JP3442287B2 - Acid gas adsorbent - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an acidic gas adsorbent, and more specifically, it is an acidic gas adsorbent in which activated carbon carries an alkali metal carbonate, and is a petroleum-based cracked oil that can be reused mainly by decomposing plastic waste. It is used for adsorption removal of acidic gas such as hydrogen chloride decomposed and produced from vinyl chloride or vinylidene chloride.

[0003]

2. Description of the Related Art In recent years, there has been an increasing demand for recycling due to the serious problem of waste disposal. Regarding the waste plastic material, as disclosed in Japanese Patent Laid-Open No. 3-86791, a technique of thermally decomposing and recovering it as reusable petroleum-based cracked oil is drawing attention.

According to this method, the waste plastic material is first melted in the melting tank, then introduced into the thermal decomposition tank and thermally decomposed into a gas state, and then is lightened by the synthetic zeolite catalyst in the catalytic decomposition tank to be carbonized at a low boiling point. It becomes hydrogen gas, is cooled in a condenser and is recovered as petroleum-based cracked oil.

However, chlorine-containing plastics such as vinyl chloride resin and vinylidene chloride resin are usually mixed in the waste plastic material in an amount of 5 to 10% by weight. Therefore, hydrogen chloride is generated in the process of melting or thermal decomposition, corrosion of the device and poisoning of the catalyst in the catalytic cracking tank, and further when burning petroleum cracked oil obtained by this treatment method as a fuel in a boiler, There was a risk of corrosion of the boiler equipment. Hydrogen chloride generated in the melting step of the waste plastic material is neutralized and removed with water containing an alkali, but hydrogen chloride generated in the thermal decomposition process needs to be removed, and a countermeasure has been demanded.

As a countermeasure against this, Japanese Patent Laid-Open No. 3-86791 discloses an acidic gas adsorption tank for removing hydrogen chloride between the thermal decomposition tank and the catalytic decomposition tank, and the acidic gas is adsorbed and removed by calcium oxide filled inside. A method of doing so is disclosed.

However, when powdery or fine particles of calcium oxide are used as they are, high-boiling pyrolysis oil such as heavy oil, tar and wax contained in pyrolysis gas is deposited on the surface of calcium oxide. The voids between the particles of calcium oxide are blocked, and the ventilation resistance of the acid gas adsorption tank increases, making it difficult to purify the decomposed gas. Therefore, it is necessary to frequently replace the calcium oxide with the unreacted calcium oxide remaining, so that the performance of the acid gas adsorbent is not sufficiently exhibited, and there is a drawback that the running cost such as replacement cost becomes high. .

Therefore, in order to stably use calcium oxide for a long period of time, in JP-A-7-48576, there is an improvement plan in which an inorganic coarse particle tank is provided at least on the inlet side of an acid gas adsorption tank, and JP-A-7-62353. Discloses a method of blowing chlorine into a molten plastic in a raw material mixing tank to remove chlorine in the molten plastic.

Further, Japanese Patent Laid-Open No. 9-95678 discloses a method of using alumina particles in an acidic gas adsorption tank. However, in this method, it is necessary to remove the generated aluminum chloride as described in the publication.

However, only by these methods and their combination, it is possible to completely prevent the clogging of the voids between the adsorbent particles of the acidic gas due to the high boiling point pyrolysis oil and the deterioration of the carrier due to the high temperature hydrogen chloride or the basic substance. Is difficult. As a result, frequent replacement of the calcium oxide adsorbent or operation under conditions where the removal rate of hydrogen chloride is low is inevitable. Therefore, at present, only low-quality petroleum-based cracked oil with a large residual amount of hydrogen chloride is obtained.

The present inventors have previously described "catalyst" vol.39 No.4,
In 311 (1997), waste plastic that had been appropriately pre-treated and dried was batchwise charged into the melting tank, and after almost completely removing hydrogen chloride in the melting tank, it was batchwise transferred to the pyrolysis tank. An apparatus capable of significantly reducing the concentration of hydrogen chloride in the pyrolysis gas by sending it has been disclosed. However, if a small amount of hydrogen chloride remains in the pyrolysis gas, and it is difficult to maintain the function of the hydrogen chloride removal device for a long period of time and the adsorptivity of the removal device further decreases, There were many problems such as difficulty in taking out work.

[0012]

DISCLOSURE OF THE INVENTION In view of the problem of the step of removing an acidic gas such as hydrogen chloride generated in an apparatus for producing petroleum-based cracked oil from waste plastic material, the present invention considers a small amount of chloride in the pyrolysis gas. It adsorbs hydrogen and removes it almost completely, and it does not deteriorate even if the adsorbent is used for a long time.
The present invention aims to develop and provide an acid gas adsorbent that can be easily replaced when performance deteriorates.

[0013]

[Means for Solving the Problems] To solve these problems, the present inventors have found an adsorbent / removal agent for acidic gas such as hydrogen chloride, which is necessary to obtain a high-quality plastic cracked oil with little residual hydrogen chloride. Researched. First, JP-A-6-296858
Alkali metal carbonates such as potassium carbonate and sodium carbonate disclosed in Japanese Patent Laid-Open Publication No. 2003-242242 were tested on an acidic gas adsorbent supported on a porous carrier such as alumina, silica gel and zeolite. The dehydrochlorination performance of these adsorbents is good, and it is possible to obtain plastic cracked oil with a low hydrogen chloride content, but when used at temperatures above 300 ° C, the carrier gradually disintegrates and becomes a powder, and further adsorption It was found that the high boiling point cracked oil is deposited in the voids between the powder particles, increasing the ventilation resistance and making it difficult to use for a long time. Further, when cooled, the accumulated high-boiling point cracked oil is solidified, so that replacement work of the adsorbent becomes extremely difficult, and there is a problem in applicability to the production process.

Therefore, various adsorbents were further studied in order to develop an acid gas adsorbent which can maintain a high hydrogen chloride removing function for a long period of time and is easy to take out after use. The calcium oxide granulated product was expected to have a high acid gas adsorption function due to its high content of basic substances, but the test results showed that the amount of hydrogen chloride removed was significantly lower than the calculated adsorbable capacity. . It is considered that the adsorbent must have a property not only to simply increase the amount of the basic substance supported but also to effectively adsorb the acidic gas (Comparative Example 6).

Further, silica alumina and activated carbon supporting calcium oxide obtained by thermally decomposing an aqueous solution of calcium acetate adsorbed on silica alumina or activated carbon were also tested. As a result, the carrier was not pulverized, but the adsorbent preparation process was complicated and it was difficult to increase the amount of calcium oxide supported on the carrier, and the hydrogen chloride removal capacity could not be sufficiently increased (Comparative Example 2, 3).

It has long been known that activated carbon carrying an alkali metal carbonate can be used as an absorbent for acidic gases. However, when the present inventors adsorb and remove the acidic gas generated in the process of decomposing waste plastic materials to obtain petroleum-derived cracked oil, mainly hydrogen chloride, a wide range of coexisting high-boiling cracked oil and low-boiling cracked oil are decomposed. It was found that the relationship between the pore size and particle size of the oil and the adsorbent, and the voids between the particles had a great influence. Therefore, when the amount of supported carbonate in the alkali metal carbonate-activated carbon type adsorbent is out of a very limited range, the function of adsorbing / removing hydrogen chloride rapidly decreases, and the amount of benzene adsorbed on the activated carbon carrying carbonate is reduced. It has been found that the high adsorption function cannot be exhibited unless it is within a certain range. Furthermore, the particle size distribution of these and the adsorbent
The present invention has been reached as a result of examining the relationship with (filling specific gravity) and the like.

That is, alkali metal carbonate 10 is added to activated carbon.
The amount of benzene adsorbed is 20% or more and 40% or less, and the filling specific gravity is 0.4.
It is an acid gas adsorbent in the process of producing petroleum-derived cracked oil from plastic, which is 0 g / ml or more and 0.60 g / ml or less.

Here, the filling specific gravity is more preferably 0.45 g / ml or more, and potassium carbonate is more preferable as the alkali metal carbonate. Regarding the particle size distribution of the adsorbent particles, it is more preferable that the weight ratio of the adsorbent particles having a particle size of 0.500 mm or more and 4.75 mm or less is 95% or more, and further, if the acidic gas in the exhaust gas is hydrogen chloride. Is more suitable for.

The present invention will be described in detail below.

In the present invention, it is necessary to use an acidic gas adsorbent obtained by supporting activated carbon with an alkali metal carbonate. The activated carbon used as a carrier here generally has a large surface area of several 100 m ² or more per 1 g, and can be widely used as long as it is a carbon material exhibiting high adsorptivity. As the raw material of the activated carbon, a charcoal such as coconut shell or wood or coal is usually used, but any may be used. Among these, coconut shells, which can provide activated carbon with high hardness, are more preferable. The activation method is also steam or carbon dioxide at high temperature or zinc chloride,
It may be obtained by any method such as treatment with phosphoric acid or concentrated sulfuric acid.

Although the shape of crushed coal or granular coal is effective, it can be used as granulated coal in terms of pressure loss, replacement, etc., for example, spherical, columnar, needle-shaped and the like. Granulated coal is added to 100 parts of carbon material according to the conventional method.
It is adjusted by adding ~ 60 parts of petroleum pitch or coal tar as a binder, activating after mixing and molding. Activated carbon is a peculiar substance that has extremely excellent adsorptivity as a non-polar adsorbent, and exhibits high adsorptivity for almost all gaseous or liquid substances.

The acidic gas adsorbent of the present invention must be activated carbon loaded with an alkali metal carbonate in an amount of 10% by weight or more and 30% by weight or less. Since the inside of the pores of activated carbon is hydrophobic in nature, it is easier to adsorb heavy oil, tar, wax and other high boiling point cracked oil contained in pyrolysis gas than acid gases such as hydrogen chloride, so the amount of carbonate carried If less than 10% by weight, the ability to neutralize acid gases such as hydrogen chloride in the thermal decomposition gas of the waste plastic material becomes insufficient, and the adsorption performance of acid gas is considered to be reduced.

Further, even if the supported amount is increased to 30% by weight or more, not only is the improved supported amount of the acidic gas such as hydrogen chloride for the increased supported amount, but the removal performance of hydrogen chloride and the like in the decomposed gas Performance drops more rapidly. It is presumed that this is because the pores of the activated carbon are covered by supporting a large amount of carbonate, and the remaining pores are easily blocked by the adsorption of a small amount of high boiling point cracked oil. If the amount of supported carbon is further increased, the step of supporting the carbonate becomes complicated, and the excessive carbonate may be powdered and fall off, resulting in clogging of the acid gas adsorption tank. From these points, the supported amount of the alkali metal carbonate is an important requirement of the present invention, more preferably 15% by weight or more and 20% by weight or less.

The type of alkali metal is not particularly limited, and any of them can be used. For example, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate and the like. Of these, potassium carbonate is more preferable because it has a high solubility in water, is easy to support on activated carbon, and is highly safe.

The lower limit of the benzene adsorption amount of the adsorbent of the present invention is
20% and the upper limit needs to be 40%. The benzene adsorption amount measured under a certain condition is widely used as an index of the pore volume of the activated carbon adsorbent. Since the inside of the pores of activated carbon is hydrophobic in nature, it has the property that the high boiling point cracked oil such as heavy oil, tar, wax contained in the pyrolysis gas is more easily adsorbed than the acidic gas such as hydrogen chloride. Therefore, in order to prevent pore clogging due to adsorption of the high boiling point cracked oil, it is necessary to have an appropriate pore volume. When the amount of benzene adsorbed is less than 20%, a small amount of high boiling point cracked oil tends to cause pore blockage, and when the amount of adsorbed benzene exceeds 40%, the filling specific gravity decreases, so the adsorption capacity for acidic gases such as hydrogen chloride decreases. A tendency to do is recognized. From these viewpoints, the benzene adsorption amount is more preferably 25% or more and 37% or less.

The lower limit of the packing specific gravity of the adsorbent of the present invention is 0.40 g.
/ ml, the upper limit must be 0.60 g / ml. Filling specific gravity
When it becomes 0.40 g / ml or less, the adsorbing function declines because the amount of hydrogen chloride adsorbed in a fixed volume decreases. Therefore, the packing density of the adsorbent is more preferably 0.45 g / ml or more. Further, if the filling specific gravity is 0.60 g / ml or more, pores are likely to be clogged by the high boiling point cracked oil, and a sufficient acid gas adsorption function cannot be exhibited.

When the acidic gas adsorption tank is filled with the adsorbent of the present invention and used, it is preferable that the weight ratio of the activated carbon particles having a particle size of 0.50 mm or more and 4.75 mm or less is 95% or more. The result was obtained. Further, it is more preferable that the particle size be 1.00 mm or more, and it is more preferable that the particle size be 3.35 mm or less. According to the study by the present inventors, if the particle size is small, it becomes difficult to increase the amount of treated gas, so that economical operation cannot be performed, and if the particle size is large, the surface of the acid gas adsorbent is adsorbed by the high boiling point cracked oil. Is easily covered, and the adsorption performance of acidic gases such as hydrogen chloride that correlates with the content of alkali metals is not exhibited.

Here, if the materials of the activated carbon particles are all the same and the shapes are the same or similar, that is, if the particle size distribution is also the same, the filling specific gravity of the activated carbon and the average particle size have a constant relationship. It should be. However, in reality, since the material, the particle size distribution, and the particle shape are different from each other, it is considered that it cannot be limited only by the packing specific gravity.

The acid gas adsorbent of the present invention is used for adsorbing / removing the acid gas generated in the process of producing petroleum cracked oil from plastic. Although the raw material plastic is not particularly limited, it is a waste plastic material that is mainly treated as a part of waste treatment. here,
The "process of producing petroleum-based cracked oil from plastic" is a process of cracking the plastic to obtain cracked oil consisting of crude oil fractionation or cracked components thereof or components contained in petrochemical intermediates, etc. It is widely applied and is not particularly limited. At present, many processes including thermal decomposition and catalytic decomposition using a catalyst are adopted. The cracked oil is an oil that is liquid at room temperature, such as a mixture of gasoline, kerosene, and light oil,
Since it has a low chlorine content, it can be used as fuel for boilers, heating furnaces, etc.

The waste plastic material is usually mixed with 5-10% by weight of a chlorine-containing plastic such as vinyl chloride resin or vinylidene chloride resin. Therefore, hydrogen chloride decomposed in these processes is generated, causing corrosion of the equipment, poisoning of the catalyst in the catalytic cracking tank, and corrosion of the boiler equipment when the obtained petroleum cracked oil is burned in the boiler as fuel. There is a risk. The acidic gas adsorbent of the present invention is mainly used for adsorbing / removing acidic gas such as hydrogen chloride generated in these steps. From the composition of these decomposed gases, hydrogen chloride in the acidic gas to be adsorbed and removed by the adsorbent of the present invention is the most important object.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The mode of use of the acidic gas adsorbent of the present invention is not particularly limited, but a preferred mode is that in a process including melting, thermal decomposition and catalytic catalytic decomposition of a plastic material, a thermal decomposition tank and catalytic decomposition are used. It is used by filling an acid gas adsorption tank installed between the tanks. Hereinafter, the present invention will be described more specifically with reference to examples.

[0032]

[Example] (Example 1) Activated carbon (Kuraray Chemical Co., Ltd.)
Manufactured by Kuraray Coal GG), which absorbs an aqueous solution of potassium carbonate and then repeats drying to carry 15% by weight of potassium carbonate (hereinafter, simply referred to as%) and ash content of 18.4.
%, The weight ratio of activated carbon particles with a particle size of 1.40 to 3.35 mm is 98.1%
Thus, an adsorbent having a benzene adsorption amount of 27.6% and a packing specific gravity of 0.527 g / ml was obtained.

A melting step of a plastic material, a pyrolysis step,
Using a pilot plant of petroleum cracked oil production equipment including an oxidizing gas adsorption process and a catalytic cracking process using a catalyst, the acidic gas adsorbent 30 k
A waste plastic material containing about 10% of vinyl chloride resin was treated by filling g, and a production test of petroleum cracked oil was conducted.
In this test, 831.5 kg of waste plastic material could be treated before the first hydrogen chloride was detected from the outlet of the acid gas adsorption tank. Until then, the amount of hydrogen chloride generated from the thermal decomposition process was 2.41.
Since it is estimated to be kg, the amount of hydrogen chloride adsorbed and removed in the acid gas adsorption tank corresponds to the calculated adsorbable amount. Further, although the operation was continued in a state where hydrogen chloride leaked from the adsorption tank, no trouble was found in the solidification and removal work of the adsorbent. Further, the results of the hydrogen chloride aeration test are shown in FIG. The breakthrough time was 57 minutes.

In the above-mentioned examples and the following examples and comparative examples, the potassium carbonate content of the activated carbon is shown by the value calculated by the method of preparing the adsorbent. As an analysis method, it can be determined by ion chromatographic analysis of a solution extracted with distilled water at room temperature for 60 minutes, and it has been confirmed that the above calculated value agrees with this analytical value within the range of analytical error.

The ash content, particle size, benzene adsorption amount, and packing specific gravity of the adsorbent are values determined by JIS-K1474 "Granular activated carbon test method". That is, the ash content is obtained from the weight of the ash remaining after burning the activated carbon in the crucible in high temperature air, the particle size is obtained from the weight of the adsorbent particles remaining on each sieve after sieving, and the benzene adsorption amount is determined by the adsorbent. It was calculated from the weight increase before and after adsorbing benzene under a predetermined condition, and the packing specific gravity was calculated from the weight when packed in a 100 ml graduated cylinder while vibrating.

The amount of adsorbed hydrogen chloride was determined by placing the adsorbent in a glass desiccator, injecting hydrochloric acid, and measuring the concentration with a detector tube 24 hours at 25 ° C. Hydrochloric acid neutralization amount is the adsorbent
After mixing 10.0 g with 50 ml of distilled water for 30 minutes, filter and filter
The amount of hydrochloric acid (ml) was determined when 10 ml was neutralized and titrated with 0.1 N hydrochloric acid. The hydrogen chloride aeration test was performed by filling an adsorbent in a 20 mmΦ x 50 mm column, 20 ° C, relative humidity 50%, column inlet concentration 5000
The concentration at the column outlet when aerated with ppm at a gas flow rate of 500 ml / min / cm ² was measured with a detector tube. The breakthrough time of the hydrogen chloride aeration test was the time when the outlet concentration exceeded 10% of the inlet concentration.

Example 2 By the same operation as in Example 1, the amount of potassium carbonate carried was 20%, the ash content was 21.8%, and the particle size was 1.40 to 3.35.
An acid gas adsorbent having a weight ratio of activated carbon particles of 99.4%, a benzene adsorption amount of 28.2% and a packing specific gravity of 0.535 g / ml was obtained.

The acid gas adsorption tank was filled with the adsorbent obtained above, and about 10 parts of vinyl chloride resin was used in the same manner as in Example 1.
% Of the waste plastic material was processed to obtain petroleum cracked oil. It was possible to treat 870.0 kg of waste plastic material before hydrogen chloride was detected in the outlet gas of the acid gas adsorption tank. Even if the content of potassium carbonate was increased, the amount of the waste plastic material that could be treated was not improved as much as that of Example 1 in the adsorption performance corresponding to the increased amount of the carried carbonate. At this time, the amount of hydrogen chloride generated from the thermal decomposition tank was estimated to be 2.53 kg, which was about 80% of the calculated adsorbable capacity.

(Example 3) Activated carbon used in Example 1 (Kuraray Chemical Co., Ltd., trade name "Kuraray Coal GG") was reactivated to obtain activated carbon, and an aqueous potassium carbonate solution was absorbed and dried to obtain potassium carbonate. Loading amount 13%, ash content 14.6%, particle size 1.
An adsorbent having a weight ratio of activated carbon particles of 70 to 3.35 mm of 97.6%, a benzene adsorption amount of 35.7% and a packing specific gravity of 0.483 g / ml was obtained. The adsorbed amount of hydrogen chloride and the neutralized amount of hydrochloric acid of this adsorbent were 0.113 g / g and 41.19 ml / 10 g, respectively.

Using the pilot plant of the petroleum-based cracked oil manufacturing apparatus described in Example 1, an acid gas adsorption tank was filled with 2 kg of the adsorbent obtained above, and a vinyl chloride resin was used.
A test was conducted to remove hydrogen chloride in the gas generated when 0.5 kg, kerosene 1.9 kg, and light oil 7.6 kg were heated in a thermal decomposition tank. The amount of hydrogen chloride adsorbed in the acid gas adsorption tank is 137.3 g / 2kg
And almost corresponded to the calculated value of the adsorbable capacity. After the test, the adsorbed amount of hydrogen chloride and the neutralized amount of hydrochloric acid of the adsorbent are respectively
The values were 0.001 g / g (residual performance 1%) and 0.36 ml / 10g (residual performance 0.9%).

Example 4 As in Example 3, the amount of potassium carbonate supported was 15%, the ash content was 16.1%, and the weight ratio of the activated carbon particles having a particle size of 1.70 to 3.35 mm was 97.5%.
Activated carbon with 35.3% and a packing specific gravity of 0.502 g / ml was obtained. The adsorbed amount of hydrogen chloride and the neutralized amount of hydrochloric acid of this adsorbent were 0.12 each.
It was 5 g / g and 43.27 ml / 10 g.

As in Example 3, a pilot plant of a petroleum-based cracked oil production apparatus was used, an acid gas adsorption tank was filled with the adsorbent obtained above, and gas generated in the same manner as in Example 3 was used. A hydrogen chloride removal test was conducted. The amount of hydrogen chloride adsorbed in the acid gas adsorption tank was 137.3 g / 2 kg, which was almost equivalent to the calculated adsorbable capacity. After the test, the amount of adsorbed hydrogen chloride and the amount of neutralized hydrochloric acid of the adsorbent were 0.001 g / g (residual performance 1%) and 0.25 ml / 10 g (residual performance 0.6%), respectively.

Example 5 The same procedure as in Example 3 except that sodium carbonate was used instead of potassium carbonate, the amount of sodium carbonate supported was 12%, the ash content was 12.3%, and the particle size was 1.70 to 3.
An activated carbon having a weight ratio of 35 mm adsorbent particles of 98.1%, a benzene adsorption performance of 27.0% and a packing specific gravity of 0.527 g / ml was obtained. The adsorbed amount of hydrogen chloride and the neutralized amount of hydrochloric acid of this adsorbent were 0.128 g / g and 52.70 ml / 10 g, respectively.

A gas produced in the same manner as in Example 3 was filled with the adsorbent obtained in the above in an acid gas adsorption tank using a pilot plant for petroleum cracked oil production equipment as in Example 3. A hydrogen chloride removal test was conducted. The amount of hydrogen chloride adsorbed in the acid gas adsorption tank was 137.2 g / 2 kg, which was almost equivalent to the calculated adsorbable capacity. After the test, the amount of adsorbed hydrogen chloride and the amount of neutralized hydrochloric acid of the adsorbent were 0.001 g / g (residual performance 1%) and 0.25 ml / 10 g (residual performance 0.6%), respectively.

Comparative Example 1 Alumina (Sumitomo Chemical Co., Ltd.)
Manufactured by NKH 1-24) after adsorbing an aqueous solution of potassium carbonate,
Drying and loading of potassium carbonate 26%, filling specific gravity 0.790 g / ml
Of alumina was obtained. The adsorbent thus obtained was used for acid gas adsorption.

50.4 kg of the adsorbent obtained above was filled in an acidic gas adsorption tank in the same manner as in Example 1, and a waste plastic material treatment test was conducted using a pilot plant of a petroleum-based cracked oil production apparatus. . The processing amount of waste plastic material until hydrogen chloride is detected in the outlet gas of the acid gas adsorption tank is
It was good at 1,308 kg, but the adsorbent deteriorated and solidified, making replacement work difficult, and it cannot be used in actual manufacturing equipment. The results of the hydrogen chloride aeration test are shown in FIG. The breakthrough time was 15 minutes.

(Comparative Example 2) Silica alumina (Neobead SA, manufactured by Mizusawa Chemical Co.) was adsorbed with an aqueous calcium acetate solution, dried and pyrolyzed to carry 6% of calcium oxide, and a specific gravity of 0.806 g / ml of silica alumina. Got The silica alumina thus obtained was used as an acid gas adsorbent.

51.4 kg of the adsorbent obtained above was filled in an acidic gas adsorption tank in the same manner as in Example 1, and a treatment test of the waste plastic material was conducted using a pilot plant of a petroleum-based cracked oil production apparatus. . 167.5 kg of waste plastic material could be treated without leaking hydrogen chloride from the acid gas adsorption tank outlet.However, when waste plastic material was added, hydrogen chloride gas was detected from the acid gas adsorption tank outlet and the acid gas adsorption capacity was increased. It was insufficient. The results of the hydrogen chloride aeration test are shown in FIG. The breakthrough time was 2 minutes.

Comparative Example 3 Activated carbon (Kuraray Chemical)
After adsorbing an aqueous solution of calcium acetate on the product name "Kuraray Coal GG" manufactured by K.K., it is dried and decomposed by heating to have a calcium oxide loading of 9%, ash content of 11.4%, and a particle size of 1.70-4.75 mm. The weight ratio is 98.2%, and the benzene adsorption amount is 27.4.
%, And an adsorbent having a packing specific gravity of 0.495 g / ml was obtained.

66 kg of the adsorbent obtained above was filled in an acidic gas adsorption tank in the same manner as in Example 1, and a treatment test of the waste plastic material was conducted using a pilot plant of a petroleum-based cracked oil production apparatus. 422 kg of waste plastic material could be processed without leaking hydrogen chloride from the acid gas adsorption tank outlet, but when additional waste plastic material was added, hydrogen chloride gas was detected from the acid gas adsorption tank outlet, and the acid gas adsorption capacity was insufficient. Was enough. Figure 1 shows the results of the hydrogen chloride aeration test.
Shown in. The breakthrough time was 11 minutes.

Comparative Example 4 Activated carbon (Kuraray Chemical
(Kuraray Coal GG, manufactured by Co., Ltd.) is adsorbed with an aqueous potassium carbonate solution and then dried to have a potassium carbonate content of 8
%, Ash content 9.4%, weight ratio of activated carbon particles with a particle size of 1.70 to 4.75 mm is 96.9%, benzene adsorption amount 26.6%, packing specific gravity
0.578 g / ml of adsorbent was obtained.

The adsorbent obtained above was filled in an acidic gas adsorption tank in the same manner as in Example 1, and a waste plastic material treatment test was conducted using a pilot plant of a petroleum-based cracked oil production apparatus. However, the hydrogen chloride gas was detected from the outlet of the acid gas adsorption tank almost at the same time when the cracked oil was produced, so the test was stopped. The results of the hydrogen chloride aeration test are shown in FIG. The breakthrough time was 37 minutes.

(Comparative Example 5) Activated carbon (Kuraray Chemical)
(Kuraray Coal GG, manufactured by Co., Ltd.) is adsorbed with an aqueous solution of potassium carbonate and then dried to repeat 40% potassium carbonate loading, 42.8% ash content, and 1.40 to 3.35 mm particle size.
The weight ratio of activated carbon particles is 97.2%, and the amount of benzene adsorbed
An adsorbent with 10.2% and a packing specific gravity of 0.618 g / ml was obtained.

The adsorbent obtained above was filled in an acid gas adsorption tank in the same manner as in Example 1, and a treatment test of a waste plastic material was conducted using a pilot plant of a petroleum-based cracked oil production apparatus. However, the hydrogen chloride gas was detected from the outlet of the acid gas adsorption tank almost at the same time when the cracked oil was produced, so the test was stopped.

Comparative Example 6 Activated carbon (Kuraray Chemical)
(Kuraray Coal GG, manufactured by Co., Ltd.) is repeatedly dried by adsorbing an aqueous solution of potassium carbonate and then carrying 34% potassium carbonate, 36.4% ash, and 1.40 to 3.35 mm in particle size.
The weight ratio of activated carbon particles is 97.0%, and the amount of benzene adsorbed
An adsorbent with 20% and a packing density of 0.570 g / ml was obtained.

The adsorbent obtained above was filled in an acid gas adsorption tank in the same manner as in Example 1, and a treatment test of a waste plastic material was conducted using a pilot plant of a petroleum-based cracked oil production apparatus. 215.5 kg of waste plastic material could be treated before hydrogen chloride was detected from the outlet of the acid gas adsorption tank for the first time.

Comparative Example 7 Activated carbon (Kuraray Chemical
(Kuraray Coal GG, manufactured by Co., Ltd.) is adsorbed with an aqueous solution of potassium carbonate and dried to carry 5% of potassium carbonate,
The ash content is 5.4%, and the weight ratio of activated carbon particles with a particle size of 1.40 to 3.35 mm is
95.5%, benzene adsorption amount 42.0%, packing specific gravity 0.45
0 g / ml of adsorbent was obtained.

The adsorbent obtained above was filled in an acid gas adsorption tank in the same manner as in Example 1, and a treatment test of a waste plastic material was carried out using a pilot plant of a petroleum-based cracked oil production apparatus. 272.1 kg of waste plastic material could be treated before hydrogen chloride was detected from the outlet of the acid gas adsorption tank for the first time.

(Comparative Example 8) Regarding a calcium hydroxide granulated product in which the weight ratio of particles having a particle size of 1.40 to 3.35 mm is 95.4%,
The results of the hydrogen chloride aeration test are shown in FIG. Breakthrough time is 2
It was a minute.

The results of the hydrogen chloride aeration test of Example 1 and Comparative Examples 1 to 4 and 8 are shown in FIG. From this figure, the function of the adsorbent in which the activated carbon of Example 1 is supported by the alkali metal carbonate is far superior to the functions of the alumina-based, neo-bead-based and calcium oxide-based adsorbents of Comparative Examples 1 to 4 and 8. Is recognized.

FIG. 2 shows the relationship between the amount of potassium carbonate carried and the amount of hydrogen chloride adsorbed by the adsorbents used in Examples 1 to 4 and Comparative Examples 4 to 7. Moreover, in FIG. 3, Examples 1-4 and Comparative Examples 4-
The relationship between the benzene adsorption amount and the hydrogen chloride adsorption amount of the adsorbent used in Example 7 is shown. The data of the examples in these figures are:
The data of the comparative example are indicated by ◯.

In FIG. 2, the benzene adsorption amount of each data varies, and in FIG. 3, the carbonate loading amount of each data varies, so that the data of FIGS. 2 and 3 vary considerably. However, considering both the figures and the treatable amount until hydrogen chloride leaks when the waste plastic materials are treated in Examples 1 and 2 and Comparative Examples 4 to 7, a wide range existing in the treatment process is taken into consideration. The effects of high boiling point cracked oil and low boiling point cracked oil of
It is recognized that the adsorbent of the present invention has a significant criticality in the numerical limitation of the amount of alkali metal carbonate supported and the amount of benzene adsorbed.

[0063]

EFFECT OF THE INVENTION An adsorbent having a specific range of benzene adsorption amount and a packing specific gravity in which activated carbon is supported on a specific range of an alkali metal carbonate is used as an acidic gas adsorbent in the process of producing petroleum cracked oil from plastic. When used, it is stable to hydrogen chloride and basic substances at high temperatures and does not solidify or solidify the adsorption performance due to heavy boiling cracked oil such as heavy oil, tar and wax contained in the thermal cracked gas of plastic, It is effective for adsorbing and removing acid gases such as hydrogen chloride in pyrolysis gas.

[Brief description of drawings]

FIG. 1 shows the relationship between aeration time and hydrogen chloride concentration in a passing gas in a hydrogen chloride aeration test using the adsorbents obtained in Example 1 and Comparative Examples 1 to 3.

[Explanation of symbols]

1 Example 1 2 Comparative example 1 3〃 2 4 〃 3 5 to 8

FIG. 2 shows the relationship between the amount of potassium carbonate supported and the amount of hydrogen chloride adsorbed by the adsorbents obtained in Examples 1 to 4 and Comparative Examples 4 to 7.

FIG. 3 shows the relationship between the amount of supported potassium carbonate and the amount of adsorbed hydrogen chloride of the adsorbents obtained in Examples 1 to 4 and Comparative Examples 4 to 7.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hironori Inagawa 1-1-1 Nakanomiya Oike, Hirakata City, Osaka Prefecture Kubota Hirakata Factory (56) Reference JP-A-9-86914 (JP, A) JP 54-35188 (JP, A) JP 4-149015 (JP, A) JP 9-155187 (JP, A) JP 54-77290 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) B01J 20/20 B01D 53/68 C09K 3/00

Claims (4)

(57) [Claims] 1. An activated carbon carrying 10% by weight or more and 30% by weight or less of an alkali metal carbonate, a benzene adsorption amount of 20% or more and 40% or less, and a packing specific gravity of 0.40 g / ml or more, 0.60. Acid gas adsorbent in the process of producing petroleum-based cracked oil from plastic, which is less than g / ml. 2. The acidic gas adsorbent in the step of producing a petroleum cracked oil from the plastic according to claim 1, wherein the alkali metal carbonate is potassium carbonate. 3. The acid gas adsorbent in the step of producing a petroleum cracked oil from a plastic according to claim 1, wherein the weight ratio of the adsorbent particles having a particle size of 0.500 mm or more and 4.75 mm or less is 95% or more. 4. The acidic gas adsorbent in the step of producing a petroleum-based cracked oil from the plastic according to claim 1, wherein the acidic gas in the exhaust gas is hydrogen chloride.