Decarboxylation of Beypazari lignite by the catalytic effect of Cr3+ and Fe3+ ions

Abstract

The catalytic effect of the transition metal ions Cr 3 + and Fe 3+ on the decarboxylation of Beypazari lignite was investigated in terms of the change in calorific values of the decarboxylated lignite samples obtained after the decarboxylation process and activation energies of the decarboxylation processes. The optimum temperature to run the decarboxylation experiments was determined as 150°C and 2% Cr 3 + or Fe 3+ loadings for the raw coal samples and 1% Cr 3 + or Fe 3+ metal loadings for the demineralized coal samples were found to be the optimum values to obtain the highest calorific value coal after decarboxylation reactions. Addition of Cr 3 + or Fe 3+ to raw and/or demineralized coal samples decreased the activation energies of the decarboxylation reactions by about 40% (raw coal samples) and 30% (demineralized coal samples). Activation energies calculated for experiments with Cr 3 + loaded coal samples were lower than those for Fe 3+ loaded coal samples, indicating higher catalytic activity of Cr 3 + as a catalyst.