Abstract: A process and apparatus for reducing the nitrogen oxide content in oxygen-containing emissions is provided, particularly for internal-combustion engines, particularly of diesel engines and directly injecting Otto engines for motor vehicles. The nitrogen oxides contained in the exhaust gas are reduced by a suitable reducing agent, such as hydrogen or hydrocarbons, on a DENOX catalyst. For achieving an improved conversion rate for the nitrogen oxides, a combination of hydrogen and hydrocarbons are used as reducing agents. In different operating ranges of the internal-combustion engine only hydrogen, only hydrocarbons, or hydrogen and hydrocarbons are added. Preferably, for this purpose, the quantity of supplied hydrogen or hydrocarbons is reduced or increased with an increasing engine load and/or catalyst temperature and/or rotational engine speed.

Abstract: A motor vehicle exhaust emission control system has two adsorber parts connected in parallel for alternate adsorption and desorption of nitrogen oxides contained in the exhaust from an internal combustion engine and components for conducting further downstream the exhaust that emerges in the adsorber part that is operating at any given time in the adsorption mode and for returning the exhaust that emerges from the other adsorber part that is then operating in the desorption mode, to an intake line of the engine. An oxidizing converter is located upstream of the adsorber part and near the engine for oxidation of the NO contained in the exhaust to form NO.sub.2, so as to permit an increase in the NO.sub.X adsorption rate for the nitrogen adsorber parts.

Abstract: A material and a process for adsorbing and desorbing nitrogen oxides in exhaust gas systems of engines running on a lean mixture, which does not require a prior oxidation step, wherein a mixed oxide which has an oxygen-rich orthorhombic structure is used which changes to an oxygen-poor tetragonal structure as a function of temperature.

Abstract: A method and an apparatus are provided for operating a diesel engine with an exhaust feedback device located between the exhaust line and the intake air line, with an adjusting element that can be operated by an adjusting drive actuated by an auxiliary force to operate the exhaust feedback device as a function of signals from an electronic control device. An engine regulator permits rich/lean regulation of the diesel engine as a function of its operating parameters. A storage catalyst is located in the exhaust line, in which catalyst oxides of nitrogen (NO.sub.x) can be adsorbed, desorbed, and reduced. A sensor is located downstream from the storage catalyst for detecting the NO.sub.x concentration in the exhaust stream in such fashion that when an NO.sub.x storage threshold value is reached that varies in terms of its characteristics as a function of the rpm and the load, a switch is made from operation with a lambda value of larger than 1 to operation with a lambda value of less than 1.

Abstract: A process and apparatus for the selective catalyzed NO.sub.x reduction in oxygen-containing exhaust gases of internal-combustion engines. For improving the reduction of nitric oxides, hydrocarbons and air are supplied to the exhaust gas purifier and, for producing reactive short-chained unsaturated hydrocarbons, a defined quantity of fuel from the stored fuel intended for the fuel supply of the internal-combustion engine is catalytically cracked and is oxidized by the simultaneous supply of air. The resulting species are guided into the exhaust gas flow of the exhaust gases which are to be purified.

Abstract: The invention relates to a gasoline engine having a catalyst for reducing the emission pollutants, with an oxygen absorption device located in the exhaust line upstream of the catalyst. According to the invention, the gasoline engine is operated in a first operating range with a lean air/fuel ratio (.lambda.), and oxygen is removed from the exhaust by the absorption device. In a second operating range, the gasoline engine is operated at .lambda.=1, and the absorption device is bypassed or deactivated. In the case of a gasoline engine with a Denox catalyst the gasoline engine is operated constantly with a lean air/fuel ratio, with the active surface of the Denox catalyst being "depoisoned" temporarily by activating the oxygen absorption device.

Abstract: A diesel fuel containing an additive which improves the combustion of soot, for reducing the pollutant emission in the combustion exhaust gases from diesel engines by discontinuous burning-off of soot which has been precipitated in the exhaust gas filter, is described. For this purpose, a lithium, sodium or potassium salt of an aliphatic or aromatic alcohol, of a phenol, of an aliphatic acid or of a naphthoic acid, phenylacetic acid or cinnamic acid is added, singly or as a mixture, to the diesel fuel before the combustion of the latter in the internal combustion engine. As a result of the addition of the alkali metal salts, the ignition temperature of the soot precipitated in the particle filter is reduced, and the soot is oxidized at a temperature which is considerably lower than the normal ignition temperature. The regeneration range for the particle filter is therefore reached much more frequently in real running practice.

Abstract: The invention relates to a diesel internal combustion engine with an exhaust treatment device for the reduction of nitrogen oxides and with a fuel injection system comprising a high-pressure pump and at least one solenoid valve-controlled injection nozzle. The injection nozzle is actuated by an electronic control unit and is intended both for the primary injection, provided for the combustion, and for the additional injection, influencing the effectiveness of the exhaust treatment device. The fuel injection nozzle provided for the primary injection also provides for the secondary injection. The secondary injection takes place as a supplementary injection at the earliest in the region of the end phase of the combustion after the ignition top dead center.

Abstract: In an apparatus for reducing the nitrogen oxide emission of an internal combustion engine wherein the nitrogen oxides are removed from the engine exhaust gas in an adsorber from which they are subsequently purged by hot gases, the hot gases with the nitrogen oxides purged from the adsorber are returned to the air intake of the internal combustion engine for reaction in the combustion process in the internal combustion engine in which the nitrogen oxide is converted to nitrogen and oxygen.

Abstract: A method and an apparatus reduces particles in exhaust gases of an internal combustion engine by passing the exhaust gases through a microwave energy field in a resonator for applying energy and burning the particles. In order to improve the application of energy, the particles are agglomerated beforehand in a high-voltage field of an electrostatic filter.