Nb2O5 Promoted Base Metal Oxide Catalysts Used for Air Pollution Abatement in Stationary Plants

Catalytic oxidation is a very efficient way for the abatement of low concentrations of Volatile Organic Compounds (VOCs). The most active catalysts used for oxidation are supported noble metals. However the main drawback with noble metals is their high price. Our goal is to consider transition metal oxides as possible replacements for expensive precious metals for low-temperature stationary abatement applications. Current research in our group has found that niobium oxide (Nb₂O₅) is worthy of additional studies as a promoter in altering the oxidation states of base metal oxides. Consequently, bimetallic catalysts supported on Nb₂O₅ were synthesized to achieve the development of stable oxidation. Both Nb₂O₅ and Al₂O₃ carriers were pre-calcined at 800˚C for 2hr. Then, the calcination temperature for metal-supported catalysts was experimentally determined using temperature programmed decomposition in air using thermogravimetric analysis (TGA). The C₃H₈ oxidation reactions were carried out in a fixed-bed quartz flow reactor at atmospheric pressure. The reaction conditions were as follows: C₃H₈: 0.1 vol. %, O₂: 18.9 vol. % and N₂ balance. Under ambient conditions, the gas hourly space velocity (GHSV) was 65 000 h^-1 and catalysis volume is 0.1 ml. Effluent gases of were continuously analyzed by micro GC. Isothermal aging tests were conducted to assess the stability of the catalysts at 400 ˚C in the air. Results suggest a strong interaction between niobium oxide and the active components.