Low temperature complete combustion of dilute propane over Mn-doped ZrO2 (cubic) catalysts

Combustion of dilute propane (0×9 mol%) over Mn-doped ZrO2 catalysts prepared using different precipitating agents (viz. TMAOH, TEAOH, TPAOH, TBAOH and NH4OH), having different Mn/Zr ratios (0×05–0×67) and calcined at different temperatures (500–800°C), has been thoroughly investigated at different temperatures (300–500°C) and space velocities (25,000–100,000 cm3 g–1 h–1) for controlling propane emissions from LPG-fuelled vehicles. Mn-doped ZrO2 catalyst shows high propane combustion activity, particularly when its ZrO2 is in the cubic form, when its Mn/Zr ratio is close to 0×2 and when it is prepared using TMAOH as a precipitating agent and calcined at 500–600°C. Pulse reaction of propane in the absence of free-O2 over Mn-doped ZrO2 (cubic) and Mn-impregnated ZrO2 (monoclinic) catalysts has also been investigated for studying the relative reactivity and mobility of the lattice oxygen of the two catalysts. Both reactivity and mobility of the lattice oxygen of Mn-doped ZrO2 are found to be much higher than that of Mnimpregnated ZrO2. Propane combustion over Mn-doped ZrO2 catalyst involves a redox mechanism.