A process for recovering sulfur from a sour gas is provided. The process includes the steps of: providing the sour gas to a membrane separation unit having a carbon dioxide-selective membrane that comprises a perfluoropolymer, wherein the sour gas comprises carbon dioxide and at least 1 mol % hydrogen sulfide; separating the sour gas using the carbon dioxide-selective membrane in the membrane separation stage to obtain hydrogen sulfide-enriched gas and hydrogen sulfide-stripped gas, wherein the hydrogen sulfide-enriched gas has a hydrogen sulfide concentration of at least 20 mol %, and wherein the hydrogen sulfide-stripped gas comprises carbon dioxide; and processing the hydrogen sulfide-enriched gas in a sulfur recovery unit to obtain sulfur.

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.

Impurities that are less volatile than carbon dioxide, e.g. hydrogen sulfide, are removed from crude carbon dioxide by processes involving distillation of said crude carbon dioxide in a distillation column system operating at super-atmospheric pressure(s) to produce carbon dioxide-enriched overhead vapor and bottoms liquid enriched with said impurities. Where such processes involve a single heat pump cycle, significant savings in power consumption are realized when the distillation column system is re-boiled by at least partially vaporizing liquid in or taken from an intermediate location in the column system.

A system of enriching acid gas for feeding a sulfur recovery unit includes a contactor configured to separate an acid gas stream into a carbon dioxide rich stream and a purified acid gas stream, where the acid gas stream includes hydrogen sulfide, carbon dioxide, and hydrocarbons; a regenerator in fluid communication with the contactor such that the regenerator is configured to separate the purified acid gas stream to create a hydrogen sulfide rich stream and a hydrogen sulfide lean stream; and a recycle stream conduit fluidly coupled between the regenerator to the contactor and configured to supply at least a portion of the hydrogen sulfide rich stream from the regenerator to the contactor.

A system of enriching acid gas for feeding a sulfur recovery unit includes a contactor configured to separate an acid gas stream into a carbon dioxide rich stream and a purified acid gas stream, where the acid gas stream includes hydrogen sulfide, carbon dioxide, and hydrocarbons; a regenerator in fluid communication with the contactor such that the regenerator is configured to separate the purified acid gas stream to create a hydrogen sulfide rich stream and a hydrogen sulfide lean stream; and a recycle stream conduit fluidly coupled between the regenerator to the contactor and configured to supply at least a portion of the hydrogen sulfide rich stream from the regenerator to the contactor.

Scavenging compounds and compositions useful in reducing sulfide emissions from polymer treated asphalt, such as polyphosphoric acid, are disclosed. The scavengers include hexamethyl-enetetramine, water-free triazine, and water-free 1,3,5-triazine derivatives of formula I. Methods of using the compositions to reduce hydrogen sulfide emissions from asphalt are also disclosed.

Systems and methods for removing hydrogen sulfide from an ammonia stream in the NH3 purification and liquefaction stage of a conventional two-column sour water stripping system using an adsorbent bed.

An acid gas purification system is described herein that includes a primary membrane system with a CO.sub.2- and H.sub.2S-enriched permeate stream effluent and a hydrocarbon stream effluent; a first compression stage arranged to receive the CO.sub.2- and H.sub.2S-enriched permeate stream and produce a compressed stream; and a cryogenic separation system to receive the compressed stream, the cryogenic separation system including a cooler followed by a fractionator, wherein the fractionator produces a CO.sub.2- and H.sub.2S liquid stream and a hydrocarbon gas stream.

An acid gas purification system is described herein that includes a primary membrane system with a CO.sub.2- and H.sub.2S-enriched permeate stream effluent and a hydrocarbon stream effluent; a first compression stage arranged to receive the CO.sub.2- and H.sub.2S-enriched permeate stream and produce a compressed stream; and a cryogenic separation system to receive the compressed stream, the cryogenic separation system including a cooler followed by a fractionator, wherein the fractionator produces a CO.sub.2- and H.sub.2S liquid stream and a hydrocarbon gas stream.

A method of sulfur enriching an acid gas stream in an acid gas enrichment system includes: (i) feeding an acid gas stream to a contactor, the acid gas stream comprising hydrogen sulfide (H2S), carbon dioxide (CO2), and hydrocarbons; (ii) separating the acid gas stream in the contactor to create a carbon dioxide rich stream and a purified acid gas stream; (iii) feeding the purified acid gas stream to a regenerator fluidly connected to the contactor; (iv) separating the purified acid gas stream in the regenerator to create a hydrogen sulfide rich stream and a hydrogen sulfide lean stream, the hydrogen sulfide rich stream having a concentration of hydrogen sulfide; and (v) periodically feeding at least a portion of the hydrogen sulfide rich stream exiting the regenerator to the acid gas stream entering the contactor.