Described is a process for the treatment of a gas stream containing nitrogen oxides. The process comprises the steps of: (1) providing a gas stream containing one or more nitrogen oxides; (2) contacting the gas stream provided in step (1) with a transition metal containing zeolitic material having a BEA-type framework structure for reacting one or more of the nitrogen oxides; wherein the zeolitic material is obtainable from an organotemplate-free synthetic process. Also described is an apparatus for the treatment of a gas stream comprising containing nitrogen oxides.

A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler. Some embodiments of a biogas cleaning method can also include precooling the biogas waste stream, adsorbing siloxanes from the biogas waste stream and adsorbing hydrogen chloride from the biogas stream.

A system and method for the reduction of NOx and CO contaminants using an ion-exchange resin media having lower-valency ions of the transitional metal elements, such as ferrous ions, cuprous ions and/or manganese ions, such that gases containing NOx and/or CO contaminants may be passed over the media so that the contaminants are absorbed by the lower-valency ions of the transitional metal elements, the media configured so that it can be regenerated to remove the NOx and/or CO contaminants. Regeneration includes exposing the media to a heated stream of hydrogen gas or exposing the media to hydrogen ions in an electrochemical cell.

The present invention relates to a method and a system for catalytic oxidation of a lean H.sub.2S stream. More specifically, the invention concerns a novel way of removing sulfur dioxide (SO.sub.2) formed by catalytic oxidation of hydrogen sulfide (H.sub.2S) with the purpose of removing H.sub.2S from a gas. This catalytic oxidation of H.sub.2S yields sulfur dioxide (SO.sub.2) through the use of known catalysts, so-called SMC catalysts.

A system and method for the reduction of NOx and CO contaminants using an ion-exchange resin media having lower-valency ions of the transitional metal elements, such as ferrous ions, cuprous ions and/or manganese ions, such that gases containing NOx and/or CO contaminants may be passed over the media so that the contaminants are absorbed by the lower-valency ions of the transitional metal elements, the media configured so that it can be regenerated to remove the NOx and/or CO contaminants. Regeneration includes exposing the media to a heated stream of hydrogen gas or exposing the media to hydrogen ions in an electrochemical cell.

The invention provides a device and system for decomposing and oxidizing of gaseous pollutants. A novel reaction portion reduces particle formation in fluids during treatment, thereby improving the defect of particle accumulation in a reaction portion. Also, the system includes the device, wherein a modular design enables the system to have the advantage of easy repair and maintenance.

A method for the purification of a raw gas stream by selective catalytic oxidation, in which organic and inorganic sulfur compounds, halogenated and non-halogenated volatile organic compounds are selectively oxidized without substantially oxidizing the lower hydrocarbons and the sulfur containing compounds present in the gas to sulfur trioxide and excess of oxygen is removed by oxidation of lower alcohols, ethers or hydrogen added to the raw gas stream upstream the catalytic oxidation.

A nitrous oxide (N.sub.2O) removal catalyst composition for treating an exhaust stream of an internal combustion engine is provided, containing a platinum group metal (PGM) component on a metal oxide-based support, wherein the N.sub.2O removal catalyst composition is in a substantially reduced form, such that it has an oxygen deficiency of about 0.05 mmol oxygen atoms/g or greater, and wherein the N.sub.2O removal catalyst composition provides effective removal of at least a portion of N.sub.2O from the exhaust stream under lean conditions at a temperature of about 350 C. or lower. N.sub.2O removal catalytic articles, systems, and methods are also provided for removing at least a portion of N.sub.2O from an exhaust stream under lean, low temperature conditions.

Oxygen is removed from a gas feed such as a landfill gas, a digester gas or an industrial CO.sub.2 off-gas by heating the feed gas, optionally removing siloxanes and silanols from the heated feed gas, optionally removing part of the sulfur-containing compounds in the heated feed gas, injecting one or more reactants for oxygen conversion into the heated feed gas, carrying out a selective catalytic conversion of any or all of the volatile organic compounds (VOCs) present in the gas, including sulfur-containing compounds, chlorine-containing compounds and any of the reactants injected, in at least one suitable reactor, and cleaning the resulting oxygen-depleted gas. The reactants to be injected comprise one or more of H.sub.2, CO, ammonia, urea, methanol, ethanol and dimethyl ether (DME).

The invention provides a device and system for decomposing and oxidizing of gaseous pollutants. A novel reaction portion reduces particle formation in fluids during treatment, thereby improving the defect of particle accumulation in a reaction portion. Also, the system includes the device, wherein a modular design enables the system to have the advantage of easy repair and maintenance.