gas flow direction are obtained in the catalytic unit as shown in fig3 fig1 depicts a detail as seen from the end of the honeycomb 4 of a catalyst in this case both sides of a flat strip 1 have a first support and both sides of a corrugated strip 2 have a second support when packed tightly these form in each channel 3 two different catalytic surfaces 5 and 6 fig2 shows a detail as seen from the end of the honeycomb of a catalyst in this case the first side 5 of a flat strip 1 is coated with a first support and its second side 6 with a second support the first side 7 of the corrugated strip 2 is coated with a third support and its second side 8 with a fourth support in this case when packed tightly the honeycomb comprises alternate channels the catalytic surfaces of which are 5 and 8 and respectively 6 and 7 in this case the gas flowing through has four different catalytic surfaces having support and noble metal compositions optimal for specific reactions after coating the strips are dried and wound into a loose temporary roll which is calcined after calcination impregnations with noble metals are carried out for example according to the examples below one measurable quantity essential for the functioning of a catalyst intended for the purification of gases is the light off temperature this means the temperature at which 50 of a certain gas component such.