Catalyst for purifying tail gas of diesel automobiles, preparation method and purification device thereof

Abstract

The invention relates to a catalyst for purifying tail gas of diesel automobiles, a preparation method and a purification device thereof. The catalyst comprises a first carrier taking cordierite honeycomb ceramics as a matrix, and a second carrier taking SiC or a cordierite wall-flow structure as a matrix, a first coating and active components on the first carrier, as well as a second coating and active components on the second carrier. In the invention, coating, roasting and reduction processes are adopted for preparing the coatings composed of composite oxides. The catalyst and the device in the invention employ a technology combining a DOC (diesel oxidation converter) and a CDPF (catalyzed diesel particulate filter). By means of the DOC at a front end, HC, CO as well as the soluble organic fractions (SOF) in PM are removed through oxidation. Meanwhile, NO is converted to NO2 that has stronger reducibility so as to be good for the reaction of NO2 and C, thus reaching the purposes of removing NO and lowering the combustion temperature of C simultaneously. Depending on the self-temperatures of diesel automobiles to realize regeneration of a particulate filter, the purification device in the invention has the characteristics of high purification efficiency and convenient usage, etc.

Description

technical field [0001] The invention relates to a diesel automobile tail gas purification catalyst, a preparation method and a purification device. Background technique [0002] Diesel vehicle exhaust has a complex chemical composition, and with the change of engine operating conditions, the composition of exhaust gas is also significantly different. The pollutants emitted include soot particulate matter (PM), hydrocarbons (HC), CO and NOx, etc. Because of the O in the exhaust 2 The content is higher, so the HC and CO emissions are less, generally only 1 / 10 of gasoline engines, the NOx emissions are roughly the same as gasoline engines, and the PM emissions are about dozens of times that of gasoline engines. [0003] With the continuous expansion of the global production of passenger diesel vehicles, the exhaust emission of diesel vehicles has aroused widespread concern in the society. Especially since the implementation of Euro IV emission standards in 2005, the post-treat...

AI Technical Summary

Problems solved by technology

The common feature of these technologies is that the efficiency of the catalytic converter is high, but it is easily poisoned by sulfur, so it is necessary to use low-sulfur fuel and install sulfur adsorption and removal equipment

[0004] In recent years, positive progress has been made in the research of a single four-way purification catalyst in China. For example, the Eco-environmental Research Center of the Chinese Academy of Sciences has developed a 2 Selective removal of HC, CO and NO under atmosphere x The catalytic system mainly includes porous inorganic support and noble metals such as Pt, Au and Ag, etc., NO x The highest conversion rate is more than 90%, but the elimination of PM is very limited

China University of Petroleum (Patent No. 200710307416.8, titled: Combined Catalyst and Purification Method for Simultaneously Eliminating Four Diesel Engine Exhaust Pollutants) discloses a kind of Al 2 o 3 Loaded perovskite composite oxide La 0.8 K 0.2 MnO 3 Catalyst, the catalyst has good combustion activity for CO and carbon particles, the light-off temperature is significantly reduced, and CO is generated 2 The selectivity is higher than 95%, and the conversion rate of hydrocarbons at lower temperature is 90%, but the selective reduction of NO to N 2 Catalytic performance needs to be further improved

At present, the technology of domestic diesel vehicle exhaust purifier products is still relatively backward in general, and cannot meet the requirements of National IV and above diesel vehicle exhaust emission standards.

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