stainless steel foams. In this contribution we present a study of the influence of the temperature of the activation (oxidation and reduction) stage on the type and morphology of the carbonaceous materials formed. The results obtained allow us to determine the optimal operating conditions to maximize the amount and the selectivity of the process to obtain a given type of CNM.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (132 K)Download as PowerPoint slide