Nitrogen oxide decomposing element and nitrogen oxide decomposing apparatus including the same

Abstract

A nitrogen oxide decomposing element and a nitrogen oxide decomposing apparatus can perform a treatment at a relatively low temperature without using a material, which is suspected to have influence on the environment and human body, as an oxidant or a catalyst. There is proposed a nitrogen oxide decomposing element 1 including a conductive solid electrolyte film 2 for selectively allowing a hydrogen ion to pass through, a first electrode layer 3 made of an electronic conductivity base material and a catalyst for accelerating anodic oxidation, a second electrode layer 4 made of an electronic conductivity basematerialandacatalystforacceleratingcathodicreduction, and a platinum group catalyst 6 supported by a porous metal oxide 5 disposed to be adjacent to the second electrode layer 4. A low-power consumption nitrogen oxide decomposing apparatus which can efficiently use electric energy is obtained by locating a nitrogen oxide sensor 14 in the vicinity of the platinum group catalyst 6 supported by the metal oxide 5, and controlling the magnitude of a current flowing between the first and the second electrode layers 3 and 4 and the energization time by a power source / control device 15 in accordance with the concentration of nitrogen oxide detected by the nitrogen oxide sensor 14.

Description

TECHNICAL FIELD [0001] The present invention relates to a nitrogen oxide decomposing element for decomposing and removing nitrogen oxide and a nitrogen oxide decomposing apparatus including the same. BACKGROUND ART [0002] A nitrogen oxide purging system for decomposing and removing nitrogen oxide has various uses, such as an exhaust gas treatment of an automobile, a distributed cogeneration system, and air cleaning of an enclosed space such as a long tunnel or a factory, and increased demand is expected into the future. As a conventional technique to remove nitrogen oxide, for example, there is JP-A-2002-153755 as patent document 1. This patent document 1 discloses a method of purging nitrogen oxide NOx by using ammonia as a reductant. There is disclosed that in this method, an ammonia molecule (NH3molecule) donates an electron through an adjacent noble metal to nitrogen monoxide (NO) adsorbed on the noble metal, and as a result, the nitrogen monoxide (NO) becomes apt to dissociate ...

AI Technical Summary

Benefits of technology

[0009] Besides, a nitrogen oxide decomposing apparatus of the invention includes the nitrogen oxide decomposing element, a frame holding this, a gas supply ports for supplying an anode gas and a cathode gas into this frame, a gas exhaust port for exhausting the gases in the frame to outside, and a power source for applying a DC voltage between the first and the second electrodes.

[0008] According to the nitrogen oxide decomposing element of the invention, the nitrogen oxide decomposing element is obtained in which a treatment can be performed at a relatively low temperature (60° C. to 80° C.) without using a material, which is suspected to have influence on the environment and human body, as an oxidant or a catalyst.

Problems solved by technology

However, the method proposed in patent document 1 has problems that it is not desirable to use ammonia in consideration for the environment and human body, and further, it is necessary to perform the treatment at a high temperature of 400° C., it is difficult to perform the treatment adapted to variations in the concentration of nitrogen oxide, and the treatment of unreacted ammonia is required.

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