The unit represents a honeycomb structure (Fig.1), produced from steel strip (strips of different metals, steels and alloys can be used, but presently we use the heat resistant chromium-aluminum steel strip OC404 (Sandvik, Sweden). Thickness of the strip is 30-40 microns and the width is 100-300 mm) with sprayed ceramic support on the basis of alumina, alumina-magnesia or, for special purposes, zirconia. On demand, practically any metal oxides (e.g. copper, iron, cobalt, nickel etc.) can be introduced into ceramic support.
Fig.1. Honeycomb structure metal based catalytic unit
Metal based catalytic unit (MCU) can be produced in cylindrical shape with height up to 100 mm and diameter divisible by 40 mm - namely 40, 80, 120, 160, 200 etc. The dimensions of triangular channels (Fig.2) are ~2,5/2,5/3 and ~4,7/4,7/6,5 mm.
Fig.2. Corugation step, mm
The sprayed ceramic supports (Fig.3) have an excellent adhesion to metal substrate and can be characterized by high resistance to vibration, thermal shock and gas erosion.
Fig.3 Flat and corrugated samples
The sprayed ceramic supports (Fig.4) have high specific surface area (usually 70-80 m2/g, but can reach up to hundreds of m2/g) and considerable catalytic properties, which is enough in many cases (e.g. in case of tars decomposition in gasification process the alumina-magnesia support with nickel oxide).
Fig.4. SEM pictures: A-alumina_magnesia based support; B-C zirconia based support
For special purposes metal honeycomb structure with special mezo porous support on the basis of carbon nanotubes can be produced (Fig. 5). This development is fulfilled in cooperation with CARBON GROUP, POLITECNICO DI TORINO www.polito.it/carbongroup.
Fig.5. Growth of carbon nano tubes on AMIAGUS support
MCU also can be produced with different catalysts deposited on internal walls of honeycomb structure. It means, that, for example, two walls can be coated by hydrotalcite for NOx adsorption and third – catalyst for NOx reduction (WO2006/041273A1). Other variants of coating also are possible as impregnation with needed noble metal solutions according usual procedure.
