A method of processing heavy aromatic hydrocarbons

 

(57) Abstract:

The invention relates to a method for conversion of heavy aromatic hydrocarbons to lighter aromatic compounds such as benzene, by contacting the fraction WITH9+ aromatic hydrocarbons and toluene above the first catalyst containing a zeolite having an index of permeability of 0.5 - 3, and a hydrogenation component and a second catalyst composition comprising a zeolite with an average size of pores having an index of permeability 3 - 12, the ratio of silica to alumina of at least 5, this reduces the number or preventing the formation of jointly boiling compounds. The technical result - getting benzene of high purity, the increase in output. 2 c. and 5 C.p. f-crystals, 1 Il., table 1.

The invention relates to a method for conversion of heavy aromatic hydrocarbons, in particular WITH9+ aromatic hydrocarbons to lighter aromatic products. In particular, the invention relates to the production of benzene, having a high level of purity.

Source of benzene and xylene is the product of catalytic reforming, which is obtained by mixing the naphtha from vadora moderately acidic substrate, such as processed halogen aluminum. Usually the product of reforming separate the fraction from C6to C8conduct solvent extraction, selective with respect to aromatic or aliphatic hydrocarbons, in order to separate the connection of these two classes and receive a mixture of aromatic hydrocarbons practically free from aliphatic compounds. This mixture of aromatic compounds typically contains benzene, toluene and xylenes (BTX) along with ethylbenzene.

Refineries also focused on the production of benzene and xylene by transaminirovania9+ aromatic hydrocarbons and toluene over zeolite catalysts containing noble metals. During the process of transformation WITH9+ aromatic hydrocarbons and toluene by transaminirovania more valuable petrochemical products, such as benzene and xylene, over catalysts containing noble metals, usually within the first few months in the flow produces by-products in the form of saturated compounds. These side saturated compounds defined together as boiling, can boil in the same temperature range as Cenacolo product, as benzene for commercial sale must exceed of 99.85%. However, the initial purity of the product such as benzene after distillation of the reaction product of transaminirovania is usually only to 99.2 to 99.5% due to the presence together of boiling compounds, such as Methylcyclopentane, cyclohexane, 2,3-dimethylpentane, dimethylcyclopentane and 3-methylhexan. Therefore, to further increase the purity of the benzene product to the required level usually requires an additional stage of extraction.

Due to the difficulties in obtaining petrochemical products containing benzene of high purity due to the presence together of boiling products formed in the process of transaminirovania9+ aromatic hydrocarbons and toluene over a noble metal containing zeolite catalysts, it is desirable to reduce the concentration jointly boiling products, which are formed in the process of transaminirovania. The advantage of reducing the concentration jointly boiling compounds formed in the process of transaminirovania, is that such a product as benzene can be obtained with a high degree of purity after distillation of the reaction product transliterate process, which are necessary for the production of benzene having a purity level of at least 99,85%.

The present invention in General relates to a method for conversion of heavy aromatic hydrocarbons to lighter aromatic compounds. In particular, the present invention is directed to a method of reducing the concentration jointly boiling compounds, which are formed in the process of transaminirovania heavy aromatic hydrocarbons, namely9+ aromatic hydrocarbons and toluene, benzene and xylene.

The invention relates to a method of transforming raw materials containing9+ aromatic hydrocarbons and toluene, in a product containing benzene and xylene, which involves the step of contacting the material containing C9+ aromatic hydrocarbons and toluene, the reaction conditions of transaminirovania with a first catalyst composition comprising a zeolite having an index of permeability, in the range of 0.5 - 3, and a hydrogenation component and a second catalyst composition comprising a zeolite with an average size of pores having an index of permeability, in the range 3 - 12, the ratio of silica to alumina of at least 5, with getting PR is at least 99,85%, can be obtained by distillation of the benzene from the product of the process of transaminirovania without the need for the extraction step.

The drawing shows a typical technological scheme of the process of transaminirovania.

The present invention in General is directed to the process of transformation of heavy aromatic hydrocarbons to lighter aromatic products.

In particular, the present invention is directed to a method of reducing the concentration jointly boiling compounds, which are formed in the process of transaminirovania heavy aromatic hydrocarbons, namely9+ aromatic hydrocarbons and toluene, benzene and xylene, to obtain the reaction product of transaminirovania containing benzene and xylene. The benzene product having a purity level of at least 99,85%, can be obtained by distillation of the benzene from the product of the process of transaminirovania without the need for the extraction step.

A feature of the invention, which achieves benzene of high purity, is to reduce or prevent the formation of jointly boiling products when transalkylating heavy aromatic zeolite, with the index of the permeability of 0.5 to 3, and a hydrogenation component and a second catalyst composition comprising a zeolite with an average size of pores having an index of permeability 3 - 12, the ratio of silicon dioxide to aluminum oxide constituting at least 5. The method, according to which determine the index of the permeability of the zeolite, is fully described in US 4016218.

The advantages in terms of reducing or preventing the formation of jointly boiling compounds in the process of transaminirovania heavy aromatic hydrocarbons and toluene to benzene and xylene is that excluded the stage of extraction, which is usually required in the case of the production of benzene of high purity.

The first catalytic composition

The reaction that underlies this invention is catalyzed by contact with a first catalyst composition comprising a zeolite having an index of permeability of 0.5 - 3. Zeolites which are particularly relevant include zeolites brand MCM-22, PSH-3, SSZ-25, ZSM-12, and zeolite beta.

Zeolite beta is particularly described in US Re 28341 (patent US 3308069).

ZSM-12 is especially described in detail in US 3832449.

SSZ-25 is described in US 4954325.

PSH-3 described in US 4 is entrusted to mix the zeolite with another material, which is resistant to heat and other conditions used in the process according to this invention. Such materials include active and inactive compounds, both synthetic and natural zeolites as well as inorganic materials such as clays, silica and/or metal oxides such as aluminum oxide. The inorganic material may be of natural origin and is obtained in the form of gelatinous precipitation or gels including mixtures of silica and metal oxides.

The use of the material in combination with the zeolite, for example, by Association with him or by introducing during the synthesis, which in turn is catalytically active may change the conversion and/or selectivity of the catalytic composition. Inert materials respectively serve as diluents to control the amount of the conversion so that the products of the process transaminirovania could be obtained economically and properly without the use of other means of controlling the reaction rate. These catalytically active or inert materials may be included in, for example, natural clays, such as bentonite and kaolin, to improve copatible catalytic composition good resistance to crushing, as for commercial use, it is desirable to prevent the destruction of the catalytic composition to convert it into a powdery material.

Natural clay that can be mixed with the zeolite, as described in the present invention, as a binder component of the catalytic composition include the montmorillonite and family kaolin, which includes potentiality, and the kaolins commonly known as Dixie, Macname (McNamee), GA (Georgia) and (Florida) Florida clays or others in which the main mineral constituent is aluminum silicate, kaolinite, tiskita (dickite), acritum or anoxia (anauxite). Such clays can be used in raw form after direct extraction or initially subjected to calcination, acid treatment or chemical modification.

In addition to the listed materials, the zeolite may be mixed with a porous matrix binder, such as inorganic oxide selected from the group consisting of silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, thorium oxide, beryllium oxide, magnesium oxide and mixtures thereof such as silica - alumina, silica - magnesia, silica - oxide CGE as ternary compositions of the type silica - aluminum oxide - thorium oxide, silica - alumina - Zirconia, silica - alumina - magnesia and silica - magnesia - Zirconia. Can also be advantageous to ensure the presence of at least part of the above porous matrix binder in the colloidal form in order to facilitate the pressing of the catalytic composition.

The zeolite is usually mixed with a binder or matrix material so that the final composition of the catalytic composition contains a binder or matrix material in a quantity in the range of 5 to 90 wt.% and preferably from 10 to 60 wt.%.

The zeolite of the first catalyst composition is used in combination with at least one hydrogenation component, such as a metal selected from Group VIII of the Periodic table of Elements (CAS version, 1979). Specific examples of components used for hydrogenation include iron, ruthenium, osmium, Nickel, cobalt, rhodium, iridium, or a noble metal type platinum or palladium.

The amount of hydrogenation component is chosen according to the balance between hydrogenosomes activity and functional catalytic metals, as platinum, which are more active than palladium, which does not have such a strong hydrogenosome activity. Typically use less than 10 wt.% and often not more than 1 wt.%.

Component hydrogenation can be included in the first catalytic composition with joint crystallization entered by sharing in the composition of the catalytic composition with an element of Group IIIA, such as aluminum, which is located in the structure, impregnated or mixed with zeolite and a binder component. Such component can be impregnated in or on the zeolite, for example in the case of platinum, treating the zeolite with a solution containing a metal ion of platinum. Suitable platinum compounds for impregnation (impregnation) of the platinum catalyst include hexachloroplatinic acid, douglastown platinum and various compounds containing aminobutanoic complex such as Pt(MH3)4Cl2H2O. Alternative connection hydrogenation component may be added to the zeolite when it is mixed with a binder component, or after the zeolite and the binder component will form into particles by extrusion or granulation.

After processing component hydrogenise the equipment 110 - 143o(230 - 290oF) at least 1 minute and generally not more than 24 hours, at a pressure of 0 - 0.1 MPa (0 - 15 lbs/inch2). After that, the catalytic composition is calcined in a stream of dry gas, such as air or nitrogen, at 260 - 649o(500 - 1200oF) for 1 to 20 hours, the Calcination is preferably carried out at pressures of 0.1 to 0.21 MPa (15 to 30 lb/inch2).

Before the use may be conducted by treatment of the catalyst by steam in order to minimize aromatic hydrogenosomal the catalytic activity of the composition in the ratio of aromatics. During steam treatment of the catalytic composition is usually in contact with 5 - 100% steam, at least 260 - 649o(500 - 1200oF) for at least 1 h, specifically within 1 to 20 hours, at a pressure 0,098 of $ 2.53 MPa (14 - 360 lb/in2).

The second catalytic composition

The second catalytic composition in accordance with the present invention includes a zeolite with an average size of pores having an index of permeability 3 - 12, the ratio of silica to alumina of at least 5. The zeolite, which is especially used, include ZSM-5, which is described in US 3702886, or proton or hydrogen form, and have the political connections7within a relatively short contact time of 1 min or more and preferably 2 minutes or more.

The second zeolite catalyst composition may be mixed with a porous matrix binder, such as inorganic oxide selected from the group consisting of silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, thorium oxide, beryllium oxide, magnesium oxide and mixtures thereof such as silica - alumina, silica - magnesia, silica - Zirconia, silica - oxide of thorium, silicon dioxide - oxides of beryllium, silicon dioxide - titanium dioxide, as well as ternary compositions of type silicon dioxide - aluminum oxide - thorium oxide, silica - alumina - Zirconia, silica - alumina - magnesia and silica - magnesia - Zirconia. Can also be advantageous to ensure the presence of at least part of the above porous matrix binder in the colloidal form in order to facilitate the pressing of the catalytic composition.

The zeolite is usually mixed with a binder or matrix material so that the final composition of the catalytic composition oderifera catalytic composition may be 1 - 20 wt.% and preferably 10 to 15 wt.% calculated on the total weight of the first and second catalytic compositions in the area of reactor transaminirovania. For example, the second catalytic composition may be replaced by a portion of the first catalytic composition at the bottom of the reactor, the first catalytic composition is in the first catalytic layer and the second catalyst composition is in the second catalytic layer in the same reactor. Alternative first catalytic composition may be present in the first reactor and the second catalytic composition may be present in the second reactor.

Raw material

WITH9+ aromatic hydrocarbons used in this process, typically include one or more aromatic compounds containing at least 9 carbon atoms, such as trimethylbenzene, dimethylbenzene, diethylbenzene, etc. WITH Specific9+ aromatic hydrocarbons include mesitylene (1,3,5-trimethylbenzene), durene (1,2,4,5-tetramethylbenzene), hemimellitene (1,2,3-trimethylbenzene), pseudotumor (1,2,4-trimethylbenzene), 1,2-methylethylbenzene, 1,3-methylethylbenzene, 1,4-methylethylbenzene, propylsilane benzenes, butylsilane benzenes, isomers of dimethylethylbenzene etc.

The source of the toluene may be setup for the extraction of aromatic hydrocarbons or any other commercial source.

Usually commodity flow fed into the reaction zone of transaminirovania includes C9+ aromatic hydrocarbons and toluene. Commodity flow may also include a return/unreacted toluene and9+ aromatic hydrocarbons obtained by distillation, leaving the product immediately after transaminirovania. Typically, the toluene is 40 to 90% and preferably 50 to 70% of the total mass of the incoming stream. WITH9+ aromatic plavanie.

The process of hydrocarbon conversion

The process can be carried out in any appropriate reactor, including a reactor having a radial flow fixed bed, continuous downward flow or fluidized bed reactor. Transalkylation usually conducted in the range of 343 - 510o(650 - 950oF) and preferably 399 - 455o(750 - 850oF), a pressure of 0.7 to 4.2 MPa (100 - 600 lb/in2and preferably 1.4 to 3.5 MPa (200 to 500 lb/in2), at a molar ratio of hydrogen to hydrocarbon of from 1 to 5 and preferably from 1 to 3. The speed of transmission over the first catalytic composition lies in the range 1 - 7 WHSV (volumetric rate - the amount of oil per unit weight of catalyst per hour and preferably 2,5 - 4,5 WHSV, and the speed of transmission over a second catalytic composition lies in the range 5 - 100 WHSV, and preferably 15 to 35 WHSV. Reaction conditions of transaminirovania suitable for the conversion of heavy aromatics in the product containing substantial amounts6-C8aromatic compounds such as benzene, toluene and xylenes, particularly benzene and xylene.

Referring to the drawing, you can see that it depicts a simplified diagram technological protector 12, which contains the first and second catalytic composition. In the reactor are maintained conditions sufficient to toluene and methylsiloxane aromatic hydrocarbons (toluene, xylenes, trimethylbenzene and tetramethylbenzene) has reached thermodynamic equilibrium as the result of transaminirovania. The product from reactor 12 are removed through line 14 and introduced into the hydrogen separator 16, which separates the hydrogen for recycle to the reactor 12 through line 18. The thread then passes through line 20 to the section of the stabilizer 22 which removes C5fuel gas known methods. After that, the product is subjected to fractionation on the threads of benzene, toluene and xylenes in distillation columns 24, 26 and 28, respectively, to separate these flows. The remaining product containing unreacted9+ source and any heavy aromatic hydrocarbons, is separated into two streams - stream aromatic hydrocarbons9+ (stream 30) and the stream WITH a10+ aromatic hydrocarbons (stream 29). Thread 30 recyclist in the original reaction stream removed from the process, or do a combination of both (partial recycling). Thread 2910+ aromatic hydrocarbons suitable as an additive to gasoline aluminia diluted with the help of Victor and loaded into the reactor, having an outer diameter of 9.5 mm (3/8 inch), and then dried in a stream of nitrogen at 399o(750oF). Then the flow of nitrogen is replaced by a flow of hydrogen and the product obtained by passing a mixture WITH9+ aromatic hydrocarbons, toluene and hydrogen over a first zeolite catalyst having an index of permeability of 0.5 - 3, which was introduced into the reactor at various flow rates, while maintaining the molar ratio of hydrogen to hydrocarbon as 3/1 and pressure of 2.46 MPa (350 lb/in2).

Data gas chromatographic analysis coming out of the reactor flow using columns petrocol, 150 m with hydrogen as carrier gas, and standardized data for key components are listed in the table. 1. The purity of the distilled benzene calculated based on the standardized data, using mass factors developed based on simulated distillation using software ProvisionTMfrom Simulation Sciences according to the following equation,

The purity of distilled benzene = 100 x Benzene/Benzene+a+b+C+d)

where

a = 0.1 s6-paraffins,

b = 0.7 Methylcyclopentane,

C = Cyclohexane,

d = C7naphthenes (dimethylcyclopentane, metals and the pressure of 2.46 MPa (750oF, 350 lb/in2) purity benzene increases with lower WHSV due to increased conversion of non-aromatic components. The decrease in conversion Methylcyclopentane and methylcyclohexane with increasing WHSV increases pollution distilled benzene. However, the purity of the distilled benzene rises to the level of 99.85% even when the WHSV value equal to 29. At the same time the increase of temperature leads to a significant improvement of the purity of the distilled benzene compared to the improvement achieved by reducing the concentrations of these methylnaphtho. In addition, the concentration of cyclohexane decreases sharply with increasing temperature.

1. The method of conversion of hydrocarbons containing FROM9+ aromatic hydrocarbons to lighter aromatic compounds, which consists in the interaction (i)9+ aromatic hydrocarbons and (ii) toluene or benzene in the presence of hydrogen under the reaction conditions of transaminirovania over the first catalyst composition comprising a zeolite having an index of permeability of 0.5 - 3, and a hydrogenation component, wherein the product transaminirovania in contact with the second catalytic composition comprising CEO the Oia at least 5, obtaining the reaction product of transaminirovania containing (i) benzene, or toluene, and (ii) xylene.

2. A method of producing benzene, which consists in (a) interaction (i)9+ aromatic hydrocarbons and (ii) toluene or benzene in the presence of hydrogen under the reaction conditions of transaminirovania over the first catalyst composition comprising a zeolite having an index of permeability of 0.5 - 3, and a hydrogenation component, wherein the product transaminirovania contact with the second catalyst composition comprising a zeolite with an average size of pores having an index of permeability 3 - 12, the ratio of silica to alumina of at least 5, with the receipt of the product stream containing (i) benzene, or toluene, and (ii) xylene, and (b) distilled benzene or toluene from the specified stream product transaminirovania to obtain a product of benzene or toluene with increased purity.

3. The method according to p. 2, characterized in that the benzene - product of stage (b) has a purity of at least 99,85%.

4. The method according to p. 3, characterized in that the benzene - product of stage (b) has a purity of at least 99,85% without the need for additional phase extraction.

5. The method according to p. 1, Aty least one metal, selected from group VIII of the Periodic table of elements, and zeolite first catalyst composition selected from the group consisting of MCM-22, SH-3, SSZ-25, ZSM-12, and zeolite beta.

6. The method according to p. 5, characterized in that the zeolite of the second catalytic composition is a zeolite ZSM-5.

7. The method according to p. 1, characterized in that the conditions of the reaction transaminirovania include a temperature in the range of 343 - 510oWith pressure in the range of 7.0 to 4.2 MPa, and a molar ratio of hydrogen to hydrocarbon in the range of 1 to 5.

 

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