Abstract: A method of producing composite particles of titanium dioxide and a compound inactive as a photocatalyst, comprising the steps of preparing a water based slurry of pH 3 to 5 comprising titanium dioxide, preparing a water based solution comprising a compound inactive as a photocatalyst, and reacting the slurry and the water based solution together at a pH within a range from 4 to 10 is provided, together with highly active photocatalyst particles produced using such a method, and potential uses of such photocatalyst particles.

Abstract: The invention relates to a catalyst arrangement for purifying the exhaust gases of internal combustion engines operated under lean conditions. It is proposed that a thinwalled, porous carrier be coated on one side with a nitrogen oxide storage catalyst and on the other side with an SCR catalyst. When the exhaust gas is passed through the catalytic coatings and the support material, a significant improvement in the nitrogen oxide conversion is achieved compared to a series arrangement of the catalysts on separate carriers. Wall flow filters have been found to be useful as thin-walled carriers.

Abstract: In one embodiment, a reforming catalyst can include indium, tin, and a catalytically effective amount of a group VIII element for one or more reforming reactions. Typically, at least about 25%, by mole, of the indium is an In(3+) species based on the total moles of indium after exposure for about 30 minutes in an atmosphere including about 100% hydrogen, by mole, at a temperature of about 565° C. Usually, no more than about 25%, by mole, of the tin is a Sn(4+) species based on the total moles of tin after exposure for about 30 minutes in an atmosphere including about 100% hydrogen, by mole, at a temperature of about 565° C.

Abstract: A layered exhaust treatment catalyst comprising: (a) a carrier such as cordierite; (b) a first layer deposited on the carrier comprising a palladium metal component, a platinum metal component and an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina; and (c) a second layer deposited on the first layer comprising a rhodium metal component, a platinum metal component and an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina. Preferably, the catalyst also includes a bottom layer interposed between the carrier and the first layer. The bottom layer comprises an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina. The amount of the oxygen storage component of the catalyst may be “tuned”, i.e., adjusted, to meet the needs of a vehicle's on-board diagnostic (“OBD”) catalyst efficiency monitoring system, without adversely affecting the performance of the catalyst.

Abstract: The invention relates to a process for preparing a catalyst. The process allows the delamination of layered crystals which are used as a starting material for a catalyst. The starting material is subsequently converted into an active portion of a catalyst with an increased dispersion resulting in a higher activity. Preferred delaminating agents are di-carboxylic acids and one particular example is citric acid. Preferably at least 0.75 wt %, more preferably at least 1.5 wt % of a delaminating agent is added to the catalyst starting material.

Abstract: The present invention provides a zirconia-based mixed oxide which, together with improving the heat resistance of specific surface area at a high temperature (1000° C. for 3 hours), has a ceria reduction rate of 80% or more, or in other words, improves the heat resistance of specific surface area and the reduction rate of ceria. The zirconia-based mixed oxide has zirconia for the main component thereof and contains 5% or more of ceria and 1 to 30% of a rare earth metal oxide other than ceria, wherein the specific surface area after heat treating for 3 hours at 1000° C. is 50 m2/g or more, the reduction rate of the ceria contained in the mixed oxide is 80% or more, and preferably the specific surface area after heat treating for 3 hours at 1100° C. is 20 m2/g or more.

Abstract: An oxidation catalyst system is formed by particles of an oxidation catalyst dispersed in a porous sol-gel binder. The oxidation catalyst system can be applied by brush or spray painting while the sol-gel binder is in its sol state.

Abstract: Catalyst layers include an electrocatalyst having high oxygen reduction activity that is useful as an alternative material to platinum catalysts. Uses of the catalyst layers are also disclosed. A catalyst layer of the invention includes an electrode substrate and an electrocatalyst on the surface of the electrode substrate, and the electrocatalyst is formed of a metal compound obtained by hydrolyzing a metal salt or a metal complex.

Abstract: A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

Abstract: The present invention relates to a catalyst and to a process for preparing chlorine by catalytic oxidation of hydrogen chloride. The catalyst comprises an active component and a support material, said active component comprising at least uranium or a uranium compound. The catalyst is notable for a high stability and activity at a lower cost compared to the noble metals.

Abstract: A solid catalyst carrier substrate coated with a surface area-enhancing washcoat composition including a catalytic component, a metal oxide and a refractory fibrous or whisker-like material having an aspect ratio of length to thickness in excess of 5:1.

Abstract: A composition is based on zirconium oxide and cerium oxide with a proportion of zirconium oxide amounting to at least 50% by mass, having a maximum reducibility temperature of no more than 500° C. and a specific surface of at least 40 m2/g after 6 hours calcination at 500° C. in the form of a tetragonal phase. The composition can be used as a catalyst.

Abstract: A sorbent composition comprising a vanadium compound and a ZrO2 support material is disclosed. Methods of making and using the composition to remove heavy metals or heavy metal containing compounds from a fluid stream are also provided. Such methods are particularly useful in the removal of mercury and mercury compounds from flue gas streams produced from the combustion of hydrocarbon-containing materials such as coal and petroleum fuels.

Abstract: An exhaust emission control system can include a reformer a fuel source disposed upstream of and in fluid communication with the reformer, and a NOx adsorber disposed downstream of and in fluid communication with the reformer. The NOx adsorber can include a NOx adsorber catalyst having an acid adsorber disposed on the substrate and a base adsorber disposed over the acid adsorber.

Abstract: A promoted calcium-alumina supported reforming catalyst that is particularly useful for reforming reactions where low H2/CO ratio synthesis gas, such as less than 2.3 is generated directly is disclosed. The catalyst comprises from about 25 wt % to about 98 wt % alumina, from about 0.5 wt % to about 35 wt % calcium oxide, from about 0.01 wt % to about 35 wt % of a promoter, and from about 0.05 wt % to about 30 wt % of an active metal. The promoter is selected from the group consisting of titanium, zirconium, yttrium, niobium, elements of the lanthanum-series, such as, without limitation, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, ytterbium, and combinations thereof. The active metal is selected from the group consisting of nickel, cobalt, rhodium, ruthenium, palladium, platinum, iridium and combinations thereof as active metal, wherein the calcium oxide is combined with the alumina to form aluminum-rich calcium aluminates.

Abstract: A supported catalyst and a catalyst mixture, useful for the direct epoxidation of olefins, are disclosed. The supported catalyst comprises a noble metal, lead, and a carrier that has been treated by contacting with nitric acid. The catalyst mixture comprises a titanium or vanadium zeolite and the supported catalyst. The invention also includes a process for producing an epoxide comprising reacting an olefin, hydrogen and oxygen in the presence of the catalyst mixture. The process results in significantly reduced alkane byproduct formed by the hydrogenation of olefin.

Abstract: A method for producing a shell catalyst comprising a porous catalyst support shaped body with an outer shell containing at least one transition metal in metal form. To provide a shell catalyst with a relatively small shell thickness, a device is set up to circulate the catalyst support shaped bodies by means of process gases with a reductive effect. The device is charged with catalyst support shaped bodies that are circulated by means of a process gas with a reductive effect, an outer shell of the catalyst support shaped bodies is impregnated with a transition-metal precursor compound by spraying the circulating catalyst support shaped bodies with a solution containing the transition-metal precursor compound, the metal component of the transition-metal precursor compound is converted into the metal form by reduction by means of the process gas, and the catalyst support shaped bodies sprayed with the solution are dried.

Abstract: The present invention provides a photocatalyst material, which can comprise a photocatalyst with an excellent adherence to a substrate and a high photocatalytic activity, and a production method thereof. The photocatalyst material (20) obtained by reacting crystal nuclei with a sol solution containing an organic metallic compound or the like and then carrying out gelation, solidification and heat treatment has a structure where more than one basic structures (10) are fixed to the surface of the substrate (1). The basic structure consists of abase portion (2) comprising crystal nuclei fixed to the surface of the substrate (1) and a photocatalyst crystalline body (3), which connects to and is extended from the base portion (2) and has a columnar structure having a hollow portion (5) formed therein. A cylindrical substrate may be used for the substrate (1). The above photocatalytic activity is further enhanced by the formation of an interior-exposing structure (8) in a shell portion (4).

Abstract: Methods are disclosed herein for improving efficient catalyst utilization in processes including thermal catalysis using dry nanoparticle promoters, rather than salts of metal promoters in liquid form. Using selected process steps, the nanoparticles are more controllably dispersed on primary support particles, for effective use on secondary supports when it desired to bring reactants into contact with the secondary support. Applications that generally make use of these catalysts can be but are not limited to: emission abatement catalysts, generation of syngas, generation of liquid fuels from syngas, safety systems (hydrogen recombination catalysts in nuclear power plants) and many industrial processes.

Abstract: A photocatalytic device for reacting with volatile organic compounds includes a photocatalyst and at least one additive, such as hafnium oxide and zirconium oxide, that is capable of forming a stable silicate with silicon dioxide. The additive reacts with volatile silicon-containing compounds to form stable silicate compounds. As a result, the silicon-containing compounds are unavailable for deactivation of the photocatalyst.

Abstract: The present invention provides a catalyst having high activity and excellent stability, a process for preparation of the catalyst, a membrane electrode assembly, and a fuel cell. The catalyst of the present invention comprises an electronically conductive support and catalyst fine particles. The catalyst fine particles are supported on the support and are represented by the formula (1): PtuRuxGeyTz (1). In the formula, u, x, y and z mean 30 to 60 atm %, 20 to 50 atm %, 0.5 to 20 atm % and 0.5 to 40 atm %, respectively. When the element represented by T is Al, Si, Ni, W, Mo, V or C, the content of the T-element's atoms connected with oxygen bonds is not more than four times as large as that of the T-element's atoms connected with metal bonds on the basis of X-ray photoelectron spectrum (XPS) analysis.

Abstract: There is disclosed a photocatalyst which comprises a substrate having a photocatalytic function and metallic nanocolloid particles that are supported on the substrate by the use of a metallic nanocolloid liquid substantially free from a protective colloid formation agent. A highly active photocatalyst containing metallic ultrafine particles is provided by bringing a substrate such as fine particles having a photocatalytic function into contact with a metallic nanocolloid liquid which is substantially free from a protective colloid formation agent, and which has favorable dispersion stability even if containing metallic nanocolloid particles in a relatively high concentration. Accordingly the photocatalyst containing metallic ultrafine particles can be produced at a low cost without being restricted on the place of production.

Abstract: A layered, three-way conversion catalyst having the capability of simultaneously catalyzing the oxidation of hydrocarbons and carbon monoxide and the reduction of nitrogen oxides is disclosed. In one or more embodiments, the catalyst comprises three layers in conjunction with a carrier: a first layer deposited on the carrier and comprising palladium deposited on a refractory metal oxide and an oxygen storage component; a second layer deposited on the first layer and comprising rhodium deposited on a refractory metal oxide and an oxygen storage component; and a third layer deposited on the second layer and comprising palladium deposited on a refractory metal oxide.

Abstract: The present invention provides a process for preparing a supported catalyst (catalyst C) having a support (support S) selected from among oxides, phosphates, silicates, carbides, borides and nitrides of main group elements and elements of transition groups VI and II and mixtures of the abovementioned compounds and an active component (activator A) comprising one or more compounds containing one or more elements of transition groups V, VI and VII customary for the catalysis of metathesis reactions.

Abstract: The present invention relates to a trifunctional catalyst used in catalytic cracking device in petroleum refining industry and a method for preparing the same. The trifunctional catalyst of the invention comprises absorbent, cerium dioxide and vanadium pentoxide acting as oxidative catalyst and cerium oxyfluoride acting as structural promoter. The oxidative catalyst and structural promoter are dispersed over the absorbent. The absorbent is spinel-based composite oxides having a general formula of MgAl2-xFexO4.yMgO, where the x is 0.01-0.5 and y is 0.2-1.2. In the trifunctional catalyst, the raw material for forming the chemical compound containing rare-earth cerium is hamartite powder. The method for preparing the trifunctional catalyst of the invention is shown as follows: the components relating to the preparation of the finished product are dissolved or dispersed into liquid materials; then the trifunctional catalyst is obtained after the mixing, drying and calcining of such liquid materials.

Abstract: A catalyst for selective hydrogenation of acetylenes and diolefins, particularly in a raw gas feed stream for front end selective hydrogenation. The catalyst contains a low surface area carrier with a surface area from about 2-20 m2/g, wherein the pore volume of the pores of the carrier is greater than about 0.4 cc/g, at least 90 percent of the pore volume of the pores is contained within pores having a pore diameter greater than about 500 ? and about 1 to about 2 percent of the total pore volume is contained in pores with a pore diameter from about 500 to about 1,000 ?. The palladium comprises about 0.01 to about 0.1 weight % and a Group IB metal comprises about 0.005 to about 0.06 weight % of the catalyst.

Abstract: The present invention relates generally to catalysts comprising ruthenium oxide and to processes for catalyzing the oxidation and conversion of sulfur dioxide (SO2) to sulfur trioxide (SO3) using such catalysts. SO2 at low concentrations in process gas streams can be effectively oxidized to SO3 at relatively low temperatures using the ruthenium oxide catalysts of the present invention. In one application, the ruthenium oxide catalysts are used in the final contact stage for conversion of SO2 to SO3 in multiple stage catalytic converters used in sulfuric acid manufacture.

Abstract: A catalyst which efficiently removes particulate matter, SOF, sulfate, and SOOT and the like from the exhaust gas from such an internal combustion engine as a diesel engine without inducing a rise in the back pressure of the engine is provided. The catalyst for the purification of the exhaust gas of an internal combustion engine is formed by using an open flow honeycomb containing in the channel walls thereof such pores as possess an average diameter in the range of 10-40 ?m.

Abstract: This is to provide a catalyst for purifying exhaust gases, catalyst which are good in terms of the purifying performance.

Abstract: The formation of H2S in a stoichiometric or reducing atmosphere is restrained without using Ni or Cu as an environmental load substance. An additional oxide composed of an oxide of at least one kind of metal selected from the group consisting of Bi, Sn and Zn was added to a three-way catalyst for purifying an exhaust gas emitted from an internal combustion engine of which the combustion is controlled in near a stoichiometric atmosphere in the amount of from 0.02 mol to 0.2 mol per liter of the catalyst. The additional oxide forms SO3 or SO4 from SO2 in an oxidizing atmosphere, and stores sulfur components as a sulfide in a reducing atmosphere so that emission of H2S can be restrained. And since no environmental load substance is contained, the catalyst can be used safely.

Abstract: An aromatics hydrogenation catalyst composition which comprises a noble metal component and a support comprising zirconia, silica, and, optionally, alumina. The catalyst composition is manufactured by co-mulling silica, a zirconium compound, and, optionally, alumina to form a mixture that is formed into a shape, such as by extrusion to form an extrudate, with the shape being calcined and noble metal being incorporated into the shape. The catalyst composition may be used in the saturation of aromatic compounds.

Abstract: A catalyst for oxidation of unsaturated and/or saturated aldehyde to unsaturated acids is disclosed where the catalyst including at least molybdenum (Mo), phosphorus (P), vanadium (V), bismuth (Bi), and a first component selected from the group consisting of potassium (K), rubidium (Rb), cesium (Cs), thallium (Tl), or mixtures or combinations thereof, where the catalyst has at least 57% medium pores and a nitric acid to molybdenum mole ratio of at least 0.5:1 or at least 6.0:1 moles of HNO3 per mole of Mo12. Methods for making and using such catalysts are also disclosed.

Abstract: This invention relates to a catalyst material, and its method of making and manufacture, useful for a diversity of chemical production processes as well as various emission control processes. More specifically, it relates to a catalyst composition, preferably comprising a metal oxide felt substrate, with one or more functional surface active constituents integrated on and/or in the substrate surface, which can be used in the removal of sulfur and sulfur compounds from hot gases as well as acting to trap solid particulates and trace metals within these hot gases.

Abstract: An exhaust gas purging catalyst, includes: an integrated carrier; and a catalyst coat layer formed on the integrated carrier. The catalyst coat layer includes a catalyst component and meets the following expression (A): P?0.17W?0.04 - - - (A). P denotes a summation (ml) of a capacity of a void per mass (g) of the catalyst coat layer. The void has a pore diameter of 0.1 ?m to 1 ?m. W denotes a volume (ml) of the catalyst coat layer per the mass (g) of the catalyst coat layer.

Abstract: A photocatalytic device for reacting with volatile organic compounds includes a photocatalyst and at least one additive, such as hafnium oxide and zirconium oxide, that is capable of forming a stable silicate with silicon dioxide. The additive reacts with volatile silicon-containing compounds to form stable silicate compounds. As a result, the silicon-containing compounds are unavailable for deactivation of the photocatalyst.

Abstract: A method of producing catalyst powder of the present invention has a step of precipitating a transition metal particle and a base-metal compound in a reversed micelle substantially simultaneously, and a step of precipitating a noble metal particle in the reversed micelle. By this method, it is possible to obtain catalyst powder which restricts an aggregation of noble metal particles even at the high temperature and is excellent in the catalytic activity.

Abstract: The present invention provides a method for manufacture of supported noble metal based alloy catalysts with a high degree of alloying and a small crystallite size. The method is based on the use of polyol solvents as reaction medium and comprises of a two-step reduction process in the presence of a support material. In the first step, the first metal (M1=transition metal; e.g. Co, Cr, Ru) is activated by increasing the reaction temperature to 80 to 160° C. In the second step, the second metal (M2=noble metal; e.g. Pt, Pd, Au and mixtures thereof) is added and the slurry is heated to the boiling point of the polyol solvent in a range of 160 to 300° C. Due to this two-step method, an uniform reduction occurs, resulting in noble metal based catalysts with a high degree of alloying and a small crystallite size of less than 3 nm. Due to the high degree of alloying, the lattice constants are lowered.

Abstract: A method of producing a porous composite metal oxide comprising the steps of: dispersing first metal oxide powder, which is an aggregate of primary particles each with a diameter of not larger than 50 nm, in a dispersion medium by use of microbeads each with a diameter of not larger than 150 ?m, thus obtaining first metal oxide particles, which are 1 nm to 50 nm in average particle diameter, and not less than 80% by mass of which are not larger than 75 nm in diameter; dispersing and mixing up, in a dispersion medium, the first metal oxide particles and second metal oxide powder, which is an aggregate of primary particles each with a diameter of not larger than 50 nm, and which is not larger than 200 nm in average particle diameter, thus obtaining a homogeneously-dispersed solution in which the first metal oxide particles and second metal oxide particles are homogeneously dispersed; and drying the homogeneously-dispersed solution, thus obtaining a porous composite metal oxide.

Abstract: An improved skeletal iron catalyst is provided for use in Fischer-Tropsch synthesis reactions for converting CO and H2 to hydrocarbon products. The skeletal iron catalyst is manufactured using iron and a removable non-ferrous component such as aluminum. The iron and removable non-ferrous component are mixed together to form a precursor catalyst and then a portion of the removable non-ferrous component is removed to leave a skeletal iron catalyst. One or more first promoter metals and optionally one or more second promoter metals are incorporated into the skeletal iron catalyst either by blending the promoter into the precursor catalyst during the formation thereof or by depositing the promoter on the skeletal iron. The first promoter metals comprises a metal selected from the group consisting of titanium, zirconium, vanadium, cobalt, molybdenum, tungsten, and platinum-group metals.

Abstract: An engine exhaust catalyst exhibits improved CO oxidation performance relative to conventional engine exhaust catalysts and includes a first supported catalyst comprising platinum and a second supported catalyst comprising palladium and gold species in close contact. The first supported catalyst may be a platinum catalyst, a platinum—palladium catalyst, or a platinum catalyst promoted with bismuth, and the second supported catalyst preferably has a palladium to gold weight ratio of about 0.85:1.0. To improve aged catalyst performance, the first and second supported catalysts are coated onto different layers, zones, or monoliths of the substrate for the engine exhaust catalyst.

Abstract: A catalyst particle for use in growth of elongated nanostructures, such as e.g. nanowires, is provided. The catalyst particle comprises a catalyst compound for catalyzing growth of an elongated nanostructure comprising a nanostructure material without substantially dissolving in the nanostructure material and at least one dopant element for doping the elongated nanostructure during growth by substantially completely dissolving in the nanostructure material. A method for forming an elongated nanostructure, e.g. nanowire, on a substrate using the catalyst particle is also provided. The method allows controlling dopant concentration in the elongated nanostructures, e.g. nanowires, and allows elongated nanostructures with a low dopant concentration of lower than 1017 atoms/cm3 to be obtained.

Abstract: The present invention includes Fischer-Tropsch catalysts, reactions using Fischer-Tropsch catalysts, methods of making Fischer-Tropsch catalysts, processes of hydrogenating carbon monoxide, and fuels made using these processes. The invention provides the ability to hydrogenate carbon monoxide with low contact times, good conversion rates and low methane selectivities. In a preferred method, the catalyst is made using a metal foam support.

Abstract: The present invention relates to a novel method for preparing a catalyst for partial oxidation of methylbenzenes, comprising, (a) a step of preparing a solution or slurry of the compounds comprising tungsten; (b) a step of supporting the solution or slurry obtained in the step (a) on inorganic carrier; (c) a step of drying the catalyst obtained in the step (b); and (d) a step of calcining the dried catalyst obtained in the step (c), characterized in that the ratio of the pore volume of inorganic carrier and the volume of the solution or slurry in the step (b) is 1:0.9˜1.1, and the catalyst provides superior aromatic aldehydes selectivity to those prepared by the conventional impregnation or heat evaporation method over a wide range of conversion rate.

Abstract: Disclosed is an exhaust gas purifying catalyst, which comprises a CeZr-based composite oxide capable of maintaining a hollow structure to ensure an oxygen absorbing/releasing capability, even after being exposed to high-temperature exhaust gas. The exhaust gas purifying catalyst comprises a honeycomb-shaped substrate, and a catalyst layer formed on a surface of the substrate. The catalyst layer contains a composite oxide which includes cerium (Ce) and zirconium (Zr) and has a hollow structure, and a catalytic metal supported by the composite oxide. The composite oxide having the hollow structure includes, in a state after being subjected to a thermal aging in Air at 1000° C. for 24 hours, a particle with a shape having an outer diameter of 750 to 1000 nm and a shell thickness of 80 to 120 nm.

Abstract: An exhaust gas purification catalyst comprises: an oxygen storage component constituted by a mixed oxide containing cerium and zirconium; and a catalytic metal carried on the oxygen storage component. The oxygen storage component is in the form of hollow secondary particles each formed so that primary particles of an average particle size of less than 10 nm cohere into a shell.

Abstract: This invention relates to an organotin-based catalyst system for polyurethane synthesis that is useful in coatings applications. The catalyst has low activity in the absence of oxygen. When a coating mixture comprising the catalyst is sprayed and/or applied to a substrate as a thin film in air, the catalyst is activated. For solvent-based refinish systems comprising hydroxyl and isocyanate species at high solids levels, the catalyst system therefore provides extended viscosity stability, i.e., pot life.

Abstract: Provided herein are catalysts useful in reductive amination, which include nickel, copper, zirconium and/or chromium, oxygen, and tin. The presence of the tin increases the selectivity of the catalyst in reductive aminations over the catalysts of the prior art.

Abstract: The present invention provides a process for producing a gaseous product comprising hydrogen, said process comprising: contacting a feed gas mixture comprising steam and a gas comprising from 1 to 5 carbon atoms with a catalyst structure under reaction conditions sufficient to produce the product gas comprising hydrogen, wherein the catalyst structure comprises: a metal substrate comprising a metal; at least one layer of a catalyst support material coated onto the metal substrate, wherein the catalyst support material comprises: ?-alumina, zirconia, and at least one rare earth metal oxide; and at least one catalytically active component, wherein the at least one catalytically active component is incorporated either into or onto the catalyst support material.

Abstract: Catalyst comprising a combination of oxidized metals and processes for cleaving phenylalkyl hydroperoxides in the presence of the catalyst.

Abstract: This catalyst system simultaneously removes ammonia and enhances net NOx conversion by placing an NH3—SCR catalyst formulation downstream of a lean NOx trap. By doing so, the NH3—SCR catalyst adsorbs the ammonia from the upstream lean NOx trap generated during the rich pulses. The stored ammonia then reacts with the NOx emitted from the upstream lean NOx trap-enhancing the net NOx conversion rate significantly, while depleting the stored ammonia. By combining the lean NOx trap with the NH3—SCR catalyst, the system allows for the reduction or elimination of NH3 and NOx slip, reduction in NOx spikes and thus an improved net NOx conversion during lean and rich operation.