Process and apparatus for the methylation of toluene and benzene in an aromatics complex

Abstract

The present disclosure relates to methods and apparatus for methylating toluene and benzene in an aromatics complex for producing para-xylene. More specifically, the present disclosure relates to methods and apparatus for methylating toluene and benzene in an aromatics complex for producing para-xylene, wherein one embodiment utilizes a reactor having a refractory material, including a low iron content refractory material.

Description

[0001] This application is a divisional application of the Chinese invention patent application entitled “Method and apparatus for methylating toluene and benzene in an aromatics complex”, filed on June 22, 2019, with application number 201980039222.5 and international application number PCT / US2019 / 038613. Technical Field

[0002] The present disclosure relates to methods and apparatus for methylating toluene and benzene in an aromatics complex for producing para-xylene. More specifically, the present disclosure relates to methods and apparatus for methylating toluene and benzene in an aromatics complex for producing para-xylene, wherein one embodiment utilizes a reactor having a refractory material, the refractory material including a low-iron refractory material. Background Art

[0003] Xylene isomers are produced in large quantities from petroleum as raw materials for use in a variety of important chemicals. The most important xylene isomer is p-xylene, the main raw material for polyester, which continues to enjoy high growth rates due to large-scale basic demand. Ortho-xylene is used to produce phthalic anhydride, which supplies a large but relatively mature market. Meta-xylene is used less frequently, but its use in products such as plasticizers, azo dyes and wood preservatives is increasing. Ethylbenzene is commonly present in xylene mixtures and is sometimes recycled for styrene production, but it is generally considered to be a less desirable component of C8 aromatics.

[0004] Among aromatic hydrocarbons, xylenes rival benzene in overall importance as an industrial chemical feedstock. While xylenes and benzene are produced from petroleum through naphtha reforming, they are not produced in sufficient quantities to meet demand, necessitating conversion of other hydrocarbons to increase their yields. Typically, toluene is dealkylated to produce benzene, or selectively disproportionated or transalkylated to produce benzene, from which individual xylene isomers are recovered as C8 aromatics.

[0005] Meyers disclosed an aromatics complex flow scheme in Handbook of Petroleum Refining Processes, Second Edition, published by McGraw-Hill in 1997 and incorporated herein by reference.

[0006] Conventional aromatics complexes send toluene to the transalkylation zone to be converted to toluene via A 9+ The components transalkylate toluene to produce the desired xylene isomers. 9+ The components are present in the reformate bottoms and the transalkylation effluent.

[0007] Para-xylene is most commonly produced from feedstocks having a methyl to phenyl ratio of less than 2. Therefore, the production of para-xylene is limited by the available methyl groups in the feed. In addition, para-xylene production also typically produces benzene as a by-product. Since para-xylene is more valuable than other by-products produced in benzene and aromatics complexes, it is desirable to maximize para-xylene production from a given amount of feed.

[0008] The toluene methylation or benzylation process uses iron or iron-based alloys as the reactor material. Iron catalyzes hydrocarbons to form filamentous carbon, which can clog the reactor. Furthermore, in the presence of hydrocarbons, iron can corrode through a process known as metal dusting. Coke formation and metal dusting reduce reactor life and increase process operating costs. Shock can be minimized by lowering the process temperature, but this also reduces catalyst activity. For fluidized beds, a refractory layer is typically applied to the vessel interior to protect the metal walls from wear. The refractory typically contains a certain amount of iron. When exposed to methanol at 600°C, iron can also form metal-catalyzed coke and pulverize the refractory into small particles. In other cases, if coking is extreme, the refractory can peel from the walls and fall into the reactor, damaging the interior. This is known as "jacketing." In this case, the refractory is no longer effective and can damage other reactor components. Summary of the Invention

[0009] The present invention relates to a method and apparatus for methylating toluene in an aromatics complex for producing paraxylene. More specifically, the present disclosure relates to a method and apparatus for methylating toluene in an aromatics complex for producing paraxylene, wherein a special refractory layer has been applied to the inner wall of the reactor. The present invention proposes applying a specific refractory layer on the inner wall of the reactor. The refractory material has a low iron content (less than 0.1% by weight); therefore, the formation of coke can be significantly reduced. In addition, the refractory layer can act as a thermal barrier to allow the metal walls to be maintained at a temperature below the process temperature, thereby further reducing coke formation on the walls. This refractory layer can be applied to both fixed bed reactors and fluidized bed reactors.

[0010] 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 or may be learned by production or operation of the examples. The objects and advantages of the concepts may be realized and obtained by the methods, instrumentalities and combinations particularly pointed out in the appended claims.

[0011] definition

[0012] As used herein, the terms "stream," "feed," "product," "component," or "portion" may include various hydrocarbon molecules such as linear, branched, or cyclic alkanes, alkenes, alkadienes, and alkynes, and optionally other species such as gases, for example, hydrogen, or impurities such as heavy metals, and sulfur and nitrogen compounds. Each of the above may also include aromatic and non-aromatic hydrocarbons.

[0013] Hydrocarbon molecules may be abbreviated as C1, C2, C3, Cn, where "n" represents the number of carbon atoms in one or more hydrocarbon molecules, or the abbreviation may be used as an adjective, for example, for a non-aromatic compound or compound. Similarly, aromatic compounds may be abbreviated as A6, A7, A8, An, where "n" represents the number of carbon atoms in one or more aromatic hydrocarbon molecules. In addition, the subscript "+" or "-" may be used to abbreviate one or more hydrocarbon symbols, for example, C 3+ or C 3- , which includes one or more hydrocarbons abbreviated. As an example, the abbreviation "C 3+ ” means one or more hydrocarbon molecules having three or more carbon atoms.

[0014] As used herein, the term "zone" may refer to an area that includes one or more equipment items and / or one or more subzones. Equipment items may include, but are not limited to, one or more reactors or reactor vessels, separation vessels, distillation columns, heaters, exchangers, piping, pumps, compressors, and controllers. Additionally, equipment items such as reactors, dryers, or vessels may also include one or more zones or subzones. DETAILED DESCRIPTION

[0015] The following description is not to be taken in a limiting sense but is merely for the purpose of describing the general principles of exemplary aspects. Reference should be made to the claims to determine the scope of the present disclosure.

[0016] The claimed invention includes a first embodiment in which a toluene methylation process or apparatus for alkylating an aromatic hydrocarbon reactant with an alkylating agent comprising methanol to produce an alkylated aromatic product comprises a reactor having a refractory material. The refractory material is located within the interior of the toluene methylation reactor. The present invention provides for applying a specific refractory material layer to the interior wall of the reactor. The refractory material has a low iron content (less than 0.1 wt %); thus, coke formation can be significantly reduced. In addition, the refractory material layer can act as a thermal barrier, allowing the metal wall to be maintained at a temperature below the process temperature, thereby further reducing coke formation on the wall. This refractory material layer can be applied to both fixed bed reactors and fluidized bed reactors. The reactor comprises a temperature range of 500°C to 700°C. The reactor has an operating bed density of 0.05 kg / m3 to 0.29 kg / m3. The reactor has a weight hourly space velocity of 4 hr-1 to 20 hr-1. The reactor can operate at a pressure of 1 barg to 10 barg. The mixed oxide can be applied to a retaining structure attached to the interior wall of the reactor. Afterwards, the mixed oxide undergoes a drying and calcination process to become hard and wear-resistant.

[0017] 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, and that such changes and modifications may be implemented without departing from the spirit and scope of the present invention and without diminishing its attendant advantages.

[0018] Specific implementation plan

[0019] While the following is described in conjunction with specific embodiments, it should be understood that this description is intended to illustrate and not to limit the scope of the foregoing description and the appended claims.

[0020] A first embodiment of the present invention is a method for alkylating an aromatic hydrocarbon reactant with an alkylating agent comprising methanol to produce an alkylated aromatic product, the method comprising: introducing the aromatic hydrocarbon into a reactor having a refractory lining, the refractory lining having a low iron content; and recovering the alkylated aromatic product produced by the reaction of the aromatic reactant and the alkylating agent from the reactor. An embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the aromatic hydrocarbon reactant comprises toluene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes. An embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the aromatic hydrocarbon reactant comprises benzene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes. An embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the reactor operates at a temperature of 500°C to 700°C. One embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the reactor operates at a pressure of 1 barg to 10 barg. One embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the entire inner lining of the reactor is coated with a refractory material. One embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the refractory material has a low iron content of between 0.0001 wt% and 0.5 wt%. One embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the refractory material has a low iron content of between 0.0001 wt% and 0.15 wt%. One embodiment of the present invention is one, any one, or all of the first embodiment of this paragraph through the previous embodiments of this paragraph, wherein the method further comprises adding water to the reactor.

[0021] A second embodiment of the present invention is an apparatus for alkylating an aromatic hydrocarbon reactant with an alkylating agent comprising methanol to produce an alkylated aromatic product, the apparatus comprising: a pipeline in upstream communication with a reactor having a refractory lining, the pipeline comprising an aromatic hydrocarbon; and a pipeline in downstream communication with the reactor, the pipeline comprising the alkylated aromatic product produced from the reactor by the reaction of the aromatic reactant and the alkylating agent. One embodiment of the present invention is one, any, or all of the second embodiment of this paragraph through the preceding embodiments of this paragraph, wherein the aromatic hydrocarbon reactant comprises toluene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes. One embodiment of the present invention is one, any, or all of the second embodiment of this paragraph through the preceding embodiments of this paragraph, wherein the aromatic hydrocarbon reactant comprises benzene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes. One embodiment of the present invention is one, any, or all of the second embodiment of this paragraph through the preceding embodiments of this paragraph, wherein the aromatic hydrocarbon reactant comprises benzene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes. One embodiment of the present invention is one, any, or all of the second embodiment of this paragraph through the preceding embodiments of this paragraph, wherein the reactor operates at a temperature of 500°C to 700°C. One embodiment of the present invention is one, any one or all of the second embodiment of this paragraph to the previous embodiments of this paragraph, wherein the reactor operates at a pressure of 1 barg to 10 barg. One embodiment of the present invention is one, any one or all of the second embodiment of this paragraph to the previous embodiments of this paragraph, wherein the entire inner lining of the reactor is coated with a refractory material. One embodiment of the present invention is one, any one or all of the second embodiment of this paragraph to the previous embodiments of this paragraph, wherein the refractory material has a low iron content of between 0.0001 wt% and 0.5 wt% iron. One embodiment of the present invention is one, any one or all of the second embodiment of this paragraph to the previous embodiments of this paragraph, wherein the refractory material has a low iron content of between 0.0001 wt% and 0.15 wt%. One embodiment of the present invention is one, any one or all of the second embodiment of this paragraph to the previous embodiments of this paragraph, wherein the apparatus further comprises an additional line connected to the reactor upstream, the additional line comprising water.

[0022] Although not described in further detail, it is believed that those skilled in the art can utilize the present invention to its fullest extent by using the foregoing description and can easily ascertain the essential characteristics of the present invention without departing from the spirit and scope of the present invention to make various changes and modifications to the present invention and adapt it to various uses and conditions. Therefore, the foregoing preferred specific embodiments should be understood as merely illustrative and not to limit the remainder of the present disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. In the foregoing, all temperatures are shown in degrees Celsius, and all parts and percentages are by weight unless otherwise indicated.

Claims

1. A method for alkylating an aromatic hydrocarbon reactant using an alkylating agent comprising methanol to produce an alkylated aromatic product, the method comprising: introducing the aromatic hydrocarbon reactant and the alkylating agent into a reactor having a refractory lining to produce an alkylated aromatic product, the refractory lining having an iron content of 0.0001 wt% to 0.15 wt% iron; as well as The alkylated aromatic product is recovered from the reactor, and wherein the alkylated aromatic product comprises xylenes.

2. The process of claim 1, wherein the aromatic hydrocarbon reactant comprises toluene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes.

3. The process of claim 1, wherein the aromatic hydrocarbon reactant comprises benzene, the alkylating agent comprises methanol, and the alkylated aromatic product comprises xylenes.

4. The method of claim 1, wherein the reactor is operated at a temperature of 500°C to 700°C.

5. The process of claim 1, wherein the reactor is operated at a pressure of 1 barg to 10 barg.

6. The process according to any one of claims 1 to 5, wherein the entire inner lining of the reactor is coated with a refractory material.

7. The method of any one of claims 1 to 5, further comprising adding water to the reactor.

8. The method of claim 6, further comprising adding water to the reactor.

9. An apparatus for alkylating an aromatic hydrocarbon reactant with an alkylating agent comprising methanol to produce an alkylated aromatic product, the apparatus comprising: a pipeline in upstream communication with a reactor having a refractory lining, the pipeline comprising aromatic hydrocarbons, the refractory lining having an iron content of 0.0001 wt% to 0.15 wt% iron; as well as A line is in downstream communication with the reactor, the line containing the alkylated aromatic product produced from the reactor by the reaction of the aromatic reactant and the alkylating agent.