Patent Application
20160136619
N/A
1. Field of the Disclosure
The present disclosure may provide Zero-PGM (ZPGM) catalyst materials, which may include stoichiometric or non-stoichiometric Co containing bimetallic spinel in the form of powder to use for three-way catalyst (TWC) applications.
2. Background Information
Air pollutants, such as NOx, CO, and HC from automobile exhaust should be removed as completely as possible from the combustion exit gases to avoid burdening the environment. Whereas power plant or motor vehicle emissions are being progressively curtailed with catalyst systems, there is a need for more effective Zero-PGM material compositions, capable of abating the pollutant fractions in motor vehicle exit of exhaust gases, which is becoming more important, especially with the increasing number of motor vehicles.
Many solutions have been proposed for catalyst conversion of NOx, CO, and HC emissions from motor vehicle engines. To diminish air pollutants levels. Catalyst materials may have to meet some catalyst requirements, including high conversion ratio at high and low temperatures, especially in the event of frequent load changes during operation, which is being accomplished by most of TWC systems.
TWC systems may include materials, which may be based on platinum group metals (PGMs), including Pt—Rh, Pt—Pd, Pd—Rh, among others, but may be desirable the use of cost effective material compositions for low manufacturing and operating costs, with high catalytic activities at all temperatures.
According to the foregoing reasons, there is a need of material compositions that does not require platinum group metals, and has similar o better efficiency as prior art catalysts, that can be used in a variety of environments for TWC applications, which can be manufactured cost-effectively. These materials may be capable to provide improved catalytic performance across a range of temperatures and operating conditions, while maintaining or even improving the catalytic activities under a variety of engine operating conditions.
The present disclosure may provide Zero-PGM (ZPGM) catalysts, which may include stoichiometric or non-stoichiometric variations of binary spinel systems including Co in its composition, on doped Zirconia support oxide in the form of powder, to develop suitable ZPGM catalysts for TWC applications.
According to embodiments in present disclosure, catalyst samples may be prepared using variations of Co—Cu, Co—Fe, and Co—Mn, stoichiometric and non-stoichiometric spinels on doped Zirconia support oxide, which may be converted into bulk powder format by incipient wetness (IW) method, as known in the art, of spinel systems aqueous solution on doped Zirconia support oxide powder. Stoichiometric or non-stoichiometric bimetallic spinel structures may be prepared at different molar ratios according to general formulation AXB3-XO4, where X may be variable of different molar ratios within a range from about zero to about 1.0. In present disclosure, disclosed Co—Cu, Co—Fe, and Co—Mn spinel systems may be supported on Praseodymium-Zirconia support oxide powders, which may be subsequently dried, calcined, and ground to fine bulk powder.
Disclosed binary spinel systems including Co—Cu, Co—Fe, and Co—Mn in its composition, may be verified preparing 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 bulk powder catalyst samples, per bimetallic spinel systems in present disclosure, may be determined by performing isothermal steady state sweep test. The isothermal steady state sweep test may be carried out 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 sweep test may be compared to show the influence that different bimetallic spinel system bulk powders may have on TWC performance, particularly under rich condition close to stoichiometric condition. Additionally, catalytic performance of bulk powder samples including Co—Cu, Co—Fe, and Co—Mn spinels may be qualitatively compared separately for each group of bimetallic spinel systems. According to principles in present disclosure, the bimetallic spinel system in each group, which shows high level of activity, may be compared with bimetallic spinel systems from other groups also showing high level of activity to analyze influence on TWC performance for overall improvements on catalyst systems.
According to principles in present disclosure, comparison of ZPGM bulk powder catalyst samples including Co in its composition for improved catalytic performance for a plurality of TWC applications. Catalyst samples in the other groups, which may show significant TWC performance, may also be made available for utilization as bulk powder catalyst materials for the manufacturing of ZPGM catalysts for TWC applications.
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.
“Milling” refers to the operation of breaking a solid material into a desired grain or particle size.
“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.
“Air/Fuel ratio” or “A/F ratio” refers to the weight of air divided by the weight of fuel.
“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 binary spinel bulk ZPGM powder material compositions including Co—Cu, Co—Fe and Co—Mn spinels, 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.
Bulk Powder ZPGM Catalyst Material Composition and Preparation
In the present disclosure, Zero-PGM material compositions in form of bulk powder may be prepared from stoichiometric and non-stoichiometric bimetallic spinels of Co—Cu, Co—Fe and Co—Mn at different molar ratios. All bimetallic spinels may be supported on doped Zirconia support oxide, via incipient wetness (IW) method as known in the art.
Preparation of bulk powder catalyst samples may begin by preparing the bimetallic solution for Co—Cu, Co—Fe and Co—Mn spinels to make aqueous precursor solution. Bimetallic solutions of Co—Cu, Co—Fe and Co—Mn spinels may be prepared by mixing the appropriate amount of nitrate precursors of two elements to obtain the right composition, including Co nitrate solution Co(NO3)2, Cu nitrate solution (CuNO3), Fe nitrate solution (Fe(NO3)3) or Mn nitrate solution (Mn(NO3)2). After mixing with water to make solution at different molar ratios, according to general formulations in Table 1, where disclosed bimetallic spinel systems in present disclosure are shown. Accordingly, solution of Cu—Co, Co—Fe, and Co—Mn nitrates may be subsequently added drop-wise to doped Zirconia powder via IW method. Then, mixtures of Cu—Co, Co—Fe, and Co—Mn bimetallic spinels on doped Zirconia support oxide may be dried at 120 C over night and calcined at about 800° C. for about 5 hours. Subsequently, calcined materials of Cu—Co, Co—Fe, and Co—Mn bimetallic spinels on doped Zirconia may be ground to fine grain bulk powder for preparation of catalyst samples.
Bulk powder catalyst samples may be prepared for testing under isothermal steady state sweep condition to determine and analyze TWC performance resulting for each catalyst sample including stoichiometric and non-stoichiometric Cu—Co, Co—Fe, and Co—Mn bimetallic spinels on doped Zirconia support oxide.
The NO/CO cross over R-value of bulk powder catalyst samples, per disclosed bimetallic spinels, may be determined by performing isothermal steady state sweep test.
Results from isothermal steady state sweep test may be compared to show the influence that different bimetallic spinel system bulk powders may have on TWC performance, particularly under rich condition close to stoichiometric condition at a selected R-value. Additionally, catalytic performance of bulk powder samples including stoichiometric and non-stoichiometric Cu—Co, Co—Fe, and Co—Mn spinels on doped Zirconia support oxide may be qualitatively compared.
According to principles in present disclosure, the bimetallic spinel system in each group, which shows high level of activity, may be compared with bimetallic 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 bulk powder catalyst materials to use ZPGM catalyst for TWC applications.
Isothermal Steady State Sweep Test Procedure
The isothermal steady state sweep test may be done employing a flow reactor at inlet temperature of about 450° C., and testing a gas stream at 11-point R-values from about 2.0 (rich condition) to about 0.8 (lean condition) to measure the CO, NO, and HC conversions. In present disclosure, gas stream may be tested at R-values from about 1.6 (rich condition) to about 0.9 (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 NOx, 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 may illustrate preparation of bulk powder catalyst samples from stoichiometric and non-stoichiometric Cu—Co spinels supported on Pr6O11—ZrO2 support oxide via IW method, according to a plurality of molar ratios, as shown in Table 2, based in general formulation CuxCo3-xO4, where X may be variable of different molar ratios within a range of about 0≦X≦1.
Preparation of bulk powder catalyst samples may begin by preparing the Cu—Co solution to make aqueous solution. Cu—Co solution may be prepared by mixing the appropriate amount of Cu nitrate solution (CuNO3) and Co nitrate solution Co(NO3)2 with water to make solution at different molar ratios according to formulation in Table 2, where disclosed stoichiometric and non-stoichiometric Cu—Co spinel systems are shown. Then, solution of Cu—Co nitrates may be added drop-wise to Pr6O11—ZrO2 support oxide powder via IW method. Subsequently, mixture of Cu—Co spinel 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.
In example #1, performance of bulk powder catalyst samples may be determined by performing isothermal steady state sweep test at about 450° C., and testing a gas stream at R-values from about 2.0 (rich condition) to about 0.8 (lean condition) to measure the CO, NO, and HC conversions. SV in the isothermal steady state sweep test may be adjusted at about 40,000 h−1. In present disclosure, NO conversion, CO conversion, and HC conversion from prepared bulk powder samples of stoichiometric and non-stoichiometric Cu—Mn spinels may be measured/analyzed from about 1.6 (rich condition) to about 0.9 (lean condition).
Catalytic Performance of Cu—Co Spinel Catalyst
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In
Example #2 may illustrate preparation of bulk powder catalyst samples from stoichiometric and non-stoichiometric Co—Fe spinels supported on Pr6O11—ZrO2 support oxide via IW method, with molar ratios according to formulation FexFCo3-xO4, where X may be variable of different molar ratios within a range of about 0≦X≦1.
Preparation of bulk powder catalyst samples may begin by preparing the Co—Fe solution to make aqueous solution. Co—Fe solution may be prepared by mixing the appropriate amount of Co nitrate solution Co(NO3)2 and Fe nitrate solution (Fe(NO3)3) with water to make solution at different molar ratios according to formulation in Table 3, where disclosed stoichiometric and non-stoichiometric Co—Fe spinel systems are shown. Then, solution of Co—Fe nitrates may be added drop-wise to Pr6O11—ZrO2 support oxide powder via IW method. Subsequently, mixture of Co—Fe spinel 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.
In example #2, the performance of bulk powder catalyst samples may be determined by performing isothermal steady state sweep test at about 450° C., and testing a gas stream at R-values from about 2.0 (rich condition) to about 0.8 (lean condition) to measure the CO, NO, and HC conversions. SV in the isothermal steady state sweep test may be adjusted at about 40,000 h−1. In present disclosure, NO conversion, CO conversion, and HC conversion from prepared bulk powder samples of stoichiometric and non-stoichiometric Co—Fe spinels may be measured/analyzed from about 1.6 (rich condition) to about 0.9 (lean condition).
Catalytic Performance of Fe—Co Spinel Catalyst
In
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May be observed in formula FexCo3-xO4 by increasing Co content (x<1.0), the NOx conversion activities decrease.
Example #3 may illustrate preparation of bulk powder catalyst samples from stoichiometric and non-stoichiometric Co—Mn spinels supported on Pr6O11—ZrO2 support oxide via IW method, with molar ratios according to formulation CoxMn3-xO4, where X may be variable of different molar ratios within a range of about 0≦X≦1.
Preparation of bulk powder catalyst samples may begin by preparing the Co—Mn solution to make aqueous solution. Co—Mn solution may be prepared by mixing the appropriate amount of Co nitrate solution Co(NO3)2 and Mn nitrate solution (Mn(NO3)2) with water to make solution at different molar ratios according to formulation in Table 4, where disclosed stoichiometric and non-stoichiometric Co—Mn spinel systems are shown. Then, solution of Co—Mn nitrates may be added to Pr6O11—ZrO2 support oxide powder via IW method. Subsequently, mixture of Co—Mn spinel 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.
In example #3, the performance of bulk powder catalyst samples may be determined by performing isothermal steady state sweep test at about 450° C., and testing a gas stream at R-values from about 2.0 (rich condition) to about 0.8 (lean condition) to measure the NO, CO, and HC conversions. SV in the isothermal steady state sweep test may be adjusted at about 40,000 h−1. In present disclosure, NO conversion, CO conversion, and HC conversion from prepared bulk powder samples of stoichiometric and non-stoichiometric Co—Mn spinels may be measured/analyzed from about 1.6 (rich condition) to about 0.9 (lean condition).
Catalytic Performance of Co—Mn Spinel Catalyst
In
As may be seen in
It may be noted an overall lower level of NOx conversion activity for Co1.0Mn2.0O4 spinel system. It may be also noted in CoxMn3-xO4, by increasing Mn, x<1.0, the NOx conversion activity decrease. However, there is an improved level of CO activities with 100% conversion, and also a good level of HC conversion activity for Co1.0Mn2.0O4 spinel system.
Bulk powder catalyst materials including stoichiometric and non-stoichiometric Co—Mn spinel may be employed as oxidation catalyst material for high level of HC/CO conversion.
Comparison of ZPGM catalyst performance for bimetallic systems with stoichiometric structure
In
In
In present disclosure, may be observed that stoichiometric and non-stoichiometric bimetallic Cobalt spinel systems not including Cu in its composition may show low or no NOx conversion activity. Cu may be the main element influencing improved NOx conversion. Additionally, in bimetallic systems including stoichiometric spinel formulation (A1.0B2.0O4) shows improved levels of catalytic activities than non-stoichiometric spinels, including all combinations of bimetallic spinel system.
Bulk powder catalyst materials, including stoichiometric and non-stoichiometric Co—Mn spinel may be employed as oxidation catalyst material for HC/CO activities. Also, bulk powder catalyst samples including stoichiometric Cu—Co spinel exhibits higher NOx conversion activities than bulk powder catalyst samples including non-stoichiometric Fe—Co and Mn—Co spinel. It may also be noted in present disclosure that CO conversion is about 100% for all disclosed stoichiometric and non-stoichiometric bimetallic spinel systems.
Bulk powder catalyst samples, including stoichiometric Cu—Co on Pr6O11—ZrO2 support oxide powder, may exhibit improved TWC performance activity when employed in ZPGM catalyst systems for a plurality of TWC applications, leading to a more effective utilization of ZPGM catalyst materials in TWC converters.
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.
