Thermal oxidation of carbon monoxide in air using various self-prepared catalysts

Abstract

Carbon monoxide (CO) is a very toxic pollutant emitted from wood fired boiler, which is widely used in small and medium enterprises in Vietnam. The treatment of CO containing flue gas faces many difficulties due to the inert property of CO and cannot be removed by traditional adsorption and absorption methods and one of the effective CO treatments is catalytic oxidation. Therefore, we aimed to prepare various catalysts on different carriers for treatment of CO in flue gas, including γ-Al₂O₃-based metal oxides (Co₃O₄/Al₂O₃, Cr₂O₃/Al₂O₃, and CuO/Al₂O₃), CuO–MnOx/OMS-2, and CuO-MnOx/zeolite. The CO removal tests were conducted in a continuous fixed bed reactor in laboratory scale with temperature range of 50 – 550 ^oC. The characteristics of catalytic materials were then determined by various methods such as Brunauer-Emmett-Teller measurement, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Results showed that CuO-MnOx/OMS-2 was the best catalyst with high removal efficiency of 98.41% at reactor temperature of 250 ^oC while gas outlet temperature of < 50 ^oC, proving the suitability of this material for practical treatment of CO in flue gas. The reaction follows Mars-Van-Krevelen mechanism with the presence of Cu²⁺-O^2--Mn⁴⁺ ↔ Cu⁺-o-Mn³⁺ + O₂ redox in the structure of the material. Moreover, the effect of environmental factors such as flow rate, inlet CO concentration, and catalysts amount on the CO removal efficiency were investigated and noted for designing and operation purposes. Concentration of outlet CO met well QCVN 19: 2009/BTNMT - National technical regulation on industrial emissions for dust and inorganic substances. Therefore, CuO-MnOx/OMS-2 catalyst material could be a potential catalyst for treatment of CO in flue gas of boiler.