The invention relates to a method for treating emergency spill or leak of halogen which is bromine or chlorine, comprising contacting an aqueous solution of quaternary ammonium halide with the halogen.

The present invention is directed to a catalyst system for the reduction of the harmful exhaust-gas constituents hydrocarbons (THC), carbon monoxide (CO), nitrogen oxides (NO.sub.x), and the environmentally detrimental secondary emissions ammonia (NH.sub.3) and nitrous oxide (N.sub.2O) of combustion engines operated using gasoline and to a corresponding method for exhaust-gas purification. The system is characterized by a particular arrangement of catalysts and is used in the case of engines which are operated with predominantly, on average, stoichiometric air/fuel mixtures. Here, a three-way catalyst produced in accordance with the current prior art is preferably installed in a close-coupled position. In the underfloor position, there is situated an SCR catalyst produced in accordance with the current prior art, followed by a further three-way catalyst produced in accordance with the current prior art. The three-way catalyst in the underfloor region furthermore has a lower oxygen-storing capacity than the close-coupled three-way catalyst.

A mixing apparatus for mixing a precursor substance of a reducing agent with exhaust gas, having a housing that provides a mixing chamber and a silencer. The housing inlet side has an inlet connection for exhaust gas and an outlet side having an outlet connection for reducing agent intermixed with the exhaust gas to be discharged. Longitudinal axes of the inlet and outlet connections are offset and parallel relative to one another. An introduction device introduces a precursor substance of the reducing agent and is positioned at the inlet side in a region of the outlet connection longitudinal axis. A length of the housing between the inlet and outlet side at least 1.9 to 7 times a diameter of the inlet connection. A width of the housing is maximally 3 times the diameter of the inlet connection.

Apparatus and methods for coal combustion and for flue gas mercury emissions reduction following the combustion of coal use ammonium halides. Ammonium halides are supplied to a perforated housing within a duct for decomposition and release of NH.sub.3 and HBr or HCl into the flue gas for oxidation of elemental mercury present in the flue gas. The oxidized mercury is then separated from the flue gas using a particulate collection system and/or a wet flue gas desulfurization system for flue gas mercury emissions reduction.

Various embodiments disclosed relate to sorbents for the oxidation and removal of mercury. The present invention includes removing mercury from a mercury-containing gas using a halide-promoted and optionally ammonium-protected sorbent that can include carbon sorbent, non-carbon sorbent, or a combination thereof.

A waste gas is contacted with a mercury removal agent to remove mercury and a flue gas conditioning agent to alter a resistivity and/or cohesivity of particulates. The flue gas conditioning agent can be substantially free of SO.sub.3 and/or comprise more than about 25 wt. % SO.sub.3, and/or the mercury removal agent can be substantially unaffected by the flue gas conditioning agent. An amount of mercury removed from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent. An amount of the acid gas removed, by an acid gas removal agent, from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent.

Disclosed herein are methods for treating an exhaust stream comprising NOx, the methods comprising receiving an exhaust stream and combining it with at least one nitrogen-containing reagent to form a combined stream, heating the combined stream to a reaction temperature ranging from about 870 C. to about 1100 C. to react at least a portion of the nitrogen-containing component, cooling the reacted stream in a first cooling step to a first temperature, and optionally further cooling the reacted stream in a second cooling step to a second temperature, wherein the first cooling step comprises heat exchange between at least a portion of the exhaust stream and at least a portion of the reacted stream. Exhaust treatment systems are also disclosed herein.

Denitrifying bypass exhaust gases in a cement clinker producing plant. The plant comprises a rotary kiln connected to a calciner for the deacidification of raw material or to a rotary kiln riser shaft via a rotary kiln inlet chamber, and the bypass exhaust gas being drawn off in the region of the rotary kiln inlet chamber. The method comprises: cooling the bypass gas to between 260 C and 400 C in a cooling device, injecting an ammonia-, urea-, and/or ammonium-containing substance into the cooled bypass gas, introducing the cooled and mixed bypass gas into a ceramic filter system to filter out any halide and sulfate of the alkali metals and alkaline-earth metals precipitated during cooling the gas, and any nitrogen not reacted by the injected substances is chemically selectively reduced over a catalytic converter which is located in or directly downstream of the ceramic filter system.

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

A waste gas is contacted with a mercury removal agent to remove mercury and a flue gas conditioning agent to alter a resistivity and/or cohesivity of particulates. The flue gas conditioning agent can be substantially free of SO.sub.3and/or comprise more than about 25 wt. % SO.sub.3, and/or the mercury removal agent can be substantially unaffected by the flue gas conditioning agent. An amount of mercury removed from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent. An amount of the acid gas removed, by an acid gas removal agent, from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent.