JPH01188406A - Production of hydrogen from kerosene fraction - Google Patents

Abstract

PURPOSE:To produce hydrogen stably for a long time and economically by carrying out reforming of kerosene in the presence of a steam reforming catalyst after removing S from the feed kerosene and adding water thereto. CONSTITUTION:Kerosene contg. <=0.2ppm by wt. S is obtd. from a kerosene fraction A having <=150ppm. by wt. S content mixed with gaseous H2 after pressurizing to a reaction pressure with a pump B, by feeding the mixture to a hydrodesulfurization reactor D after heating through a heat exchanger C, where the mixture is allowed to contact with a hydro refining catalyst E and an H2S absorbing agent F under <=50kg/cm<2>.G at 270-400 deg.C, 0.5-7 LHSV, 0.02-1.0Nm<3> H2/kg kerosene, then passing the product through a desulfurizing tower H after adjusting the temp. to 180-300 deg.C through a heat exchanger G. After mixing the obtd. kerosene with water L supplied from a pump M, the obtd. mixture is fed to a reformer I, where it is allowed to contact with an Ni adsorber at 150-350 deg.C under <=50kg/cm<2>.G and 0.1-10 LHSV. Then, the product is introduced into a reactor J through a heat exchanger C, and allowed to contact with a steam reforming catalyst to reduce the content of CO, and separated from condensate in a knockout drum K.

Description

[Detailed description of the invention] Industrial field of application The present invention removes sulfur contained in kerosene using a hydrodesulfurization catalyst, a hydrogen sulfide adsorbent, and a Ni-based sorbent, and then adds water to the kerosene. This invention relates to a method for producing hydrogen by carrying out a reforming reaction using a steam reforming catalyst-1-.

Problems to be solved by conventional technology and invention Hydrogen has many uses such as raw material, refining, and fuel, including water electrolysis, steam reforming of hydrocarbons or alcohol, partial oxidation, decomposition, and dehydration. It is manufactured using methods such as Hydrogen obtained by electrolysis of water is expensive, but because it is highly pure, it is used for special purposes such as physical and chemical experiments. When hydrogen is used industrially as a raw material or for purification, hydrogen is often produced by steam reforming or partial oxidation of inexpensive and easily available raw materials.
Among these, hydrogen is mostly produced from light hydrocarbons or alcohols by steam reforming, with the exception of a few cases in which hydrogen is produced by partial oxidation from coal or heavy residual oil. As a light hydrocarbon or alcohol,
Methane, ethane, propene, and butane alone or in mixtures, or gases containing them, light naphtha, heavy naphtha, and methanol have been used industrially.

Kerosene fractions are easy to handle due to their boiling point, flash point, and other properties, have few problems in storage and distribution, and are inexpensive raw materials, but they have no proven track record as raw materials for hydrogen production. The biggest reason for this is that it is not possible to economically remove the sulfur content in the kerosene fraction to a concentration below that which the reforming catalyst, which is sensitive to sulfur compounds, can tolerate (sulfur content of 0.2 ppm or less). This is because of this.

Therefore, the present inventors brought a kerosene fraction with a sulfur content of 150 ppm or less into contact with a hydrodesulfurization catalyst, a hydrogen sulfide adsorbent, and an Nl-based sorbent to reduce the sulfur content to a level that can be tolerated by the reforming catalyst. The present invention was developed as a result of extensive research into a method for producing hydrogen by steam reforming the hydrogen.

Conventionally, as a method for removing sulfur compounds from Ishiura compounds, the hydrodesulfurization method is known, in which treatment is carried out at high temperature and pressure using a catalyst such as cobalt-molybdenum, nickel-molybdenum, or nickel-tungsten in the presence of hydrogen-containing gas. It is being However, in order to keep the sulfur content in the kerosene fraction below 0.2 ppm for a long time using this method,
It was found that this method is not an economical desulfurization method because it requires a high pressure of 00 kg/cm2.6 or more and an LHSV of 0.1 h-' or less.

Next, it is known that sulfur compounds such as zinc oxide, copper oxide, manganese oxide, and iron oxide are adsorbed, and these metal oxides alone can adsorb and remove the sulfur content in the kerosene fraction to 0.2 ppa+ or less. We have confirmed through experiments that this is completely impossible.

Next, although it is known that Ni-based sorbents adsorb and remove trace amounts of sulfur in naphtha fractions during the naphtha forming process, there is no example of this being applied to kerosene fractions, and the present inventors In Japanese Patent Application No. 61-175322, it was revealed that the sulfur content in kerosene fractions could be adsorbed and removed under limited conditions. However, over a long period of time, the sulfur content in kerosene was reduced to 0. It has been found that reducing the content to 2 ppm or less requires a large amount of Ni-based sorbent, which is not necessarily economical.

Therefore, the present inventors removed the sulfur content in the kerosene fraction to a predetermined amount or less by combining a hydrodesulfurization catalyst, a hydrogen sulfide adsorbent, and a Ni-based sorbent, thereby economically producing hydrogen from kerosene. As a result of studies on methods to do this, the present invention was arrived at.

Means for Solving the Problems The kerosene fraction used as a raw material in the present invention has a sulfur content of 150
ppa+, flash point 40℃ or higher, 95% distillation temperature 270℃
Those having the following properties are desirable and easily available as commercial products.

In the present invention, this kerosene is first brought into contact with a hydrodesulfurization catalyst.

The desulfurization catalyst preferably contains cobalt-molybdenum, nickel-molybdenum, nickel-cobalt-molybdenum, and nickel-tungsten as active metals, and is supported on alumina or an oxide support mainly composed of alumina. Cobalt and/or nickel is preferably supported in an amount of 2 to 7 vt% as an oxide, and molybdenum or tungsten is preferably supported in an amount of 8 to 25 vt% as an oxide.

As for the shape, the diameter is 0.7~51111% and the length is 10mm.
You can choose from the following extrusion molded products or tablet products. The diametrical cross section may be circular, trefoil, quatrefoil, etc. A predetermined amount of this desulfurization catalyst is charged into a desulfurization reactor, and reduction with hydrogen gas and preliminary sulfurization with a sulfurizing agent are performed in advance. The reduction and presulfurization may be carried out in advance in separate containers and then charged into the desulfurization reactor. Once the catalyst has been pretreated, kerosene and hydrogen-containing gas can be introduced into the reactor under predetermined conditions.

Although the hydrogen-containing gas can be supplied externally, it is convenient to recycle a portion of the hydrogen produced according to the invention. The reformed gas leaving the steam reformer is usually in thermodynamic equilibrium with H2, C02, C01H201CH4,
It consists of a trace amount of Ca, and components other than hydrogen are removed or left as is, depending on the use of hydrogen. Therefore, the hydrogen-containing gas to be recycled only needs to contain substantially 30% or more of hydrogen.

Kerosene and hydrogen-containing gas pass through the desulfurization reactor either downward or upward, but the reaction pressure is below 50 kg/cm2・G.
In particular, when hydrogen is simply produced without being subject to the High Pressure Gas Control Law, a pressure of less than 10 kg/cm2·G is desirable. The reaction temperature may be in the range of 250 to 400°C, and the LHSV may be in the range of 0.2 to 7 h-1. The hydrogen/kerosene ratio is preferably within the range of 0802 to 1.0 Nm3/kg kerosene as pure hydrogen.

Next, hydrogen sulfide generated by the desulfurization reaction must be removed with a hydrogen sulfide absorbent. As a hydrogen sulfide absorbent, caustic softa showing basicity, caustic potash, magnesium hydroxide, calcium hydroxide, monoethanolamine, jetanolamine, isopropylamine, ZnoSCub%F
e205-Cr20! , Zn0-Cu
bs Zn0-M 6 0 l s Z
There are n0-F, l:203, etc., but when the sulfur content in the kerosene is 150 ppm or less as in the present invention, a solid absorbent such as ZnO is preferable from the viewpoint of convenience and economy.

The hydrogen sulfide absorbent may be filled in a separate container from the desulfurization catalyst, or may be filled in the same container immediately after the desulfurization catalyst. If packed in a separate container, the reaction conditions should be the same as the desulfurization conditions.

The kerosene that has passed through the hydrogen sulfide absorbent is brought into contact with the Ni-based sorbent, but it is important to change the method of contact depending on the concentration of CO2 and CO contained in the hydrogen-containing gas. That is, when the total of CO2 and CO is 2VOW% or less, kerosene and hydrogen-containing gas are directly brought into contact with the Ni-based sorbent. C
The sum of O2 and CO is 2 v0. f: If it exceeds %, cool the kerosene and hydrogen-containing gas as necessary to separate the gas and liquid.
After only liquid phase kerosene is brought into contact with the Ni-based sorbent in an upward or downward direction, the hydrogen-containing kerosene is combined with the gas. This is C
This is because o reacts with H2 on the Ni-based sorbent, producing methane with heat generation, and if it exceeds 2 vo:%, the temperature will rise, which is dangerous. Similar consideration is required since CO2 becomes CO on the desulfurization catalyst or the Ni-based sorbent.

The Ni-based sorbent used in the present invention contains 40 to 70 νt% of Ni.
It can be used even if it contains small amounts of copper, chromium, zirconium, magnesium and other metal components. As the carrier, silica, alumina, silica-alumina, titania, zirconia, zinc oxide, clay, clays, diatomaceous earth and other refractory inorganic oxides can be used. The shape of the sorbent may be a tablet molded product, an extrusion molded product, or a spherical product, and the size is 0.7
~5 pieces is good. In order to avoid the risk of ignition, these sorbents may or may not have their surfaces stabilized by oxidizing a portion of the metal nickel or adsorbing carbon dioxide gas. 150-400℃ prior to use
Hydrogen reduction may be carried out within the range of 100 to 100%, or adsorbed carbon dioxide gas may be removed with an inert gas.

For kerosene, whether accompanied by hydrogen-containing gas or not, the pressure is 50 kg/c or less, the temperature is 150 to 350 degrees Celsius, and the LH
It is brought into contact with a Ni-based sorbent under conditions of SV0.1 to 10h-' (7).

The sulfur content of the kerosene treated in such a manner and under such conditions is reduced to 0.2 wtpps or less, and is fully suitable as a raw material for the next stage of steam reforming.

The kerosene obtained by the method of the present invention is mixed with hydrogen-containing gas and steam necessary for steam reforming, and then sent to a steam reformer and brought into contact with a reforming catalyst. The reforming catalyst contains 5 to 50w1% of nickel as an active metal, preferably 10 to 50w1%.
It is preferable that the content is 35vt%, and it may also contain ruthenium or the like.

As the carrier, alumina is preferred, but magnesia, silica, calcia, and magnesia-alumina spinel may be used alone or in combination. Also used is a catalyst containing 10% or less of an oxide of an alkali metal, alkaline earth metal, or rare earth metal as a cocatalyst for the purpose of preventing carbon precipitation.

In reforming hydrocarbons with a large number of carbon atoms such as kerosene, it is preferable to fill the first catalyst layer with a catalyst containing a co-catalyst and fill the second catalyst layer with a catalyst that does not contain a co-catalyst. The reaction temperature is 400-600°C at the catalyst bed inlet, 600-900°C at the outlet,
Pressure is 1 to 30 kg/cJ, G1 steam/carbon molar ratio 3.5 to 6.5, hydrogen/kerosene 0.05 to 0.7 Nm'
It is preferable to reform kerosene under the conditions of /kg%LHSVO12-4.

In addition to hydrogen, which is the main component, the reformed gas also contains CO2, C
It contains 05CH4 and H20, and it is best to combine purification steps depending on the use of hydrogen.

When removing CO, the gas is reformed in series with a high-temperature shift catalyst such as Fe2O3Cr203 at 300 to 500°C and with a low-temperature shift catalyst such as CuO-ZnO at 150 to 2.50°C. contact to reduce CO to a predetermined amount or less.

In order to reduce CO to 1 voi% or less, treatment is further carried out using a methanator filled with a Ni catalyst.

If it is necessary to remove CO2 in addition to CO, it is preferable to purify using a basic substance such as KOH. The purified hydrogen-containing gas is used for each purpose, but it is preferable that a portion of it be recycled to the inlet of the hydrodesulfurization tower.

Next, an example of a process flow diagram in which the present invention is effectively implemented will be shown and explained.

First, in Figure 1, the total concentration of CO2 and CO contained in the hydrogen-containing gas used for hydrorefining is 2V.

This is an example of less than ヱ%. First, commercially available No. 1 kerosene is put into the raw material tank (A), and the pressure is increased to the reaction pressure using the pump (B). The accompanying hydrogen-containing gas is mixed therein, and the gas-liquid mixture is transferred to the heat exchanger (C ) and is heated by heat exchange with the reformed reaction product to the temperature required for the reaction. Next, it enters the hydrodesulfurization reactor (D), and first the pressure is 50 kg/c.
m2・G or less, temperature 250-400℃, LHSV0.5
717), most of the sulfur compounds in the kerosene are hydrocracked while passing through the hydrorefining catalyst (E) and converted into light compounds mainly composed of hydrogen sulfide. Most of these sulfur compounds are adsorbed and removed while passing through a zinc oxide desulfurization layer (F) packed downstream of the hydrorefining catalyst in the same reactor. The kerosene and hydrogen-containing gas that have passed through the zinc oxide layer (F) and exited the reaction tube are brought into contact with a nickel-containing catalyst in a desulfurization tower (H) whose temperature is controlled at 180 to 300°C by a heat exchanger (G), where they remain. The sulfur compounds are collected and removed to reduce the sulfur content to 0.2 wt.
Kerosene with a sulfur content of 0.2 vtppm thus obtained
After adding the required amount of water (steam) from the water tank (L) through the pump (M), the following kerosene enters the reforming reactor (I), where it comes into contact with a steam reforming catalyst, is decomposed and gasified. Ru. This reformed gas is cooled in a heat exchanger (C) and then passes through a reactor (J) filled with a shift reaction catalyst.
- After reducing the carbon oxide content and increasing the hydrogen content, it is cooled and the condensate is separated in a knockout drum (K).

Next, Figure 2 shows the CO2 and CO contained in the hydrogen-containing gas.
FIG. 2 is a schematic diagram of a process flow when the total concentration exceeds 2 vof%. First, commercially available No. 1 kerosene is put into the raw material tank (A), and the pressure is increased to the reaction pressure using the pump (B). The accompanying hydrogen-containing gas is mixed therein, and the gas-liquid mixture is transferred to the heat exchanger (C ) and is heated by heat exchange with the reforming reaction product to the temperature required for the reaction. Next, it enters the hydrodesulfurization reactor (D), and first, the pressure is 50 kg/C sea G or less, the temperature is 250 to 400 degrees Celsius, and the LHSVO is 15 to 7.
Most of the sulfur compounds in No. 1 kerosene are hydrocracked while passing through the hydrorefining catalyst (E) in the range of 100 to 1000 ml, and are converted into light compounds mainly composed of hydrogen sulfide.

These sulfur compounds are adsorbed and removed while passing through a zinc oxide desulfurization layer (F) packed downstream of the hydrotreating catalyst in the same reactor. The kerosene that has passed through the zinc oxide layer (F) and exited the reaction tube is cooled in a gas-liquid separator (N), separated into hydrogen-containing gas and kerosene, and then further separated into 180% gas and kerosene in a heat exchanger (G).
Only the liquid phase fraction heated to ~300℃ is sent to the desulfurization tower (H)
The remaining sulfur compounds are sorbed and removed by contacting with a nickel-containing catalyst to obtain kerosene with a sulfur content of 0.2 ppI11 or less.

The thus obtained kerosene with a sulfur content of 0.2 ppm or less is combined with the hydrogen-containing gas that was previously separated in (N), and then passed from the water tank (L) to the pump (M) to produce the required amount of water (steam). ) is added to the reforming reactor (1), where it comes into contact with a steam reforming catalyst to be decomposed and gasified. After this reformed gas is cooled in a heat exchanger (C), it passes through a reactor (J) filled with a shift reaction catalyst to reduce the carbon oxide content and increase the hydrogen content. It is cooled and the condensate is separated in a knockout drum (K).

EXAMPLES Next, the method of the present invention will be specifically explained using examples.

Example 1 First, the following processing was performed according to the flow shown in FIG. Commercially available No. 1 kerosene [sulfur content 26 vtpp-1 specific gravity 0.796 (15/4°C), boiling point range 164-262
℃, aromatic content 17.0 voj! %, smoke point 28 mm] as raw material, commercially available cobalt (2.5vt as CoO
%) - Molybdenum (12,5vt% as Moat) alumina hydrodesulfurization catalyst 40- and immediately afterwards Zn040m as hydrogen sulfide absorbent! The reaction pressure is 10 kg/cm2 by the hydrorefining equipment in which 2 is filled in the same container.
-G, temperature 380℃, LH8V5, hydrogen/oil conversion 0.5N
mlH2/kg (H295vo name% or more, CO2+C0
, 2vo name%.

The hydrogenation treatment was carried out under the following conditions. Approximately 2-3p for processed oil
Sulfur of pIIl remained. This refined oil is heated to 280℃
The reaction pressure was 9 kg/cd-G, the temperature was 200°C, and the LHS was cooled to 200°C.
It was treated under the conditions of VI. A stainless steel tube with an inner diameter of 20 mm was used as the sorption tower, and the tube was filled with 200 mm of sorbent. The sulfur content of refined oil is 0, 2 vtppffl
It decreased to below.

Next, this refined oil was introduced into a reforming tower with an inner diameter of 15 mm, and N
34 wt% iO, 12 wt% Atz Oi, Mg
Using a steam reforming catalyst consisting of 54 wt% O, the reaction pressure was 9 kg/c-G, and the temperature at the reaction tube inlet was 500°C.
, outlet 850℃, hydrogen/kerosene - 0.5NmiH2/kg
The treatment was carried out under the conditions of SLH8V1.5, H20/C, 3.5 mol and 1 mol. Even after 5,000 hours had passed since the start of the reaction, there was almost no change in the temperature distribution in the reaction tube, and the outlet gas composition was close to the thermodynamic equilibrium value, with the sulfur content being 0,
It has become clear that even kerosene can be sufficiently reformed by steam to produce hydrogen if it is reduced to 2 vtpp11 or less.

Example 2 Commercially available No. 1 kerosene (sulfur content: 38 wtppa+) was used as a raw material and treated using an apparatus having the process flow shown in FIG. First, raw kerosene is introduced into a reaction tower filled with a nickel-molybdenum catalyst and a hydrogen sulfide absorbent ZnO in the same container, and the reaction pressure is 9. kg/c-・G1 temperature 3
00℃, LHSV0.5, hydrogen/oil conversion 0.06Nm3
H2/kg (H2,74vo℃%, CO+CO2,2
5.3vo1%).

After cooling the product and separating the gas and liquid, the liquefied hydrotreated oil with a sulfur content of about 3 to 6 ppm was added to the nickel content of Example 1 with a sulfur content of 6 ppm.
It was introduced into a sulfur sorption tower filled with 5 νt% of nickel-diatomaceous earth catalyst as a sulfur sorbent, and the reaction pressure was 8.5 kg/c.
Processing was performed at m2/G1 temperature of 280°C and LHSV of 0.5.

The sulfur content of the refined oil was 0.2 νtppm or less. Next, after combining with the previously separated gas components, NiO was heated at 22v.
t%, Al2O5 26vt%, MgO 1lvt%,
CaO 13vt%, SiO 16wt% and 20%
was introduced into a reforming reaction tower filled with a steam reforming catalyst containing 7 wt%.

The reforming conditions are the same as in Example 1. 50 minutes after the start of the reaction
Even after 00 hours have passed, the maximum temperature of the reaction tube has moved slightly toward the outlet of the reaction tube, and the outlet gas composition is close to the thermodynamic equilibrium value at that temperature, with the sulfur content being 0 or 2.
It is clear that problematic hydrogen can be produced even from kerosene if it is reduced to below wtppm.

Comparative Example 1 The commercially available No. 1 kerosene used in Example 2 was used as a raw material, and the same commercially available cobalt (2.5 νt% as CoO)-molybdenum (12.5 νt% as MeO2) alumina catalyst and hydrogen sulfide absorbent ZnO were used. A reaction tower packed in a container was set at a reaction pressure of 20 kg/c, a G1 temperature of 360°C, and a LHSV of 0.
．． 5. Hydrogen/oil conversion 0.3 mol 1 mol (H2,74voi
%, CO+CO2,25,3v0. g%). The product was directly introduced into the reforming reactor, but when the product was sampled and the sulfur content of the kerosene was measured, it was found to be 0.0 from the beginning of the oil flow up to 1000 hours. 02wLppm, but after that it gradually increased to 1wLppm after 2000 hours.
ppfl1 or more, and the processing time was extremely short. The hydrotreated products were sequentially introduced into a reforming reactor, and a steam reforming reaction was carried out under the same conditions as in Example 1 using the same catalyst. As a result, hydrogen gas was obtained smoothly at the beginning of the reaction, but after about 200 hours after the reaction, the endothermic part of the reaction tube gradually moved toward the outlet of the reaction tube, and the part showing the highest temperature also moved downward. After 500 hours, unreacted hydrocarbons were detected in the outlet gas.

It is clear that when the sulfur content in the raw kerosene exceeds 0.5 wtppm, the life of the nickel-based steam reforming catalyst is significantly shortened.

Comparative Example 2 Commercially available No. 1 kerosene (sulfur content: 63 νtppm) was used as a raw material, and the same nickel-diatomaceous earth catalyst with a nickel content of 65 vt% as in Example 1 was used as a sulfur sorbent at a reaction pressure of 10 kg.
/cm2·G, temperature 270°C, and LH8V0°5. The sulfur content of the treated kerosene was 0.4 wtppa+ for 1000 hours from the beginning of the oil passage, but it gradually increased thereafter and reached 1 vtpp1 or more after 20-00 hours. Subsequently, a steam reforming reaction was carried out using the obtained kerosene as a raw material and using the same catalyst as in Example 1 under the same conditions. As a result, hydrogen gas was obtained smoothly at the beginning of the reaction, but after about 125 hours after the reaction, the endothermic part of the reaction tube gradually moved toward the outlet of the reaction tube, and the part showing the highest temperature also moved downward. After 310 hours, unreacted hydrocarbons were detected in the outlet gas.

As is clear from the Examples and Comparative Examples described above, the sulfur content is 15.
A kerosene fraction with a concentration of 0 ppm or less is treated in the presence of a hydrogen-containing gas by using a hydrorefining catalyst and a hydrogen sulfide absorbent to remove most of the sulfur compounds, and then brought into contact with a nickel-based sorbent. It is clear that the sulfur content in the gas is reduced to an amount suitable for a steam reforming reaction using a nickel-based reforming catalyst, and that by implementing this process, gas consisting mainly of hydrogen can be produced stably over a long period of time. became.

[Brief explanation of the drawing]

FIG. 1 shows that the total concentration of CO2 and CO contained in the hydrogen-containing gas used for hydrorefining is 2v0. Fig. 2 is a schematic diagram showing the process flow when f: 96 or less, and the total concentration of CO2 and CO contained in the hydrogen-containing gas is 2v.
It is a schematic diagram showing a process flow when ojl: exceeds 96.

Claims (1)

[Scope of Claims] [1] A kerosene fraction with a sulfur content of 150 ppm or less is heated in the presence of a hydrogen-containing gas at a pressure of 50 kg/cm^2 G or less and a temperature of 27
0~400℃, LHSV0.2~7h^-^1, hydrogen/
After contacting the hydrodesulfurization catalyst and the hydrogen sulfide absorbent within the range of 0.02 to 1.0 Nm^3H_2/kg kerosene, the pressure is 50 kg/cm^2 G or less and the temperature is 150 to
N under the conditions of 350℃, LHSV0.1~10h^-^1
1. A method for producing hydrogen from a kerosene fraction, which comprises contacting the fraction with an i-series sorbent, adding steam, and contacting the fraction with a steam reforming catalyst under normal steam reforming conditions.