TW201604273A - Process for producing styrene-, methylstyrene- and ethylbenzene-free C6-C9 aromatic hydrocarbon blends - Google Patents

Abstract

Various substantially styrene-, methylstyrene- and ethylbenzene-free C6-C9 aromatic hydrocarbon blends are produced from a hydrocarbon feed stream containing C5-C9 aromatic hydrocarbons including styrene, methylstyrene and sulphur compounds by first separating the stream into a distillate containing C5-C7 hydrocarbons, and a bottoms fraction containing C8 and C9 hydrocarbons; and converting the styrene and methylstyrene to their corresponding ethers by reacting with a C1-C3 lower alcohol in the presence of a selective acidic etherification catalyst. The effluent may be sent to a gasoline pool for blending or the effluent is separated by distillation into an ether stream and either a C8 or a C8-C9 aromatic hydrocarbon rich stream. The C5-C7 distillate is hydrogenated.

Description

Method for preparing a C6-C9 aromatic hydrocarbon blend without styrene, methyl styrene and ethylbenzene

The present invention relates to a process for the selective preparation of various C6 substantially free of styrene, methylstyrene and ethylbenzene from a hydrocarbon feed stream comprising a C5-C9 hydrocarbon comprising styrene, methylstyrene and a sulfur compound. -C9 aromatic hydrocarbon blends, and especially with respect to methods for preparing C6-C7, C6-C9 and C6-C8 aromatic hydrocarbon blends. The sulfur compounds are distributed throughout the range of C5 to C9 boiling points.

Refining liquid hydrocarbons and fractionation provides a series of hydrocarbon product streams. Further refining a stream such as a hydrocarbon feed, a non-hydrotreated pyrolysis gasoline from a steam cracker, FCC naphtha or a non-hydrotreated coker naphtha to provide a C6-C8 aromatic blend ( Often referred to as BTX), it primarily comprises a mixture of benzene, toluene, ethylbenzene, styrene, and xylene. For example, a method for the preparation of BTX from FCC naphtha is described in U.S. Patent No. 5,685,972 issued to Timken et al.

BTX is a valuable raw material for the manufacture of petrochemicals and polymers and is also used as a fuel for internal combustion engines. However, its styrene content tends to polymerize and form a compound that interferes with BTX as a chemical feedstock, or a higher molecular weight compound that would interfere with its formation into a binder residue for combustion. Therefore, when BTX is used as a petrochemical raw material or as a liquid fuel for an internal combustion engine, it is undesirable to have styrene present in BTX. The styrene content in BTX is reduced by hydrogenation to ethylbenzene. Timken et al., 5,685,972, describe the "hydrorefining" stage in the conversion of FCC naphtha to BTX and high octane gasoline.

However, ethylbenzene and styrene have lower value when burned as a fuel. BTX with styrene removed has a higher value than BTX containing styrene. In addition, when styrene is recycled for use in the manufacture of polymers or petrochemicals, it is of higher value when compared to converting styrene to ethylbenzene for use as a fuel. To date, methods such as those disclosed in U.S. Patent Nos. 3,953,300, 4,031,153 and 5,849,982 are not effective in removing and recovering styrene from BTX fractions containing a large amount of sulfur compounds such as pyrolysis gasoline and FCC gasoline. This is because styrene reacts more readily with hydrogen than thiophene sulphur in the hydrotreating process, which is the only way commercially to desulfurize purified styrene.

The prior publication, Effective Au (III) catalysted addition of alcohols to alkenes, Royal Society of Chemistry 2007, Chem. Commun. 2007, 3080-3082, is described in priority to the addition of one of the alcohols such as methanol and ethanol to C8 or C9 aromatics. A C9 ether is formed. See Table 1 (entry 9 versus entry 1).

There is a need for a process for removing styrene and methyl styrene from C5-C9 hydrocarbon blends more efficiently than current refining and separation processes. This is accomplished by removing both styrene and methyl styrene prior to the second stage hydrogenation reactor to minimize the formation of EB (hydrogenation from styrene). The ability to increase the hydrogenation reactor is removed and the separation of downstream xylene is much easier. One such method is described in US Patent Application Serial No. 13/373,094, filed on Nov. 4, 2011, the disclosure of which is hereby incorporated by reference. In this process, styrene is removed by etherification to the corresponding ether which is reacted with a C1-C3 lower alcohol such as methanol or ethanol in the presence of a suitable acidic catalyst which is selective for etherification. achieve. It should be noted that the process described therein is limited to the preparation of C6-C8 aromatic hydrocarbons (BTX) which are substantially free of styrene.

Accordingly, Applicants have now developed a more versatile method for the selective preparation of various C6-C9 aromatic hydrocarbon blends substantially free of styrene, methyl styrene and ethylbenzene.

According to one aspect of the invention, there is provided a process for the selective preparation of various substantially free styrene, methyl styrene from a hydrocarbon feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound. And a method of blending a C6-C9 aromatic hydrocarbon product of ethylbenzene comprising (a) providing a feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound, and (b) a distillation feed stream To provide a distillate containing C5-C7 hydrocarbons and a distillation residue containing C8-C9 hydrocarbons including styrene and methyl styrene, (c) to make a distillation residue with a C1 to C3 lower alcohol in styrene (C8) And methyl ether styrene (C9) etherified in the presence of a selective acidic catalyst to form its corresponding ether, (d) optionally distilled (as the case may be, the effluent from the case 1 is distilled) The ether is removed and a distillate containing C8 (this is Case 3) or C8 and C9 (this is Case 2) are provided depending on the reaction conditions. The ether and C8-C9 inert/hydrocarbon are transferred to the gasoline pool.

(e) hydrogenation of distillates containing C5-C7 hydrocarbons (case 1) in the presence of a suitable catalyst (as appropriate with distillates containing C8 aromatics (case 3) or distillates containing C8 and C9 aromatics (case 2) The product is combined to convert the diolefin to a monoolefin, (f) to distill the resulting effluent to remove the C5 hydrocarbon, (g) to hydrogenate the effluent in the presence of a suitable catalyst to convert the monoolefin to a saturated alkane and to convert the sulfur compound Hydrogen sulfide is formed, and hydrogen sulfide is removed, and (h) the resulting effluent is subjected to liquid-liquid extraction to separate a selected C6-C9 aromatic hydrocarbon product blend substantially free of styrene, methyl styrene and ethylbenzene. .

It should be noted that the first hydrogenation step uses a catalyst which is inert to the conversion of the sulfur compound to H ₂ S. Is converted into H ₂ S occurs only in the second hydrogenation step, i.e., the sulfur compounds prior to the second hydrogenation step is present in all stream.

In addition, the solvent used in the liquid-liquid extraction step is a suitable polar aprotic solvent, preferably used in most refineries, usually called cyclobutanthene 2,3,4,5-tetrahydrothiophene-1,1- Dioxide Things. However, it should be understood that other similar solvents may also be used.

According to a specific embodiment of this aspect of the invention, there is provided a process wherein the selected C6-C9 aromatic hydrocarbon product blend is a C6-C7 aromatic hydrocarbon blend, hereinafter referred to as Case 1, the method comprising (a) providing a feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound, (b) a distillation feed stream to provide a distillate containing C5-C7 hydrocarbons and comprising styrene and methyl styrene a distillation residue of C8 and C9 hydrocarbons, (c) reacting a distillation residue with a C1-C3 lower alcohol in the presence of an acidic catalyst selective for the etherification of styrene (C8) and methyl styrene (C9) Forming its corresponding ether, (d) hydrogenating the distillate stream in the presence of a suitable catalyst to convert the diolefin to a monoolefin to produce a C5-C7 hydrocarbon containing substantially no styrene, methyl styrene and ethylbenzene The effluent, (e) distilling the resulting effluent containing C5-C7 hydrocarbons to remove C5 hydrocarbons, (f) hydrogenating the resulting effluent containing C6-C7 aromatics in the presence of a suitable catalyst to convert the monoolefins to saturated alkanes And converting the sulfur compound to hydrogen sulfide and removing hydrogen sulfide, and (g) performing liquid liquid on the obtained effluent Extraction is performed to separate a C6-C7 aromatic hydrocarbon blend substantially free of styrene, methyl styrene, and ethylbenzene.

According to another embodiment of this aspect of the invention, hereinafter referred to as Case 2, the selected C6-C9 aromatic product blend is a C6-C9 aromatic blend, the method comprising (a) providing a styrene comprising a feed stream of a C5-C9 hydrocarbon of methyl styrene and a sulfur compound, (b) a distillation feed stream to provide a distillate stream comprising C5-C7 hydrocarbons and comprising Distillation residue of C8 and C9 hydrocarbons of styrene and methyl styrene, (c) distillation residue in the presence of an acidic catalyst selective for etherification of styrene (C8) and methyl styrene (C9) Reaction with a C1-C3 lower alcohol to form its corresponding ether, (d) distillation of an effluent containing inert C8 and C9 hydrocarbons and styrene and methylstyrene ether to remove ether and produce a distillate containing C8-C9 hydrocarbons And (e) hydrogenating the combined C5-C7 distillate and C8-C9 distillate in the presence of a suitable catalyst to convert the diolefin to a monoolefin to produce a substantially free styrene, methyl styrene and An effluent of C5-C9 hydrocarbons of ethylbenzene, (f) distilling the resulting effluent to remove C5 hydrocarbons, (g) hydrogenating the resulting effluent containing C6-C9 aromatics in the presence of a suitable catalyst to convert the monoolefins to saturation Alkanes and the conversion of sulfur compounds to hydrogen sulfide and removal of hydrogen sulfide, and (h) liquid-liquid extraction of the resulting effluent to separate C6-C9 aromatics substantially free of styrene, methylstyrene and ethylbenzene Compound.

According to another embodiment of this aspect of the invention, wherein the selected C6-C9 aromatic hydrocarbon product blend is a C6-C8 hydrocarbon blend, hereinafter referred to as Case 3, the method comprising (a) providing a benzene comprising a feed stream of C5-C9 hydrocarbons of ethylene, methyl styrene and sulfur compounds, (b) a distillation feed stream to provide a distillate containing C5-C7 hydrocarbons and a C8 comprising styrene and methyl styrene and a distillation residue of C9 hydrocarbons, (c) reacting a distillation residue with a C1-C3 lower alcohol to form a phase in the presence of an acidic catalyst selective for the etherification of styrene (C8) and methyl styrene (C9) Corresponding ether, (d) distillation containing inert C8 and C9 hydrocarbons and styrene (C8) and methyl benzene An olefin (C9) ether effluent to remove inert C9 and ether and to produce a C8 aromatics-containing distillate, (e) to hydrogenate the combined C5-C7 distillate and C8 distillate in the presence of a suitable catalyst Converting the diolefin to a monoolefin to produce an effluent containing C5-C8 hydrocarbons substantially free of styrene, methyl styrene and ethylbenzene, (f) distilling the resulting effluent containing C5-C8 hydrocarbons to remove C5 a hydrocarbon, (g) hydrogenating the resulting effluent containing a C6-C8 aromatic hydrocarbon in the presence of a suitable catalyst to convert the monoolefin to a saturated alkane and to convert the sulfur compound to hydrogen sulfide and remove hydrogen sulfide, and (h) the resulting The effluent is subjected to liquid-liquid extraction to separate a C6-C8 aromatic hydrocarbon blend substantially free of styrene, methylstyrene and ethylbenzene.

It should be noted that although methanol or ethanol is a preferred C1-C3 lower alcohol, a C3 alcohol may also be used. However, it is more expensive.

In some embodiments of the invention, the selective etherification catalyst is a sulfonic acid based polymeric cation exchange resin. In other embodiments of the invention, the acidic catalyst is a sulfonic acid based on a crosslinked styrene divinylbenzene copolymer, a macroreticular polymeric resin, such as sold under the registered trademarks of Amberlyst 15WET, 35WET and 70 by Rohm & Haas. By. These materials are well known to be selective for etherification reactions. For example, Amberlyst 15WET is used to prepare MTEB and ETBE, so its reliability is well known. It should be noted that the 15WET, 35WET and 70 names are used for variants that are suitable for use at different reaction temperatures. For example, Amberlyst 15WET is ideal for etherification at up to 100 °C, Amberlyst 35WET is ideal for etherification at temperatures up to 140 °C, and Amberlyst 70 is at the higher end of the temperature range, ie Amberlyst 70 Suitable for etherification reactions up to 170 °C. The details of the properties of these materials are available in the Rohm & Haas catalogue available under the AMBERLYST polymerization catalyst. Nafion® SAC-13 is another polymeric acidic sulfonic acid catalyst that can be used. However, its activity is lower than that of the Amberlyst series.

In other embodiments of the invention, in the temperature range of 80 ° C to 140 ° C The etherification reaction is achieved. Amberlyst 15WET is stable over a temperature range of 80 ° C to 120 ° C. I have found that 100 ° C is the best because of the high selectivity for styrene and methyl styrene ether.

In another embodiment of the invention, a molar excess of alcohol is used. Preferably, when the alcohol is methanol (MeOH), the molar ratio of MeOH:styrene is 5:1.

It is also contemplated that inorganic acidic catalysts such as sulfated zeolites can be used to catalyze etherification but have lower activity.

It will be apparent from the following [embodiments] of the present invention that the composition of the product stream depends on the choice of the design of the reactor system in which the process is to be carried out.

For a fuller understanding of the invention, and in the claims

1 is a schematic flow diagram of a prior art process for BTX preparation; FIG. 2 is a view of the invention for selectively preparing a C6-C7 arene blend substantially free of styrene, methyl styrene, and ethylbenzene. A schematic flow diagram of a first specific example of the method, hereinafter referred to as Case 1; Figure 3 is a scheme for the selective preparation of a C6-C9 aromatic hydrocarbon blend substantially free of styrene, methylstyrene and ethylbenzene. A schematic flow diagram of a second embodiment of the inventive method, hereinafter referred to as Case 2; Figure 4 is a selective preparation of a C6-C8 aromatic hydrocarbon blend substantially free of styrene, methyl styrene, and ethylbenzene. A schematic flow diagram of a third embodiment of the process of the present invention, hereinafter referred to as Case 3; Figure 5 is a graphical illustration of a one-stage plug flow etherification reactor for simulating the synthesis of methanol-styrene and methylstyrene ether; Figure 6 is a graph illustrating the concentration distribution along the length of the reactor of Figure 5; Figure 7 is a two-stage simulation for the synthesis of methanol-styrene and methylstyrene ether. Schematic diagram of a plug flow reactor; Figures 8 and 9 are graphs illustrating concentration distributions along respective lengths of the two reactors of Figure 7; Figures 10 and 11 are specific examples of isothermal ESE synthesis, illustrating A graph of the concentration distribution along the length of the two reactors of Figure 7; Figures 12 and 13 are graphs showing the concentration and temperature distribution in the two reactors of Figure 7 for a specific example of adiabatic MSE synthesis; Figure 14 and Figure 15 is a graph illustrating the concentration and temperature distribution in the two reactors of Fig. 7 for specific examples of adiabatic ESE synthesis; and Fig. 16 is a graph illustrating the conversion of styrene to styrene ether using various catalysts of the present invention.

FIG. 1 schematically illustrates a typical process for preparing a BTX 50 having a reduced styrene content from a hydrocarbon feed 22. Hydrocarbon feed 22 can be any refinery stream containing a light aromatic having a higher styrene content, such as pyrolysis gasoline, FCC naphtha, or coker naphtha that has not been hydrotreated.

The apparatus 10 for use in the process has a series of reactors and columns comprising: a first stage hydrogenation reactor 12, a first distillation column 14, a second distillation column 16, a second stage hydrogenation reactor 18, and a liquid-liquid extraction zone 20 .

The styrene-containing hydrocarbon feed 22 is fed through a feed line 24 to a first stage hydrogenation reactor 12 where it is reacted with a hydrogen gas 26 fed through a hydrogen feed line 28 via a first stage catalyst. The catalyst is conventionally supported on alumina Pd or Ni to convert the diolefins in hydrocarbon feed 22 to monoolefins. The product stream 34 from this reactor is fed to a first distillation column 14 where it is separated into a light fraction 30 comprising primarily C5 hydrocarbons and a liquid distillation residue 36. The liquid distillation residue 36 is fed to a second distillation column 16 where it is separated into a heavier fraction 38 comprising C9 and higher hydrocarbons and a lighter fraction 42 comprising BTX, ethylbenzene and styrene. The lighter fraction 42 is fed to a second stage hydrogenation reactor 18 where it is reacted with hydrogen 26 via a second stage catalyst. The catalyst is a conventional two-layer catalyst comprising a NiMo upper layer and a CoMo lower layer to convert olefins to paraffins and to convert sulfur compounds to hydrogen sulfide. The hydrogen sulfide thus formed is removed from the mixture downstream of the second stage hydrogenation reactor 18. The product stream 44 of the second stage hydrogenation reactor 18 is fed to a liquid-liquid extraction zone 20 where it is separated into a light-depleted residue 46 and a product 50 comprising BTX and a minor amount of ethylbenzene. This is the method used in most refineries today. Hydrogenation of styrene (increased H ₂ consumption) into ethylbenzene (low value). The advantages of the present invention are enumerated later.

Referring to Figures 2 through 4, three specific examples of the present invention (referred to as Cases 1 through 3) will now be described, and the performance and advantages of the present invention over the prior art methods illustrated in Figure 1 will be shown.

Case 1

This specific example of the invention relates to the preparation of a C6-C7 arene blend substantially free of styrene, methylstyrene and ethylbenzene.

As seen in Figure 2, a hydrocarbon feed 22 comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound is fed to a distillation column 102 to provide a distillate comprising predominantly C5-C7 hydrocarbons and is enriched in C8. And a C9 hydrocarbon and containing a distillation residue of styrene and methyl styrene.

Since the distillate does not contain any C8 and does not actually contain styrene, hydrogen consumption is reduced in subsequent hydrogenation reactors 110 and 112. It should be noted that the hydrogenation reactor is a limiting step in the recovery of the C6-C9 aromatics blend. Emphasize that the distillation column can be adjusted to separate any compounds (or groups of compounds) in the feed. The only requirement is that the boiling point is different. For example, since C5-C6 is combined with other low boiling C8 and C9 aromatics in the feed, we can obtain individual C5 or obtain C5-C7 aromatics depending on process parameters. In addition, for hydrocarbons, the boiling point increases as the carbon number increases. This is why styrene (C8) ether and methyl styrene (C9) ether are easier to use than styrene and C9 hydrocarbon itself. Separation of xylene.

The distillation residue is then fed to an etherification reactor 106 containing a C1-C3 lower alcohol 134, preferably methanol or ethanol, and styrene (C8) and methyl styrene via an acidic catalyst selective for etherification. (C9) is converted to its corresponding ether. The resulting effluent 136 can be passed to a gasoline pool for blending.

The selective etherification catalyst has been found to be preferably an acidic resin such as Amberlyst 15®. It should be noted that in the following examples, we used a power equation developed from laboratory data to predict conversion rates for different methanol and ethanol to styrene/methylstyrene ratios. (See the results shown in Tables 4, 6 and 7).

The C5-C7 distillate is fed together with hydrogen 26 into a first stage hydrogenation reactor 110 where it is reacted via a first stage hydrogenation catalyst. The catalyst is conventionally supported on alumina Pd or Ni to primarily convert C5 diolefins (such as isoprene and cyclopentadiene) in hydrocarbon feed 22 to monoolefins.

The effluent from the hydrogenation reactor 110 comprising C5-C7 aromatics is fed to distillation column 104 to remove the C5 compound as distillate 120 and to provide a distillation residue comprising C6-C7 aromatics.

The C6-C7 distillation residue is then fed to a second stage hydrogenation reactor 112 where the sulfur compound is hydrogenated by hydrogen 26 in the presence of a second stage hydrogenation catalyst to saturate the olefin (not the benzene ring) to a saturated hydrocarbon. And the sulfur compound is desulfurized to form gaseous hydrogen sulfide. The catalyst is a conventional two-layer catalyst comprising a NiMo upper layer and a CoMo lower layer.

It will be appreciated that the first and second stage hydrogenation reactors operate under reaction conditions suitable for the various reaction conditions and catalysts employed. It should be noted that since the styrene and methylstyrene were removed by conversion to ether, followed by distillation but prior to hydrogenation, the feed to the hydrogenation reactor contained little or no styrene and methylstyrene. Thus, the hydrogenation requirements are reduced compared to the prior art and the capacity of the hydrogenation reactor is increased due to the lower flow rate.

Hydrogen sulfide is removed from the effluent downstream of reactor 112.

The effluent from the hydrogenation reactor 112 containing the removed hydrogen sulphide is then fed to a liquid-liquid extraction column 114 where it is separated into light effluents 154 comprising paraffin and naphthenes and comprising substantially no Product 150 of an A6-A7 (benzene-toluene) arene blend of styrene, methyl styrene and ethylbenzene. It should be understood that this product simplifies the downstream preparation of para-xylene (PX). This process will produce A6-A7 by removing C8 and C9 prior to hydrogenation, thus greatly reducing the loading on hydrogenation reactors 110 and 112. See the examples below.

Case 2

This specific example of the invention relates to the preparation of a C6-C9 aromatic hydrocarbon blend substantially free of styrene, methylstyrene and ethylbenzene.

As seen in Figure 3, a hydrocarbon feed 22 comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound is fed to a distillation column 102 to provide a distillate comprising predominantly C5-C7 hydrocarbons and is enriched. C8 and C9 hydrocarbons and contain a distillation residue of styrene and methyl styrene.

Since the distillate does not contain any C8 and does not actually contain styrene or methyl styrene, hydrogen consumption is reduced in subsequent hydrogenation reactors 110 and 112. It should be noted that the hydrogenation reactor is a limiting step in the recovery of the C6-C9 aromatics blend. In addition, it should be noted that due to the large difference in boiling point (the boiling point of the ether is much higher), the removal of styrene and methylstyrene by conversion to its corresponding ether facilitates separation by distillation prior to hydrogenation. In addition, since styrene and methyl styrene have been removed from the feed to the hydrogenation reactor 110 by etherification, the effluent therefrom is substantially free of ethylbenzene and is directed to the hydrogenation reactors 110 and 112. The material contains little or no styrene (C8) and methyl styrene (C9). Therefore, the hydrogenation requirement is substantially reduced and the capacity of the hydrogenation reactor is increased due to the lower flow rate.

The distillation residue from column 102 is then fed to an etherification reactor 106 containing a C1-C3 lower alcohol 134, preferably methanol or ethanol, and styrene and methylbenzene are passed via an acidic catalyst selective for etherification. Ethylene is converted to its corresponding ether.

The selective etherification catalyst has been found to be preferably an acidic resin such as Amberlyst 15(TM). See catalyst descriptions elsewhere.

The thus formed C8 and C9 ethers are fed to a distillation column 108 which separates a distillation residue 136 containing C8 and C9 ethers and C8 and C9 inert hydrocarbons. The distillation raffinate can be passed to a gasoline pool for blending and the distillate containing C8 and C9 aromatics can be passed to the first stage hydrogenation reactor 110.

The distillate from distillation column 102 containing C5-C7 hydrocarbons is also passed to a first stage hydrogenation reactor 110 where the combined C5-C7 and C8-C9 distillates are passed through hydrogen 26 The stage hydrogenation catalyst is hydrogenated. The catalyst is conventionally supported on alumina Pd or Ni to convert diolefins such as isoprene and cyclopentadiene to monoolefins.

The effluent from the hydrogenation reactor 110 comprising C5-C9 hydrocarbons but substantially free of ethylbenzene is fed to distillation column 104 to remove the C5 compound as distillate 120 and to provide a distillation residue comprising C6-C9 aromatics.

The C6-C9 distillation residue is then fed to a second stage hydrogenation reactor 112 where the olefinic compound is hydrogenated to a saturated hydrocarbon by hydrogen 26 and the sulfur compound is converted to gaseous sulfurization in the presence of a second stage hydrogenation catalyst. hydrogen. The catalyst is a conventional two-layer catalyst comprising a NiMo upper layer and a CoMo lower layer.

It will be appreciated that the first and second stage hydrogenation reactors operate under reaction conditions suitable for different reaction conditions, including temperature, and the catalyst employed.

Hydrogen sulfide is removed from the effluent downstream of reactor 112.

The effluent from the hydrogenation reactor 112 containing the removed hydrogen sulfide is then fed to a liquid-liquid extraction column 114 where it is separated into light-collected residues comprising C6-C9 saturated hydrocarbons (paraffin and naphthenic). 154 and product 150 comprising an A6-A9 arene blend substantially free of styrene, methyl styrene, and ethylbenzene. It should be noted that no reaction involves liquid-liquid extraction (LLE). As with the boiling point in the distillation, the compound in the apparent feed is determined by the solubility of the solvent added to the LLE column.

It is also indicated that C7 and C9 aromatics can be separated and used to produce valuable products. C8 aromatics.

Case 3

This specific example of the invention relates to the preparation of a C6-C8 aromatic hydrocarbon blend substantially free of styrene, methyl styrene and ethylbenzene.

As seen in Figure 4, a hydrocarbon feed 22 comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound is fed to a distillation column 102 to provide a distillate comprising a C5-C7 hydrocarbon and containing a sulfur compound. And a distillation residue rich in C8 and C9 hydrocarbons and containing styrene and methyl styrene.

Since the distillate does not contain any C8 and does not actually contain styrene or methyl styrene, hydrogen consumption is reduced in subsequent hydrogenation reactors 110 and 112. It should be noted that the hydrogenation reactor is a limiting step in the recovery of the C6-C9 aromatics blend. In addition, it should be noted that due to the large difference in boiling point (the boiling point of the ether is much higher), the removal of styrene and methylstyrene by conversion to its corresponding ether facilitates separation by distillation prior to hydrogenation. Additionally, the feed to hydrogenation reactors 110 and 112 contains little or no styrene and methyl styrene. Therefore, the hydrogenation requirement is substantially reduced and the capacity of the hydrogenation reactor is increased due to the lower flow rate.

The distillation residue is then fed to an etherification reactor 106 containing a C1-C3 lower alcohol 134, preferably methanol or ethanol, and styrene (C8) and methyl styrene via an acidic catalyst selective for etherification. (C9) is converted to its corresponding ether.

The selective etherification catalyst has been found to be preferably an acidic resin such as Amberlyst 15®. See other details about the catalyst.

The inert C9 and C8 and C9 ethers thus formed are then fed to a distillation column 108 which separates a distillation residue 136 containing inert C9 and C8 and C9 ethers and C8 inert hydrocarbons. The distillation raffinate can be passed to a gasoline pool for blending and the distillate containing C8 aromatics can be passed to the second stage hydrogenation reactor 112.

The distillate from the distillation column 102 containing C5-C7 hydrocarbons is also transferred to the first stage Hydrogenation reactor 110, in which the combined distillate is hydrogenated via hydrogen 26 via a first stage hydrogenation catalyst. The catalyst is conventionally supported on alumina Pd or Ni to convert diolefins (such as isoprene and cyclopentadiene) in hydrocarbon feed 22 to monoolefins.

The effluent from the hydrogenation reactor 110 comprising C5-C8 hydrocarbons but substantially free of ethylbenzene is fed to distillation column 104 to remove the C5 compound as distillate 120 and to provide a distillation residue comprising C6-C8 aromatics.

The C6-C8 distillation raffinate is then fed to a second stage hydrogenation reactor 112 where the olefinic compound is hydrogenated to a saturated hydrocarbon by hydrogen 26 and the sulfur compound is converted to a gaseous sulfide in the presence of a second stage hydrogenation catalyst. hydrogen. The catalyst is a conventional two-layer catalyst comprising a NiMo upper layer and a CoMo lower layer.

It will be appreciated that the first and second stage hydrogenation reactors operate under reaction conditions suitable for the various reaction conditions and catalysts employed.

Hydrogen sulfide is removed from the effluent downstream of reactor 112.

The effluent from the hydrogenation reactor 112 containing the removed hydrogen sulfide is then fed to a liquid-liquid extraction column 114 where it is separated into light-collected residues comprising C6-C8 saturated hydrocarbons (paraffin and naphthenic). 154 and product 150 comprising an A6-A8 arene blend substantially free of styrene, methyl styrene, and ethylbenzene.

It has been found through experiments that the selective etherification catalyst is preferably an acidic resin such as Amberlyst 15® resin when the reaction (1) is carried out at about 100 °C. Testing of a BTX feed containing about 33% styrene and 67% xylene showed minimal difference in activity when using Amberlyst 15WET or 35WET.

C ₆ H ₅ CH=CH ₂ +CH ₃ OH←→C ₆ H ₅ CH(CH ₃ )OCH ₃ (1)

As shown in Fig. 16, other similar acidic resin catalysts as described above can also be used. Specifically, Figure 16 illustrates the use of 10 g of various catalysts at a temperature of 100 ° C at a molar ratio of MeOH:styrene of 5:1, styrene to styrene at a stirrer speed of 1000 rpm. The conversion of ether.

The concern is that methanol can be converted to methyl ether via an etherification catalyst (Scheme 2). The absence of detectable products (by GC) from such reactions was determined experimentally as indicated by the products listed in the tables in the examples. The results indicate that the catalyst is more selectively oriented towards the formation of styrene ether than towards the formation of methyl ether.

_{2 CH 3 OH ← → (CH} 3) 2 O + H 2 O (2)

The following detailed description contains information obtained through laboratory experiments and simulations using ASPEN PLUS® software. Computer simulation should be understood as a proof of concept for the present invention.

The process modeled using ASPEN PLUS® has been characterized based on the results of the laboratory experiments illustrated in Figures 6 to 16 and the following examples, and the advantages have been confirmed.

The advantages of the process operation of the present invention when compared to prior art processes for various aromatic blends are: The cerium (C6-C9) product blend contains ethylbenzene which is rarely derived from the hydrogenation of styrene. In prior art processes, containing a large amount of ethylbenzene is typically C ₈ aromatics separated or transferred to the gasoline pool, and thus have a lower value. If the residual aromatic ethylbenzene while C ₈ was the amount was too high, the downstream processing (e.g. purification of mixed xylenes) the increased cost.

The removal of most of the styrene and methyl styrene prior to treatment of the stream in the hydrogenation reactor reduces the volume that must be treated via their reactors, and thus increases the reaction for processing the desired materials. The capacity of the device. This is extremely important because the hydrogenation reactor is typically a capacity bottleneck in the naphtha cracker or gas oil cracker process.

In addition, low levels of residual styrene and methyl styrene extend the operational life of the catalyst in the hydrogenation reactor.

Niobium does not need to consume hydrogen to convert styrene to ethylbenzene and thus hydrogen consumption is reduced for the entire process.

Indole styrene and methyl styrene ether can be blended into gasoline as an oxygenate Improve combustion characteristics or decompose back to styrene and methanol (reverse of Reaction Equation 1).

Example

Model reaction for liquid phase catalytic reactor for A8 and A9 etherification

The following experiment describes a model reaction that supports the following arguments: in the presence of a suitable acidic catalyst selective for the etherification reaction, styrene (C8) and methylstyrene (C9) arenes are made with C1- such as methanol or ethanol. The C3 lower alcohol is converted to its corresponding ether.

Example 1

Methylstyrene ether synthesis-isothermal reactor

ASPEN PLUS® (version 7.1) RPlug reactor model was used to model the plug flow reaction of styrene (A8) with methanol to form methanol styrene ether (MSE) (ie 1-methoxyethylbenzene) (PFR). The laboratory rate data for the reaction in the xylene solvent is shown to be proportional to the styrene concentration and inversely proportional to the methanol concentration. The methanol adsorption effect is considered to account for the rate of increase at low methanol concentrations, while also explaining the inhibition of methanol at very high methanol concentrations. The reaction model also considers the reverse reaction by including an equilibrium constant (Keqm) obtained from the literature (Verevkin et al, J. Chem. Eng. Data, 46, 984-990, 2001). The NRTL-RK characteristic method is used for gas-liquid equilibrium calculations. Binary interaction parameters were estimated for binary pairs containing MSE and styrene-methanol. The reaction of 4-methylstyrene (A9) with methanol to form 1-(4-methylphenyl)ethyl methyl ether (4MMSE) was modeled as a side reaction. The reaction rate was estimated from the conversion data obtained in the literature (Zhang and Corma, Royal Society of Chemistry, 2007, Chem. Commun. 2007, 3080-3082). Since no two product components (MSE and 4MMSE) were found in the ASPEN PLUS® database, the boiling temperature and other critical constants were estimated using Aspen Properties using the GANI group contribution method. In this case, the reactor was designed as a constant temperature PFR operating at 100 °C. It was sized such that the flow rate of styrene in the feed mixture having a mass fraction of 0.2433 in styrene in xylene was 1 mol/h. Including the presence of an inert mass fraction of 0.1957, afford the ₉ H ₁₂ C the reaction components and modeled as 1-methyl-ethylbenzene. Figure 5 is a schematic representation of a one-stage plug flow reactor 402 for the synthesis of methanol styrene ether. Feed 406 contains styrene, methyl styrene, and inert C8 and C9 compounds. The effluent 410 from reactor 402 is passed to distillation column 107 to separate methanol and unreacted feed compound 409 from product ether 136 due to the use of methanol to feed ratio that exceeds stoichiometric requirements. Stream 409 is recycled and mixed with feed 406 and methanol stream 405. Mixture 407 then enters reactor 402.

Table 1 shows the operating parameters of the reactor. The tower was designed to operate at a pressure of 4 standard atmospheres and a temperature of 100 °C. Figure 6 shows the liquid composition distribution along the length of the column and the temperature distribution along the column. Table 2 summarizes the material flow for the PFR reactor. The styrene conversion in the PFR reactor was 81.85% with a total residence time of 24 minutes. The total feed ratio of methanol to styrene in the process was 1.5:1.

Example 2

An alternative configuration provides two plug flow reactors 402 and 404 connected in series; this will allow another methanol feed 408 along the length of the reactor. A schematic of this configuration is shown in Figure 7.

Both PFR1 (402) and PFR2 (404) operate at the same temperature and pressure as the single PFR (402) of Figure 5. The methanol is separated into a stream 405 and a stream 408 between the two reactors. Figures 8 and 9 show the concentration distribution along the length of the reactor.

Finally, Table 3 shows the effect of increasing the methanol concentration to achieve higher styrene conversion. At a molar feed ratio of 3:1 (methanol:styrene), a styrene conversion of greater than 95% was achieved even in the first PFR. However, the results also show that increasing the methanol feed ratio is also detrimental to the conversion of 4-methylstyrene. Since the MeOH feed was increased from 1.5 moles per hour to 3 moles per hour, the conversion of 4-methylstyrene was reduced from 93.35% to 55.66%. Also in order to achieve high 4-methylstyrene conversion, it is preferred to further feed another MeOH downstream, and thus two plug flow reactor tandem models are proposed. In comparing the two series plug flow reactors (PFR1 and PFR2), it was seen that the optimum methanol feed was evenly separated between PFR1 and PFR2.

Example 3

Ethylene styrene ether synthesis-isothermal reactor

The simulation was also carried out for the reaction of styrene with ethanol to form ethanol styrene ether (ESE) (i.e., 1-ethoxyethylbenzene). It is assumed that in these examples the ethanol always exceeds styrene, and thus the power rate equation is modeled in terms of the second order power law depending on both styrene and ethanol concentrations. The reverse reaction is explained by the equilibrium constant (Keqm) obtained from the literature (Verevkin, 2001). Also included is a side reaction of 4-methylstyrene with ethanol. The total ethanol/styrene feed varied from 3:1 to 6:1. A second-order model was used in this experiment, including a constant temperature of 100 ° C and a pressure of 4 standard atmospheres.

The ethanol/styrene feed ratio was presented as 5:1, with the result of feeding to PFR1 at 3 moles/hour and feeding to PFR2 at 2 moles/hour. The concentration distribution along the length of the reactor is shown in Figures 10 and 11. The total styrene conversion was 95.4% and the 4-methylstyrene conversion was 100%. Table 6 shows the results for conversion of styrene and 4-methylstyrene to other feed ratios for ethanol.

From Table 6, it can be seen that the molar ratio of ethanol/styrene of 5:1 is sufficient to achieve a conversion of >95% of styrene and methylstyrene.

Example 4

Adiabatic MSE reactor

Previous simulations using the device of Figure 7, constant reactor temperature based on 100 ° C get on. Since the MSE reaction is exothermic, it will be necessary to provide cooling to the reactor to maintain a constant temperature. If the plug flow reactor is operated adiabatically, the heat of reaction is integrated into the design of the reactor and does not create additional costs for cooling the reactor. The feed stream was preheated to 70 °C and rose to about 110 °C in reactor 402 and rose to about 120 °C in reactor 404 during operation. Table 5 shows the results of varying the methanol feed.

Figures 12 and 13 show the concentration and temperature distribution in the molar ratios PFR1 and PFR2 for 3:1 (methanol and styrene). The total conversions of styrene and 4-methylstyrene were 94.3% and 98.0%, respectively.

Example 5

Adiabatic ESE reactor

The adiabatic ESE reactor was operated with a molar ratio of ethanol to styrene of 5:1 and with the feed entering at 80 °C. The ethanol feed to reactor 402 (PFR1) was 3 moles per hour and the ethanol feed to reactor 404 (PRF2) was 2 moles per hour. All other operating strips The pieces are the same. Figures 14 and 15 show the concentration and temperature distribution along the length of the reactor. The conversion rates of total styrene and 4-methylstyrene were 95.4% and 99.9%, respectively.

22‧‧‧ hydrocarbon feed

26‧‧‧ Hydrogen

102‧‧‧Distillation tower

104‧‧‧Distillation tower

106‧‧‧etherification reactor

110‧‧‧First Stage Hydrogenation Reactor

112‧‧‧Second stage hydrogenation reactor

114‧‧‧ Liquid-Liquid Extraction Tower

120‧‧‧ distillate

134‧‧‧C1-C3 lower alcohol

136‧‧‧ product ether

150‧‧‧ products

154‧‧‧Light extraction

Claims (23)

A method for selectively preparing various C6-C9 aromatic hydrocarbon products substantially free of styrene, methyl styrene and ethylbenzene from a hydrocarbon feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound a method of blending comprising: (a) distilling a feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene, and a sulfur compound to produce a distillate comprising a C5-C7 hydrocarbon and comprising styrene and a distillation residue of C8-C9 hydrocarbon of methyl styrene, (b) reacting the distillation residue with a C1-C3 lower alcohol in the presence of an acidic catalyst selective for etherification of styrene and methyl styrene a corresponding ether, (c) optionally distilling the resulting effluent to remove the ether and providing a distillate comprising C8 or C8 and C9 aromatics, (d) hydrogenating the C5-containing compound in the presence of a suitable catalyst a C7 hydrocarbon distillate (as appropriate with the C8 aromatics-containing distillate or the C8 and C9 aromatics-containing distillate) to convert the diolefin to a monoolefin, (e) to distill the resulting effluent to shift In addition to the C5 hydrocarbons, (f) hydrogenates the effluent in the presence of a suitable catalyst to convert the monoolefin to a saturated alkane and will cure Converting to hydrogen sulfide and removing the hydrogen sulfide, and (g) liquid-liquid extraction of the resulting effluent to separate the selected C6-C9 substantially free of styrene, methyl styrene and ethylbenzene Aromatic hydrocarbon product blend. The method of claim 1, wherein in the step (b), the C1-C3 lower alcohol is methanol or ethanol. The method of claim 2, wherein in the step (b), the acidic catalyst is a sulfonic acid based on a crosslinked divinylbenzene copolymer, a macroreticular polymeric resin. The method of claim 3, wherein in the solvent extraction step, the solvent is a polar aprotic solvent. The method of claim 4, wherein the solvent is 2,3,4,5-tetrahydrothiophene-1,1-dioxide. A method for selectively preparing a C6-C7 aromatic hydrocarbon product substantially free of styrene, methyl styrene and ethylbenzene from a hydrocarbon feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound And a method comprising: (a) distilling a feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound to produce a distillate comprising a C5-C7 hydrocarbon and comprising styrene and a a distillation residue of C8 and C9 hydrocarbons of styrene, (b) reacting the distillation residue with a C1-C3 lower alcohol in the presence of an acidic catalyst selective for etherification of styrene and methylstyrene to form Corresponding ether, (c) hydrogenating the distillate stream in the presence of a suitable catalyst to convert the diolefin to a monoolefin to produce a C5-C7 hydrocarbon containing substantially no styrene, methyl styrene and ethylbenzene. An effluent, (d) distilling the resulting effluent containing C5-C7 hydrocarbons to remove the C5 hydrocarbons, (e) hydrogenating the resulting effluent containing C6-C7 aromatics in the presence of a suitable catalyst to convert the monoolefins a saturated alkane, and converting the sulfur compound into gaseous hydrogen sulfide and removing the hydrogen sulfide, and (f) The resulting effluent was subjected to liquid-liquid extraction to separate a C6-C7 aromatic hydrocarbon blend substantially free of styrene, methylstyrene and ethylbenzene. The method of claim 6, wherein in the step (b), the C1-C3 lower alcohol is methanol or ethanol. The method of claim 7, wherein in the step (b), the acidic catalyst is a sulfonic acid based on a crosslinked divinylbenzene copolymer, a macroreticular polymeric resin. The method of claim 8, wherein in the solvent extraction step, the solvent is a polar aprotic solvent. The method of claim 9, wherein the solvent is 2,3,4,5-tetrahydrothiophene-1,1-dioxide. A method for selectively preparing a C6-C9 aromatic hydrocarbon product substantially free of styrene, methyl styrene and ethylbenzene from a hydrocarbon feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound And a method comprising: (a) distilling a feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound to produce a distillate stream comprising C5-C7 hydrocarbons and comprising styrene and a distillation residue of C8 and C9 hydrocarbons of styrene, (b) reacting the distillation residue with a C1-C3 lower alcohol in the presence of an acidic catalyst selective for etherification of styrene and methylstyrene to form Corresponding ether, (c) distilling the effluent containing inert C8 and C9 hydrocarbons and styrene and methyl styrene ether to remove the ether and produce a distillate containing C8 and C9 hydrocarbons, (d) The combined C5-C7 distillate and C8-C9 distillate are hydrogenated in the presence of a catalyst to convert the diolefin to a monoolefin to produce a C5-containing substantially no styrene, methyl styrene and ethylbenzene. An effluent of C9 hydrocarbons, (e) distilling the resulting effluent to remove C5 hydrocarbons, (f) hydrogenating the C containing hydrogen in the presence of a suitable catalyst The resulting effluent of 6-C9 hydrocarbon to convert the monoolefin to a saturated alkane and to convert the sulfur compound to gaseous hydrogen sulfide and remove the hydrogen sulfide, and (g) liquid-liquid extraction of the resulting effluent to separate the substantial There is no C6-C9 aromatic hydrocarbon blend of styrene, methyl styrene and ethylbenzene. The method of claim 11, wherein in the step (b), the C1-C3 lower alcohol is methanol or ethanol. The method of claim 12, wherein in the step (b), the acidic catalyst is a sulfonic acid based on a crosslinked divinylbenzene copolymer, a macroreticular polymeric resin. The method of claim 13, wherein in the solvent extraction step, the solvent is a polar aprotic solvent. The method of claim 14, wherein the solvent is 2,3,4,5-tetrahydrothiophene-1,1-dioxide. A method for selectively preparing a C6-C8 aromatic hydrocarbon product substantially free of styrene, methyl styrene and ethylbenzene from a hydrocarbon feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound And a method comprising: (a) distilling a feed stream comprising a C5-C9 hydrocarbon comprising styrene, methyl styrene and a sulfur compound to produce a distillate comprising a C5-C7 hydrocarbon and comprising styrene and a a distillation residue of C8 and C9 hydrocarbons of styrene, (b) reacting the distillation residue with a C1-C3 lower alcohol in the presence of an acidic catalyst selective for etherification of styrene and methylstyrene to form Corresponding ether, (c) distilling the effluent containing inert C8 and C9 hydrocarbons and styrene and methyl styrene ether to remove inert C9 and the ethers, and producing a distillate containing C8 aromatics, (d The combined C5-C7 distillate and C8 distillate are hydrogenated in the presence of a suitable catalyst to convert the diolefin to a monoolefin to produce a C5-containing substantially no styrene, methyl styrene and ethylbenzene. An effluent of C8 hydrocarbons, (e) distilling the resulting effluent containing C5-C8 hydrocarbons to remove the C5 hydrocarbons, (f) suitable for The resulting effluent containing C6-C8 hydrocarbons is hydrogenated in the presence of an agent to convert the monoolefins to saturated alkanes and to convert the sulfur compounds to gaseous hydrogen sulfide and to remove the hydrogen sulfide, and (g) to flow out the proceeds The liquid-liquid extraction was carried out to separate a C6-C8 aromatic hydrocarbon blend substantially free of styrene, methylstyrene and ethylbenzene. The method of claim 16, wherein in the step (b), the C1-C3 lower alcohol is methanol or ethanol. The method of claim 17, wherein in the step (b), the acidic catalyst is a sulfonic acid based on a crosslinked divinylbenzene copolymer, a macroreticular polymeric resin. The method of claim 18, wherein in the solvent extraction step, the solvent is a polar aprotic solvent. The method of claim 19, wherein the solvent is 2,3,4,5-tetrahydrothiophene-1,1-dioxide. The method of claim 3, wherein in the step (b), the etherification reaction is carried out at a temperature of from 80 ° C to 120 ° C. The method of claim 21, wherein in the step (b), excess MeOH:styrene is used. The method of claim 21, wherein about 5:1 MeOH: styrene or EtOH: styrene molar ratio is used in step (b).