Influence of Potassium Absorption on the Change of Crystallite Size of Coke with Heating Temperature

Abstract

Effects of potassium absorption on relation between graphite crystallite size of coke and heat-treatment temperature have been examined. The results are summarized as follows :
1) A crystallite size of coke, Lc, decreases when the heat-treated coke absorbed potassium. However a general tendency that the Lc increased with increasing temperature is maintained. On the other hand, another crystallite size, La, is not affected by the potassium absorption.
On the basis of the above observation, it is estimated that the remarkable deterioration of the coke is due to formation of an intercalation compound in the crystal.
2) The Lc decreases with increasing potassium content and then it reaches a limiting size when the potassium content reaches about 6 mass%. The limiting size depends on the heat-treatment temperature.
The decrease in the Lc in a low drum index coke was greater than that in an ordinary coke, but it was impossible to explain as due to the difference of the limiting concentration.