The present invention concerns a process and system for producing and isolating a fraction of monocyclic aromatic compounds from a gasification gas. The process comprises (a) contacting the gas with a catalyst capable of converting ethylene and possibly other unsaturated hydrocarbons into monocyclic aromatic compounds; and (b) isolating monocyclic aromatic compounds from the gas originating from step (a). The present invention is ideally suited for treatment of gas from coal, biomass or waste gasification, which comprises substantial amounts of ethylene as well as monocyclic aromatic compounds. Treatment according to the invention first converts the ethylene into further monocyclic aromatic compounds, and the entire fraction of monocyclic aromatic compounds is isolated to obtain a valuable product.

Systems and methods for separating a mixture comprising C.sub.4 hydrocarbons and a solvent have been disclosed. The mixture is produced as a bottom stream of a rectifier column. The mixture is processed in at least two heating and flash-evaporating cycles to remove at least some C.sub.4 hydrocarbons as vapor streams. The resulted liquid stream is further degassed in a degasser column to produce a recycle vapor stream and a lean solvent stream.

Plant and method for the separation of a gas mixture containing a plurality of gaseous components, comprising first and second membrane-based separation stages and a third gas separation stage with adsorption with oscillating pressure, the first, second and third gas separation stages acting in combination to obtain a first final flow of gas enriched in a first component of the initial gas mixture, for example methane, and a second final flow of gas, enriched in a second component of the initial gas mixture, for example carbon dioxide.

The invention is directed to a combined naphtha hydrotreating (NHT) and isomerization process scheme, which includes dividing wall columns (DWC) that replace multiple distillation columns and allow optimized heat integration within the system. The disclosed design provides reductions in both capital and energy costs compared to conventional schemes.

A method for the production of a fuel additive includes passing a hydrocarbon stream comprising crude mixed C4 hydrocarbons through a first hydrogenation unit to produce a first product stream; passing the first product stream from the first hydrogenation unit to a methyl tert-butyl ether synthesis unit forming methyl tert-butyl ether and a byproduct stream; passing the byproduct stream through a first distillation unit to separate the byproduct stream into a first 1-butene stream, an isobutane stream, and a 2-butene and n-butane stream; forming a second product stream by passing the 2-butene and n-butane stream to a selective conversion unit; passing the second product stream into a second distillation unit to form an n-butane stream and a second 1-butene stream; passing the second 1-butene stream to a fuel additive production unit; and passing the first 1-butene stream to the fuel additive production unit to form the fuel additive.

A process for preparing a purified benzene composition from a crude hydrocarbon stream containing at least 10% by volume of benzene is provided. The process comprises subjecting the crude hydrocarbon stream and a further recycled benzene containing stream to a solvent-based extraction so as to produce a benzene enriched aromatic stream and a benzene depleted non-aromatic stream, subjecting the benzene enriched aromatic stream to a hydrodesulfurization so as to obtain a desulfurized aromatic stream, subjecting the desulfurized aromatic stream to a distillation producing a purified benzene stream and a further benzene containing stream having a benzene concentration of between less than 100% by weight and the azeotropic benzene concentration, and at least partially recycling the further benzene containing stream.

A method for separating and refining 1-butene with a high purity and a high yield from a raffinate-2 stream. The method includes: feeding raffinate-2 to a first distillation column; obtaining heavy raffinate-3 from a lower part of the first distillation column; recovering an upper part fraction containing 1-butene from an upper part of the first distillation column; feeding the upper part fraction containing 1-butene to a second distillation column; recovering a first lower part fraction rich in 1-butene from a lower part of the second distillation column and light raffinate-3 from an upper part of the second distillation column. Heat of the upper part fraction recovered from the upper part of the first distillation column is fed to the lower part of the second distillation column through a first heat exchanger. Thus, 1-butene is obtained with high purity and high yield while maximizing an energy recovery amount by double-effect distillation.

A method and system for separating light hydrocarbons are disclosed, wherein the method comprises compression, cooling, absorption, desorption, rectification, cracking, and recycling cracked gas to the compression step.

A process, a system, and an apparatus for separation of an oxygenate from a stream is provided. More specifically, a stream comprising the oxygenate is introduced to a quench tower along with a caustic outlet stream comprising a metal salt. Contact between the oxygenate and the metal salt results in conversion of a portion of the oxygenate into a derivative salt. The derivative salt and unconverted oxygenate are condensed by quenching and substantially removed from the quench tower as an oxygenate outlet stream. The gaseous components of the stream, minus a substantial portion of the oxygenate, are removed from the quench tower as a quench outlet stream.

Disclosed are a facility and a method using the facility for treating a feed gas stream comprising at least methane and carbon dioxide by membrane permeation, the facility comprising: —a first membrane separation unit capable of receiving the feed gas stream and providing a first permeate and a first retentate, —a second membrane separation unit capable of receiving the first retentate and providing a second permeate and a second retentate, —a compressor for compressing the first permeate to a pressure of between 17 bar and 25 bar, —a means for cooling the first compressed permeate to a temperature lower than −40° C., —a distillation column for separating the first cooled permeate into a gas stream and a liquid stream, —at least one means for recycling the gas stream exiting the distillation column to the inlet of the first membrane separation unit, —a means for measuring the concentration of methane and/or carbon dioxide in the gas stream exiting the distillation column, —a means for comparing the concentration of methane and/or carbon dioxide measured by the measurement means with a target value, and —a means for adjusting the pressure and/or the temperature of the first permeate depending on the comparison carried out by the comparison means.