KR101016669B1 - Apparatus for alkane dehydrogenation using microwave energy - Google Patents

Abstract

The present invention relates to a device for dehydrogenating alkanes of C4 or less, that is, light saturated hydrocarbons (Alkane). More specifically, instead of the conventional thermal cracking method, microwaves and their absorption and catalytic functions are simultaneously used. The present invention relates to an alkane dehydrogenation apparatus using microwaves for producing alkenes or olefins from hard alkanes using so-called dielectric catalysts.

Microwave, dielectric catalyst, alkanes, dehydrogenation, alkenes, olefins

Description

Alkanes dehydrogenation apparatus using microwaves {Apparatus for alkane dehydrogenation using microwave energy}

The present invention relates to a device for dehydrogenating alkanes of C4 or less, that is, light saturated hydrocarbons (Alkane). More specifically, instead of the conventional thermal cracking method, microwaves and their absorption and catalytic functions are simultaneously used. Alkene or olefin is prepared from light alkanes using a complex having so-called dielectric catalysts.

Olefin is an essential basic raw material for almost all petrochemical products and is usually produced by pyrolysis of naphtha or C2 or higher hydrocarbons. In particular, C2 or higher hydrocarbon pyrolysis technology is currently being operated commercially by Union Carbide Corp.'s Ethoxene process and UOP's Oleflex process.

However, this pyrolysis method is very difficult to activate due to the strong CH bond energy of the hard alkanes themselves, as shown in Table 1, requires a high reaction temperature and energy consumption of 700 ~ 850 ℃, thermodynamic equilibrium of the pyrolysis reaction Due to constraints, they are operating at relatively low alkane conversions of 60-65%.

hydrocarbon CH binding energy
(kJ / mol) Atomic charge
on H CH ₄ 440 +0.087 C ₂ H ₆ 420 +0.002 C ₃ H ₈ 401 -0.051 iso-C ₄ H ₁₀ 390 -0.088

In addition to the basic problems of reaction thermodynamics, these commercial processes are frequently shut down to prevent caulking and pressure drop due to the use of special furnaces for high temperature operation and the use of thin, long tubular reactors of about 100 m (approximately 45 days). ) And high facilities investment costs, including additional facilities such as insulation due to bulk heating.

Recently, oxidative or catalytic dehydrogenation technology, dehydrogenation technology combined with hydrogen combustion, membrane reaction or plasma reaction technology have been researched and developed to overcome this traditional method, but there are no remarkable results.

In addition, in order to fundamentally solve the problem of the conventional heating method, the development of a chemical reaction technology using microwave heating, which has a completely new heat transfer mechanism, that is, the material itself absorbs microwaves and generates heat.

Such microwaves are a kind of electromagnetic waves having a frequency of 300 MHz to 30 GHz and a wavelength band of 0.1 to 1 m. Among them, microwave dielectric heating using ISM (Industry Science and Medicine) frequency has polarization molecules with a cycle conversion speed corresponding to the corresponding frequency. It is a heating method in which the material itself generates heat by using intermolecular friction energy by rotation of or rearrangement of molecules.

However, chemical reactions of most organic materials, especially gaseous organic compounds below C4, which are permeable to microwaves, cannot be reacted by exothermic heat of the reactants themselves. Therefore, a similar method to the sensitizer concept of photocatalytic reactions is required. That is, the development of a new complex, that is, a dielectric catalyst, capable of simultaneously functioning as an energy converter that absorbs microwaves and supplies energy for chemical reactions and a role as a chemical catalyst suitable for a target reaction is important.

The present invention has been made to solve the above problems, by overcoming the thermodynamic equilibrium constraint of the dehydrogenation technology of C4 or less according to the existing bulk gas heating by the selective internal rapid heating of the dielectric catalyst itself by microwave, To achieve high alkane conversion at temperature. In particular, it aims to develop a new dielectric catalyst that can maximize the catalytic properties of microwave itself, which greatly improves the reaction activity as the dispersion of solid surface charged particles in the electromagnetic field increases.

In addition, it minimizes the energy required for dehydrogenation of alkanes below C4 and improves the reaction rate by the characteristics of microwave catalyst and additional equipment required for separation and purification of products by natural rapid cooling of the product gas by selective heating of dielectric catalyst only. And another object is to provide a miniaturized dehydrogenation apparatus having a structure that can minimize the cost.

Dehydrogenation apparatus of the alkane according to the present invention for achieving the above object is a magnetron head is mounted on one side of the microwave generator, a waveguide is connected to one side of the micron head, the waveguide is filled with a dielectric catalyst And a feed gas inlet and a product gas outlet for introducing gas into the reactor, respectively, so that the carbonization reaction is performed in the introduced gas atmosphere.

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According to the present invention, it is possible to have a high alkane conversion rate at a relatively low temperature by overcoming the thermodynamic equilibrium constraint of the dehydrogenation technology of C4 or less according to the existing bulk gas heating by selective internal rapid heating of the dielectric catalyst itself by microwaves.

In addition, the energy required for dehydrogenation of alkanes below C4 is minimized, the reaction rate is improved by microwave catalytic characteristics, and the product gas is naturally rapidly cooled by selective heating of the dielectric catalyst alone. Minimize the equipment and costs.

In addition, since the device can be miniaturized compared to the conventional heating furnace, installation cost and space can be minimized.

Hereinafter, a method and apparatus for dehydrogenation of alkanes using microwaves according to the present invention will be described in detail.

First, according to the method and apparatus for dehydrogenation of alkanes using microwaves according to the present invention, alkanes are prepared from alkenes or olefins as shown in Scheme 1 by microwaves and a dielectric catalyst.

Hereinafter, a method for dehydrogenation of alkanes using microwaves according to the present invention will be described.

In the dehydrogenation method of alkal according to the present invention, the alkanes are prepared from alkenes or olefins by irradiating microwaves with a dielectric catalyst and gaseous alkanes in contact with the dielectric to dehydrogenate alkanes as shown in Scheme 1.

At this time, the gaseous alkanes preferably have 1 to 4 carbon atoms, but are not necessarily limited thereto.

The dielectric catalyst may be one or two or more selected from the group consisting of natural carbonaceous carbon materials, perovskite oxides and paramagnetic materials, and porous carbon materials, alumina, silica, and carbonization. One having one or two or more selected from the group consisting of silicon as a support may be used. In this case, palladium (Pd) or platinum (Pt) may be used as the transition metal, and the paramagnetic material may be a dielectric material well known as a strong absorber of microwaves, that is, iron oxide (Fe _e O ₃ ), magnesium oxide (MgO), Copper oxide (CuO) etc. can be used.

On the other hand, the microwave uses the Industry Science and Medicine (ISM) frequency in the frequency range of 300MHz to 30GHZ.

According to the dehydrogenation of alkanes according to the present invention, selective internal rapid heating of the dielectric catalyst itself is effected by microwaves, thereby overcoming the thermodynamic equilibrium constraints of the dehydrogenation technology of C4 or less according to conventional bulk gas heating. High alkane conversion was achieved at relatively low temperatures.

Hereinafter, the dehydrogenation apparatus 10 of miniaturized alkanes for the dehydrogenation will be described with reference to FIG. 1.

The dehydrogenation apparatus 10 according to the present invention includes a microwave generator 20, a magnetron head 30, a waveguide 40, and a reactor 50.

The magnetron head 30 is mounted on one side of the microwave generator 20, and the waveguide 40 is installed on one side of the magnetron head 30.

At this time, the waveguide 40 is formed with a reactor 50 filled with a dielectric catalyst, and a supply gas inlet 43 for introducing gas into the reactor 50 is additionally installed in the waveguide 40. In addition, a product gas outlet 44 is formed on the opposite side of the feed gas inlet 43 to discharge the gas generated through the reaction.

In addition, the waveguide 40 is preferably bent in a 'c' shape by the first curved portion 41 and the second curved portion 42. The reactor 50 is installed between the first curved portion 41 and the second curved portion 42 of the waveguide 40, and the product gas outlet 44 is formed in the first curved portion 41. The supply gas inlet 43 is formed in the second valley 42 to allow alkanes to react between the first valley 41 and the second valley 42.

That is, the microwave generator 20 equipped with the magnetron head 30 generates microwaves, and the generated microwaves are moved through the waveguide 40 and supplied from the reactor 50 installed in the waveguide 40. Dehydrogenation reaction with the alkan gas flowing through the gas inlet 43, the alken gas generated through the dehydrogenation is discharged through the product gas outlet 44.

In this case, in order to prevent overheating of the magnetron head 30 due to the reflected power, the first dummy rod 61 and the impedance matching tutor 70 are sequentially disposed between the magnetron head 30 and the first curved portion 41. A directional attenuation coupler 80 is installed between the second curved portion 42 and the end of the waveguide 40, and a second dummy rod 62 is disposed at the end of the waveguide 40. Is installed.

That is, the reflected power of the microwaves that are not absorbed in the reactor 50 is attenuated through the bidirectional attenuator 80, and the reflected power of the microwaves passing through the bidirectional attenuator 80 is the second dummy rod 62. The reflected power of the microwaves absorbed by the second dummy rod 62 and not absorbed through the second dummy rod 62 will react in the reactor 50 again. Is absorbed through the impedance matching tutor 70 and the first dummy rod 61.

In this case, in order to prevent overheating of the second dummy rod 62, the circulating water may flow outside the end of the waveguide 40 in which the second dummy rod 62 is installed, and in the bidirectional attenuator 80, By further combining the microwave power meter 90 to measure the absorption power of the microwave in the reactor 50, the incident power of the microwave generator 20 may be adjusted.

In addition, a quartz reactor is used as the reactor 50, and the microwave generator 20 uses 2.45 GHz, which is an ISM (Industry Science and Medicine) frequency, in the frequency range of 300 MHz to 30 GHz, and has a frequency of 0 to 2.5 kW. It is desirable to have an incident power control range, but it is not necessarily limited thereto.

As described above, the dielectric catalyst may be one or two or more selected from the group consisting of natural coal-based carbon material, perovskite structure oxide and paramagnetic material, or porous carbon material and alumina. , And one having two or more kinds of mixtures selected from the group consisting of silica and silicon carbide (SiC) supporting a transition metal may be used.

Hereinafter, the present invention will be described in detail through experiments.

Dehydrogenation of alkanes using ISM frequency is applicable to various reactor types, such as fixed bed, fluidized bed, moving bed reactors or tubular, plate, microchannel, honeycomb, etc. In the present invention, the microwave absorption and reaction experiments were performed in the incident power range of 600 to 800 Watts while flowing nitrogen or reaction gas ethane at a speed of 200 cm 3 / min using a 2.45 GHz microwave generator.

Microwave absorption experiments carried out in a nitrogen atmosphere are based on the well-known microwave absorber alpha-silicon carbide (α-SiC) iron oxide (Fe _e O ₃ ), copper oxide (CuO), carbonaceous materials are domestic anthracite ( microwave for aluminum (γ-Al ₂ O ₃ oxide) - Korean Anthracite from Kyungdong Co.) and US FMC corp of coal char (FMC-char), and conventional thermal chemical support to the catalyst to be used primarily gamma:. KAK-A2 Absorption rate was measured. And the results are shown graphically in FIG.

As can be seen in Figure 2 carbonaceous materials domestic anthracite coal (KAK-A2) and US coal-based char (FMC-char) is a very good microwave absorber compared to paramagnetic materials alpha-silicon carbide, iron oxide, copper oxide, etc. It was confirmed that the gamma-aluminum oxide used as an existing catalyst support had a very low absorption rate.

In addition, microwave absorption rates were measured and compared with various coal-based carbonaceous materials, and the results are shown in FIG. 3. (KAK shown in FIG. 3 is the anthracite coal of the Kyungdong coal mine, M is the Maro coal mine, H is Hanbo coal mine, S is Samcheok coal seat, J is Jangseong coal mine, CAD is Dandong coal mine in China, and IAR is the Indonesian Rototan sample. Is denoted randomly by sampling numbering.)

As can be seen in FIG. 3, the microwave absorption characteristics of the porous activated carbon (Calgon-01) of the US Calgon Carbon corp., Which has a high degree of carbonization and a very high specific surface area, are extremely high, whereas lignite carbonaceous material having a low degree of carbonization (CAD-A1) , IAR-A1) show very low microwave absorption characteristics and relatively good absorption rate for domestic anthracite coal (KAK-E1, KAM-A3, KAH-A1, KAS-A1, KAJ-A1) with high carbonization but few pores. It was confirmed to have.

And the change in microwave absorption rate according to the average particle size of the powder for the domestic anthracite coal (KAK-A2) was measured, and the results are shown in FIG. As can be seen in Figure 4, it showed a significant difference in absorption rate according to the average particle size and showed the highest microwave absorption characteristics at a size of 0.25mm.

Based on the above experimental results, the experiment of ethane dehydrogenation using microwave of 700watts incident power was performed at the space velocity of 700hr-1. The results were as shown in Table 2 below.

(* Is repeated secondary experiment to confirm reproducibility)

As can be seen in Table 2, the conventional catalysts carrying palladium (Pd) or platinum (Pt) on gamma-aluminum oxide have very low reactivity, whereas alpha-silicon carbide, which is an excellent absorber of microwaves, is used as a support. Catalysts carrying palladium or platinum have a relatively high conversion of ethane and ethylene selectivity.

Particularly noteworthy results showed that the domestic anthracite coal (KAK-A2) as raw material without any catalyst such as palladium or platinum can obtain the highest ethylene yield with very high conversion and selectivity. In the case of the US-based coal char (FMC-char), which showed the highest microwave absorption rate, the conversion of ethane was the highest but the ethylene selectivity was relatively low.

In addition, the industrial and ash analysis of domestic anthracite coal (KAK-A2) as raw material showing the excellent dehydrogenation reaction of ethane was carried out and the results are shown in Table 3 below.

As can be seen in Table 3, it is seen as a unique microwave dielectric catalyst characteristic of domestic anthracite coal, which has a lower fixed carbon (FC) content and a higher ash content than general high calorie coal or US coal-based char (FMC-char). The results of ash analysis of did not determine which specific component and perovskite promoted the microdehydrogenation reaction.

In addition, experiments were conducted on the dehydrogenation of ethane with microwave incident power at a space velocity of 694 / h in a quartz reactor (inner diameter of 20 mm) filled with domestic anthracite (KAK-A2) powder with an average particle size of 1.705 mm as a microwave dielectric catalyst. The results are shown in FIG. 5.

As can be seen in Figure 5, the conversion of the highest ethane at about 700Watts, it was found that even after the incident power increase, the overall change in ethylene yield is not large.

In addition, the dehydrogenation reaction characteristics of ethane according to the average particle size of domestic anthracite coal were tested when the microwave incident power was 800 Watts under the same reaction conditions, and the results are shown in FIG. 6. As shown in FIG. 6, in the case of 0.25 mm having the highest microwave absorption characteristics, the conversion of ethane is close to 100%, but the ethylene selectivity is relatively low, resulting in low ethylene yield. As the particle size increases, the conversion decreases but the ethylene selectivity increases. It can be seen that the yield increases according to.

1 is a schematic diagram showing an apparatus for dehydrogenation of alkanes using microwaves according to the present invention.

Figure 2 is a comparison of the microwave absorption of the paramagnetic material and coal-based carbon material for α-SiC.

3 is a graph showing microwave absorption characteristics of coal-based carbon materials.

Figure 4 and graph showing the microwave absorption characteristics according to the average particle size of the domestic anthracite coal

5 is a graph showing the dehydrogenation performance of ethane according to microwave incident power

6 is a graph showing the dehydrogenation performance of ethane according to the average particle size of domestic anthracite coal

<Explanation of symbols for the main parts of the drawings>

10: microwave dehydrogenation apparatus 20: microwave generator

30: magnetron head 40: waveguide

41: first valley 42: second valley

43: supply gas inlet 44: product gas outlet

50: reactor 61: first pile load

62: second dummy rod 70: impedance matching tuner

80: bidirectional attenuator

90: microwave power meter

Claims (9)

delete delete delete delete delete In the dehydrogenation apparatus of alkanes using microwaves, The magnetron head 30 is mounted on one side of the microwave generator 20, the waveguide 40 is installed on one side of the micron head 30, and the reactor 40 is filled with a dielectric catalyst in the waveguide 40. ) And a feed gas inlet 43 and a product gas outlet 44 for introducing a gas into the reactor 50 are formed so that the dehydrogenation reaction of the introduced alkanes is performed. Dehydrogenation device. The method of claim 6, The waveguide 40 is bent in a 'c' shape by the first curved portion 41 and the second curved portion 42, and has a first dummy rod between the magnetron head 30 and the first curved portion 41. 61) and the impedance matching tudor 70 are sequentially installed, The reactor 50 is installed between the first curved portion 41 and the second curved portion 42, the product gas outlet 44 is formed in the first curved portion 41, and the second curved portion ( 42, a feed gas inlet 43 is formed, The bidirectional attenuator 80 is installed between the second curved portion 42 and the end of the waveguide 40, and a second dummy rod 62 is installed at the end of the waveguide 40. Alkaline dehydrogenation apparatus. The method according to claim 6 or 7, The dielectric catalyst is a dehydrogenation apparatus of alkanes using microwaves, characterized in that at least one selected from the group consisting of natural carbon-based carbon material, perovskite structure oxide and paramagnetic material. The method according to claim 6 or 7, The dielectric catalyst is a dehydrogenation apparatus for alkane using microwaves, characterized in that the support metal is supported by one or two or more selected from the group consisting of porous carbon materials, alumina, silica and silicon carbide.

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