JPH0794396B2 - Method for producing aromatic hydrocarbon - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an aromatic hydrocarbon from a light hydrocarbon, and more specifically, to a zinc-containing compound having a specific composition and stability. The present invention relates to a method for stably producing an aromatic hydrocarbon from a light hydrocarbon in a high yield and using a superior ZSM-5 type zeolite catalyst.

(Prior Art) A method for producing ZSM-5 type zeolite is disclosed in Japanese Examined Patent Publication No. 46-10064 and the like. Further, Japanese Examined Patent Publication No. 56-42639 is composed of paraffin, olefin and / or naphthene, and has a content of aromatic hydrocarbons of 15% by weight or less from C ₅ ⁺ hydrocarbons to Z.
A method for producing aromatic hydrocarbons using SM-5 type zeolite as a catalyst is disclosed in JP-B-58-23368, which has a specific property prepared by a specific production method from C _{2 to} C ₄ paraffin, olefin or a mixture thereof. Disclosed is a method for producing an aromatic compound under specific conditions using a ZSM-5 crystalline silicate having ## STR3 ## as a catalyst. Furthermore, JP-A-55-51440
The issue, as a stabilizing method of the zeolite catalyst, I _B, I
I _B, the zeolite impregnated with a metal cation of Group VIII such as,
A method of suppressing the activity decrease due to dealumination phenomenon in the presence of steam by using in a reducing atmosphere for a shorter period of time for producing metal clusters and then regenerating in an oxidizing atmosphere is disclosed in JP-A-60-153944. A method of steaming and stabilizing under conditions that reduce the activity of the zeolite catalyst to no less than 25% of the activity of the fresh catalyst is disclosed.

(Problems to be Solved by the Invention) Although the catalysts for producing aromatic hydrocarbons from light hydrocarbons according to the prior art have relatively high initial activities, they have a large decrease in activity over time due to the accumulation of coke-like substances. The yield of group hydrocarbons is also greatly reduced, and in actual use, there are problems such as frequent regeneration at intervals of several hours to several tens of hours, which is not at a satisfactory level.

(Means for Solving Problems) As a result of intensive studies made by the present inventors on a catalyst for producing an aromatic hydrocarbon with a higher selectivity than a light hydrocarbon and stably, Zinc-containing ZS with properties
It has been found that when M-5 type zeolite is used as a catalyst, deterioration with time is extremely small and an aromatic hydrocarbon can be stably produced in a high yield.

That is, the present invention is a method for producing an aromatic hydrocarbon from a light hydrocarbon by using a ZSM-5 type zeolite containing zinc as a catalyst, wherein the ZSM-5 type zeolite satisfies the following (i) to (iii): And a method for producing an aromatic hydrocarbon.

(I) Atomic ratio of silicon / aluminum is 10 to 75 (ii) Atomic ratio of zinc / silicon is 0.008 to 0.03 (iii) Thermal desorption method using pyridine at a heating rate of 15 ° C / min. According to ZSM-5 at 500-900 ℃
The desorption amount of pyridine per 1 g of type zeolite is 40 to 120 μmol. The ZSM-5 type zeolite catalyst used in the present invention has an atomic ratio of silicon / aluminum of 10 to 75, preferably 12 to 50. When the ratio is more than 75, the catalytic activity is insufficient, and when it is less than 10, practically none is obtained. The atomic ratio of zinc / silicon is 0.008 to 0.03, preferably 0.01 to 0.0.
Is 2. A catalyst having a ratio of more than 0.03 has low catalytic activity, while a catalyst having a ratio of less than 0.008 has poor aromatic hydrocarbon selectivity even when used in the production of aromatic hydrocarbons. Further, the alkali metal content of the ZSM-5 type zeolite catalyst of the present invention is 0.05 in terms of alkali metal / aluminum atomic ratio.
The following are preferable. When this ratio exceeds 0.05, the activity of the catalyst becomes poor.

The crystal grain size of the ZSM-5 type zeolite catalyst used in the present invention is particularly preferably 1 μm or less. The crystal grain size in the present invention refers to an average value of lengths of individual zeolite particles in the shortest direction observed by a scanning electron microscope. The length in the shortest direction is, for example, the diameter when the zeolite particles are spherical, the thickness when the plate-like shape, the smaller thickness when the rod-like shape, and the primary particle when the particles are agglomerated. The particle size. The specific surface area of ZSM-5 type zeolite catalyst is 280 to 340 m ² / g when measured by the nitrogen adsorption method.
Are preferred.

The ZSM-5 type zeolite catalyst used in the present invention is pyridine, and the ZSM-5 type zeolite at 500 to 900 ° C. by the temperature programmed desorption method when the temperature rising rate is 15 ° C./min.
The desorption amount of pyridine per g is 40 to 120 μmol. Regarding the temperature programmed desorption method, see Yasumori "Chemicals and Industry", No. 19
Vol. 10, No. 10, pp. 1208-1214 (1966).
As a temperature programmed desorption method for SM-5 type zeolite, "catalyst",
25 , pages 97-99 (1983), etc.

The temperature programmed desorption method using pyridine referred to in the present invention is as follows.
Saturately adsorb pyridine on the catalyst to be measured at 180 ℃, raise it at a constant rate of 15 ℃ per minute, and desorb the pyridine that is desorbed as the temperature rises to 500 ℃ to 900 ℃. It is detected by a flame ionization detector, and the desorption amount is obtained as a pyridine conversion amount using a pyridine calibration curve.

The apparatus for measuring the temperature programmed desorption amount used in the present invention is shown in FIG.
The sample, that is, the catalyst 4 to be measured is crushed into 20 to 30 meshes and put into a stainless steel sample tube 3 having an inner diameter of 6 mmφ, an outer diameter of 8 mmφ and a length of 150 mm. Cylinder-filled nitrogen as carrier gas is flowed while controlling with the gas flow meter 1 at a flow rate of 60 ml / min. Pyridine is injected from a silicon rubber injection port 5 by 2 to 5 μm using a microsyringe. After adsorbing almost all the amount, 10 minutes later, and when unadsorbed content is observed, when the detector confirms the completion of the outflow, the next injection is performed, and the injection is repeated until saturated adsorption is reached. Once saturated adsorption of pyridine on the catalyst is complete, the inner diameter of the furnace core tube 22
The temperature is raised at a rate of 15 ° C./min in a tubular electric furnace 2 having a mmφ and a length of 65 mm. Here, the gas flow path from around the pyridine injection port 5 to the hydrogen flame ionization detector 6 is heated by a ribbon heater 8 or the like except the inside of the electric furnace, and the outside is covered with a heat insulating material 9 to 180- Keep warm at 200 ° C. The temperature detection is performed at the position of the temperature detection end 7 closely attached to the outside of the sample tube. Temperature When the detected temperature at the sample end 7 reaches 500 ° C, further increase the temperature to 9
Pyridine desorbed from the sample 4 is detected by a hydrogen flame ionization detector (FID detector) 6 until the temperature reaches 00 ° C., and the desorbed amount is converted using a calibration curve of pyridine.

The desorption amount of pyridine obtained by the above method is 40μ per 1g of catalyst.
If it is less than mol, the catalytic activity is insufficient, and if the amount of pyridine released exceeds 120 μmol per 1 g of catalyst, the stability of the catalyst over time is poor.

The catalyst used in the present invention is, for example, JP-B-46-10064.
ZSM-5 type zeolite synthesized by a publicly known method such as No. No. etc. is converted into a proton type by a publicly known method, and zinc is contained by a method such as an ion exchange method or an impregnation method, and then heat treatment, preferably heating in the presence of steam is performed. It is prepared by processing. Suitable conditions for heat treatment under steam conditions are a temperature of 600 to 800 ° C., a water pressure of 0.1 to 1 atm, and a 0.2.
~ 20 hours processing time. The steam may be diluted with air or an inert gas such as nitrogen before use. A more preferable temperature and time range is the range surrounded by A, B, C and D shown in FIG.

If the treatment temperature is too low or the treatment time is too short, the amount of pyridine desorbed in the catalyst after the treatment will be too large. Conversely, if the treatment temperature is too high or the treatment time will be too long, the pyridine of the catalyst after the treatment will be too large. The desorption amount becomes too small.

In addition, in order to give an appropriate catalyst particle shape upon use, a commonly used porous inorganic binder such as alumina or silica may be blended, or a hydrogenated / dehydrogenated metal component may be further added and used.

The light hydrocarbon used in the method of the present invention is a hydrocarbon containing paraffin and may contain olefin, and having a boiling point of 190 ° C. or lower. Preferably, the aromatic hydrocarbon content is 15% by weight or less and the number of carbon atoms is 4 or more.

The reaction conditions vary depending on the raw material hydrocarbon, but 400
~ 600 ℃ temperature, 0.1 ~ 10hr ^-1 weight hourly space velocity (WHSV),
0.5-10 atm pressure, preferably 450-550 ° C temperature, 0.2
Weight space velocities of ~ 2hr ^-1 and pressures of 0.8-5 atmospheres are employed.

Since the catalyst of the method of the present invention has excellent stability, it can be used in any of the fixed bed, moving bed and fluidized bed systems, but particularly when it is used in the fixed bed system, a remarkable effect is exhibited.
In other words, the fixed bed system is simple in terms of equipment and the regeneration interval can be greatly extended.

(Effects of the Invention) According to the method of the present invention, aromatic hydrocarbons can be produced from light hydrocarbons in high yield and stably over time. Therefore, the catalyst can be regenerated repeatedly for a long period of time, and the frequency of regeneration can be reduced. Since the catalyst of the method of the present invention has excellent stability,
Can be used efficiently with the fixed bed system.

(Examples) Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Reference Example 1 Preparation of catalyst Solution A prepared by dissolving 290 g of sodium silicate (water glass No. 3) in 230 g of distilled water, and separately 11.4 g of aluminum sulfate 16-hydrate, 50 g of tetrapropylammonium bromide and 13 g of sulfuric acid were dissolved in 300 g of distilled water. The prepared solution B was prepared. Then, using a homogenizer, solution B was added to solution A with vigorous stirring to form a homogeneous mixed gel. This gel was charged into one autoclave, and kept and crystallized for 35 hours under stirring at 160 ° C. and 1000 rpm. After the reaction, the solid is filtered, washed with water, dehydrated and dried, and then 550
Calcination was performed in the air for 3 hours.

When the obtained white powder was confirmed by X-ray diffraction, ZSM-
A diffraction pattern of Form 5 was shown. Si / A by fluorescent X-ray analysis
When the l ratio was determined, it was 23. When the particle shape was observed with a scanning electron microscope (X-650 type 1 manufactured by Hitachi, Ltd.) at a magnification of 5000, a spherical average particle diameter of 0.5 μm and some aggregates were also observed.

Using 10% ammonium chloride aqueous solution for this zeolite,
Ion exchange was carried out by a conventional method to obtain H-type zeolite. Then, impregnate with a 5% aqueous solution of zinc nitrate, evaporate to dryness, dry,
Baking (500 ° C, 3 hours), zinc-containing zeolite catalyst A
Was prepared.

When the Zn / Si and Na / Al ratios were determined by fluorescent X-ray analysis, they were 0.017 and 0.02, respectively. The specific surface area measured by the nitrogen adsorption method was 340 m ² / g. In addition, when the desorption amount of pyridine was measured by the temperature programmed desorption method, the desorption amount at 500 to 900 ° C was
It was 300 μmol / g-catalyst. As the measurement sample, powder was crushed by compression molding, sized to 20 to 30 mesh, dried at 400 ° C. for 1 hour, and used. The measuring method and conditions were as described above in the text. The tubular electric furnace and the temperature control device used were a Shimadzu Corporation thermal analyzer (DT-30), and the FID detector used was a Shimadzu gas chromatograph (GC-8A) detector.

Desorption amount of pyridine shown in the following examples, unless otherwise specified, all measured under the method and conditions described above, 500 ~ 900 ℃
Is the amount of pyridine desorbed.

Reference Example 2 Preparation of catalyst In the same manner as in Reference Example 1, except that the amount of raw material aluminum was reduced, ZSM-5 zeolite having a Si / Al ratio of 50 and a particle size of 0.9 μ was synthesized. Next, it is made into a proton type and contains zinc,
Zn / Si = 0.015, Na / Al = 0.03, pyridine desorption amount is 260μ
An H-type zeolite catalyst C containing mol / g of zinc was prepared.

Reference Example 3 Preparation of Catalyst Reference Example except that silica sol (containing 30% by weight as silica) was used as a silica source, sodium hydroxide was used without adding an aluminum source, and the pH of the gel composition was adjusted to 10.8. A high silica zeolite was synthesized in the same manner as in 1. The X-ray diffraction pattern of the obtained zeolite is
It was a ZSM-5 type, had a Si / Al ratio of 100 or more, and had a crystal shape of a spherical shape with an average diameter of 4 μm. This was made into a proton type in the same manner as in Reference Example 1 to obtain a catalyst H in which zinc was impregnated and supported.

The catalyst had a Zn / Si ratio of 0.014 and a pyridine desorption amount of 85 μmo.
It showed l / g.

Reference Example 4 Preparation of catalyst As in Reference Example 1, except that the amount of aluminum sulfate was 25
The amount of g and the amount of sulfuric acid were 1.0 g, and zeolite was synthesized to obtain ZSM-5 zeolite having a particle size of 0.2 μ and a Si / Al ratio of 13. Then, the proton type, containing zinc, Zn / Si ratio 0.01
8. Catalyst I with Na / Al ratio 0.02 was prepared. The specific surface area of this catalyst I is 340 m ² / g, and the desorption amount of pyridine is 360 μmol / g
It was.

Example 1 The catalyst A prepared in Reference Example 1 was compression molded into 9 to 20 mesh, sized, and then filled in a 10 mmφ quartz reaction tube to obtain 80% by volume.
It was treated at 650 ° C. for 2 hours in steam (atmospheric pressure) diluted with nitrogen (catalyst B).

The specific surface area of this catalyst was 330 m ² / g, and the temperature programmed desorption amount of pyridine was 110 μmol / g. This catalyst was filled in a 10 mmφ stainless steel reaction tube, and n-hexane was supplied and reacted. The reaction conditions and results are shown in Table 1. In addition, as an index showing the stability of these reactions over time, the liquid passing time until the decomposition activity becomes 1/2 is also shown as a half-life.

In addition, For the decomposition activity, the value of the reaction rate constant (k) obtained by the following equation was used, and the time until this value became 1/2 was defined as the half-life.

x: Conversion of raw material hydrocarbon θ: Contact time Example 2 The catalyst C prepared in Reference Example 2 was treated in 80% by volume steam at 650 ° C. for 5 hours in the same manner as in Example 1 (Catalyst D).
This specific surface area is 315 m ² / g, and the temperature programmed desorption amount of pyridine is 85.
It showed μmol / g. This catalyst D was treated with n as in Example 1.
-Subjected to hexane reaction. The results are also shown in Table 1.

Example 3 The catalyst I prepared in Reference Example 4 was prepared as in Example 1, except that
Heat treatment was performed in steam at 80% by volume for 1 hour at 750 ° C. (catalyst J). The specific surface area of this catalyst J was 310 m ² / g, and the temperature programmed desorption amount of pyridine was 73 μmol / g. This catalyst J was subjected to the reaction of n-hexane in the same manner as in Example 1. The results are also shown in Table 1.

Example 4 The catalyst A prepared in Reference Example 1 was used as in Example 1, except that
Heat treatment was carried out in steam at 80% by volume for 2 hours at 700 ° C. (catalyst K). The desorption amount of pyridine of this catalyst K at temperature rise is 90μ.
It was mol / g. This catalyst was subjected to the reaction of n-hexane in the same manner as in Example 1. The results are also shown in Table 1.

Example 5 Using the prepared catalyst B, C ₅ hydrocarbon (75% by weight of paraffin,
Aromatization reaction of olefin (25% by weight) was carried out. The reaction conditions and results are shown in Table 2.

Example 6 Using catalyst B, an aromatization reaction of C ₄ hydrocarbons (50% isobutane, 50% n-butane) was carried out.

It was carried out at a reaction temperature of 510 ° C. and atmospheric pressure at WHSV of 0.3 hr ⁻¹ . The aroma yield in the initial 2 hours was 50% by weight. Example 1
Similarly, the half-life was calculated to be 50 days.

Example 7 The catalyst A prepared in Reference Example 1 was heat-treated in air at 850 ° C. for 10 hours to obtain a catalyst L. The specific surface area of this catalyst L is 310 m
^The amount of desorbed pyridine was ² / g, and the amount of pyridine released was 100 μmol / g.

This catalyst was subjected to the reaction of n-hexane in the same manner as in Example 1. The reaction conditions were 500 ° C., WHSV = 0.5 hr ⁻¹ and atmospheric pressure. The aroma yield after 10 hours was 50% by weight, and it was confirmed that the half-life was 50 days, which was extremely stable.

Example 8 Using the catalyst K prepared in Example 4, as in Example 1,
However, n-hexane was reacted at a reaction temperature of 530 ° C., WHSV = 0.8 hr ⁻¹ , hydrogen / raw material hydrocarbon = 1, and a pressure of 3 atm.

The aroma yield at 2 hours after passing the solution was 47% by weight, and the aroma yield at 200 hours was 47% by weight, which was extremely stable. As with Example 1, the half-life was determined to be 45 days. Atsuta

Example 9 Silica sol was added to the catalyst K prepared in Example 4, and the mixture was kneaded and extrusion-molded to obtain catalyst particles having a zeolite / silica binder = 70/30 weight ratio of about 1 mmφ × 2 mm length. This was subjected to C ₅ hydrocarbon reaction as in Example 5. Reaction conditions are 510
C., WHSV = 0.5 hr ⁻¹ (based on zeolite), and atmospheric pressure. As a result, the aroma yield at 2 hours after the reaction was 49% by weight, and the half-life was 60 days.

Example 10 Using the granulation catalyst prepared in Example 9, C ₄ hydrocarbons (60% by weight of isobutane and 40% by weight of n-butene) were used at a reaction temperature of 510.
The reaction was carried out under the conditions of ℃, WHSV = 0.7hr ⁻¹ and atmospheric pressure.

The aroma yield in the second hour after the reaction was 56% by weight.
The aroma yield at the 00th hour was 54% by weight, and the decrease in activity was extremely small.

Comparative Example 1 The catalyst A prepared in Reference Example 1 was used in the same manner as in Example 1, except that
The conditions were changed to 850 ° C. for 1 hour, and heat treatment was performed under steam to obtain catalyst E. The specific surface area of this catalyst is 250 m ² / g
Thus, the temperature programmed desorption amount of pyridine was 17 μmol / g. This catalyst was subjected to the reaction of n-hexane in the same manner as in Example 1. As a result of carrying out at a reaction temperature of 515 ° C., WHSV = 0.6 hr ⁻¹ and atmospheric pressure, the aroma yield was as low as 14% by weight.

Comparative Examples 2 to 6 Catalysts A, H, I and Catalyst A prepared in Reference Example 1 were used in the same manner as in Example 1, except that 550 ° C. and 1 hour steam 80% by volume.
Catalyst F heat-treated under the following conditions (the temperature-programmed desorption amount of pyridine was 180 μmol / g), and further, Catalyst C prepared in Reference Example 2 was treated at 538 ° C. and 100% steam for 8 hours. G (the temperature-programmed desorption amount of pyridine was 150 μmol / g), and each was subjected to the reaction of n-hexane in the same manner as in Example 1. The results are shown in Table 3.

It can be seen that these comparative catalysts have large deterioration over time and have a short half-life.

Comparative Example 7 Using the catalyst C prepared in Reference Example 2, as in Example 1, n
-The conversion reaction of hexane was carried out at 515 ° C, WHSV = 8 hr ^-1 and atmospheric pressure. The result was an aroma yield of 47% and a half-life of 1 day.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus for measuring the temperature programmed desorption amount of a catalyst using pyridine, and FIG. 2 is a table showing an optimum condition range of the heat treatment under steam of the catalyst.

Claims (3)

[Claims] 1. A method for producing an aromatic hydrocarbon from a light hydrocarbon using a ZSM-5 type zeolite containing zinc as a catalyst, wherein the ZSM-5 type zeolite has the following (i) to (iii):
A method for producing an aromatic hydrocarbon, which satisfies: (I) Atomic ratio of silicon / aluminum is 10 to 75 (ii) Atomic ratio of zinc / silicon is 0.008 to 0.03 (iii) Thermal desorption method using pyridine at a heating rate of 15 ° C / min. According to ZSM-5 at 500-900 ℃
Desorption of pyridine is 40-120μmol per 1g of zeolite 2. The process for producing an aromatic hydrocarbon according to claim 1, which is carried out at a temperature of 450 to 550 ° C., a weight hourly space velocity of 0.2 to 2 hr ^{−1 and} a pressure of 0.8 to 5 atm. 3. A light hydrocarbon having 4 or more carbon atoms and a boiling point of 19
The method for producing an aromatic hydrocarbon according to claim 1 or 2, wherein the aromatic hydrocarbon content is 0% or less and the aromatic hydrocarbon content is 15% by weight or less.