Carbon microspheres preparation, graphitization and surface functionalization for glycerol etherification

Abstract

An easy and cost-effective method to prepare mono-disperse carbon microspheres via a hydrothermal carbonization process (CHT) under moderate conditions (200°C) has been investigated. The preparation was carried out using glucose in aqueous solution. The results clearly revealed that the procedure employed allowed obtaining amorphous microspheres, 200–300nm in size, and spheres of 1–2μm, characterized by a surface area close to 600m2/g. TEM-EELS and XRD analyses demonstrated that the crystallinity grade of carbon micro-spheres significantly increases after N2 treatment at 1000°C for 6h. Moreover, the presence of surface functional groups, revealed by DRIFT analysis, allowed functionalizing the carbon spheres by sample inorganic acid treatment or by inorganic acid treatment followed by impregnation with fluorinated superacid ionomer (Hyflon). These catalytic systems resulted to be very active in glycerol etherification reaction, allowing obtaining, differently from a commercial A15 catalyst, a mixture of tert-butylethers containing a very low amount of side products.