# US 2014/0155673 A1 · Process and device for simulated-countercurrent chromatographic separation for the production of metaxylene with high yield > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0155673 A1 - Document ID: US20140155673A1 - Status: Published application - Kind: A1 - Application number: 14/095,404 - Filed: 2013-12-03 - Published: 2014-06-05 - Earliest claimed: 2012-12-03 - Assignees: Ifp Energies Nouvelles - Applicants: IFP Energies nouvelles - Inventors: Pascal ETIENNE; Philibert LEFLAIVE; Damien LEINEKUGEL LE COCQ; Catherine LAROCHE - Web page: https://patentgrep.com/patent/US20140155673A1 ## CPC - C07C 7/13: by molecular-sieve technique - B01D 15/1828: {characterised by process features} - B01D 15/1842: {characterised by apparatus features} - B01J 20/186: {Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity} - B01J 20/28011: {Other properties, e.g. density, crush strength} - B01J 20/2803: {Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products} - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS ## Abstract This invention describes a process for separation of xylenes for the purpose of the production of high-purity metaxylene, a simulated countercurrent process using at least one adsorber with a limited cumulative total level (Hcu) of adsorbent at a surface velocity (Vsl) that is less than 2 cm/s. ## Claims ### Claim 1 Process for separation of metaxylene by simulated countercurrent chromatography (CCS) starting from a feedstock F that essentially comprises metaxylene and its C8 aromatic isomers, using a zeolitic adsorbent solid based on Y zeolite crystals and a non-zeolitic phase, in which the Y zeolite crystals have a mean diameter of a number that is less than or equal to 1.7 μm, preferably less than or equal to 1.5 μm, and preferably also less than or equal to 1.2 μm, a process that uses at least one adsorber that is divided into 4 chromatographic zones that are defined in the following manner: Zone 1: Zone for desorption of metaxylene, encompassed between the injection of the desorbent D and the sampling of the extract E, Zone 2: Zone for desorption of isomers of metaxylene, encompassed between the sampling of the extract E and the injection of the feedstock that is to be fractionated F, Zone 3: Zone for adsorption of metaxylene, encompassed between the injection of the feedstock and the draw-off of the raffinate R, Zone 4: Zone located between the draw-off of raffinate R and the injection of the desorbent D, with the number of beds of each adsorber being between 6 and 18 beds, and preferably between 8 and 15 beds, with the beds all being identical, and the height of each bed being between 0.7 m and 1.40 m, said process being characterized in that it has a cumulative level (Hcu) of adsorbent solid on the different adsorber(s) of between 6 m and 21 m, and in that the mean surface velocity over each adsorber (Vsl) is between 0.9 cm/s and 1.8 cm/s, with said surface velocity being defined as the volumetric flow rate of mean recycling at the temperature of the process that is divided by the area of the cross-section of the adsorber and the cumulative height (Hcu) of adsorbent solid being distributed in the following manner: The cumulative level of adsorbent solid in zone 1, on average over a cycle, is 17%±5% of (Hcu), The cumulative level of adsorbent solid in zone 2, on average over a cycle, is 41.5%±5% of (Hcu), The cumulative level of adsorbent solid in zone 3, on average over a cycle, is 25%±5% of (Hcu), The cumulative level of adsorbent solid in zone 4, on average over a cycle, is 16.5%±5% of (Hcu). ### Claim 2 (depends on 1) Process for separation of xylenes according to claim 1, wherein the Si/Al atomic ratio of the adsorbent is preferably such that 2.0