JPH01259088A - Steam reforming of hydrocarbon - Google Patents

Abstract

PURPOSE:To remarkably prolong the life of a catalyst and decrease the necessary amount of steam, by treating a hydrocarbon with a higher-order desulfurizing agent and carrying out steam reforming, thereby effectively preventing the sulfur-poisoning of the steam reforming catalyst and the deposition of carbon. CONSTITUTION:A hydrocarbon is desulfurized with a higher-order desulfurizing agent to a sulfur-content of <=5ppb (most preferably <=0.1ppb) and subjected to steam reforming. The higher-order desulfurizing agent can be produced, e.g., by preparing a mixture of copper oxide, zinc oxide and aluminum oxide prepared from a copper compound, a zinc compound and an aluminum compound by the coprecipitation process and reducing the resultant mixture with hydrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for steam reforming of highly desulfurized hydrocarbons.

Prior art and its problems A typical desulfurization method conventionally used prior to steam reforming of hydrocarbons involves hydrogenation of organic sulfur in hydrocarbons in the presence of a Ni-Mo or Co-Mo catalyst. After disassembling
This is a method of removing generated H2S by adsorbing it onto ZnO.

However, such conventional methods have many problems. In other words, in the hydrodesulfurization process, if the hydrocarbon contains more than a certain amount of organic sulfur, especially difficult-to-decompose organic sulfur such as thiophene, undecomposed substances slip and are adsorbed onto ZnO. Pass by without being affected. In addition, for adsorption desulfurization, for example, Z n O + H2S: Z n S + H20Z
Due to the equilibrium represented by nO+CO8:ZnS+CO2, the amounts of H2S, CO8, etc. do not fall below a certain value. This tendency is particularly pronounced when H2O and CO2 are present.

Furthermore, if the desulfurization system is unstable during startup or shutdown of the device, sulfur may be scattered from the hydrodesulfurization device and the adsorption desulfurization catalyst, increasing the sulfur concentration in the purified product. Therefore, in the desulfurization step in the current steam reforming process, the sulfur concentration in the refined hydrocarbons ranges from several ppm to 0.5 ppm. There is no choice but to manage it at a level such that it becomes lppm.

The hydrocarbons desulfurized as described above are then treated with Ru
It is subjected to steam reforming in the presence of a catalyst such as Ni-based or Ni-based catalyst. However, McCarty at a
l ; J, Chem, Phys, vol 72.
No. 12゜6332.1980: J, Chem, P
hys, vol 74. No, IO, 5877, 19
81), the sulfur adsorption power of Ni and Ru is strong, so even if the amount of sulfur contained in the hydrocarbon is extremely small, most of the catalyst surface will be covered with sulfur. be exposed. Specifically, under the inlet conditions of a typical steam reforming process (near 450°C), the current best level of sulfur content ff10. At about lppm,
Approximately 90% of the surface of Ni or RU catalyst is covered by sulfur.
It will be covered within a short time. This means that current hydrocarbon desulfurization levels cannot prevent sulfur poisoning of the catalyst in the steam reforming process.

In consideration of such problems, Japanese Patent Laid-Open No. 17003/1983 proposes a steam reforming method using hydrocarbons desulfurized to 0.5 ppm or less. however,
In the method described herein, the degree of desulfurization of hydrocarbons is insufficient, it is not possible to sufficiently prevent poisoning of the steam reforming catalyst, and, as will be described later, it is not possible to reduce the amount of steam used.

Means for Solving the Problems As a result of extensive research in view of the current state of the technology as described above, the inventor of the present invention has determined that the sulfur content in the hydrocarbons subjected to steam reforming should be reduced to 5 ppb or less, more preferably. When the level is set to a low level of 1 ppb or less, more preferably 1 ppb or less, it is possible not only to substantially prevent sulfur poisoning of the steam reforming catalyst but also to prevent carbon precipitation on the catalyst. I found out.

That is, the present invention relates to a method for steam reforming hydrocarbons, which comprises desulfurizing the hydrocarbons to a sulfur content of ff15 ppb or less using a high-order desulfurization agent, and then steam reforming the hydrocarbons.

It has been well known that sulfur poisoning is the main cause of deterioration of steam reforming catalysts. However, if the sulfur content in the hydrocarbons subjected to steam reforming is 5 ppb or less,
More preferably 1 ppb or less, even more preferably O,1
The fact that not only sulfur poisoning but also carbon precipitation can be prevented by reducing the amount to ppb or less is a new finding that could not have been predicted in the past. Therefore, according to the method of the present invention, in the steam reforming of hydrocarbons, low steam ratio operation, low hydrogen ratio operation, and light It becomes possible to operate using heavy hydrocarbon raw materials such as light oil fractions. As a result, the economics of the steam reforming process is greatly improved.

The present invention will be described in more detail below with reference to the flowcharts shown in the drawings.

FIG. 1 shows an embodiment of the method of the present invention using a hydrocarbon having a total sulfur compound content of 10 ppm or less (as sulfur: hereinafter referred to) as a raw material. In this case, the raw material is subjected to a desulfurization step to reduce the sulfur content to 5 ppb or less, more preferably 1 ppb or less, and even more preferably 0.1 ppb or less (hereinafter referred to as higher desulfurization). The means for performing such high-order desulfurization is not particularly limited as long as it can reduce the sulfur content in the hydrocarbon to 5 ppb or less, preferably 1 ppb or less, more preferably 0.1 ppb or less, For example, a method of adsorption to a copper-based desulfurization agent, a silver thread desulfurization agent, a ruthenium-based desulfurization agent, a nickel-based desulfurization agent, activated carbon, etc. can be adopted. More preferably, Japanese Patent Application No. 62-279867 and Japanese Patent Application No. 6
Copper-zinc-based and copper disclosed in No. 2-279868
A desulfurization method using a zinc-aluminum desulfurization agent is mentioned. Such a desulfurizing agent is prepared by the method shown below.

(1) Copper-zinc desulfurization agent Aqueous solution containing copper compounds (e.g., copper nitrate, copper acetate, etc.) and zinc compounds (e.g., zinc nitrate, zinc acetate, etc.) and alkaline substances (e.g., sodium carbonate, potassium carbonate, etc.)
A precipitate is produced by a conventional coprecipitation method using an aqueous solution of. The generated precipitate is dried and calcined at about 300°C to form a copper oxide-zinc oxide mixture (in atomic ratio normal steel-zinc = 1: about 03-10, preferably 1: about 0.5-3, more preferably 1: about 1 to 2.3), diluted with an inert gas (e.g., nitrogen gas, etc.) so that the hydrogen content is 6% by volume or less, more preferably about 0.5 to 4% by volume. The above mixture is subjected to a reduction treatment at about 150 to 300°C in the presence of hydrogen gas. The copper-zinc desulfurization agent obtained in this manner may contain certain metal oxides, such as chromium oxide, as other carrier components.

(2) Copper-zinc-aluminum desulfurization agent Copper compounds (e.g., copper nitrate, copper acetate, etc.), zinc compounds (e.g., zinc nitrate, zinc acetate, etc.), and aluminum compounds (e.g., aluminum nitrate, sodium aluminate, etc.) and an aqueous solution of an alkaline substance (eg, sodium carbonate, potassium carbonate, etc.) to form a precipitate by a conventional coprecipitation method. The formed precipitate was dried and
It is fired at ℃ to form a copper oxide-zinc oxide-aluminum oxide mixture (at an atomic ratio of normal steel:zinc nialium=1:approximately 0).
．． 3-10: about 0.05-2, more preferably 1: about 0
．． 6-3: After obtaining about 0.3-1), the presence of hydrogen gas diluted with an inert gas so that the hydrogen content is 6% by volume or less, more preferably about 0.5-4% by volume. 15 below
The above mixture is subjected to a reduction treatment at about 0 to 300°C. The copper-zinc-aluminum desulfurization agent obtained in this way has
Certain metal oxides, such as chromium oxide, may also be included as other carrier components.

The copper-based desulfurization agent obtained by the methods (1) and (2) above is
Fine-particle copper with a large surface area is uniformly dispersed in zinc oxide (and aluminum oxide), and
It becomes highly active due to chemical interaction with zinc oxide (and aluminum oxide). Therefore, when using these desulfurization agents, the sulfur content in hydrocarbons can be ensured to be 5 ppb or less, if appropriate conditions are selected, 1 ppb or less, and under optimal conditions it can be easily reduced to 0.1 ppb or less. It is also possible to reliably remove refractory sulfur compounds such as thiophene.

In particular, copper-zinc-aluminum desulfurization agents have the advantage that they have excellent heat resistance due to the action of aluminum oxide, and can significantly reduce the decrease in strength and sulfur adsorption capacity at high temperatures. It will be done.

High-order desulfurization using the above copper-based desulfurization agent is usually carried out at a temperature of 200
~400℃, pressure 1~50kg/cTl・G,
It is carried out under conditions of about GH8V1000 to 5000.

FIG. 2 shows an embodiment of the method of the present invention using a hydrocarbon as a raw material having a total sulfur compound content of 10 ppm or more but a refractory organic sulfur compound content of less than 10 ppm. In this case, first, the raw material hydrocarbon is
It is subjected to primary adsorption desulfurization using a conventional method using an O-based desulfurization agent. The conditions at this time are not particularly limited, but in order to maximize the sulfur compound adsorption effect in the subsequent high-level desulfurization step, the sulfur content in the hydrocarbon is 1 to 0, 1.
It is desirable to reduce the amount to about ppm. Therefore,
- In the second adsorption desulfurization, it is preferable to adopt conditions such as temperature of about 250 to 400 degrees Celsius, pressure of about 10 kg/c/g, and GH of about 8V100O in the presence of a ZnO-based desulfurization agent, but other conditions may also be adopted. Of course, it is also possible. Next, the hydrocarbons that have undergone the -order adsorption desulfurization are sent to the same higher order desulfurization step as described above to reduce the sulfur content to 5 ppb or less, preferably 1 ppb or less, more preferably 0.1 ppb or less, and then steamed by a conventional method. Perform modification.

FIG. 3 shows an embodiment of the method of the present invention in which the raw material is a hydrocarbon containing 10 ppm or more of total sulfur compounds, mainly organic sulfur compounds that are difficult to decompose. In this case,
First, the raw material hydrocarbon is prepared using a conventional method such as Ni-
Mo-based, Co-M.

In the presence of a catalyst such as a system, the temperature is about 350 to 400℃, the pressure is 1
Hydrodesulfurization is performed under conditions of about 0 kg/cJ e G and about GH3V3000. Next, after primary adsorption desulfurization similar to that described in connection with FIG.
pb or less, more preferably O,1 ppb or less. At this time, since the hydrocarbons subjected to adsorption and desulfurization treatment are at a high temperature, it is preferable to perform high-order desulfurization using a copper-zinc-aluminum desulfurization agent having excellent heat resistance. The hydrocarbons subjected to high-order desulfurization are subjected to steam reforming using a conventional method.

Hydrocarbons used as raw materials in the present invention include:
Examples include natural gas, ethane, propane, butane, LPG (liquefied petroleum gas), light naphtha, heavy naphtha, light kerosene, coke oven gas, and various city gases.

Effects of the Invention According to the present invention, sulfur poisoning of the steam reforming catalyst and carbon deposition on the catalyst are extremely effectively prevented.
Catalyst life is greatly extended. Moreover, the required amount of water vapor can be reduced. That is, in conventional steam reforming methods, in order to operate for a long time, it was necessary to increase the S/C (number of moles of steam per mole of carbon in hydrocarbons) to 3.5 or more. , according to the method of the present invention, S/C is 0.
7 to 3.5, it is possible to operate stably for a long time.

EXAMPLES Below, reference examples, working examples, and comparative examples will be shown to further clarify the characteristics of the present invention.

Reference Example With current measurement techniques, it is difficult to directly measure ppb-order sulfur contained in combustible substances such as hydrocarbons. Therefore, in this specification, the measurement of ppb-order sulfur content in hydrocarbons is a value calculated based on the following method.

A patent application was made in 1982 for coke oven gas pre-purified by conventional methods.
High-order desulfurization was carried out using the copper-zinc-aluminum desulfurization agent disclosed in No. 279868.

The obtained high-order desulfurization coke oven gas was heated at 500ONi/hr.
2 wt 1% Ru/A Q 203 catalyst 3.
5 tons (bulk density 0.8 kg/R) was introduced into a reforming reactor (inner diameter 160 cmφ), and at an inlet temperature of 300°C.
The reforming reaction was carried out for 6000 hours.

The saturated poisoning amount of the catalyst used is Approximately 0.002 g-8/g-catalyst.

Ruthenium has an extremely high sulfur adsorption capacity, and if a high concentration of sulfur is present in the gas phase, it will adsorb it immediately.

Therefore, sulfur is present in a very thin layer on the surface of the catalyst layer (one layer from the surface layer).
It is thought that the particles are adsorbed at a depth of up to 0 cm.

Therefore, after the completion of the above reaction, 10 cm from the surface of the catalyst layer
Sulfur was analyzed by fluorescent X-ray analysis on the circumference up to m. The result was below the detection limit of sulfur (0,00005 g-8/g-catalyst) by fluorescent X-ray analysis. Therefore, the sulfur content contained in the highly desulfurized raw material gas was calculated using the following formula, and was found to be 0.1 ppb or less.

In the case of using LPG, naphtha, etc. other than coke oven gas, the sulfur content m was calculated using the same method.

Example 1 Naphtha containing 100 ppm of sulfur was first heated at 380° C. and at a pressure of 10 kg/cJ*cy in the presence of a Ni-Mo hydrodesulfurization catalyst according to a conventional method.

After hydrogenolysis under the conditions of LH8V2, hydrogen/naphtha-0.1 (molar ratio), contact with a ZnO-based adsorption desulfurization agent,
-Next adsorption desulfurization. The sulfur concentration in the obtained primary adsorption desulfurization naphtha was about 2 ppm.

On the other hand, sodium carbonate was added as an alkaline substance to a mixed aqueous solution in which copper nitrate, zinc nitrate, and aluminum nitrate were dissolved, and the resulting precipitate was washed and filtered. Molded into tablets, approximately 400
Calcined at ℃. Next, nitrogen gas containing 2% hydrogen was passed through a desulfurizer filled with 100 cc of the fired body (45% copper oxide, 45% zinc oxide, 10% aluminum oxide),
After reduction at a temperature of 200°C, the above obtained primary adsorption desulfurization naphtha was passed through 400 Q/hr at a temperature of 350°C.
High-order desulfurization was carried out under the condition of 1 pressure of 8 kg/cJ-G.

The sulfur concentration in the obtained high-order desulfurization naphtha was 0.1 ppb or less on average over 7000 hours of operation.

Next, using the obtained high-order desulfurized naphtha as a raw material, a flow-through pseudo-adiabatic reactor (diameter 20 mm) was used to conduct a second reaction in the presence of a ruthenium catalyst (ruthenium 2% by weight supported on a γ-alumina carrier). Methane was produced by performing low temperature steam reforming under the conditions shown in Table 1.

Table 1 Reaction temperature (inlet) 490°C (adiabatic) Reaction pressure 8 kg/c C/G naphtha flow rate
160cc/hr catalyst amount
100cc S/C1,7 H2/naphtha 0.1 (molar ratio) The results are shown in FIG. In FIG. 4, curve A-1 shows the temperature profile of the catalyst layer in the reactor immediately after the start of the reaction;
-2 shows the temperature profile of the catalyst layer in the reactor 400 hours after the start of the reaction.

According to the method of the present invention, even after 400 hours have passed, the reforming catalyst continues to maintain a sufficiently high activity, so that naphtha decomposition, which is an endothermic reaction, occurs at the inlet of the catalyst bed, just as it did immediately after the start of the reaction. The temperature then decreases, and the temperature rises due to subsequent exothermic reactions such as methanation and CO modification reactions.

Such a highly active state of the reforming catalyst is due to the amount of carbon deposited at each location on the catalyst after 400 hours (0.4% or less only at the reactor inlet) and the amount of sulfur deposited (at the reactor inlet). This is also supported by the detection limit of fluorescent X-ray analysis). Therefore, according to the present invention, there is no need for large amounts of hydrogen or steam to prevent carbon deposition, the consumption rate of the reforming catalyst is greatly reduced, the number of required catalyst ports is reduced, and the size of the reactor can be reduced. It becomes possible.

Comparative Example 1 Sulfur-containing naphtha with an ffi of 100 ppm was first heated in the presence of a Ni-Mo hydrodesulfurization catalyst at a temperature of 380°C and a pressure of 10 kg/c, LH8V, according to a conventional method.
2. Hydrogen/naphtha = 0. After hydrogenolysis under the conditions of 1 (molar ratio), it is brought into contact with a ZnO-based adsorption desulfurization agent, and -
Next, adsorption desulfurization was performed. The sulfur concentration in the obtained primary desulfurized naphtha was about 2 ppm.

The thus obtained primary desulfurized naphtha was treated in the same manner as in Example 1,
It was subjected to steam reforming.

The results are shown in FIG. In FIG. 5, curve B-1 shows the temperature profile of the catalyst layer in the reactor immediately after the start of the reaction, and curve B-2 shows the temperature profile of the catalyst layer in the reactor 200 hours after the start of the reaction.

As is clear from curve B-1, immediately after the start of the reaction, the reforming catalyst is sufficiently active, so an endothermic reaction of naphtha decomposition occurs at the inlet of the catalyst bed, the temperature decreases, and then The subsequent exothermic methanation reaction, CO
The temperature is rising due to denaturation reactions, etc.

On the other hand, as is clear from curve B-2, after 200 hours, the reforming catalyst is almost completely deactivated, and no temperature change in the catalyst layer due to endothermic or exothermic reactions is observed. Next, the desulfurized naphtha comes out of the reforming reactor unreacted.

Such a deactivated state of the reforming catalyst is determined by the amount of carbon deposited at each position on the catalyst (% of the catalyst weight) after 200 hours.
) and curve B-4 showing the amount of sulfur deposited (in % of the catalyst weight).

Such a large amount of carbon deposits not only blocks the pores of the catalyst and causes a decrease in catalyst activity, but also causes powdering of the catalyst, which in turn causes blockage of the reactor and an increase in differential pressure. Therefore,
These are matters that should be prevented as much as possible in order to operate for a long time, and they are generally prevented by using a large amount of steam or hydrogen.

Example 2 A steam reforming catalyst similar to that used in Example 1 was used for steam reforming in the same manner as in Example 1, with or without prior sulfur poisoning. Details of each catalyst are as follows.

Catalyst I: Catalyst without sulfur poisoning ■: Sulfur deposition amount: 0.05% by weight Catalyst ■: Sulfur deposition amount: 0.2% by weight The results are shown in FIG. When using catalyst I, 30
Even after 0 hours had elapsed, almost no carbon precipitation was observed, whereas in the case of catalysts (1) and (2), a large amount of carbon was deposited. This reveals that the attachment of small amounts of sulfur to the catalyst promotes carbon deposition. Therefore, the present invention, which performs steam reforming after high-level desulfurization of hydrocarbons, effectively prevents carbon deposition on the catalyst, thereby greatly contributing to extending the life of the reforming catalyst. .

Example 3 Example 1 except that naphtha subjected to high-order desulfurization and adsorption in the same manner as Example 1 was used as a raw material, and the S/C was variously changed.
Steam reforming was carried out in the same manner as above. The relationship between the amount of carbon deposited on the Ru-based catalyst at the inlet of the reactor and S/C is shown as curve C in FIG.

As is clear from Figure 7, when naphtha that has undergone high-level desulfurization is used as a raw material, carbon deposition on the catalyst does not substantially occur even if the S/C is reduced to about 0.7. .

On the other hand, when steam reforming is performed under the same conditions using the primary desulfurized naphtha obtained in the same manner as in Comparative Example 1, in order to achieve the same carbon precipitation prevention effect as above, S /C was required to be 1.5 or more, and in order to operate stably for a long period of time, S/C was required to be 2.5 or more.

Example 4 Steam reforming of purified naphtha was carried out in the same manner as in Example 3, except that a Ni-based catalyst (manufactured by coprecipitation method, NLO concentration 50% by weight), which is the most common catalyst for steam reforming, was used. I did it. The relationship between the amount of carbon deposited on the Ni-based catalyst at the inlet of the reactor and S/C is shown as a curve in FIG.

The value of S/C=1.5 required to stably suppress carbon deposition is higher than when using a highly active Ru-based catalyst. However, compared to S/C=2 or more (at the beginning of operation) required when using the primary adsorption desulfurization naphtha obtained in the same manner as Comparative Example 1 as a raw material, it is considerably lower and stable for a longer period of time. S/ necessary for driving
This is considerably lower than C=3.5 or higher.

Example 5 High-order desulfurized purified naphtha obtained in the same manner as in Example 1 and primary desulfurized purified naphtha obtained in the same manner as in Comparative Example 1 were used as raw materials, and the same Ru-based catalyst as in Example 1 was used as raw materials. Using a packed externally heated reactor (tube diameter 1.5 inch),
High-temperature steam reforming of naphtha was carried out under the conditions shown in the table.

When primary desulfurized naphtha containing 2 ppm of sulfur is used as a raw material, the activity of the catalyst is lost after 200 hours, and almost all 9 naphthas come out of the reactor unreacted. First, a pressure difference began to occur within the catalyst layer. In addition, a large amount of carbon (more than 20% by weight or more) was observed to be deposited on the catalyst near the reactor inlet.

On the other hand, when high-level desulfurization refined naphtha is used as raw material, 40
Even after 0 hours had elapsed, no activity deterioration phenomena such as naphtha slip were observed, and no carbon deposition on the catalyst was observed.

Table 2 Reaction temperature Inlet = 400℃ Outlet: 700℃ Reaction pressure 8 kg/cJ a GS/C2,
O H2/naphtha 0.1 (mole ratio) LH8V 1.2 Catalyst amount 100 cc Example 6 High temperature steam reforming of naphtha was carried out in the same manner as in Example 5 under the conditions shown in Table 3.

When highly desulfurized refined naphtha was used as a raw material, no activity deterioration phenomena such as naphtha slip were observed even after 2000 hours, and no carbon deposition on the catalyst was observed.

On the other hand, Comparative Example 1 except that LH8V during hydrodesulfurization was set to 1.
Primary desulfurized purified naphtha (sulfur-containing f) desulfurized in the same manner as
io, lppm) as the raw material, the differential pressure at the catalyst layer increased after 2000 hours, making operation impossible. At this time, a large amount of unreacted naphtha came out of the reactor. Further, when the catalyst thus used was analyzed, 10 to 20% by weight of carbon was observed to be deposited.

Table 3 Reaction temperature Population: 400°C Output temperature: 745°C Reaction pressure 8 kg/c♂・GS/C2,
O H2/naphtha 0.1 (molar ratio) LH3V 2. 0 Catalyst amount 100cc Example 7 High-level desulfurized purified naphtha obtained in the same manner as in Example 1 and primary desulfurized purified naphtha obtained in the same manner as in Comparative Example 1 were used as raw materials, respectively, and a flow-through pseudo-adiabatic reactor ( Diameter 20mm
), steam reforming was carried out under the conditions shown in Table 4 in the presence of the commercially available Ni catalyst used in Example 4.

Table 4 Reaction temperature Inlet: 490℃ (adiabatic) Reaction pressure
8 kg/ca-G Naphtha flow rate 160 cc/hr Catalyst amount 100 cc S/C2,5 H2/naphtha 0.1 (molar ratio) The results are shown in FIGS. 8 and 9.

In FIG. 8, curve E-1 and curve E-2 show the temperature profiles of the catalyst layer in the reactor immediately after the start of the reaction and 400 hours after the start of the reaction, respectively.

When using highly desulfurized refined naphtha, the temperature profile did not change even after 400 hours, as in Example 1, and the reforming catalyst continued to maintain sufficiently high activity. Therefore, according to the present invention, even when using a Ni catalyst, there is no need for a large amount of hydrogen or water vapor, which is conventionally used to prevent carbon deposition, and the consumption of the reforming catalyst is reduced. It is possible to downsize the reactor by reducing the amount of catalyst.

On the other hand, the results when using -order desulfurization naphtha are as shown in FIG. In FIG. 9, curve F-1 and curve F-2 are curves immediately after the start of the reaction and 400 minutes after the start of the reaction, respectively.
The temperature profile of the catalyst layer in the reactor after time is shown.

As is clear from the comparison between curve F-1 and curve F-2, 4
After 00 hours, the reforming catalyst near the reactor inlet has been deactivated, and the region of temperature change due to endothermic and exothermic reactions has moved toward the outlet of the catalyst layer. Also, at this time, 1
A large amount of carbon (more than 0% by weight) had been precipitated, and due to the increase in differential pressure, it was impossible to continue the operation any further.

Example 8 An external heating reactor (pipe diameter: 1.5 inch), high-temperature steam reforming of naphtha was carried out under the conditions shown in Table 5.

As a result, no activity deterioration phenomena such as naphtha slip occurred even after 600 hours, and no carbon deposition on the catalyst was observed.

Table 5 Reaction temperature Inlet: 490°C Outlet: 750°C Reaction pressure 8kg/cj-G S/C2,5 H2/naphtha 0.1 (mole ratio) LH8V 1.0 Catalyst amount 300cc Example 9 Sulfur-containing ffi 200 ppm of coke oven gas was first heated at a temperature of 380°C and a pressure of 8 kg/cJ-G in the presence of a Ni-Mo hydrodesulfurization catalyst according to a conventional method.

After hydrogenolysis under the conditions of GH8V100, it was brought into contact with a ZnO-based adsorption desulfurization agent to carry out second adsorption desulfurization. The concentration of sulfur compounds in the obtained primary adsorption desulfurization coke oven gas was approximately 0.
．． It was lppm.

On the other hand, sodium carbonate is added as an alkaline substance to a mixed aqueous solution in which copper nitrate and zinc nitrate are dissolved, and the resulting precipitate is washed and filtered, and then formed into tablets with a size of 1/8 inch in height x 1/8 inch in diameter. and fired at about 300°C. Next, the fired body (copper oxide 50%, zinc oxide 50%) 100
The primary adsorption desulfurization coke oven gas obtained above was reduced at a temperature of 200°C by passing nitrogen gas containing 2% hydrogen through a high-order desulfurization equipment (desulfurization layer length 30 cm) filled with cc.
Through Q/hr, temperature 250℃, pressure 8kg/
High-order desulfurization was carried out under ci-G conditions.

As a result, the sulfur concentration in the final purified gas is
Over 10,000 hours of operation, 0. It was less than 1 ppb.

[Brief explanation of the drawing]

1, 2, and 3 are flowcharts illustrating embodiments of the present invention. FIGS. 4 and 5 are graphs showing the influence of the degree of purification of hydrocarbons on steam reforming. FIG. 6 is a graph showing changes over time in the amount of carbon deposited during the steam reforming reaction in catalysts with different degrees of sulfur poisoning. FIG. 7 is a graph showing the relationship between S/C (number of moles of steam per mole of carbon in hydrocarbons) and the amount of carbon deposited on the catalyst in high-temperature steam reforming. FIGS. 8 and 9 are other graphs showing the influence of the degree of purification of hydrocarbons on steam reforming. (Over) Figure 4 Catalyst M ball (cm) δ 490 zu"'480 Figure 5 Catalyst N5 (cm) Figure 6 □□□-■ 100 reaction time (h") Figure 7' Fig. 8 Side opening (cm) Fig. 9 Catalyst I length (cm)

Claims (5)

[Claims] (1) The sulfur content of hydrocarbons is reduced to 5 ppb using a high-order desulfurization agent.
A method for steam reforming hydrocarbons, which comprises performing steam reforming after desulfurization. (2) The method for steam reforming hydrocarbons according to claim 1, wherein steam reforming is performed after desulfurization to a sulfur content of 1 ppb or less. (3) The method for steam reforming hydrocarbons according to claim 2, wherein steam reforming is performed after desulfurization to reduce the sulfur content to 0.1 ppb or less. (4) Claim 1 that uses a high-order desulfurization agent obtained by hydrogen reduction of a copper oxide-zinc oxide-aluminum oxide mixture prepared by a coprecipitation method using a copper compound, a zinc compound, and an aluminum compound as raw materials. The method for steam reforming hydrocarbons according to any one of items 3 to 3. (5) Any one of claims 1 to 3 which uses a high-order desulfurization agent obtained by hydrogen reduction of a copper oxide-zinc oxide mixture prepared by a coprecipitation method using a copper compound and a zinc compound as raw materials. A method for steam reforming hydrocarbons as described in .