Ternary catalytic converter and method for coating catalytic layers thereof

Abstract

The invention relates to a ternary catalytic converter and a method for coating catalytic layers thereof. The ternary catalytic converter comprises a shell and a carrier arranged in the shell, wherein a catalytic layer I prepared by adopting a ternary catalyst I and a catalytic layer II prepared by adopting a ternary catalyst II are sequentially coated on the inner surface of the carrier from an air inlet to an air outlet; and the ternary catalyst II has the precious metal content being lower than that in the ternary catalyst I. Compared with the prior art, the ternary catalytic converter has the advantages that because the catalysts are coated in a partitioning manner, the structure is novel, the integral catalytic performance of the catalytic converter is increased, the catalytic conversion rate of the ternary catalytic converter during cold start is increased, the integral catalytic conversion rate of the ternary catalytic converter is increased, and the pertinence and the catalytic performance are strong; in addition, the method for coating the catalytic layers of the ternary catalyst is simple in process, can be used for ensuring the coating uniformity of the catalysts and is suitable for actual industrial production.

Description

technical field [0001] The invention relates to an engine exhaust gas purification technology, in particular to a three-way catalytic converter and a coating method for a catalytic layer thereof. Background technique [0002] The three-way catalytic converter is the most important external purification device installed in the automobile exhaust system. It can convert harmful gases such as CO, hydrocarbons (HC) and NOx in the exhaust gas from the automobile into harmless gases through oxidation and reduction. Harmful carbon dioxide, water and nitrogen. [0003] The three-way catalytic converter includes a shell and a carrier. The carrier is set in the shell. The carrier part is made of a piece of porous ceramic material, or it can be made into a honeycomb structure. The real function of the three-way catalytic converter is not the carrier itself, but the Catalyst material composed of platinum, palladium, rhodium and other precious metals covered on the carrier. The catalyti...

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Problems solved by technology

For example, the Chinese patent (authorized announcement number: CN201326446Y) discloses a carrier of a three-way catalytic converter, including a three-way catalytic converter and a carrier. The surface of the air inlet end of the carrier has a certain radius of curvature or a surface with a slope, and the catalyst Evenly coated on the inner surface of the carrier, although this method increases the exhaust gas processing capacity, it increases the contact area between the catalyst and the exhaust gas through the volume of the carrier to improve the exhaust gas processing capacity of the three-way catalytic converter. Relatively high, and the catalyst adopts the integral coating method, which requires a large amount of heat to make the catalyst fully reach the light-off temperature, which takes a long time to light-off, and the catalytic conversion efficiency is very low, which cannot solve the problem of three-way catalysis. The problem of the exhaust gas processing capacity when the engine is cold started

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