Bulk Carbon Materials Synthesized By Hydrothermal Method And Its Catalytic Graphitization

Considerable efforts have been made in the preparation of monolithic carbon materials with high surface area/pore volume due to their wide variety of applications, and the advantages of mechanical stability, ease of handling and ease of recovery in monolithic form. Up to now, the main synthetic approaches includes templated method from silica monoliths, manufactured by carbon powder with binders, and carbonization of the monolithic organic aerogels. However, these methods have limitations in terms of scalability and economics. In this thesis, a simple hydrothermal carbonization (HTC) was employed as a green, efficient method to prepare monolithic carbons with high thermal stability for the first time.In chapter 3, carbonaceous monoliths rich in sulfonic groups were synthesized by the HTC of the mixture of p-toluenesulfonic acid/glucose/resorcinol. The presence of the sulfonic groups was confirmed by the FT-IR and XPS. This material has shown good activity and stability in the reaction of acetalization of benzaldehyde. The acidic carbonaceous monoliths can be further carbonized and activated to produce monolithic carbons with high surface area and large pore volume. After 6h activation, samples were found to have a high surface area (>2000 m2/g) and large pore volume (>1.5 cm3/g). Because of the abundant micropores and mesopores, these activated carbon monoliths showed a significant higher performance in dye molecules adsorption than commercial activated carbons and CMK-3.It is well-known that the graphitic carbons possess enhanced electronic conductivity, thermal stability, and mechanical strength compared with the carbons with amorphous framework and can be readily used in the applications of capacitors, batteries, and other electrochemistry fields. In chapter 4, graphitic carbon monoliths have been prepared from glucose/resorcinol at the aid of metal salts. Results showed that it is easy to form partially-graphitic carbon monoliths by carbonization of Fe3+-impregnated carbon monoliths (two-step method). But in the one-step method, in which metal ions were added to the mixture of glucose/resorcinol before HTC, initial pH value and the type of metal salts added have a significant impact on the results. When using cobalt nitrate as a catalyst, adapting the initial pH value to near 7, monolithic carbons with graphite structure can be successfully synthesized. Based on the characterizations from TEM, XRD, we proposed a possible reaction mechanism for the graphitization in the one-step method. This material shows a much higher selectivity in the selective oxidation of benzyl alcohol (the selectivity of benzaldehyde was 89%) than the amorphous carbon monoliths (the selectivity of benzaldehyde was lower than 3%).