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).

Processes and compositions for scavenging hydrogen sulfide from hydrocarbon streams are disclosed that reduce, if not substantially eliminate, the formation of crystalline or amorphous solids even under cold conditions. The compositions used in the processes comprise a hexahydrotriazine component and an amphiphilic component that form a hydrophobic micelle when the hexahydrotriazine component becomes spent.

For the purification of waste gas containing carbon compounds and nitrogen oxides by means of a regenerative post-combustion system, at least two regenerators (A, B, C) filled with heat accumulator bodies (7a, 7b, 7c) and connected by a combustion chamber (10) are provided, wherein the waste gas is alternately heated in a regenerator (A, B, C), the carbon compounds are oxidised in the combustion chamber (10), and, with the addition of a nitrogen-hydrogen compound, the nitrogen oxides are reduced in the combustion chamber (10) thermally and thus not catalytically. Remaining nitrogen oxides are removed by means of a catalytically active heat accumulator layer (6a, 6b, 6c) and the addition of a further nitrogen-hydrogen compound in the regenerator (A, B, C) from which the clean gas exits.

A filtration device for an air purification appliance includes a first filtering cartridge structure containing a classic absorbent or adsorbent material selected from activated carbon or zeolite and a second, different filtering cartridge structure holding a filtering medium consisting of a specific adsorbent material which is porous and functionalized with at least one probe molecule in such a way as to trap aldehyde-type chemical contaminants.

Internal Combustion Engines, both Compression-Ignition (CI), mainly for Diesel oil, and Spark Ignition, for Gasoline, Compressed Natural Gas (CNG) or LPG emit pollutants during operation but particularly during cold startup in addition to nitrogen, carbon dioxide and water. The POLLUTANTS are: Carbon Monoxide (CO) Unburned Hydrocarbons (HC) and Nitrogen-Oxides (NOx) All cars today must be equipped with Catalytic Converters for oxidizing the CO to C02 and the HC to C02 and water and for the reduction of the NOx to N2 and water. These catalysts are inactive at temperatures below ca. 300 deg.c. and so when starting an engine from cold the emission of pollutants is high and not mitigated by the catalysts. Another problem is that a Reductant is required for the reduction of the NOx to N2 and water and the reductants in the exhaust gases namely CO and HC or Ammonia or Urea added to the flue gases are not efficient enough to fulfill the more stringent requirements for very low emission of NOx, There were many suggestions, in the literature and patents that propose the use of electrical heating of the catalysts monoliths, however the high burden on the batteries and also the long time needed for the heating made this approach virtually impractical. Another approach, for the DENOx and sometimes also for the cold startup was to manufacture hydrogen from water by electrolysis and first, store hydrogen and oxygen for injection into cold catalysts and ignite it prior to injection of the main fuel to the engine and secondly, during the run to produce hydrogen to be used as the reductant of NOx This approach also proved to be too difficult and costly and altogether impractical. In the present invention here an auxiliary small fuel system, preferably alcohol like Methanol, is installed. At cold startup the injection of the main fuel, such as Diesel Oil for CI engines or Gasoline for SI engines, is delayed for a few seconds and the compressed air from the engine flows into the after treatment main passage and mixes with injected Methanol and the mixture flows into the first catalyst section where at the inlet a metal net connected to an electrical source, such as a car battery, is heated igniting the mixture of air-methanol until the catalyst section is heated and then, in sequence, all catalyst sections, and in the case of a Diesel Engine also the DPF (DIESEL PARTICULATES FILTER), are heated up to the effective operating temperature. At that point all Methanol supply is cut off and a Methanol-Water mix is injected to a catalytic hydrogen production section (HPC) which is installed in parallel to the main exhaust passage and the Hydrogen rich stream is injected as the reda

The present invention relates to a carbon dioxide conversion process and, more particularly, to a continuous carbon dioxide conversion process and a system therefor.

A process to remove H.sub.2S from a stream comprising the steps of adding a glyoxal, a silica nanoparticle composition, and optionally a triazine to the stream. The stream is selected from the group consisting of Oil streams, Gas streams, CO.sub.2 point source purification streams and Geothermal Energy System streams.

Provided is a composition for removing a sulfur-containing compound present in liquid or vapor, the sulfur-containing compound being hydrogen sulfide, an SH group-containing compound or a mixture thereof, the composition containing an ,-unsaturated aldehyde represented by the following general formula (1) as an active ingredient;

##STR00001##

wherein R.sup.1 and R.sup.2 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or an aryl group having 6 to 12 carbon atoms, or are connected to each other to represent an alkylene group having 2 to 6 carbon atoms; and R.sup.3 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, or is connected to R.sup.1 to represent an alkylene group having 2 to 6 carbon atoms.

A scrubber system configured to react gas phase nitrogen dioxide and carbon monoxide emissions from process applications in scrubber tower equipment with the use of reducing agent chemistry combined with copper silver ionization.

Disclosed herein is a system for purifying air; for the capture of solid residues (soot), and the transformation of CO.sub.x and NO.sub.x (and even methane) present in contaminated air generated by industrial combustion. The purifying air system comprises an air entrance (c); a first module (A), made up of mechanical filters; a second module (B), downwards from the first module (A), and it corresponds to a series of small reactors with molecular converters (nucleophile chemical agents) to capture and transform carbon oxides (CO.sub.x) and nitrogen oxides (NO.sub.x); and an exit for decontaminated air (D).