Exhaust system for a compression ignition engine comprising a water adsorbent material

Abstract

An exhaust system for a compression ignition engine comprising: a water adsorbent material; and a catalyst composition for treating an exhaust gas pollutant produced by the compression ignition engine; wherein the water adsorbent material is: (i) arranged to contact exhaust gas from the compression ignition engine before the catalyst composition; and (ii) in thermal communication with the catalyst composition.

1 - 20 . (canceled) 
     
     
         21 . A diesel engine exhaust system comprising an oxidation catalyst, wherein the oxidation catalyst comprises:
 a water adsorbent material;   a catalyst composition for treating an exhaust gas pollutant produced by the diesel engine, wherein the catalyst composition comprises a platinum group metal (PGM) and a support material, wherein the platinum group metal (PGM) comprises platinum; and   a substrate;   wherein the catalyst composition and the water adsorbent material is each disposed on the substrate, wherein a first washcoat layer comprising the water adsorbent material is disposed on a second washcoat layer comprising the catalyst composition such that the water adsorbent material is arranged to contact exhaust gas from the diesel engine before the catalyst composition.   
     
     
         22 . A diesel engine exhaust system according to  claim 21 , wherein the water adsorbent material comprises a zeolite. 
     
     
         23 . A diesel engine exhaust system according to  claim 22 , wherein the zeolite has a silica to alumina ratio (SAR) of 100:1 to 8:1. 
     
     
         24 . A diesel engine exhaust system according to  claim 22 , wherein the zeolite has a pore size of from 3 Å to 15 Å. 
     
     
         25 . A diesel engine exhaust system according to  claim 22 , wherein the zeolite is be selected from the group consisting of faujasite, clinoptilolite, mordenite, silicalite, ferrierite, zeolite X, zeolite Y, ultrastable zeolite Y, beta zeolite, AEI zeolite, ZSM-5 zeolite, ZSM-12 zeolite, ZSM-20 zeolite, ZSM-34 zeolite, CHA zeolite, SSZ-3 zeolite, SAPO-5 zeolite and offretite. 
     
     
         26 . A diesel engine exhaust system according to  claim 21 , wherein the platinum group metal (PGM) comprises a combination of platinum and palladium. 
     
     
         27 . A diesel engine exhaust system according to  claim 21 , wherein the substrate monolith is a flow-through monolith or a filtering monolith. 
     
     
         28 . A diesel engine exhaust system according to  claim 21 , which further comprises an emissions control device selected from a diesel particulate filter (DPF), a lean NOx trap (LNT), a lean NOx catalyst (LNC), a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), a catalysed soot filter (CSF), a selective catalytic reduction filter catalyst, and a combination of two or more thereof. 
     
     
         29 . A vehicle comprising a diesel engine and a diesel engine exhaust system according to  claim 21 .