(JP4260441-A)      An exhaust gas purificn. catalyst is made of zeolite contg. cobalt and silver. Pref. a main component of hydrocarbon(s) in exhaust gas contains only 1 carbon. Purificn. process in which the catalyst is used; where a hydrocarbon (pref methane or a mixt gas mainly contg. methane) is pref added to the exhaust gas to be purified, is also claimed.    USE/ADVANTAGE -   Nitrogen oxide(s), carbon monoxide and hydrocarbon(s) can be removed from the exhaust gas contg. theses and an excess amt of oxygen, with high purificn. efficiency    (JP4363144-A)      Catalyst comprises Co and Pd-contg. zeolite. Purifying the waste gas comprises using catalyst; and preferably HC (especially methane) is added to waste gas.    USE/ADVANTAGE -   Removes NOx, CO and HC from combustion waste gas contg. excess oxygen. Even waste gas contg. methane (C=1) may be purified    (JP4363146-A)      Catalyst comprises Mn-contg. zeolite. Purifying waste gas comprises using catalyst.    Preferable HC, (CH), is added to the waste gas.    USE/ADVANTAGE -   Removes NOx, CO and HC from waste gas contg. excess O2. Even waste gas contg. CH4 (=1C HC) may be purified with higher efficiency    (EP499286-A3)      Catalysts comprise a zeolite contg. (i) Mn, (ii) Co and Pd, or (iii) Co and Ag. Zeolite is pref. ZSM-5. The metals may be introduced by impregnation or ion exchange. Pref. molar ratios are: (i) MnO/Al2O3 = 0.25-2; (ii) CoO/Al2O3 = 0.25-2, PdO/Al2O3 = 0.06-0.8, (PdO+CoO)/Al2O3 = 0.25-2.8; and (iii) CoO/Al2O3 = 0.6-1.45, Ag2O/Al2O3 = 0.05-1.45, (Ag2O+CoO)/Al2O3 = 0.6-5.5 Extra hydrocarbon may be added to the exhaust gas in an amt. of 50 ppm - 1%.    USE/ADVANTAGE -   High NOx conversions, even when the main hydrocarbon component is CH4, which has poor reducing properties (see also JA63-283727 and 1-130735%.    (US5407651-A)      Purifying an IC engine O2 rich exhaust gas by removing N oxides, CO and hydrocarbons from the gas, comprises contacting the gas with catalyst comprising a zeolite contg. Co and Pd or Co and Ag.    Pref., the hydrocarbons contain a IC hydrocarbon. At least 1 hydrocarbon is further added to the exhaust gas. The added hydrocarbon is methane or mixt. contg. methane. The hydrocarbon is added so that the content is 50 ppm to 1%, based on the exhaust gas.    ADVANTAGE -   N oxides, Co and hydrocarbons are efficiently removed.    (EP499286-B1)      A catalyst for purifying an exhaust gas to remove nitrogen oxides, carbon monoxide, and hydrocarbons from an exhaust gas containing the same as well as oxygen in an amount exceeding the amount of oxygen necessary for completely oxidizing reducing components such as carbon monoxide or hydrocarbons contained in the exhaust gas, the catalyst comprising a zeolite having (i) cobalt and palladium, or (ii) cobalt and silver contained therein, with the proviso that when the catalyst comprises a zeolite having cobalt and silver contained therein, alkaline earth metals are absent.    (JP3087320-B2)      Catalysts comprise a zeolite contg. (i) Mn, (ii) Co and Pd, or (iii) Co and Ag. Zeolite is pref. ZSM-5. The metals may be introduced by impregnation or ion exchange. Pref. molar ratios are: (i) MnO/Al2O3 = 0.25-2; (ii) CoO/Al2O3 = 0.25-2, PdO/Al2O3 = 0.06-0.8, (PdO+CoO)/Al2O3 = 0.25-2.8; and (iii) CoO/Al2O3 = 0.6-1.45, Ag2O/Al2O3 = 0.05-1.45, (Ag2O+CoO)/Al2O3 = 0.6-5.5 Extra hydrocarbon may be added to the exhaust gas in an amt. of 50 ppm - 1%.    USE/ADVANTAGE -   High NOx conversions, even when the main hydrocarbon component is CH4, which has poor reducing properties (see also JA63-283727 and 1-130735%.    (JP3087321-B2)      Catalysts comprise a zeolite contg. (i) Mn, (ii) Co and Pd, or (iii) Co and Ag. Zeolite is pref. ZSM-5. The metals may be introduced by impregnation or ion exchange. Pref. molar ratios are: (i) MnO/Al2O3 = 0.25-2; (ii) CoO/Al2O3 = 0.25-2, PdO/Al2O3 = 0.06-0.8, (PdO+CoO)/Al2O3 = 0.25-2.8; and (iii) CoO/Al2O3 = 0.6-1.45, Ag2O/Al2O3 = 0.05-1.45, (Ag2O+CoO)/Al2O3 = 0.6-5.5 Extra hydrocarbon may be added to the exhaust gas in an amt. of 50 ppm - 1%.    USE/ADVANTAGE -   High NOx conversions, even when the main hydrocarbon component is CH4, which has poor reducing properties (see also JA63-283727 and 1-130735%.    (JP3143936-B2)      Catalysts comprise a zeolite contg. (i) Mn, (ii) Co and Pd, or (iii) Co and Ag. Zeolite is pref. ZSM-5. The metals may be introduced by impregnation or ion exchange. Pref. molar ratios are: (i) MnO/Al2O3 = 0.25-2; (ii) CoO/Al2O3 = 0.25-2, PdO/Al2O3 = 0.06-0.8, (PdO+CoO)/Al2O3 = 0.25-2.8; and (iii) CoO/Al2O3 = 0.6-1.45, Ag2O/Al2O3 = 0.05-1.45, (Ag2O+CoO)/Al2O3 = 0.6-5.5 Extra hydrocarbon may be added to the exhaust gas in an amt. of 50 ppm - 1%.    USE/ADVANTAGE -   High NOx conversions, even when the main hydrocarbon component is CH4, which has poor reducing properties (see also JA63-283727 and 1-130735%.