KR100973242B1 - Regeneration of Dehydrogenation Catalyst - Google Patents

Abstract

The present invention relates to a method for regenerating a dehydrogenation catalyst, and more specifically, to a hydrocarbon having a ring structure of 11 or more carbon atoms using an alumina catalyst loaded with tin (Sn) and platinum (Pt) as an aromatic compound of the same ring. The present invention relates to a method of regenerating by reducing hydrogen and simultaneously reducing the coke on the surface of the catalyst accompanying the digestion reaction. According to the regeneration method of the dehydrogenation catalyst according to the present invention, the conversion and selectivity of the dehydrogenation reaction can be stably maintained, and the regeneration of the dehydrogenation catalyst can be carried out with the dehydrogenation process. There is no economic advantage because it does not cost.

1,5-dimethylnaphthalene, 1,5-dimethyltetraline, dehydrogenation catalyst, catalyst regeneration

Description

Regeneration of Dehydrogenation Catalyst

The present invention relates to a method for regenerating a dehydrogenation catalyst, and more specifically, to a hydrocarbon having a ring structure of 11 or more carbon atoms using an alumina catalyst loaded with tin (Sn) and platinum (Pt) as an aromatic compound of the same ring. The present invention relates to a method of regenerating by reducing hydrogen and simultaneously reducing the coke on the surface of the catalyst accompanying the digestion reaction.

Tin (Sn) and platinum (Pt) -supported alumina catalysts are dehydrogenation catalysts used in the process of dehydrogenating hydrocarbons having a ring structure of 11 or more carbon atoms and converting them into aromatic compounds of the same ring, in particular, 1,5- It is usefully used to dehydrogenate dimethyl tetralin (1,5-DMT) to 1,5-dimethylnaphthalene (1,5-DMN).

For reference, 1,5-DMN has excellent mechanical, thermal, and chemical stability, so it can be used for various commercial purposes such as plastic bottle, LCD panel, magnetic tape, film for other codes, high temperature insulation tape, planar heating film, and electronic materials. Intermediates for the production of "polyethylenenaphthalene (PEN)" used, ortho-Xylene and 1,3-butadiene (1,3-Butadiene) through 5- OTP is produced, 1,5-DMT through cyclization, 1,5-DMN through dehydrogenation, 2,6-DMN through isomerization, and purification through crystallization Produce 2,6-DMN. Oxidation and purification using acetic acid again produces 2,6-naphthalene dicarboxylic acid (hereinafter referred to as 2,6-NDA), a monomer of PEN. Finally PEN is generated.

However, such dehydrogenation catalysts have a long period of use, and thus, carbon deposits, such as coke, adhere to the surface of the catalyst or penetrate into the pores of the catalyst to lower the dehydrogenation reaction. Therefore, it is necessary to increase the reaction efficiency by removing them. To this end, research has been made on a method of regenerating a catalyst having a reduced reaction efficiency.

According to “On the Regeneration of Coked H-ZSM-5 Catalysts” (Sung-Jeng Jong et al., Journal of Catalysis, 174, 210-218 (1998), ARTICLE NO.CA981971), It can be seen that the conversion and selectivity similar to the catalyst used.

In addition, Patent No. 10-828856 discloses a method for regenerating a zeolite beta catalyst used for cyclization of 5-ortho-Tolylpentene, but to date dehydrated alumina There is no known method for regenerating the digestion catalyst.

Accordingly, the present invention provides a method for regenerating an alumina catalyst loaded with tin (Sn) and platinum (Pt) used in a process for dehydrogenating a hydrocarbon having a ring structure having 11 or more carbon atoms and converting it into an aromatic compound having the same ring. The purpose. In particular, an object of the present invention is to provide an economical method for regenerating the catalyst by simplifying the process and increasing the efficiency by regenerating the catalyst with the dehydrogenation reaction.

In order to achieve the above object, the regeneration method of the alumina catalyst loaded with tin (Sn) and platinum (Pt) according to the present invention is a ring structure having 11 or more carbon atoms using an alumina catalyst loaded with tin (Sn) and platinum (Pt). In the regeneration of the catalyst, which is accompanied by a reaction process of dehydrogenating a hydrocarbon having a hydrogen to an aromatic compound of the same ring, an oxygen-diluted gas is injected into nitrogen at a temperature of 400 to 600 ° C. and attached to the surface of the catalyst. Oxidizing and burning the coke, removing the reactants of the oxygen and the coke, drying the catalyst, and reducing the catalyst with hydrogen at a temperature of 200 to 400 ° C.

In addition, the oxidation temperature according to the present invention is preferably the reactor internal temperature is 450 ~ 550 ℃.

At this time, the volume ratio of oxygen and nitrogen of the gas in which oxygen is diluted in nitrogen is preferably in the range of 0.03: 1 to 0.27: 1.

In regeneration of the alumina catalyst on which tin (Sn) and platinum (Pt) are supported, the time for regenerating the catalyst is preferably 60 hours or more.

Finally, the hydrocarbon having a ring structure of 11 or more carbon atoms in which the alumina catalyst loaded with tin (Sn) and platinum (Pt) according to the present invention is used as a dehydrogenation catalyst is 1,5-dimethyltetraline and is produced as a result of the reaction. Typical examples of the aromatic compound of the same ring are 1,5-dimethylnaphthalene.

The present invention can ensure the stability of the process by stably maintaining the conversion and selectivity of the reaction converted to an aromatic compound of the same ring by dehydrogenation of hydrocarbons having a ring structure of 11 or more carbon by regenerating a dehydrogenation catalyst that is less reactive There is an advantage to that.

In addition, since the dehydrogenation catalyst is regenerated along with the dehydrogenation process, not only a separate device or an additional process is required, but also the catalyst can be regenerated more than four times through the present invention, thereby reducing the amount of catalyst used. In addition, it is also economically effective as it reduces the waste disposal cost of the spent catalyst.

And, by reducing the generation of waste can create an effect that can reduce the environmental pollution.

Preferred examples of the dehydrogenation of hydrocarbons having a ring structure of 11 or more carbon atoms include dehydrogenation of dimethyl tetralin to dimethylnaphthalene. For the sake of explanation, hydrocarbons having a ring structure of 11 or more carbon atoms include 1, 5-dimethyltetraline (DMT), the aromatic product of which is described as 1,5-dimethylnaphthalene (DMN).

1 shows a regeneration apparatus for a 1,5-DMT dehydrogenation catalyst according to an embodiment of the present invention, wherein the catalyst can be regenerated with dehydrogenation of 1,5-DMT to 1,5-DMN. It is a schematic of the device.

As shown in Figure 1, the configuration of the device is a 1,5-DMT storage tank (1), 1,5-DMT injection pump (2), Gas inlet (3), dehydrogenation fixed bed reactor (4), inside the reactor It consists of a thermometer (5), a jacket heat source supply device (6), a pressure gauge (7), a 1,5-DMN storage tank (8), a collection drum (9), and an activated carbon bed (10).

Before looking at the method for regenerating the dehydrogenation catalyst according to the present invention, the process of dehydrogenation of 1,5-DMT will be described.

The dehydrogenation catalyst used in the present invention is prepared by the method described in Korean Patent Laid-Open Publication No. 2000-0026638 and 2005-0054559 in which the ratio of platinum and tin is 0.1-10 w / w% using alumina as a carrier. After removing water and impurities in the fixed bed reactor 4 filled with such a dehydrogenation catalyst, the dehydrogenation catalyst is reduced using hydrogen. Then, the internal temperature of the fixed bed reactor 4 is set to 250 ° C. using the jacket heat source supply device 6, and then the injection pump 2 is operated so that 1,5-DMT of the storage tank 1 is fixed bed reactor 4. To be injected. At this time, the injection rate is 1 ~ 10L / hr, preferably 3 ~ 6L / hr, the temperature is 250 ~ 450 ℃, the pressure proceeds the dehydrogenation reaction under 5 ~ 15 atm. Thereafter, 1,5-DMN generated in the fixed bed reactor (4) is stored in the 1,5-DMN storage tank (8), the hydrogen generated as a result of the reaction to the upper 1,5-DMT storage tank and activated carbon bed (10) It is removed via.

During the dehydrogenation reaction, the conversion and selectivity to 1,5-DMN are continuously checked through gas chromatography (GC) analysis. (The conversion and selectivity of 1,5-DMN is based on the following equation.)

Conversion (%) = (1, before reaction, the amount of 5- DMT) - (amount of 1,5- DMN after the reaction) x 100

                         Amount of 1,5-DMT Before Reaction

Selectivity (%) = ( quantity of 1,5- DMN ) x 100

             (Amount of 1,5-DMT before reaction)-(amount of 1,5-DMN after reaction)

When the conversion and selectivity of 1,5-DMN drops to 30 to 70%, more preferably 50 to 60%, the dehydrogenation reaction is stopped and the dehydrogenation catalyst is regenerated in the following manner.

1. Removing material inside the reactor

First, the internal temperature of the fixed bed reactor 4 is lowered to 200 ° C., and the valves connected to the 1,5-DMT injection pump 2 and the 1,5-DMN storage tank 8 are closed. The pressure difference inside and outside the reactor is used to discharge 1,5-DMT or 1,5-DMN in the reactor to the collecting drum 9. When 1,5-DMT and 1,5-DMN are not discharged from the reactor 4 due to low internal pressure, 99.9% of nitrogen or helium is injected into the gas inlet 3 for a sufficient time, thereby remaining 1 in the reactor. Allow complete removal of, 5-DMT and 1,5-DMN and debris. At this time, the pipe connected to the collection drum 9 is heated by steam or electric heating wire to prevent clogging in the pipe due to 1,5-DMT or 1,5-DMN.

2. Removing Coke from the Catalyst Surface

As described above, a gas (oxygen and nitrogen mixing ratio of 0.03: 1 to 0.27: 1) in which oxygen is diluted to nitrogen through the gas inlet 3 into the reactor 4 in which the reactants and the foreign substances are removed is preferably 0.1 to 5 atmospheres. Is injected at 0.5 to 1 atmosphere, and the temperature in the reactor is raised to 400 to 450 ° C. at 1 to 10 ° C./min to oxidize and burn coke on the surface of the catalyst. At this time, if the internal temperature changes suddenly, stop raising the temperature and wait until the temperature becomes constant. After oxidizing for enough time to completely remove the coke, the temperature of the reactor was lowered to 300 ° C., and 99.9% nitrogen or helium gas was introduced for about 1 hour through the gas inlet (3). It releases carbon dioxide, water and oxygen. Carbon monoxide, carbon dioxide, and water discharged out of the reactor are then discharged into the atmosphere through the collection drum 9 and the activated carbon bed 10.

3. Activating the catalyst

As described above, the coke on the surface of the catalyst is oxidized and burned with a gas diluted with oxygen in nitrogen, and the by-products are removed in the reactor, and then 99.9% hydrogen is injected into the reactor to activate the catalyst. At this time, the temperature in the reactor is adjusted to 300 ℃.

By the above method, the catalyst used in the process can be regenerated in conjunction with the dehydrogenation process of converting a hydrocarbon having a ring structure of 11 or more carbon atoms such as 1,5-dimethyltetraline into an aromatic compound of the same ring.

On the other hand, the following experiment was conducted to find the optimum reaction conditions in relation to the regeneration of the dehydrogenation catalyst. The following examples are merely to illustrate preferred embodiments of the present invention and should not be construed as limiting the protection scope of the present invention in any sense.

Example  One

In order to find out the proper regeneration time for regenerating the catalyst, the following experiment was carried out.

The catalyst used in the present invention used an alumina catalyst loaded with platinum (Pt) and tin (Sn) having a ratio of platinum to tin of aluminum of 0.5 w / w%, respectively. After removing water and impurities in the reactor (3 inches x 68 inches fixed bed reactor) filled with the dehydrogenation catalyst, the dehydrogenation catalyst was reduced using hydrogen. Then, using the jacketed heat source supply device, the reactor internal temperature was set to 300 ° C., and then an injection pump was operated to inject 1,5-DMT into the reactor at a rate of 4 L / hr. The dehydrogenation reaction proceeds under). When the conversion rate to 1,5-DMN is less than 50 ~ 60%, the valves of the 1,5-DMT injection pump and 1,5-DMN storage tank are shut off to stop the dehydrogenation reaction, and the regeneration time is 20 hours, The catalyst was regenerated at different settings of 40 hours, 60 hours and 80 hours.

When regenerating the catalyst, the temperature of the reactor was increased from 200 ° C to 2 ° C / min and maintained at 450 ° C. Oxygen-diluted gas (oxygen: nitrogen = 0.12: 1) was injected into nitrogen to burn the coke on the catalyst surface. After lowering the temperature of the reactor to 10 ° C./min and injecting 99.9% nitrogen gas at 200 ° C., the reaction product, ie, carbon monoxide, carbon dioxide, water, oxygen, etc. remaining inside for 1 hour is collected and the activated carbon bed After release to the atmosphere through the injection of 99.9% hydrogen gas for 10 to 20 minutes to activate the catalyst. Thereafter, while performing the dehydrogenation reaction again, the conversion and selectivity were checked through gas chromatography, and the results were obtained as shown in Table 1.

catalyst
use
term New catalyst 20 hours playback 40 hours of playback 60 hours of playback 80 hours of playback Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity 1 day 99% 100% 96% 96% 98% 99% 99% 100% 98% 100% 10 days 97% 100% 90% 92% 95% 97% 97% 98% 98% 99% 20 days 96% 100% 84% 84% 92% 94% 98% 99% 97% 98% 30 days 97% 98% 77% 80% 88% 89% 93% 95% 94% 96% 40 days 93% 99% 69% 72% 82% 83% 90% 91% 90% 93% 50 days 92% 96% 60% 62% 76% 79% 86% 89% 88% 92% 60 days 90% 93% 49% 50% 72% 73% 83% 88% 85% 89% 70 days 88% 91% 35% 33% 66% 68% 80% 83% 82% 80% 80 days 85% 88% 28% 30% 57% 60% 76% 77% 78% 78% 90 days 80% 83% 17% 33% 48% 53% 71% 72% 74% 76% 100 days 76% 80% 12% 28% 33% 42% 64% 70% 64% 69% 110 days 70% 74% 11% 25% 20% 36% 56% 65% 57% 59% 120 days 62% 65% 10% 23% 10% 27% 47% 57% 49% 53%

Looking at the difference in the conversion rate according to the new catalyst and the regeneration time of Table 1, when the regeneration time is more than 60 hours came out a stable conversion rate. Considering the economic aspect, it can be seen that 60 hours of play time is appropriate.

Example  2

In order to find out the appropriate regeneration temperature for regenerating the catalyst, the following experiment was conducted.

The regeneration temperature was set differently to 350 ° C., 450 ° C., and 550 ° C., and the rest of the conditions were the same as those of Example 1 except for the regeneration time (set to 60 hours). In addition, the conversion and selectivity through gas chromatography were checked every 12 hours, and the results were obtained as shown in Table 2 at intervals of 10 days. At this time, if the regeneration temperature is more than 600 ℃ carbonized in the reactor causing the clogging phenomenon in the reactor was carried out at a temperature of less than 600 ℃.

catalyst
Period of use New catalyst Temperature 350 ℃ Temperature 450 ℃ Temperature 550 ℃ Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity 1 day 99% 100% 96% 99% 99% 100% 99% 100% 10 days 97% 100% 94% 97% 97% 98% 99% 100% 20 days 96% 100% 91% 95% 98% 99% 98% 99% 30 days 97% 98% 86% 90% 93% 95% 95% 97% 40 days 93% 99% 81% 87% 90% 91% 92% 90% 50 days 92% 96% 74% 82% 86% 89% 86% 89% 60 days 90% 93% 69% 76% 83% 88% 84% 85% 70 days 88% 91% 60% 64% 80% 83% 81% 80% 80 days 85% 88% 51% 59% 76% 77% 75% 78% 90 days 80% 83% 39% 47% 71% 72% 70% 74% 100 days 76% 80% 28% 39% 64% 70% 65% 69% 110 days 70% 74% 17% 30% 56% 65% 56% 63% 120 days 62% 65% 10% 22% 47% 57% 48% 56%

Looking at the difference in the conversion rate according to the new catalyst and the regeneration temperature of Table 2, when the regeneration temperature after regeneration is more than 450 ℃ came out a stable conversion rate. Considering the economic aspect, it can be seen that the regeneration temperature is suitable for 450 ℃.

Example  3

In order to find out the recovery time of the catalyst and the proper use period, the following experiment was conducted.

The number of regenerations is set differently once, twice, three times and four times, and the regeneration time and regeneration temperature are set to 60 hours and 450 ° C. according to the results of the above examples, and the rest of the conditions are the same as in Example 1. The dehydrogenation reaction and regeneration of the catalyst were carried out. Conversion rate and selectivity were checked every 12 hours by GC, and the results are shown in Table 3 at 10-day intervals.

New catalyst 1 play 2 play 3 play 4 play Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity 1 day 99% 100% 99% 100% 99% 100% 99% 100% 98% 100% 10 days 97% 100% 97% 98% 98% 100% 96% 98% 96% 100% 20 days 96% 100% 98% 99% 92% 96% 90% 97% 91% 94% 30 days 97% 98% 93% 95% 90% 92% 87% 94% 85% 92% 40 days 93% 99% 90% 91% 88% 90% 84% 90% 79% 87% 50 days 92% 96% 86% 89% 84% 88% 81% 86% 75% 82% 60 days 90% 93% 83% 88% 80% 84% 77% 83% 71% 81% 70 days 88% 91% 80% 83% 76% 80% 73% 80% 68% 71% 80 days 85% 88% 76% 77% 73% 76% 70% 78% 62% 70% 90 days 80% 83% 71% 72% 68% 73% 65% 74% 59% 71% 100 days 76% 80% 64% 70% 61% 69% 59% 69% 50% 64% 110 days 70% 74% 56% 65% 54% 66% 51% 62% 42% 56% 120 days 62% 65% 47% 57% 43% 52% 41% 51% 35% 47%

Looking at the usage period of the conversion rate more than 70% in Table 3, it can be seen that the new catalyst is 110 days, 90 days for one playback, 85 days for two playbacks, 80 days for three playbacks, and about 60 days for four playbacks. have.

Example 4

The following experiments were conducted to determine the temperature change and conversion and selectivity after regeneration according to the type of oxygen source.

Oxygen source uses air (79% nitrogen, 21% oxygen, 0.27: 1 volume ratio of oxygen and nitrogen) and gas diluted with nitrogen (97% nitrogen, 3% oxygen, 0.03: 1 volume ratio of oxygen and nitrogen) The regeneration time was 60 hours, the jacket heat source feeder (6) was heated to 200 ℃ 2 ℃ / min and maintained at 8.3 ℃ 400 ℃, 49.6 hours at 450 ℃. The dehydrogenation reaction was carried out on the regenerated catalyst in the same manner as in Example 1, and the conversion and selectivity were confirmed every 12 hours by GC, and the results were obtained as shown in Table 4 at 10-day intervals.

Use of catalyst
term New catalyst Nitrogen: Oxygen = 79%: 21% Nitrogen: Oxygen = 97%: 3% Conversion rate Selectivity Conversion rate Selectivity Conversion rate Selectivity 1 day 99% 100% 99% 100% 99% 100% 10 days 97% 100% 98% 100% 97% 98% 20 days 96% 100% 97% 100% 98% 99% 30 days 97% 98% 94% 96% 93% 95% 40 days 93% 99% 89% 92% 90% 91% 50 days 92% 96% 88% 90% 86% 89% 60 days 90% 93% 85% 89% 83% 88% 70 days 88% 91% 80% 84% 80% 83% 80 days 85% 88% 78% 79% 76% 77% 90 days 80% 83% 74% 77% 71% 72% 100 days 76% 80% 67% 72% 64% 70% 110 days 70% 74% 55% 68% 56% 65% 120 days 62% 65% 48% 60% 47% 57%

According to Table 4, as the oxygen source used to oxidize the coke on the surface of the catalyst, the conversion and selectivity are similar in the case of using oxygen-diluted gas and nitrogen regeneration.

2 and 3 are graphs showing the temperature change in the reactor according to the set temperature of the heat source supply device when using a gas diluted with oxygen and nitrogen, and the temperature at which the coke on the catalyst surface is removed. And the temperature at which the coke accumulated in the catalyst pores is removed. As shown in FIG. 2, when a gas diluted in nitrogen is used, a sudden temperature change does not occur, so temperature control inside the reactor is easy, whereas when using air as shown in FIG. 3, a sudden temperature change occurs to control the internal temperature. Was difficult.

Therefore, in the case of using oxygen-diluted gas in nitrogen during regeneration of the catalyst, it is similar to air in conversion and selectivity, but for the internal temperature control and stability of reaction, it is more preferable to use gas diluted in oxygen in nitrogen. It can be seen.

1 is a schematic diagram of a device capable of regenerating a catalyst with dehydrogenation of 1,5-DMT to 1,5-DMN.

2 is a temperature change curve with time when regenerating a catalyst using a gas diluted with oxygen in nitrogen.

3 is a temperature change curve with time when regenerating a catalyst using air.

1: 1,5-DMT storage tank 2: 1,5-DMT injection pump

3: gas inlet port 4: dehydrogenation fixed bed reactor

5: reactor internal thermometer 6: jacket heat source supply device

7: pressure gauge 8: 1,5-DMN storage tank

9: capture drum 10: activated carbon bed (Bed)

Claims (5)

In the regeneration of the catalyst in a reaction process in which a hydrocarbon having a ring structure of 11 or more carbon atoms is dehydrogenated and converted into an aromatic compound of the same ring by using an alumina catalyst loaded with tin (Sn) and platinum (Pt), Oxidizing and burning the coke attached to the catalyst surface by injecting oxygen-diluted gas into nitrogen having a volume ratio of oxygen to nitrogen at a temperature of 400 to 600 ° C. of 0.03: 1 to 0.27: 1; Removing the reactant of oxygen and coke and drying the catalyst; Regeneration method of alumina catalyst loaded with tin (Sn) and platinum (Pt), characterized in that it comprises the step of reducing the catalyst with hydrogen at 200 ~ 400 ℃ temperature. The method of regenerating an alumina catalyst loaded with tin (Sn) and platinum (Pt) according to claim 1, wherein the oxidation temperature is 450 to 550 ° C. delete The method of regenerating an alumina catalyst loaded with tin (Sn) and platinum (Pt) according to claim 1, wherein the regeneration time of the catalyst is 60 hours or more. The method of claim 1, wherein the hydrocarbon having a ring structure having 11 or more carbon atoms is 1,5-dimethyltetraline, and the aromatic compound of the same ring is 1,5-dimethylnaphthalene (Sn) and platinum ( Regeneration method of alumina catalyst loaded with Pt).

Images