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Authors |
Kitirote Wantala, Fe Corazon L See Go, Vince Carlo C Garcia, Prae Chirawatkul, Narong Chanlek, Pinit Kidkhunthod, Ralf Ruffel M Abarca, Mark Daniel G de Luna |
| Abstract |
In this study, cryptomelane-type manganese oxide (K-OMS-2) was used as a catalyst for the thermal oxidation of toluene. The catalyst was synthesized via the hydrothermal route and doped with Cu, Ce, and co-doped with the same metals by ex-situ and in-situ methods. The effects of dopant type, dopant concentration, and dopant impregnation method on the thermal catalytic activity of K-OMS-2 were examined. Initially, 1%, 2%, and 4% by mole Cu or Ce were incorporated by wet impregnation to the hydrothermally synthesized K-OMS-2 and in-situ direct hydrothermal method. The physicochemical properties were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and thermal gravimetric analysis (TGA) techniques. Gaseous toluene was made to react with the doped catalysts in a packed bed reactor attached to gas chromatography equipment to measure the amount of unreacted toluene. Results showed K-OMS-2 doped with 4% by mole Cu and 1% by mole Ce gave excellent thermal catalytic efficiency results at 180鈥壜癈 reaction temperature. Meanwhile, K-OMS-2 co-doped with Ce and Cu with a mole ratio of 0.25:3.75 per 100 moles of K-OMS-2 gave the best catalytic activity and complete oxidation at 180鈥壜癈 reaction temperature. Comparing K-OMS-2 doped with the same metal ratios, in situ doped catalysts led to higher toluene removal percentages. Meanwhile, the 72-h stability test showed that the optimum co-doped catalysts are capable of entirely oxidizing toluene even after prolonged and continuous use. |
Mindanao State
University - Iligan Institute of Technology