Infoscience

Journal article

Structured combustion catalysts based on sintered metal fibre filters

Novel efficient structured combustion catalysts based on sintered metal fiber filters (MFF) were developed. To increase sp. surface area (SSA), metal fibers were coated by crack-free porous oxide films of SiO2, Al2O3, porous glass, and mesoporous SBA-15 silica. The composite materials presented uniform open macrostructure of the non-treated MFF filters and were suitable supports for deposition of catalytically active phases (Pd, Pt, and Co3O4). These catalysts were tested in hydrocarbon (CH4, C3H8) combustion. Co3O4 supported on MFF without any coating (6.8% Co3O4/MFF) was the most active for propane total oxidn. At the same time in methane combustion the activity of this catalyst was relatively low. Pd supported on the MFF coated by mesoporous SBA-15 film (0.5% Pd/SBA-15/MFF) demonstrated the highest activity in methane total oxidn. due to the high palladium dispersion. The SBA-15 film supported on MFF provided the highest dispersion of the deposited noble metals (Pd, Pt) with an av. particle size .apprx.2.0 nm. The metal nanoparticles formed within the mesopore channels were stable against sintering during calcination and the particle diam. was obsd. not to exceed the diam. of the silica pores. These catalysts did not undergo deactivation under reaction conditions at temps. up to 500 Deg. On the contrary, the Pd supported on MFF coated by the microporous SiO2 and Al2O3 films, prepd. by sol-gel technique, suffered from metal sintering during the calcination step and also during reaction, demonstrating strong catalyst deactivation. The catalytic filters are suitable materials for assembling different multiple layers to obtain structured catalytic beds with the compn./concn. gradients of active component in the axial direction. The enhanced overall catalytic performance was obsd. in adiabatic catalytic reactor during propane combustion due to a synergy of the 0.5% Pd/SBA-15/MFF and the 0.5% Pt/SBA-15/MFF catalytic layers assembled in the appropriate order forming gradient catalytic bed. [on SciFinder (R)]

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