Publisher Summary The properties of a surface are influenced by the surface groups and the knowledge of their existence and of their chemistry are important for many technological processes This chapter examines the surface compounds on carbon—microcrystalline carbon, graphite, and diamond—on silica, on titania, and on alumina and silica–alumina Most important and best known among the surface compounds of carbon are those with oxygen and with sulfur Thus, two kinds of surface oxides are known Basic surface oxides are formed always when a carbon surface is freed from all surface compounds by heating in a vacuum or in an inert atmosphere and comes into contact with oxygen only after cooling to low temperatures Acidic surface oxides are formed when carbon is treated with oxygen a temperatures near its ignition point Unambiguous identification of carboxyl groups has been achieved by two reactions of the acyl chlorides: Friedel–Crafts reaction and Schmidt rearrangement

Chemical Identification of Surface Groups

Modification of graphite electrode materials for vanadium redox flow battery application—I. Thermal treatment

Heterogeneous Kinetics of Coal Char Gasification and Combustion

During the last few decades, concerns have grown on the negative effects that diesel particulate matter has on health. Because of this, particulate emissions were subjected to restrictions and various emission-reduction technologies were developed. It is ironic that some of these technologies led to reductions in the legislated total particulate mass while neglecting the number of particles. Focusing on the mass is not necessarily correct, because it might well be that not the mass but the number of particles and the characteristics of them (size, composition) have a higher impact on health. To eliminate the threat of diesel particulate matter, essentially absolute filtration in combination with the oxidation of all emitted hydrocarbons is what will be required. After two decades of development, the first filters will soon be introduced on a large scale. Many different problems had to be overcome; it was especially important that the filter was robust and its regeneration was controllable. The key technol...

Science and technology of catalytic diesel particulate filters

Importance of carbon active sites in the gasification of coal chars

Graphon, a highly graphitized carbon black, was oxidized to seven levels of burn-off between zero and 35%. The active surface area of the oxidized samples was determined by measuring the coverage of the surface with oxygen complex upon exposure of the samples to O2 at 300 deg for 24 hr. After removal of the complex, the Graphon samples were subsequently treated with additional O2. The amount of oxygen complex formed on the surface during reaction could be followed by a material balance and at the end of a run by outgassing. From the data, unoccupied active surface areas were calculated. Rate constants for O2 depletion and product formation, calculated on the basis of unoccupied active area, were essentially constant over most of the burn- off range studied. On the other hand, rate constants, calculated on the basis of BET surface area, showed a considerable increase with burn-off.

F. J. Vastola

Papers

The importance of active surface area in the carbon-oxygen reaction1,2