Catalysis of the graphite-CO2 reaction by iron from in-situ reduction of wustite over the range 870-1100 degrees C

Experimental results are reported on the catalytic enhancement of the Boudo uard reaction by iron produced in situ from wustite in the temperature rang e 870-1100 degreesC. Experiments were carried out under a carbon dioxide at mosphere and the isothermal weight loss of the samples was determined as a function of time. The experimental data were interpreted by recourse to a g rain model with the incorporation of Roberts and Satterfield's effectivenes s factor. Single porous disks made of carbon (graphite)-wustite mixtures we re employed in a thermogravimetric arrangement. The effects of temperature, reactant gas flow rate and fraction of wustite in the pellet on the rate c onstant for the chemical reaction, which is described according to Langmuir -Hinshelwood kinetics, were determined. It was found that iron freshly redu ced from wustite acted as a fairly strong catalyst for the solution loss re action, especially at lower temperatures. The catalytic effect of iron was observed to depend markedly on its history and the method of sample prepara tion. The presence of iron as a catalyst reduces the apparent activation en ergy to 24.0-34.0 kcal/mole, by comparison with 82.0 kcal/mole for the unca talysed Boudouard reaction.