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Oxygen-enriched tail gas nitrogen oxide purifying catalyst

A catalyst and tail gas technology, applied in the direction of metal/metal oxide/metal hydroxide catalyst, physical/chemical process catalyst, chemical/physical process, etc., can solve the problem of poor selectivity of noble metal catalysts, loss of reduced nitrogen oxides, poisoning, etc. question

Inactive Publication Date: 2004-07-07
RES CENT FOR ECO ENVIRONMENTAL SCI THE CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the main problems of the catalysts under research are that zeolite catalysts are poisoned by water vapor and sulfur dioxide, and have poor hydrothermal stability; noble metal catalysts have poor selectivity, and the activity temperature range is narrow, and most of the reducing agents are oxidized and burned in the high temperature zone to lose reduced nitrogen. The ability of oxides; the low-temperature activity of supported metal or metal oxide catalysts needs to be improved when organic substances such as low-carbon olefins and alkanes are used as reducing agents
For example, we previously applied for a silver catalyst patent (application number: 02100669.5), which has good resistance to sulfur dioxide poisoning and hydrothermal stability, and can be used in the simulated tail gas temperature range of 400-550 ℃ with propylene as the reducing agent The average nitrogen oxide conversion rate is 57.7%, but the low-temperature activity of the silver catalyst is poor

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] 100 grams of gamma-alumina powder (particle size less than 120 mesh, specific surface area: not less than 250 square meters per gram) is soaked in the mixed aqueous solution of silver nitrate, platinum chloric acid and ferric nitrate at a predetermined concentration, stirred for 1 hour, After drying at 90°C, raise the temperature from 100°C to 700°C step by step in the air, keep it for 3 hours, and then cool it down to room temperature. After crushing, take 0.5-1.0mm particles for later use as catalyst A. The silver component load of the finished product catalyst is 5.0% (metal element weight conversion value), the platinum component load is 0.25% (metal element weight conversion value), and the iron component load is 15.0% (metal element weight conversion value). value).

Embodiment 2

[0019] 1.5 grams of implementation catalyst A and comparison catalyst A made by the above method are placed in the tubular reactor respectively, and 4 liters / min of simulated lean combustion tail gas as shown in table 1 are introduced, corresponding to space velocity (GHSV) 50,000 / hour. The temperature of the simulated tail gas entering the reactor was raised from 200°C to 600°C, and the reduction of nitrogen oxides by propylene was observed when the catalytic reaction reached a steady state.

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Abstract

A catalyst of removing the NOx, residual organic substance and CO from the oxygen-enriched tail gas from engine contains the porous inorganic carrier, silver, noble metal chosen from Au, Pt, Pd, Ph, Ir and Ru, and other metal chosen from Fe, Cu, Ti, Zr, Ba, Sn, W, Zn, Mo, Ce, Cs, La and Ca.

Description

technical field [0001] The invention is used for purifying nitrogen oxides in exhaust gas of an internal combustion engine, especially for selectively reducing nitrogen oxides with limited carbon monoxide and organic matter in an oxidizing atmosphere, and the catalyst also has higher nitrogen oxide reduction activity at a lower temperature. technical background [0002] This is different from the three-way catalyst currently commonly used to purify gasoline engine exhaust. The use of three-way catalysts is based on the strict control of the ratio of air to fuel in gasoline engines near the theoretical air-fuel ratio (stoichiometric ratio), at which point the remaining oxygen content in the exhaust gas is very small. Its mechanism of action is that carbon monoxide and organic matter are used as reducing agents to reduce nitrogen oxides (NO x ) into nitrogen, and catalytically oxidize the remaining carbon monoxide and organic matter into carbon dioxide and water. At present,...

Claims

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Application Information

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IPC IPC(8): B01D53/94B01J23/89
Inventor 贺泓冯庆彩王进张润铎
Owner RES CENT FOR ECO ENVIRONMENTAL SCI THE CHINESE ACAD OF SCI
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