Exhaust gas purification system and method for purifying exhaust gas

Abstract

An exhaust gas emitted from an engine (10) that contains nitrogen oxides is supplied to the cathode of a fuel cell (20), and a hydrogen-rich gas generated by the hydrogen gas generator (30) is supplied to the anode of the fuel cell (20). In the fuel cell (20), the nitrogen oxides are decomposed and electricity are generated by an electrochemical reaction between hydrogen and the nitrogen oxides. A hydrogen-separation membrane fuel cell, which operates at a temperature that is substantially the same temperature as that of the exhaust gas emitted from the engine (10) is used as the fuel cell (20).

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a system and a method for purifying exhaust gas, emitted from an internal combustion engine, that contains nitrogen oxides.[0003]2. Description of the Related Art[0004]Internal combustion engines are used as the driving power source for mobile conveyances such as vehicles. Typically, such internal combustion engines combust fuel and emit exhaust gases. These exhaust gases contain nitrogen oxides (NOx). Because nitrogen oxides pollute the atmosphere, they are usually removed by adsorption using an adsorbent or decomposed using a catalyst such as a NOx storage reduction catalyst or using plasma irradiation.[0005]Electrochemical processes have therefore been proposed to decompose nitrogen oxides. For example, Japanese Patent Application Publication No. 2001-70748 (hereinafter referred to as “JP-A-2001-70748”). describes process using a molten carbonate fuel cell to electrochemically decompo...

AI Technical Summary

Benefits of technology

The present invention provides a system and method for purifying exhaust gas from an internal combustion engine that contains nitrogen oxides without reducing energy efficiency or increasing system size. The system includes a fuel cell that operates at the temperature of the exhaust gas and uses nitrogen oxides as an oxidant gas and hydrogen as the fuel gas to generate electricity through an electrochemical reaction. The fuel cell includes a hydrogen-permeable metal layer and an electrolyte layer with proton-conductivity, making it possible to efficiently decompose nitrogen oxides while generating electricity. The system also includes a secondary battery for storing the electrical energy generated by the fuel cell. The method involves using the fuel cell to purify the exhaust gas and a mobile conveyance for installation of the system.

Problems solved by technology

Typically, such internal combustion engines combust fuel and emit exhaust gases.

It leads to a reduction in the energy efficiency of a system having the internal combustion engine, and an increase in the size of the system.

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