Abstract: The invention relates to a process for the selective catalytic reduction of the nitrogen oxides contained in a lean exhaust gas from internal combustion engines by reducing the nitrogen oxides by means of ammonia on a catalyst. The process is characterized in that, in addition to the lean exhaust gas, a rich gas stream is produced that is treated in an electrical gas discharge plasma in order to form the ammonia required for the reduction.

Abstract: A method for removing nitrogen oxides from a lean flue gas.

Abstract: A process for checking the operability of an exhaust gas purification catalyst for diesel engines, which has a light-off temperature and a degree of conversion rCO for carbon monoxide (CO), by direct measurement of the carbon monoxide concentration in combination with a temperature measurement.

Abstract: The invention relates to a process for the selective catalytic reduction of the nitrogen oxides contained in a lean exhaust gas from internal combustion engines by reducing the nitrogen oxides by means of ammonia on a catalyst. The process is characterized in that, in addition to the lean exhaust gas, a rich gas stream is produced that is treated in an electrical gas discharge plasma in order to form the ammonia required for the reduction.

Abstract: A process for reducing the nitrogen oxides content of the exhaust gas from an internal combustion engine includes treating the exhaust gas in an electric gas discharge such that at least one of nitrogen dioxide or nitric acid are formed from nitrogen oxides in the exhaust gas; storing the nitrogen dioxides and/or the nitric acid in the form of nitrates on a nitrogen oxides storage material during phases when the engine operates with a greater than a stoichiometric air/fuel ratio (i.e., the storage phase); decomposing the nitrates to give nitrogen oxides during brief phases when the engine operates with a less than the stoichiometric air/fuel ratio (i.e., the desorption phase); and reducing the nitrogen oxides which are released from the storage material to nitrogen. The nitrogen oxides storage material may be located in an electric gas discharge zone, and the exhaust gas may be passed through the discharge and then over the storage material.

Abstract: An auxiliary heating system for a motor vehicle with an internal combustion engine. The auxiliary heating includes an emission control catalyst and a heat exchanger, integrated in the converter housing in front of and/or behind the catalyst, which provides the reaction heat released by the catalyst and the remaining heat of the exhaust gas to the heating of the passenger compartment. The heat generation may be increased by the injection of a fuel/air mixture before the catalyst and by using the catalyst as a catalytic burner and can be adapted to the heat requirements. The auxiliary heating of the invention prevents possible thermal damage of the catalyst during operation as a catalytic burner without many regulating elements by cooling the catalyst radiation. For this purpose, the heat exchanger is provided with an exchange surface which can freely exchange radiation with the radiant surface of the catalytic element.

Abstract: A water heater has a gas inlet (8) for a mixture of gas and air and an in for a fluid (2) to be heated. The gas-air mixture passes through a combustion chamber (11,18) which is at least partly surrounded by at least one fluid chamber (4,7) filled with the fluid (2). The exhaust gas leaving the combustion chamber(s) (11,18) passes through an exhaust gas heat exchanger together with the fluid (2). Here there are two combustion stages, the first (16) being a catalytic gap burner (11) and the second being a monolithic burner (18,19). Owing to the two-stage arrangement, about 80% of the combustion gas is burned in the combustion stage (16) while the remainder is consumed even at the low partial pressures in the second combustion stage (20) virtually without any residue, and especially without emission of NO.sub.x.