Integrated process for producing phenol from coal-derived liquids

Abstract

A process for producing phenol, cresols, and xylenes from a coal-derived feedstock is described. The process combines dealkylation of alkylphenols from coal-derived liquids followed by benzene and / or toluene transalkylation to reduce non-ideal alkylbenzene production and reduce benzene / toluene usage. The alkylphenols from the coal-derived liquids are converted in a dealkylation reaction zone including a dealkylation reactor to produce phenol. Unconverted alkylphenols and aromatics such as benzene or toluene are fed to a transalkylation reaction zone including a transalkylation reactor to produce more phenol. Cresols and xylenes may also be produced.

Description

[Technical field]

[0001] The present invention relates to an integrated process for producing phenol from coal-derived liquids. [Background technology]

[0002] Coal-derived liquids from coal gasification and coking plants contain many valuable phenolic compounds, including phenol, cresols, and xylenols, as well as the less desirable long chain alkylphenols. For example, Junmin Zhang, Gong Liu, "Comprehensive Utilization of Low-temperature Coal Tar", Coal Conversion, 92~96, 33 (2010); Xiaojing Zhang, "Hydrogenation Process for Coal Tar from Mid-low-temperature Coal Carbonization", J. of China Coal Society, 840~844, 36 (2011); Shiyu Wang, Xiaoyan Bai, Yang Zhang, Libin Wang, Sijian Qu, "The Separation of Group Composition by Column Chromatography and GC / MS Analysis" Clean Coal Technology, 59~62, 16 (2010); Xianglan Li, Xintao Cui, Yongfa Zhang, "Analysis of Low Temperature Coal Tar in Inner Mongolia Lignite Briquette by GC-MS", Analytical Instrument, 17~25, 3(2012);Xuezhi Liu, Pang See Jin, "Study on the Tar Structure and Nature if Pressurized Pyrolysis for Tianzhu Coal in Gansu," Coal Conversion, 82-88, 17 (1994); and https: / / www.dakotagas.com / products / chemicals-and-fuels / dephenolized-cresylic-acid.Long chain alkylphenols have alkyl groups with 2 or more carbon atoms (eg, ethylphenol, propylphenol, butylphenol, methylethylphenol, etc.).

[0003]

[0002] Long chain alkylphenols can be converted to phenol and ethylene and / or propylene by dealkylation. The catalytic vapor phase hydrodealkylation of low temperature tar acid fractions (170°C-270°C) to low boiling phenols has been studied in a flow system at temperatures ranging from 480-650°C and over a wide range of space velocities over a chromia-alumina catalyst at atmospheric pressure. See KK Tiwari, SN Banerji, Asit Bhattacharjee, and RN Bhattacharya, "Catalytic Hydrodealkylation of Tar Acids," Applied Catalysis, 39-51, 45 (1988).

[0004]

[0003] As discussed in Danny Verboekend, Yuhe Liao, Wouter Schutyser, and Bert F. Sels, "Alkylphenols to phenol and olefins by zeolite catalysis: A pathway to valorize raw and fossilized lignocellulose", Green Chem., 2016(1), 18, 297-306; and Yuhe Liao, Ruyi Zhong, Ekaterina Makshina et al., "Propylphenol to Phenol and Propylene over Acidic Zeolites: Role of Shape Selectivity and Presence of Steam", ACS Catal. 2018, 8, 9, 7861-7878, the phenol yield of the liquid product ranges from 26.8 wt% to 55.2 wt% for various fractions at 600°C. However, the phenol in the feedstock itself contributes to the yield, resulting in inaccurate results. Therefore, it may be necessary to separate it in advance. Ethylphenol and propylphenol can be highly selectively converted to the related base chemicals phenol and the corresponding olefins. Using a ZSM-5 zeolite catalyst and water / steam co-feed, highly efficient and robust dealkylation (95% selectivity to phenol and propylene) is achieved.

[0005]

[0004] Shogo Kumagai, Masaki Asakawa, Tomohito Kameda, Yuko Saito, Atsushi Watanabe, Chuichi Watanabe, Norio Teramae, and Toshiaki Yoshioka, “Selective phenol recovery via simultaneous hydrogenation / dealkylation of isopropyl- and isopropenyl-phenols employing an H 2As described in “Generator combined with tandem micro-reactor GC / MS”, Scientific Reports, 11-12, 8 (2018), complete isopropylphenol conversion with phenol selectivity of over 99% was obtained using Y-zeolite at 350 °C.

[0006]

[0005] Long-chain alkylphenols may be transalkylated using aromatic solvents such as benzene / toluene to convert the long-chain alkyl groups (ethyl, propyl, butyl, etc.) to obtain phenol and alkylbenzene. Transalkylation of 4-propylphenol with benzene was investigated using HZSM-5 at 350 °C. The major products from benzene transalkylation were found to be n-propylbenzene (58 mol%) and cumene (28 mol%). Xiaoming Huang, Jasper M. Ludenhoff, Mike Dirks, Xianhong Ouyang, Michael D. Boot, and Emiel JM Hensen, "Selective Production of Biobased Phenol from Lignocellulose Derived Alkylmethoxyphenols," ACS Catalysis, 11184-11190, 8 (2018).

[0007]

[0006] Another study on the transalkylation of p-propylphenol with benzene over a zeolite catalyst at 400 °C and 11.6 MPa shows that the phenol yield can reach 22 mol% after 8 hours of operation. The main product of the transalkylation with benzene was alkylbenzene. Takuya Yoshikawa, Takahiro Umezawa, Yuta Nakasaka, and Takao Masuda, "Conversion of alkylphenol to phenol via transalkylation using zeolite catalysts," Catalysis Today, 110-114, 347 (2020). However, this is not favorable when the market has a higher demand for phenol than for alkylbenzene.

[0008]

[0007] US2020 / 0031741 describes a process for producing xylenes and phenols by transalkylation of coal-derived liquids with benzene and / or toluene. Phenol, xylenol, and cresol, and long-chain alkylphenols are previously separated from the coal tar in this process. However, since cresol is a more valuable product than phenol, it is not desirable to feed cresol to the transalkylation unit to produce phenol and xylenes. No details are provided on how to treat the long-chain alkylphenols.

[0009]

[0008] WO2020162877 describes another method for producing phenol and xylene from a phenol-containing feedstock. In this invention, all alkylphenols except phenol are transalkylated with benzene and / or toluene. For high-value cresol components, there are the same problems as in US2020 / 0031741. In addition, large amounts of benzene and / or toluene are required for transalkylation of long-chain alkylphenols, which produces large amounts of alkylbenzene products. The size of the downstream processing equipment is relatively large and not cost-effective.

[0010]

[0009] WO2020 / 162876 describes an integrated dealkylation and transalkylation process for producing cresols from phenol-containing feedstocks, but the desired product from this process is cresol. Although phenol and cresol are separated beforehand, for dealkylation, xylenol is sent together with other heavy alkylphenols, which creates the possibility of cracking of xylenol. Furthermore, the reactor for this process is large. In addition, some aromatic compounds may be produced during dealkylation, and their separation from alkylphenols is not addressed. Summary of the Invention [Problem to be solved by the invention]

[0011]

[0010] Thus, there remains a need for methods for converting long chain phenols from coal-derived feedstocks to higher value products, such as phenols. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of one embodiment of a method according to the present invention; [Diagram 2] 4 is a schematic diagram of another embodiment of the method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013]

[0013] New processes for producing phenol, cresols, and xylenes from coal-derived feedstocks have been developed that integrate the dealkylation of alkylphenols from coal-derived liquids with transalkylation using benzene and / or toluene. The alkylphenols from the coal-derived liquids are converted to phenol by dealkylation. The unconverted alkylphenols and aromatics such as benzene or toluene are transalkylated to produce more phenol. Cresols and xylenes may also be produced. These processes maximize the phenol product yield and reduce the alkylbenzene yield.

[0014] Initial work involving toluene transalkylation with model components 4-ethylphenol and 2,6-xylenol showed that alkylbenzenes (xylene, ethylbenzene, ethyltoluene, etc.) have higher selectivity than phenol when the toluene / alkylphenol molar ratio is 6:1. Process simulation shows that toluene transalkylation of alkylphenol compounds of acid fraction from Xinjiang Hami low / medium coal tar (coal from Xinjiang Hami, China) can produce about 56 wt% alkylbenzenes and 11.5 wt% phenol.

[0015] One concern with the stand-alone transalkylation process is that several low-value alkylbenzene compounds, such as ethyltoluene and n-propylbenzene, are produced from long-chain alkylphenols. These alkylbenzene products have low market demand. The process starting with the dealkylation reaction produces phenol as the main product from ethylphenol, propylphenol, and ethylmethylphenol without producing low-value alkylbenzenes. However, xylenol and trimethylphenol have very poor reactivity to the dealkylation reaction. By integrating transalkylation into the process as a second reaction, xylenol and trimethylphenol can react with toluene to produce phenol, cresol, and xylene. In this way, not only is the production of less desirable alkylbenzenes avoided, but the reactor size and toluene consumption for the transalkylation reaction are significantly reduced.

[0016] Additional testing has shown that the dealkylation of ethylphenol using HZSM-5 catalyst has higher phenol selectivity.

[0017] By combining benzene or toluene transalkylation with dealkylation, it is possible to maximize phenol production and minimize alkylbenzene products. Long chain alkylphenols (e.g., ethylphenol, propylphenol, butylphenol, etc.) are dealkylated to phenol and olefins. Short chain alkylphenols (e.g., with alkyl groups having one carbon atom, such as xylenol and trimethylphenol) are transalkylated to phenol and cresols, with alkylbenzenes as by-products.

[0017]

[0018] The method of the present invention combines dealkylation of long-chain alkylphenols from coal-derived liquids followed by benzene and / or toluene transalkylation to reduce the production of less desirable alkylbenzenes. The long-chain alkylphenols from the coal-derived liquids are converted in a dealkylation reaction zone comprising a dealkylation reactor to produce phenol. Unconverted alkylphenols and xylenols, as well as aromatic compounds such as benzene or toluene or mixtures thereof, are fed to a transalkylation reaction zone comprising a transalkylation reactor to produce more phenol. In some embodiments, toluene is chosen as the solvent due to benzene's higher toxicity. Unconverted toluene, benzene, and other aromatic compounds may be recycled back to the transalkylation reaction zone to reduce the make-up of toluene and / or benzene.

[0018]

[0019] The process of the present invention involves separating phenol and cresol from alkylphenols from the coal-derived liquids prior to dealkylation and transalkylation, which can prevent the cracking of phenol and cresol to less valuable products during the dealkylation step and can also reduce the size of downstream processes and equipment.

[0019]

[0020] In one embodiment, the method of the invention involves separating the xylenol from the alkylphenols from the coal-derived liquids prior to dealkylation and transalkylation, which can prevent the xylenol from cracking into less valuable products during the dealkylation step and can also reduce the size of downstream processes and equipment.

[0020]

[0021] One aspect of the present invention is a method for producing phenol from a coal-derived feedstock. In one embodiment, the method includes the steps of: providing an alkylphenol stream comprising alkylphenols having alkyl chains with 2 or more carbon atoms; dealkylating the alkylphenol stream in a first dealkylation reaction zone comprising a first dealkylation reactor under first dealkylation reaction conditions in the presence of a first dealkylation catalyst to produce a first dealkylated effluent stream comprising light hydrocarbons, alkylbenzenes, phenols, cresols, and unconverted alkylphenols; separating the first dealkylated effluent stream in a dealkylation separation zone into at least a phenol stream comprising phenol and a bottom stream comprising unconverted alkylphenols; transalkylating the bottom stream and a reaction stream comprising toluene or benzene or both in a first transalkylation reaction zone comprising a first transalkylation reactor under first transalkylation reaction conditions in the presence of a first transalkylation catalyst to produce a first transalkylated effluent stream comprising cresols, phenols, and alkylbenzenes; introducing the first transalkylated effluent stream into the dealkylation separation zone; and recovering the phenol stream.

[0021]

[0022] In some embodiments, separating the first dealkylated effluent stream in the dealkylation separation zone includes separating the first dealkylated effluent stream into a phenol stream, a bottoms stream, and at least one of a cresol stream comprising cresol, a light hydrocarbon stream comprising light hydrocarbons, and an alkylbenzene stream comprising alkylbenzene.

[0022]

[0023] In some embodiments, the method further comprises separating the cresol stream in a cresol separation zone into a mixed cresol stream comprising p-cresol and o-cresol, and an m-cresol stream comprising m-cresol; isomerizing the mixed cresol stream in a cresol isomerization reaction zone under cresol isomerization reaction conditions in the presence of a cresol isomerization catalyst to form a cresol isomerization effluent stream comprising a mixture of cresols; recycling the cresol isomerization effluent stream to the cresol separation zone; and recovering the m-cresol stream comprising m-cresol.

[0023]

[0024] In some embodiments, the method further includes separating the alkylbenzene stream in an alkylbenzene separation zone into at least a recycle stream comprising one or more of benzene and toluene, a heavy alkylbenzene stream comprising alkylbenzenes having alkyl chains having two or more carbon atoms, and a mixed xylenes stream comprising a mixture of xylenes and ethylbenzene; and recycling the recycle stream from the alkylbenzene separation zone to the first transalkylation reaction zone.

[0024]

[0025] In some embodiments, the method further comprises separating the mixed xylene stream in a xylene separation zone into a second xylene stream comprising ethylbenzene, o-xylene, and m-xylene, and a p-xylene stream comprising p-xylene; isomerizing the second xylene stream in a xylene isomerization reaction zone under xylene isomerization reaction conditions in the presence of a xylene isomerization catalyst to form a xylene isomerization effluent stream comprising a mixture of xylenes; recycling the xylene isomerization effluent stream to the xylene separation zone; and recovering the p-xylene stream.

[0025]

[0026] In some embodiments, the method further comprises the steps of dealkylating the heavy alkylbenzene stream in a second dealkylation reaction zone comprising a second dealkylation reactor under second dealkylation conditions in the presence of a second dealkylation catalyst to form a dealkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene, or both; or transalkylating the heavy alkylbenzene stream in a second transalkylation reaction zone comprising a second transalkylation reactor under second transalkylation conditions in the presence of a second transalkylation catalyst to form a transalkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene, or both; and optionally recycling the dealkylated heavy alkylbenzene effluent stream, the transalkylated heavy alkylbenzene effluent stream, or both, to the alkylbenzene separation zone.

[0026]

[0027] In some embodiments, the bottom stream from the dealkylation separation zone further comprises toluene or xylenol or both.

[0028] In some embodiments, providing an alkylphenol stream includes providing a coal-derived feed stream to a first separation zone; and separating the coal-derived feed stream in the first separation zone into an alkylphenol stream and at least one of a first phenol stream comprising phenol, and a first cresol stream comprising cresol.

[0027]

[0029] In some embodiments, separating the coal-derived feed stream comprises separating the coal-derived feed stream by one or more of extraction, absorption, extractive distillation, crystallization, or membrane separation.

[0028]

[0030] In some embodiments, the coal-derived feed stream comprises a low temperature coal tar stream, a medium temperature coal tar stream, a high temperature coal tar stream, a cresylic acid stream, or a portion of a crude phenol mixture.

[0029]

[0031] In some embodiments, providing an alkylphenol stream comprises providing a coal-derived feed stream to a first separation zone; and separating the coal-derived feed stream into a phenol, cresol, and other alkylphenol stream.

[0030]

[0032] In some embodiments, the first dealkylation reaction conditions are a temperature in the range of 50° C. to 700° C., a pressure in the range of 0 MPa(g) to 5 MPa(g), and a reaction time of 0.1 to 300 h. -1 The range includes one or more of the WHSVs.

[0031]

[0033] In some embodiments, the first transalkylation reaction conditions include a temperature in the range of 50° C. to 600° C., a pressure in the range of 0 MPa(g) to 15 MPa(g), and a reaction time of 0.1 to 300 h. -1 The range includes one or more of the WHSVs.

[0032]

[0034] In some embodiments, the step of dealkylating the alkylphenol stream and the reactant stream occurs in the presence of steam, nitrogen, or a combination thereof in a dealkylation reaction zone.

[0033]

[0035] In some embodiments, transalkylating the bottoms stream and the reactant stream occurs in a first transalkylation reaction zone in the presence of hydrogen, nitrogen, steam, or combinations thereof.

[0034]

[0036] In some embodiments, the dealkylation catalyst comprises a heterogeneous acid catalyst, or the first transalkylation catalyst comprises a heterogeneous acid catalyst, or both.

[0037] In some embodiments, at least one of the first dealkylation reaction zone and the first transalkylation reaction zone comprises a fixed bed reactor, a moving bed reactor, an ebullated bed reactor, a fluidized bed reactor, a continuous catalyst regeneration (CCR) reactor, a semi-regenerative reactor, a batch reactor, a continuous stirred tank (CSTR) reactor, a slurry reactor, or a combination thereof.

[0035]

[0038] Another aspect of the invention is a method for producing phenol from a coal-derived feedstock. In one embodiment, the method includes the steps of providing an alkylphenol stream comprising alkylphenols having alkyl chains with 2 or more carbon atoms; dealkylating the alkylphenol stream in a first dealkylation reaction zone comprising a first dealkylation reactor under first dealkylation reaction conditions in the presence of a first dealkylation catalyst to produce a first dealkylated effluent stream comprising light hydrocarbons, alkylbenzenes, phenol, cresols, and unconverted alkylphenols; separating the first dealkylated effluent stream in a dealkylation separation zone comprising at least a phenol stream comprising phenol, a bottoms stream comprising unconverted alkylphenols, and transalkylating the bottoms stream and a reactant stream comprising toluene or benzene or both in a first transalkylation reaction zone comprising a first transalkylation reactor under first transalkylation reaction conditions in the presence of a first transalkylation catalyst to produce a first transalkylated effluent stream comprising cresols, phenol, and alkylbenzenes; introducing the first transalkylated effluent stream into a dealkylation separation zone; and recovering a phenol stream.

[0036]

[0039] In some embodiments, the method includes the steps of: separating the cresol stream from the dealkylation separation zone in a cresol separation zone into a mixed cresol stream comprising p-cresol and o-cresol, and an m-cresol stream comprising m-cresol; isomerizing the mixed cresol stream in a cresol isomerization reaction zone under cresol isomerization reaction conditions in the presence of a cresol isomerization catalyst to form a cresol isomerization effluent stream comprising a mixture of cresols; recycling the cresol isomerization effluent stream to the cresol separation zone; recovering the m-cresol stream comprising m-cresol; separating the alkylbenzene stream from the dealkylation separation zone in an alkylbenzene separation zone into at least a recycle stream comprising one or more of benzene and toluene, a heavy alkylbenzene stream comprising an alkylbenzene having an alkyl chain having two or more carbon atoms, and a mixed xylene stream comprising a mixture of xylene and ethylbenzene; recycling the recycle stream from the alkylbenzene separation zone to the first transalkylation reaction zone; separating the mixed xylene stream in a xylene isomerization reaction zone into a second xylene stream comprising ethylbenzene, o-xylene, and m-xylene, and a p-xylene stream comprising p-xylene; isomerizing the second xylene stream in a xylene isomerization reaction zone under xylene isomerization reaction conditions in the presence of a xylene isomerization catalyst to form a xylene isomerization effluent stream comprising a mixture of xylenes; recycling the xylene isomerization effluent stream to the xylene separation zone; recovering the p-xylene stream; and reacting the second xylene stream in the presence of a second dealkylation catalyst under xylene isomerization reaction conditions to form a xylene isomerization effluent stream comprising a mixture of xylenes. dealkylating the heavy alkylbenzene stream in a second dealkylation reaction zone comprising a second dealkylation reactor under second transalkylation conditions in the presence of a second transalkylation catalyst to form a dealkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene or both; or transalkylating the heavy alkylbenzene stream in a second transalkylation reaction zone under second transalkylation conditions in the presence of a second transalkylation catalyst to form a transalkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene or both;and recycling the dealkylated heavy alkylbenzene effluent stream, the transalkylated heavy alkylbenzene effluent stream, or both to the alkylbenzene separation zone;

[0037]

[0040] In some embodiments, providing an alkylphenol stream includes providing a coal-derived feed stream to a first separation zone; and separating the coal-derived feed stream in the first separation zone into an alkylphenol stream, and at least one of a first phenol stream comprising phenol, and a first cresol stream comprising cresol.

[0038]

[0041] In some embodiments, the first dealkylation reaction conditions are a temperature in the range of 50° C. to 700° C., a pressure in the range of 0 MPa(g) to 5 MPa(g), and a reaction time of 0.1 to 300 h. -1 or the first transalkylation reaction conditions include a temperature in the range of 50° C. to 600° C., a pressure in the range of 0 MPa(g) to 15 MPa(g), and a reaction time of 0.1 to 300 h -1 or both.

[0039]

[0042] A schematic flow diagram of one embodiment of the integrated process 100 is shown in Figure 1. A feed stream 105 comprising the acid fraction and crude phenols from the coal-derived liquids is sent to a first separation zone 110 where it is separated into a phenols stream 115 comprising phenol, a cresol stream 120 comprising cresol, and an alkylphenols stream 125 comprising alkylphenols having alkyl chains with two or more carbon atoms. Suitable first separation processes include, but are not limited to, distillation, extraction, adsorption, extractive distillation, crystallization, membrane separation, or combinations thereof.

[0040]

[0043] The alkylphenol stream 125 is passed to a first dealkylation reaction zone 130 which comprises one or more dealkylation reactors having a dealkylation catalyst.

[0044] Dealkylation can be carried out with or without a catalyst. Alkylphenols can be dealkylated without a catalyst by thermal cracking at high temperatures. Dealkylation without a catalyst can be very energy intensive, since the temperatures range from 400-900°C, often 700-900°C. Furthermore, it is often not selective due to the loss of the hydroxyl group.

[0041]

[0045] Catalytic dealkylation of heavy alkylphenols can be carried out at much milder conditions. Typical temperatures range from 100 to 700°C, or from 200 to 540°C. Ethylphenol and propylphenol can be dealkylated at temperatures of 300 to 400°C to produce phenol and ethylene / propylene, for example, over ZSM-5 zeolite. Debutylation of alkylphenols has also been reported on acidic clay catalysts. Any suitable dealkylation catalyst can be used, including, but not limited to, silica alumina, acidic clay, zeolites, gamma alumina, chromium oxide, other metal oxides or mixed metal oxides, or combinations thereof.

[0042]

[0046] The pressure for the dealkylation is generally in the range of 1-5 MPa(a). The dealkylation reaction may also be carried out under reduced pressure, e.g., typically 50 kPa(a), up to 20 kPa(a). The weight hourly space velocity (WHSV) is typically in the range of 1-5 hr -1 The range is.

[0043]

[0047] Water / steam may be co-fed to prevent severe catalyst deactivation. Dealkylation is usually carried out in superheated steam. Typical steam to alkylphenol weight ratios range from 0.1:1 to 10:1, or 0.5:1 to 5:1.

[0044]

[0048] The first dealkylated effluent stream 135 is a mixture of light hydrocarbons (C 1 ~C 7 These include hydrocarbons, such as ethylene, propylene, etc., alkylbenzenes, phenols, cresols, and unconverted alkylphenols.

[0045]

[0049] The first dealkylation effluent stream 135 is separated in the dealkylation separation zone 140 into at least a phenol stream 145 comprising phenol, and a bottoms stream 150 comprising unconverted alkylphenols. The first dealkylation effluent stream 135 may optionally be separated into one or more additional streams, such as a light hydrocarbon stream 155 comprising light hydrocarbons, an alkylbenzene stream 160 comprising alkylbenzenes, a cresol stream 165 comprising cresols, and a process water stream 170 comprising water. Suitable dealkylation separation processes include, but are not limited to, distillation, extractive distillation, adsorption, crystallization, membrane separation, or combinations thereof.

[0046]

[0050] A phenol stream 145 from the first dealkylation separation zone 140 may be recovered.

[0051] Bottoms stream 150 is sent to a first transalkylation reaction zone 175 where it is transalkylated with a reactant feed stream 180 comprising benzene and / or toluene. First transalkylation reaction zone 175 comprises one or more transalkylation reactors.

[0047]

[0052] When the catalyst is used for the transalkylation of alkylphenols, the temperature is typically in the range of 50 to 600°C, or 100 to 500°C. The transalkylation zone is typically operated at a pressure in the range of about 0 MPa(g) to 15 MPa(g), or 2 MPa(g) to 11 MPa(g). The weight hourly space velocity (WHSV) is generally in the range of 0.1 to 300 hr -1 , or 1~250hr -1 The range is.

[0048]

[0053] The catalyst is typically selected to have relatively high stability at high activity levels. Suitable transalkylation catalysts include, but are not limited to, zeolites, acidic clays, silica aluminas, acidic resins, mixed metal oxides, and the like, as are known in the art.

[0049]

[0054] The ratio of benzene / toluene to phenol (molar ratio) is from 0.1:1 to 20:1, alternatively from 0.5:1 to 10:1, alternatively from 1:1 to 5:1.

[0055] The first transalkylated effluent stream 185, containing cresols, phenols, and alkylbenzenes, is sent to the dealkylation separation zone 140 for separation.

[0050]

[0056] The alkylbenzene stream 160 may be sent to an alkylbenzene separation zone 190 where it is separated into at least a recycle stream 195 comprising one or more of benzene and toluene, a heavy alkylbenzene stream 200 comprising alkylbenzenes having alkyl chains with two or more carbon atoms, and a mixed xylenes stream 205 comprising a mixture of xylenes and ethylbenzene. Suitable alkylbenzene separation processes include, but are not limited to, distillation, extractive distillation, or a combination thereof.

[0051]

[0057] The recycle stream 195 may be sent to the first transalkylation reaction zone 175 .

[0058] The heavy alkylbenzene stream 200 may be sent to a second dealkylation reaction zone or a second transalkylation reaction zone 210 or both, where the heavy alkylbenzene stream 200 is dealkylated or transalkylated.

[0052]

[0059] Heavy alkylbenzene dealkylation reaction conditions typically include temperatures ranging from 0° C. to 600° C., or from 100° C. to 500° C. The heavy alkylbenzene dealkylation zone is typically operated at pressures ranging from about 0 MPa(g) to 7.6 MPa(g), or from 0.01 MPa(g) to 5 MPa(g). The WHSV is generally in the range of 0.01 to 200 hr -1 , or 0.1 to 100 hours -1Any suitable heavy alkylbenzene dealkylation catalyst may be used. The catalyst is typically selected to have relatively high stability at high activity levels. Suitable heavy alkylbenzene dealkylation catalysts include, but are not limited to, zeolites, acidic clays, silica aluminas, acidic resins, mixed metal oxides, and the like, as are known in the art.

[0053]

[0060] Heavy alkylbenzene transalkylation reaction conditions typically include temperatures ranging from 0°C to 600°C, or 100°C to 500°C. Heavy alkylbenzene transalkylation is typically carried out at pressures ranging from about 0 MPa(g) to 15 MPa(g), or 1 MPa(g) to 11 MPa(g). The WHSV is generally between 0.1 and 300 hr -1 , or 0.2 to 200 hours -1 Any suitable heavy alkylbenzene transalkylation catalyst may be used. The catalyst is typically selected to have relatively high stability at high activity levels. Suitable heavy alkylbenzene transalkylation catalysts include, but are not limited to, zeolites, acidic clays, silica aluminas, acidic resins, mixed metal oxides, and the like, as are known in the art.

[0054]

[0061] The dealkylated effluent stream 215 comprises one or more of benzene, toluene, and xylenes, and / or the transalkylated effluent stream 215 comprises one or more of benzene, toluene, and xylenes.

[0055]

[0062] The mixed xylenes stream 205 may be sent to a xylene separation zone 220 where it is separated into a p-xylene stream 225 comprising p-xylene, and a second mixed xylenes stream 230 comprising ethylbenzene, o-xylene, and m-xylene. The p-xylene stream 225 may be recovered.

[0056]

[0063] Any suitable xylene separation process may be used, including, but not limited to, distillation, adsorption (e.g., UOP's Parex™ process), crystallization (e.g., BP / CBI's pX process), or a combination of these processes.

[0057]

[0064] The second mixed xylenes stream 230 is sent to a xylene isomerization zone 240 for isomerization of o-xylene and m-xylene. A xylene isomerization effluent stream 245 comprising the mixture of xylenes is sent to the xylene separation zone 220. The xylene isomerization zone 240 comprises one or more xylene isomerization reactors.

[0058]

[0065] Suitable xylene isomerization processes include, but are not limited to, UOP's Isomar™ process.

[0066] The xylene isomerization reaction zone 240 normally operates at reaction conditions including temperatures ranging from 50° C. to 600° C., or from 100° C. to 500° C. The xylene isomerization zone is typically operated at moderately elevated pressures over a wide range, from 0 MPa to 7.6 MPa gauge, or from 0.01 MPa to 5 MPa gauge. The xylene isomerization reaction may be carried out over a variety of liquid hourly space velocities (LHSV). LHSVs are generally in the range of 0.1 to 5 hr -1 , or 0.2 to 4 hours -1 In some embodiments, the xylene isomerization reaction is carried out at a temperature ranging from 50° C. to 600° C., a pressure ranging from 0 MPa(g) to 7.6 MPa(g), and a reaction time ranging from 0.1 to 5 hr. -1 In some embodiments, the xylene isomerization reaction occurs under reaction conditions including a temperature in the range of 100° C. to 500° C., a pressure in the range of 0.01 MPa(g) to 5 MPa(g), and a reaction time in the range of 0.2 to 4 hr -1 This occurs under reaction conditions involving LHSVs in the range of

[0059]

[0067] Any suitable xylene isomerization catalyst may be used. A suitable xylene isomerization catalyst is BF 3These catalysts include, but are not limited to, both homogeneous catalysts such as -HF, and heterogeneous catalysts such as amorphous silica alumina, zeolites, or metal promoted zeolites. The catalysts are typically selected to have relatively high stability at high activity levels.

[0060]

[0068] Cresol stream 165 may be sent to cresol separation zone 250 where it is separated into mixed cresol stream 255, comprising p-cresol and o-cresol, and m-cresol stream 260, comprising m-cresol. Cresol stream 120 may also be sent to cresol separation zone 250. m-cresol stream 260 may be recovered.

[0061]

[0069] Suitable cresol separation processes include, but are not limited to, distillation, crystallization, adsorption (eg, UOP's Cresex™ adsorption process), or combinations thereof.

[0062]

[0070] The mixed cresol stream 255 is sent to a cresol isomerization zone 265 for isomerization of p-cresol and o-cresol. A cresol isomerization effluent stream 270 comprising a mixture of cresols is sent to the cresol separation zone 250.

[0063]

[0071] Cresol isomerization reaction conditions typically include temperatures ranging from 50°C to 600°C, or from 100°C to 500°C. The cresol isomerization zone is typically operated at pressures ranging from about 0 MPa(g) to 15 MPa(g), or from 0.01 MPa(g) to 10 MPa(g). The WHSV is generally in the range of 0.1 to 200 hr -1 , or 0.2 to 100 hours -1 The range is.

[0064]

[0072] Any suitable cresol isomerization catalyst can be used. The cresol isomerization catalyst is typically selected to have a relatively high stability at a high activity level. Suitable cresol isomerization catalysts include, but are not limited to, zeolites, acidic clays, silica aluminas, acidic resins, and mixed metal oxides, as known in the art.

[0065]

[0073] Figure 2 illustrates another embodiment, an integrated process 300. Process 300 is similar to process 100 shown in Figure 1. The difference is that feed stream 105 is separated in first separation zone 110 into a phenols stream 115, a cresol stream 120, an alkylphenol stream 125, and a xylenol stream 305 comprising xylenol and trimethylphenol. Xylenol stream 305 may be sent to first transalkylation reaction zone 175 along with bottoms stream 150 from dealkylation separation zone 140, reactant feed stream 180, and recycle stream 195 from alkylbenzene separation zone 190. Xylenol is converted to phenol and cresol in first transalkylation reaction zone 175.

[0066]

[0074] 2 (with a direct co-feed of a xylenol stream from first separation zone 110 to first transalkylation reaction zone 175) may reduce the equipment size of the dealkylation process, which also provides more flexibility in plant operations to meet market needs for the xylenol product. EXAMPLES

[0067]

[0075] The product yields for toluene transalkylation and dealkylation predicted from computer simulations using Honeywell UniSim Design software are summarized in Table 1. The calculations assume an overall conversion of 98% for the dealkylation and a toluene recycle ratio of 95% for the transalkylation.

[0068]

[0076] The product profile of the dealkylation is based only on the alkylphenols in the feedstock and not on the xylenols.

[0069] [Table 1]

[0070]

[0077] Using Honeywell UniSim Design, the predicted product profile of the proposed integrated process is compared to toluene transalkylation alone in Table 2. The phenol yield is increased by up to about 26 wt% by the integrated process. The phenol yield in the integrated case (Case 1) is increased by about 100% compared to the toluene transalkylation case (Case 0). The phenol yield is maximized when all xylenol from the first separation zone is obtained as a product and does not participate in the transalkylation with toluene. The yield of alkylbenzene is reduced from 56.5 wt% in Case 0 to 15 wt% in Case 2. Thus, in Case 2, phenol becomes the main product, not alkylbenzene, which is desirable in a phenol plant.

[0071] [Table 2]

[0072]

[0078] As used herein, the term "zone" may refer to an area that includes one or more pieces of equipment and / or one or more subzones. The equipment may include one or more reactors or reaction vessels, heaters, exchangers, piping, pumps, compressors, and controllers. Additionally, equipment such as reactors, dryers, or vessels may further include one or more zones or subzones.

[0073]

[0079] As used herein, the term "about" means within 10%, including, or within 5%, or within 1% of a value.

[0080] As depicted, the process flow lines in the diagrams are referred to interchangeably as, for example, lines, pipes, branches, distributors, streams, effluent, feed, product, sections, catalyst, withdrawal, recycle, suction, exhaust, and caustic.

[0074]

[0081] Although at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it will be recognized that numerous variations exist. It should also be recognized that the exemplary embodiment or embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the invention in any manner. Instead, the foregoing detailed description will provide those skilled in the art with a convenient guide for implementing the exemplary embodiments of the invention. It will be understood that various changes may be made in the function and arrangement of elements described in the exemplary embodiments without departing from the scope of the invention as set forth in the appended claims.

Claims

1. 1. A process for producing phenol from a coal-derived feedstock, comprising: providing an alkylphenol stream comprising alkylphenols having alkyl chains with 2 or more carbon atoms; dealkylating the alkylphenol stream in a first dealkylation reaction zone comprising a first dealkylation reactor under first dealkylation reaction conditions in the presence of a first dealkylation catalyst to produce a first dealkylation effluent stream comprising light hydrocarbons, alkylbenzenes, phenol, cresols, and unconverted alkylphenols; separating the first dealkylated effluent stream in a dealkylation separation zone into at least a phenol stream comprising phenol and a bottom stream comprising unconverted alkylphenols; transalkylating the bottoms stream and a reactant stream comprising toluene or benzene or both in a first transalkylation reaction zone comprising a first transalkylation reactor under first transalkylation reaction conditions in the presence of a first transalkylation catalyst to produce a first transalkylation effluent stream comprising cresols, phenols, and alkylbenzenes; introducing the first transalkylated effluent stream into a dealkylation separation zone; recovering the phenol stream; A method comprising:

2. 2. The method of claim 1, wherein separating the first dealkylated effluent stream in the dealkylation separation zone comprises separating the first dealkylated effluent stream into a phenol stream, a bottoms stream, and at least one of a cresol stream comprising cresol, a light hydrocarbon stream comprising light hydrocarbons, and an alkylbenzene stream comprising alkylbenzene.

3. separating the cresol stream in a cresol separation zone into a mixed cresol stream comprising p-cresol and o-cresol, and an m-cresol stream comprising m-cresol; isomerizing the mixed cresol stream in a cresol isomerization reaction zone under cresol isomerization reaction conditions in the presence of a cresol isomerization catalyst to form a cresol isomerization effluent stream comprising a mixture of cresols; recycling the cresol isomerization effluent stream to the cresol separation zone; recovering an m-cresol stream comprising m-cresol; The method of claim 2 , further comprising:

4. separating the alkylbenzene stream in an alkylbenzene separation zone into at least a recycle stream comprising one or more of benzene and toluene, a heavy alkylbenzene stream comprising alkylbenzenes having alkyl chains having two or more carbon atoms, and a mixed xylenes stream comprising a mixture of xylenes and ethylbenzene; recycling the recycle stream from the alkylbenzene separation zone to the first transalkylation reaction zone. The method of claim 2 , further comprising:

5. separating the mixed xylene stream in a xylene separation zone into a second xylene stream comprising ethylbenzene, o-xylene, and m-xylene, and a p-xylene stream comprising p-xylene; isomerizing the second xylene stream in a xylene isomerization reaction zone under xylene isomerization reaction conditions in the presence of a xylene isomerization catalyst to form a xylene isomerization effluent stream comprising a mixture of xylenes; recycling the xylene isomerization effluent stream to the xylene separation zone; recovering the p-xylene stream; The method of claim 4 further comprising:

6. dealkylating the heavy alkylbenzene stream in a second dealkylation reaction zone comprising a second dealkylation reactor under second dealkylation conditions in the presence of a second dealkylation catalyst to form a dealkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene, or both; or transalkylating the heavy alkylbenzene stream in a second transalkylation reaction zone comprising a second transalkylation reactor under second transalkylation conditions in the presence of a second transalkylation catalyst to form a transalkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene, or both; optionally recycling the dealkylated heavy alkylbenzene effluent stream, the transalkylated heavy alkylbenzene effluent stream, or both to an alkylbenzene separation zone; The method of claim 5 further comprising:

7. 7. The process of any one of claims 1 to 6, wherein the bottom stream from the dealkylation separation zone further comprises toluene or xylenol or both.

8. Providing an alkylphenol stream comprises: providing a coal-derived feed stream to a first separation zone; separating the coal-derived feed stream in a first separation zone into at least one of an alkylphenol stream, a first phenol stream comprising phenol, and a first cresol stream comprising cresol; The method of any one of claims 1 to 7, comprising:

9. 10. The method of claim 8, wherein separating the coal-derived feed stream comprises separating the coal-derived feed stream by one or more of extraction, absorption, extractive distillation, crystallization, or membrane separation.

10. 9. The method of claim 8, wherein the coal-derived feed stream comprises a low temperature coal tar stream, a medium temperature coal tar stream, a high temperature coal tar stream, a cresylic acid stream, or a portion of a crude phenol mixture.

11. The first dealkylation reaction conditions are a temperature in the range of 50° C. to 700° C., a pressure in the range of 0 MPa(g) to 5 MPa(g), and a time in the range of 0.1 to 300 hr. －１ 11. The method of claim 1 , comprising one or more of the WHSVs in the range:

12. The first transalkylation reaction conditions are a temperature in the range of 50° C. to 600° C., a pressure in the range of 0 MPa(g) to 15 MPa(g), and a time in the range of 0.1 to 300 hr. －１ 12. The method of claim 1 , comprising one or more of the WHSVs in the range:

13. 13. The method of any one of claims 1 to 12, wherein the step of dealkylating the alkylphenol stream and the reactant stream occurs in the presence of steam, nitrogen, or a combination thereof in a dealkylation reaction zone.

14. 14. The method of any one of claims 1 to 13, wherein the step of transalkylating the bottoms stream and the reactant stream occurs in the presence of hydrogen, nitrogen, steam, or combinations thereof in a first transalkylation reaction zone.

15. 15. The process of any one of claims 1 to 14, wherein the dealkylation catalyst comprises a heterogeneous acid catalyst, or the first transalkylation catalyst comprises a heterogeneous acid catalyst, or both.

16. 16. The process of any one of claims 1 to 15, wherein at least one of the first dealkylation reaction zone and the first transalkylation reaction zone comprises a fixed bed reactor, a moving bed reactor, an ebullated bed reactor, a fluidized bed reactor, a continuous catalyst regeneration (CCR) reactor, a semi-regenerative reactor, a batch reactor, a continuous stirred tank (CSTR) reactor, a slurry reactor, or a combination thereof.

17. 1. A process for producing phenol from a coal-derived feedstock, comprising: providing an alkylphenol stream comprising alkylphenols having alkyl chains with 2 or more carbon atoms; dealkylating the alkylphenol stream in a first dealkylation reaction zone comprising a first dealkylation zone under first dealkylation reaction conditions in the presence of a first dealkylation catalyst to produce a first dealkylation effluent stream comprising light hydrocarbons, alkylbenzenes, phenol, cresols, and unconverted alkylphenols; separating the first dealkylation effluent stream in a dealkylation separation zone into at least a phenol stream comprising phenol, a bottoms stream comprising unconverted alkylphenols, and at least one of a cresol stream comprising cresols, a light hydrocarbon stream comprising light hydrocarbons, and an alkylbenzene stream comprising alkylbenzenes; transalkylating the bottoms stream and a reactant stream comprising toluene or benzene or both in a first transalkylation reaction zone comprising a first transalkylation reactor under first transalkylation reaction conditions in the presence of a first transalkylation catalyst to produce a first transalkylation effluent stream comprising cresols, phenols, and alkylbenzenes; introducing the first transalkylated effluent stream into a dealkylation separation zone; recovering the phenol stream; Including, the coal-derived feed stream comprises a low temperature coal tar stream, a medium temperature coal tar stream, a high temperature coal tar stream, a cresylic acid stream, or a portion of a crude phenol mixture; method.

18. separating the cresol stream from the dealkylation separation zone in a cresol separation zone into a mixed cresol stream comprising p-cresol and o-cresol, and an m-cresol stream comprising m-cresol; isomerizing the mixed cresol stream in a cresol isomerization reaction zone under cresol isomerization reaction conditions in the presence of a cresol isomerization catalyst to form a cresol isomerization effluent stream comprising a mixture of cresols; recycling the cresol isomerization effluent stream to the cresol separation zone; recovering an m-cresol stream comprising m-cresol; separating the alkylbenzene stream from the dealkylation separation zone in an alkylbenzene separation zone into at least a recycle stream comprising one or more of benzene and toluene, a heavy alkylbenzene stream comprising alkylbenzenes having alkyl chains having two or more carbon atoms, and a mixed xylenes stream comprising a mixture of xylenes and ethylbenzene; recycling a recycle stream from the alkylbenzene separation zone to the first transalkylation reaction zone; separating the mixed xylene stream in a xylene separation zone into a second xylene stream comprising ethylbenzene, o-xylene, and m-xylene, and a p-xylene stream comprising p-xylene; isomerizing the second xylene stream in a xylene isomerization reaction zone under xylene isomerization reaction conditions in the presence of a xylene isomerization catalyst to form a xylene isomerization effluent stream comprising a mixture of xylenes; recycling the xylene isomerization effluent stream to the xylene separation zone; recovering a p-xylene stream; dealkylating the heavy alkylbenzene stream in a second dealkylation reaction zone comprising a second dealkylation reactor under second dealkylation conditions in the presence of a second dealkylation catalyst to form a dealkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene, or both; or transalkylating the heavy alkylbenzene stream in a second transalkylation reaction zone comprising a second transalkylation reactor under second transalkylation conditions in the presence of a second transalkylation catalyst to form a transalkylated heavy alkylbenzene effluent stream comprising xylenes, and benzene or toluene, or both; recycling the dealkylated heavy alkylbenzene effluent stream, the transalkylated heavy alkylbenzene effluent stream, or both to an alkylbenzene separation zone; 20. The method of claim 17, further comprising:

19. Providing an alkylphenol stream comprises: providing a coal-derived feed stream to a first separation zone; separating the coal-derived feed stream in a first separation zone into at least one of an alkylphenol stream, a first phenol stream comprising phenol, and a first cresol stream comprising cresol; 19. The method of any one of claims 17 to 18, comprising:

20. The first dealkylation reaction conditions are a temperature in the range of 50° C. to 700° C., a pressure in the range of 0 MPa(g) to 5 MPa(g), and a time in the range of 0.1 to 300 hr. －１ or The first transalkylation reaction conditions are a temperature in the range of 50° C. to 600° C., a pressure in the range of 0 MPa(g) to 15 MPa(g), and a time in the range of 0.1 to 300 hr. －１ or Both 20. The method according to any one of claims 17 to 19.

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