JPH0633368B2 - Pretreatment method for petroleum fraction - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pretreatment method for petroleum fractions, and more specifically, it is a feed oil for adsorbing and separating normal paraffins using molecular sieves. It relates to a pretreatment method for an oil fraction.

[Prior Art] A method for producing normal paraffin from a petroleum fraction is carried out by repeating adsorption of normal paraffin in the petroleum fraction to a molecular sieve and then desorption thereof. Trace amounts of nitrogen compounds, oxygen compounds, olefins and other polar substances contained therein are gradually adsorbed and accumulated on the molecular sieve. As a result, the adsorption capacity of normal paraffin gradually decreases, and it becomes necessary to regenerate the molecular sieve under more severe conditions, and in the worst case, it must be replaced with a new one. However, this regeneration or replacement is extremely disadvantageous economically, and in order to avoid it,
Conventionally, a petroleum fraction such as kerosene or light oil obtained from high-quality crude oil such as Arabian light crude oil and Minas crude oil having a relatively low content of the polar compounds such as the nitrogen compounds is hydrogen pressure 95 kg.
What was hydrorefined under the severe conditions of / cm ² or more and a liquid hourly space velocity of 0.8 to 1.0 was subjected to adsorption separation.

[Problems to be Solved by the Invention] By the way, the above-mentioned high-quality crude oil is expensive and is becoming difficult to obtain. Therefore, there has been a demand for a method for producing normal paraffin from a petroleum fraction obtained from crude oil containing a relatively large amount of inexpensive polar compounds such as nitrogen compounds.

That is, the problem to be solved by the present invention is to convert normal paraffins to petroleum fractions obtained from crude oils containing a relatively large amount of inexpensive polar compounds such as nitrogen compounds without decreasing the adsorption ability of normal paraffins to molecular sieves. The point is to provide a pretreatment method for effectively removing polar substances from the petroleum fraction so that the petroleum fraction can be produced.

[Means for Solving the Problems] As a means for solving the above problems, the present invention comprises treating a hydrorefined petroleum fraction with clay and then contacting it with zeolite.

As the petroleum fraction referred to in the present invention, any boiling point range obtained by distilling crude oil under atmospheric pressure can be used without any problem. However, particularly in the case of producing normal paraffin which is a raw material of sodium alkylbenzene sulfonate which is a detergent, a kerosene fraction or a light oil fraction is preferable.

The molecular sieve is a so-called molecular sieve, and a commercially available one having a commonly used pore size of about 5Å can be used.

In the method of adsorbing and separating the normal paraffin from the petroleum fraction using the molecular sieve, first, the petroleum fraction is fed through the adsorption tower filled with the molecular sieve to adsorb the normal paraffin in the petroleum fraction. next,
When the adsorption reaches saturation, the petroleum fraction remaining in the adsorption tower is discharged and the adsorbed normal paraffin is desorbed. There are a method of adsorbing in the gas phase, a method of desorbing in the gas phase under reduced pressure, and a method of adsorbing in the liquid phase and displacement desorption in the liquid phase, but the present invention can be applied to any of these methods. .

The petroleum fraction is hydrorefined prior to the adsorptive separation on the molecular sieve. Hydrorefining is performed in the presence of a catalyst in which a metal selected from Group VI and Group VIII such as nickel, cobalt, molybdenum or the like or a metal compound thereof is supported on a porous inorganic refractory such as silica, alumina or silica-alumina. And under hydrogen pressure. In this case, according to the present invention,
Hydrorefining under mild conditions is better than hydrorefining conventionally required. That is, the hydrogen pressure is 25 to 80 kg / cm ² ,
Liquid hourly space velocity 0.1 to 5 hr ^-1 , reaction temperature 250 to 350
The conditions can be appropriately selected within the range of ° C.

This hydrorefined petroleum fraction is then treated with white clay, and as this white clay, natural white clay such as acid clay and bennatoite, or activated clay obtained by treating these with sulfuric acid is preferably used. If the white clay treatment is performed by the percolation method or the contact filtration method, it can be performed easily and efficiently. The conditions of the white clay treatment cannot be unconditionally determined depending on the properties of the hydrorefined petroleum fraction or the type of the white clay to be used, but usually the liquid hourly space velocity (LHSV) is ¹ to 10 hr ^-1 , the treatment temperature. Is appropriately selected within the range of room temperature to 250 ° C.

In this clay treatment, weakly polar substances and water are eluted from the clay. This also hinders the adsorption capacity of the molecular sieve. In order to remove this, the clay fraction treated with petroleum is then brought into contact with the zeolite. This zeolite is effective whether it is natural or synthetic. In particular, A-type zeolite having a pore diameter of 4Å or 5Å or X-type zeolite having a pore diameter of 10Å, which has an excellent adsorbing ability for the weakly polar substances and water eluted from the clay, is preferable.
The method of contacting with zeolite is preferably the percolation method or the contact filtration method, because the method is simple and efficient, as in the case of the above-mentioned clay treatment. In addition, the contact conditions cannot be unconditionally determined depending on the amount of weakly polar substances and water dissolved in the petroleum fraction, but usually the liquid hourly space velocity
(LHSV) is ¹ to 10 hr ^-1 , contact temperature is room temperature to 100 ° C.
Is appropriately selected within the range.

Zeolite can adsorb water, oxygen compounds, etc., but it is difficult to remove olefins, etc. On the other hand, in the clay treatment, elution from the clay occurs, so a combination of both, and then the clay treatment first It is necessary to perform contact treatment with zeolite.

The petroleum fraction purified as described above is supplied to the step of adsorbing and separating the normal paraffin from the molecular sieve of the above-mentioned method, and the normal paraffin is produced.

[Operation] In the present invention, the petroleum fraction obtained from relatively inferior crude oil cannot be sufficiently refined by hydrorefining and the remaining polar substances such as nitrogen and oxygen compounds are removed by a clay treatment. Weakly polar substances and water that have been eluted from the clay are removed with zeolite and refined into petroleum fractions that do not reduce the ability of the molecular sieve to adsorb normal paraffin.

[Examples] Experimental example Kerosene fraction obtained by atmospheric distillation of heavy crude oil in the Middle East (total nitrogen content 20 ppm, oxygen content 1 ppm, sulfur content 5000 ppm, bromine number "measured by the method specified in JIS K2605""2.
0) using a catalyst for hydrorefining in which 3% by weight of nickel and 10% by weight of molybdenum are loaded, and the hydrogen pressure is 50 kg / c.
Hydrorefining was carried out under the conditions of m ² , liquid hourly space velocity of 1.0 hr ⁻¹ , reaction temperature of 300 ° C., and hydrogen / oil ratio of 300 m ³ / kl. The properties of this hydrorefined oil are shown in Table 3.

Next, this hydrogenated refined oil was subjected to contact treatment using activated clay (Galeonite 308D, manufactured by Mizusawa Chemical Co., Ltd.) under the conditions shown in Table 1. Table 3 shows the properties of the treated oil at this time.
o1 to 3 are shown.

This treated oil of Experiment No. 3 has a pore size of 4Å.
Type zeolite and X-type zeolite having a pore size of 10Å were contact-treated. The conditions of this contact treatment were as shown in Table 2. The results are shown in Table 4 as Experiment Nos. 4-9.
Indicated as.

Comparative Experimental Example 1 The same kerosene fraction as used in the experimental example was loaded on a catalyst for hydrorefining in which 3 wt% of nickel and 10 wt% of molybdenum were supported, hydrogen pressure of 90 kg / cm ² , liquid hourly space velocity of 1.5 hr. ^-1 , the reaction temperature was 310 ° C., and the hydrogen / oil ratio was 400 m ³ / kl. As a result, the total nitrogen content was 0.2 ppm, the oxygen content was 0.3 ppm, the sulfur content was 0.2 ppm, and the bromine index was 120.

Regarding the kerosene fraction obtained from Arabian Light,
Hydrorefining was performed under the same catalyst and conditions as above. As a result, the total nitrogen content was 0.1 ppm, the oxygen content was 0.1 ppm, the sulfur content was 0.1 ppm, and the bromine index was 90.

As is clear from these results, the petroleum fraction obtained from inferior crude oil has a high bromine index of 90 even if it is hydrorefined under severe conditions and cannot be sufficiently refined.

Comparative Experimental Example 2 The same oil as the oil after hydrorefining obtained in the experimental example was used and contacted with the same zeolite as used in the experimental example without treating with clay. About this experiment, Experiment Nos. 10-1
As 5. The conditions are shown in Table 5, and the properties of the oil after the contact treatment are shown in Method 6.

As is clear from this result, the bromine index is high and the polar substance cannot be sufficiently removed only by the contact treatment with zeolite.

[Advantages of the Invention] The present invention is a pretreatment method in which a hydrorefined petroleum fraction is treated with clay when the normal paraffin is produced from the petroleum fraction using a molecular sieve, and then a pretreatment is performed in which it is brought into contact with zeolite. Therefore, even inexpensive nitrogen compounds and the like have a special effect that normal paraffin can be produced without lowering the adsorption ability of normal paraffin to the molecular sieve from petroleum fractions obtained from crude oil containing a relatively large amount of polar substances. Further, in the present invention, hydrorefining under mild conditions is better than hydrorefining conventionally required, and therefore, in the normal case of producing normal paraffin, an existing hydrorefining apparatus can be diverted and newly constructed. It also has the side effect of requiring little to do.

Claims (1)

[Claims] 1. A petroleum fraction characterized by treating a hydrorefined petroleum fraction with clay when adsorbing and separating normal paraffin from a petroleum fraction using a molecular sieve, and then contacting it with zeolite. Pretreatment method.