This present disclosure relates to processes and apparatuses for toluene methylation in an aromatics complex for producing paraxylene. More specifically, the present disclosure relates to processes and apparatuses for toluene methylation within an aromatics complex for producing paraxylene wherein an embodiment uses a riser reactor, another embodiment uses a pre-reactor producing dimethyl ether, and another embodiment uses partial regeneration of the catalyst.
The xylene isomers are produced in large volumes from petroleum as feedstocks for a variety of important industrial chemicals. The most important of the xylene isomers is paraxylene, the principal feedstock for polyester, which continues to enjoy a high growth rate from large base demand. Ortho-xylene is used to produce phthalic anhydride, which supplies high-volume but relatively mature markets. Meta-xylene is used in lesser but growing volumes for such products as plasticizers, azo dyes and wood preservers. Ethylbenzene generally is present in xylene mixtures and is occasionally recovered for styrene production, but is usually considered a less-desirable component of C8 aromatics.
Among the aromatic hydrocarbons, the overall importance of xylenes rivals that of benzene as a feedstock for industrial chemicals. Xylenes and benzene are produced from petroleum by reforming naphtha but not in sufficient volume to meet demand, thus conversion of other hydrocarbons is necessary to increase the yield of xylenes and benzene. Often toluene is de-alkylated to produce benzene or selectively disproportionated or transalkylated to yield benzene and C8 aromatics from which the individual xylene isomers are recovered.
An aromatics complex flow scheme has been disclosed by Meyers in the H
Traditional aromatics complexes send toluene to a transalkylation zone to generate desirable xylene isomers via transalkylation of the toluene with A9+ components. A9+ components are present in both the reformate bottoms and the transalkylation effluent.
Paraxylene is most often produced from a feedstock which has a methyl to phenyl ratio of less than 2. As a result, the paraxylene production is limited by the available methyl groups in the feed. In addition, paraxylene production also typically produces benzene as a byproduct. Since paraxylene is more valuable than benzene and the other byproducts produced in an aromatics complex, there is a desire to maximize the paraxylene production from a given amount of feed. There are also cases where a paraxylene producer would prefer to avoid the production of benzene as a byproduct or paraxylene production. However, there are also cases where a paraxylene producer would prefer to limit the production of benzene as a byproduct of paraxylene production by making adjustments.
The present subject matter relates to processes and apparatuses for toluene methylation in an aromatics complex for producing paraxylene. More specifically, the present disclosure relates to processes and apparatuses for toluene methylation in an aromatics complex for producing paraxylene. More specifically, the present disclosure relates to processes and apparatuses for toluene methylation within an aromatics complex for producing paraxylene wherein an embodiment uses a riser reactor, another embodiment uses a pre-reactor producing dimethyl ether, and another embodiment uses partial regeneration of the catalyst.
Additional objects, advantages and novel features of the examples will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description and the accompanying drawings or may be learned by production or operation of the examples. The objects and advantages of the concepts may be realized and attained by means of the methodologies, instrumentalities and combinations particularly pointed out in the appended claims.
As used herein, the term “stream”, “feed”, “product”, “part” or “portion” can include various hydrocarbon molecules, such as straight-chain, branched, or cyclic alkanes, alkenes, alkadienes, and alkynes, and optionally other substances, such as gases, e.g., hydrogen, or impurities, such as heavy metals, and sulfur and nitrogen compounds. Each of the above may also include aromatic and non-aromatic hydrocarbons.
Hydrocarbon molecules may be abbreviated C1, C2, C3, Cn where “n” represents the number of carbon atoms in the one or more hydrocarbon molecules or the abbreviation may be used as an adjective for, e.g., non-aromatics or compounds. Similarly, aromatic compounds may be abbreviated A6, A7, A8, An where “n” represents the number of carbon atoms in the one or more aromatic molecules. Furthermore, a superscript “+” or “−” may be used with an abbreviated one or more hydrocarbons notation, e.g., C3+ or C3−, which is inclusive of the abbreviated one or more hydrocarbons. As an example, the abbreviation “C3+” means one or more hydrocarbon molecules of three or more carbon atoms.
As used herein, the term “zone” can refer to an area including one or more equipment items and/or one or more sub-zones. Equipment items can include, but are not limited to, one or more reactors or reactor vessels, separation vessels, distillation towers, heaters, exchangers, pipes, pumps, compressors, and controllers. Additionally, an equipment item, such as a reactor, dryer, or vessel, can further include one or more zones or sub-zones.
As used herein, the term “rich” can mean an amount of at least generally 50%, and preferably 70%, by mole, of a compound or class of compounds in a stream.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure.
The following description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of exemplary aspects. The scope of the present disclosure should be determined with reference to the claims.
In an embodiment, the system 10 further includes passing the alkylate aromatic product 110 to a light olefins column to produce a light olefins product stream. Then the light olefins product stream may be passed to a toluene column to produce a toluene column product stream comprising paraxylene. In another embodiment the process 10 may include passing the light olefins product stream to a toluene column to produce a toluene column product stream comprising unreacted toluene and to recycle unreacted toluene to the reactor. The catalyst may include a MFI zeolite with silica-to-alumina ratio higher than 20, preferentially higher than 100, a silica or an alumina binder, or combined aluminosilicate binder; and a clay binder. In one embodiment, phosphorus is added to the catalyst. The MFI zeolite content in the catalyst is in the range of about 25 wt % to about 65 wt %. The catalyst may be in a powder format with an average particle size of about 70 microns to about 80 microns.
The pre-reactor operates at about 400° C. to about 500° C. The pre-reactor comprises an operating bed density of about 0.30 kg/m3 to about 0.80 kg/m3. In some embodiments, the residence time in the riser reactor is 4 seconds. The weight hourly space velocity of the riser reactor is about 4 to about 20. The weight hourly space velocity of the riser reactor is about 10 hr-1. The riser reactor system comprises a temperature of about 500° C. to about 700° C. The riser reactor system comprises an operating bed density of about 0.05 kg/m3 to 0.29 kg/m3.
The pre-reactor may include a plurality of injection zones. The riser reactor may also include a plurality of injection zones, as illustrated in the example in
In an embodiment, the system 200 further includes passing the alkylate aromatic product 260 to a light olefins column 270 to produce a light olefins product stream 280. Then the light olefins product stream 280 may be passed to a toluene column 290 to produce a toluene column product stream 300 comprising paraxylene. In another embodiment the process 200 may include passing the light olefins product stream 270 to a toluene column 290 to produce a toluene column product stream comprising unreacted toluene 310 and to recycle unreacted toluene 310 to the reactor 250. The catalyst may include a MFI zeolite with silica-to-alumina ratio higher than 20, preferentially higher than 100; a silica or an alumina binder, or combined aluminosilicate binder; and a clay binder. In one embodiment, phosphorus is added to the catalyst. The MFI zeolite content in the catalyst is in the range of about 25 wt % to about 65 wt %. The catalyst may be in a powder format with an average particle size of about 70 microns to about 80 microns.
In an embodiment, the regenerator 450 produces a product stream of catalyst 460 wherein about 0.1% to about 15% of coke is left on the catalyst and the partially regenerated catalyst 460 is returned to the riser reactor 320. In a preferred embodiment, the regenerator 450 produces a product stream of catalyst 460 wherein about 2% to about 4% of coke is left on the catalyst and the partially regenerated catalyst 460 is returned to the riser reactor 320. In one embodiment, the regenerator 450 is a bubbling bed regenerator. In another embodiment, the regenerator 450 is a swing bed regenerator. In another embodiment, the regenerator 450 is a fixed bed regenerator. The oxygen concentration may be about 0.5% to about 21.0%.
In an embodiment, the system 300 further includes passing the alkylate aromatic product 410 to a light olefins column to produce a light olefins product stream. Then the light olefins product stream may be passed to a toluene column to produce a toluene column product stream comprising paraxylene. In another embodiment the process 300 may include passing the light olefins product stream to a toluene column to produce a toluene column product stream comprising unreacted toluene and to recycle unreacted toluene to the reactor. The catalyst may include a WI zeolite with silica-to-alumina ratio higher than 20, preferentially higher than 100; a silica or an alumina binder, or combined aluminosilicate binder; and a clay. In one embodiment, phosphorus is added to the catalyst. The MFI zeolite content in the catalyst is in the range of about 25 wt % to about 65 wt %. The catalyst may be in a powder format with an average particle size of about 70 microns to about 80 microns.
The following examples are intended to further illustrate the subject embodiments. These illustrations of different embodiments are not meant to limit the claims to the particular details of these examples.
It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present subject matter and without diminishing its attendant advantages.
While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.
A first embodiment of the invention is a process for alkylating an aromatic hydrocarbon reactant with an alkylating reagent comprising methanol to produce an alkylated aromatic product, comprising passing water and toluene to a riser reactor system having a catalyst, for producing the alkylated aromatic product; recovering the alkylate aromatic product, produced by reaction of the aromatic reactant and the alkylating reagent, from the reactor system; wherein the riser reactor system comprises an operating bed density of about 0.05 kg/m3 to 0.29 kg/m3; and passing a portion of the catalyst to a regenerator. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the aromatic hydrocarbon reactant includes toluene, the alkylating reagent includes methanol, and the alkylated aromatic product includes xylene. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the regenerator produces a product stream of catalyst wherein about 0.1% to about 15% of coke is left on the catalyst and the partially regenerated catalyst is returned to the riser reactor. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the regenerator produces a product stream of catalyst wherein about 2% to about 4% of coke is left on the catalyst and the partially regenerated catalyst is returned to the riser reactor. The process of claim 1, wherein the regenerator is a bubbling bed regenerator. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the regenerator is a swing bed regenerator. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the regenerator is a fixed bed regenerator. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the oxygen concentration is about 0.5% to about 21.0% An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the residence time in the riser reactor is about 0.5 seconds to about 6 seconds. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the residence time in the riser reactor is 4 seconds. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the weight hourly space velocity of the riser reactor is about 4 to about 20 hr-1. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the weight hourly space velocity of the riser reactor is about 10 hr-1. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the riser reactor system comprises a temperature of about 500° C. to about 700° C. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the reactor system contains a catalyst comprising a MFI zeolite with silica-to-alumina ratio of about 20 to about 1200, a silica-alumina binder, a clay, and phosphorous with an MFI zeolite content in the range of about 25 wt % to about 65 wt %. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the riser reactor comprises a plurality of injection zones. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the riser reactor comprises about 1 to about 4 injection points. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the riser reactor comprises 2 injection points. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising passing the alkylate aromatic product to a light olefins column to produce a light olefins product stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising passing the light olefins product stream to a toluene column to produce a toluene column product stream comprising paraxylene. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising passing the light olefins product stream to a toluene column to produce a toluene column product stream comprising unreacted toluene and to recycle unreacted toluene to the reactor.
Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of this invention, without departing from the spirit and scope thereof, to make various changes and modifications of the invention and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.
In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.
This application claims priority from Provisional Application No. 62/437,013 filed Dec. 20, 2016, the contents of which cited application are hereby incorporated by reference in its entirety.
Number | Date | Country | |
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62437013 | Dec 2016 | US |