(405d) Ozone Removal Using New Structure of Matter for High Performance Heterogeneous Catalysis At Short Contact Time

Pleated Microfibrous Entrapped Catalyst (MFEC) manufactured from 8 μm diameter nickel fibers were tested for ozone decomposition at turbine bleed air conditions to demonstrate the improved catalytic performance over conventional monolith reactors.

In this research, ozone has been used as model compound. MFEC reactors were investigated under aircraft bleed air conditions of high temperature (100-200℃) and high face velocity (10-30 m/s) resulting an interlayer contact time of 67-200μsec. Precious metal (Pd, Ag) and transition metal (Mn) catalysts were impregnated on entrapped particles (e.g. γ-Al₂O₃) using incipient wetness method. Ozone test concentration was set at a high-demanding 1.5 ppmv. Results showed that a high level of ozone decomposition was achieved with a significant reduction of catalyst consumption. Compared with conventional aircraft filters, this can be a huge advantage in terms of material cost and labor. Because the entrapped small particles (150-250μ m) improve the contact efficiency significantly, this kind of reactor has shown high catalytic activity even though the contact time for the reactant has been shortened to 100μ s range due to the high face velocity. The ozone reaction kinetics has been analyzed using a first order plug flow model, which showed the reaction was external mass transfer limited. Mass transfer rate, effective reaction rate and overall efficiency factor were compared among packed bed, monolith and MFEC reactors. Also catalyst aging tests were carried out according to the frequency of commercial aircraft ozone abater replacement, which evaluated long-term performance of MFEC. XPS, TPR and chemisorption tests have been used to characterize catalyst deactivation mechanisms. Besides, several other aspects including humidity, system pressure been investigated for affection on the reaction.