Fuel-lean vehicular engine exhaust gas catalyzing and purifying method

A vehicle engine and catalytic purification technology, which is applied to combustion engines, internal combustion piston engines, chemical instruments and methods, etc., can solve the problems of far-flung practical requirements, poor selectivity and high active temperature, and achieves widening the active temperature range, The effect of reducing dosage and improving NOx conversion rate

Inactive Publication Date: 2003-11-12
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These catalysts all have a certain NO reduction activity. However, when only relying on a single main active component catalyst and no additional reducing agent is added, the NO reduction activity temperature range is narrow, which is not compatible with the wide temperature range of the exhaust gas of the vehicle engine.
In addition, for supported noble metal catalysts, there are also poor selectivity, significant amount of NO being reduced to the greenhouse gas N 2 O; for metal ion-exchanged zeolite catalysts, there are still poor hydrothermal stability; for metal oxide catalysts, there are also problems such as the activation temperature is higher than the main exhaust temperature range of lean-burn vehicle engi

Method used

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  • Fuel-lean vehicular engine exhaust gas catalyzing and purifying method
  • Fuel-lean vehicular engine exhaust gas catalyzing and purifying method

Examples

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Example Embodiment

[0021] Example 1

[0022] Simulated lean-burn vehicle engine exhaust consists of 1000ppm NO, 1000ppm C 3 H 6 , 3000ppm CO, 8%O 2 , 1%H 2 O, 100ppm SO 2 and N 2 composition, plus the reducing agent is CH 3 OH at a concentration of 2200 ppm. Combined catalyst made of Ag / Al 2 O 3 and Pt / Al 2 O 3 In series composition, both catalysts were prepared by sol-gel mixing method, and the weight percentages of Ag and Pt were 5% and 2%, respectively. When the airspeed is 33,000h -1 , when the reaction temperature is 230-500 °C, the NOx conversion rate is higher than 60%, and above about 250 °C, HC and CO can be completely oxidized to CO 2 and H 2 O.

Example Embodiment

[0023] Example 2

[0024] Simulated lean-burn vehicle engine exhaust consists of 1000ppm NO, 1000ppm C 3 H 6 , 8%O 2 , 1%H 2 O, 100ppm SO 2 and N 2 composition, plus the reducing agent is C 2 H 5 OH at a concentration of 2300 ppm. Combined catalyst made of Ag / Al 2 O 3 and Pt / Al 2 O 3 In series composition, both catalysts were prepared by sol-gel mixing method, and the weight percentages of Ag and Pt were 5% and 2%, respectively. When the airspeed is 33,000h -1 , when the reaction temperature is 300-550 °C, the NOx conversion rate is higher than 60%, and at about 300 °C or more, HC can be completely oxidized.

Example Embodiment

[0025] Example 3

[0026] Simulated lean-burn vehicle engine exhaust consists of 1000ppm NO, 600ppm C 3 H 6 , 8%O 2 , 5000ppm CO, 1%H 2 O, 100ppm SO 2 and N 2 composition, plus the reducing agent is CH 3 OH at a concentration of 3500 ppm. Combined catalyst made of Sn / Al 2 O 3 and Pt / Al 2 O 3 In series composition, both catalysts were prepared by sol-gel mixing method, and the weight percentages of Sn and Pt were 5% and 2%, respectively. When the airspeed is 33,000h -1 , when the reaction temperature is 200-550 °C, the NOx conversion rate is higher than 60%, and above about 250 °C, HC and CO can be completely oxidized to CO 2 and H 2 O.

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Abstract

The invention is catalyst purifying method for tails discharged by fuel-lean car engine. The invention provides a method which applies to fuel-lean car engine, reduces NOx in tails efficiently in wide temperature range, and oxidizes HC and CO. The method includes following steps: sprays carbinol or alcohol into discharging pipe, and makes it blend with the engine tails; the mixed gas is transmitted to front grade catalyzing reaction bed which is loaded with transition metal oxide catalyst and the back grade catalyzing reaction bed which is loaded with laden noble metal catalyst, realizes the purification of NOx, HC and CO with high efficiency, and finally discharges normal gas. The invention can spread the range of NOx reduction active temperature.

Description

technical field [0001] Lean-burn refers to combustion under the condition of excess air. The invention relates to a catalytic purification method for exhaust gas of a lean-burn vehicle engine in which two catalysts are combined in stages as a catalyst system, and belongs to the technical field of catalytic purification of vehicle exhaust. Background technique [0002] At present, the mainstream technology for automobile exhaust purification is three-way catalytic conversion. This purification technology requires the engine to work under the condition of stoichiometric ratio. It is only applicable to gasoline engines, and to a certain extent, it is at the expense of fuel economy. . With the energy saving and reduction of greenhouse gas CO 2 With the increasing emphasis on emissions, the market prospect of lean-burn vehicle engines, including diesel engines and lean-burn gasoline engines, is getting wider and wider. The lean-burn method of gasoline or diesel-fueled vehicle e...

Claims

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Application Information

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IPC IPC(8): B01D53/94
CPCY02T10/24Y02T10/12
Inventor 朱天乐郝吉明傅立新王建昕李俊华刘志明崔翔宇
Owner TSINGHUA UNIV
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