Mechanism of the potassium catalysed gasification of carbon in CO2

Summary Carbon gasification reactions form the basis of several important industrial processes. This Chapter considers the fundamental science of gasification of carbons including cokes and chars. The distinction is made between chemical and diffusional control of reaction rate and the influences of porosity in the carbon. Rates of gasification, referred to as reactivity parameters, are a function of reacting gas, temperature, pressure, impurity content and structure of the carbon. The use of active and reactive surface areas to normalise gasification rates as a basis for comparison is explained. Mechanisms of reaction of carbon with atomic and molecular oxygen, carbon dioxide, steam, oxides of nitrogen and hydrogen are reviewed and compared. Catalysis of oxidation reactions is assessed in terms of mechanisms involving oxygen-transfer stages and topographical changes causing pitting and channelling. Inhibition of gasification is introduced. The difficulty in using the concept of reactivity in a rigorous comparative way is discussed.

M.T. Thomas

Papers

The inverse oxidation phenomenon