Exxonmobil Chemical Patents Inc.

Georgia Tech Research Corporation

Other

Exxonmobil Research and Engineering Company

Exxonmobil Chemicals Patents, Inc.

Dana Lynn Pilliod

John Roger Porter

Timothy Paul Bender

Gaurav Agrawal

Michael W Weber

Robert G Tinger

Michael Salciccioli

Katy Conley Randall

Eric Martin Harding

Anthony Go

John Di-Yi Ou

Jeevan Sahib Abichandani

Michel Molinier

Sankar Nair

John Joseph Monson

Catherine M Dorsi

Yoshiaki Kawajiri

Meha Rungta

Siwei Guo

Ke Zhang

Arnold Hee-Sur Choi

Jason Bentley

David Lawrence Stern

Bal K Kaul

Glenn Allen Heeter

David Sholl

Harold William Helmke

Jason Gee

Chong Jhoo Wang

Para-xylene is separated from a mixture of xylenes and ethylbenzene by a separation process. An ortho-selective adsorbent is used to reduce the ortho-xylene concentration of the xylenes, prior to contact of the xylenes and ethylbenzene with a para-selective adsorbent. The stream rich in ortho-xylene may be isomerized in the liquid phase to increase the amount of para-xylene therein. The para-xylene-depleted stream may be treated in the vapor phase to remove the ethylbenzene and then subjected to isomerization in the liquid phase to produce a stream having a higher than equilibrium amount of para-xylene.

Process for recovering para-xylene

The process involves the use of two rotary valves to implement Varicol operation of a simulated moving bed apparatus to separate a product from at least one multicomponent feed. In a particular embodiment, paraxylene is separated from a mixture of C8 aromatic hydrocarbons. The use of the Varicol process further enhances the separation of the desired product and provides flexibility with a simulated moving bed apparatus using dual rotary valves.

Simulated moving bed separation process

A process to separate paraxylene from a mixture of paraxylene, metaxylene, orthoxylene, and ethylbenzene in a commercial simulated moving bed apparatus in a reduced number of beds is provided, allowing an additional separation to be conducted in the remaining beds. This additional separation may separate another xylene isomer, ethylbenzene, or a non-aromatic Chydrocarbon from the raffinate stream produced by the first separation. A PowerFeed process is used to recover paraxylene in a first adsorption zone containing 8-16 beds of a conventional 24-bed simulated moving bed adsorption apparatus, and then a second separation may be conducted in a second adsorption zone containing the remaining beds.

Xylene separation process

Para-xylene is separated from a mixture of C8 aromatics using a simulated moving bed (SMB) adsorption process, wherein a MOF is used as an adsorbent and an alkane or alkene having 7 or less carbon atoms, such as hexane or heptane is used as desorbent. Because of the difference in boiling points of a hexane or heptane desorbent as compared to conventional desorbents such as toluene or para-diethylbenzene, less energy is required to separate hexane or heptane from C8 aromatics by distillation than the energy required to separate toluene or diethylbenzene from C8 aromatics by distillation.

Process for recovering para-xylene using a metal organic framework adsorbent in a simulated moving-bed process

Disclosed is a process for recovering paraxylene in which a first simulated moving bed adsorption unit is used to produce two extract streams&#x2014;one rich in paraxylene and a paraxylene-rich extract stream that is lean in ethylbenzene and an ethylbenzene-rich extract stream that is lean in paraxylene- and a paraxylene-depleted raffinate stream. A significant amount of the ethylbenzene is removed in the ethylbenzene-rich extract stream (at least enough to limit buildup in the isomerization loop), so the paraxylene-depleted raffinate stream may be isomerized in the liquid phase. Avoiding vapor phase isomerization saves energy and capital, as liquid phase isomerization requires less energy and capital than the vapor phase isomerization process due to the requirement of vaporizing the paraxylene-depleted stream and the use of hydrogen, which requires an energy and capital intensive hydrogen recycle loop.

Processes for recovering paraxylene

Disclosed herein are processes for recovering paraxylene in which a first simulated moving bed adsorption unit is used to produce a paraxylene-rich extract stream that also contains a significant amount of the ethylbenzene and a paraxylene-depleted raffinate stream. Because a significant amount of the ethylbenzene is removed in the paraxylene-rich extract stream (at least enough to limit buildup in the isomerization loop), the paraxylene-depleted raffinate stream may be isomerized in the liquid phase. Avoiding vapor phase isomerization saves energy and capital, as liquid phase isomerization requires less energy and capital than the vapor phase isomerization process due to the requirement of vaporizing the paraxylene-depleted stream and the use of hydrogen, which requires an energy- and capital-intensive hydrogen recycle loop.

Process for the recovering of paraxylene

The present invention is an improved process and apparatus for producing para-xylene, particularly with respect to a process that involves the methylation of toluene and/or benzene to selectively produce para-xylene, wherein streams having differing amounts of ethylbenzene are separately treated in the recovery of para-xylene. A first hydrocarbon feed comprising xylenes and ethylbenzene is provided to a first para-xylene adsorption section, and a second hydrocarbon feed comprising xylenes and less EB than the first hydrocarbon feed is provided to a second para-xylene adsorption section. Segregating the feeds with differing ethylbenzene contents increases the overall efficiency of the adsorption of para-xylene by the adsorption units. Efficiency and energy savings may be further improved by subjecting the lower-content ethylbenzene stream to liquid phase isomerization.

Process and apparatus for the production of para-xylene

A process for producing para-xylene (PX) comprises supplying a hydrocarbon feed comprising xylenes and ethylbenzene (EB) to a PX recovery unit, where a PX-rich stream and at least one PX-depleted stream are recovered from the feed. The PX-depleted stream is then separated into an EB-rich stream and an EB-depleted stream in a divided wall column. The EB-depleted stream is then isomerized under at least partial liquid phase conditions to produce a first isomerized stream having a higher PX concentration than the PX-depleted stream, and the EB-rich stream is isomerized under at least partial vapor phase conditions to produce a second isomerized stream having a higher PX concentration than the PX-depleted stream. The first and second isomerized streams are then recycled to the PX recovery unit to recover additional PX and the process is repeated to define a so-called xylene isomerization loop.

A simulated moving bed process using dual, parallel rotary valves configured or plumbed to be operated independently in which the step times of the rotary valves are staggered. In embodiments, the second rotary valve is programmed to step about halfway through the step time of the first rotary valve. Staggering the step time of the parallel rotary valves, rather than utilizing simultaneous stepping, results in increased net composite paraxylene concentration of the extract stream, allowing for increased capacity of the simulated moving bed process and/or reduced energy consumption.

Xylene separation process and apparatus

A process for producing paraxylene is provided. The process includes separating a first mixture of Caromatic hydrocarbons in a simulated moving bed apparatus using a desorbent to produce (i) an extract comprising &#x2267;50.0 wt % of the paraxylene in the first mixture; (ii) a desorbent-rich raffinate comprising &#x2267;75 wt % of the desorbent withdrawn, and (iii) an desorbent-lean raffinate comprising &#x2266;25 wt % of the desorbent withdrawn in the desorbent-rich and desorbent-lean raffinates. The desorbent-lean raffinate can then, without an intervening separation step, be passed to a refinery process or a vapor phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-lean raffinate. The desorbent-rich raffinate can be passed to a liquid phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-rich raffinate.

Paraxylene separation process

The invention is directed to a process of contacting at least one zeolite, selected from the MWW family of zeolites, with an aromatic hydrocarbon stream in a system comprising at least one reactor containing the at least one zeolite, wherein the conditions in the reactor are adjusted in response to at least one measurement of the system so as to preferentially increase oxygenate removal or to preferentially increase olefin removal.

Treatment of aromatic hydrocarbon stream

A process for separating a product from a multicomponent feedstream to an adsorption apparatus or system is described. The apparatus or system may comprise a moving-bed or a simulated moving-bed adsorption means. The product comprises at least one organic compound, such as an aryl compound with alkyl substitutes. In embodiments the conduits used to supply the feedstream to the apparatus or system are flushed with media of multiple grades. The improvement is more efficient use of the desorbent. In embodiments the process achieves improvements in one or more of efficiency of adsorption separation, capacity of adsorption apparatus systems, and purity of product attainable by adsorption process.

Growing community of inventors

League City, TX, United States of America

Dana Lynn Pilliod