Coating a monolith substrate with catalyst component

Abstract

A method of coating a honeycomb monolith substrate comprising a plurality of channels with a liquid comprising a catalyst component comprises the steps of: (i) holding a honeycomb monolith substrate substantially vertically; (ii) introducing a pre-determined volume of the liquid into the substrate via open ends of the channels at a lower end of the substrate; (iii) sealingly retaining the introduced liquid within the substrate; (iv) inverting the substrate containing the retained liquid; and (v) applying a vacuum to open ends of the channels of the substrate at the inverted, lower end of the substrate to draw the liquid along the channels of the substrate.

1 .- 17 . (canceled) 
     
     
         18 . A catalysed wallflow filter substrate monolith to which the manufacturer of the wallflow filter substrate monolith has pre-coated to inlet channels thereof a surface membrane layer comprising finely divided refractory solids, wherein the outlet channels comprise an axially substantially uniform coating profile of catalyst washcoat, which catalysed wallflow filter substrate monolith is obtainable by coating a honeycomb monolith substrate comprising a plurality of channels with a liquid comprising a catalyst component with a method comprising the steps of:
 (a) holding a honeycomb monolith substrate substantially vertically;   (b) introducing a pre-determined volume of the liquid into the substrate via open ends of the channels at a lower end of the substrate;   (c) sealingly retaining the introduced liquid within the substrate;   (d) inverting the substrate containing the retained liquid; and   (e) applying a vacuum to open ends of the channels of the substrate at the inverted, lower end of the substrate to draw the liquid along the channels of the substrate.   
     
     
         19 . (canceled) 
     
     
         20 . A catalysed wallflow filter substrate monolith according to  claim 18 , wherein the porosity of the wallflow filter substrate monolith prior to coating is from 40 to 80%. 
     
     
         21 . A catalysed wallflow filter substrate monolith according to  claim 18 , wherein a mean pore volume of the wallflow filter substrate monolith prior to coating is from 8 to 45 μm. 
     
     
         22 . A catalysed wallflow filter substrate monolith according to  claim 18 , wherein the catalyst washcoat is a NO x  trap, a catalysed soot filter washcoat comprising supported platinum group metal or a NH 3 -SCR catalyst. 
     
     
         23 . A catalysed wallflow filter substrate monolith according to  claim 22 , wherein the NH 3 -SCR catalyst comprises a transition metal exchanged zeolite. 
     
     
         24 . A catalysed wallflow filter substrate monolith according to  claim 23 , wherein the transition metal is selected from the group consisting of copper, iron, cerium and mixtures of any two or more thereof and the zeolite is selected from the group consisting of Ferrierite, CHA, BEA and MFI (ZSM-5). 
     
     
         25 . A catalysed wallflow filter substrate monolith according to  claim 24 , wherein the transition metal exchanged zeolite is selected from the group consisting of Cu/CHA, Fe/Ferrierite, Fe/ZSM-5, Fe—Ce/ZSM-5, Fe/BEA and Fe—Ce/BEA.