Patent Application
20160167023
1. Field of the Disclosure
The present disclosure may provide Zero-PGM (ZPGM) catalyst materials, which may include stoichiometric or non-stoichiometric Co_Mn—Fe and Cu—Mn—Fe spinels in the form of fine grain powder to use for three-way catalyst (TWC) applications.
2. Background Information
TWC converters exhibit good catalytic activities and long life, which may be produced by combinations of noble metals using platinum group metals (PGM) materials. However, most TWC systems may present drawbacks of different natures. In some applications, these catalysts may operate at or near stoichiometric condition, and may not initiate the removal of toxic components included in exhaust gas until a relatively high temperature level is attained, and thus the catalyst may fail in removing/converting the toxic components at desired level of temperature from internal combustion engines.
Therefore, demand has emerged for material compositions and formulations capable of achieving the required TWC catalytic performance in a variety of environments, which are substantially free of PGM, because of its small market circulation volume, constant fluctuations in price, and constant risk to stable supply, amongst others.
According to the foregoing reasons, there is a need for catalyst material compositions that does not require platinum group metals, which are capable to achieve similar o better efficiency as prior art catalysts used for TWC applications. These materials may be able to provide improved catalytic performance across a range of temperatures and operating conditions, and can be manufactured cost-effectively.
The present disclosure may provide Zero-PGM (ZPGM) catalysts, which may include stoichiometric or non-stoichiometric Co_Mn—Fe and Cu—Mn—Fe spinels on doped Zirconia support oxide in the form of fine grain powder, to develop suitable ZPGM catalysts for TWC applications.
According to embodiments in present disclosure, a plurality of ternary ZPGM catalyst samples may be prepared using variations of Co—Fe—Mn and Cu_Fe—Mn spinels on doped Zirconia support oxide, which may be prepared by incipient wetness (IW) method or any other synthesis methods as known in the art. Stoichiometric or non-stoichiometric Co—Fe—Mn spinels may be prepared at different molar ratios according to formulation (CoxFezMn2z)3δO4 where Fe/Mn=0.5, x+3z=1, and 0≦δ≦0.2. In present disclosure, disclosed Co—Fe—Mn spinel systems may be supported on Praseodymium-Zirconia support oxide, which may be subsequently dried, calcined, and ground to fine grain bulk powder.
According to another embodiment in present disclosure, ternary ZPGM catalyst samples of disclosed Co_Mn—Fe on doped Zirconia support oxide, may be prepared by incipient wetness (IW) method or any other synthesis methods as known in the art. Stoichiometric or non-stoichiometric Co_Mn—Fe spinels may be prepared at different molar ratios according to formulation Co1-xMnxFe2O4 where 0≦x≦1. In present disclosure, disclosed Co_Mn—Fe spinel systems may be supported on Praseodymium-Zirconia support oxide, which may be subsequently dried, calcined, and ground to fine grain bulk powder.
According to another embodiment in present disclosure, ternary ZPGM catalyst samples of disclosed Cu—Mn—Fe on doped Zirconia support oxide, may be prepared by incipient wetness (IW) method or any other synthesis methods as known in the art. Stoichiometric or non-stoichiometric Cu—Mn—Fe spinels may be prepared at different molar ratios according to formulation CuxMnyFezO4 where x+y+z=3. In present disclosure, disclosed Cu—Mn—Fe spinel systems may be supported on Praseodymium-Zirconia support oxide, which may be subsequently dried, calcined, and ground to fine grain bulk powder.
Disclosed ternary catalyst systems including Co_Mn—Fe, and Cu_Fe—Mn spinels may be verified preparing fine grain bulk powder samples for each of the catalyst formulations and configurations, object of present disclosure, to determine its influence on TWC performance of ZPGM catalysts.
The NO/CO cross over R-value of prepared samples, per ternary spinel systems in present disclosure, may be determined and compared by performing isothermal steady state sweep test, which may be performed at a selected inlet temperature, using an 11-point R-value from rich condition to lean condition at a plurality of space velocities. Results from isothermal steady state test may be compared to show the effect that different ternary spinel system fine grain bulk powders may have on TWC performance, particularly under close to stoichiometric condition. Additionally, catalytic performance of fine grain bulk powder samples including Co—Fe—Mn spinel and Cu_Fe—Mn spinel may be qualitatively compared for each group of ternary spinel systems separately.
According to principles in present disclosure, fine grain bulk powder materials with compositions exhibiting a high level of catalytic activities, may be used for a plurality of TWC applications. From a catalyst manufacturer's viewpoint, may be an essential advantage, given the economic factors involved when substantially PGM-free materials are used for the manufacture of fine grain bulk powder catalyst materials capable to provide similar or improved TWC performance.
Numerous other aspects, features, and benefits of the present disclosure may be made apparent from the following detailed description taken together with the drawing figures, which may illustrate the embodiments of the present disclosure, incorporated herein for reference.
The present disclosure can be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being place upon illustrating the principles of the disclosure. In the figures, reference numerals designate corresponding parts throughout the different views.
The present disclosure is here described in detail with reference to embodiments illustrated in the drawings, which form a part here. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the present disclosure. The illustrative embodiments described in the detailed description are not meant to be limiting of the subject matter presented here.
As used here, the following terms may have the following definitions:
“Platinum group metal (PGM)” refers to platinum, palladium, ruthenium, iridium, osmium, and rhodium.
“Zero platinum group (ZPGM) catalyst” refers to a catalyst completely or substantially free of platinum group metals.
“Catalyst” refers to one or more materials that may be of use in the conversion of one or more other materials.
“Incipient wetness” refers to the process of adding solution of catalytic material to a dry support oxide powder until all pore volume of support oxide is filled out with solution and mixture goes slightly near saturation point.
“Calcination” refers to a thermal treatment process applied to solid materials, in presence of air, to bring about a thermal decomposition, phase transition, or removal of a volatile fraction at temperatures below the melting point of the solid materials.
“Treating, treated, or treatment” refers to drying, firing, heating, evaporating, calcining, or mixtures thereof.
“Spinel” refers to any of various mineral oxides of magnesium, iron, zinc, or manganese in combination with aluminum, chromium, copper or iron with AB2O4 structure.
“Conversion” refers to the chemical alteration of at least one material into one or more other materials.
“R-value” refers to the number obtained by dividing the reducing potential by the oxidizing potential of materials in a catalyst.
“Rich condition” refers to exhaust gas condition with an R-value above 1.
“Lean condition” refers to exhaust gas condition with an R-value below 1.
“Three-way catalyst (TWC)” refers to a catalyst that may achieve three simultaneous tasks: reduce nitrogen oxides to nitrogen and oxygen, oxidize carbon monoxide to carbon dioxide, and oxidize unburnt hydrocarbons to carbon dioxide and water.
The present disclosure provides a plurality of spinel fine grain bulk powder material compositions including Co_Mn—Fe spinel and Cu—Mn—Fe spinel, prepared at different molar ratios supported on doped-Zirconia support oxide, to develop suitable ZPGM catalyst materials capable of providing improved catalytic activities. Aspects that may be treated in present disclosure, may show improvements for overall catalytic conversion capacity for a plurality of ZPGM catalysts, which may be suitable for TWC applications.
Fine Grain Bulk Powder Catalyst Material Composition and Preparation
In the present disclosure, Zero-PGM material compositions in form of fine grain bulk powder may be prepared from stoichiometric and non-stoichiometric Co—Fe—Mn and Cu_Fe—Mn spinel compositions at different molar ratios, supported on doped Zirconia support oxide, via incipient wetness (IW) method as known in the art.
Preparation of fine grain bulk powder catalyst samples may begin by preparing the solution of Co—Fe—Mn or Cu_Fe—Mn spinels to make aqueous ZPGM solution of three metal precursors. Ternary solutions of Co—Fe—Mn or Cu_Fe—Mn spinels may be prepared by mixing the appropriate amount of Co nitrate solution Co(NO3)2, or Cu nitrate solution (Cu(NO3)2 with Fe nitrate solution (Fe(NO3)3) and Mn nitrate solution (Mn(NO3)2), with water to make solution at different molar ratios, according to general formulations in Table 1 or Table 2, where disclosed ternary spinel systems in present disclosure are shown. Accordingly, solution of metal nitrates may be subsequently added drop-wise to doped Zirconia powder via IW method. Then, mixtures of Co—Fe—Mn or Cu—Mn—Fe spinels on doped Zirconia support oxide may be dried and calcined at about 800° C. for about 5 hours. Subsequently, calcined materials of Co—Fe—Mn or Cu—Mn—Fe spinels on doped Zirconia may be ground to fine grain bulk powder for preparation of catalyst samples.
Bulk powder of ternary Co—Fe—Mn and Cu_Fe—Mn spinels on support oxide may be prepared via other synthesis methods known in the art, such as Co-precipitation, Impregnation, Sol-Gel method and any other methods used for preparation of powder samples.
Isothermal Steady State Sweep Test Procedure
The isothermal steady state sweep test may be carried out employing a flow reactor at inlet temperature of about 450° C., and testing a gas stream at 11-point R-values from about 2.00 (rich condition) to about 0.80 (lean condition) to measure the CO, NO, and HC conversions.
The space velocity (SV) in the isothermal steady state sweep test may be adjusted at about 40,000 h−1. The gas feed employed for the test may be a standard TWC gas composition, with variable O2 concentration in order to adjust R-value from rich condition to lean condition during testing. The standard TWC gas composition may include about 8,000 ppm of CO, about 400 ppm of C3H6, about 100 ppm of C3H8, about 1,000 ppm of NOR, about 2,000 ppm of H2, about 10% of CO2, and about 10% of H2O. The quantity of O2 in the gas mix may be varied to adjust Air/Fuel (A/F) ratio within the range of R-values to test the gas stream.
The following examples are intended to illustrate, but not to limit the scope of the present disclosure. It is to be understood that other procedures known to those skilled in the art may alternatively be used.
Example #1 describe preparation instructions of disclosed fine grain powder samples including Co—Fe—Mn spinels supported on doped ZrO2 support oxide via IW method, according to a plurality of molar ratios, as shown in Table 1, based in general formulation (CoxFezMn2z)3-δO4, where Fe/Mn=0.5, x+3z=1, and 0≦X≦0.2 supported on Pr6O11-ZrO2 support oxide, and general formulation Co1-xMnxFe2O4 spinel where 0≦X≦1 supported on Pr6O11-ZrO2 support oxide.
Example #1 may illustrate preparation of fine grain bulk powder catalyst samples including Co—Fe—Mn spinels supported on Pr6O11—ZrO2 support oxide via IW method.
Preparation of fine grain bulk powder catalyst samples may begin by preparing the Co—Fe—Mn solution by mixing the appropriated amount of Co nitrate solution Co(NO3)2, Fe nitrate solution (Fe(NO3)3) and Mn nitrate solution (Mn(NO3)2), with water to make solution at different molar ratios, according to general formulations in Table 1, where disclosed Co—Fe—Mn spinels are shown. Then, solution of Co, Fe, and Mn nitrates may be added drop-wise to Pr6O11—ZrO2 support oxide powder via IW method. Subsequently, mixture of Co, Fe, and Mn spinels on Pr6O11—ZrO2 support oxide may be dried at 120 C over night and calcined at about 800° C. for about 5 hours, and then ground to fine grain bulk powder for preparation of catalyst samples.
Results from isothermal steady state sweep test may be compared to show the influence that different ternary spinel system may have on TWC performance, particularly under rich condition close to stoichiometric condition. Additionally, catalytic performance of fine grain bulk powder samples including Co—Fe—Mn and Co_Mn—Fe spinels on doped Zirconia support oxide may be qualitatively compared.
According to principles in present disclosure, the ternary spinel system in each group, which shows high level of activity, may be compared with ternary spinel systems from other groups also showing high level of activity to analyze influence on TWC performance for overall improvements that may be developed in the preparation of fine grain bulk powder catalyst material to use for ZPGM catalyst for TWC applications.
Catalyst Performance for Co—Fe—Mn Spinel Catalyst
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Example #2 may illustrate preparation of fine grain bulk powder catalyst samples including Cu—Mn—Fe spinels supported on doped ZrO2 support oxide via IW method, with CuxMnyFezO4 formulation where x+y+z=3, according to a plurality of molar ratios, as shown in Table 2.
For preparation of fine grain bulk powder samples including each Cu_Fe—Mn spinel composition as shown in Table 2, a solution of corresponding spinel may be mixed with the appropriate amount of nitrate precursors of all elements. To get the right composition for each Cu_Fe—Mn spinel, mix the appropriated amount of nitrate precursor for all elements, including Cu nitrate solution (Cu(NO3)2, Fe nitrate (Fe(NO3)3) solution, and Mn nitrate solution (Mn(NO3)2), which may be mixed with water to make solutions at different molar ratios according to Table 2, where disclosed Cu_Fe—Mn spinels are shown. Then, solution of Cu, Fe, and Mn nitrates may be added to Pr6O11—ZrO2 support oxide powder via IW method. Subsequently, mixture of Cu, Fe, and Mn spinels on Pr6O11—ZrO2 support oxide may be dried at 120 C over night and calcined at about 800° C. for about 5 hours, and then ground to fine grain bulk powder for preparation of catalyst samples.
The NO/CO cross over R-value of prepared fine grain bulk powder samples, may be determined by performing isothermal steady state sweep test at inlet temperature of about 450° C., at TWC R values from about 1.60 (rich condition) to about 0.90 (lean condition), and SV of about 40,000 h−1, according to an embodiment.
Catalyst Performance for Cu_Fe—Mn Spinel Catalyst
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A comparison of test results indicates and verifies that samples including Cu1.0Fe1.0Mn1.0O4 and Cu1.0Fe0.5Mn1.5O4 spinel are more effective, exhibiting greater NOx conversion. Also may be observed that lower Fe content may increase NO conversion, operating at R-values of stoichiometric and non-stoichiometric condition, demonstrating better catalytic performance for TWC applications.
Performance Comparison for Co0.5Mn0.3Fe2.0O4 Spinel and Cu1.0Fe0.5Mn1.5O4 Spinel Catalysts
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A comparison of results of NOx, CO, and HC conversion, indicates and verifies that samples of Cu1.0Fe0.5Mn1.5O4 spinel shows an improved level of performance for TWC catalytic activities, and are more effective than Co_Mn—Fe spinel.
Fine grain bulk powder catalyst samples including Cu_Fe—Mn spinel and Co_Mn—Fe spinel, both supported on Pr6O11-ZrO2 support oxide, may have a positive effect and particularly useful for purifying exhaust gases produced by internal combustion engines, where lean/rich fluctuations in operating conditions may produce high variation in exhaust contaminants that may be removed, achieving improved catalytic activity performance under any operating conditions.
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.
