JPH01225694A - Process for purifying low-boiling cracking oil fraction - Google Patents

Abstract

PURPOSE:To efficiently perform simultaneous removal of nitrogen and oxygen compds. from low-boiling cracking oil fraction, by providing a silica gel having particular properties for use as an adsorbent and alternately performing the step of impurity adsorption in which the cracking oil fraction is brought into contact with the gel and the step of regeneration. CONSTITUTION:This process for purifying low-biling cracking oil fraction comprises a combination of the following steps (A) and (B). In step (A), low- biling cracking oil fraction is brought into with an adsorbent comprising a silica gel having a surface area of 100-800m<2>/g and an average pore diameter of 10-150Angstrom so as to effect simultaneous adsorption of impurities comprising nitrogen and oxygen compds. contained in the cracking oil fraction. In the step (B), the adsorbent contg. the impurities adsorbed thereto is regenerated by passing a regenerating gas at 100-600 deg.C. Of the above-mentioned silica gels, a silica gel having an SiO2 purity of at least 99wt.%, an Na2 content of up to 0.1wt.%, and an Fe2O3 content of up to 0.05wt.% is pref., because it is excellent in the simultaneous adsorption/removal capability of the impurities.

Description

Detailed Description of the Invention A9 Objective of the Invention
From n-min and pyrolysis light fractions, storage stability may be deteriorated,
It is related to the process of removing nitrogen and oxygen compounds, which are the source of moon viewing and act as catalyst poisons in subsequent catalytic reactions.

[EL-3] The light fiF77 obtained by decomposing heavy oil contains 10 to 11,000 p of nitrogen compounds and oxygen compounds as impurities.
However, these impurities cause various problems when the light distillate is used as gasoline, solvents, raw materials for chemicals, etc.

For example, they may impair the storage stability of these raw materials or become the source of bad odors.

Furthermore, one of the major problems is that it becomes a catalyst poison for the catalysts that process these light fractions.

This was a long-awaited, effective pretreatment technology.

Hydrorefining is a generally well-known pretreatment technique, and the cracked light fraction contains 20 to 50% of olefins that can be effectively used or recycled, and this can be simultaneously hydrogenated by hydrorefining. However, there is a problem that the decomposition process is easy, as there is a problem that the hydrogen is removed and therefore extra hydrogen is required for hydrogenation. There is no preferred method for removing WWJ compounds and oxygen compounds in the i fraction.

Therefore, various adsorption methods using suitable adsorbents have been proposed.

Usually, the substances that are particularly harmful to the tentacles are salt chloride (which was thought to be a chemical nitrogen compound), titanium oxide/silica (Japanese Patent Application Laid-Open No. 60-40195), silica alumina,
Adsorbents with acidic properties such as alumina are used for this purpose. In addition, it is proposed that acidic anhydride gas be adsorbed onto silica, zeolite has been done.

In addition, for oxygen compounds, ethers include silica gel (
Special Publication No. 55-44049), fermented titanium (↑1+j opening/closing No. 55-5752!1) for separating phenol isomers, and Y-type zeolite (Special Publication No. 6 [1-23095] for separating cresols). ) have been proposed as adsorbents.

As mentioned above, the adsorbents that have been proposed so far act independently on nitrogen compounds and oxygen compounds, and there is currently no treatment method that can remove both at the same time.

(2) The present invention provides a process that can simultaneously and efficiently remove nitrogen compounds and oxygen compounds from cracked light fractions.

8. Structure of the invention μII chart, L-ruta.

The process for purifying cracked light fractions according to the present invention is as follows.

The cracked light fraction has a surface area of 100 to 800 m2/g,
A process of simultaneously adsorbing impurities consisting of nitrogen compounds and oxygen compounds contained in the decomposed light fraction by contacting with an adsorbent made of silica gel having an average pore size of 10 to 150 people; It is characterized by a combination of steps for regeneration by flowing a regeneration gas at 100 to 600°C.

Note that the surface area is a value determined by the BET surface 8 & measurement method, and the average pore diameter is a value determined by a mercury intrusion method and a nitrogen adsorption method.

The nitrogen compounds contained in cracked light fractions include basic ones such as amines and pyridines, and non-basic ones such as nitriles such as benzonitrile and alkylvirols. However, since acidic or neutral substances such as phenols, cresols, and ethers are mixed in, it is difficult to remove nitrogen and oxygen compounds from raw materials containing these compounds at the same time.
Shiono, you can't choose an adsorbent based on that mindset.

Therefore, in order to adsorb both acidic substances and 112-based substances at the same time, it is necessary that the substance be an amphoteric substance that is neither drunk nor basic. Furthermore, in order to adsorb such substances to be adsorbed, it is necessary to have sufficient surface area and appropriate pore diameter.

As a result of intensive research from this point of view, the surface area of 100~8
It has been found that silica gel with a diameter of 00 m2/g and an average pore diameter of 10 to 150 has the effect of simultaneously adsorbing and removing both nitrogen compounds and oxygen compounds contained in the decomposed light fraction. The larger the surface area per meter of silica gel is, the better, and the upper limit is usually 800 m2/g for what can be done manually.

Among the above silica gels, N
Those containing 390.1% by weight or less of az O and 0.05% by weight or less of Fe2O3 have a particularly high ability to simultaneously adsorb and remove nitrogen compounds and oxygen compounds.

It was also discovered that the nitrogen compounds and oxygen compounds adsorbed on the silica gel described in L are easily desorbed at temperatures of 100 to 600°C, so it is possible to regenerate them by raising the temperature while flowing a regeneration gas. Ta.

With adsorbents selected based on the conventional acid/base concept, the bond between the nitrogen compound or oxygen compound and the adsorbent is strong, so
In the case of regeneration, the adsorbed substances are usually burned at high temperatures while waving the air, and the nitrogen compounds turn into NOx. Therefore, in order to prevent pollution, it is necessary to treat the exhaust gas of the regeneration process.

On the other hand, in the regeneration of the adsorbent of the present invention, by selecting conditions in which the adsorbed substances are directly desorbed without being burned, the nitrogen compounds do not become NOx, and can be used regardless of whether the exhaust gas of the regeneration process is treated or not. can be.

? It is also possible to recover the J compound as it is and use it for H1 use if it is safe.

The gas used to regenerate the adsorbent may be air, nitrogen, water vapor, hydrogen gas, or a mixture thereof.

The regeneration temperature of the adsorbent depends on the types of nitrogen compounds and oxygen compounds adsorbed, but it is preferably 100'C or higher, and in particular, it can be selected in the range of 100 to 600C depending on the gas used for regeneration. good. When using air as the gas for regeneration, the temperature should be set at 500° to suppress the generation of NOx.
C or lower is preferable.

Further, when using water vapor, the temperature is preferably 150°C or higher.

The regeneration time may be appropriately selected depending on the regeneration temperature and the desired degree of regeneration.

The present invention is a process for purifying cracked light fractions by using silica gel having the properties listed in L as an adsorbent and performing an adsorption step and a regeneration step alternately. By switching to and performing adsorption and regeneration,
It is possible to perform continuous operation.

The light distillate cracked in Kiba IJIJ may be any light distillate containing nitrogen compounds and oxygen compounds as impurities, and in particular light distillates obtained by cracking petroleum-based and coal-based insect oils. Suitable for a while.

The performance comparison of the silica gel used in the present invention and other adsorbents and the regeneration of the silica gel will be specifically explained below using Examples.

Example 1 and Comparative Example 1 0.5 g of various adsorbents were added to 300 ml of the cracked light fraction having the properties shown in Table 1, and after shaking at room temperature for 30 minutes, the total N and total 0 content was measured. Table 2 shows the results of determining the removal rate.

Table 2 also shows the relationship between the surface area of silica gel, N removal rate, and O removal rate, and the relationship between the average pore diameter of silica gel, N removal rate, and O removal rate.
The relationship with removal rate is shown in FIG. 1 and FIG. 21A.

In Figure 1, the horizontal axis is the surface area of silica gel (m2/g
), the vertical axis represents the removal rate (%) of N or 0, the ◯ mark indicates the O removal rate, and the symbol . indicates the N removal rate.

In Figure 2, the horizontal axis is the average pore diameter of silica gel (person) 1
The vertical axis represents the removal rate (%) of N or O, the O mark indicates the O removal rate, and . indicates the N removal rate.

From Table 2, Figures 1 and 2, the surface area is 100 to 800.
Silica gels A to E, which have an average pore diameter of 10 to 150 m2/g, can efficiently adsorb and remove both nitrogen compounds and oxygen compounds contained in the decomposed light fraction, and among them, the silica gels have a purity of 99%. It can be seen that silica gels A to C with a Na2O content of 1% or more, a Na2O content of 0.1% by weight or less, and a FezO* content of +4O, O5% by weight or less have particularly excellent ability to simultaneously adsorb and remove nitrogen compounds and oxygen compounds. .

Example 2 Nitrogen compounds and oxygen compounds in the pyrolysis light fraction were saturated and adsorbed onto 0.5 g of silica gel B shown in Table 2, and then dried.
It was reproduced under the conditions listed in Table 3.

The adsorbent produced by iIT was used in the same manner as in Example 1, and
The results using r are shown in Table 3.

In all cases in Table 3, no NOx was detected in the exhaust gas during regeneration.

Effect of 0 emission Nitrogen compounds and oxygen compounds can be effectively removed at the same time without hydrogenating the carbon dioxide in the light distillate.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the surface area of silica gel and the N removal rate and O removal rate, and FIG. 2 is a diagram showing the relationship between the 11 uniform pore diameter of silica gel and the N removal rate and O removal rate.

Claims (1)

[Claims] 1. The cracked light fraction has a surface area of 100 to 800 m^2/g,
A step of simultaneously adsorbing impurities consisting of nitrogen compounds and oxygen compounds contained in the decomposed light fraction by contacting with an adsorbent made of silica gel having an average pore diameter of 10 to 150 Å, and heating the adsorbent that has adsorbed the impurities to 100 to 600°C. A process for refining cracked light fractions, characterized by a combination of steps of regenerating by flowing regeneration gas through the process. 2. The process for purifying a cracked light fraction according to claim 1, which uses silica gel having a SiO_2 purity of 99% by weight or more, a Na_2O content of 0.1% by weight or less, and a Fe_2O_3 content of 0.05% by weight or less.