Study of Ni-Co-ZrO2/Al2O3 Catalysts for Carbon Dioxide Reforming of Methane at Low CO2

Abstract

This work studied the composition of Ni-Co-ZrO2/Al2O3 catalyst on properties and efficiency of catalysts for carbon dioxide reforming of methane (CMR) when CO2 was fed as the limiting reagent and CH4 as the excess reactant. 9wt%Ni-1wt%ZrO2/Al2O3, 4.5wt%Ni-4.5%wtCo-1wt%ZrO2/Al2O3, 9wt%Co-1wt%ZrO2/Al2O3 and 7wt%Co-3wt%ZrO2/Al2O3 catalysts were prepared by wet impregnation method. The physicochemical properties of present catalysts were characterized by XRD, N2 adsorption-desorption H2-TPR and CO2-TPD. The CRM performance was determined in a tubular fixed-bed reactor at 600 °C for 6 h with limiting of carbon dioxide. The carbon deposition on spent catalysts were examined by TGA. The results showed that Co-ZrO2 catalysts provided greater activities, selectivity toward H2 and stability than Ni-ZrO2 and Ni-Co-ZrO2 catalysts. 9wt%Co-1wt%ZrO2/Al2O3 provided higher reactant conversions and H2/CO ratio than 7wt%Co-3wt%ZrO2/Al2O3 while the minimum coke formation was observed on spent 7wt%Co-3wt%ZrO2/Al2O3. It is because oxophilic properties and oxygen vacancy sites in Co-ZrO2 increase CO2 dissociative adsorption as well as oxygen transport on the catalyst surface. HIGHLIGHTS This work developed Ni-Co-ZrO2/Al2O3 catalysts for carbon dioxide reforming of methane (CMR) when CO2 is fed as the limiting reagent demonstrated petroleum refinery application. Remarkable points of this work are revealed below. Co-ZrO2 catalysts provided greater reactant activities, selectivity toward H2 and stability than Ni-ZrO2 and Ni-Co-ZrO2 The oxophilic property accompanied with oxygen vacancy sites in Co-ZrO2 increase CO2 dissociative absorption and oxygen transport on the catalyst surface. 9wt%Co-1wt%ZrO2/Al2O3 provided relative highest reactant conversions and highest H2/CO ratio. 7wt%Co-3wt%ZrO2/Al2O3 presented the minimum coke formation. GRAPHICAL ABSTRACT