Plants, processes, and methods for reducing the H.sub.2S and CO.sub.2 contents of shale gasses from fields that produce shale gasses having varying H.sub.2S and CO.sub.2 contents are provided. Acid gas enters an absorber and is scrubbed using a lean physical solvent, producing a treated gas and a rich physical solvent. The H.sub.2S content of the treated gas is further reduced in an amine absorber, producing a pipeline gas and a semi-lean amine. The pipeline gas contains lower levels of H.sub.2S and CO.sub.2 than gas produced using a polishing bed. A physical solvent regeneration unit regenerates the lean physical solvent from the rich physical solvent for feeding into the absorption unit. An amine regeneration unit regenerates the lean amine from the semi-lean amine for feeding into the amine absorber. Contemplated plants may further comprise a Claus Unit or a Redox unit for oxidizing H.sub.2S to elemental sulfur.

A process for component separation in a polymer production system, comprising separating a polymerization product stream into a gas stream and a polymer stream, wherein the gas stream comprises ethane and unreacted ethylene, distilling the gas stream into a light hydrocarbon stream, wherein the light hydrocarbon stream comprises ethane and unreacted ethylene, contacting the light hydrocarbon stream with an absorption solvent system, wherein at least a portion of the unreacted ethylene from the light hydrocarbon stream is absorbed by the absorption solvent system, and recovering a waste gas stream from the absorption solvent system, wherein the waste gas stream comprises ethane, hydrogen, or combinations thereof.

A process for reducing the amount of CO.sub.2 released into the atmosphere with the exhaust gas stream produced by the combustion of a hydrocarbon fuel in an internal combustion engine (ICE) used to power a vehicle by capturing at least a portion of the CO.sub.2 in a liquid sorbent on board the vehicle, recovering the CO.sub.2 from the sorbent and compressing the CO.sub.2 for temporary storage on board the vehicle, where the process is operated as a semi-closed system in which the liquid sorbent that captures the CO.sub.2 serves as a working fluid and retains the CO.sub.2 during the power generation cycle to produce mechanical energy or work, after which the CO.sub.2 is desorbed for densification and recovery as an essentially pure gas stream and the working fluid is recycled for use in the process.

Provided are a carbon dioxide absorbing composition comprising an ionic material comprising a cyclic ammonium cation and a method of separating carbon dioxide using the same, and the carbon dioxide absorbing composition of the present disclosure has high thermal and chemical stability and excellent carbon dioxide absorption effect. In addition, the method of separating carbon dioxide using the carbon dioxide absorbing composition is very effective for desorption of carbon dioxide, and is a very economical method since it allows repeated use of the carbon dioxide absorbing composition.

A process for recovery of ethylene from a polymerization product stream of a polyethylene production system, comprising separating a light gas stream from the polymerization product stream, wherein the light gas stream comprises ethane and unreacted ethylene, contacting the light gas stream with an absorption solvent system, wherein the contacting the light gas stream with the absorption solvent system occurs at a temperature in a range of from about 40 F. to about 110 F., wherein at least a portion of the unreacted ethylene from the light gas stream is absorbed by the absorption solvent system, and recovering unreacted ethylene from the absorption solvent system to yield recovered ethylene.

Non-acidic sulfur compounds can be extracted from a gas stream by contacting the gas stream with a carbonate solvent that contains at least one organic carbonate in an amount that is effective to solvate at least a portion of the non-acidic sulfur compounds. The gas steam can then be separated from the carbonate solvent that contains the non-acidic sulfur compounds. The carbonate solvent may optionally include a co-solvent and/or a mercaptan scavenger.

Capture of hydrogen sulfide from a gas mixture may be accomplished using an aqueous solution comprising an amine. Certain sterically hindered amines may selectively form a reaction product with hydrogen sulfide under kinetically controlled contacting conditions and afford a light phase and a heavy phase above a critical solution temperature, wherein the hydrogen sulfide may be present in either phase. Upon separation of the light phase from the heavy phase, processing of one of the phases may take place to remove hydrogen sulfide therefrom. Recycling of the amine to an absorber tower may then take place to promote capture of additional hydrogen sulfide.

Capture of hydrogen sulfide from a gas mixture may be accomplished using an aqueous solution comprising an amine. Certain sterically hindered amines may selectively form a reaction product with hydrogen sulfide under kinetically controlled contacting conditions and afford a light phase and a heavy phase above a critical solution temperature, wherein the hydrogen sulfide may be present in either phase. Upon separation of the light phase from the heavy phase, processing of one of the phases may take place to remove hydrogen sulfide therefrom. Recycling of the amine to an absorber tower may then take place to promote capture of additional hydrogen sulfide.

The present invention relates to a process for removing carbon dioxide from a synthesis gas having at least hydrogen and carbon dioxide in which the synthesis gas is at least partially freed of carbon dioxide in an absorption apparatus by physical absorption at elevated absorption pressure. The carbon dioxide is subsequently desorbed by pressure reduction relative to the absorption pressure in a plurality of serially arranged flash stages and an at least partially regenerated absorption medium is withdrawn from the last of the plurality of serially arranged flash stages, recompressed to absorption pressure and recycled into the absorption apparatus for use as absorption medium. It is also provided according to the invention that a partially regenerated absorption medium from a flash stage upstream of the last of the plurality of serially arranged flash stages is recompressed to absorption pressure and recycled into the absorption apparatus for use as absorption medium.

The present invention relates to a method for upgrading biogas generated by a biological process wherein at least carbon dioxide is removed from the bio-gas. More specifically the present invention relates to method for upgrading a biogas comprising a first absorption step wherein the liquid effluent is subjected to a second absorption step and a flash step and the gas streams resulting therefrom are recycled. The present invention also relates a biogas upgrading plant.