Abstract: A process for adsorption separation uses a solid IM-12 type adsorbent to separate a molecular species from any feed.

Abstract: A process for separating para-xylene from a mixture of C8 alkylaromatics comprises contacting the mixture of C8 alkylaromatics with a zeolitic binder-converted composition comprising (a) a zeolite X composition having at least a first zeolite X having a mean diameter not greater than 2.7 microns, and a second zeolite X, wherein the second zeolite X is obtained by converting a binder material to the second zeolite X and the binder material is in a range from 5 to 50 wt % of the zeolite X composition; and (b) an unconverted binder material content, after conversion to the second zeolite X is complete, in a range from 0 to 3 wt % of the zeolite X composition. The zeolite X composition has an average Si/Al framework mole ratio in a range from 1.0 to 1.5, and a relative LTA intensity not greater than 1.0, as determined by x-ray diffraction (XRD).

Abstract: The present process comprises a means for energy savings in a process pump by combining the pump with a power-recovery turbine. The invention is particularly useful in the separation of a desired product from a mixture of components using simulated-moving-bed adsorption associated with a large circulating stream with a power-recovery turbine feature for conservation of energy relative to the known art. The improvement is particularly applicable to a process for the separation of para-xylene from mixed C8 aromatics.

Abstract: The apparatus includes at least two adsorptive separation zones to separate para-xylene from a feed stream comprising C8 aromatic hydrocarbons and at least one C9 aromatic hydrocarbon component. The first adsorptive separation zone delivers a raffinate stream to a raffinate distillation zone and an extract stream to an extract distillation zone. The raffinate distillation zone delivers a stream to the second adsorptive separation zone and at least one of the extract distillation zone and raffinate distillation zone delivers a recycle stream to the first adsorptive separation zone.

Abstract: Provided is a process for crystallization separating p-xylene, comprising: a) feeding a mixed xylenes stream comprising greater than or equal to 60% by weight, of p-xylene, such as 60% to 98% by weight of p-xylene, to a crystallization unit to perform cooling crystallization, to obtain a slurry comprising p-xylene crystals; and b) feeding the slurry to a filtration and purification unit, to obtain a mother liquor, washings, and p-xylene, wherein the filtration and purification unit uses a simulated moving bed or a combination of multiple moving beds.

Abstract: The invention is an adsorptive separation process for producing a para-xylene product from a feed stream comprising para-xylene, at least one other C8 aromatic, and a C9 aromatic. An adsorbent comprising X or Y zeolite and a desorbent comprising para-diethylbenzene (p-DEB) are used in an adsorptive separation zone to produce an extract stream comprising para-xylene, p-DEB, and the C9 aromatic and a raffinate stream comprising the at least one other C8 aromatic, the C9 aromatic, and p-DEB. The extract stream is separated in an extract distillation zone to produce a second desorbent stream comprising the C9 aromatic and p-DEB and the raffinate stream is separated in a raffinate distillation zone to produce a third desorbent stream comprising the C9 aromatic and p-DEB. At least a portion of at least one of the second desorbent stream and the third desorbent stream is further separated in a desorbent distillation zone to produce a stream comprising the C9 aromatic.

Abstract: The invention relates to an improved absorption-type separation and/or purification processes having dual rotary valves.

Abstract: A process for separating a feed F by simulated moving bed adsorption in a SMB device comprises external bypass lines Li/i+1 which directly connect two successive plates, Pi, Pi+1, the index “i” being either even or (exclusive of the foregoing) odd, along the whole length of the column, allowing said plates to be flushed, in which each of the bypass lines Li/i+1 comprises automated means for regulating the flow rate in the bypass lines, the bypass lines in certain cases being subject to a flushing flow during injection or withdrawal operations.

Abstract: A process for separating a feed F by simulated moving bed adsorption in a SMB device comprises at least one zone 1 for desorption of the compounds produced in the extract, a zone 2 for desorption of the compounds produced in the raffinate, a zone 3 for adsorption of the compounds produced in the extract, a zone 4 located between the raffinate withdrawal and the desorbant supply, the device comprising external by-pass lines Li/i+1 directly connecting two successive plates Pi and Pi+1; in which the degree of opening of means for restricting the flushing flow rate of the by-pass lines Li/i+1 are sequentially modified such that: 1) in an operational zone where there is at least one closed by-pass line, a super-synchronicity of the flushing flow rate is established in all of the by-pass lines which are not closed belonging to the zone under consideration, said super-synchronicity being defined by the following formula: S=a+b(nf/nt) in which the constant a is a constant in the range ?5 to 5 and b is a constant

Abstract: A process for separating a feed F by simulated moving bed adsorption in a SMB device is described, the device comprising external bypass lines Li/i+1 which directly connect two successive plates Pi, Pi+1, the index i being either even or (exclusive of the foregoing) odd, along the whole length of the column, in order to flush said plates, in which each of the bypass lines Li/i+1 comprises automated means for regulating the flow rate in the bypass lines, the degree of opening of said regulating means being defined by the following three rules: a) establishing a flow rate corresponding to an oversynchronicity in the range 15% to 30% in all of the open bypass lines of zone 1; b) establishing a flow rate corresponding to the synchronicity to within plus or minus 8% in all of the open bypass lines of zones 2 and 3; c) establishing a flow rate corresponding to an oversynchronicity in the range 20% to 40% in all of the open bypass lines of zone 4.

Abstract: To provide a method of purifying 2,7-dimethylnaphthalene comprising the step of bringing a raw oil containing a mixture of 1,7-dimethylnaphthalene and 2,7-dimethylnaphthalene together with a developing solvent into contact with L-type zeolite to thereby effect adsorption of 1,7-dimethylnaphthalene.

Abstract: A method for separating a xylene from a feed mixture by contacting the feed mixture with a bed of adsorbent comprising metal organic framework crystals selective to the xylene.

Abstract: This invention relates to a process for conversion of hydrocarbon feedstock, comprising the steps of (A) feeding the hydrocarbon feedstock to an adsorption unit; (B) adsorbing the hydrocarbon feedstock in the adsorption unit with a solid particulate adsorbent useful for adsorbing at least one component from the hydrocarbon feedstock under adsorption conditions; (C) withdrawing the adsorbed feedstock from the adsorption unit; (D) desorbing the component(s) from the solid particulate adsorbent; and (E) removing, under the adsorption conditions for a fractional time of step (B), at least a portion of said adsorbent while the feedstock is being fed to the adsorption unit.

Abstract: Process for separation of a feedstock F by adsorption in a simulated moving bed in an SMB device that comprises a zone 1 for desorption of compounds produced by extraction, a zone 2 for desorption of compounds produced with a raffinate, a zone 3 for adsorption of compounds produced by extraction, and a zone 4 that is located between the draw-off of the raffinate and the supply of the desorbent, whereby the device comprises external bypass lines Li/i+1 directly joining two successive plates Pi, Pi+, that are equipped with non-automated means for adjusting flow rate and closing means, in which the degree of opening of the restriction means of the scavenging flow rate of the bypass lines Li/i+1 is adjusted so as to obtain the best performance of the SMB.

Abstract: A process for the combined production of para-xylene and benzene comprises: separating a first feed, by adsorption in a simulated moving bed SMB, to produce an extract E rich in para-xylene and at least one raffinate R which is depleted in para-xylene; converting a secondary feed of toluene by selective disproportionation to produce benzene and xylenes; a) at the start of the cycle, producing a supplemental quantity of para-xylene in a crystallization unit supplied with the xylenes from the disproportionation; b) at the end of the cycle, when the adsorbant has aged: dividing the distilled extract E into a first fraction Ea and a complementary second fraction Eb; replacing the feed to the initial crystallization by the stream Ea; and recycling the xylenes from the disproportionation to the SMB. The invention enables para-xylene and benzene production to be maintained despite ageing of the SMB absorbent.

Abstract: Disclosed is a method for separating aromatic compounds using a simulated moving bed (SMB) operation, characterized by injecting each raw material having a different composition into each different part of an adsorption chamber so as to improve the recovery rate. More specifically, the present invention provides a method for separating aromatic compounds for improving p-xylene separation in a p-xylene separation process, by injecting a high p-xylene mixture from selective toluene disproportionation process (STDP) and low p-xylene mixture from other processes (for example, processes of reformer, isomerization reactor and transalkylation of aromatics having 9 carbon atoms) into each different part of an adsorption chamber.

Abstract: An improved process for the production capacity and feedstock handling flexibility of a simulated moving bed adsorptive separation process by introducing a second feed stream to the adsorbent chamber comprising a feed material of a different concentration of the desired compound than the concentration of the desired compound in the first feed material stream. The introduction of this second feed material stream may be performed at any location on the adsorbent chamber between (i) a transfer point located immediately upstream of the point of the raffinate material stream withdrawal from the adsorbent chamber to (ii) a transfer point located immediately downstream of the point of extract material stream withdrawal from the adsorbent chamber. A recycle stream may be introduced into the system at a location having a concentration similar to the concentration of the first feed material stream.

Abstract: A process for the separation of close boiling compounds comprising distilling a hydrocarbon mixture of said compounds in the presence of a high boiling diluent liquid and a solid adsorbent. The high boiling diluent is withdrawn from the bottom of the distillation column and recycled to the column. The process is particularly suitable for the separation of straight-chain isomers from isomerate mixtures, the separation of benzene from hydrocarbon mixtures and the separation of paraffins from olefins.

Abstract: A process is described for the separation of a first chemical compound from a liquid feed stream comprising at least first and second chemical compounds by simulated countercurrent adsorptive separation. In the process, the feed stream and a liquid desorbent stream are passed into at least one multi-bed adsorbent chamber at two different points via different transfer lines and an extract stream rich in the first chemical compound and a raffinate stream depleted in the first chemical compound are removed from the adsorbent chamber at two different points by two additional transfer lines. In addition, the contents of the transfer line which has just been used to supply the desorbent stream are flushed into the adsorbent chamber at a point along the chamber between the transfer line just used to supply the desorbent stream and the transfer line just used to withdraw the raffinate.

Abstract: The apparatus includes at least two adsorptive separation zones to separate para-xylene from a feed stream comprising C8 aromatic hydrocarbons and at least one C9 aromatic hydrocarbon component. The first adsorptive separation zone delivers a raffinate stream to a raffinate distillation zone and an extract stream to an extract distillation zone. The raffinate distillation zone delivers a stream to the second adsorptive separation zone and at least one of the extract distillation zone and raffinate distillation zone delivers a recycle stream to the first adsorptive separation zone.

Abstract: Meta-xylene is recovered from admixture with other C8 aromatic hydrocarbons including ortho-xylene by liquid phase adsorptive separation. Performance is improved by reducing the concentration of ortho-xylene through adding a sidecut to a prefractionator preparing the feedstock to adsorptive separation.

Abstract: The invention concerns a process for producing high purity meta-xylene, comprising a step for separation by simulated moving bed adsorption starting from an aromatic C8 feed delivering a fraction which is rich in meta-xylene and a fraction which is depleted in meta-xylene, and a step for crystallization of the meta-xylene rich fraction. The purity of the meta-xylene produced is at least 99.5%.

Abstract: A process for producing para-xylene from a hydrocarbon feed is described in which an adsorption column operating as a simulated moving bed with at least five zones delivers an extract, a 2-raffinate and an intermediate raffinate. The extract is distilled and the distillate is optionally re-crystallized to recover para-xylene with a purity of at least 99.7%. The 2-raffinate is distilled then isomerized in a reactor preferably operating in the liquid phase and at a low temperature. The intermediate raffinate with an enriched ethylbenzene content is distilled then isomerized in the vapour phase.

Abstract: The process includes at least two adsorptive separation zones to separate para-xylene from a feed stream comprising C8 aromatic hydrocarbons and at least one C9 aromatic hydrocarbon component. An adsorbent comprising X or Y zeolite and a heavy desorbent are used in the first adsorptive separation zone to produce an extract stream comprising para-xylene and a raffinate stream comprising para-xylene depleted C8 aromatic hydrocarbons, the C9 aromatic hydrocarbon, and the desorbent. The raffinate stream is separated in a raffinate distillation zone to produce a stream comprising the first desorbent component and the C9 aromatic hydrocarbon which stream is further separated in a second adsorptive distillation zone to produce a stream comprising the desorbent and a C9 aromatic hydrocarbon stream.

Abstract: Process for separation of metaxylene, with at least 99% by weight of purity of an aromatic feedstock F, in a single adsorption stage in a simulated moving bed in an SMB device that comprises 12, 13 or 15 adsorbent beds with different numbers of beds being employed in zone 1 between the supply of the desorbent D and the draw-off of the extract E; zone 2 between the draw-off of the extract E and the supply of the feedstock F; zone 3 between the supply of the feedstock and the draw-off of the raffinate R; and zone 4 between the draw-off of the raffinate R and the supply of the desorbent D whereby the process is carried out according to a configuration of zones (a, b, c, d), whereby a, b, c, and d represent the number of adsorbent beds that operate respectively in zones 1, 2, 3, 4 in which there is used: Either an SMB of 12 adsorbent beds operating according to the configuration (2, 5, 3, 2), Or an SMB of 13 adsorbent beds operating according to the configuration (2, 5, 4, 2), Or an SMB of 15 adsorbent beds op

Abstract: Adsorbents and methods for the adsorptive separation of para-xylene from a mixture containing at least one other C8 aromatic hydrocarbon (e.g., a mixture of ortho-xylene, meta-xylene, para-xylene, and ethylbenzene) are described. Suitable binderless adsorbents (e.g., formulated with the substantial absence of an amorphous material that normally reduces selective pore volume), particularly those with a water content from about 3% to about 5.5% by weight, improve capacity and/or mass transfer. These properties are especially advantageous for improving productivity in low temperature, low cycle time adsorptive separation operations in a simulated moving bed mode.

Abstract: Adsorbents and methods for the adsorptive separation of para-xylene from a mixture containing at least one other C8 aromatic hydrocarbon (e.g., a mixture of ortho-xylene, meta-xylene, para-xylene, and ethylbenzene) are described. Suitable adsorbents comprise small-crystallite-size zeolite X having an average crystallite size of less than 1.8 microns. The adsorbents may be binderless (e.g., formulated with the substantial absence of an amorphous material that normally reduces selective pore volume) to further improve capacity and mass transfer. These properties are especially advantageous for improving productivity in low temperature, low cycle time adsorptive separation operations in a simulated moving bed mode.

Abstract: This invention relates to a process for conversion of hydrocarbon feedstock, comprising the steps of (A) feeding the hydrocarbon feedstock to an adsorption unit; (B) adsorbing the hydrocarbon feedstock in the adsorption unit with a solid particulate adsorbent useful for adsorbing at least one component from the hydrocarbon feedstock under adsorption conditions; (C) withdrawing the adsorbed feedstock from the adsorption unit; (D) desorbing the component(s) from the solid particulate adsorbent; and (E) removing, under the adsorption conditions for a fractional time of step (B), at least a portion of said adsorbent while the feedstock is being fed to the adsorption unit.

Abstract: This invention relates to a process for conversion of hydrocarbon feedstock, comprising the steps of (A) feeding the hydrocarbon feedstock to an adsorption unit; (B) adsorbing the hydrocarbon feedstock in the adsorption unit with a solid particulate adsorbent useful for adsorbing at least one component from the hydrocarbon feedstock under adsorption conditions; (C) withdrawing the adsorbed feedstock from the adsorption unit; (D) desorbing the component(s) from the solid particulate adsorbent; and (E) removing, under the adsorption conditions for a fractional time of step (B), at least a portion of said adsorbent while the feedstock is being fed to the adsorption unit.

Abstract: Process for separating paraxylene with a purity that is at least equal to 99.5% by weight from an aromatic feedstock F in a single adsorption stage in a simulated moving bed (SMB), comprising different numbers of beds, allocated to a zone 1 between the supply of the desorbent D and the draw-off of the extract E; a zone 2 between the draw-off of the extract E and the supply of the feedstock F; a zone 3 between the supply of the feedstock and the draw-off of the raffinate R; a zone 4 between the draw-off of the raffinate R and the supply of the desorbent D, wherein an SMB of 12 adsorbent beds has bed configuration (2, 5, 3, 2), an SMB of 15 adsorbent beds has bed configuration (3, 6, 4 , 2), or an SMB of 19 adsorbent beds has bed configuration (4, 7, 6, 2), wherein the desorbent in this latter case is paradiethylbenzene.

Abstract: Adsorbents and methods for the adsorptive separation of meta-xylene from a mixture containing at least one other C8 aromatic hydrocarbon (e.g., a mixture of ortho-xylene, meta-xylene, para-xylene, and ethylbenzene) are described. Suitable adsorbents comprise sodium zeolite Y having an average crystallite size from about 50 to about 700 nanometers. The adsorbents provide improved separation efficiency, which may be associated with a higher meta-xylene mass transfer rate and/or other beneficial effects. Exemplary desorbents for use in the process may comprise toluene, benzene, or indan.

Abstract: The invention concerns a process for separating meta-xylene from a hydrocarbon feed comprising isomers containing 8 carbon atoms, comprising: a step for bringing said feed into contact with a faujasite type zeolite adsorbant, the percentage of water in the adsorbant being in the range 0 to 8% by weight and the adsorption temperature being from 25° C. to 250° C.; a desorption step employing a solvent selected from tetraline and its alkylated derivatives; a step for separating meta-xylene from the desorbant.

Abstract: The present invention relates to agglomerated zeolitic adsorbents based on zeolite X with an Si/Al ratio such that 1.15<Si/AL<1.5, consisting of crystals with a mean diameter of 1.7 mm or less and of an inert binder, at least 90% of the exchangeable cationic sites of the zeolite X being occupied by barium ions. They may be obtained by agglomerating a zeolite X powder having a mean diameter of 1.7 mm or less with a binder, followed by zeolitization of the binder, exchange of the zeolite ions with barium (and potassium) ions and activation of the adsorbents thus exchanged.

Abstract: In a process for producing a para-xylene enriched product from a gaseous mixture comprising at least para-xylene, meta-xylene and ortho-xylene, the gaseous mixture is contacted with an adsorbent capable of selectively adsorbing para-xylene and comprising a crystalline molecular sieve having an average crystal size between about 0.5 micron and about 20 microns. The contacting is conducted at a temperature and pressure such that at least part of the para-xylene in the mixture is adsorbed by the adsorbent to produce a para-xylene-depleted effluent stream. The para-xylene is then desorbed from said adsorbent and collected to form a para-xylene enriched stream. The adsorption and desorption steps are repeated for a plurality of cycles, such that the time between successive contacting steps is no more than 10 seconds.

Abstract: Provided is a process for adsorptive separation of p-xylene from an aromatic hydrocarbon mixture comprising other isomers of xylene, and a device used therein. More specifically, the present invention provides a separation process employing simulated moving bed (SMB) adsorptive chromatography, characterized by subjecting the extracts eluted from a plurality of adsorption chambers arranged in parallel, to a crystallizer for additional separation, thereby improving productivity, and a device used therein.

Abstract: Adsorbents and methods for the adsorptive separation of meta-xylene from a mixture containing at least one other C8 aromatic hydrocarbon (e.g., a mixture of ortho-xylene, meta-xylene, para-xylene, and ethylbenzene) are described. Suitable adsorbents comprise sodium zeolite Y having an average crystallite size from about 50 to about 700 nanometers. The adsorbents provide improved separation efficiency, which may be associated with a higher meta-xylene mass transfer rate and/or other beneficial effects. Exemplary desorbents for use in the process may comprise toluene, benzene, or indan.

Abstract: Adsorbents and methods for the adsorptive separation of para-xylene from a mixture containing at least one other C8 aromatic hydrocarbon (e.g., a mixture of ortho-xylene, meta-xylene, para-xylene, and ethylbenzene) are described. Suitable adsorbents comprise zeolite X having an average crystallite size of less than 1.8 microns. The adsorbents provide improved mass transfer, which is especially advantageous for improving productivity in low temperature, low cycle time adsorptive separation operations in a simulated moving bed mode.

Abstract: A process for separating C8 aromatics is disclosed. The process uses at least two adsorbents, and in particular a BaX zeolite and a KY zeolite, for the separation of para-xylene from a mixture of C8 aromatics.

Abstract: Provided is a process for adsorptive separation of p-xylene from an aromatic hydrocarbon mixture comprising other isomers of xylene, and a device used therein. More specifically, the present invention provides a separation process employing simulated moving bed (SMB) adsorptive chromatography, characterized by pretreating a fluid mixture, i.e. the feed, by using single adsorption chamber so as to raise the concentration of a component to be separated, and then carrying out the simulated moving bed adsorptive separation, thereby improving productivity, and a device used therein.

Abstract: A process for co-producing para-xylene and styrene from a feed (1) of hydrocarbons containing xylenes and ethylbenzene is described, the process comprising the following succession of steps: a step for separating the feed in a simulated moving bed in an adsorption column (6) containing beds of an adsorbent, from which an extract that is rich in para-xylene (7a) of at least 99.7% purity and at least one raffinate (7b) containing ethylbenzene, ortho-xylene, meta-xylene and a very small quantity of para-xylene is withdrawn; a step for dehydrogenating (10) the ethylbenzene contained in the raffinate (7b) to styrene; at least one step for primary separation of the stream (11) from the dehydrogenation step (10), to eliminate by-products; a step for separating the purified mixture (18) derived from the stream (11) containing styrene, unconverted ethylbenzene, meta-xylene and ortho-xylene, from which a stream (21a) that is rich in styrene of at least 99.

Abstract: Use of mordenite zeolite and zeolite Y as adsorbents enables a dimethylnaphthalene isomer mixture to be efficiently separated. A feedstock oil containing a dimethylnaphthalene isomer mixture including an ?,?-isomer, an ?,?-isomer, and a ?,?-isomer is passed through an adsorbent layer (A) including mordenite zeolite together with a developing solvent. Subsequently, a liquid discharged from the adsorbent layer (A) is passed through an adsorbent layer (B) including zeolite Y. An eluent is passed through the adsorbent layer (B). The solvent is removed from the resultant eluate to obtain the ?,?-isomer of dimethylnaphthalene. Similarly, the ?,?-isomer of dimethylnaphthalene is obtained from the adsorbent layer (A).

Abstract: The invention concerns a process for separating meta-xylene from a hydrocarbon feed comprising isomers containing 8 carbon atoms, comprising: a step for bringing said feed into contact with a faujasite type zeolite adsorbant, the water content of the adsorbant being in the range 0 to 1% by weight and the adsorption temperature being from 160° C. to 180° C.; a desorption step employing a solvent selected from toluene, indane and mixtures thereof.

Abstract: The present invention discloses a means to improve the production capacity and feedstock handling flexibility of a simulated moving bed adsorptive separation process by introducing a second feed stream to the adsorbent chamber, such second feed stream comprising a feed material of a different concentration of the desired compound than the concentration of such desired compound in the first feed material stream. The introduction of this second feed material stream may be performed at any location on the adsorbent chamber between (i) a transfer point located immediately upstream of the point of the raffinate material stream withdrawal from the adsorbent chamber to (ii) a transfer point located immediately downstream of the point of extract material stream withdrawal from the adsorbent chamber. The specific transfer point used for the introduction of the second feed material stream will depend upon the concentration of the desired component in the second feed material stream.

Abstract: Disclosed herein is an improved method for making and obtaining para-xylene from a mixture of xylene isomers, and various embodiments of the method. The method generally includes contacting a mixture comprising xylene isomers and ethylbenzene with a para-xylene selective adsorbent to obtain a para-xylene depleted raffinate, and a desorption effluent comprising a para-xylene enriched product. The method also includes isomerizing the para-xylene depleted raffinate. The contacting step is carried out in a manner such that the raffinate need not be pressurized prior to isomerization, thus advantageously obviating expensive compression steps.

Abstract: A process and a system for increasing para-xylene production from a C8 aromatic feedstream by coupling at least one xylene isomerization reactor with at least one pressure swing adsorption unit or temperature swing absorption unit to produce a product having a super-equilibrium para-xylene concentration. This product is then subjected to para-xylene separation and purification.

Abstract: Product purity from or capacity of a simulated-moving-bed adsorptive separation process is increased by flushing the contents of the transfer line previously used to remove the raffinate stream away from the adsorbent chamber, preferably into the raffinate column used to separate desorbent from raffinate product. Preferably a stream from the adsorbent chamber at an intermediate point between the feed entry point and raffinate withdrawal is used as the flushing liquid. This flush step eliminates the passage of a quantity of the raffinate material into the adsorbent chamber in the transfer-line flush period or when the process conduit is subsequently used to charge the feed stream to the adsorbent chamber.

Abstract: Method of optimizing the operation of a unit intended for separation of the components of a feed (xylenes) by simulated countercurrent in hybrid operating mode. The method allows to minimize the solvent ratio and to maximize the capacity of the separation unit while keeping product specifications such as purity and yield constant. It has been verified that these two objectives cannot be reached simultaneously and it is recommended to operate with a minimum solvent ratio while guaranteeing a high capacity compatible with stable operation of the separation unit. These optimization objectives are reached while keeping good stability around the optimum point thus defined, by using a known operation control process such as the one described in patent EP-875,268 for example.

Abstract: A process for separating mixtures of hydrocarbon isomers on molecular sieves, including providing columns which include molecular sieves and function alternatively as secondary adsorption, primary adsorption, and desorption devices, feeding the mixtures of hydrocarbon isomers to a column functioning as the primary adsorption device for adsorbing isomers with greater selectivity towards the molecular sieves, feeding effluent of the mixtures from the column functioning as the primary adsorption device to a column functioning as the secondary adsorption device for adsorbing remaining isomers with greater selectivity, discharging isomers with a lower selectivity from the column functioning as the secondary adsorption device and a desorbing agent therein, feeding a desorbing agent to the column functioning as the desorption device, discharging isomers with a greater selectivity towards the molecular sieves and the desorbing agent in the column functioning as the desorption device.

Abstract: The present invention relates to agglomerated zeolitic adsorbents based on zeolite X with an Si/Al ratio such that 1.15<Si/Al?1.5, at least 90% of the exchangeable cationic sites of the zeolite X of which are occupied either by barium ions alone or by barium ions and potassium ions whose Dubinin volume is greater than or equal to 0.240 cm3/g. They are obtained by agglomerating zeolite powder with a binder, followed by the zeolitization of the binder, the exchange of the ions of the zeolite by barium ions (and potassium ions) and the activation of the adsorbents thus exchanged. These adsorbents are particularly suited to the adsorption of the para-xylene present in C8 aromatic hydrocarbon fractions in the liquid phase in processes of simulated moving bed type but also to the separation of sugars, polyhydric alcohols, cresols or substituted toluene isomers.

Abstract: A process and a system for increasing para-xylene production from a C8 aromatic feedstream by coupling at least one xylene isomerization reactor with at least one pressure swing adsorption unit or temperature swing absorption unit to produce a product having a super-equilibrium para-xylene concentration. This product is then subjected to para-xylene separation and purification.