Kinetic analysis of element evolution during low-temperature oxidation of coal

The complex macromolecular matrix of coal was divided into the elements of C,O,H,S and N,which were involved in the oxidation reaction. Based on the changes of element contents during coal oxidation process at low tem- perature,the three kinetic models,including pseudo-first-order kinetics model,Coats and Redfern’ s model,and Free- man and Carroll’s model,were introduced to investigate the kinetic characteristics of coal oxidation at low tempera- ture. Kinetic study reveals that the evolutions of these elements during coal oxidation at low temperature follow pseudo- first order kinetics and Coats and Redfern’s model. The activation energies for these elements evolution in the oxida- tion process by using the pseudo-first order kinetics have been found to be almost similar to those calculated by apply- ing the Coats and Redfern’s equation. The reaction rates computed by the pseudo-first order kinetics are very low and have been found to be 10-5 -10-6 ,suggesting a very low rate of successful collisions for the formation of activated com- plex. A kinetic compensation effect between the activation energy and exponential facto was also observed for the evo- lutions of these elements.