Abstract:
Variations of synthesis methods for Zero Platinum Group Metal (ZPGM) catalyst systems are disclosed herein. The methodologies of influence of synthesis methods on Cu—Mn catalyst systems which may include a variation of carrier metal oxides are disclosed. The XRD characterization and activity measurements of a series of stoichiometric and non-stoichiometric Cu—Mn spinels with different support oxide are discussed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    N/A 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    This disclosure relates generally to catalyst systems, and, more particularly, to variations resulting from synthesizing materials used in Zero Platinum Group Metal (ZPGM) catalyst systems. 
         [0004]    2. Background Information 
         [0005]    Regulatory standards for acceptable emissions may be continuously revised in response to human health issues and air-quality concerns. Said strict-compliance regulatory standards may have been adopted worldwide to control emissions of nitrogen oxides nitrogen (NO x ), particulate matters (PM), carbon monoxide (CO), and carbon dioxide (CO 2 ) from various sources, such as automobiles, utility plants, and processing and manufacturing plants amongst others. 
         [0006]    Catalysts to control toxic emissions may have a composite structure consisting of transition metal nano-particles or ions dispersed and supported on the surface of a support material. Said support materials may be either micro-particles with a very large specific surface area or a highly porous matrix. A requirement for the materials which may be used is that the catalyst may exhibit a very high level of heat resistance and be capable of ensuring stability and reliability in long-term service. 
         [0007]    Catalyst systems may be manufactured using platinum group metals (PGM) which may be characterized by a small market circulation volume, constant fluctuations in price, and constant risk to stable supply, variables that drive up their cost. These facts may be conducive to the realization of a PGM-free catalyst. 
         [0008]    For the foregoing reasons there may be a need to provide material compositions for PGM-free catalyst systems which may be able to perform in a variety of environments. Said catalyst systems may vary in a number of ways using synergistic effects derived from tools of catalyst design and synthesis methods. 
       SUMMARY 
       [0009]    The present disclosure may provide a methodology for synthesis of Cu—Mn ZPGM catalysts using different synthesis methods. 
         [0010]    Compositions of ZPGM catalyst systems may include any suitable combination of a substrate, a washcoat, an overcoat or impregnation component, which includes copper (Cu) and manganese (Mn) catalysts in combinations that are free of platinum group metals to form mixed phase of metal oxide and spinel catalysts. 
         [0011]    The desirable mixed phase systems may be affected by synthesis methods and type of carrier metal oxides. 
         [0012]    Synthesis methods that may be used to form stoichiometric and non-stoichiometric Cu—Mn spinel include co-precipitation, impregnation, co-milling, templating, colloidal, organometallic and sol-gel methods, or any other suitable methods known in the art. Subsequently, corresponding phase analyses may be determined by XRD measurement. Implemented synthesis methods for ZPGM Cu—Mn catalyst is compared according to the results from the effects of the synthesis method, type of supports, and type of Cu—Mn spinel and crystallite structure of mixed oxide phase. 
         [0013]    ZPGM Cu—Mn spinel catalyst maybe coated on a substrate by impregnation of the stabilized Cu—Mn spinel solution on a substrate previously washcoated, or by co-milling of Cu—Mn spinel solution with carrier material oxides and deposited on substrate. After deposition a heat treatment may be required. 
         [0014]    Numerous objects and advantages of the present disclosure may be apparent from the detailed description that follows and the drawings which illustrate the embodiments of the present disclosure, and which are incorporated herein by reference. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Non-limiting embodiments of the present disclosure are described by way of example with reference to the accompanying figures which are schematic and are not intended to be drawn to scale. Unless indicated as representing the background art, the figures represent aspects of the disclosure. 
           [0016]      FIG. 1  shows a ZPGM catalyst system configuration, according to an embodiment. 
           [0017]      FIG. 2  depicts a flowchart of templating method used to prepare ZPGM Cu—Mn catalyst system, according to an embodiment. 
           [0018]      FIG. 3  shows XRD analysis of a fresh and aged stoichiometric spinel of Cu 1.0 Mn 2.0 O 4 , according to an embodiment. 
           [0019]      FIG. 4  shows XRD analysis of a fresh stoichiometric spinel of Cu 1.0 Mn 2.0 O 4  after reaction, according to an embodiment. 
           [0020]      FIG. 5  shows XRD analysis of an aged stoichiometric spinel of Cu 1.0 Mn 20 O 4 , according to an embodiment. 
           [0021]      FIG. 6  illustrates crystallite size comparison of fresh Cu—Mn spinel catalysts, according to an embodiment. 
           [0022]      FIG. 7  illustrates CO light-off curves of variation of synthesis method with zirconium-niobium oxide support, according to an embodiment. 
           [0023]      FIG. 8  illustrates NO light-off curves of variation of synthesis method with zirconium-niobium oxide support, according to an embodiment. 
           [0024]      FIG. 9  illustrates CO light-off curves of variation of synthesis method with praseodymium doped zirconia support, according to an embodiment. 
           [0025]      FIG. 10  illustrates NO light-off curves of variation of synthesis method with praseodymium doped zirconia support, according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, which are not necessarily to scale or to proportion, similar symbols typically identify similar components, unless context dictates otherwise with emphasis being placed upon illustrating the principles of the invention. The illustrative embodiments described in the detailed description, drawings and claims, are not meant to be limiting. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of present disclosure. 
       Definitions 
       [0027]    As used here, the following terms have the following definitions: 
         [0028]    “R value” may refer to the number obtained by dividing the reducing potential by the oxidizing potential. 
         [0029]    “Rich exhaust” may refer to exhaust with an R value above 1. 
         [0030]    “Conversion” may refer to the chemical alteration of at least one material into one or more other materials. 
         [0031]    “Catalyst” may refer to one or more materials that may be of use in the conversion of one or more other materials. 
         [0032]    “Carrier material oxide (CMO)” may refer to support materials used for providing a surface for at least one catalyst. 
         [0033]    “Oxygen storage material (OSM)” may refer to a material able to take up oxygen from oxygen rich streams and able to release oxygen to oxygen deficient streams. 
         [0034]    “Washcoat” may refer to at least one coating including at least one oxide solid that may be deposited on a substrate. 
         [0035]    “Overcoat” may refer to at least one coating that may be deposited on at least one washcoat layer. 
         [0036]    “Zero platinum group (ZPGM) catalyst” may refer to a catalyst completely or substantially free of platinum group metals. 
         [0037]    “Synthesis method” may refer to an execution of chemical reactions to form a catalyst from different precursor materials. 
       DESCRIPTION OF THE DRAWINGS 
       [0038]    Catalyst System Configuration 
         [0039]      FIG. 1  depicts ZPGM Cu—Mn catalyst system  100  configuration of the present disclosure. As shown in  FIG. 1 , ZPGM Cu—Mn catalyst system  100  may include at least a substrate  102 , a washcoat  104 , and an overcoat  106 , where washcoat  104  and overcoat  106  may include Cu—Mn spinel ZPGM catalyst. 
         [0040]    In an embodiment of the present disclosure, substrate  102  materials may include a refractive material, a ceramic material, a honeycomb structure, a metallic material, a ceramic foam, a metallic foam, a reticulated foam, or suitable combinations, where substrate  102  may have a plurality of channels with suitable porosity. Porosity may vary according to the particular properties of substrate  102  materials. Additionally, the number of channels may vary depending upon substrate  102  used as is known in the art. The type and shape of a suitable substrate  102  would be apparent to one of ordinary skill in the art. 
         [0041]    According to an embodiment of the present disclosure, either washcoat  104  or overcoat  106  may include Cu—Mn spinel compound as ZPGM transition metal catalyst. Additionally, washcoat  104  and overcoat  106  may include support oxides material referred to as carrier material oxides. Carrier material oxides may include aluminum oxide, doped aluminum oxide, spinel, delafossite, lyonsite, garnet, perovksite, pyrochlore, doped ceria, fluorite, zirconium oxide, doped zirconia, titanium oxide, tin oxide, silicon dioxide, zeolite, and mixtures thereof. In the present embodiment, washcoat  104  and overcoat  106  may include oxygen storage materials (OSM), such as cerium, zirconium, lanthanum, yttrium, lanthanides, actinides, and mixtures thereof, but the catalysts of the present disclosure may be found to function well as oxidation/reduction catalysts without an OSM. 
         [0042]    Cu—Mn Spinel ZPGM Synthesis Methods 
         [0043]    A variety of synthesis methods may be implemented according to principles in the present disclosure. Synthesis methods that may be used include but are not limited to co-precipitation, impregnation, co-milling, templating, colloidal, organometallic and sol-gel methods. 
         [0044]    ZPGM Cu—Mn catalyst system  100  may be prepared by variety of synthesis methods, subsequently, corresponding phase analyses may be determined by XRD analysis. Implemented synthesis methods for ZPGM Cu—Mn catalyst system  100  may be compared according to catalysts prepared. Comparisons may be performed according to the results from the effects of the used synthesis method, type of supports, and type of spinel. XRD analyses and catalyst performance tests may be used to compare catalyst properties. 
         [0045]    Preparation of a ZPGM Catalyst by Co-Milling Method 
         [0046]    In order to prepare a ZPGM catalyst employing co-milling method, a catalyst and a carrier material oxide may be milled together. Co-milling process may begin with mixing washcoat  104  or overcoat  106  materials with water or any suitable organic solvent. Suitable organic solvents may include ethanol, diethyl ether, carbon tetrachloride, trichloroethylene, among others. Milling process in which washcoat  104  or overcoat  106  materials may be broken down into smaller particle sizes, may take about 10 minutes to about 10 hours, depending on the batch size, kind of material and particle size desired. The milling process may be achieved by employing any suitable mill such as vertical or horizontal mills. In order to measure exact particle size desired during the milling process, laser light diffraction equipment may be employed. After milling process, a catalyst aqueous slurry may be obtained. In order to enhance binding property washcoat  104  to substrate  102 , aqueous slurry obtained in milling process may undergo adjusting rheology, in which, acid or base solutions or various salts or organic compounds may be added to the aqueous slurry. Some examples of compounds that can be used to adjust the rheology may include ammonium hydroxide, aluminum hydroxide, acetic acid, citric acid, tetraethyl ammonium hydroxide, other tetralkyl ammonium salts, ammonium acetate, ammonium citrate, and other suitable compounds. The milled catalyst and carrier material oxide may be deposited on substrate  102  in the form of washcoat  104  or overcoat  106  and then treated separately. Washcoat  104  and overcoat  106  may be treated for about 2 hours to about 6 hours at a temperature within a range of about of 300° C. to about 700° C., preferably 550C. 
         [0047]    Preparation of a ZPGM Catalyst by Impregnation Method 
         [0048]    A ZPGM catalyst system includes substrate  102  and washcoat  104  and may include an impregnation component. Impregnation component includes the Cu—Mn ZPGM catalysts. Washcoat  104  may be deposited on substrate  102  and include carrier metal oxide and may include oxygen storage material. Washcoat  104  does not contain ZPGM catalyst. Washcoat  104  may prepared by any suitable chemical methods known in the art and treated after deposition on substrate  102 . The treating may be done at a temperature within a range of about 300° C. and about 700° C. and may last from about 2 to about 6 hours. After washcoat  104  and substrate  102  are treated, washcoat  104  may be cooled to about room temperature. After washcoat  104  and substrate  102  are cooled, washcoat  104  may be impregnated with Cu—Mn impregnation solution. The impregnation component may include copper and manganese salts being dissolved in water and impregnated on washcoat  104 . Following the impregnation step, washcoat  104  with the impregnation components may be treated. For example, treatment may be for about 4 hours at a temperature of about 550° C. Substrate  102 , washcoat  104 , and the impregnation components may be heat treated to form the catalyst composition after washcoat  104  and the impregnation components may be added to substrate  102 . 
         [0049]    Preparation of a ZPGM Catalyst by Sol-Gel Method 
         [0050]    Preparation of a ZPGM catalyst by sol-gel synthesis method may include hydrolysis, condensation-gelation, aging and drying. Preparation starts by hydrolysis of stoichiometric amount of copper and manganese precursors in aqueous solution. Typical Cu and Mn salt precursors that may be used include chlorides, nitrates, and acetates, as well as any other suitable precursors. In this synthesis method, the solution may gradually evolve into forming a gel-like system by adding the metal aqueous solutions to stabilizing component such as aqueous solution of ethylene glycol, citric acid, or glycolic acid. The pH and temperature need to be controlled in this synthesis method. Aging of this colloidal solution may be performed under continuous stirring at basic pH and temperature at the range of 60° C. to 90° C. to form the gel. The pH may be kept at range of 8 to 9 by adding ammonium hydroxide. Aging will last between 8 to 20 hours and remaining liquid may be removed during this step. Drying is performed at temperature between 100° C. to 120° C. overnight. Dried gel undergoes calcination treatment which may be for about 4 hours at a temperature of about 550° C. 
         [0051]    Preparation of ZPGM Cu—Mn Catalysts with Co—Precipitation Synthesis Method 
         [0052]    The preparation may begin by mixing the appropriate amount of Mn nitrate solution and Cu nitrate solution, where the suitable copper loadings may include loadings in a range of 10 to 20 percent by weight and suitable manganese loadings may include loadings in a range of 10 to 30 percent by weight. Subsequently, the Cu—Mn solution is mixed with slurry of carrier material oxide support. Co-precipitation method may be created by addition of appropriate amount of one or more of NaOH solution, Na 2 CO 3  solution, and ammonium hydroxide (NH 4 OH) solution. The pH of above slurry may be adjusted at the range of 7-9 and the slurry may be aged for a period of time of about 12 to 24 hours under continues stirring. This precipitation may be formed over a slurry including at least one suitable carrier material oxide, where the slurry may include any number of additional suitable carrier material oxides, and may include one or more suitable Oxygen Storage Materials. After precipitation, the metal oxide slurry may then undergo filtering and washing, where the resulting material may be dried and may later be calcined at any suitable temperature of about 300° C. to about 600° C., preferably about 500° C. for about 5 hours. 
         [0053]    Metal salt solutions suitable for use in the co-precipitation method described above may include solutions of copper nitrate (CuNO 3 ) or copper acetate and manganese nitrate (MnNO 3 ) or manganese acetate in any suitable solvent. 
         [0054]    Preparation of ZPGM Cu—Mn Catalysts with Templating Synthesis Method 
         [0055]      FIG. 2  depicts a flowchart of templating method  200  used to prepare ZPGM Cu—Mn catalyst system  100 , according to an embodiment. The preparation may begin by mixing step  202  the appropriate amount of Mn nitrate solution and Cu nitrate solution. Other copper and manganese precursors such as acetate may also be used. The Cu/(Cu+Mn) molar ratio may vary from 0.1 to 0.9 which results in stoichiometric and non-stoichiometric Cu—Mn spinels. For example, a molar ratio of 0.33 corresponds to stoichiometric Cu 1.0 Mn 2.0 O 4  and a molar ratio of 0.2 corresponds to non-stoichiometric Cu 0.6 Mn 2.4 O 4 . Subsequently, in templating step  204 , above solution is stabilized by a templating agent such as polyethylene glycol, polyvinyl alcohol, polyacrylic acid, poly-siloxane, oligosaccharides, poly( 4 -vinylpyridine), poly(N,Ndialkylcarbodiimide), hyper-branched aromatic polyamides and other suitable polymers. In present disclosure, poly(N-vinyl-2pyrrolidone)(PVP) is used as templating agent with a weight ratio of PVP to total weight of metal in the range of 0.5:1 to 2:1, preferably 1:1. Templating step  204  is done at room temperature and may last 24 hours and processing may continue with ions reduction step  206 , during which a NaBH 4  solution is added to reduce Cu—Mn ions to templated Cu—Mn particles. The NaBH 4  is added with a weight ratio of NaBH 4  to total metal in the range of 0.5:1 to 2:1, preferably 1:1. Subsequently, templated Cu—Mn particles may be aged at room temperature under continues stirring for 8 to 12 hours and then deposited on carrier metal oxide. Deposition on carrier metal oxide may be done as impregnation step  208  or any other deposition method known in the art, followed by drying step  210  and calcination step  212 . The templating agent component is decomposed at temperature below 550° C. for example 96% of PVP component may decompose up to 500° C. Carrier metal oxides may include cerium oxides, aluminum oxides, titanium oxides, doped aluminum oxides, doped ceria, zirconium oxides, doped zirconia, tin oxides, silicon dioxides, zeolite, and combinations thereof. In the present disclosure, carrier metal oxide for supported stoichiometric and non-stoichiometric spinels may include ZrO 2 —Nb 2 O 5  and ZrO 2 —Pr 6 O 11 . Catalysts containing Nb and Zr may promote the chemisorption of hydrocarbon by an acidic attack on the hydrocarbon double bond. In addition, catalysts containing Nb and Zr may exhibit resistance to SO 2  poisoning and may display enhanced oxidative properties and high permanent Broønsted acidity. 
         [0056]    In case of coating of ZPGM Cu—Mn spinel on substrate  102 , the stabilized Cu—Mn solution may be subsequently impregnated on washcoat  104 , or co-milled with carrier material oxides and deposited on substrate  102 . After deposition a heat treatment may be required. This treatment may be performed at about 300° C. to about 700° C. In some embodiments this treatment may be performed at about 550° C. The heat treatment may last from about 2 to about 6 hours. 
         [0057]    The following examples are intended to illustrate the scope of the disclosure. It is to be understood that other procedures known to those skilled in the art may alternatively be used. 
       Example #1 
     Co—Precipitation Method for ZPGM Cu—Mn Spinel Catalyst Systems 
       [0058]    Example #1 shows ZPGM Cu—Mn powder catalyst of the present disclosure which may be synthesized by co-precipitation method and may include precipitating of Cu—Mn stoichiometric spinels on one or more carrier material oxides. 
         [0059]    A ZPGM Cu—Mn powder catalyst, referred as SM1-Type 1, is a stoichiometric Cu 1.0 Mn 2.0 O 4 spinel, Cu—Mn molar ratio of 0.33, supported on ZrO 2 —Nb 2 O 5 . The carrier material oxide contains ZrO 2  from 60 to 80 percent by weight, preferably 75 percent by weight and Nb 2 O 5  from 20 to 40 percent by weight, preferably 25 percent by weight. A mixed phase of Cu—Mn spinel and CuO formed at fresh sample which undergoes calcination at 550° C. The Cu—Mn spinel phase is stable during aging at 900° C. The fresh SM1-Type1 catalyst may show a crystallite size of 11 nm and aged SM1-Type1 catalyst may show a crystallite size of 18 nm. 
         [0060]    A ZPGM Cu—Mn powder catalyst, referred as SM1-Type 2, is a stoichiometric Cu 1.0 Mn 2.0 O 4 spinel, Cu—Mn molar ratio of 0.33, supported on praseodymium doped zirconia (ZrO 2 —Pr 6 O 11 ). This carrier material oxide contains ZrO 2  from 80 to 95 percent by weight, preferably 90 percent by weight and Pr 6 O 11  from 5 to 20 percent by weight, preferably 10 percent by weight. A mixed metal oxide phase of CuO and MnO with crystallite size of 8 nm formed at fresh samples which undergoes calcination at 550° C. The evidence of formation of Cu—Mn spinel phase observed after aging SM1-Type 2 at 900° C. The aged SM1-Type 2 may show formation of a mixed metal oxide phase of Cu—Mn spinel, CuO, and Mn 3 O 4  with a crystallite size of 10 nm. 
       Example #2 
     Templating Method for Stoichiometric ZPGM Cu—Mn Spinel Catalyst Systems 
       [0061]    Example #2 shows ZPGM Cu—Mn powder catalyst of the present disclosure which may be synthesized by templating method  200  using PVP as stabilizer component. Cu—Mn stoichiometric spinels supported on one or more carrier material oxides may be synthesized by templating method  200 . 
         [0062]    A ZPGM Cu—Mn powder catalyst, referred as SM2-Type 1, is a stoichiometric spinel of Cu 1.0 Mn 2.0 O 4 , Cu—Mn molar ratio of 0.33, supported on ZrO 2 —Nb 2 O 5 . The carrier material oxide contains ZrO 2  from 60 to 80 percent by weight, preferably 75 percent by weight and Nb 2 O 5  from 20 to 40 percent by weight, preferably 25 percent by weight. A mixed phase of Cu—Mn spinel and CuO formed at fresh sample which undergoes calcination at 550° C. The Cu—Mn spinel phase is stable during aging at 900° C. The fresh SM2-Type1 catalyst may show a crystallite size of 9 nm and aged SM2-Type1 catalyst may show a crystallite size of 14 nm. SM2-Type1 catalyst may show improvement in particle size and therefore dispersion compare to SM1-Type1 catalyst because of type of synthesis method. 
         [0063]    A ZPGM Cu—Mn powder catalyst, referred as SM2-Type 2, is a stoichiometric spinel of Cu 1.0 Mn 2.0 O 4 , molar ratio of 0.33, supported on praseodymium doped zirconia (ZrO 2 —Pr 6 O 11 ). This carrier material oxide contains ZrO 2  from 80 to 95 percent by weight, preferably 90 percent by weight and Pr 6 O 11  from 5 to 20 percent by weight, preferably 10 percent by weight. A Cu 1.0 Mn 2.0 O 4  phase with crystallite size of  7  nm formed at fresh sample which undergoes calcination at 550° C. SM2-Type 2 shows improvement in formation of spinel phase in fresh sample compare to SM1-Type 2 catalyst because of the type of synthesis method. The Cu—Mn spinel phase is stable during aging at 900° C. A mixed oxide phase of Cu—Mn spinel, CuO and Mn 3 O 4  with crystallite size of 7 nm formed after aging SM2-Type 2 at 900° C. SM2-Type2 catalyst may show improvement in particle size and therefore dispersion compare to SM1-Type2 catalyst because of type of synthesis method. 
       Example #3 
     Templating Method for Non-Stoichiometric ZPGM Cu—Mn Spinel Catalyst Systems 
       [0064]    Example #3 shows ZPGM Cu—Mn powder catalyst of the present disclosure which may be synthesized by templating method  200  using PVP as stabilizer component. Cu—Mn non-stoichiometric spinels supported on one or more carrier material oxides may be synthesized by templating method  200 . 
         [0065]    A ZPGM Cu—Mn powder catalyst, referred as SM3-Type 1, is a non-stoichiometric spinel of Cu 0.6 Mn 2.4 O 4 , Cu—Mn molar ratio of 0.2, supported on ZrO 2 —Nb 2 O 5 . The carrier material oxide contains ZrO 2  from 60 to 80 percent by weight, preferably 75 percent by weight and Nb 2 O 5  from 20 to 40 percent by weight, preferably 25 percent by weight. A Cu 0.6 Mn 2.4 O 4  spinel phase formed at fresh sample which undergoes calcination at 550° C. The Cu—Mn spinel phase is stable during aging at 900° C. The fresh SM3-Type1 catalyst may show a crystallite size of 9 nm and aged SM3-Type1 catalyst may show a crystallite size of 14 nm. 
         [0066]    A ZPGM Cu—Mn powder catalyst, referred as SM3-Type 2, is a non-stoichiometric spinel of Cu 0.6 Mn 2.4 O 4 , Cu—Mn molar ratio of 0.2, supported on praseodymium doped zirconia (ZrO 2 —Pr 6 O 11 ). This carrier material oxide contains ZrO 2  from 80 to 95 percent by weight, preferably 90 percent by weight and Pr 6 O 11  from 5 to 20 percent by weight, preferably 10 percent by weight. A Cu 0.6 Mn 2.4 O 4 phase with crystallite size of 8 nm formed at fresh sample which undergoes calcination at 550° C. The Cu—Mn spinel phase is stable during aging at 900° C. A mixed oxide phase of Cu—Mn spinel, CuO and Mn 3 O 4  with crystallite size of 9 nm formed after aging SM3-Type 2 at 900° C. 
       Catalyst Characterization 
       [0067]    XRD measurements, comparisons, and performance for ZPGM Cu—Mn catalyst systems  100  which may be prepared by co-precipitation method and templating method  200 , according to various embodiments of present disclosure, as described in Example #1, Example #2 and Example #3 are disclosed. 
         [0068]    The XRD analysis is conducted to determine the phase structure Cu—Mn materials and to determine the crystallite size of mixed phase. The XRD patterns are measured on a Rigaku® powder diffractometer (MiniFlex™) using Cu Ka radiation in the 2-theta range of 15-80° with a step size of 0.02° and a dwell time of 1 s. The tube voltage and current were set at 40 kV and 30 rnA, respectively. The resulting diffraction patterns are analyzed using the International Centre for Diffraction Data (ICDD) database and crystallite sizes may be calculated by means of the Scherrer equation as known in the art. 
         [0069]    Catalyst activity of samples of stoichiometric Cu 1.0 Mn 2.0 O 4 spinels and non-stoichiometric Cu 0.6 Mn 2.4 O 4 spinels may depend on the chemical composition, type of Cu—Mn oxide phase, and degree of crystallinity. In the present disclosure, catalyst activity tests may be compared by light off curves under steady state condition. The gas composition is simulated under exhaust rich condition at an R-value of 1.224 and temperature increased from 100° C. to 600° C. with a rate of 20° C./min. Propylene (C 3 H 6 ) is used as feed hydrocarbon. 
         [0070]      FIG. 3  shows XRD analysis  300  of fresh and aged stoichiometric Cu 1.0 Mn 2.0 O 4  spinel supported on ZrO 2 —Nb 2 O 5 , as described in Example #2 and referred as SM2-Type 1. XRD spectrum  302  is for fresh sample of SM2-Type 1 and XRD spectrum  304  is for aged sample of SM2-Type 1. Solid lines correspond to Cu—Mn spinel phase and solid triangles refers CuO phase. The remaining diffraction peaks correspond to Nb 2 O 5  and ZrO 2  phases from support. Comparison of these two spectra shows the stability of oxide phases during aging, however, the aged sample of SM2-Type 1, XRD spectrum  302 , presents more crystallized structure after aging which is evidenced by sharper diffraction peaks. 
         [0071]      FIG. 4  shows XRD analysis  400 , after reaction (RXN) of a fresh stoichiometric Cu 1.0 Mn 2.0 O 4  spinel, supported on ZrO 2 —Nb 2 O 5 , as described in Example #2 and referred as SM2-Type 1. Fresh samples before and after reaction may be compared. As may be seen from XRD spectrum  302  and XRD spectrum  402 , similar pattern may be observed after RXN, which may mean that the Cu—Mn spinel phase may not change during RXN. However, new manganese oxide phase may form during reaction under rich condition. The solid line in  FIG. 4  corresponds to Mn 3 O 4  phase which only observed after RXN. 
         [0072]      FIG. 5  shows XRD analysis  500  of an aged stoichiometric Cu 1.0 Mn 2.0 O 4  spinel, supported on ZrO 2 -Pr 6 O 11 , as described in Example #2 and referred as SM2-Type 2. XRD analysis  500  of SM2-Type 2 shows formation of a mixed phase of Cu—Mn spinel (dot dash line), CuO phase (dash line) and Mn 3 O 4  (solid line). The remaining diffraction peaks corresponds to ZrO 2  from support. 
         [0073]      FIG. 6  illustrates crystallite size comparison  600  graphs of fresh Cu—Mn spinel catalysts explained in Example #1, Example #2 and Example #3. The crystallite size obtained by XRD measurements. The graphs compare the influence of synthetic method and choose of carrier metal oxide on crystallite size. SM1, SM2 and SM3 compare the synthesis method of co-precipitation of stoichiometric spinel, templating of stoichiometric spinel, and templating of non-stoichiometric spinel, respectively. Type 1 and Type 2 compare ZrO 2 —Nb 2 O 5  and ZrO 2 —Pr 6 O 11  metal oxide support, respectively. In general, templating method  200  leads to smaller crystallite size and therefore better metal dispersion. In addition, support effect shows decreasing of Cu—Mn crystallite size on ZrO 2 —Pr 6 O 11  compared to ZrO 2 —Nb 2 O 5 . 
         [0074]      FIG. 7  illustrates CO light-off  700  of Cu—Mn ZPGM powder catalysts prepared by different synthesis methods on ZrO 2 —Nb 2 O 5  support. CO light-off curve  702  shows CO conversion for a fresh stoichiometric Cu—Mn spinel of Example #1 prepared by co-precipitation method, SM1-Type 1. CO light-off curve  704  shows CO conversion for a fresh stoichiometric Cu—Mn spinel of Example #2 prepared by templating method  200 , SM2-Type 1. CO light-off curve  706  shows CO conversion for a fresh non-stoichiometric Cu—Mn spinel of Example #3 prepared by templating method  200 , SM3-Type 1. ZrO 2 —Nb 2 O 5  is used as support oxide for all samples. SM1-Type 1 may show better CO conversion response. Stoichiometric and non-stoichiometric Cu—Mn spinels, SM2-Type 1 and SM3-Type 1, show similar response to CO conversion under rich condition. Fresh SM1-Type 1, SM2-Type 1, and SM3-Type 1 shows T50 of CO at 185° C., 219° C. and 215° C., respectively. 
         [0075]      FIG. 8  illustrates performance in NO light-off  800  of Cu—Mn ZPGM powder catalysts prepared by different synthesis methods on ZrO 2 —Nb 2 O 5  support. NO light-off curve  802  shows NO conversion for a fresh stoichiometric Cu—Mn spinel of Example #1 prepared by co-precipitation method, SM1-Type 1. NO light-off curve  804  shows NO conversion for a fresh stoichiometric Cu—Mn spinel of Example #2 prepared by templating method  200 , SM2-Type 1. NO light-off curve  806  shows CO conversion for a fresh non-stoichiometric Cu—Mn spinel of Example #3 prepared by templating method  200 , SM3-Type 1. ZrO 2 —Nb 2 O 5  is used as support oxide for all samples. SM1-Type 1 may show better NO conversion response. Stoichiometric and non-stoichiometric Cu—Mn spinels, SM2-Type 1 and SM3-Type 1, show approximately similar response to NO conversion, especially at temperature above 400° C. Fresh SM1-Type 1, SM2-Type 1, and SM3-Type 1 shows T50 of NO at 375° C., 397° C. and 393° C., respectively. 
         [0076]      FIG. 9  illustrates CO light-off  900  of Cu—Mn ZPGM powder catalysts prepared by different synthesis methods on praseodymium doped ZrO 2  support. CO light-off curve  902  shows CO conversion for a fresh stoichiometric Cu—Mn spinel of Example #1 prepared by co-precipitation method, SM1-Type 2. CO light-off curve  904  shows CO conversion for a fresh stoichiometric Cu—Mn spinel of Example #2 prepared by templating method  200 , SM2-Type 2. CO light-off curve  906  shows CO conversion for a fresh non-stoichiometric Cu—Mn spinel of Example #3 prepared by templating method  200 , SM3-Type 2. ZrO 2 —Pr 6 O 11  is used as support oxide for all samples. SM1-Type 2 may show better CO conversion response under rich condition. Fresh SM1-Type 2, SM2-Type 2, and SM3-Type 2 shows T50 of CO at 187° C., 210° C. and 203° C., respectively. 
         [0077]      FIG. 10  illustrates performance in NO light-off  1000  of Cu—Mn ZPGM powder catalysts prepared by different synthesis methods on praseodymium doped ZrO 2  support. NO light-off curve  1002  shows NO conversion for a fresh stoichiometric Cu—Mn spinel of Example #1 prepared by co-precipitation method, SM1-Type 2. NO light-off curve  1004  shows NO conversion for a fresh stoichiometric Cu—Mn spinel of Example #2 prepared by templating method  200 , SM2-Type 2. NO light-off curve  1006  shows CO conversion for a fresh non-stoichiometric Cu—Mn spinel of Example #3 prepared by templating method  200 , SM3-Type 2. ZrO 2 —Pr 6 O 11  is used as support oxide for all samples. SM1-Type 2 may show lower NO conversion response. Stoichiometric and non-stoichiometric Cu—Mn spinels, SM2-Type 2 and SM3-Type 2, shows approximately similar response to NO conversion and significant improvement compare to SM1-Type 2. Fresh SM1-Type 2, SM2-Type 2, and SM3-Type 2 show T50 of NO at 450, 370 and 375 C, respectively. The formation of Cu—Mn spinel in fresh SM2-Type 2, and SM3-Type 2 is responsible for NO conversion improvement compare to mixed Cu and Mn oxide phase in fresh SM1-Type2. 
         [0078]    While various aspects and embodiments have been disclosed, other aspects and embodiments may be contemplated. The various aspects and embodiments disclosed here are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.