JP2015182999A - Method for producing xylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing xylene with high yield even though a catalytically cracked gasoline, which has a low aromatic hydrocarbon content ratio and contains an unsaturated hydrocarbon, a sulfur content, and a nitrogen content, is used as a starting material for a conversion reaction such as a disproportionation reaction or a transalkylation reaction.SOLUTION: A method for producing xylene comprises: (a) a fractional distillation step for conducting fractional distillation to obtain a distillate fraction having a boiling point range of 145 to 205°C by subjecting a fluid catalytically cracked gasoline to distillation; (b) a hydrogenation step for adjusting the sulfur content to 0 to 6 ppm by mass and the nitrogen content to 0 to 6 ppm by mass by subjecting the distillate fraction obtained in the fractional distillation step (a) and having the boiling point range of 145 to 205°C to a hydrodesulfurization/denitrification reaction; and (c) a disproportionation/transalkylation step for subjecting a product oil obtained in the hydrogenation step (b) and containing an aromatic hydrocarbon to a disproportionation reaction or a transalkylation reaction.

Description

  The present invention relates to a method for producing xylene.

  Xylene is an important compound as a starting material for producing various important industrial chemicals such as phthalic acid (terephthalic acid, isophthalic acid, orthophthalic acid) which is a raw material for polyester.

As a method for producing xylene, there is usually a method of extracting and fractionating naphtha after reforming with a catalytic reformer, or a method of extracting and fractionating cracked gasoline by-produced by thermal decomposition of naphtha. Are known.
In addition, conventionally, a method for producing other aromatic hydrocarbons having different carbon numbers using an aromatic hydrocarbon as a raw material has been attempted (see, for example, Patent Document 1 (Japanese Patent Laid-Open No. 60-246330)), As a method for producing xylene, a production method using a transalkylation reaction or a disproportionation reaction of aromatic hydrocarbons in which aromatic hydrocarbons are reacted with each other to convert them into aromatic hydrocarbons having different carbon numbers can be considered.

JP-A-60-246330

The transalkylation reaction is a method in which a plurality of aromatic hydrocarbons having different carbon numbers are reacted to convert them into the target aromatic hydrocarbon, and the disproportionation reaction of aromatic hydrocarbons is the same for two molecules. This is a method in which an aromatic hydrocarbon reacts and is converted into a target aromatic hydrocarbon.
For example, as a method for producing xylene using a disproportionation reaction of an aromatic hydrocarbon, a method of producing benzene and xylene by a disproportionation reaction of toluene can be exemplified, and an aromatic having 9 or more carbon atoms is used as a raw material. A method of increasing the yield of xylene by adding a group hydrocarbon to cause a transalkylation reaction is also conceivable.

  When xylene is industrially produced by transalkylation reaction or disproportionation reaction, usually heavy naphtha obtained by atmospheric distillation of crude oil is further reformed by catalytic reforming using a catalytic reformer. A heavy catalytic reformed gasoline rich in aromatic components, obtained by refinement, is used.

On the other hand, since the oil fraction is a co-product, there is a limit to the amount of heavy naphtha obtained by refining a certain amount of crude oil.
Since heavy naphtha is also used as an industrial raw material other than xylene, in the industrial production of xylene, the oil fraction other than heavy naphtha is effectively utilized to diversify the raw material and reduce the production cost. Reduction is required.

  Examples of petroleum fractions containing aromatic components include fluid catalytic cracking gasoline obtained from fluid catalytic cracking equipment, but fluid catalytic cracking gasoline contains aromatic hydrocarbons compared to heavy catalytic reformed gasoline. It is not suitable as an industrial raw material for xylene because it contains a low proportion of unsaturated hydrocarbons that are highly reactive and contains sulfur (sulfur compounds), nitrogen (nitrogen compounds), etc. that degrade the catalyst. .

Under such circumstances, the present invention has a low content ratio of aromatic hydrocarbons, and conversion of catalytic cracked gasoline containing unsaturated hydrocarbons, sulfur, nitrogen, etc., such as disproportionation reaction or transalkylation reaction, etc. An object of the present invention is to provide a method for producing xylene in a simple and high yield while being used as a raw material for the reaction.

  In order to solve the above technical problem, the present inventors have conducted intensive studies.As a result, (a) a fractionation step in which a fluid catalytic cracking gasoline is distilled to fractionate a fraction having a boiling range of 145 to 205 ° C .; (B) The hydrous desulfurization / denitrification reaction is performed on the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step (a), so that the sulfur content is 0 to 6 ppm by mass and the nitrogen content is reduced. A hydrotreating step adjusted to 0 to 6 ppm by mass, and (c) a disproportionation reaction or a transalkylation reaction is performed on the product oil containing the aromatic hydrocarbon obtained in the above (b) hydrotreating step. It has been found that the above technical problem can be solved by a method for producing xylene including a disproportionation / transalkylation step, and the present invention has been completed based on this finding.

That is, the present invention
(1) A method for producing xylene,
(A) a fractionation step of subjecting fluid catalytic cracking gasoline to distillation to fractionate a fraction having a boiling range of 145 to 205 ° C;
(B) The hydrous desulfurization / denitrification reaction is performed on the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step (a), so that the sulfur content is 0 to 6 ppm by mass and the nitrogen content is reduced. A hydrotreatment step of adjusting to 0 to 6 ppm by mass;
(C) including a disproportionation / transalkylation step in which a disproportionation reaction or a transalkylation reaction is performed on the product oil containing the aromatic hydrocarbon obtained in the above (b) hydrotreating step. A method for producing xylene,
(2) The fraction having a boiling range of 145 to 205 ° C. obtained in the (a) fractionation step comprises 25 to 45% by volume of aromatic hydrocarbons having 9 to 9 carbon atoms and 10 hydrocarbons having 10 to 10 carbon atoms. The method for producing xylene according to the above (1), comprising 15 to 25% by volume,
(3) The method for producing xylene according to (1) or (2) above, wherein the (b) hydrotreating step is a step of further separating non-aromatic hydrocarbons after the hydrodesulfurization / denitrification reaction. To do.

  According to the present invention, the catalytic cracking gasoline containing a low content of aromatic hydrocarbons and containing unsaturated hydrocarbons, sulfur, nitrogen, etc. is used as a raw material for conversion reaction such as disproportionation reaction or transalkylation reaction. While being used, it is possible to provide a method for producing xylene in a simple and high yield.

The method for producing xylene according to the present invention includes:
(A) a fractionation step of subjecting fluid catalytic cracking gasoline to distillation to fractionate a fraction having a boiling range of 145 to 205 ° C;
(B) The hydrous desulfurization / denitrification reaction is performed on the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step (a), so that the sulfur content is 0 to 6 ppm by mass and the nitrogen content is reduced. A hydrotreatment step of adjusting to 0 to 6 ppm by mass;
(C) including a disproportionation / transalkylation step in which a disproportionation reaction or a transalkylation reaction is performed on the product oil containing the aromatic hydrocarbon obtained in the above (b) hydrotreating step. It is what.

<(A) Fractionation process>
In the method for producing xylene according to the present invention, fluid catalytic cracking gasoline (FCC gasoline) distilled from a fluid catalytic cracking device (FCC) is used as a raw material oil.

  The fluid catalytic cracking apparatus is for producing fluid catalytic cracking gasoline from heavy hydrocarbons by fluid catalytic cracking process (FCC process), where the fluid catalytic cracking process is a fluidized catalyst and hydrocarbon oil. Is a process for obtaining gasoline, middle distillate, etc.

  Examples of fluid catalytic cracking processes include, for example, HYDROCARBON PROCESSING / NOVEMBER 2000, pages 107 to 110, ABB Lummus Global Inc. ya, Kellogg Brown & Roots, Inc. And Shell Global Solutions International B. V. Also, Stone & Webster Inc. , A Shaw Group Co. / Institut Francais du Petrole. And UOP LLC. The process proposed by various process manufacturers can be listed.

  In order to obtain the above fluid catalytic cracking gasoline, a relatively heavy hydrocarbon oil (hydrocarbon mixture) boiling above the boiling point of gasoline is converted to a so-called solid acid such as zeolite, silica alumina, and alumina by a fluid catalytic cracking process. What is necessary is just to make it contact with the catalyst shown at high temperature.

  In a fluid catalytic cracking process on a commercial scale, a fluid catalytic cracking catalyst having a solid acidity is usually continuously added to a fluid catalytic cracking apparatus composed of two types of containers, a vertically installed cracking reactor and a catalyst regenerator. It can be done by circulating it.

That is, the fluid catalytic cracking catalyst deactivated by the coke deposited on the surface as a result of being subjected to the treatment of hydrocarbon oil (hydrocarbon mixture) in the cracking reactor is separated from the cracked products (various product oils), After stripping, transfer to the catalyst regenerator, mix the hot regenerated catalyst regenerated in the catalyst regenerator with the hydrocarbon oil to be cracked again, and circulate through the cracking reactor in the upward direction. The reaction can be carried out continuously and the resulting cracked product is distilled off into one or more fractions such as dry gas, LPG, gasoline fraction, LCO and HCO or slurry oil. Further, the decomposition reaction may be further advanced by recirculating part or all of the decomposition product into the cracking reactor.
In the method for producing xylene according to the present invention, a gasoline fraction is used as fluid catalytic cracking gasoline among the fractions separated from the cracked product.

The hydrocarbon oil (hydrocarbon mixture) used in the catalytic cracking reaction in the fluid catalytic cracking process is a relatively heavy hydrocarbon mixture that boils above the boiling range of gasoline, specifically, atmospheric distillation of crude oil. Or gas oil fraction obtained by vacuum distillation, atmospheric distillation residue oil and vacuum distillation residue oil, etc. can be mentioned, such as coker light oil, solvent desulfurization oil, solvent desulfurization asphalt, tar sand oil, shale oil oil, coal liquefaction Oil etc. may be sufficient.
Further, as the hydrocarbon oil (hydrocarbon mixture) to be used in the fluid catalytic cracking process, a hydrotreatment well known to those skilled in the art, that is, a Ni—Mo catalyst, a Co—Mo catalyst, a Ni—Co—Mo catalyst. In addition, hydrotreated oil hydrodesulfurized at high temperature and high pressure in the presence of a hydrotreating catalyst such as a Ni-W catalyst may also be mentioned.

The operating conditions of the cracking reactor for obtaining fluid catalytic cracking gasoline used in the present invention are preferably a reaction temperature of 400 to 600 ° C., more preferably 450 to 550 ° C., and a reaction pressure of preferably normal pressure to 5 kg / cm ^3, more preferably from normal pressure ~3kg / cm ^3, the mass ratio of preferably 2 to 20, "fluid catalytic cracking catalyst / feedstock to become hydrocarbon oil" represented by, more preferably 4 to 15 It is.

When the reaction temperature is within the above range, fluid catalytic cracking gasoline containing a predetermined amount of aromatic hydrocarbon can be efficiently obtained. When the said reaction temperature is less than 400 degreeC, progress of the decomposition reaction of hydrocarbon oil becomes slow, and since the amount of decomposition products falls, it becomes difficult to perform economical driving | operation. Moreover, when the said reaction temperature is over 600 degreeC, it will become easy to produce | generate a large amount of olefin components, and the content rate of the aromatic hydrocarbon in the fluid catalytic cracking gasoline obtained will become easy to fall.
Moreover, when the reaction pressure is within the above range, the decomposition reaction in which the number of moles can be increased, and when the reaction pressure exceeds 5 kg / cm ³ , the decomposition reaction is difficult to proceed. Become.
Furthermore, when the mass ratio represented by “fluid catalytic cracking catalyst / raw hydrocarbon oil as raw material” is within the above range, fluid catalytic cracking gasoline can be obtained efficiently. When the mass ratio is less than 2, the catalyst concentration in the cracking reactor becomes too low, and it becomes difficult for the hydrocarbon oil used as a raw material to decompose. Moreover, when the said mass ratio is more than 20, the decomposition effect by the raise of a catalyst concentration will be saturated, and it will become uneconomical.

  In the method for producing xylene of the present invention, the fluid catalytic cracking gasoline is not particularly limited as long as it contains a fraction having a boiling range of 145 to 205 ° C, and the boiling range is 30 to 240 ° C. Preferably, the temperature is 33 to 235 ° C, more preferably the boiling range is 35 to 220 ° C.

In the xylene production method of the present invention, in the (a) fractionation step, fluid catalytic cracking gasoline is subjected to distillation treatment to fractionate a fraction having a boiling range of 145 to 205 ° C.
(A) The fraction distilled in the fractionation step has a boiling range of 145 to 205 ° C, preferably 147 to 202 ° C, more preferably 150 to 200 ° C.
In the method for producing xylene of the present invention, (a) the boiling range of the fraction obtained in the fractionation step is within the above range, thereby containing a predetermined amount of aromatic hydrocarbons as a raw material for xylene and hydrogen to be described later Degradation of the reaction catalyst due to coke formation can be suppressed during the chemical treatment reaction, the disproportionation reaction or the transalkylation reaction.

In the method for producing xylene of the present invention, (a) the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step preferably contains 25 to 45% by volume of an aromatic hydrocarbon having 9 carbon atoms. 28 to 42% by volume is more preferable, and 30 to 40% by volume is more preferable.
In the xylene production method of the present invention, (a) the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step contains 15 to 25% by volume of C10 aromatic hydrocarbons. Is preferable, more preferably 17 to 23% by volume, and even more preferably 19 to 21% by volume.

  In the method for producing xylene of the present invention, (a) the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step contains the above-mentioned ratio of the aromatic hydrocarbon having 9 carbon atoms and the aromatic hydrocarbon having 10 carbon atoms. In this case, xylene can be efficiently produced by a disproportionation reaction or a transalkylation reaction described later.

In the present application documents, examples of the aromatic hydrocarbon having 9 carbon atoms include trimethylbenzene and methylethylbenzene, and examples of the aromatic hydrocarbon having 10 carbon atoms include dimethylethylbenzene and tetramethylbenzene. it can.
In addition, in this application document, the content rate of a C9 aromatic hydrocarbon and the content rate of a C10 aromatic hydrocarbon mean the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, (a) the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step preferably contains 48 to 57% by volume of aromatic hydrocarbons in total. The content is more preferably 50 to 57% by volume, and further preferably 52 to 57% by volume.
In addition, in this application document, the content rate of an aromatic hydrocarbon means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, (a) the fraction having a boiling point range of 145 to 205 ° C. obtained in the fractionation step is preferably such that the content of saturated hydrocarbon is 0 to 40% by volume, What is -35 volume% is more preferable, and what is 0-30 volume% is still more preferable.
When the content ratio of the saturated hydrocarbon is within the above range, the content ratio of the aromatic hydrocarbon that is the raw material for xylene can be easily controlled within a predetermined range.
In addition, in this application document, the content rate of a saturated hydrocarbon means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, (a) the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step has an unsaturated hydrocarbon (olefin) content of 0 to 15% by volume. Are preferred, those with 0-13 volume% are more preferred, and those with 0-11 volume% are even more preferred.
In the hydrodesulfurization / denitrification reaction to be described later, the reactivity of the unsaturated hydrocarbon is within the above range, so that the reactivity of the reaction can be lowered, and excessive hydrogenation of aromatic hydrocarbons can be suppressed. it can.
In addition, in this application document, the content rate of unsaturated hydrocarbon (olefin) means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, (a) the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step preferably has a sulfur content of 30 mass ppm or less, and is 20 mass ppm or less. Some are more preferable, and what is 10 mass ppm or less is still more preferable. In addition, in the fraction whose boiling point range obtained by (a) fractionation process is 145-205 degreeC, sulfur content is 2 mass ppm or more normally.
When the sulfur content is not more than the above numerical value, the severity of the reaction can be lowered in the hydrodesulfurization / denitrification step described later, and excessive hydrogenation of aromatic hydrocarbons can be suppressed.
In addition, in this application document, sulfur content means the value measured according to JISK2541.

In the method for producing xylene of the present invention, (a) a fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step preferably has a nitrogen content of 10 mass ppm or less, and is 5 mass ppm or less. Some are more preferable, and what is 3 mass ppm or less is still more preferable. In addition, in the fraction whose boiling point range obtained by (a) fractionation process is 145-205 degreeC, nitrogen content is 2 mass ppm or more normally.
When the nitrogen content is not more than the above numerical value, the severity of the reaction can be lowered in the hydrodesulfurization / denitrification step described later, and excessive hydrogenation of aromatic hydrocarbons can be suppressed.
In addition, in this application document, nitrogen content means the value measured according to JISK2609.

  In the method for producing xylene of the present invention, the embodiment of the (a) fractionation step is not particularly limited as long as it is a method capable of obtaining a fraction having a boiling range of 145 to 205 ° C., and a known fractionation method. It can be performed by applying.

<(B) Hydrogenation process>
In the method for producing xylene of the present invention, in the (b) hydrotreating step, the fraction having a boiling range of 145 to 205 ° C. obtained in the above (a) fractionation step is subjected to hydrodesulfurization / denitrification reaction. To adjust the sulfur content to 0-6 mass ppm and the nitrogen content to 0-6 mass ppm.

  In the method for producing xylene of the present invention, the hydrodesulfurization / denitrification treatment can be performed using a known technique, for example, using the hydrodesulfurization catalyst generally used in petroleum refining, the above (a) Examples thereof include a method in which a fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step is reacted under high temperature and high pressure reaction conditions to perform desulfurization and denitrogenation treatment.

Examples of the hydrodesulfurization catalyst include a catalyst in which an active metal having a hydrogenation function is supported on an inorganic oxide support.
Examples of the inorganic oxide carrier include one or more selected from various porous inorganic oxides such as alumina, silica, titania, magnesia, silica-alumina, and silica or silica-alumina is preferable.
Examples of the active metal include one or more selected from Group VI metals such as molybdenum and tungsten, and Group VIII metals such as nickel and cobalt. For example, a combination of metals such as Ni—Mo or Co—Mo may be used. preferable.

The conditions for hydrotreating depend on the content of sulfur, nitrogen and unsaturated hydrocarbon (olefin) contained in the fraction having a boiling range of 145 to 205 ° C. obtained in the above (a) fractionation step. The reaction temperature is usually 200 to 500 ° C., the hydrogen partial pressure is 0.5 to 10 MPa, the liquid space velocity (LHSV) is 1.0 to 20 hr ⁻¹ , and the hydrogen oil ratio. Is set within the range of 100 to 1000 NL / L.
In the xylene production method of the present invention, (b) in the hydrodesulfurization / denitrification reaction in the hydrotreating step, if the hydrogenation reaction conditions are severe, desulfurization efficiency or denitrification efficiency is improved, but aromatic carbonization Since hydrogen is also hydrogenated and converted to a cyclic saturated hydrocarbon, it is preferable to carry out the hydrogenation reaction under relatively mild conditions.

  In the method for producing xylene of the present invention, (b) the hydrodesulfurization / denitrification reaction in the hydrotreating step reduces the sulfur content and the nitrogen content in the resulting hydrotreated oil. At the same time, the content of unsaturated hydrocarbons (olefins) unnecessary for xylene production can be reduced.

The xylene production method of the present invention adjusts the sulfur content in the hydrotreated oil to 0 to 6 mass ppm by hydrodesulfurization / denitrification reaction in (b) hydrotreating step. Yes, it is preferable to adjust to 0-4 mass ppm, and it is more preferable to adjust to 0-2 mass ppm.
In the method for producing xylene of the present invention, the nitrogen content in the hydrotreated oil is adjusted to 0-6 mass ppm by hydrodesulfurization / denitrification reaction in (b) hydrotreating step. It is preferable to adjust so that it may become 0-4 mass ppm, and it is more preferable to adjust so that it may become 0-2 mass ppm.
Furthermore, in the method for producing xylene of the present invention, the content ratio of unsaturated hydrocarbon (olefin) in the hydrotreated oil is determined by hydrodesulfurization / denitrification reaction in (b) hydrotreating step. It is preferable to adjust so that it may become 0-5 volume%, it is preferable to adjust so that it may become 0-3 volume%, and it is more preferable to adjust so that it may become 0-1 volume%.
In the method for producing xylene of the present invention, (a) when the boiling point range obtained in the fractionation step is 145 to 205 ° C., the sulfur content and the nitrogen content are each over 6 mass ppm. (B) Each content can be reduced to a predetermined amount by the hydrotreating step, and (a) the sulfur content in the fraction having a boiling point range of 145 to 205 ° C. obtained in the fractionation step is In the case of 6 mass ppm or less, each content can be further reduced by the (b) hydrotreatment process.

  In the method for producing xylene of the present invention, the sulfur content in the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction in the hydrotreating step (b) is a value measured according to JIS K2541. The nitrogen content in the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction means a value measured according to JIS K 2609, and is obtained by hydrodesulfurization / denitrification reaction. The content ratio of the unsaturated hydrocarbon (olefin) in the hydrotreated oil is a value measured according to JIS K 2536-2.

Sulfur compounds and nitrogen compounds in hydrotreated oils may become poisonous substances that degrade the performance of the active metal that constitutes the reaction catalyst during the disproportionation reaction or transalkylation reaction described below, and are also unsaturated. Since hydrocarbons (olefins) may be polymerized to precipitate coke, any of them becomes a causative substance that reduces the life of the reaction catalyst during the disproportionation reaction or transalkylation reaction.
When the sulfur content, nitrogen content, and unsaturated hydrocarbon (olefin) content in the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction are within the above ranges, disproportionation reaction or transalkyl Xylene can be efficiently produced while suppressing a decrease in the lifetime of the reaction catalyst during the conversion reaction.

In the method for producing xylene of the present invention, the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction in the hydrotreating step (b) has a saturated hydrocarbon content of 39 to 51% by volume. It is preferable that it is 41-49 volume%, and it is further more preferable that it is 43-47 volume%.
The hydrotreated oil obtained by the hydrodesulfurization / denitrification reaction has a saturated hydrocarbon content in the above range, so that xylene can be efficiently used in the disproportionation reaction or transalkylation reaction described later. Can be obtained.
In addition, in this application document, the content rate of the said saturated hydrocarbon means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, (b) the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction in the hydrotreating step is a total of 45 to 60% by volume of aromatic hydrocarbons. It is preferable that it is contained, more preferably 48 to 58% by volume, and still more preferably 51 to 56% by volume.
In addition, in this application document, the content rate of an aromatic hydrocarbon means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction in the hydrotreating step (b) has a content ratio of 9-carbon aromatic hydrocarbons. It is preferably 26 to 40% by volume, more preferably 28 to 39% by volume, and further preferably 30 to 38% by volume.
In the xylene production method of the present invention, the hydrotreated oil obtained by the hydrodesulfurization / denitrification reaction in the (b) hydrotreating step is a content ratio of C10 aromatic hydrocarbons. Is preferably 15 to 26% by volume, more preferably 16 to 24% by volume, and even more preferably 17 to 22% by volume.
In the method for producing xylene of the present invention, the content ratio of the aromatic hydrocarbon having 9 carbon atoms and the content ratio of the aromatic hydrocarbon having 10 carbon atoms in the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction Is within the above range, the disproportionation reaction or transalkylation reaction described later can be carried out efficiently.
In addition, in this application document, the content rate of the said C9 aromatic hydrocarbon and the content rate of a C10 aromatic hydrocarbon mean the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, the hydrotreated oil obtained by the hydrodesulfurization / denitrification reaction in the (b) hydrotreating step is a normal propylbenzene, which is an aromatic hydrocarbon having 9 carbon atoms. The content ratio is preferably 0 to 5% by volume, more preferably 0 to 4% by volume, and further preferably 0 to 3% by volume.
Further, in the xylene production method of the present invention, the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction in the hydrotreating step (b) is trimethylbenzene, which is an aromatic hydrocarbon having 9 carbon atoms. Is preferably 12 to 20% by volume, more preferably 13 to 19% by volume, and still more preferably 14 to 18% by volume.

In the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction, when the content ratio of normal propylbenzene, which is an aromatic hydrocarbon having 9 carbon atoms, is within the above range, saturated hydrocarbons by dealkylation reaction are obtained. Generation can be suppressed.
Further, in the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction, the content ratio of trimethylbenzene, which is an aromatic hydrocarbon having 9 carbon atoms, is within the above range. Xylene can be efficiently obtained in the reaction or transalkylation reaction.
In addition, in this application document, the content rate of the said normal propylbenzene and trimethylbenzene means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, a desulfurization / denitrification reaction may be further performed as a separate pretreatment before the (a) fractionation step.
In this case, the fluid catalytic cracking gasoline whole fraction distilled from the fluid catalytic cracking device is directly desulfurized / denitrogenated and then (a) distilled to fractionate a fraction having a boiling range of 145 to 205 ° C. Embodiments can be mentioned.

  In the method for producing xylene of the present invention, (b) the hydrotreated oil obtained by hydrodesulfurization / denitrification reaction in the hydrotreating step is directly used as a product oil containing aromatic hydrocarbons. It can be subjected to a conversion / transalkylation step.

  In the method for producing xylene of the present invention, the above-mentioned (b) hydrotreating step further separates non-aromatic hydrocarbons (hydrocarbons other than aromatic hydrocarbons) after hydrodesulfurization / denitrification reaction. It may be.

The separation treatment of the non-aromatic hydrocarbon is preferably performed by distilling or extracting the hydrotreated oil obtained by the hydrodesulfurization / denitrification reaction.
Specific examples of the method for separating the aromatic hydrocarbon from the hydrotreated oil include a liquid-liquid extraction method and an extractive distillation method. Examples of the selective solvent used in the liquid-liquid extraction method include one or more selected from glycerol and sulfolane derivatives.

The liquid-liquid extraction method separates and recovers polar hydrocarbons from a hydrocarbon mixture containing polar and nonpolar hydrocarbons, as described, for example, in US Pat. No. 4,058,454. In the method for producing xylene of the present invention, all aromatic hydrocarbons contained in the hydrotreated oil obtained by the hydrodesulfurization / denitrification reaction are known. Can be implemented using the property that is polar.
That is, when a solvent capable of dissolving a polar substance such as sulfolane is added to the hydrotreated oil obtained by the hydrodesulfurization / denitrification reaction, polar aromatic hydrocarbons are selectively dissolved. Since non-polar non-aromatic hydrocarbons can be separated, non-aromatic hydrocarbons are separated and removed from the hydrotreated oil obtained by the above hydrodesulfurization / denitrification reaction, and high-purity aromatic hydrocarbons are obtained. A product oil containing can be obtained.

In the production method of the xylene production method of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil containing the aromatic hydrocarbon has a sulfur content of 0 to 0. What is 6 mass ppm is preferable, What is 0-4 mass ppm is more preferable, What is 0-2 mass ppm is further more preferable.
In the xylene production method of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil containing the aromatic hydrocarbon has a nitrogen content of 0-6. The mass is preferably ppm, more preferably 0 to 4 ppm by mass, and still more preferably 0 to 2 ppm by mass.
In addition, in this application document, the said sulfur content means the value measured according to JISK2541, and the nitrogen content means the value measured according to JISK2609.

In the method for producing xylene of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil containing the aromatic hydrocarbon has a total amount of aromatic hydrocarbons of 90 to The content is preferably 100% by volume, more preferably 92-100% by volume, and still more preferably 94-100% by volume.
In addition, in this application document, the content rate of an aromatic hydrocarbon means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil containing the aromatic hydrocarbon is a content ratio of the aromatic hydrocarbon having 9 carbon atoms. However, it is preferably 50 to 70% by volume, more preferably 55 to 67% by volume, and still more preferably 60 to 65% by volume.
Further, in the method for producing xylene of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil has a C10 aromatic hydrocarbon content ratio of 30 to 42. What is volume% is preferable, what is 32 to 40 volume% is more preferable, and what is 35 to 38 volume% is more preferable.
In the production method of xylene of the present invention, in a product oil containing aromatic hydrocarbons obtained by separating and removing non-aromatic hydrocarbons, the content ratio of aromatic hydrocarbons having 9 carbon atoms and aromatic carbonization having 10 carbon atoms When the hydrogen content is within the above range, the disproportionation reaction or transalkylation reaction can be carried out efficiently.
In addition, in this application document, the content rate of the said C9 aromatic hydrocarbon and the content rate of a C10 aromatic hydrocarbon mean the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil containing the aromatic hydrocarbon is normal, which is an aromatic hydrocarbon having 9 carbon atoms. The content ratio of propylbenzene is preferably 0 to 9% by volume, more preferably 0 to 7% by volume, and further preferably 0 to 5% by volume.
In the xylene production method of the present invention, when the non-aromatic hydrocarbon is separated in the (b) hydrotreating step, the resulting oil containing the aromatic hydrocarbon is an aromatic hydrocarbon having 9 carbon atoms. The content ratio of a certain trimethylbenzene is preferably 25 to 36% by volume, more preferably 26 to 34% by volume, and further preferably 27 to 32% by volume.

In the method for producing xylene of the present invention, (b) the product oil containing aromatic hydrocarbons obtained by separating non-aromatic hydrocarbons in the hydrotreating step has a normal propylbenzene content ratio within the above range. By being, the production | generation of the saturated hydrocarbon by a dealkylation reaction can be suppressed.
In the method for producing xylene of the present invention, (b) the product oil obtained by separating the non-aromatic hydrocarbons in the hydrotreating step will be described later because the content ratio of trimethylbenzene is within the above range. Xylene can be efficiently obtained in the disproportionation reaction or transalkylation reaction.
In addition, in this application document, the content rate of the said normal propylbenzene and trimethylbenzene means the value measured according to JISK2536-2.

In the method for producing xylene of the present invention, (b) the product oil containing aromatic hydrocarbons obtained by separating non-aromatic hydrocarbons in the hydrotreating step has a saturated hydrocarbon content of 0 to 7 volumes. %, Preferably 0 to 5% by volume, more preferably 0 to 4% by volume.
In the method for producing xylene of the present invention, (b) the product oil obtained by separating the non-aromatic hydrocarbon in the hydrotreating step will be described later because the content ratio of the saturated hydrocarbon is within the above range. Xylene can be efficiently obtained in the disproportionation reaction or transalkylation reaction.
In addition, in this application document, the content rate of the said saturated hydrocarbon means the value measured according to JISK2536-2.

In the xylene production method of the present invention, (b) the product oil containing aromatic hydrocarbons obtained by separating non-aromatic hydrocarbons in the hydrotreating step has an unsaturated hydrocarbon content ratio of 0 to 2. What is volume% is preferable, what is 0 to 1 volume% is more preferable, and what is 0 to 0.5 volume% is more preferable.
In the method for producing xylene of the present invention, (b) the product oil obtained by separating non-aromatic hydrocarbons in the hydrotreating step has an unsaturated hydrocarbon (olefin) content in the above range. Thus, xylene can be efficiently obtained in a disproportionation reaction or a transalkylation reaction described later by suppressing the hydrogen consumption.
In addition, in this application document, the content rate of the said unsaturated hydrocarbon means the value measured according to JISK2536-2.

  The method for producing xylene of the present invention comprises (c) disproportionation / transalkylation by further separating non-aromatic hydrocarbons after hydrodesulfurization / denitrification reaction in the (b) hydrotreating step. The process can be performed efficiently.

<Disproportionation / transalkylation process>
In the method for producing xylene of the present invention, in the (c) disproportionation / transalkylation step, the product oil containing the aromatic hydrocarbon obtained in the above (b) hydrotreating step is subjected to a disproportionation reaction or A transalkylation reaction is performed.

The reaction conditions for the disproportionation reaction or alkylation reaction are not particularly limited as long as xylene can be obtained.
In the disproportionation reaction or transalkylation reaction, (b) the product oil containing the aromatic hydrocarbon obtained in the hydrotreating step has a liquid space velocity (LHSV) of preferably 0.01 h ⁻¹ or more, more preferably 0.1 h ^-1 or more, preferably ^{10h -1} or less, more preferably supplied in ^{5h -1} or less, it is preferable to carried out by contacting the catalyst.

In the disproportionation reaction or transalkylation reaction, the reaction temperature is preferably 200 ° C. or higher, more preferably 230 ° C. or higher, further preferably 260 ° C. or higher, preferably 550 ° C. or lower, more preferably 530 ° C. or lower. Particularly preferably, it is 510 ° C. or lower.
If the reaction temperature is less than 200 ° C., the activation of aromatic hydrocarbons is insufficient, and the active sites are poisoned by the water produced by the reaction, so the conversion rate of aromatic hydrocarbons is low. Easy to be. On the other hand, when the reaction temperature exceeds 550 ° C., in addition to consuming a lot of energy, the catalyst life tends to be shortened.

  In the disproportionation reaction or transalkylation reaction, the reaction pressure is preferably at least atmospheric pressure, more preferably at least 0.1 MPaG, even more preferably at least 0.5 MPaG, preferably at most 10 MPaG, more preferably at most 5 MPaG. .

  Further, when performing the disproportionation reaction or transalkylation reaction, an inert gas such as nitrogen gas or helium gas or hydrogen gas for suppressing coking may be circulated or pressurized in the reaction system. .

The reaction catalyst used in the above disproportionation reaction or transalkylation reaction is not particularly limited as long as it is an aromatic conversion catalyst and causes disproportionation reaction or transalkylation.
The reaction catalyst is preferably one that selectively dealkylates an ethyl group or a propyl group while retaining a methyl group and simultaneously has a transalkylation ability.
Specifically, a shape-selective metallosilicate catalyst is preferable, crystalline aluminosilicate is more preferable, and zeolite is more preferable.
As zeolite, any zeolite selected from mordenite, Y-type zeolite, X-type zeolite, beta-type zeolite, ZSM-5 and the like can be used, but mordenite is preferred.

In the xylene production method of the present invention, (c) in the disproportionation / transalkylation step, two molecules of the same aromatic hydrocarbon are converted by a disproportionation reaction, and the aromatic hydrocarbon 1 having a lower molecular weight is converted. Molecule and one higher molecular weight aromatic hydrocarbon (xylene) molecule can be obtained. Specifically, two molecules of toluene can be converted to obtain one molecule of benzene and one molecule of xylene.
In the xylene production method of the present invention, (x) in the disproportionation / transalkylation step, two aromatic hydrocarbons having different carbon numbers are converted to obtain two xylene molecules by transalkylation reaction. Specifically, one molecule of toluene and one molecule of trimethylbenzene can be converted to obtain two molecules of xylene.

In the method for producing xylene of the present invention, the xylene is selectively produced by performing a disproportionation reaction or a transalkylation reaction between aromatic hydrocarbons in the (c) disproportionation / transalkylation step. Can do.
In the production method of the xylene production method of the present invention, the product oil obtained in the (c) disproportionation / transalkylation step preferably has a xylene content of 28 to 32% by volume, What is 32 volume% is more preferable, and what is 30-32 volume% is still more preferable.
In addition, in this application document, the content rate of xylene means the value measured according to JISK2536-2.

  According to the present invention, the catalytic cracking gasoline containing a low content of aromatic hydrocarbons and containing unsaturated hydrocarbons, sulfur, nitrogen, etc. is used as a raw material for conversion reaction such as disproportionation reaction or transalkylation reaction. While being used, it is possible to provide a method for producing xylene in a simple and high yield.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, these are illustrations, Comprising: This invention is not restrict | limited at all by these Examples.

Example 1
(A) Fractionation process The fluid catalytic cracking gasoline 1 having the composition and distillation characteristics shown in Table 1 was fractionated at a boiling range of 150 to 200 ° C. to obtain a raw material cracked gasoline 1. Table 2 shows the composition and distillation properties of the obtained raw material cracked gasoline 1.
(B) Hydrotreating process The obtained raw material cracked gasoline 1 was subjected to a reaction temperature of 300 ° C., a reaction pressure of 3.0 MPa, a liquid space velocity (LHSV) of 2.0 h ⁻¹ , hydrogen oil using a Co—Mo catalyst. By performing desulfurization and denitrification treatment under the conditions of a ratio of 300 NL / L and a reaction time of 2.0 hours, the sulfur content is 1 mass ppm, the nitrogen content is 1 mass ppm, and the aromatic hydrocarbon content is 53.6. A desulfurization / denitrification fluid catalytic cracking gasoline 1 having a volume% and an unsaturated hydrocarbon (olefin) content of 0.5 volume% was obtained. The composition of the obtained desulfurization / denitrification fluid catalytic cracking gasoline 1 is shown in Table 3.
Furthermore, this desulfurization / denitrification fluid catalytic cracking gasoline 1 is subjected to sulfolane treatment to extract aromatic hydrocarbons, so that 58.5% by volume of C9 aromatic hydrocarbons and C10 aromatic hydrocarbons are obtained. Was obtained as a disproportionated / transalkylated feedstock 1 containing 36.4% by volume. The composition of the resulting disproportionated / transalkylated feedstock 1 is shown in Table 4.
(C) Disproportionation / transalkylation step Using the above disproportionation / transalkylation feedstock 1 as a reaction catalyst, a Mo catalyst, a reaction temperature of 345 ° C., a liquid space velocity of 3 h ⁻¹ , a reaction pressure of 2.0 MPa, By subjecting the disproportionation / transalkylation reaction to a reaction time of 1.0 hour, the intended product oil 1 containing 30.9% by volume of xylene was obtained. The composition of the resulting product oil 1 is shown in Table 4.

(Example 2)
(A) Fractionation process The fluid catalytic cracking gasoline 2 having the composition and distillation characteristics shown in Table 1 was fractionated at a boiling range of 150 to 200 ° C. to obtain a raw cracking gasoline 2. Table 2 shows the composition and distillation properties of the obtained raw material cracked gasoline 2.
(B) Hydrotreating process The obtained raw material cracked gasoline 2 was subjected to a reaction temperature of 300 ° C., a reaction pressure of 3.0 MPa, a liquid space velocity (LHSV) of 2.0 h ⁻¹ , and a hydrogen oil ratio using a Co—Mo catalyst. By performing desulfurization and denitrification treatment under the conditions of 300 NL / L and reaction time of 2.0 h, the sulfur content is 1 mass ppm, the nitrogen content is 1 mass ppm, and the aromatic hydrocarbon content is 52.7 volumes. % Desulfurization / denitrification fluid catalytic cracking gasoline 2 having an unsaturated hydrocarbon (olefin) content of 0.6% by volume was obtained.
The composition of the obtained desulfurization / denitrification fluid catalytic cracking gasoline 2 is shown in Table 3. Further, the desulfurization / denitrification fluid catalytic cracking gasoline 2 is subjected to sulfolane treatment to extract aromatic hydrocarbons, whereby 58.1% by volume of C9 aromatic hydrocarbons and C10 aromatic hydrocarbons are obtained. Was obtained as a disproportionated / transalkylated feedstock 2 containing 36.9% by volume.
(C) Disproportionation / transalkylation step Using the above disproportionation / transalkylation feedstock 2 using a Mo catalyst as a reaction catalyst, a reaction temperature of 345 ° C., a liquid space velocity of 3 h ⁻¹ , a reaction pressure of 2.0 MPa, By performing a disproportionation / transalkylation reaction under a reaction time of 1.0 hour, a product oil 2 containing 31.0% by volume of xylene was obtained. The composition of the resulting product oil 1 is shown in Table 4.

(Example 3)
(A) Fractionation process The fluid catalytic cracking gasoline 3 having the composition and distillation characteristics shown in Table 1 was fractionated at a boiling range of 150 to 200 ° C. to obtain a raw cracking gasoline 3. Table 2 shows the composition and distillation properties of the obtained raw material cracked gasoline 3.
(B) Hydrotreating process The obtained raw material cracked gasoline 3 was subjected to a reaction temperature of 300 ° C., a reaction pressure of 3.0 MPa, a liquid space velocity (LHSV) of 2.0 h ⁻¹ , hydrogen oil using a Co—Mo catalyst. By performing desulfurization and denitrification treatment under the conditions of a ratio of 300 NL / L and a reaction time of 2.0 hours, the sulfur content is 1 mass ppm, the nitrogen content is 1 mass ppm, and the aromatic hydrocarbon content is 55. A desulfurization / denitrification fluid catalytic cracking gasoline 3 having 1% by volume and an unsaturated hydrocarbon (olefin) content of 0.6% by volume was obtained. The composition of the obtained desulfurization / denitrification fluid catalytic cracking gasoline 3 is shown in Table 3. Further, the desulfurization / denitrification fluid catalytic cracking gasoline 3 is subjected to sulfolane treatment to extract aromatic hydrocarbons, whereby 62.9% by volume of aromatic hydrocarbons having 9 carbon atoms and 10 hydrocarbon atoms are obtained. Was obtained as a disproportionated / transalkylated feedstock 3 containing 32.2% by volume. The composition of the resulting disproportionated / transalkylated feedstock 3 is shown in Table 4.
(C) Disproportionation / transalkylation step Using the above disproportionation / transalkylation feedstock 3 as a reaction catalyst, a Mo catalyst, a reaction temperature of 345 ° C., a liquid space velocity of 3 h ⁻¹ , a reaction pressure of 2.0 MPa, By subjecting the disproportionation / transalkylation reaction to a reaction time of 1.0 hour, the desired product oil 3 containing 31.2% by volume of xylene was obtained. The composition of the resulting product oil 3 is shown in Table 4.

(Comparative Example 1)
A product oil was obtained without subjecting the fluid catalytic cracking gasoline 1 to (a) fractionation step.
That is, a fluid catalytic cracking gasoline 1 having the composition and distillation characteristics shown in Table 1 was prepared by using a Co—Mo-based catalyst at a reaction temperature of 300 ° C., a reaction pressure of 3.0 MPa, a liquid space velocity (LHSV) of 2.0 h ⁻¹ , By performing desulfurization and denitrification treatment under the conditions of a hydrogen oil ratio of 300 NL / L and a reaction time of 2.0 hours, the sulfur content is 1 mass ppm, the nitrogen content is 1 mass ppm, and the aromatic hydrocarbon content is A desulfurization / denitrification fluid catalytic cracking gasoline 4 having 23.4% by volume and an unsaturated hydrocarbon (olefin) content of 0.6% by volume was obtained. The composition of the obtained desulfurization / denitrification fluid catalytic cracking gasoline 4 is shown in Table 3.
Further, this desulfurized fluid catalytic cracking gasoline 4 is treated with sulfolane to extract an aromatic fraction, whereby 25.8% by volume of C9 aromatic hydrocarbons and 21C of C10 aromatic hydrocarbons are extracted. A disproportionated / transalkylated feedstock 4 containing 4% by volume was obtained. The composition of the resulting disproportionated / transalkylated feedstock 4 is shown in Table 5.
The above disproportionated / transalkylated feedstock 4 was disproportionated under the conditions of using a Mo catalyst as a reaction catalyst, a reaction temperature of 345 ° C., a liquid space velocity of 3 h ⁻¹ , a reaction pressure of 2.0 MPa, and a reaction time of 1.0 hour. By performing the conversion / transalkylation, the desired product oil 4 was obtained. The composition of the resulting product oil 4 is shown in Table 5.

(Comparative Example 2)
The product oil was obtained without subjecting the fluid catalytic cracking gasoline 1 to hydrodesulfurization / denitrification reaction in the (b) hydrotreating step.
That is, fluid catalytic cracking gasoline 1 having the composition and distillation characteristics shown in Table 1 was fractionally distilled at a boiling range of 150 to 200 ° C. to obtain raw material cracked gasoline 1. Table 2 shows the composition and distillation properties of the obtained raw material cracked gasoline 1.
The obtained raw material cracked gasoline 1 is treated with sulfolane to extract aromatic hydrocarbons, so that 58.1% by volume of C9 aromatic hydrocarbons and 36.1% of C10 aromatic hydrocarbons are obtained. % Disproportionated / transalkylated feedstock 5 was obtained. The composition of the resulting disproportionated / transalkylated feedstock 5 is shown in Table 5.
This disproportionated / transalkylated feedstock 5 was disproportionated under the conditions of using a Mo catalyst as a reaction catalyst, a reaction temperature of 345 ° C., a liquid space velocity of 3 h ⁻¹ , a reaction pressure of 2.0 MPa, and a reaction time of 1.0 hour. An attempt was made to carry out the conversion / transalkylation, but the catalyst was deactivated during the reaction.

  From Table 1 to Table 4, in Examples 1 to 3, by sequentially performing treatments in (a) fractionation step, (b) hydrotreating step, and (c) disproportionation / transalkylation step. In addition, it is easy to use catalytic cracking gasoline containing a low content of aromatic hydrocarbons and containing unsaturated hydrocarbons, sulfur and nitrogen as raw materials for conversion reactions such as disproportionation or transalkylation. It can also be seen that xylene can be produced with a high yield.

  On the other hand, from Table 1 to Table 3 and Table 5, in Comparative Example 1, it was found that the yield of xylene was low because (a) the fractionation step was not performed, and in Comparative Example 2, (b) Since the hydrodesulfurization / denitrification reaction is not performed in the hydrotreating step, it can be seen that the reaction catalyst is deactivated during the reaction and cannot be put to practical use.

  According to the present invention, the catalytic cracking gasoline containing a low content of aromatic hydrocarbons and containing unsaturated hydrocarbons, sulfur, nitrogen, etc. is used as a raw material for conversion reaction such as disproportionation reaction or transalkylation reaction. While being used, it is possible to provide a method for producing xylene in a simple and high yield.

Claims (3)

A method for producing xylene, comprising:
(A) a fractionation step of subjecting fluid catalytic cracking gasoline to distillation to fractionate a fraction having a boiling range of 145 to 205 ° C;
(B) The hydrous desulfurization / denitrification reaction is performed on the fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step (a), so that the sulfur content is 0 to 6 ppm by mass and the nitrogen content is reduced. A hydrotreatment step of adjusting to 0 to 6 ppm by mass;
(C) including a disproportionation / transalkylation step in which a disproportionation reaction or a transalkylation reaction is performed on the product oil containing the aromatic hydrocarbon obtained in the above (b) hydrotreating step. A method for producing xylene.   (A) The fraction having a boiling range of 145 to 205 ° C. obtained in the fractionation step is 25 to 45% by volume of C9 aromatic hydrocarbons and 15 to 25 C10 aromatic hydrocarbons. The method for producing xylene according to claim 1, comprising vol%.   The method for producing xylene according to claim 1 or 2, wherein the (b) hydrotreating step is a step of further separating non-aromatic hydrocarbons after the hydrodesulfurization / denitrification reaction.