JP4714035B2 - Method for hydrotreating wax - Google Patents

Description

  The present invention relates to a method for hydrotreating wax.

  In recent years, the regulation of sulfur content in liquid fuels such as gasoline and light oil has become stricter from the standpoint of environmental protection. For this reason, the expectation for the clean liquid fuel with low content of sulfur content and aromatic hydrocarbon is increasing. One of the methods for producing such clean fuel is a Fischer-Tropsch (FT) synthesis method using carbon monoxide and hydrogen obtained from gasification of coal or asphalt or reforming of natural gas as raw materials. . According to the FT synthesis method, it is possible to produce a liquid fuel base material that is rich in paraffin and does not contain sulfur, and wax (FT wax) can also be produced simultaneously. And FT wax is converted into middle distillates (kerosene or light oil base material) by hydrocracking.

  When middle distillate produced by wax hydrocracking or FT synthesis is used as a fuel substrate, a high yield is important from the viewpoint of economics of the process, but from the viewpoint of fuel properties, it is normal. It is desirable that the paraffin content is low and the isoparaffin content is high. For example, in light oil, when normal paraffin content increases, low-temperature fluidity | liquidity will deteriorate, and the use as goods is restricted in the worst case. Since most of the light oil produced by FT synthesis is normal paraffin, it is difficult to use it as it is.

A technique for producing a fuel base material by hydrocracking wax has been studied so far. For example, hydrocracking methods using FT wax as a raw material are described in Patent Documents 1 to 3 below. Yes.
International Publication No. 2004/028688 Pamphlet Japanese Patent Laid-Open No. 2004-255241 JP 2004-255242 A

  However, in the wax hydrocracking method described in Patent Documents 1 to 3, when the wax hydrocracking is performed for a long period of time, the catalytic activity of the catalyst deteriorates with time, and the fuel base material obtained The normal paraffin content increases, and the yield of the fuel base material decreases.

  Conventionally, the development of a high-performance wax hydrocracking catalyst has been centered, and there are no reports on improving the activity of the catalyst during operation, that is, extending the catalyst life. A typical method for producing middle distillate in the field of oil refining is hydrocracking vacuum gas oil, and low sulfur gas oil can be produced from this process. In this process, when the deterioration of the catalyst is greater than expected, it is common to take measures such as reducing the amount of raw material supply or reducing the decomposition rate in order to operate for a predetermined period. However, such treatment is not preferable because it reduces the operation efficiency. Therefore, there is a strong demand for the development of a catalyst reactivation method that can suppress catalyst deterioration, that is, cope with a case where catalyst deterioration occurs more than expected.

  The present invention has been made in view of the above-mentioned problems of the prior art, and when hydrocracking wax over a long period of time, it improves the catalytic activity that deteriorates over time, and the normal paraffin content is sufficiently reduced. Another object of the present invention is to provide a method for hydrotreating wax capable of obtaining a good fuel substrate in a good yield.

  In order to achieve the above object, the present invention uses, as a raw material, a wax containing 70% by mass or more of normal paraffins having 16 or more carbon atoms, and in the presence of hydrogen, the wax is cycled on a carrier containing an amorphous solid acid. A first step of hydrocracking by bringing it into contact with a catalyst supporting a Group VIII metal in the table, and 60 wt% or more of paraffins having 9 to 21 carbon atoms from the wax temporarily from the wax A second step of hydrocracking by bringing the light paraffin into contact with the catalyst in the presence of hydrogen in the presence of hydrogen, and switching the raw material from the light paraffin to the wax in the presence of hydrogen. And a third step of hydrocracking the wax by contacting it with the catalyst. To provide a management method.

  According to the wax hydrotreating method, when the wax is hydrocracked using a catalyst in which a group VIII metal in the periodic table is supported on a support containing an amorphous solid acid, the raw material is temporarily used. By switching to light paraffin and hydrocracking the light paraffin with the catalyst, the catalytic activity of the catalyst deteriorated with time during the hydrocracking of the previous wax can be improved. By switching to wax again, a fuel base material in which the normal paraffin content is sufficiently reduced over a long period of time can be obtained with good yield.

  In the wax hydrotreating method of the present invention, the wax is preferably one produced by Fischer-Tropsch synthesis (FT synthesis) (FT wax). By using such FT wax as a raw material, the yield of middle distillate tends to be improved.

  In the wax hydrotreating method of the present invention, the light paraffin is preferably produced by Fischer-Tropsch synthesis. By using such light paraffin, the reaction temperature in the third step tends to be sufficiently lowered.

  Furthermore, in the method for hydrotreating a wax of the present invention, the second step is preferably performed under a reaction temperature of 150 to 320 ° C. By performing the hydrogenation treatment of light paraffin at a reaction temperature of 150 to 320 ° C., the catalytic activity of the catalyst deteriorated with time can be more sufficiently improved, and the normal paraffin content is more sufficiently reduced over a long period of time. It is possible to obtain a higher fuel substrate with a higher yield.

  According to the present invention, when hydrocracking wax over a long period of time, it is possible to improve the catalytic activity of a catalyst that deteriorates with time and to obtain a fuel base material with a sufficiently reduced normal paraffin content in good yield. A wax hydroprocessing method can be provided.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  The wax hydrotreating method of the present invention uses, as a raw material, a wax containing 70% by mass or more of normal paraffins having 16 or more carbon atoms, and in the presence of hydrogen, the wax is periodically regulated on a carrier containing an amorphous solid acid. 1st process of hydrocracking by making it contact with the catalyst which carry | supports the group VIII metal in a table | surface, and the said raw material contains 60 mass% or more of paraffins of 9-21 carbon atoms from the said wax temporarily. A second step of hydrocracking by contacting the light paraffin with the catalyst in the presence of hydrogen, and switching the raw material from the light paraffin to the wax, in the presence of hydrogen. And a third step of hydrocracking the wax by contacting with the catalyst.

  The wax hydrogenation treatment in the present invention can be carried out, for example, using a fixed bed reactor filled with a catalyst. The wax as a raw material is introduced into a fixed bed reactor and hydrocracked by contacting with a catalyst in a hydrogen atmosphere to obtain a product oil.

  Here, as the hydrocracking catalyst charged in the reactor, a catalyst obtained by supporting a Group VIII metal in the periodic table on a support containing an amorphous solid acid is used. Moreover, as a support | carrier, it is preferable to use what shape | molded the amorphous solid acid into the pellet form using the binder.

  Examples of the amorphous solid acid include silica alumina, silica zirconia, alumina boria, and silica magnesia. Among these, silica alumina and alumina boria are preferably used. These can be used individually by 1 type or in combination of 2 or more types. Further, the content of the amorphous solid acid in the catalyst is preferably 20 to 100% by mass, more preferably 50 to 100% by mass based on the total amount of the catalyst.

  As the binder, for example, silica, alumina or the like can be used, and alumina is preferably used. The content of the binder in the catalyst is preferably 0 to 80% by mass, more preferably 0 to 50% by mass based on the total amount of the catalyst.

  In addition, examples of the Group VIII metal in the periodic table supported on the carrier include nickel, rhodium, palladium, iridium, and platinum. Of these, palladium and platinum are preferably used. These can be used individually by 1 type or in combination of 2 or more types. In particular, when using a slack wax containing oil as a raw material, it is preferable to mix palladium and platinum and carry them on a carrier. The loading amount of the Group VIII metal in the catalyst is preferably 0.01 to 2.0 mass%, more preferably 0.1 to 1.0 mass%, based on the total amount of the catalyst.

  The wax used as a raw material in the first and third steps of the wax hydrotreating method of the present invention has 16 or more carbon atoms, preferably 20 or more carbon atoms, more preferably 21 or more carbon atoms. This is a petroleum or synthetic wax containing 70% by mass or more of normal paraffin. Examples of the petroleum wax include slack wax and micro wax, and examples of the synthetic wax include so-called FT wax produced by FT synthesis. Among these, it is preferable to use FT wax.

  The light paraffin used as a raw material in the second step of the wax hydrotreating method of the present invention is a fuel base material containing 60% by mass or more of paraffin having 9 to 21 carbon atoms, and having 9 to 20 carbon atoms. It is preferably a fuel substrate containing 60% by mass or more of paraffin, more preferably a fuel substrate containing 70% by mass or more of paraffin having 9 to 20 carbon atoms, and FT synthesis production having 9 to 20 carbon atoms. More preferably, it is an oil.

  As reaction conditions in the first and third steps, the reaction temperature is usually preferably 270 to 360 ° C, more preferably 300 to 350 ° C. When the reaction temperature is less than 270 ° C., the normal paraffin content of the produced middle distillate tends to increase, and when it exceeds 360 ° C., the yield of the middle distillate tends to decrease. In particular, when the reaction temperature exceeds 370 ° C., an aromatic compound is easily generated as compared with the case where the reaction temperature is within the above range, which is not preferable from the viewpoint of obtaining a clean fuel substrate.

In the first and third steps, the liquid hourly space velocity (LHSV) of the wax with respect to the catalyst in the fixed bed reactor is preferably 0.1 to 5.0 h ^−1, and is preferably 0.3 to 3. More preferably, it is 0h- ¹ . Tendency to liquid hourly space velocity is less than 0.1 h ^-1, is in the resulting tendency of normal paraffin content of the middle distillate is high, exceeding 5.0 h ^-1, the yield of middle distillate lowered It is in.

  Furthermore, in the first and third steps, the pressure during the reaction affects the decomposition activity, so that it is preferably 1.0 to 10.0 MPa, more preferably 2.0 to 7.0 MPa. . If the pressure is less than 1.0 MPa, the catalyst tends to deteriorate, and if it exceeds 10.0 MPa, the yield of middle distillate tends to decrease.

  In the first and third steps, the hydrogen oil ratio is not particularly limited, but it is usually preferably 50 NL / L or more. When the hydrogen oil ratio is less than 50 NL / L, olefins are easily contained in the produced middle distillate, and the oxidation stability as a fuel tends to be lowered.

  Moreover, as reaction conditions in a 2nd process, it is preferable that reaction temperature shall be 150-320 degreeC, and it is more preferable to set it as 180-310 degreeC. If the reaction temperature is less than 150 ° C., isomerization of light paraffin hardly occurs, the catalytic activity is not sufficiently improved, and the normal paraffin content of the fuel substrate obtained in the third step tends to increase. When it exceeds 320 ° C., the light paraffin as a raw material is lightened, and the yield of the finally obtained fuel base material tends to decrease.

In the second step, the liquid hourly space velocity of light paraffins to catalyst in the fixed bed reactor (LHSV) is preferably set to 0.1 h ^-1 or more, more it is 0.5h ^-1 or preferable. When the liquid space velocity is less than 0.1 h ⁻¹ , it takes time to sufficiently improve the catalyst activity, which is not preferable.

  Furthermore, in the second step, the pressure during the reaction is not particularly limited, but it is preferably a pressure in the same range as the first step, and it is more preferable to maintain the pressure in the first step in terms of operation. preferable. Further, in the second step, the hydrogen oil ratio is not particularly limited, but is preferably set to a hydrogen oil ratio in the same range as the first step, and the hydrogen oil ratio in the first step is maintained for operation. It is more preferable.

  By performing the wax hydrogenation process through the first to third steps described above, the catalytic activity of the catalyst that deteriorates with time can be improved by performing the second step, and the normal paraffin content over a long period of time. Thus, it is possible to obtain a fuel base material with a sufficient reduction in the yield.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
FT wax (20 to 80 carbon atoms, normal paraffin content of 21 or more carbon atoms: 95 mass%) was prepared as a raw material for hydrocracking. In addition, silica alumina (alumina content: 0.16 mol%) and an alumina binder were mixed at a mass ratio of 80:20, molded into a cylindrical shape having a diameter of about 1.5 mm and a length of about 3 mm, and then at 500 ° C. The catalyst carrier was obtained by calcination for 1 hour. The obtained catalyst carrier was impregnated with a mixed aqueous solution of chloroplatinic acid and tetraamminedichloropalladium, dried at 120 ° C. for 3 hours, and then calcined at 500 ° C. for 1 hour, whereby platinum and palladium were massed on the catalyst carrier. A hydrocracking catalyst having a ratio of 90:10 and 0.8% by mass supported based on the total amount of the catalyst was produced.

Next, 200 ml of the catalyst was charged into a fixed bed reactor, and metal (platinum and palladium) was reduced under a hydrogen stream at 345 ° C. for 4 hours before the reaction. Thereafter, the decomposition rate of the raw material becomes 80% by mass under the conditions of the liquid space velocity of the raw material with respect to the catalyst of 1.5 h ⁻¹ (the liquid flow rate is 300 ml / h), the pressure of 2.8 MPa, and the hydrogen oil ratio of 570 NL / L. In this way, the raw material was subjected to hydrogenation treatment continuously for 30 days while always adjusting the reaction temperature (first step). The product oil obtained during this time was distilled together to obtain light paraffin A having 10 to 20 carbon atoms (paraffin content: 99% by mass).

Thirty days after the start of the hydrogenation operation, the raw material was switched from FT wax to light paraffin A, and light paraffin A was subjected to hydrogenation treatment for 24 hours (second step). The reaction conditions in this treatment were a reaction temperature of 310 ° C., a liquid space velocity of 2.5 h ⁻¹ , a pressure of 2.8 MPa, and a hydrogen oil ratio of 350 NL / L.

  After the hydrogenation treatment of light paraffin A, the raw material was returned to the FT wax again, and the hydrogenation treatment was performed under the initial conditions (similar decomposition rate of 80% by mass as in the first step) (third step). .

  As the reaction temperature in the above-mentioned series of hydroprocessing, the temperature at the start of the reaction (reaction start temperature), the temperature immediately before switching the raw material from FT wax to light paraffin A (temperature before light oil treatment), and the raw material from light paraffin Table 1 shows the temperature immediately after switching to the FT wax (temperature after light oil treatment). This reaction temperature is an indicator of the catalyst activity, and the lower the reaction temperature, the better the catalyst activity. In addition, among the product oils obtained by hydroprocessing after switching the raw material from light paraffin to FT wax again, the normal paraffin content (index of isomerization) of the product oil having a boiling point of 145 to 360 ° C. and its yield Is shown in Table 1.

(Example 2)
As a raw material in the second step, instead of the light paraffin A, a middle distillate having 9 to 22 carbon atoms produced by FT synthesis (paraffin content having 9 to 20 carbon atoms: 89% by mass) was used. The hydrogenation process of the said 1st-3rd process was performed like Example 1. FIG. Table 1 shows the reaction temperature, the normal paraffin content (index of isomerization) of the product oil having a boiling point of 145 to 360 ° C., and the yield thereof in the series of hydroprocessing.

(Example 3)
The hydrogenation process of the said 1st-3rd process was performed like Example 1 except having made reaction temperature in the hydrogenation process of the light paraffin A in a 2nd process into 335 degreeC. Table 1 shows the reaction temperature, the normal paraffin content (index of isomerization) of the product oil having a boiling point of 145 to 360 ° C., and the yield thereof in the series of hydroprocessing.

Example 4
The hydrogenation process of the said 1st-3rd process was performed like Example 1 except having made the reaction temperature in the hydrogenation process of the light paraffin A in a 2nd process into 120 degreeC. Table 1 shows the reaction temperature, the normal paraffin content (index of isomerization) of the product oil having a boiling point of 145 to 360 ° C., and the yield thereof in the series of hydroprocessing.

(Comparative Example 1)
The FT wax was hydrogenated in the same manner as in Example 1 except that the first step was continuously performed without performing the second step. Table 1 shows the reaction temperature 30 days after the start of the FT wax hydrogenation operation as “temperature before light oil treatment” and the reaction temperature after 24 hours as “temperature after light oil treatment”. Table 1 shows the normal paraffin content (an index of isomerization) and the yield of the product oil having a boiling point of 145 to 360 ° C. obtained after 31 days from the start of operation.

  As is apparent from the results shown in Table 1, when hydrocracking wax for a long period of time, the activity of the catalyst deteriorated with time is improved by supplying light paraffin temporarily during the hydrocracking operation. It was confirmed that a fuel base material rich in isoparaffin (low in normal paraffin) can be obtained with good yield.

Claims (4)

A wax containing 70% by mass or more of normal paraffins having 16 or more carbon atoms is used as a raw material, and in the presence of hydrogen, the wax is supported on a carrier containing an amorphous solid acid with a Group VIII metal in the periodic table. A first step of hydrocracking by contacting with a catalyst comprising:
The raw material is temporarily changed from the wax to a light paraffin containing 9 to 21 mass% of paraffins having 9 to 21 carbon atoms, and hydrocracked by bringing the light paraffin into contact with the catalyst in the presence of hydrogen. Two steps;
A third step of switching the raw material from the light paraffin to the wax and hydrocracking the wax in contact with the catalyst in the presence of hydrogen;
A method for hydrotreating a wax, comprising:   2. The wax hydrotreating method according to claim 1, wherein the wax is produced by Fischer-Tropsch synthesis.   3. The wax hydrotreating method according to claim 1, wherein the light paraffin is produced by Fischer-Tropsch synthesis.   The wax hydrotreating method according to any one of claims 1 to 3, wherein the second step is performed under a reaction temperature of 150 to 320 ° C.