Effect of niobium addition to Co/γ-Al2O3 catalyst on methane combustion

In this work, the effect of niobium addition on textural, structural, acidic, and catalytic properties of Co/gamma-Al2O3 catalysts for use in the total combustion of methane was studied. The catalysts were prepared by using the sol-gel technique and characterized by X-ray diffraction (XRD), infrared spectroscopy of adsorbed pyridine (IR), nitrogen adsorption (BET surface area), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), transmission electron microscopy in conjunction with energy-dispersive X-ray analysis (STEM-EDX), and activity in the total oxidation of methane. Results show that all cobalt-containing catalysts, regardless of the type of support, decrease the light off temperature of methane compared to pure gamma-Al2O3. Therefore, the addition of 1.0% (by weight) of niobium to cobalt-containing alumina catalysts promoted a negative effect on the catalytic activity. Both cobalt-containing catalysts (4.5 and 9.3%, by weight, of Co) show a higher catalytic activity when compared to cobalt-containing niobia-alumina catalyst (6.3%, by weight, of Co). The lower activity of the niobia-containing catalysts may be associated to their acidic and textural properties. (c) 2006 Elsevier B.V. All rights reserved.