Combustion kinetics of the coke on deactivated dehydrogenation catalysts

• Three types of coke were identified on the deactivated dehydrogenation catalysts.
• Activation energies (Ea) of different types of coke combustion were obtained.
• The reaction order of the three types of carbon and oxygen was calculated.
• Mechanism and procedure of the catalytic coke combustion were discussed.

The coke combustion kinetics on the deactivated catalysts for long chain paraffin dehydrogenation was studied by the thermogravimetry and differential thermogravimetry (TG–DTG) technique. The amount and H/C mole ratio of the coke were determined by the TG and elemental analysis. And the comprehensive coke combustion model and catalytic combustion mechanism were also proposed. The results showed that three types of coke existed, which were located on the metal sites (C1) and the support sites surrounding (C2) and far from Pt (C3), respectively. The reaction order with respect to carbon was 1, 1/3 and 3/4, and to oxygen was 0, 1/2 and 3/4, respectively for the coke C1, C2 and C3. Moreover, the corresponding activation energy was 31, 107 and 127 kJ/mol, respectively.