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

Abstract

Combustion of dilute propane (0x9 mol%) over Mn-doped ZrO₂ catalysts prepared using different precipitating agents (viz. TMAOH, TEAOH, TPAOH, TBAOH and NH4OH), having different Mn/Zr ratios (0x05-0x67) 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 0x2 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.