A comparative study on the kinetics of carbon dioxide reforming of methane over Pt–Ni/Al2O3 catalyst: Effect of Pt/Ni Ratio

Kinetics and surface reaction mechanism of CO2 reforming of methane (CDRM) was studied over 0.2%Pt–15%Ni/Al2O3 and 0.3%Pt–10%Ni/Al2O3 catalysts in order to determine the effect of Ni/Pt loading ratio on kinetic behavior. The simple power-law type rate expressions obtained for 0.3%Pt–10%Ni/Al2O3 and 0.2%Pt–15%Ni/Al2O3 have reaction orders of 1 and 1.09 for CH4 and 0.87 and 1.40 for CO2, respectively, confirming methane consumption rate for 0.2%Pt–15%Ni/Al2O3 sample is more sensitive to the increase in partial pressure of CO. The comparative analysis of meaningful surface reaction models for the catalysts and the optimized model parameters obtained revealed that the surface reaction mechanisms are completely different. CO inhibition effect is stronger and CO2 utilization is suppressed on the catalyst with high Ni:Pt loading ratio. On the other hand, with a decrease in Ni:Pt loading ratio, CH4 adsorption becomes weaker, ability of utilizing CO2 as the oxygen source gets stronger and CO inhibition effect is practically eliminated.

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• Power-law type rate expression obtained for 0.3%Pt-10% Ni/Al2O3 have reaction orders of 1 CH4 and 0.87 for CO2.
• Power-law type rate expression obtained for 0.2%Pt-15% Ni/Al2O3 have reaction orders of 1.09 CH4 and 1.40 for CO2.
• Surface reaction mechanisms are completely different for both samples.
• CO inhibition effect is stronger and CO2 utilization is suppressedon the catalyst with high Ni:Pt loading ratio.