摘要:
Exhaust gas purifying method and apparatus for internal combustion engines in which the temperature of an exhaust gas purifying catalyst is detected and, as desired, oxygen content of exhaust gas is further detected, and in which the actual air-fuel ratio is varied toward the higher air-fuel ratio side and the lower air-fuel ratio side with respect to the theoretical air-fuel ratio, in accordance with the frequency and amplitude preset dependent on the kind of the catalyst and set based on these measured values.
摘要:
A catalyst for reducing nitrogen oxides, carbon monoxide and hydrocarbons, the noxious components in exhaust gases from internal combustion engines, etc., comprising: a porous carrier consisting essentially of zirconia and at least one oxide selected from the group consisting of cerium oxide, manganese oxide and iron oxide; and a metal as a catalyst ingredient supported thereon selected from the group consisting of platinum, palladium and mixtures thereof.A method for producing the aforesaid catalyst.
摘要:
A catalyst for the steam reforming of hydrocarbons into gases such as methane, hydrogen and carbon monoxide and a method of preparing the same. The catalyst which comprises cerium oxide and rhodium supported on a carrier can maintain high catalytic activity and durability for steam reforming without any carbon deposition on its surface.
摘要:
A catalyst for reducing nitrogen oxides, carbon monoxide and hydrocarbons, the noxious components in exhaust gases from internal combustion engines, etc., comprising: a porous carrier of ceramic selected from the group consisting of alumina and alumina-magnesia spinel; and a catalyst ingredient supported thereon consisting essentially of zirconium oxide, cerium oxide and a metal selected from the group consisting of platinum, palladium and mixtures thereof.
摘要:
A catalyst for reducing nitrogen oxides, carbon monoxide and hydrocarbons, the noxious components in exhaust gases from internal combustion engines, etc., which comprises: a carrier having a substructure of refractory material in the form of a honeycomb structure, etc., and a porous layer of a powder formed on the surface thereof selected from the group consisting of a powder of zirconium oxide and a mixed powder of zirconium oxide powder with at least one powder selected from the group consisting of alumina, alumina-magnesia spinel and cerium oxide; and a catalyst ingredient supported thereon consisting of cerium oxide and a metal selected from the group consisting of platinum, palladium and mixtures thereof.
摘要:
An internal combustion engine in which a three-way catalyst (12) for purification of the exhaust gas is arranged in the exhaust passage, wherein the relationship between the magnitude of the stress causing deterioration of the three-way catalyst (12), for example the catalytic bed temperature, and the rate of deterioration of the performance of the catalyst is found. A durability test is performed by raising the catalytic bed temperature higher than that of the vehicle under market driving. The length of the durability test at this time is determined from the relationship between the catalytic bed temperature and the rate of deterioration of the performance of the catalyst so as to give the same degree of deterioration of the performance of the catalyst as with market driving. The length of the durability test required for giving the same degree of deterioration of the performance of the catalyst is much shorter than the market driving time.
摘要:
A device for evaluating catalyst performance deterioration includes an air-fuel ratio sensor and a temperature sensor. The degree of catalyst performance deterioration per unit time is calculated based on the concentration of oxygen in the exhaust gas and the temperature of the catalyst. The deterioration of the catalyst is evaluated on the basis of the accumulated value of the degree of catalyst performance deterioration per unit time.
摘要:
An exhaust gas purifying catalyst for oxidizing HC and CO and for reducing NOx is provided, which comprises at least one oxide of rare earth element, rhodium, and at least one of platinum and palladium loaded on alumina grains. The major amount of rhodium is dispersed on the oxide of rare earth element. Thus, the rhodium solidification into the alumina grains is prevented. Further, when cerium oxide accompanying lanthanum oxide, neodymium oxide or a mixture thereof is used as the oxide of rare earth element, the sintering of cerium oxide or palladium at a high temperature is suppressed since it forms a complex oxide with lanthanum oxide, neodymium oxide or a mixture thereof. Additionally, when stabilized alumina grains in which a rare earth element and an alkali earth element are present in a solid solution state are used, the deterioration of NOx purifying activity of the catalyst at a high temperature is suppressed. The exhaust gas purifying catalyst of this invention has high durability as well as high activity at a high temperature.
摘要:
This composite oxide powder can secure a large pore volume even after calcination at high temperature and, when a catalyst is formed by loading a noble metal on this composite oxide powder, noble metal grain growth can be suppressed. The composite oxide powder comprises particles of an oxide of a metal M1 and an oxide of a metal M2 which does not dissolve in the oxide of the metal M1, the oxide of the metal M1 and the oxide of the metal M2 being dispersed at the nanometer level. Since different oxides serve as a barrier to each other, sintering is suppressed. Therefore, in the case of composite oxide powder comprising Ce as a metal M1 and Al as a metal M2, grain growth is small even after exposed to high temperature and pores of 3.5-100 nm secure a volume of 0.07 cc/g or more after calcination at 600° C. for 5 hours and a volume of 0.04 cc/g or more after calcination at 800° C. for 5 hours.
摘要:
A catalyst for purifying an exhaust gas includes a support and a noble metal loaded on the support. The support includes a mixture containing a porous oxide and a composite oxide. The composite oxide is expressed by the following formula: (Al2O3)a(CeO2)b(ZrO2)1−b in which the values “a” and “b” are molar ratios and the value “a” falls in a range of from 0.4 to 2.5 and the value “b” falls in a range of from 0.2 to 0.7. The support includes a particle having a particle diameter of 5 &mgr;m or more in an amount of 30% by volume or more. With the thus arranged support, even when the catalyst is subjected to such a severe durability test that it is heated at 1,000° C. for 10 to 20 hours, it exhibits a high purifying activity, and its coating layer is inhibited from cracking or coming off.