Methane Combustion Using CeO₂-CuO Fibers Catalysts

Abstract

The use of three-way catalysts is an accepted method to minimize NOx and CO emissions generated by internal combustion engines. These catalysts are generally formed by the support, stabilizers, promoters metal and transition metals, the most used metals of the platinum group. The use of cerium as a promoter is usually related to its ability to store oxygen and structural aspects such as the property of increasing the dispersion of metals and slow change of phase of the stabilizing support. On the other hand, the metal copper was explored as a possible replacement for palladium and platinum in the reduction of NO by CO. In this work, fibers of cerium oxide doped with copper were obtained from an acetate solution of cerium and coppers nitrates and polyvinyl butyral (PVB). This solution went through the process of electrospinning to produce nanostructured fibers. After heat treatment, cerium oxide fibers were obtained. These fibers were characterized structurally by scanning electron microscopy (SEM), had their specific surface area determined by BET method, were subjected to thermogravimetric test to determine their thermal decomposition and were analyzed by X-ray diffraction. The catalytic activity was assessed by the amount of O₂ consumed and CO and CO₂ formed for the combustion of methane and air. SEM images show fibers oriented randomly in the substrate. TEM images show that the diameter of the fibers is approximately 100 nm and the size of its crystallites are around 20 nm. In the presence of the catalyst, the combustion reaction started around 500°C, with the consumption of methane and oxygen and the formation of CO and/or CO₂. There was no emission of NO and NOx gases during the tests with catalysts.