KR20040004799A - coproduction of hydrogen and carbon black by thermal decomposition of methane - Google Patents

Abstract

PURPOSE: A method for the co-production of hydrogen and carbon black by thermal cracking of natural gas without emitting carbon dioxide is provided. CONSTITUTION: The method comprises the steps of introducing natural gas such as methane into a tubular reactor(11); heating the natural gas at 1100 to 1200 deg.C, and separating hydrogen gas using a hydrogen-methane separator(12) such as membrane filtration or adsorption process, wherein the retention time of the natural gas in the reactor is about 0.3 to 0.5 sec.

Description

Production method of hydrogen and carbon black by thermal decomposition of methane

The present invention relates to a method of simultaneously producing hydrogen and carbon black without generating carbon dioxide by pyrolyzing natural gas (methane), and more particularly, by using a part of hydrogen generated in pyrolysis as a heat source, The present invention relates to a method of simultaneously producing hydrogen and carbon black from natural gas without generating any carbon dioxide.

Hydrogen energy has emerged as the only solution that can solve both energy and environmental problems of the 21st century at the same time, and research on manufacturing, storage and use is actively conducted worldwide.

Hydrogen is estimated to be produced from water using alternative energy including solar energy rather than from fossil fuels such as coal and natural gas without generating carbon dioxide, but at present it is questionable that it can be produced on an economically useful scale. The level of technology is also within the basic research stage. Therefore, hydrogen is expected to be produced from natural gas for some time to come.

There are several known methods for producing hydrogen from natural gas, including steam reforming. However, existing methods do not provide a fundamental solution to the global warming problem because a large amount of carbon dioxide is generated at the same time.

From this point of view, the process of producing hydrogen by pyrolysis of natural gas does not generate carbon dioxide, so it does not cause global warming problems, and has reached a technical level that can be produced in large quantities even when compared with steam reforming. There is an advantage obtained as a byproduct.

The technique of producing hydrogen by directly decomposing natural gas includes plasma decomposition, which has been studied a lot, and is being commercialized in some countries including Norway.

However, there are technical difficulties to be solved to enlarge the size and power consumption is high, so there is no economical in the country where the power bill is expensive, even if it is inevitable to release carbon dioxide in power generation, it is not free from environmental problems. Therefore, it is a useful method only in some countries, such as Norway, which generate electricity by hydropower.

Another technique for decomposing natural gas to produce hydrogen is to use a catalyst. Catalytic decomposition has a relatively low reaction temperature compared with pyrolysis, but has a problem in that carbon produced as a by-product is deposited on the catalyst and thus the catalytic activity falls within a short time.

An object of the present invention is to provide a method for simultaneously producing hydrogen and carbon black from natural gas by pyrolysis without generating carbon dioxide.

1 is an example of an apparatus configuration suitable for the practice of the present invention in the case of burning a part of the produced hydrogen.

Explanation of symbols on the main parts of the drawings

11: pyrolysis reactor 12: hydrogen / methane separator

13: burner

The present invention for achieving the above object is characterized in that the pyrolysis of natural gas (methane) at a temperature of 950 ~ 1300 ℃.

Natural gas (methane) is decomposed into carbon black and hydrogen at high temperature as shown in [Scheme 1], which is an endothermic reaction and requires about 75.6 kJ of energy per mole.

The pyrolysis reaction of the natural gas occurs at 950 ° C. or higher, but is preferably performed at 1,100 to 1,200 ° C. The reaction does not occur actively below 950 ℃, and when the temperature is over 1,300 ℃, the equipment cost increases because the reactor and the pipe must be made of a special material. Therefore, it is preferable to make reaction temperature into 1,100-1,200 degreeC.

The shape of the reactor is not particularly limited, but the use of a tubular reactor facilitates heat transfer and is advantageous for precisely controlling the reaction time.

The residence time of the natural gas in the reactor is preferably 0.5 to 3.0 seconds. Short residence times result in lower yields, too long yields reduced throughput.

In addition, as a heat source of a reactor for decomposing natural gas, heat generated by burning a part of hydrogen produced may be supplied. According to this method, hydrogen may be produced without generating carbon dioxide at all stages.

Hydrogen generated in the reactor can be purified to high purity through known methods such as membrane separation or adsorptive separation. Carbon black obtained as a by-product can be usefully used for various purposes such as tires and inks.

The structure of this invention is demonstrated more concretely using FIG. 1 which shows an example of the apparatus structure suitable for implementation of this invention in the case of burning a part of produced hydrogen.

When natural gas (methane) is supplied to the pyrolysis reactor (11), it is pyrolyzed in the pyrolysis reactor, and then flows into the hydrogen / methane separator (12) to separate hydrogen and methane. The methane is recycled and pyrolyzed together with the raw natural gas again. Hydrogen is introduced into the reactor, and the produced hydrogen is discharged and stored in a storage device (not shown), which is supplied to the burner 13 to supply heat to the pyrolysis reactor. On the other hand, the carbon black produced in the pyrolysis reactor 11 is collected in a collector (not shown) at the bottom of the reactor.

The configuration of the present invention will be further clarified by the following embodiments, but the scope of the present invention is not limited by these embodiments.

<Example 1>

Methane gas was used as the sample gas, and an alumina tube having an outer diameter of 15 mm, an inner diameter of 9 mm, and a length of 1,200 mm was used.

Methane gas was injected into the reactor at a constant flow rate using a mass flow meter (MJ Tech., Model MR300) and a control valve (KOFLOC, Model No. 3660) .Methane gas passed through the mass flow meter was heated to 900 ° C before being injected into the reactor. Preheated.

In the reactor, hydrogen, carbon black, and unreacted methane gas produced by decomposition of methane gas were discharged. After reacting for 3 seconds at a temperature of 950 ° C, the hydrogen concentration of the exhaust gas was 11.4 mol%.

<Examples 2 to 32>

Using the same apparatus as in Example 1 was carried out by varying the reaction temperature and reaction time. The hydrogen concentration of the product is summarized in Table 1 together with Example 1.

division Reaction temperature (℃) Response time (seconds) Hydrogen concentration in the product (mol%) Example 1 950 3.00 11.4 Example 2 950 1.50 4.0 Example 3 950 0.67 2.0 Example 4 950 0.50 1.6 Example 5 1000 3.00 38.1 Example 6 1000 1.50 18.0 Example 7 1000 0.67 5.8 Example 8 1000 0.50 2.5 Example 9 1050 3.00 68.3 Example 10 1050 1.50 59.5 Example 11 1050 0.67 22.6 Example 12 1050 0.50 7.0 Example 13 1100 3.00 79.5 Example 14 1100 1.50 71.4 Example 15 1100 0.67 53.7 Example 16 1100 0.50 26.0 Example 17 1150 3.00 86.5 Example 18 1150 1.50 80.0 Example 19 1150 0.67 67.0 Example 20 1150 0.50 42.6 Example 21 1200 3.00 91.4 Example 22 1200 1.50 86.7 Example 23 1200 0.67 76.5 Example 24 1200 0.50 65.0 Example 25 1250 3.00 94.5 Example 26 1250 1.50 89.9 Example 27 1250 0.67 83.5 Example 28 1250 0.50 78.9 Example 29 1300 3.00 97.2 Example 30 1300 1.50 96.4 Example 31 1300 0.67 92.8 Example 32 1300 0.50 88.4

It can be seen from the above examples that the higher the reaction temperature and the longer the reaction time, the higher the yield of hydrogen. The hydrogen concentration of the exhaust gas is about 80% at 1,100 ° C., and the hydrogen concentration is 90% or more at 1,200 ° C. or higher.

According to the present invention, high purity carbon black can be produced simultaneously with hydrogen from natural gas without generating carbon dioxide.

Claims (4)

A method of simultaneously producing hydrogen and carbon black from natural gas, characterized by pyrolysing natural gas (methane) at a temperature of 950-1300 ° C. The method for producing hydrogen and carbon black simultaneously by pyrolysing natural gas according to claim 1, wherein the pyrolysis reaction temperature is 1,100 to 1,200 占 폚. The method for producing hydrogen and carbon black simultaneously by pyrolysing natural gas according to claim 1, wherein the residence time of the natural gas in the reactor is 0.5 to 3.0 seconds. A method of simultaneously producing hydrogen and carbon black by thermally decomposing natural gas, wherein a part of hydrogen produced as a heat source for decomposing natural gas is combusted.