A process and system for separating butenes and butanes by extractive distillation using a polar solvent is disclosed. The process may include: contacting a hydrocarbon mixture including butanes and butenes with a lean solvent mixture in an extractive distillation column to form an enriched solvent fraction comprising butenes; recovering an overheads fraction comprising butanes and a bottoms fraction from the extractive distillation column; feeding the bottoms fraction to a stripper including a stripping section and a wash section; recovering the lean solvent mixture as a bottoms fraction and a stripper overheads fraction comprising butenes and water from the stripper; condensing the overheads fraction to form a water fraction and a product butenes fraction; feeding water as reflux to a top of the stripper wash section; feeding at least a portion of the condensed water fraction intermediate the top and bottom of the stripper wash section as a second reflux.

A process and system for separating butenes and butanes by extractive distillation using a polar solvent is disclosed. The process may include: contacting a hydrocarbon mixture including butanes and butenes with a lean solvent mixture in an extractive distillation column to form an enriched solvent fraction comprising butenes; recovering an overheads fraction comprising butanes and a bottoms fraction from the extractive distillation column; feeding the bottoms fraction to a stripper including a stripping section and a wash section; recovering the lean solvent mixture as a bottoms fraction and a stripper overheads fraction comprising butenes and water from the stripper; condensing the overheads fraction to form a water fraction and a product butenes fraction; feeding water as reflux to a top of the stripper wash section; feeding at least a portion of the condensed water fraction intermediate the top and bottom of the stripper wash section as a second reflux.

A process for removing acetaldehyde efficiently and producing high-purity acetic acid stably is provided. Methanol is allowed to continuously react with carbon monoxide in a carbonylation reactor 1 in the presence of a catalyst system; the reaction mixture is continuously fed to a flasher 2 to form a volatile phase (2A) containing acetic acid and methyl iodide; the volatile phase (2A) is continuously fed to a splitter column 3 to form an overhead (3A) containing methyl iodide and acetaldehyde and a stream (3B) containing acetic acid; the volatile phase (2A) and/or the overhead (3A) is cooled by a first condenser C1, C3 at a predetermined cooling temperature; and the noncondensed gaseous component is further cooled by a second condenser C2, C4 to form a concentrate having a lower temperature and a higher acetaldehyde concentration. Acetaldehyde is efficiently removed by distilling the concentrate having a high acetaldehyde concentration.

A process for removing acetaldehyde efficiently and producing high-purity acetic acid stably is provided. Methanol is allowed to continuously react with carbon monoxide in a carbonylation reactor 1 in the presence of a catalyst system; the reaction mixture is continuously fed to a flasher 2 to form a volatile phase (2A) containing acetic acid and methyl iodide; the volatile phase (2A) is continuously fed to a splitter column 3 to form an overhead (3A) containing methyl iodide and acetaldehyde and a stream (3B) containing acetic acid; the volatile phase (2A) and/or the overhead (3A) is cooled by a first condenser C1, C3 at a predetermined cooling temperature; and the noncondensed gaseous component is further cooled by a second condenser C2, C4 to form a concentrate having a lower temperature and a higher acetaldehyde concentration. Acetaldehyde is efficiently removed by distilling the concentrate having a high acetaldehyde concentration.

Processes for separating conjunct polymer from an organic phase are described. A mixture comprising an ionic liquid phase and the organic phase into the ionic phase and an organic phase comprising the conjunct polymer and at least one silyl or boryl compound. The organic phase is separated in a fractionation column into an overhead fraction comprising unreacted silane or borane compound and a bottoms fraction comprising the conjunct polymer and the silyl or boryl compound. The bottoms fraction is passed through an adsorption zone, and the silyl or boryl compound is recovered. Alternatively, the organic phase is passed through an adsorption zone first to remove the conjunct polymer and then a fractionation zone to separate the unreacted silane or borane compound from the silyl or boryl compound.

A system for reducing dioxygen (O.sub.2) present in vapors from oil storage tanks. The system may include an inlet that receives vapors from the tanks; a heating device coupled with the inlet that heats vapors to a first temperature to form heated vapor; and a vessel coupled receiving heated vapor and containing at least one catalyst to reduce dioxygen from the heated vapor. The catalyst may include palladium, and the vessel may include zinc oxide to remove sulfur from the heated vapor. A compressor may be used to compress the vapors. A controller may be provided to monitor O.sub.2 concentration in heated vapor, and the controller directs flow of heated vapor to a gas pipeline if the O.sub.2 concentration is below a predetermined level; or if the O.sub.2 concentration is unacceptably high, the controller directs flow of vapor to be re-circulated within the system to further reduce O.sub.2 concentration therein.

A process for recovering 1,3-butadiene from a C.sub.4 fraction, where the butadiene extraction processes may be operated at an intermediate pressure using a liquid ring type compressor. The use of a liquid ring compressor, among other process options presented herein, may advantageously reduce capital and operating costs, similar to the compressorless option, while mitigating the risks associated with the higher operating temperatures and pressures associated with the compressorless option. Thus, the embodiments of the processes disclosed herein encompass the best features of the conventional design (low pressure, with a compressor) with the advantages of the compressorless design (low capital and operating cost), as well as other advantages unique to the systems disclosed herein.

A process for recovering 1,3-butadiene from a C.sub.4 fraction, where the butadiene extraction processes may be operated at an intermediate pressure using a liquid ring type compressor. The use of a liquid ring compressor, among other process options presented herein, may advantageously reduce capital and operating costs, similar to the compressorless option, while mitigating the risks associated with the higher operating temperatures and pressures associated with the compressorless option. Thus, the embodiments of the processes disclosed herein encompass the best features of the conventional design (low pressure, with a compressor) with the advantages of the compressorless design (low capital and operating cost), as well as other advantages unique to the systems disclosed herein.

Ethylbenzene can be separated from a C8 aromatics mixture containing ethylbenzene and a close boiling compound by extractive distillation using an extractive agent comprising a mixture of a chlorinated aromatic compound and another compound selected from furandione derivatives and organic nitriles.

Process for the distillative separation of ethylbenzene from a mixture comprising ethylbenzene and at least one other C8 aromatic compound, comprising distilling said mixture in a distillation column in the presence of an extractive solvent, characterized in that the distillation column is operated at a sub-atmospheric pressure.