Sulfide scavengers useful to reduce sulfide concentration in fluid streams and methods of using these scavengers. The scavengers comprise oil soluble reaction products of formaldehyde/N-substituted hydroxylamines and can be used to reduce, for example, H.sub.2S content in viscous hydrocarbon oil streams.

The present disclosure provides a method for the separation of a gas constituent from a gaseous mixture. The disclosure also provides polyethylene glycol disubstituted siloxane based solvents for use in the method. These solvents are of use for pre-combustion CO.sub.2 capture and are capable of replacing glycol-based solvents while offering operation at a higher temperature region. These solvents are also of use for generation of hydrogen from reformed natural gas or syngas, adjusting CO/H.sub.2 ratio for Coal & Biomass to Liquids, removal of CO.sub.2 from syngas for coal & biomass to NH.sub.3/Fertilizer, natural gas sweetening, and upgrading of landfill and biogas.

Systems comprising a composition where an imidazole is tethered to an amine and a solvent are described herein. Methods of their preparation and use are also described herein. The methods of using the systems include the reduction of volatile compounds from gas streams and liquid stream.

A process for removing hydrogen sulfide and carbon dioxide from a fluid stream comprises a) an absorption step in which the fluid stream is contacted with an absorbent comprising an aqueous solution (i) of an amine of the general formula (I)

##STR00001##

in which R.sub.1, R.sub.2 and R.sub.3 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.4 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.5 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; X is OH or NH(CR.sub.1R.sub.2R.sub.3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and optionally (ii) at least one tertiary amine, where the molar ratio of (i) to (ii) is greater than 0.05; wherein at least 90% of the hydrogen sulfide is removed from the fluid stream and selectivity for hydrogen sulfide over carbon dioxide is not greater than 8, wherein a CO.sub.2- and H.sub.2S-laden absorbent is obtained; b) a regeneration step in which at least a substream of the CO.sub.2- and H.sub.2S-laden absorbent is regenerated and a regenerated absorbent is obtained; and c) a recycling step in which at least a substream of the regenerated absorbent is recycled into the absorption step a). The process allows a high level of hydrogen sulfide removal with a simultaneously high coabsorption of carbon dioxide.

An absorbent for removing carbon dioxide from a fluid stream, comprising an aqueous solution a) of an amine of the general formula (I) ##STR00001##
in which R.sub.1, R.sub.2 and R.sub.3 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.4 is independently selected from hydrogen, C.sub.1-4alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.5 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; X is OH or NH(CR.sub.1R.sub.2R.sub.3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and b) at least one activator selected from b1) a sterically unhindered primary amine and/or a sterically unhindered secondary amine; and a carboanhydrase. The absorbent allows rapid absorption of carbon dioxide from fluid streams.

Disclosed herein are scavenging compounds and compositions useful in applications relating to the production, transportation, storage, and separation of crude oil and natural gas. Also disclosed herein are methods of using the compounds and compositions as scavengers, particularly in applications relating to the production, transportation, storage, and separation of crude oil and natural gas.

A composition and a device for purification of nitrogen-oxide-containing gas is provided. It can purify harmful nitrogen-oxide-containing gases, such as nitric oxide or nitrogen dioxide. The composition includes an alkaline substance and at least one organic acid, the organic acids having an enediol group, enediamine group, or amine group of cyclopentane compounds, cyclohexane compounds, cycloheptane compounds, or phenanthrene compounds.

This invention provides compositions and methods that inhibit formation of alkenyl sulfide polymers and allow the hydrogen sulfide to be removed when scavenging hydrogen sulfide by reaction with aldehydes.

This invention provides compositions and methods that inhibit formation of alkenyl sulfide polymers and allow the hydrogen sulfide to be removed when scavenging hydrogen sulfide by reaction with aldehydes.

A process for removing hydrogen sulfide and carbon dioxide from a fluid stream comprises a) an absorption step in which the fluid stream is contacted with an absorbent comprising an aqueous solution (i) of an amine of the general formula (I) ##STR00001##
in which R.sub.1, R.sub.2 and R.sub.3 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.4 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.5 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; X is OH or NH(CR.sub.1R.sub.2R.sub.3); m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is 0 or 1; and optionally (ii) at least one tertiary amine, where the molar ratio of (i) to (ii) is greater than 0.05; wherein at least 90% of the hydrogen sulfide is removed from the fluid stream and selectivity for hydrogen sulfide over carbon dioxide is not greater than 8, wherein a CO.sub.2- and H.sub.2S-laden absorbent is obtained; b) a regeneration step in which at least a substream of the CO.sub.2- and H.sub.2S-laden absorbent is regenerated and a regenerated absorbent is obtained; and c) a recycling step in which at least a substream of the regenerated absorbent is recycled into the absorption step a). The process allows a high level of hydrogen sulfide removal with a simultaneously high coabsorption of carbon dioxide.