Synthesis of ordered micro–mesoporous carbons by activation of SBA-15 carbon replicas

Ordered mesoporous carbon (OMC) with hexagonal arrays of tubes (CMK-3) was synthesized by direct replication, using SBA-15 as template and propylene as carbon source. Microporosity was developed in these OMCs with either carbon dioxide or potassium hydroxide as activating agents; effects of these activation treatments on their pore structure were discussed. Porous texture was characterized by gas adsorption, morphology was examined by SEM and the degree of order of porous structure was evaluated by X-ray diffraction and TEM micrography. The specific surface area, microporous volume and total pore volume were markedly enhanced upon activation of CMK-3, but the long-range ordered structure gradually became more disordered. Potassium hydroxide activation develops the materials microporosity in a greater extent than with CO2, nevertheless moderate temperatures and activating agent proportions must be used in order to preserve the ordered mesoporous structure.

Either chemical activation (KOH) or physical activation (CO2) were performed on ordered mesoporous carbons (OMCs) obtaining simultaneously remarkable microporosity development and mesoporous system preservation. Bimodal micro–mesoporous carbons with narrow and tuneable pore sizes distributions are obtained.Figure optionsDownload as PowerPoint slideHighlights
► Microporosity is developed in OMC preserving the ordered structure.
► Carbons with bimodal, narrow and tuneable pore size distribution are prepared.
► Both physical and chemical activations increase significantly the micropore volume.
► Mesoporous order is lost under hard chemical activation conditions.