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Cerium-based composite oxide catalyst for catalyzing and purifying nitric oxide

A composite oxide and nitrogen oxide technology, applied in metal/metal oxide/metal hydroxide catalysts, physical/chemical process catalysts, catalyst activation/preparation, etc., can solve the problem of narrow operating temperature window and sensitive reaction space velocity. , poor low temperature activity and other problems, to achieve the effect of improving service life, reducing damage, and good resistance to high temperature sintering

Active Publication Date: 2011-04-06
RES CENT FOR ECO ENVIRONMENTAL SCI THE CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In order to solve the problem of narrow operating temperature window, poor low-temperature activity, and N 2 Due to the shortcomings of low selectivity and sensitivity to reaction space velocity, the present invention provides a novel cerium-based composite oxide catalyst and its preparation method for the first time, which can be used as mobile sources represented by diesel vehicle exhaust and flue gas from coal-fired power plants. The representative stationary source NO x Catalytic purification

Method used

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  • Cerium-based composite oxide catalyst for catalyzing and purifying nitric oxide
  • Cerium-based composite oxide catalyst for catalyzing and purifying nitric oxide

Examples

Experimental program
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Effect test

Embodiment 1-4

[0016] Dissolve ammonium tungstate in oxalic acid solution (mass ratio of ammonium tungstate to oxalic acid is 1:1), and add cerium nitrate solution to the solution to prepare a solution with a Ce / W molar ratio of 0.5 and mix evenly. Add excess urea to the mixture, and continuously stir at 90°C for 12 hours, then perform suction filtration and washing, put the filter cake in an oven and dry it overnight at 100°C, and finally calcinate it in the air at 500°C in a muffle furnace for 5 hours. A powdered catalyst was obtained. The prepared catalyst was pressed into tablets, crushed, sieved, and 40-60 meshes were taken for later use, which was called catalyst A. Catalysts B and C were prepared respectively by changing the Ce / W molar ratio to 1.0 and 2.0 while other conditions remained unchanged. Catalyst D was prepared by calcining catalyst B in air at 800°C for 1 h.

Embodiment 5

[0018] With the cerium-tungsten composite oxide catalyst A, B, C and D that embodiment 1-4 makes, carry out NH on self-made miniature fixed-bed reactor 3 Selective Catalytic Reduction of NO x The investigation of reactivity. The consumption of catalyst is 0.12ml, and the composition of reaction gas mixture is: [NO]=[NH 3 ]=500ppm, [O 2 ] = 5%, N 2 As balance gas, the total gas flow rate is 500ml / min, and the space velocity is 250,000h -1 , The reaction temperature is 150-450°C. NO and NH 3 and by-product N 2 O, NO 2 All were measured using an infrared gas cell. The reaction results are shown in Table 1.

[0019] Catalyst B at 250,000h -1 Under the condition of space velocity, more than 80% NO can be achieved in the temperature range of 200-450°C x conversion rate, and at N 2 The selectivity is greater than 97%. Catalyst D calcined at 800°C can still be used at 250,000h -1 Under space velocity conditions, over 80% NO can be achieved within the temperature range of...

Embodiment 6

[0021] Using catalyst B, the effect of reaction space velocity on catalyst activity was investigated in a self-made miniature fixed-bed reactor. The consumption amount of catalyst is respectively 0.3ml, 0.12ml, 0.06ml, and the composition of reaction gas mixture is: [NO]=[NH 3 ]=500ppm, [O 2 ] = 5%, N 2 As balance gas, the total gas flow rate is 500ml / min, and the corresponding space velocity is 100,000h -1 、250,000h -1 , 500,000h -1 , Reaction temperature 150 ~ 450 ℃. NO and NH 3 and by-product N 2 O, NO 2 All were measured using an infrared gas cell. The reaction results are shown in Table 2.

[0022] Catalyst B at a space velocity of 100,000h -1 Under certain conditions, more than 98% of NO can be achieved in the temperature range of 200-450°C x conversion rate, and N 2 The generation selectivity is greater than 98%, showing a very wide operating temperature window; even at 500,000h -1 Under the condition of high space velocity, Catalyst B can still achieve mor...

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Abstract

The invention relates to a cerium-based composite oxide catalyst for ammonia selective catalytic reduction of nitric oxide and a preparation method thereof. The catalyst of the invention is a metal composite oxide catalyst comprising any one or more transition metals of cerium, tungsten, molybdenum and ferrum. The preparation method of the catalyst is an even precipitating method and comprises the following steps of: preparing the needed cerium salt and salt corresponding to any one or more transition metals into a mixed solution; with excessive urea as a precipitant, continuously stirring for 8-15 hours under the condition of the temperature of 90-95 DEG C; and then sucking for filtering, washing, drying and calcining to obtain the cerium-based composite oxide catalyst. In the invention, the cerium-based composite oxide catalyst which has the characteristics of high catalytic activity, excellent N2 generating selectivity, wide operating temperature window, adaption of high-air speed reaction condition, and the like is prepared by adopting a non-toxic and harmless raw material through a simple and easy method, and the cerium-based composite catalyst is suitable for a moving source nitric oxide catalytic purification device represented by the tail gas of a diesel vehicle and a fixed source nitric oxide catalytic purification device represented by the smoke of a coal fired power plant.

Description

technical field [0001] The invention is applied to the technical field of environmental catalysis, and relates to a cerium-based composite oxide catalyst used for catalytic purification of nitrogen oxides from mobile sources represented by diesel vehicle exhaust and stationary sources represented by flue gas from coal-fired power plants. Background technique [0002] Nitrogen oxides (NO x , mainly referring to NO and NO 2 ) will cause major environmental problems such as photochemical smog, acid rain, greenhouse effect and ozone layer depletion, and at the same time have biological respiratory toxicity, which can cause great harm to the ecological environment and human health. Therefore, how to effectively remove NO x It has become a hot issue in the field of environmental protection today. [0003] With the increasing shortage of oil resources, CO 2 The pressure to reduce emissions is increasing, and more and more attention has been paid to diesel vehicles with good fue...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/30B01J23/888B01D53/94B01D53/86B01D53/56
CPCB01D53/9418B01D2255/20769Y02T10/24B01D2255/2065B01D2255/40B01D2251/2062B01D2255/20776B01D2251/202B01D2255/20738B01J37/031B01J37/038B01J23/002B01J23/10B01J23/881B01J23/888B01J23/8885B01J37/0009B01J2523/00B01J23/28B01J23/30B01J23/83Y02A50/20Y02T10/12B01J35/56B01J2523/3712B01J2523/68B01J2523/69B01J2523/842B01D53/565
Inventor 贺泓单文坡刘福东石晓燕张长斌王少莘
Owner RES CENT FOR ECO ENVIRONMENTAL SCI THE CHINESE ACAD OF SCI
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