The present invention relates to a zeolite-based adsorbent comprising at least one zeolite of FAU structure of LSX type and comprising barium and/or potassium, in which the outer surface area of said zeolite-based adsorbent, measured by nitrogen adsorption, is between 20 m.sup.2.Math.g.sup.−1 and 100 m.sup.2.Math.g.sup.−1, limits inclusive. The present invention also relates to the use of such a zeolite-based adsorbent as an adsorption agent, and also to the process for separating para-xylene from aromatic isomer fractions containing 8 carbon atoms.

Described herein is a method of adjusting the composition of a chromatography product to achieve a target enriched proportion of a desired component from an input feed having a lower proportion of the desired component using simulated moving bed (“SMB”) chromatography wherein the eluent for the SMB apparatus may comprise the very input feed being enriched. The method is exemplified by enriching a high fructose corn syrup from a 42% fructose syrup to a 55% fructose syrup without substantially reducing the dissolved solids concentration of the 55% syrup relative to the input 42% syrup. The 42% syrup is also used as the eluent for the SMB apparatus and may be reconstituted from the raffinate stream by passing the raffinate stream over a glucose isomerase column alone or in combination with a dextrose feed. The method reduces water usage and saves energy by minimizing the need for evaporation to obtain a 55% fructose syrup with a high dissolved solids content.

A process is described for separating paraxylene from a multicomponent fluid mixture of C.sub.8 aromatics. A mixture of C.sub.8 aromatics is fed to a simulated moving bed adsorptive apparatus having at least two sieve chambers and at least two rotary valves. Each sieve chamber may be operated individually using the PowerFeed process. The flow rates of the streams to or from the individual sieve chambers may be varied during the step time in an inverse manner such that a substantially constant flow to and from the apparatus is achieved. Alternatively, the flow rates to each sieve chamber may vary during the step time according to the same profile, but the rotary valves may be off-set and step independently in a staggered manner to achieve a substantially constant flow of a stream to or from the apparatus.

The present invention describes a process for obtaining para-xylene from a feedstock containing xylenes, ethylbenzene and C9+ hydrocarbons, said process comprising a single stage A of separation in a simulated moving bed carried out with a zeolite as adsorbent and a desorbent and making it possible to obtain at least three fractions, a fraction A1 comprising a mixture of para-xylene and of desorbent and two fractions A21, A22 comprising ethylbenzene (EB), ortho-xylene (OX) and meta-xylene (MX) and desorbent, said stage is carried out at a temperature between 20° C. and 250° C., under a pressure between the bubble pressure of the xylenes at the operating temperature and 2.0 MPa, and with a ratio by volume of the desorbent to the feedstock in the unit for separation 2 in a simulated moving bed is between 0.4 and 2.5, a stage B of fractionation by distillation in a 2-cut distillation column of the fractions A21 and A22 resulting from stage A, in which said fractions are introduced separately at distinct injection points, and makes it possible to obtain a fraction B2 containing ethylbenzene, ortho-xylene and meta-xylene, and a fraction B42 devoid of aromatic compounds having 8 carbon atoms and containing desorbent.

An adsorptive separation process and system are used for separation of multi-component fluid mixtures. The separation process and system may include establishing, in a fluid flow within the system, a concentration distribution of the fluid mixture components based upon the components' relative affinities to the adsorbent. The concentration distribution could be establishing using a simulated moving bed system, wherein it is possible to maintain separately-identifiable portions of the fluid flow, respectively rich in strongly-adsorbing, intermediately-adsorbing, and weakly-adsorbing compounds of the fluid mixture. An intermediate raffinate of high purity in the intermediately-adsorbing compound is directly withdrawn from the portion of the fluid flow rich in intermediately-adsorbing compound(s), providing a single-stage adsorptive separation of a compound having intermediate affinity to the adsorbent. The portion of the fluid flow rich in intermediately-adsorbing compound(s) may be established directly upstream from the point of fluid mixture feed injection into the fluid flow.

A simulated moving-bed type chromatographic separation method separating a weakly adsorptive component, a strongly adsorptive component, and an intermediately adsorptive component, with eluents by using a circulation system in which a plurality of unit packed columns packed with an adsorbent are connected in series and in an endless form via pipes in which a feed solution supply port F, two or more eluent supply ports D corresponding to the eluents, an extraction port A of a fraction containing the weakly adsorptive component, an extraction port B of a fraction containing the intermediately adsorptive component, and an extraction port C of a fraction containing the strongly adsorptive component are provided in the pipes of the circulation system, and positions of the ports F, A, B, and C are set to have a specified relationship.

The invention relates to zeolitic absorbents based on at least one zeolite with hierarchical porosity, containing barium or barium and potassium, to the uses thereof for separating para-xylene from aromatic fractions containing 8 carbon atoms, and to the method for separating para-xylene from aromatic fractions containing 8 carbon atoms.

The present invention provides a chromatographic separation process for recovering a polyunsaturated fatty acid (PUFA) product from a feed mixture, which process comprises passing the feed mixture through one or more chromatographic columns containing, as eluent, an aqueous organic solvent, wherein the temperature of at least one of the chromatographic columns through which the feed mixture is passed is greater than room temperature.

Method for the simulated moving bed (SMB) separation of a feedstock (F), in which: at least one zone (1, 2, 3, 4) contains fewer than three beds, if the stream (D, E, F, R) delimiting said zone and situated upstream of said zone is injected or withdrawn at the plate P.sub.i via the bypass line L.sub.i/i+1, then the stream delimiting said zone and situated downstream of said zone is injected/withdrawn at the plate P.sub.j via the bypass line L.sub.j/j+1, and if the stream delimiting said zone and situated downstream of said zone is injected or withdrawn at the plate P.sub.i via the bypass line L.sub.i−1/i, then the stream delimiting said zone and situated upstream of said zone is injected/withdrawn at the plate P.sub.j via the bypass line L.sub.j−1/j.

An efficient simulated moving bed device and an efficient simulated moving bed process are provided. The efficient simulated moving bed device comprises an adsorption bed, a raw material feeding system, a desorbent feeding system, a circulating system, an extract system, a raffinate system, a program-controlled valve group, and an automatic control system.