Abstract: An as prepared Na-ETS-10 zeolite was modified by ion exchange with a mono-, di-, or tri-valent cation and mixtures thereof. Several of the modified ETS-10 zeolites showed improved pressure swing capacity during the selective adsorption of ethylene from an ethylene/ethane mixture, relative to Na-ETS-1 0, although the selectivity of adsorption decreased. Modification with Ba2+ and Ba2+/H+ provided modified ETS-10 zeolite adsorbents having a good balance of selectivity and pressure swing capacity for the separation of ethylene/ethane mixtures, making them useful adsorbents for PSA processes.

Abstract: A method for reducing halide concentration in a hydrocarbon product having an organic halide content from 50 to 4000 ppm which is made by a hydrocarbon conversion process using an ionic liquid catalyst comprising a halogen-containing acidic ionic liquid comprising contacting at least a portion of the hydrocarbon product with at least one molecular sieve having pore size from 4 to 16 Angstrom under organic halide absorption conditions to reduce the halogen concentration in the hydrocarbon product to less than 40 ppm is disclosed.

Abstract: An apparatus and process are provided for thermally cracking hydrocarbon feeds containing paraffin insoluble compounds by selectively adsorbing paraffin-insoluble compounds with solid particulate adsorbents, prior to cracking. An aromatics-containing stream such as one derived from cracked product is used to desorb the paraffin insoluble compounds from the adsorber stage.

Abstract: The present invention is directed to an improved hydrocarbon adsorbent slurry washcoat formulation, which can be used for controlling evaporative hydrocarbon emissions from a motor vehicle. More specifically, the present invention is directed to an improved slurry composition of the present invention comprises one or more hydrocarbon adsorbent materials, and an organic polymer binder containing an anionic dispersant and/or stabilizing pH. The binder is used to improve the adhesion of the hydrocarbon adsorbent to the surface of the fuel storage, fuel delivery, or air intake system component.

Abstract: Preparation of polyisobutylene having a content of terminal double bonds of more than 50% by polymerizing isobutene using a polymerization catalyst customary therefor from a technical 1-butene-, 2-butene- and isobutene-containing C4 hydrocarbon stream which may comprise up to 3000 ppm by weight, of 1,3-butadiene, by reducing the content of oxygenates in the C4 hydrocarbon stream before the polymerization of the isobutene by contacting it with an inorganic adsorbent at a pressure of from 1 to 20 bar and a temperature of from 20 to 220° C.

Abstract: A desulfurization system is operated in a manner which optimizes sulfur removal and octane retention. When the desulfurization reactor is operated at a specific ratio of total pressure to hydrogen partial pressure (PT/PH) and/or within a specific temperature range, optimum sulfur removal and octane retention are realized. The desulfurization reactor can be maintained at these optimized operating conditions by automatically adjusting one or more operating parameters of the desulfurization reactor in order to maintain a substantially constant hydrogen partial pressure (PH) in the reactor. Maintaining a relatively constant hydrogen partial pressure (PH) in the desulfurization reactor helps ensure a relatively consistent degree of desulfurization.

Abstract: A method is disclosed for reducing levels of residual halogen and Group IIIb metals in a crude poly(?-olefin) polymerized in the presence of a catalyst comprising the halogen and Group IIIb metals, wherein the method comprises: A) washing the crude poly(?-olefin) with water; B) separating the aqueous and organic phases; C) then adding an adsorbent selected from the group consisting of magnesium silicates, calcium silicates, aluminum silicates, aluminum oxides, and clays to the organic phase to form a slurry; D) heating the slurry under reduced pressure at a temperature of at least about 180° C. for at least about thirty minutes; and then E) separating the adsorbent from the slurry.

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: A hydrocarbon sequestering product, a method to obtain the product, and a method and a facility to sequester hydrocarbons, wherein the product comprises an oleophilic filamentous material that gets in contact with a medium contaminated by one or more hydrocarbons with the purpose of sequestrating the hydrocarbon(s) present in the medium to free it from said hydrocarbons.

Abstract: A method for adsorbing volatile organic compounds (VOCs) derived from organic matter comprises adsorbing the VOCs onto palladium doped ZSM-5, optionally at ambient temperature. The organic matter can be perishable organic goods such as food, including fruit and/or vegetables, horticultural produce, including plants and/or cut flowers, or refuse. The palladium doped ZSM-5 has a Si:Al ratio of less than or equal to 100:1 and preferably has a palladium content of from 0.1 wt % to 10.0 wt % based on the total weight of the doped ZSM-5.

Abstract: The present invention is directed to an improved integrated process for the removal of heavy hydrocarbons, carbon dioxide, hydrogen sulfide, and water from a raw natural gas feed stream. More specifically, the integrated process of the present invention comprises a three step process involving the adsorption of heavy hydrocarbons and water on an adsorbent bed selective for the same, a subsequent aqueous lean amine treatment for the absorptive removal of acid gases, such as carbon dioxide and hydrogen sulfide, and an adsorptive removal of water. The process of the present invention results in a highly purified natural gas product stream.

Abstract: A method and product for removing sulfur compound molecules from gasoline or diesel fuel includes exposing the gasoline or diesel fuel to a plurality of molecularly imprinted polymer beads (MIPS) that have receptor sites on the surfaces thereof that include imprints that match the physical shape of at least a portion of a sulfur compound molecule. A quantity of the sulfur molecules align with and adhere to some of the receptor sites and, accordingly, they are removed from the gasoline or diesel fuel producing a remediated or sweetened gasoline or diesel fuel. According to one embodiment, the MIPS are contained in an enclosure having a plurality of openings large enough to permit the solution to pass through and small enough so as to prevent the MIPS from passing through. According to another embodiment the MIPS are applied (i.e., coated) to the inside surface of a conduit and the gasoline or diesel fuel is forced or allowed to flow through the conduit thereby removing some of the sulfur molecules therefrom.

Abstract: A non-homogeneous adsorbent is described, formed of a core and at least one continuous outer layer in which the core of said adsorbent has a volume adsorptive capacity representing at least 35% of the volume of the adsorbent and the outer layer has a diffusional selectivity greater than 5. The adsorbent is used in gas-separation processes or liquid-separation processes.

Abstract: A method for separating a mixture of hydrocarbons into fractions enriched in linear, mono-branched, or multi-branched hydrocarbons is disclosed. In particular, mono-branched alkanes are separated from a mixture of alkanes containing multi-branched, mono-branched and linear alkanes, by selectively adsorbing the mono-branched alkanes on a zeolitic adsorbent. The zeolitic adsorbent MCM-22 is particularly suitable for carrying out the method.

Abstract: Methods and apparatus for the purification and distribution of acetylene. Acetylene is removed from an acetylene storage device, and provided to a purifier where solvent is removed. The purified acetylene is then provided to a semiconductor processing tool.

Abstract: The present invention discloses a method of utilizing a catalytic reaction to recycle organic scrap, wherein via a special cracking equipment, a special catalyst and a two-stage cracking process, the present invention not only can effectively convert organic scrap into regenerated oil but also can promote the yield and quality of the regenerated oil; further, the method of the present invention can overcome environmental problems and has the characteristics of high safety, high stability, and high economic efficiency.

Abstract: It is now possible to purify diene-contaminated liquid and gas streams by treating these streams with adsorbents comprising single or multiple transition metal polycation-exchanged faujasites having silicon to aluminum ratio from 0.9 to about 9.0, wherein said transition metal (Tr) polycations have the general formula [Tr?O?]n+, wherein a varies from 2 to 8, ?—from 0 to 4, and n—from 1 to 3 and wherein said transition metals include IB. IIB, VIIB and VIII Group metals preferably selected from the group consisting of copper, cadmium, zinc, manganese, nickel and iron.

Abstract: Stable catalyst carrier impregnating solutions can be prepared using a component of a Group VIB metal, e.g., molybdenum, at high concentration, a component of a Group VIII metal, e.g., nickel, at low concentration, and a phosphorous component, e.g., phosphoric acid, at low concentration, provided that the Group VIII metal is in a substantially water-insoluble form and a particular sequence of addition of the components is followed, even when a substantially water-insoluble form of the Group VIB component is used. The resulting stabilized impregnating solution can be supplemented with additional Group VIII metal in water-soluble form to achieve increased levels of such metal in the final catalyst. Furthermore, uncalcined catalyst carriers impregnated with the stable solution and subsequently shaped, dried and calcined, have unexpectedly improved performance when used in the hydroprocessing of heavy hydrocarbon feedstocks.

Abstract: Disclosed is a simulated moving bed (SMB) adsorptive separation system in which at least one component of a fluid mixture is brought into contact with a solid adsorbent and the adsorbed component is desorbed with a desorbent, wherein the improvement comprises an inert ball layer is formed on the upper part of the solid absorbent filled in the simulated moving bed.

Abstract: A process for reducing the content of oxygen-containing and/or nitrogen-containing compounds in streams having an isobutene content of at least 10% by weight, which comprises passing the stream in the liquid state at a temperature T [in K] and a linear velocity v [in cm/min] over a fixed bed of an acid-free zeolite having a mean pore size of from 0.3 to 1.5 nm, where the fixed bed has a length l [in cm] in the flow direction of the stream and T, v and l obey the relationship 2(T?283 K)/10 K·l/v?500 min, is described. The process avoids the formation of isobutene oligomers.

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: 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: The present invention provides processes for removing CO2 from an effluent stream derived from an oxygenate to olefins reaction system. In one embodiment, the invention comprises contacting the effluent stream with a first CO2 removal medium in a first CO2 removal zone under conditions effective to remove a first portion of the CO2 from the effluent stream and form a first CO2 depleted stream. The first CO2 depleted stream is contacted with a second CO2 removal medium in a second CO2 removal zone under conditions effective to remove a second portion of the CO2 from the first CO2 depleted stream and form a second CO2 depleted stream comprising less than about 0.5 vppm CO2.

Abstract: Processes suitable for purifying aromatic-containing feed streams, and processes using such purified streams are described, wherein the purification processes comprise: (a) providing a process feedstream comprising an aromatic component; and (b) bringing the process feedstream into contact with a first zeolite and a second zeolite; wherein the first zeolite has a mean pore size of 0.3 to 0.5 nm, and wherein the second zeolite has a mean pore size of 0.6 to 0.8 nm.

Abstract: A method of adapting an axial flow reaction vessel having opposed ports to an opposed axial flow reaction vessel comprises installing a process fluid collection means system within the body of the vessel in fluid communication with one or more of said ports.

Abstract: The present invention relates to a novel process for refining the liquefied petroleum gas (LPG) in a commercial scale. The process comprises: sequentially performing fine desulfurization and mercaptan conversion of the LPG after alcohol amine treatment through desulfurizer and catalyst set in fixed bed reactor in the absence of alkali, wherein, during the fine desulfurization, the resultants of reaction between hydrogen sulfide in the LPG and Fe—Ca oxides or their hydrates adhered on the desulfurizer, and during the mercaptan conversion, the mercaptan in the LPG reacts with the residual trace amount of air in the LPG under the action of the catalyst to produce the disulfides; letting the formed disulfides along with the LPG flow out of the fixed bed reactor; rectifying the LPG after the mercaptan conversion to obtain the refined LPG products, with further rectification to obtain the valuable disulfide products.

Abstract: The present invention is related to a method for kinetically separating a light hydrocarbon mixture comprising at least two components by preferentially adsorbing a first component on a zeolite adsorbent comprising 8-member rings of tetrahedra as the pore opening controlling hydrocarbon diffusion and alkali metal cations balancing a framework charge, wherein a second component is not preferentially adsorbed. The novel process comprises contacting the light hydrocarbon mixture with a zeolite adsorbent having a SiO2/Al2O3 ratio greater than about 50 and less than 200 and further having a diffusion rate at least 50 times greater for the first component as compared to the second component, and then recovering at least one of the first component or the second component.

Abstract: Removing impurities from a heptane stream by contacting the heptane stream with an acidic catalyst, wherein the contacting reduces a concentration of one or more close boiling impurities, one or more olefins, or both. The impurities are isomerized via contact with the acidic catalyst into species that possess lower octane levels or that do not possess boiling points as near to the boiling point of n-heptane, which promotes separation of the impurities via distillation. Close boiling impurities may include such compounds as cis-1,2-dimethylcyclopentane and methylcyclohexane or may be compounds having boiling points at a standard pressure of 760 Torr in the range of about 96.5 to about 100.5 degrees Celsius including such compounds as cis-1,2-dimethylcyclopentane and methylcyclohexane. The concentration of cis-1,2-dimethylcyclopentane and methylcyclohexane may be reduced by at least about 25 and 10 percent by weight, respectively.

Abstract: This invention is to a process for removing dimethyl ether from an olefin stream. The process includes contacting the olefin stream with a molecular sieve that has improved capacity to adsorb the dimethyl ether from the olefin stream. The molecular sieve used to remove the dimethyl ether has low or no activity in converting the olefin in the olefin stream to other products.

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 method for improving performance of an engine comprising contacting contaminated liquid hydrocarbon fuel comprising an initial concentration of DRA with one or more effective DRA removal agent under conditions effective to produce decontaminated liquid hydrocarbon fuel comprising a reduced concentration of the DRA, and feeding the decontaminated liquid hydrocarbon fuel to the engine.

Abstract: The present application provides a method for removing drag reducer additive (“DRA”) from liquid hydrocarbon fuel. The method comprises: providing contaminated liquid hydrocarbon fuel comprising an initial concentration of DRA; contacting the contaminated liquid hydrocarbon fuel with a quantity of fresh attapulgus clay under conditions effective to produce decontaminated liquid hydrocarbon fuel comprising a reduced concentration of the DRA; said fresh attapulgus clay being effective to remove about 10% or more of a target DRA when 1 g of the fresh attapulgus clay is added in increments of from about 0.02 gram to about 0.1 gram, with agitation, to 100 ml. of contaminated liquid hydrocarbon fuel comprising from about 8 to about 9 ppm of the unsheared target DRA.

Abstract: The present invention provides new highly-efficient separation processes and systems for separating polymerization-grade ethylene and propylene from an initial effluent stream comprising ethane, ethylene, propylene, dimethyl ether, and one or more of propane, acetylene, methyl acetylene, propadiene, methane, hydrogen, carbon monoxide, carbon dioxide and C4+ components. In one embodiment, the initial effluent stream is provided from a methanol-to-olefin reaction system. It has been discovered that an efficient separation of these components is realized when DME is partially removed in a first separation step comprising methanol and water washing steps, followed by separation of the remaining components in additional separation steps.

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: The present invention provides new highly-efficient separation processes and systems for separating polymerization-grade ethylene and propylene from an initial effluent stream comprising ethane, ethylene, propylene, dimethyl ether, and one or more of propane, acetylene, methyl acetylene, propadiene, methane, hydrogen, carbon monoxide, carbon dioxide and C4+ components. In one embodiment, the initial effluent stream is provided from a methanol-to-olefin reaction system. It has been discovered that an efficient separation of these components is realized when DME is partially removed in a first separation step comprising methanol and water washing steps, followed by separation of the remaining components in additional separation steps.

Abstract: At lower temperatures an acidic molecular sieve adsorbent preferentially adsorbs water and basic organic nitrogen compounds over weakly basic organic nitrogen compounds such as nitrites. Elevated temperatures improve the capacity of acidic molecular sieve adsorbents to adsorb nitrites in the presence of water.

Abstract: In a process for selectively separating 1-butene from a C4 feed stream comprising at least 1-butene, cis-2-butene and trans-2-butene, the feed stream is passed through a first bed of an adsorbent comprising a crystalline microporous material to form a substantially trans-2-butene-free effluent stream. Then, the substantially trans-2-butene-free effluent stream is passed through a second bed of an adsorbent comprising a crystalline microporous material to form a substantially 1-butene-free effluent stream, whereby the 1-butene is separated from the feed stream. The adsorbed 1-butene is then typically desorbed from the second adsorbent bed either by lowering the pressure or raising the temperature of the bed.

Abstract: It is an object of the present invention to provide a non-conjugated cyclic diene and a non-conjugated cyclic diene composition which enable the production of a polymer based on non-conjugated cyclic diene which makes it possible to produce a (co)polymer at a high degree of polymerization activity, and a method of producing a polymer based on non-conjugated cyclic diene which makes it possible to produce a (co)polymer at a high degree of polymerization activity. A non-conjugated cyclic diene is used which meets at least one of the following requirements: (1) it contains a compound having a seven-membered cyclic triene hydrocarbon structure in a specific amount or less and (2) it contains a conjugated polyene compound having an eight-membered bicyclic hydrocarbon structure in a specific amount.

Abstract: A novel process effective for the removal of organic sulfur compounds, organic nitrogen compounds and light olefins from liquid hydrocarbons is disclosed. The process more specifically addresses the removal of these contaminants from aromatic compounds including benzene and toluene and from naphtha. The liquid hydrocarbons are contacted with a blend of at least one metal oxide and an acidic zeolite. Preferably, the metal oxide comprises nickel oxide and molybdenum oxide and the acidic zeolite is acidic stabilized zeolite Y. This blend has a significant capacity for adsorption of impurities and can be regenerated by oxidative treatment.

Abstract: Novel methods for synthesizing wholly un-supported, high-flow catalytic membranes consisting of 100% crystalline ZSM-22 crystals with no binder phase, having sufficient porosity to allow high Weight Hourly Space Velocities of feedstock to pass through without generating back pressure. The ZSM-22 membranes perform favorably to existing bulk ZSM-22 catalysts (e.g., via 1-butene conversion and selectivity). The method of membrane synthesis, based on Vapor Phase Transport, allows free-standing, binder-less membranes to be fabricated in varied geometries and sizes so that membranes can be tailor-made for particular geometries applications. The ZSM-22 precursor gel may be consolidated into a semi-cohesive body prior to vapor phase crystallization, for example, by uniaxial pressing. These crystalline membranes may be modified by ion exchange, pore ion exchange, framework exchange, synthesis modification techniques to incorporate other elements into the framework, such as K, H, Mg, Zn, V, Ga, and Pt.

Abstract: A process for making a selectively branched alcohol composition contacting a lower olefin feed comprising linear olefins having at least 3 carbon atoms and a concentration of phosphorous-containing compounds with a sorbent comprising a metal or metal oxide on a support, thereby substantially reducing the concentration of phosphorous-containing compounds and producing a purified lower olefin feed. The purified lower olefin feed is skeletally isomerized and then treated to selectively hydrogenate dienes before hydroformylation to produce selectively branched alcohols.

Abstract: The present invention is directed to the removal of nitrogen and sulfur containing impurities from high molecular weight petroleum feedstock obtained from fluid cracking catalyst or distillation zone of a petroleum treatment plant. The present process comprises first treating C12 and higher hydrocarbon petroleum feedstock having nitrogen and sulfur containing compounds therein with a porous, particulate adsorbent comprising a silica matrix having an effective amount of metal atoms therein to cause the adsorbent to have Lewis acidity of at least 500 ?mol/g and then treating the resultant feedstock to catalytic hydrodesulfurization to produce a hydrocarbon fuel having low sulfur and nitrogen content.

Abstract: A process for removing sulfur compounds from hydrocarbon streams by contacting the hydrocarbon stream, especially a gasoline stream, with an adsorbent material. The adsorbent material is regenerated with hydrogen or a hydrogen/H2S mixture.

Abstract: A process for producing a high RON naphtha which comprises contacting a hydrocarbon feed stream comprising a mixture of the isomers of C5 and C6 paraffins with a CFI zeolite, such as CIT-5, in an adsorption zone, whereby the branched isomers of the C5 and C6 paraffins are preferentially adsorbed by the CFI zeolite as compared to the straight chain isomers, and recovering a naphtha product from the adsorption zone having a higher RON than the hydrocarbon feed stream, also including a hydroisomerization process and a hydrocracking process.

Abstract: A process for producing a high RON naphtha which comprises contacting a hydrocarbon feed stream comprising a mixture of the isomers of C5 and C6 paraffins with ATS zeolite, such as SSZ-55, in an adsorption zone, whereby the branched isomers of the C5 and C6 paraffins are preferentially adsorbed by the ATS zeolite as compared to the straight chain isomers, and recovering a naphtha product from the adsorption zone having a higher RON than the hydrocarbon feed stream, also including a hydroisomerization process and a hydrocracking process.

Abstract: The application relates to a method for selecting drag reducer additive (DRA) effectively removable by activated carbons and graphites to be used in fuel. The appliction also relates to effective activated carbons and graphites for removing DRA from fuel, and to a method of using effective activated carbons and graphites to remove DRA from fuel.

Abstract: The present invention is a separation process for producing a methanol, ethanol and/or dimethyl ether stream from a first stream containing C3+ hydrocarbons. The first stream comprises C3+ hydrocarbons, methanol, ethanol and/or dimethyl ether. The process comprises the step of passing the first stream through an adsorbent bed having a crystalline microporous material that preferentially adsorbs methanol, ethanol and/or dimethyl ether over the C3+ hydrocarbons.

Abstract: Colloidal crystalline molecular sieve seeds are used in phosphorus-containing crystalline molecular sieve manufacture. Certain of the products have enhanced utility in oxygenate conversions.

Abstract: A process for treating organic compounds includes providing a composition which includes a substantially mesoporous structure of silica containing at least 97% by volume of pores having a pore size ranging from about 15 ? to about 30 ? and having a micropore volume of at least about 0.01 cc/g, wherein the mesoporous structure has incorporated therewith at least about 0.02% by weight of at least one catalytically and/or chemically active heteroatom selected from the group consisting of Al, Ti, V, Cr, Zn, Fe, Sn, Mo, Ga, Ni, Co, In, Zr, Mn, Cu, Mg, Pd, Pt and W, and the catalyst has an X-ray diffraction pattern with one peak at 0.3° to about 3.5° at 2?. The catalyst is contacted with an organic feed under reaction conditions wherein the treating process is selected from alkylation, acylation, oligomerization, selective oxidation, hydrotreating, isomerization, demetalation, catalytic dewaxing, hydroxylation, hydrogenation, ammoximation, isomerization, dehydrogenation, cracking and adsorption.

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.