Cobalt-, copper- and iron-containing monolithic aluminosilicate-supported preparations for selective catalytic reduction of NO with NH3 at low temperatures

Aluminium-doped mesoporous monolithic silica possessing fine mesopores has been prepared via the direct liquid crystal templating pathway using a non-ionic surfactant template and has been used as a support for cobalt-, copper-, and iron-based formulations in the selective catalytic reduction (SCR) of NO with ammonia in the presence of oxygen at low temperatures in the range of 373-723 K. The monolithic support was characterised by N2 gas adsorption at 77 K, powder X-ray diffraction (XRD) and NH3 adsorption at 373 K. Surface area, pore structure and surface acidity of the catalysts before and after being subjected to catalytic testing were determined, and good stability of pore structure and surface properties under SCR conditions was indicated. The NO conversions on aluminosilicate monolith-supported catalysts were compared with those observed on the reference catalyst, EUROCAT powder. The Co-functionalised catalysts appeared less relevant to DeNOx purposes. Two impregnated and two ion-exchanged catalysts containing copper and iron showed catalytic performance comparable to that of the reference catalyst. They produced only small amounts of undesired product N2O, the Fe-containing formulations being even more selective than EUROCAT. The nature of metal species in these catalysts was investigated with the aid of Cu 2p X-ray photoelectron spectroscopy (XPS) and 57Fe Mössbauer spectroscopy.