The invention relates to a gas scrubbing process and plant for purifying raw synthesis gas by physical absorption in methanol. A raw synthesis gas stream which includes hydrogen and carbon monoxide as desired constituents and water and acid gases as undesired constituents is admixed with methanol and subsequently cooled below the freezing point of water. According to the invention a liquid phase including methanol and water is separated from the cooled raw synthesis gas stream. Acid gases are removed from the remaining gaseous phase by physical absorption in methanol at elevated pressure. Separating the water from the raw synthesis gas stream before the absorption of the acid gases prevents larger amounts of water passing into the methanol circuit of the gas scrubbing process. This achieves savings in resources and certain plant parts may be smaller than is customary.

This disclosure provides a method for treating natural gas comprising causing at least some of a sour natural gas stream comprising hydrocarbon gas and hydrogen sulfide to contact an amine or pass through a separation system. A sweet natural gas stream comprising hydrocarbon gas and a waste gas stream comprising hydrogen sulfide are formed by contacting the sour natural gas with an amine or by passing it though a separation device. At least some of the hydrogen sulfide in the waste gas stream is oxidized, forming an exhaust gas stream comprising sulfur dioxide, which is then contacted with water or reactant and water solution or slurry to destroy or convert SO.sub.2 into a less environmentally harmful compound.

A system for scrubbing and monitoring H2S includes: a sample inlet valve that controls an input stream of the hydrocarbon gas from the gas canister; a first scrubber that removes a first portion of H2S from the input stream and that outputs a first stream with less H2S than the input stream; a second scrubber that removes a second portion of H2S from the first stream and that outputs a second stream with less H2S than the first stream; a H2S converter that converts all remaining H2S in the second stream into a di-ketone and that outputs an output stream with a concentration of the di-ketone; an optical detector that measures the concentration of the di-ketone in the output stream; and a processor that determines a concentration of H2S in the second stream based on the concentration of the di-ketone in the output stream.

In a process for removal of acid gases from a fluid stream the fluid stream is contacted with an absorbent to obtain a treated fluid stream and a laden absorbent. The absorbent comprises a diluent and a compound of the general formula (I) wherein R.sup.1 is C.sub.1-C.sub.3-alkyl; R.sup.2 is C.sub.1-C.sub.3-alkyl; R.sup.3 is selected from hydrogen and C.sub.1-C.sub.3-alkyl; and R.sup.4 is selected from hydrogen and C.sub.1-C.sub.3-alkyl. ##STR00001##

Disclosed is a process for regenerating a hybrid solvent used to remove contaminants from a fluid stream and to provide an improved yield of purified fluid. Said process comprises a purification unit (12) and at least one regeneration unit (40) wherein make-up water (72) is added to the regenerated lean hybrid solvent (55) prior to reuse in the first purification unit and no water is recycled into the regeneration unit.

Provided herein a process for purification of an ionic liquid from heavy metals, comprising combining heavy metal-containing ionic liquid and a sulfide source to form heavy metal sulfide, and separating said heavy metal sulfide from the ionic liquid.

A system and method for processing unconditioned syngas first removes solids and semi-volatile organic compounds (SVOC), then removes volatile organic compounds (VOC), and then removes at least one sulfur containing compound from the syngas. Additional processing may be performed depending on such factors as the source of syngas being processed, the products, byproducts and intermediate products desired to be formed, captured or recycled and environmental considerations.

Various hydrogels are described which are useful for the regeneration of methyldiethanolamine which is used to scrub H.sub.2S/CO.sub.2. Methods of regenerating methyldiethanolamine using such hydrogels are also described.

The invention relates to a process and a plant for removing thiols from synthesis gas. Thiols and optionally thiophene and carbon disulfide are absorbed in a dedicated absorption stage with methanol as physical absorption medium. Methanol laden with at least thiols is freed of thiols in a stripping stage with methanol vapours as stripping gas and the methanol vapours-containing thiols are freed of methanol in a scrubbing stage. The process according to the invention minimizes methanol losses and the amounts of coolant required for the process.

Hydrogen sulfide is removed from a gas stream by bubbling a gas stream having ≥100 ppm hydrogen sulfide through a scavenging mixture. The scavenging mixture includes: 1) at least one sweetener selected from the group consisting of triazines, oxazolidines, hemiacetals, and mixtures thereof, and 2) at least one reaction catalyst selected from the group consisting of dipropyl amine (DPA), diethyl amine (DEA), dimethyl amine (DMA), pyrrole, and mixtures thereof. The scavenging mixture interacts with the hydrogen sulfide to produce a cleaned gas stream having ≤ 5 ppm hydrogen sulfide.