The special exhaust gas catalytic converter for CNG engine is composed of two parts, that are catalyst of honeycomb ceramics and metal shell, the main elements is: The exhaust gas pass through the catalyst of honeycomb ceramics, the active ingredient of catalyst (mostly are metal oxide of rare earths, precious metal and transitional metal) is able to carry out the catalysed reaction fully under the temperature condition of 200 to 300 celsius degree aboved converting the harmful element such as CO, HC, NOX etc. to innocuous water, carbon dioxide and nitrogen. a. key technique The core of this programm is the exhaust gas decontamination technique of CNG engine, which belongs to three-way decontamination catalyst technique, and is the main means of dealing with exhaust gas of CNG engine at present. The main chemical reaction formula as follows. This technique is the production jointly exploited by my company and professor Chen Shaoping from Nanchang university application chemical graduate school, it has following good characteristics: 1.Using honeycomb ceramics carrier that has many advantages, such as low cost, strong adhesive and active ingredient, long life etc. . 2.Adopting late-model of rare earths (material Zirconium and Titanium) to advance the heat resistance and activity of catalyst. 3.Introducing transitional metal, alkaline earth metal and active material of little precious metal that has plenty of excellences, such as high purification rate, and low burning temperature etc.. 4.Making use of new-style of oxygen storing stuff that reduces the burning temperature of catalyst and complete transformation. The catalytic converter applied and produced by this technique has past the test of Shanghai national exhaust gas test center and Tianjin university burning internal-combustion engine lab, the result indicates: using this cat that can make the emission standard reach European no.4 and meet the technique requirements the converter product demands. Oxidation reaction: HC+O2=H2O+CO2 Deoxidization reaction: NOx+HC+CO=N2