Treatment of radioactive waste comprising organic compounds and sulfur-containing compounds and/or halogen-containing compounds. An apparatus comprises a reaction vessel comprising a filter for carrying out thermal treatment of the waste and a thermal oxidizer. Utilizing co-reactants to reduce gas phase sulfur and halogen from treatment of wastes.

An absorbent for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, wherein the absorbent contains an aqueous solution, comprising: a) an amine or a mixture of amines of the general formula (I) wherein R.sup.1 is C.sub.1-C.sub.5-alkyl; R.sup.2 is C.sub.1-C.sub.5-alkyl; R.sup.3 is selected from hydrogen and C.sub.1-C.sub.5-alkyl; x is an integer from 2 to 10; and b) an ether or a mixture of ethers of the general formula (II): R.sup.4[OCH.sub.2CH.sub.2].sub.yOH; wherein R.sup.4 is C.sub.1-C.sub.5-alkyl; and y is an integer from 2 to 10; wherein R.sup.1 and R.sup.4 are identical; wherein the mass ratio of b) to a) is from 0.08 to 0.5. The absorbent is suitable for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide. The absorbent has a reduced tendency for phase separation at temperatures falling within the usual range of regeneration temperatures for the aqueous amine mixtures and is easily obtainable.

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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.

Embodiments of the disclosure provide a method and a Claus tail gas treatment system for sulfur recovery. A tail gas stream is fed to a hydrogenation reactor to produce a hydrogenated gas stream by converting sulfur-containing compounds to hydrogen sulfide. The hydrogenated gas stream is fed to a quench tower to produce a quenched gas stream by condensing and recovering liquid water via a water condensate stream. The quenched gas stream is fed to a first stage adsorption unit to produce a first outlet gas stream by separating water via a first byproduct stream from hydrogen sulfide, carbon dioxide, and nitrogen. The first outlet stream is fed to a second stage adsorption unit to produce a second outlet gas stream by separating carbon dioxide and nitrogen via a second byproduct stream. The second outlet stream includes hydrogen sulfide. The second outlet stream can be fed to a Claus unit.

Disclosed embodiments provide a system and method for producing hydrocarbons from biomass. Certain embodiments of the method are particularly useful for producing substitute natural gas from forestry residues. Certain disclosed embodiments of the method convert a biomass feedstock into a product hydrocarbon by hydropyrolysis. Catalytic conversion of the resulting pyrolysis gas to the product hydrocarbon and carbon dioxide occurs in the presence of hydrogen and steam over a CO.sub.2 sorbent with simultaneous generation of the required hydrogen by reaction with steam. A gas separator purifies product methane, while forcing recycle of internally generated hydrogen to obtain high conversion of the biomass feedstock to the desired hydrocarbon product. While methane is a preferred hydrocarbon product, liquid hydrocarbon products also can be delivered.

Sorbent compositions containing calcium and iodine are added to coal to mitigate the release of mercury and/or other harmful elements into the environment during combustion of coal containing natural levels of mercury.

A sulfur trap provides separation of elemental molten sulfur from a process stream comprising a mixture of sulfur and associated tail-gases. The sulfur trap comprises a vertically-oriented cylindrical wall having a chamber for receiving the process stream, a float positioned in the chamber, the float attached to a float end of a lever, a nozzle insert attached to the distal end of the lever, and a lever fulcrum positioned intermediate the lever float end and the lever nozzle insert end. The float, lever, nozzle insert and outlet are constructed to allow the float position to control nozzle insert engagement of the outlet, particularly to close the outlet when the float is elevated by molten sulfur and to disengage from the outlet to allow discharge flow of liquid sulfur at a determined level of sulfur within the chamber. Embodiments of a method of separating liquid sulfur from gases are also provided.

Sorbent compositions containing halogen and either nitrates or nitrites are added to coal to mitigate the release of mercury and/or other harmful elements into the environment during combustion of coal containing natural levels of mercury.

Materials which react with (scavenge) sulfur compounds, such as hydrogen sulfide and mercaptans, are useful for limiting sulfur-induced corrosion. Surface-modified particles incorporating a hexahydrotriazine moiety are disclosed and used as sulfur scavengers. These surface-modified particles are used a filter media in fixed filter systems and as additives to fluids including sulfur compounds. The hexahydrotriazine moiety can react with sulfur compounds in such a manner as to bind sulfur atoms to the surface-modified particles, thus allowing removal of the sulfur atoms from fluids such as crude oil, natural gas, hydrocarbon combustion exhaust gases, sulfur polluted air and water. The surface-modified particles may, in general, be sized to allow separation of the particles from the process fluid by sedimentation, size-exclusion filtration or the like.

A fuel cell system includes a hot box, a stack of fuel cells disposed in the hot box, and a desulfurization subsystem. The desulfurization subsystem may include a sulfur adsorption reactor containing a metal oxide, such as ZnO, configured to adsorb sulfur species from fuel, a first fuel conduit configured to provide fuel to the reactor, and a second fuel conduit configured to receive fuel from the reactor. The desulfurization subsystem may be configured to heat the reactor to an operating temperature ranging from about 200 C. to about 450 C., using heat generated in the hot box.