Poison-Resistant Catalyst and Systems Containing Same

Abstract

A poison-resistant catalytic converter includes a washcoat having a support material comprised of titania and/or silica and a plurality of platinum group metal particles disposed in the support material. The washcoat is disposed on a substrate having a plurality of cells that define respective apertures. The catalytic converter is resistant to poisoning from sulfur and phosphorous compounds while operating at low temperatures. Applications include spark ignited internal combustion engines in combined heat and power systems, vehicles, combustion turbines, boilers and other applications for utilities, industry and vehicle emissions control.

1 . A catalytic converter comprising:
 a substrate body having a plurality of cells that define respective apertures; and   a washcoat disposed on the substrate, the washcoat including:
 a support material comprised of support particles of at least one of titania or silica; and 
 a plurality of catalyst particles disposed in the support material, the catalyst particles comprised of a platinum group metal, the platinum group metal including at least one of Pt, Pd, and Rh, wherein the catalyst particles are substantially uniformly distributed in the support material. 
   
     
     
         2 . The catalytic converter of  claim 1 , wherein the support material further comprises a transition metal oxide. 
     
     
         3 . The catalytic converter of  claim 1 , wherein the support material further comprises a rare earth metal oxide. 
     
     
         4 . The catalytic converter of  claim 1 , wherein the support material comprises titania and the catalyst particles are comprised of at least one of Pt and Pd. 
     
     
         5 . The catalytic converter of  claim 4 , wherein the support material comprises 50% to 98% titania by weight. 
     
     
         6 . The catalytic converter of  claim 5 , wherein the support material comprises 10% to 50% of an oxide of at least one of Si, Al, Ce, Zr, Fe, Cu, Zn, Mo, W, and Mn. 
     
     
         7 . A method of manufacturing a poison-resistant catalyst that includes the catalytic converter of  claim 1 , the method comprising:
 milling a support material to form a powder-like substance, the support material containing at least 50% by weight of titania or silica;   mixing particles comprised of a platinum group metal into the milled support material to form a mixed milled support material;   forming a washcoat slurry from the mixed milled support material;   coating a substrate with the washcoat slurry, the substrate including a plurality of cells defining respective apertures;   drying the coated substrate at a first temperature to evaporate the washcoat slurry while reducing a sublimation of a liquid from a solid phase of the washcoat; and   after the drying act, calcining the coated substrate resulting in a poison-resistant catalyst that includes the catalytic converter of  claim 1 .   
     
     
         8 . The method of  claim 7 , wherein the coating act includes at least one of dose coating, curtain coating, and sequential washcoat coating. 
     
     
         9 . The method of  claim 7 , wherein the support material includes at least one of a transition metal oxide and a rare earth metal oxide. 
     
     
         10 . The method of  claim 7 , wherein the support material comprises titania and the platinum group metal includes Pt. 
     
     
         11 . A system for treating exhaust generated by a rich burn spark-ignited internal combustion engine, the system comprising:
 a first-stage catalyst chamber including a first three-way catalyst (TWC), the first-stage catalyst chamber in fluid communication with an exhaust outlet of the engine, the first stage catalyst chamber removing at least a portion of at least one of a NOx, a CO, or a hydrocarbon content in the exhaust to form a first output exhaust;   a cooling apparatus in fluid communication with an outlet of the first-stage catalyst chamber, the cooling apparatus configured to cool the first output exhaust to 300° F.-650° F., the cooling apparatus outputting a cooled exhaust;   an air injector in fluid communication with a conduit extending from an outlet of the cooling apparatus, the air injector configured to increase an oxygen content of the cooled exhaust to 0.25%-2.0% by volume;   a second-stage catalyst chamber including a poison-resistant catalyst, the second-stage catalyst chamber in fluid communication with the conduit to receive the cooled and oxygenated exhaust, the poison-resistant catalyst includes the catalytic converter of  claim 1 ,   wherein the second-stage catalyst chamber removes at least a portion of a CO content and a hydrocarbon content of the cooled exhaust.   
     
     
         12 . The system of  claim 11 , wherein the engine is a component of a combined heat and power system. 
     
     
         13 . The system of  claim 11 , wherein the engine is a component of a vehicle. 
     
     
         14 . The system of  claim 11 , wherein the support material further comprises a transition metal oxide. 
     
     
         15 . The system of  claim 11 , wherein the support material further comprises a rare earth metal oxide. 
     
     
         16 . The system of  claim 11 , wherein the support material comprises titania and the particles are comprised of at least one of Pt and Pd. 
     
     
         17 . The system of  claim 16 , wherein the support material comprises 50% to 98% titania by weight. 
     
     
         18 . The system of  claim 17 , wherein the support material comprises 10% to 50% of an oxide of at least one of Si, Al, Ce, Zr, Fe, Cu, Zn, Mo, W, and Mn. 
     
     
         19 . The system of  claim 11 , further comprising a thermoelectric generator disposed between the first-stage catalyst chamber and the second-stage catalyst chamber. 
     
     
         20 . The system of  claim 11 , wherein the cooling apparatus includes at least one of a water cooler, cooling coil, and a cooling vaporizer. 
     
     
         21 . The system of  claim 11 , wherein the second-stage catalytic converter removes at least a portion of a hazardous air pollutant content in the cooled exhaust. 
     
     
         22 . A method of operating a catalytic system for reducing emissions from a rich burn spark-ignited internal combustion engine, the method comprising:
 controlling a ratio of intake air and fuel (AFR) to the engine so the engine operates in a rich burn regime, the engine generating first exhaust gases substantially free of oxygen;   passing said first exhaust gases into a first-stage catalyst chamber to remove at least a portion of at least one of a NOx, a CO, or a hydrocarbon content in the first exhaust gases;   cooling said second exhaust gases to 300° F.-650° F.;   increasing an oxygen content of said second exhaust gases to about 0.25-2.0%; and   passing said cooled and oxygenated exhaust through a second-stage catalyst chamber containing a poison-resistant catalyst that reduces a CO content and a hydrocarbon content through oxidation reactions, wherein the poison-resistant catalyst includes the catalytic converter of  claim 1 .   
     
     
         23 . The method of  claim 22 , further comprising:
 exposing the poison-resistant catalyst for at least 500 hours to a compound including sulfur or phosphorous, the compound included in the cooled and oxygenated exhaust; and   maintaining a CO removal efficiency of the poison-resistant catalyst of at least 90% after the exposing act.   
     
     
         24 . The method of  claim 22 , further comprising operating a combined heat and power system that includes the engine that generates the exhaust. 
     
     
         25 . The method of  claim 22 , further comprising operating a vehicle that includes the engine that generates the exhaust. 
     
     
         26 . The method of  claim 22 , wherein the poison-resistant catalyst removes at least a portion of a hazardous air pollutant content in the cooled and oxygenated exhaust. 
     
     
         27 . A system for treating exhaust generated by a lean burn spark-ignited internal combustion engine, the system comprising:
 a cooling apparatus adapted to remove heat energy from the exhaust such that an input temperature of the exhaust is greater than an output temperature of the exhaust, the output temperature of the exhaust less than or equal to 650° F.; and   a catalytic converter including a poison-resistant catalyst, the catalytic converter in fluid communication with an output of the heat exchanger, the poison-resistant catalyst including the catalytic converter of  claim 1 ,   wherein the catalytic converter removes at least a portion of a CO content and a hydrocarbon content of the exhaust.   
     
     
         28 . The system of  claim 27 , wherein the engine is a component of a combustion turbine or a boiler. 
     
     
         29 . The system of  claim 27 , wherein the support material further comprises a transition metal oxide. 
     
     
         30 . The system of  claim 27 , wherein the support material further comprises a rare earth metal oxide. 
     
     
         31 . The system of  claim 27 , wherein the support material comprises titania and the particles are comprised of Pt and/or Pd. 
     
     
         32 . The system of  claim 31 , wherein the support material comprises 50% to 98% titania by weight. 
     
     
         33 . The system of  claim 32 , wherein the support material comprises 10% to 50% of an oxide of at least one of Si, Al, Ce, Zr, Fe, Cu, Zn, Mo, W, and Mn. 
     
     
         34 . The system of  claim 27 , wherein the cooling apparatus includes at least one of a heat exchanger, a water injector, an air injector, and cooling coils. 
     
     
         35 . The system of  claim 27 , wherein the poison-resistant catalyst removes at least a portion of a hazardous air pollutant content in the exhaust. 
     
     
         36 . A method of operating a catalytic system for reducing emissions from a lean burn spark-ignited internal combustion engine, the method comprising:
 controlling a ratio of intake air and fuel (AFR) to the engine so the engine operates in a lean burn regime;   with a cooling apparatus, cooling said second exhaust gases to less than or equal to 650° F.;   passing said cooled and oxygenated exhaust through a catalytic converter containing a poison-resistant catalyst that reduces a CO content and a hydrocarbon content of the exhaust, wherein the poison-resistant catalyst includes the catalytic converter of  claim 1 .   
     
     
         37 . The method of  claim 36 , further comprising:
 exposing the poison-resistant catalyst for at least 500 hours to a compound including sulfur or phosphorous, the compound included in the exhaust; and   maintaining a CO removal efficiency of the poison-resistant catalyst of at least 90% after the exposing act.   
     
     
         38 . The method of  claim 36 , further comprising operating a combustion generator that includes the engine that generates the exhaust. 
     
     
         39 . The method of  claim 36 , further comprising operating a boiler that includes the engine that generates the exhaust. 
     
     
         40 . The method of  claim 36 , wherein the poison-resistant catalyst removes at least a portion of a hazardous air pollutant content in the cooled and oxygenated exhaust.