CERAMIC HONEYCOMB COMPOSITE STRUCTURE CATALYST SUPPORTED THEREBY AND METHOD OF PRODUCING THE SAME

摘要

1485640 Coated catalyst support NIPPON GAISHI KK 14 Nov 1974 [3 Oct 1974] 49355/74 Headings B1E B1F and B2E [Also in Division Cl] A ceramic honeycomb composite structure of use as a catalyst support in the treatment of I.C. engine exhaust gases comprises a ceramic honeycomb having a multiplicity of parallel channels 4 separated by dividing-walls 5, wherein at least the walls have a ceramic coating layer 3 integrally applied thereto, the ceramic layer having a plurality of pores therein such that the sum of the volumes of pores of diameters 5 microns or more is at least 0.1 cc/g. The ceramic layer may be applied by coating the honeycomb, which may be formed by extrusion with hexagonal, square, rectangular or triangular channels, with a ceramic material having a grain size distribution within a specific range, i.e. that defined by lines A-B-C-D-E-F in Figure 2 (not shown), drying and sintering. The honeycomb and ceramic layers may be formed of the same material e.g. cordierite. The honeycomb may alternatively be formed of mullite, alumina, silicon carbide or silicon nitride. For use as a catalyst support, an additional coating layer of relatively high surface area, e.g. 20-300 m2/g may be applied to the ceramic layer which itself typically has a surface area of the order of 0.1 m2/g. The additional layer may be gamma-alumina and/or magnesia. The catalytic material applied may be a platinum group metal or a Cu, Fe, Ni, Co, Mn, Re, Cr, Mo, W, V or Nb component. The Examples relate to catalysts comprising platinum on a gamma-alumina layer.