Diesel emissions control after-treatment systems and related method

Abstract

A diesel emissions control system or diesel emissions control after- treatment (“DECAT”) system thermally stabilizes and catalyzes engine exhaust. The system generates substantial reduced volatile organic compounds (“VOCs”) and hydrocarbons (“HCs”), as well as selective catalytic reduction (“SCR”) of nitrogen oxides (“NOx”). The system treats exhaust gases rich in particulate matter (“PM”) prior to a downstream diesel particulate converter (“DPC”). The DPC agglomerates the PM into larger and heavier soot that may be more readily captured by a deep bed of composite wire mesh filters. The system includes a base metal catalyst with an iron-containing zeolite catalyst augmented with cerium-manganese oxide (the “IZCM Catalyst”).

What is claimed is: 
     
         1 . A diesel emissions control after-treatment (“DECAT”) system for treating exhaust prior to a diesel particulate converter, the system comprising:
 a supply source for injecting a reductant into an exhaust stream; and 
 a DECAT device for receiving the exhaust stream containing the reductant, the DECAT device including a thermal stabilizer section and a catalyst section, the thermal stabilizer section operative to reduce a temperature of the exhaust stream to 350° C. or less, the catalyst section including a base metal catalyst with an iron-containing zeolite catalyst augmented with cerium-manganese oxide (“IZCM catalyst”). 
 
     
     
         2 . The diesel emissions control after-treatment system of  claim 1 , wherein the thermal stabilizer section and the catalyst section are arranged such that the exhaust stream containing the reductant is first treated by the thermal stabilizer section and subsequently treated by the catalyst section. 
     
     
         3 . The diesel emissions control after-treatment system of  claim 1 , wherein the thermal stabilizer section and the catalyst section are contained within a common housing. 
     
     
         4 . The diesel emissions control after-treatment system of  claim 1 , wherein the thermal stabilizer section and the catalyst section are contained within separate housings. 
     
     
         5 . The diesel emissions control after-treatment system of  claim 1 , wherein the exhaust stream may be maintained within a range of approximately 250° C. to 350° C. 
     
     
         6 . The diesel emissions control after-treatment system of  claim 1 , wherein the thermal stabilizer section includes a wire mesh media. 
     
     
         7 . The diesel emissions control after-treatment system of  claim 1 , wherein the catalyst section is operative to substantially reduce VOC and HC. 
     
     
         8 . The diesel emissions control after-treatment system of  claim 7 , further wherein NOx is selectively catalytically reduced. 
     
     
         9 . The diesel emissions control after-treatment system of  claim 1 , further comprising at least one cooling device for condensing VOC fractions of PM. 
     
     
         10 . The diesel emissions control after-treatment system of  claim 1 , in combination with the diesel particulate converter. 
     
     
         11 . The diesel emissions control after-treatment system of  claim 1 , wherein the cerium-manganese component of catalyst section is operative to substantially reduce VOC and HC. 
     
     
         12 . The diesel emissions control after-treatment system of  claim 4 , wherein the separate housings are connected by a piping. 
     
     
         13 . The diesel emissions control after-treatment system of  claim 4 , wherein the reductant is injected into the piping. 
     
     
         14 . The diesel emissions control after-treatment system of  claim 1 , wherein the reductant is an ammonia source. 
     
     
         15 . The diesel emissions control after-treatment system of  claim 1 , wherein the reductant is urea. 
     
     
         16 . The diesel emissions control after-treatment system of  claim 3 , wherein the reductant is after the thermal stabilizer section before the catalyst section. 
     
     
         17 . A method of treating diesel exhaust prior to a diesel particulate converter, the method comprising:
 injecting a reductant from a supply source into an exhaust stream;   treating the exhaust stream containing the reductant with a thermal stabilizer section of a DECAT device, the thermal stabilizer section operative to reduce a temperature of the exhaust stream to 350° C. or less; and   treating the exhaust stream containing the reductant with a catalyst section of the DECAT device, the catalyst section including a base metal catalyst with an iron-containing zeolite catalyst augmented with cerium-manganese oxide (“IZCM catalyst”).   
     
     
         18 . The method of  claim 17 , wherein the exhaust stream containing the reductant is first treated with the thermal stabilizer section and subsequently treated with the catalyst section. 
     
     
         19 . The method of  claim 17 , further comprising maintaining the exhaust stream within a range of approximately 250° C. to 350° C. 
     
     
         20 . The method of  claim 17 , wherein treating the exhaust stream containing the reductant with a catalyst section includes substantially reducing VOC and HC. 
     
     
         21 . The method of  claim 17 , wherein treating the exhaust stream containing the reductant with a catalyst section includes catalytically reducing NOx. 
     
     
         22 . The method of  claim 17 , further comprising condensing VOC fractions of PM with at least one cooling device. 
     
     
         23 . The method of  claim 21 , wherein condensing VOC fractions of PM with at least one cooling device occurs before injecting the reductant. 
     
     
         24 . The method of  claim 17 , wherein the reductant is injected after the thermal stabilizer section and before the catalyst section. 
     
     
         25 . The diesel emissions control after-treatment system of  claim 1 , further comprising an iron-containing zeolite catalyst in the thermal stabilizer section. 
     
     
         26 . The diesel emissions control after-treatment system of  claim 25 , wherein the iron-containing zeolite catalyst facilitates SCR caused by exposure of the reductant to the iron.