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Metal tungstates for use as nitrogen oxides reduction catalysts

Inactive Publication Date: 2016-05-05
TOYOTA MOTOR ENGINEERING & MANUFACTURING NORTH AMERICA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patent describes a new catalyst for reducing nitrogen oxides (NOx) in exhaust gases. The catalyst is made of a transition metal tungstate, specifically MWO4, where M can be Mn, Fe, Co, Ni, or Cu. The catalyst works effectively in reducing NOx in oxygen-rich environments with hydrocarbon fuel, but is also able to reduce NOx in oxygen-deficient environments. The process involves contacting a gas mixture containing nitrogen oxides and hydrocarbon fuel with the surface of the catalyst, resulting in the formation of nitrogen, water, and carbon dioxide. Overall, the patent provides a valuable tool for reducing NOx in exhaust gases.

Problems solved by technology

Exhaust from combustion engines creates nitrogen oxide (NOx) that contributes to smog and other forms of environmental pollution.
Further, prior art catalysts may have difficulty in reacting with NOx in the presence of oxygen.

Method used

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  • Metal tungstates for use as nitrogen oxides reduction catalysts
  • Metal tungstates for use as nitrogen oxides reduction catalysts
  • Metal tungstates for use as nitrogen oxides reduction catalysts

Examples

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Preparation of MWO4

[0037]Starting materials of Co(NO3)2, MnCl2, Fecl2, Ni(NO3)2 or Cu(SO4)4 and Na2WO4.2H2O were purchased from Sigma-Aldrich and used directly without further purification. In a typical synthesis a (0.2M) Na2WO4 solution was combined with a (0.2M) transition metal solution in a stoichiometric manner with strong agitation. The solution mixture was then placed into a glass microwave tube. A microwave assisted hydrothermal synthesis was conducted on a microwave reactor (Anton Paar Microwave 300). The microwave tube was heated to various temperatures at max power (800 W). The exposure to microwaves was maintained for various times as will be discussed in more detail below. Following the exposure to microwaves the tube was cooled by forced air flow. The resulting product was rinsed with DI water multiple times on a centrifuge followed by vacuum drying overnight at 60 degrees C. Following the drying step, the catalyst material was calcined in air at 550 degrees C. for 60...

example ii

Activity Testing MWO4

[0039]The activity testing was performed in a laboratory scale packed bed reactor (PID Eng&Tech Microactivity-Reference). Activity was determined for NO reduction by the hydrocarbon propylene (C3H6). Activity testing was performed under stoichiometric conditions both in oxygen deficient and oxygen rich conditions. As depicted in FIG. 3, under oxygen deficient conditions, the stoichiometric ratio of NO:C3H6 is 9:1, and under oxygen rich conditions, the stoichiometric ratio of NO:C3H6:O2 is 3:1:3. Also depicted in FIG. 3, 100 mg of catalyst material was combined with 400 mg of quartz sand and a total flowrate of 100 ml / min (gas hour space velocity GHSV˜15,000 inverse hours) was used for the testing in both oxygen rich and oxygen deficient conditions. A pretreatment phase includes heating the reactor and catalyst mixture to 500 degrees C. and maintaining the temperature for 15 minutes under oxidizing conditions (30 ml / min of 10% O2 in He balance). The reactor is t...

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Abstract

A nitrogen oxide (NOx) reduction catalyst that includes a transition metal tungstate having the formula: MWO4 wherein M is selected from the group consisting of Mn, Fe, Co, Ni, and Cu. The catalyst may be utilized in various environments including oxygen rich and oxygen deficient environments.

Description

FIELD OF THE INVENTION[0001]The invention relates to a catalyst for reducing nitrogen oxide (NOx) and to a process for reducing nitrogen oxide (NOx).BACKGROUND OF THE INVENTION[0002]Exhaust from combustion engines creates nitrogen oxide (NOx) that contributes to smog and other forms of environmental pollution. NOx should be removed from the exhaust streams of these engines in order to protect the environment and satisfy government regulations. Current 3-way catalyst converter technology may be used to remove NOx in automotive exhaust under certain limiting conditions. For example, 3-way catalysts operate at high temperatures greater than 300 degrees C. In addition, in order to meet current emissions standards, 3-way catalysts contain a large quantity of precious metals such as platinum, rhodium, and palladium. Further, prior art catalysts may have difficulty in reacting with NOx in the presence of oxygen.[0003]There is therefore a need in the art for an improved catalyst that reduce...

Claims

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Application Information

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IPC IPC(8): B01J23/888C01G53/00C01G51/00B01D53/94C01G41/02B01J35/02B01J23/34C01G49/00C01G45/12
CPCB01J23/888B01D2255/20761C01G53/40C01G51/40C01G45/12C01G41/02B01J35/023B01J23/34B01D53/945B01D2255/40B01D2255/20776B01D2255/2073B01D2255/20753B01D2255/20746B01D2255/20738C01G49/0018B01D53/9413B01J23/002C01G41/00C01G45/00C01G51/00C01G53/00C01P2004/03C01P2004/64C01P2006/12B01D2251/208B01J37/0238B01J37/10B01J37/346B01J35/30B01J35/612B01J35/40B01J35/613
Inventor JIA, HONGFEIROBERTS, CHARLES A.SAKANO, MITSURUMINAMI, KEIICHIPECK, TORINFANSON, PAUL T.
Owner TOYOTA MOTOR ENGINEERING & MANUFACTURING NORTH AMERICA