Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

Abstract

Metal nickel and copper grids are shown to be suitable supports for structured combustion catalysts. The increase of specific surface area (SSA) of metal grids was achieved due to the porous outer layer with the structure of Raney metal developed on the wire surface. Transition metals (Co, Cu, Mn, Cr) oxides were deposited as active components on the pre-oxidized support and tested in total propane oxidation. Cobalt oxide demonstrated the highest activity. Reductive pre-treatment in the flow of hydrogen resulted in a more active catalyst than the activation in oxygen atmosphere. This effect was assigned to the partial reduction of Co 3 O 4 until metallic Co, which was detected by XPS on the catalyst surface. Deactivation of the pre-reduced Co-oxide catalyst was observed during propane combustion in excess of oxygen and was ascribed to the oxidation of partially reduced active phase. After 4 h on stream, the catalyst reached his steady-state and showed stable activity without further deactivation. The catalytic activity expressed in the terms of propane conversion was observed to depend on the propane/oxygen ratio.

Structured combustion catalysts based on sintered metal fibre filters

“…As reported by different authors [6,[22][23][24], cobalt oxide based catalysts generally are very active in total hydrocarbon oxidation. However, their activity depends on the cobalt oxidation state under the reaction conditions.…”

“…However, their activity depends on the cobalt oxidation state under the reaction conditions. In particular, catalytic performance of cobalt oxide is dependent on the propane/oxygen ratio [6,22]. The pre-reduced catalyst demonstrates higher activity and stability in a sto- ichiometric reactant mixture.…”

“…This behaviour was assigned to partial reduction of the Co oxide particles. Highly dispersed metallic Co species on the particle surface were responsible for the enhanced catalyst activity [6,22]. Oxidation of partially reduced active phase during propane combustion in excess of oxygen leads to catalyst deactivation.…”

“…In catalytic reactor-incinerators the effective catalysts for total oxidation of volatile organic compounds. Recently, we have shown that the catalysts based on woven glass fibres [2,3] and metal wire grids [4][5][6] are suitable for the design of structured combustion reactors. Glass fibre materials made from very thin filaments (d = 5-20 m) have open regular macrostructure providing a low pressure drop during the gas passage in addition to mechanical elasticity and thermal shock resistance.…”

Hydrogen production for fuel cell application in an autothermal micro-channel reactor

“…After evaporation of water, the plates are heated to 120 • C for 15 min melting the cobalt salt homogenizing the catalyst layers along the channels. Cobalt oxide is formed by calcination for 2 h at 350 • C [10]. In this way 22 mg of cobalt oxide were deposited on each plate.…”