# US 2014/0155672 A1 · Process and apparatus for simulated counter-current chromatographic separation for high-productivity production of paraxylene > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0155672 A1 - Document ID: US20140155672A1 - Status: Published application - Kind: A1 - Application number: 14/093,599 - Filed: 2013-12-02 - 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/US20140155672A1 ## CPC - 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 7/13: by molecular-sieve technique - 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 - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract The present invention describes a process for the separation of xylenes in simulated counter-current utilising at least one adsorber with a limited cumulated total height (Hcu) of adsorbent and a superficial velocity (Vsl) of less than 2 cm/s. ## Claims ### Claim 1 A process for separation of paraxylene by simulated counter-current (SCC) chromatography from a charge F essentially comprising paraxylene and its aromatic C8 isomers, utilising a zeolitic adsorbent solid based on zeolite crystals X and a non-zeolitic phase, in which the zeolite crystals X have an average diameter by number of between 0.1 and 1.5 microns and preferably between 0.1 and 1.2 microns, said process using at least one adsorber divided into 4 chromatographic zones defined in the following fashion: Zone 1: zone for desorption of the paraxylene, between injection of the desorbent D and withdrawal of the extract E. Zone 2: zone for desorption of the isomers of the paraxylene, between the withdrawal of the extract E and injection of the charge F to be fractionated. Zone 3: zone for adsorption of the paraxylene, between injection of the charge and withdrawal of the raffinate R. Zone 4: zone between withdrawal of the raffinate R and injection of the desorbent D, the number of adsorption beds being between 6 and 18 and preferably between 8 and 15 beds, the beds all being identical, and the height of each bed being between 0.7 m and 1.4 m, said process being characterised in that it has a cumulated height of adsorbent solid in relation to the different adsorber or adsorbers (Hcu) of between 6 m and 21 m and that the mean superficial velocity over each adsorber (Vsl) is between 1 cm/s and 2 cm/s, said superficial velocity being defined as the mean recycling flow rate by volume at the temperature of the process divided by the area of the section of the adsorber, and the cumulated height (Hcu) of adsorbent solid being distributed in the following fashion: the cumulated height of adsorbent solid in zone 1 on average over a cycle is 21%±5% of (Hcu), the cumulated height of adsorbent solid in zone 2 on average over a cycle is 37.5%±5% of (Hcu), the cumulated height of adsorbent solid in zone 3 on average over a cycle is 29%±5% of (Hcu), the cumulated height of adsorbent solid in zone 4 on average over a cycle is 12.5%±5% of (Hcu). ### Claim 2 (depends on 1) A process for the separation of xylenes according to claim 1 wherein the atomic ratio Si/Al of the adsorbent is such that 1.05