Siemens Aktiengesellschaft

G&uuml;nther Pajonk

Frank Witzel

Manfred Weigl

Lothar Hofmann

Stefan Fischer

Gerhard Wissler

Ronald Neufert

Andreas Girschik

Catalyst body for breaking down halogenated hydrocarbons, in particular dioxins and/or furans, having an active material which comprises titanium dioxide, carbon and at least one active component which is selected from the group consisting of oxides and mixed oxides of the transition metals, of the lanthanides, of the actinides, of the alkali metals and alkaline-earth metals, of aluminum, of tin and of silicon. In an off-gas flowing through the catalyst body, the levels of hydrocarbons contained therein are effectively reduced in part by adsorption and in part by oxidation, in particular at temperatures below 250&deg; C.

Process for reducing the levels of halogenated hydrocarbons

A process for producing a catalyst body includes providing titanium dioxide, tungsten trioxide, vanadium pentoxide, aluminum oxide, and/or silicon oxide for the catalyst body. A kneadable and/or shapable compound is processed to form a shaped body by extrusion or by coating of a support body. The shaped body is dried and is calcined to form an active compound. The calcined shaped body is artificially aged by a final heat treatment at a temperature higher than the calcination temperature to produce a catalyst body having a high resistance to deactivation at high temperatures. The starting materials include from 65 to 95% by weight of titanium dioxide, 2 to 30% by weight of tungsten trioxide, 0 to 2% by weight of vanadium pentoxide, preferably, less than 1.5%, 0.1 to 10% by weight of aluminum oxide, and 0.1 to 10% by weight of silicon dioxide. The final heat treatment is done is at 660 to 700&deg; C., drying is at 20 to 100&deg; C. prior to calcination, and calcination is at 400&deg; C. to less than 700&deg; C.

Process for producing a catalyst body

A gas stream that contains nitrogen oxides is passed, in the presence of a reducing agent, over a catalyst body with an active material that contains a zeolite and titanium dioxide. The zeolite is a hydrogen-ion-exchanged, acid zeolite. Even at temperatures above 450&deg; C., the nitrogen oxides contained are still effectively converted into nitrogen and water.

Catalyst body and process for breaking down nitrogen oxides

To produce a catalytically active material, titanium dioxide, together with an oxide or with a dissolved compound of tungsten and/or vanadium, is processed into a shapeable material. the shapeable material is dried to form a shaped body, and the shaped body is calcined. After the calcining, the shaped body is additionally impregnated with a dissolved compound of titanium and vanadium and is dried again. A catalytically active material of this type has a high catalytic activity with regard to breaking down dioxins and/or furans even in a temperature range of below 250&deg; C. The catalytically active material is particularly suitable for producing dioxin and/or furan catalytic converters.

PROCESS FOR PRODUCING A CATALYTICALLY ACTIVE MATERIAL, CATALYTIC CONVERTER HAVING A CATALYTICALLY ACTIVE MATERIAL PRODUCED IN THIS MANNER, AND USE OF THE CATALYTIC CONVERTER TO BREAK DOWN DIOXINS AND/OR FURANS

To ensure the maximum possible conversion of nitrogen oxides in a DeNO catalytic converter in an off-gas cleaning installation for reducing nitrogen oxides and, at the same time, to prevent the reducing agent which is used for the reduction from escaping into the environment, there is provision for the density of a reducing agent solution to be used to determine the volume of the reducing agent solution which is to be metered. The density is regulated in two ways, in that the temperature of the reducing agent solution is measured using a temperature sensor and set by a temperature-control device.

Method and device for the catalytic reduction of nitrogen oxides contained in the off-gas from a combustion system

When determining the amount of a reducing agent solution to be introduced into the exhaust gas of a combustion system, in particular of a diesel engine, for catalytically reducing the nitrogen oxides by the SCR process, the concentration of the reducing agent in the reducing agent solution as well as the parameters characterizing the operating state of the combustion system, the exhaust gas and/or the catalyst are taken into consideration. As a result, the safety margin with respect to a theoretically optimum amount to be introduced that is required to avoid a leakage of reducing agent can be reduced, whereby the conversion rate of the nitrogen oxides is improved.

Method and device for reducing the nitrogen oxides in the exhaust gas of a combustion system

A catalyst body, which contains a number of passages through which a medium can flow in a preferred direction, is to be able to operate reliably with little cleaning outlay. It is also intended for cracking during the process of manufacturing the catalyst body to be particularly rare. For this purpose, each passage, disposed at right angles to the preferred direction, is approximately rectangular in cross section, as defined by a longitudinal side and a shorter transverse side. The number of passages per unit surface area lies in the range from 0.5 to 2.5 cm,, and the longitudinal sides of a first group of the passages are disposed approximately at right angles to the longitudinal sides of a second group of the passages. The passages are in this case combined to form subgroups, the passages of each subgroup, in terms of their cross sections, forming an approximately square configuration, and each subgroup containing in each case passages from the same group.

Catalyst body

A tank for a vehicle having a selective catalytic reduction exhaust gas purification system operating with a reducing agent includes a fuel space for the vehicle fuel and a reducing agent space for the reducing agent. The fuel space and the reducing agent space are combined into a single structural that can be fastened as a whole to the vehicle by brackets on the structural unit. This utilizes the limited space available in any vehicle as efficiently as possible and eliminates the need to provide mounting arrangements for separate fuel and reducing agent tanks.

Dual compartment fuel storage tank

Excessive NO,emission in a diesel internal combustion engine with SCR exhaust gas treatment is detected by a control unit. The excessive NO,emission value is determined from the catalytic-converter efficiency calculated for the metering of the reducing agent. In response, measures are taken, such as delayed start of the fuel injection, deactivation of a coasting cutoff, reducing an exhaust gas recirculation rate and/or increasing the idling speed. As a result, the NO,content in the untreated exhaust gas drops, the catalytic-converter temperature increases more quickly after a cold start, and the NO,emission is reduced.

Growing community of inventors

Zapfendorf, Germany

Günther Pajonk

Growing community of inventors

Zapfendorf, Germany

G&uuml;nther Pajonk

Günther Pajonk