JPH06305701A - Method for producing hydrogen from hydrocarbon and device therefor - Google Patents

Abstract

PURPOSE:To produce hydrogen from hydrocarbons in good yield by steam- reforming hydrocarbons, CO2-reforming the generated gas and the successively applying shift reaction of CO in the generated gas, CO2 removal and gas refining and recycling CO2. CONSTITUTION:Steam 11 is added to hydrocarbons 6, the mixture is introduced into a steam reformer 1, and a steam reforming reaction takes place. The gas 7 leaving the reformer 1 is introduced into a CO2 reformer 2 to bring about a CO2 reforming reaction. The gas 8 from the reformer 2 is subjected to high- temp. CO conversion and low-temp. CO conversion in a CO2 converter 3. The gas 9 from the converter 3 is introduced into a CO absorber 4 to separate and remove CO2. A requisite amt. 12 of the separated CO2 is circulated to the CO2 reformer 2, and the surplus CO2 13 is discharged. The gas 10 from the absorber 4 is introduced into a pressure-swing adsorber 5 and refined by pressure-swing adsorption. Pure hydrogen is recovered through a hydrogen recovery passage 14, and the impurities are discharged from a discharge passage 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing hydrogen from a hydrocarbon by a reforming reaction, and particularly, to obtain a highly pure hydrogen from a hydrocarbon oil such as kerosene, light oil, heavy oil, and vacuum residue in a high yield. A manufacturing method and apparatus.

[0002]

2. Description of the Related Art A method for producing hydrogen using hydrocarbon as a raw material is roughly classified into a steam reforming method and a partial oxidation method. The steam reforming method is a method in which a raw material hydrocarbon and steam are reacted at a high temperature in the presence of a catalyst. In the steam reforming method,
Since it is necessary to keep the activity of the catalyst stable over a long period of time, it is necessary to remove impurities in the raw material, and therefore hydrocarbons usable as a raw material are limited to hydrocarbons lighter than the naphtha fraction.

The partial oxidation method is a method in which a hydrocarbon is partially combusted with oxygen, and the residual hydrocarbon is reformed without a catalyst due to the high temperature and steam obtained by the combustion. Since the partial oxidation method does not use a catalyst, it is not affected by impurities in the raw material, and therefore not only light hydrocarbons but also heavy oil and coal can be used as raw materials.

Further, recently, it has been reported that hydrogen is produced from heavy oil by a hydrogen production method which is a combination of a steam reforming method and a partial oxidation method (for example, "Petrotech, Vol. 5, No. 12"). No. 89-90 (1982) "and" Proceed
ing of 11th World Petroleum Congress (1983) ").

As described above, conventional methods for producing hydrogen from hydrocarbons include a steam reforming method, a partial oxidation method, or a combination of these methods. In this case, the gas generated by the partial oxidation method has an H ₂ / CO ratio of about 50/50, whereas the gas generated by the steam reforming method is rich in hydrogen, and the steam reforming method uses the partial oxidation method. It has a feature that the amount of hydrogen generated per unit raw material is larger than that of

[0006]

As described above, the steam reforming method has an advantage that a hydrogen-rich generated gas is obtained and a large amount of hydrogen is obtained from a unit raw material. The present invention has been made in view of such a point, and a hydrocarbon by a reforming method incorporating a steam reforming method,
In particular, it is an object of the present invention to provide a method and an apparatus capable of producing hydrogen in good yield from hydrocarbon oil such as kerosene, light oil, heavy oil, and vacuum residue.

[0007]

Means for Solving the Problem and Its Action As a result of intensive research conducted by the present inventors to achieve the above object,
A two-stage reforming method is employed in which steam reforming of raw material hydrocarbons is carried out in the first stage, and carbon dioxide reforming of the product gas in the first stage is carried out in the second stage, and carbon monoxide in the product gas is further provided in the subsequent stages. Shift reaction, separation and removal of carbon dioxide from the produced gas, and purification of the produced gas are carried out in sequence, and the carbon dioxide separated in the latter stage is circulated and used in the second stage carbon dioxide reforming step, whereby a unit raw material is obtained. It was found that the amount of hydrogen produced per hit, the recovery rate of hydrogen can be increased to produce hydrogen in a high yield, and the amount of carbon dioxide emission to the outside of the system can be reduced, and the present invention has been completed. It was

Therefore, the present invention provides the following steps (a) to
There is provided a method for producing hydrogen from a hydrocarbon, which comprises (f). (A) Steam reforming step in which steam is added to the raw material hydrocarbon to carry out a steam reforming reaction. (B) Carbon dioxide is added to the gas produced from the steam reforming step (a), and a reforming catalyst is brought into contact. Carbon dioxide reforming step for obtaining hydrogen-containing gas (c) The hydrogen-containing gas from the carbon dioxide reforming step (b) is brought into contact with a shift reaction catalyst to convert carbon monoxide contained in the hydrogen-containing gas into carbon dioxide. Shift reaction step for conversion (d) Carbon dioxide absorption step for obtaining hydrogen-containing gas by separating and removing carbon dioxide contained in the gas produced from the shift reaction step (c) (e) From the carbon dioxide absorption step (d) For recovering pure hydrogen by purifying the hydrogen-containing gas in step (f) Carbon dioxide circulation step for circulating the carbon dioxide separated and removed in the carbon dioxide absorption step (d) to the carbon dioxide reforming step (b)

The present invention also provides a hydrogen production device from hydrocarbons, which comprises the following components (1) to (6) as a device for carrying out the above method. (1) Steam reforming section for carrying out steam reforming reaction of raw material hydrocarbon (2) Carbon dioxide for carrying out carbon dioxide reforming reaction of produced gas generated in the steam reforming section (1) in the presence of a reforming catalyst Reforming section (3) Shift reaction section for carrying out shift reaction of hydrogen-containing gas produced in the carbon dioxide reforming section (3) in the presence of a shift reaction catalyst (4) Generation produced in the shift reaction section (3) Carbon dioxide absorption part for separating and removing carbon dioxide in gas (5) Hydrogen recovery part for purifying hydrogen-containing gas produced in the carbon dioxide absorption step (4) to recover pure hydrogen (6) Carbon dioxide absorption step Carbon dioxide circulation means for circulating the carbon dioxide separated and removed in (d) to the carbon dioxide reforming step (b)

The hydrogen production method of the present invention will be described in more detail below. In the steam reforming process of the first stage, the steam reforming reaction is performed by adding steam to the raw material hydrocarbon. As a result, a hydrocarbon gas mainly containing methane is usually produced. here,
As the raw material hydrocarbon, any hydrocarbon such as naphtha, kerosene, light oil, heavy oil, reduced pressure residue, methanol, etc. can be used, and particularly hydrocarbon oil such as kerosene, light oil, heavy oil, reduced pressure residue is effectively used. can do. The reaction conditions of the steam reforming reaction in this step are not limited, but usually the pressure of the raw material and steam is 1 to 10 kg / cm ² , preferably ² to 6 kg / c.
m ² , temperature 400 to 800 ° C., preferably 500 to 600
The reaction is conducted at a temperature of 0 ° C. and a steam / carbon ratio (mol / atomic ratio) of 1 to 6, preferably 2 to 3. Although a catalyst is not usually used, a catalyst obtained by adding an alkaline earth metal or the like to an alumina carrier may be used if necessary. A tubular reactor can be preferably used as the reaction device used in this step.

Carbon Dioxide Reforming Step In the second carbon dioxide reforming step, the carbon dioxide circulated from the carbon dioxide absorption step described below is added to the product gas from the first steam reforming step to reform the gas. A hydrogen-containing gas is obtained by contacting with a catalyst and reforming carbon dioxide. The reaction conditions of the carbon dioxide reforming reaction in this step are not limited, but in the presence of the reforming catalyst, the product gas from the steam reforming step and the carbon dioxide are usually at a pressure of 1 to 15.
kg / cm ^2, preferably 2~6kg / cm ^2, temperature 700 to 100
The reaction is performed at 0 ° C, preferably 800 to 1000 ° C. The circulating amount of carbon dioxide from the carbon dioxide absorption step is 1 to 5 moles, preferably 3 to 4 moles, relative to 1 mole of the produced gas from the steam reforming step. As the reforming catalyst, it is possible to use a known catalyst, for example, a support made of SiO ₂ on which a metal such as Ni, Rh or Ru is supported by about 5% by weight by an ordinary method such as an impregnation method. Prior to use, the catalyst was heated at 500-800 ° C. for 5-6 hours to remove H ₂ O and H ₂ (H _2
The reduction treatment can be carried out with ₂ O / H ₂ = 6 mol). Further, the gas passing through the catalyst bed is GHSV500-2500.
It can be processed with h ⁻¹ . When a heavy oil containing a large amount of impurities such as a sulfur compound is used as a raw material, it is preferable to provide a desulfurization step for removing the sulfur compound after the first steam reforming step.

Shift Reaction Step In the shift reaction step, the shift reaction of carbon monoxide contained in the hydrogen-containing gas from the carbon dioxide reforming step is carried out in the presence of the shift reaction catalyst. As a result, carbon monoxide is transformed into carbon dioxide and hydrogen. In this step, the method of shift reaction is not particularly limited, but high temperature CO conversion and low temperature CO conversion
A two-stage metamorphism in which the metamorphism is sequentially performed can be preferably adopted. High temperature CO
In the transformation, the shift reaction is usually carried out under the conditions of a pressure of 10 to 40 kg / cm ² G, preferably 25 to 35 kg / cm ² G, and a temperature of 350 to 450 ° C., preferably 370 to 400 ° C. to change the CO concentration in the gas. Reduce to 2-4% by volume. The shift reaction catalyst used for high temperature CO shift conversion is usually an oxide of Fe or Cr. In low temperature CO shift, pressure is usually 10-40kg / c
m ² G, preferably 25 to 35 kg / cm ² G, temperature 190 to ²
The shift reaction is carried out under the conditions of 40 ° C., preferably 200 to 220 ° C., to reduce the CO concentration in the gas to 0.2 to 0.5% by volume. The shift reaction catalyst used for low temperature CO shift conversion is usually an oxide such as Cu-Zn. This Cu-Zn
Since the system catalyst is extremely sensitive to the influence of sulfur, it is desirable to remove hydrogen sulfide from the gas with a ZnO adsorbent or the like before introducing the gas into the low temperature CO shift process.

Carbon dioxide absorption step In the carbon dioxide absorption step, carbon dioxide is separated and removed from the product gas generated in the shift reaction step to obtain a hydrogen-containing gas. As the carbon dioxide removing means in this step, the MEA method, the hot potassium carbonate method or the like is usually adopted. The MEA method absorbs carbon dioxide using a 10 to 20% aqueous solution of monoethanolamine as an absorbing solvent. The hot potassium carbonate method is
Carbon dioxide is absorbed using a hot water solvent mainly composed of potassium carbonate as an absorbing solvent. In this step, the concentration of carbon dioxide in the gas generated in the carbon monoxide shift reaction step is 0.1 to 0.1%.
It is desirable to remove up to 0.5% by volume. Further, the carbon dioxide separated and removed in this step is circulated to the second-stage carbon dioxide reforming step and used for the carbon dioxide reforming reaction of the produced gas generated in the steam reforming step.

Hydrogen recovery step In this step, the hydrogen-containing gas produced in the carbon dioxide absorption step is purified to obtain pure hydrogen. The pressure fluctuation adsorption method (PSA method) is preferably adopted as the gas purification means in this step. In the pressure fluctuation adsorption method, gas purification is performed by using the difference in physical adsorption ability between hydrogen and other impurities with respect to the adsorbent. Usually, a gas purification apparatus using the pressure fluctuation adsorption method is composed of four or more adsorption towers, and molecular sieves or activated carbon is filled as an adsorbent in the towers. Impurities other than hydrogen in the gas are adsorbed by the adsorbent under high pressure to obtain high-purity hydrogen gas.

Carbon Dioxide Circulation Step In this step, the carbon dioxide removed in the carbon dioxide absorption step is circulated to the carbon dioxide reforming step. The circulated carbon dioxide is recycled and used in the carbon dioxide reforming process.

[0016]

The present invention produces hydrogen from hydrocarbons by a two-stage reforming reaction of a steam reforming reaction (first stage) and a carbon dioxide reforming reaction (second stage) using carbon dioxide produced in the system. It is manufactured. That is, the gas (hydrocarbon gas) generated in the first stage is reformed with carbon dioxide in the second stage as shown by the following formula C _m H _n + CO ₂ → CO + H ₂ to generate carbon monoxide. Is converted into carbon dioxide by a shift reaction as in the following formula CO + H ₂ O → CO ₂ + H ₂ , so that the amount of hydrogen produced increases. Moreover, since the generated carbon dioxide is separated and removed and circulated and used for the second-stage carbon dioxide reforming reaction, the hydrogen recovery rate is increased.

[0017]

EXAMPLES Next, the present invention will be illustrated concretely by examples, but the present invention is not limited to the following examples. Example FIG. 1 is a schematic configuration diagram showing an example of a hydrogen producing device from hydrocarbons according to the present invention. The hydrogen production apparatus of the present embodiment has a steam reforming apparatus (steam reforming section) 1, a carbon dioxide reforming apparatus (carbon dioxide reforming section) 2, a CO shift conversion apparatus (shift reaction section) from the upstream side to the downstream side. 3, a CO ₂ absorption device (carbon dioxide absorption part) 4 by the MEA method, and a pressure fluctuation adsorption device (hydrogen recovery part) 5 are sequentially provided.

A raw material introduction passage 6 is connected to the steam reforming apparatus 1, and gas transfer passages 7, 8, 9, 10 are provided between the respective apparatuses 1, 2, 3, 4, 5. Has been. Further, a steam introducing passage 11 is connected to the raw material introducing passage 6, and the CO ₂ absorbing device 4 and the carbon dioxide reforming device 2 are connected to the C ₂ between the CO ₂ absorbing device 4 and the carbon dioxide reforming device 2.
CO ₂ circulation path (carbon dioxide circulation means) for circulating O ₂ 12
Is provided. A discharge passage 13 is connected to the CO ₂ absorption device 4, and a hydrogen recovery passage 14 and a discharge passage 15 are connected to the pressure fluctuation adsorption device 5.

The carbon dioxide reforming apparatus 2 is filled with a reforming catalyst in which Ni, Rh, Ru, etc. are supported on a SiO ₂ carrier. The CO shift converter 3 is divided into a high temperature CO shift section in the front stage and a low temperature CO shift section in the rear stage, and the high temperature CO shift section is filled with oxides of Fe and Cr as shift reaction catalysts.
An oxide such as Cu-Zn is filled in the low-temperature CO shift converter as a shift reaction catalyst. In addition, the pressure fluctuation adsorption device 5
Is filled with molecular sieve as adsorbent

The production of hydrogen using the hydrogen production apparatus of this embodiment is carried out according to the following procedures. Steam is added to the hydrocarbons flowing through the raw material introducing passage 6 from the steam introducing passage 11, and the hydrocarbons and steam are introduced into the steam reforming apparatus 1 to perform a steam reforming reaction. The gas that has left the steam reforming device 1 is introduced into the carbon dioxide reforming device 2 through the gas transfer path 7, and the carbon dioxide reforming reaction is performed. The gas discharged from the carbon dioxide reformer 2 is introduced into the CO shift converter 3 through the gas transfer passage 8, and the high temperature CO shift and the low temperature CO shift are sequentially performed. The gas leaving the CO shift converter 3 passes through the gas transfer path 9 to C
It is introduced into the O ₂ absorber 4, and CO ₂ is separated and removed by the MEA method. The required amount of the separated and removed CO ₂ is recycled to the carbon dioxide reformer 2 through the CO ₂ circulation path 12. Excess CO ₂ is discharged from the discharge passage 13. The gas that has left the CO ₂ absorption device 4 is introduced into the pressure fluctuation adsorption device 5 through the gas transfer passage 10 and purified by the pressure fluctuation adsorption method. Pure hydrogen is recovered through the hydrogen recovery passage 14, and impurities are discharged through the discharge passage 15.

Next, an example of production by the hydrogen producing apparatus of this embodiment will be shown. Production Example Using reduced-pressure residual oil as a raw material hydrocarbon, steam reforming is performed in a steam reforming apparatus 1 under conditions of a pressure of 5.0 kg / cm ² G, a temperature of 600 ° C., and a steam / carbon ratio (mol / atom ratio) of 3.0. The reaction was carried out. The generated gas of the steam reforming apparatus 1 is sent to the carbon dioxide reforming apparatus 2, and the pressure is 5.0 kg / cm ² G and the temperature is 1000.
The carbon dioxide reforming reaction was carried out under conditions of ° C and carbon dioxide / produced gas (molar ratio) of 3.6. The CO ₂ circulated from the CO ₂ absorber 4 was used. The gas discharged from the carbon dioxide reforming apparatus 2 was sent to the CO shift converter 3, and first, high temperature CO shift and then low temperature CO shift were sequentially performed. High temperature CO shift is pressure 30
It was carried out under the conditions of kg / cm ² G and temperature of 400 ° C., and the low temperature CO shift was carried out under the conditions of pressure of 30 kg / cm ² and temperature of 200 ° C. The gas discharged from the CO shift converter 3 was sent to the CO ₂ absorber 4 to absorb and separate CO ₂ . Part of the separated CO ₂ was circulated to the carbon dioxide reformer 2. The gas discharged from the CO ₂ absorption device 4 was sent to the pressure fluctuation adsorption device 5 to adsorb and separate impurities other than hydrogen to obtain high-purity hydrogen gas.

The results of the above production examples are shown in Table 1 below. Table 1
Shows the material balance at a hydrogen production amount of 10,000 Nm ³ / hr. The symbols A to F in Table 1 indicate the following (see FIG. 1). A: Raw material introduction amount into the steam reforming device 1 B: Steam introduction amount into the steam reforming device 1 C: Carbon dioxide introduction amount into the carbon dioxide reforming device D D: Carbon dioxide emission amount from the discharge passage 13 E : Amount of pure hydrogen recovered from the pressure fluctuation adsorption device 5 F: Amount of exhaust gas from the pressure fluctuation adsorption device 5 From the results of Table 1, the hydrogen generation amount in this production example is 58.0 kg-mol per 1 kg of raw material, That is, it was found that it was 3,849 Nm ³ per 1 t of the raw material.

[0023]

[Table 1]

Comparative Example Table 2 shows an example of producing hydrogen by a partial oxidation method using heavy oil as a raw material (Petrotech, Vol. 4, No. 12, p. 27 (198).
1)) is shown. The amount of hydrogen produced by the same raw material (vacuum residue oil) as in the present invention is 2,604 Nm ³ / t, and it can be seen that the amount of hydrogen produced by the production example of the present invention is about 48% higher than that in the partial oxidation method.

[0025]

[Table 2]

Table 3 shows an example of producing hydrogen by combining the steam reforming method and the partial oxidation method using heavy oil as a raw material (Petrotech, Volume 5, No. 12, page 89 (1982)). The amount of hydrogen produced by the same raw material (vacuum residue oil) as in the present invention is 3,
033Nm ³ / t raw material, the production example of the present invention is about 27%
It can be seen that hydrogen production is large.

[0027]

[Table 3]

[0028]

As described above, the method for producing hydrogen from hydrocarbons and the apparatus for producing hydrogen according to the present invention are the two-stage reforming consisting of the first-stage steam reforming and the second-stage carbon dioxide reforming. Since the carbon dioxide generated in the system is circulated and used for the second stage carbon dioxide reforming, a large reforming effect can be obtained compared to the conventional method, and It has the advantages that the amount of hydrogen produced and the recovery rate of hydrogen can be increased to produce hydrogen with a high yield, and the amount of carbon dioxide discharged to the outside of the system can be reduced. Therefore, the hydrogen production method and the hydrogen production apparatus of the present invention can be effectively used for producing hydrogen from various hydrocarbons, particularly kerosene, light oil, heavy oil, reduced pressure residue, and other hydrocarbon oils.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a hydrogen production device of the present invention.

[Explanation of symbols]

1 steam reformer 2 carbon dioxide reformer 3 CO shifter 4 CO ₂ absorber 5 pressure fluctuation adsorption device 12 CO ₂ circulation path

Claims (2)

[Claims] 1. A steam reforming step of (a) adding steam to a raw material hydrocarbon to carry out a steam reforming reaction, and (b) adding carbon dioxide to the gas produced from the steam reforming step (a). A carbon dioxide reforming step of contacting a reforming catalyst to obtain a hydrogen-containing gas; and (c) contacting the hydrogen-containing gas from the carbon dioxide reforming step (b) with a shift reaction catalyst to obtain the hydrogen-containing gas. A shift reaction step of converting the contained carbon monoxide into carbon dioxide, and (d) a carbon dioxide absorption step of separating and removing carbon dioxide contained in the product gas from the shift reaction step (c) to obtain a hydrogen-containing gas. (E) a hydrogen recovery step of purifying the hydrogen-containing gas from the carbon dioxide absorption step (d) to obtain pure hydrogen, and (f) the carbon dioxide separated and removed in the carbon dioxide absorption step (d) as the carbon dioxide. Cycle to carbon reforming process (b) A method for producing hydrogen from hydrocarbons, which comprises a step of circulating carbon dioxide. 2. A steam reforming section for performing a steam reforming reaction of a raw material hydrocarbon, and (2) a carbon dioxide reforming reaction of a product gas produced in the steam reforming section (1) as a reforming catalyst. (4) a carbon dioxide reforming section for carrying out the shift reaction of the hydrogen-containing gas produced in the carbon dioxide reforming section (3) in the presence of a shift reaction catalyst, and (4) A carbon dioxide absorption part that separates and removes carbon dioxide from the product gas generated in the shift reaction part (3), and (5) the hydrogen-containing gas generated in the carbon dioxide absorption step (4) is purified to obtain pure hydrogen. It is characterized by comprising a hydrogen recovery unit for recovering and (6) carbon dioxide circulating means for circulating the carbon dioxide separated and removed in the carbon dioxide absorption step (d) to the carbon dioxide reforming step (b). Hydrogen production equipment from hydrocarbons.