JPH01259089A - Treatment of light fraction of thermally cracked heavy oil - Google Patents

Abstract

PURPOSE:To obtain a middle cut having high added value without necessitating the treatment of exhaust gas, by adsorbing and removing impurities from the light fraction of thermally cracked heavy oil, oligomerizing the purified fraction, fractionating to obtain kerosene and light oil fraction and hydrogenating the fraction. CONSTITUTION:A light fraction of thermally cracked heavy oil is made to contact with an adsorbent selected from alumina, silica alumina and silica gel to effect the adsorption and removal of impurities consisting of nitrogen compounds and oxygen compounds from the light fraction. The olefin in the purified fraction is oligomerized with a catalyst such as amorphous silica alumina or zeolite, the effluent is fractionated to obtain kerosene and light oil fraction and said fraction is hydrogenated. The adsorbent is preferably a silica gel having a surface area of 100-800m<2>/g and an average pore diameter of 10-150Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a high value-added lamp/gas oil fraction as a raw material for the pyrolysis light fraction of heavy oil.

[The light fraction obtained by thermally decomposing heavy oil contains 20 to 50 wt% of olefins that can be used effectively.

It is conceivable that this olefin can be low-polymerized to obtain a high value-added lamp/gas oil fraction, but the light fraction from heavy oil pyrolysis contains nitrogen compounds and oxygen compounds as impurities.
The catalyst contains 50 to 11,000 ppm of sulfur compounds, and these nitrogen compounds and oxygen compounds act as catalyst poisons for catalysts for low polymerization of olefins, resulting in a rapid decrease in catalytic activity.

Hydrorefining is a generally well-known pretreatment method for removing these components, but since this hydrogenates even the solenoid in the light fraction, it This is not a preferred method for removing nitrogen compounds and oxygen compounds.

Let's do it. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for processing kerosene and gas oil fractions using the above-mentioned heavy oil pyrolysis light fractions as raw materials.

Configuration of the invention. The method for treating light fractions from heavy oil pyrolysis according to the present invention is as follows: From the pre-treatment step in which impurities consisting of nitrogen compounds and oxygen compounds contained in the fraction are adsorbed and removed, ■ the low polymerization step in which the olefins in the light fraction from which impurities have been removed are subjected to low polymerization using a catalyst, ■ the low polymerization step It is characterized by a combination of four steps: (1) a fractional distillation step in which the effluent is fractionated to obtain a kerosene/gas oil fraction; and (1) a hydrogenation step in which the fractionated kerosene/light oil fraction is hydrogenated.

Each step will be explained in detail below.

■Pretreatment process The nitrogen compounds contained in the light fraction obtained by thermally decomposing heavy oil include basic compounds such as amines and pyridines, nitriles such as benzonitrile, and alkylvirols. There are non-basic oxygen compounds such as phenols, cresols, and ethers, which are acidic or neutral.

Generally, basic nitrogen compounds, which are particularly harmful to catalysts, are adsorbed and removed by alumina or silica-alumina.

Among these, surface m 100 to 800 m”/
Silica gel with an average pore diameter of 10 to 150 is particularly preferred because it simultaneously adsorbs and removes both nitrogen compounds and oxygen compounds contained in the light fraction of heavy oil pyrolysis. The pore diameter is a value determined by mercury intrusion method and nitrogen adsorption method.

Among the above silica gels, N
az O content 0.1% by weight or less, F6203 content 0
．． 0.05% by weight or less has particularly excellent ability to simultaneously adsorb and remove nitrogen compounds and oxygen compounds.

Also adsorbed nitrogen compounds and oxygen compounds.

Since it is easily desorbed at a temperature of 100 to 600°C, it is possible to regenerate the adsorbent by increasing the temperature while flowing a regeneration gas.

As the gas used for regenerating the adsorbent, air, nitrogen, water vapor, hydrogen gas, or a mixed gas thereof is used.

When the silica gel is used as an adsorbent, it can be regenerated at a relatively low temperature or using non-oxidizing gas such as nitrogen, water vapor, or hydrogen gas, so that nitrogen compounds become NO
This has the advantage that there is no need to treat the exhaust gas in the regeneration process to prevent pollution.

On the other hand, since alumina and silica-alumina as adsorbents strongly adsorb nitrogen compounds, regeneration requires combustion removal at high temperature in an oxygen atmosphere, which tends to generate NOxft, and treatment of exhaust gas during the regeneration process. You need to be careful.

This pre-treatment process is carried out continuously by installing two adsorption towers and switching between them to perform adsorption and regeneration alternately. Operations can be carried out.

(2) Low-polymerization process The olefin in the light fraction of heavy oil thermal decomposition from which impurities such as nitrogen compounds and oxygen compounds have been removed in the above-mentioned pretreatment process is low-polymerized using a catalyst.

The catalyst used in this low polymerization step is preferably amorphous silica alumina or zeolite.

Amorphous silica alumina has an alumina content lO~sowt
%, surface area 50 to 6001112/g, average pore size 1
0 to 100λ is preferable, and the surface area is BET
Surface area measurement method and average pore diameter are values determined by mercury intrusion method and nitrogen adsorption method.

As the zeolite, zeolite X, zeolite Y, mordenite, etc. are used, but the yield of the product varies depending on the pore size.

Reaction conditions are 150-400℃, 30-100K
The range of g/cm2G is preferable, and by appropriately selecting reaction conditions within this range, the ratio of each fraction of kerosene and gas oil in the low polymer can be adjusted.

The catalyst used in the low polymerization process can be regenerated by heating it while blowing air and burning the carbon deposited on the catalyst.

This low polymerization step can be operated continuously by providing two or more polymerization groups and alternately performing polymerization and catalyst regeneration.

■Fractional distillation process The effluent from the low polymerization process is fractionated to obtain a kerosene/gas oil fraction. A known distillation apparatus may be used in this step.

■Hydrogenation process The fractionated lamp/gas oil fraction is hydrogenated to produce high quality lamp/gas oil.

For the hydrogenation reaction, a normal hydrogenation catalyst such as a Co-Mo catalyst can be used, and the reaction pressure is 20 to 100 kg/1.
About cm2G, reaction temperature 200-400℃, LH3V=
0.1~10hr-', hydrogen supply amount 80~50ON/
, i1 oil (low polymer) can be easily carried out.

Further, the unreacted olefin fraction obtained from the fractionation step may be recycled to the lower polymerization step.

The present invention will be specifically explained below using Examples.

Example 1.2 and Comparative Example 1.2 Olefin content: 30 wt%, total sulfur content: 300 wt%
ppm, a total nitrogen content of 30 wt ppm, and a total oxygen content of 900 wt ppm, using a heavy oil pyrolysis light fraction as a raw material.

With or without pretreatment as shown in Table 1, reaction temperature 260°C, reaction pressure 50Kg/cm2G, flow rate i14
Figure 1 shows the relationship between the elapsed time and olefin conversion rate when polymerization was carried out over 400 ml of polymerization catalyst at 00 m i/hr.However, the silica-alumina polymerization catalyst used in Example 1 and Comparative Example 1 was , surface [444 m2/g,
The average pore diameter was 40.

Table 1 Pre-treatment uses silica gel with a surface area of 600 m2/g and an average pore diameter of 20, and LHSV=
1br-''.

In FIG. 1, the horizontal axis represents elapsed time (hr), the vertical axis represents olefin conversion rate (%), line A represents Example 1, line B represents Example 2, and line C represents Comparative Example 1. Line D is data corresponding to Comparative Example 2.

In Example 1 (Line A) and Example 2 (Line B), in which the pyrolysis light fraction of the raw material was pretreated, the initial olefin conversion rate was high and the life was long, whereas no pretreatment was performed. In Comparative Example 1 (C line) and Comparative Example 2 (D! line), the initial olefin conversion rate was low and the service life was short.

Example 3.4 and Comparative Example 3 Olefin content: 35 wt%, total sulfur content: 280 wt
ppm, total nitrogen content 30 wt ppm, total oxygen content 50 wt ppm, heavy oil pyrolysis light distillate was used as raw material, pretreated at room temperature as shown in Table 2 (LHSV=
Silica alumina catalyst (surface 1 g 444 m 27 g, average pore 714 OA
) is used to carry out low polymerization at 260° C. and 50 kg/cm 2 G. The relationship between the elapsed time and the olefin conversion rate is shown in FIG.

Table 2 In Figure 2, the horizontal axis represents elapsed time (hr), the vertical axis represents olefin conversion rate (%), E line corresponds to Example 3, FM corresponds to Example 4, and G line corresponds to Comparative Example 3. It is data.

In Example 3 (E line) and Example 4 (F line), in which the pyrolysis light fraction of the raw material was pretreated, the initial olefin conversion rate was high and the life was long, whereas no pretreatment was performed. In Comparative Example 3 (line G), the initial olefin conversion rate was low and the service life was short.

Example 5 The raw materials used in Example 1 were heated at room temperature, LHSV = 1hr-
After pretreatment with silica gel (surface area 600 m2/g, average pore diameter 20 mm), it was brought into contact with silica alumina catalyst (surface area 444 m2/g, average pore diameter 40 mm) at 260 °C, 50 kg/cm Low polymerization was carried out at 2G.

The oil obtained from the low polymerization reaction is fractionated and the kerosene fraction is converted into N
In the presence of i-Mo catalyst, 330°C, 50Kg/c
Hydrogenation was performed at m2G, LHSV=2.0hr-''.

The results are shown in Table 3.

(Left below) Table 3 Effects of the invention Heavy oil pyrolysis light distillates can be converted into high value-added middle distillates such as kerosene and gas oil as raw materials.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing the relationship between the elapsed time of the low polymerization reaction and the olefin conversion rate in Examples and Comparative Examples.

Claims (1)

[Claims] 1(1) A light fraction of heavy oil pyrolysis is brought into contact with an adsorbent selected from the group consisting of alumina, silica alumina, and silica gel to remove nitrogen compounds and oxygen compounds contained in the light fraction. (2) A low polymerization step in which the olefins in the light fraction from which impurities have been removed are subjected to low polymerization using a catalyst; (3) The effluent from the low polymerization step is fractionated. (4) a hydrogenation process for hydrogenating the fractionated kerosene/gas oil fraction; How to treat distillates. 2 Surface area 100-800m^2/g, average pore diameter 10
The method for treating heavy oil pyrolysis light fractions according to claim 1, wherein silica gel of ~150 Å is used as an adsorbent. 3. The method for treating heavy oil pyrolysis light fractions according to claim 1, wherein the catalyst used in the low polymerization step is amorphous silica alumina or zeolite.