Influence of the textural parameters of resorcinol–formaldehyde dry polymers and carbon xerogels on particle sizes upon mechanical milling

Porous carbons find various applications in catalysis, electrochemical storage or sorption. Prior to use, their particle sizes need however to be controlled according to the targeted application. In this study, the grinding behavior of materials prepared from aqueous resorcinol–formaldehyde mixtures and displaying different pore textures was studied in detail. Both dry polymer gels and pyrolyzed carbon xerogels were compared in terms of particle size distributions after planetary ball-milling.

The results show that the pore texture and the qualitative hardness of the materials have a strong influence on the grinding behavior, especially if carbon xerogels pyrolyzed before grinding are considered. On the other hand, it appears that the milling of polymer gels, followed by a pyrolysis step, is the most efficient way to obtain homogeneous particle size distributions, for all of the investigated mesopore textures. In this case, carbon particles displaying a narrow grain size distribution centered on a mode value near 10 μm are successfully obtained after similar grinding durations, with retention of the mesopore texture of the starting materials. This work also demonstrates the possibility of using mercury intrusion porosimetry as an interesting tool to assess simultaneously the mesopore dimensions and the particle sizes of porous powders.