Impregnation organic carbon precursors

An alternative method to densify a porous C/C composite is the impregnation with liquid organic carbon precursors and the succeeding recarbonization in subsequent densification cycles. 

Firstly, a mesoporous silica S , like SBA-15 is impregnated with an organic carbon source [5]. Carbonization of this precursor results in a silica/carbon composite, from which the mesoporous carbon C is obtained by dissolution of the silica. The pores of this carbon are impregnated with a gel for the synthesis of a zeolite which is subsequently submitted to a hydrothermal synthesis yielding a zeolite/carbon composite. Combustion of the carbon and the template molecules should result in mesoporous zeolite Z . 

In a much earlier patent, the removal of organics from exhaust gases by oxidation over a supported uranium oxide catalyst was reported by Hofer and Anderson [39]. The catalyst was 4% U3O8 supported on alumina spheres. The authors used the incipient wetness technique to impregnate alumina with uranyl nitrate solution. In this case the catalyst precursors were calcined at 700°C for 3 h to decompose the uranium salt. The use of other uranium compounds as starting materials was mentioned and these included uranyl acetate, uranium ammonium carbonate and uranyl chloride. The alumina-supported catalyst had a surface area of ca 400m g and further added components, such as copper, chromium and iron, were highlighted as efficient additives to increase activity. 

Activated Carbon With a surface of 300-2000 m g and a pore diameter of 1-5 nm, activated carbon is an outstanding adsorbent for a multitude of substances. It is produced by gentle heating of organic precursors like wood, turf or coconut peel, but also of pit-coal etc. The activation (to obtain the required porous structure) results either from hydrothermal surface reaction with water vapor or from impregnating the starting material with agents that cause oxidation and... 

Erkey and co-workers [59-61] prepared Pt- and Ru-doped carbon aerogels using a supercritical deposition method. This involved dissolution of an organometallic precursor in a supercritical fluid and the exposure of a solid substrate to this solution. After impregnation of the support with the metal precursor, it was converted to the metal form by different methods. Dimethyl(l,5-cyclooctadiene) platinum(ll) was used as a precursor for Pt [59,60], and two different Ru complexes, trisacetylacetonate Ru(lll) and Ru(cod)(tmhd)2, were used for Ru [61], Monolithic organic and carbon aerogels... 

The template method is used to prepare both microporous and mesoporous carbons as dependent on the very templates and raw materials. The method consists of the impregnation of finely porous precursors by an organic solvent (e.g., furfuryl alcohol), its carbonization in fine pores, and in dissolution of a precursor. 

---