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Direct NOX decomposition catalyst with improved activity and selectivity

a technology of direct decomposition and catalyst, which is applied in the field of catalysts, can solve the problems of low activity and/or selectivity of catalysts for direct decomposition, and the inability to produce desirable products

Inactive Publication Date: 2019-03-14
TOYOTA JIDOSHA KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patent describes a new type of catalyst that can help remove nitrogen oxides from gases. The catalyst includes a special type of material called a CoFe2O4 spinel that has been doped with potassium ions. When this catalyst is exposed to a gas mixture containing nitrogen oxides, it can help catalyze the decomposition of the oxides into harmless nitrogen gas without needing any other chemicals. This technology may have various applications in reducing air pollution.

Problems solved by technology

Many catalysts for abating NO and NO2 (NO)) produce undesirable products, such as nitrous oxide (N2O) or ammonia.
Direct decomposition reactions, in which NOx is converted directly to N2 and O2 are known, but catalysts for direct decomposition frequently have low activity and / or selectivity, particularly at relevant temperatures in the low-to-mid hundreds of degrees Celsius.

Method used

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  • Direct NOX decomposition catalyst with improved activity and selectivity
  • Direct NOX decomposition catalyst with improved activity and selectivity
  • Direct NOX decomposition catalyst with improved activity and selectivity

Examples

Experimental program
Comparison scheme
Effect test

example 1

Synthesis of Examples 1-4 and the Comparative Example

[0048]CoFe2O4 is purchased from Sigma Aldrich and calcined at 400° C. for 1 hour. Examples 1-4 and the Comparative Example are synthesized by a wet impregnation synthesis procedure. In a wet impregnation, 5 g of CoFe2O4 are mixed with and suspended in 50 mL of water. A calculated quantity of potassium hydroxide, as shown below in Table 1, is dissolved separately in deionized water and combined with the CoFe2O4 suspension, and the mixture is heated to 80° C. with continuous stirring. The resulting powder is then dried in an oven at 120° C. for 12 hours under air. Finally, the catalyst is calcined at 400° C. for 1 hour in the presence of air after ramping up to 400° C. with a 1° C. / min ramp.

TABLE 1Composition of wet impregnation solutionsWeight %MassMassPotassium inCoFe2O4KOHdoped catalystComparative5 grams0mg0.0ExampleExample 15 grams36.06mg0.5Example 25 grams65.16mg0.9Example 35 grams108.2mg1.5Example 45 grams146.4mg2.0

example 2

Characterization of Examples 1-4 and the Comparative Example

[0049]The phase composition of Examples 1-4 and the Comparative Example is measured using X-ray diffraction measurements. X-ray powder diffraction (XRD) measurements are performed using a Rigaku SmartLab X Ray Diffractometer. Spectra are collected over a 20 range of 20-80 degrees at a rate of 0.5 degrees per minute with a step size of 0.02 degrees per step. Structural assignments are made using PDXL software. The phase composition of the materials is determined using the ICDD-PDF database.

[0050]Raman spectra of the samples are recorded using a HORIBA Lab Ram HR 800 spectrometer with a 532 nm Ar+ ion laser. Laser power is optimized to 0.5 milliwatts on the sample surface, after taking into consideration the (S / N) ratio and sample degradation. Raman spectra are acquired for 60s using a 100× objective lens.

[0051]NO adsorption capacities of the CoFe2O4 and K / CoFe2O4 catalysts are measured using NETZSCH STA-449 thermogravimetric...

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Abstract

A catalyst for direct decomposition of NO and NO2 to N2 and O2 has a CoFe2O4 spinel doped with potassium cations. The catalyst has high activity and good selectivity for N2 production, when potassium cations are loaded at a density of about 0.9 weight percent. Methods for making the catalyst include wet impregnation of a CoFe2O4 spinel with a solution of potassium cations, such as a KOH solution.

Description

TECHNICAL FIELD[0001]The present disclosure generally relates to catalysts for conversion of undesired components in a combustion exhaust and, more particularly, to catalysts for the direct decomposition of NOx.BACKGROUND[0002]The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it may be described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.[0003]Nitric oxide (NO) and nitrogen dioxide (NO2) are noxious components of combustion exhaust streams. Many catalysts for abating NO and NO2 (NO)) produce undesirable products, such as nitrous oxide (N2O) or ammonia. Direct decomposition reactions, in which NOx is converted directly to N2 and O2 are known, but catalysts for direct decomposition frequentl...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01J23/78B01J23/00B01J35/00B01J37/08B01J37/02B01D53/94F01N3/10
CPCB01J23/78B01J23/005B01J35/0013B01J37/08B01J37/0213B01J37/0209B01D53/9413F01N3/10B01D2255/405B01D2255/20738B01D2255/20746B01D2255/2022F01N2570/14B01J2523/00B01J37/0201B01J37/088Y02A50/20B01J35/40B01J35/23B01J2523/13B01J2523/842B01J2523/845
Inventor GUNUGUNURI, KRISHNAROBERTS, CHARLES ALEXANDER
Owner TOYOTA JIDOSHA KK
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