JPH01123614A - Method for removing organic sulfur compound in gas - Google Patents

Abstract

PURPOSE:To carry out efficient desulfurization by bringing a gas contg. org. sulfur compds. into contact with an absorbent obtained by depositing a secondary amine or an org. solvent contg. the amine on a porous carrier having specified pore volume, mean pore diameter, and solid acid content. CONSTITUTION:The secondary amine such as dioleylamine or an org. solvent contg. the amine is deposited on the porous carrier of calcium silicate, magnesium silicate, silica, etc., having >=0.3cc/g pore volume, >=0.02mum mean pore diameter, and <=0.2mmol./g solid acid content to obtain an absorbent, and the absorbent is packed in a tower 1. A gas 5 contg. org. sulfur compds. such as CS2 is passed through the packed tower 1, and the sulfur compds. are absorbed by the absorbent. A gas 6 such as N2 heated by a heater 3 is then passed through the absorbent, hence the org. sulfur compds. are desorbed, and the compds. are treated in a sulfur compd. treating device 4.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to coke oven/blast furnace gas in the steel industry, various generated gases in the oil refining industry, and organic gases such as flue gas in various industries. The present invention relates to a method for removing sulfur compounds, and particularly to a method for removing sulfur compounds using a dry method.

<Prior art and its problems> Methods for removing organic sulfur compounds from gases such as coke oven gas include dry methods and wet methods.

As a wet method, one suitable for practical use is US Pat. No. 2,490,840.

In this method, sulfur compounds in the gas are removed by countercurrently contacting the gas with a solution containing an amine. However, when the gas contains carbon dioxide, secondary Since acid and alkali aqueous solutions are also required to recover amines, increasing the secondary amine concentration in the absorption liquid for the purpose of improving the removal rate of organic sulfur compounds reduces acid and alkali consumption according to the amount of carbon dioxide absorbed. The disadvantage is that the amount also increases.

A method that improves this problem is disclosed in Japanese Patent Publication No. 58-43132.

According to this method, a secondary amine recovery method that does not use an acid or alkaline aqueous solution is performed to treat the absorption reaction liquid. In any case, these wet methods have complicated processes,
It is economically very disadvantageous.

In the dry method, metal sulfides, metal oxides, molecular sieves, etc. are used to directly adsorb and remove, or hydrogen, water vapor, oxygen, etc. in the gas are used to convert them into easily removed compounds, which are then absorbed and adsorbed. However, this method requires treatment at a relatively high temperature of about 100 to 450°C or under pressure, and the influence of coexisting gases is large, making complete adsorption and regeneration of the absorbent difficult, and the adsorption amount is low. The big problem is that there aren't many. Among these dry methods, Japanese Patent Application Laid-Open No. 49-22375 is a relatively good method.

This method proposes that organic sulfur compounds are removed using a porous carrier carrying a secondary amine or its organic solvent solution as an absorbent. According to this, a porous carrier should be used as much as possible,
Looking at the amount of organic sulfur compounds absorbed using the activated carbon in the example, we found that the life of the absorbent material is short in practical terms, and even if regeneration is applied, the number of regeneration cycles is large, making it difficult to apply as an actual process. be. Furthermore, in the regeneration method, the absorbent material is washed with a secondary amine-containing solution under reduced pressure and at room temperature to 150°C, but there are problems such as waste liquid treatment, and it is difficult to carry out as an actual process. There is a problem that cannot be answered.

<Object of the invention> The present invention aims to solve the problems of the prior art described above, and is capable of absorbing as much secondary amine as an active substance as possible and retaining its activity for a long time. ,
That is, the present invention aims to provide a method for removing organic sulfur compounds from gas suspensions, which uses a carrier with a long life and can easily regenerate a lid absorbent material that is in an equilibrium absorption state.

<Structure of the Invention> The present inventor has proposed a method for removing organic sulfur compounds in a gas using an absorbent in which a carrier supports a secondary amine, etc.
In order to increase the absorption amount of organic sulfur compounds and extend the life of the absorbent material, it was found that it is effective to use a porous carrier with specific physical properties, and the present invention was developed based on this finding.

That is, the first aspect of the present invention is a porous carrier having a pore volume of 0.3 cc/g or more, an average pore diameter of 0.02 or more, and a solid acid content of 0.2 mmof/g or less;
The method is characterized by using an absorbent supporting a primary amine or an organic solvent solution containing a secondary amine, and bringing a gas containing an organic sulfur compound into contact with the absorbent to selectively absorb the organic sulfur compound. A method for removing organic sulfur compounds in gas is provided.

A second aspect of the present invention provides a porous carrier with a pore volume of 0.
．． Using an absorbent material in which a secondary amine or an organic solvent solution containing a secondary amine is supported on a carrier with an average pore diameter of 3 cc/g or more, an average pore diameter of 0.02 or more, and a solid acid amount of 0.2 mmo C/g or less. , by bringing a gas containing an organic sulfur compound into contact with the absorbent material to selectively absorb the organic sulfur compound, and then passing a gas containing no organic sulfur compound at a temperature of 50° C. or higher to the absorbent material. Provided is a method for removing organic sulfur compounds from a gas, which comprises removing the sulfur compounds absorbed by the absorbent material and reusing the absorbent material.

The present invention will be explained in detail below.

In order to solve the problem that the porous absorbent material supported with secondary amines, which has been conventionally used for gas purification, has a low absorption amount of organic sulfur compounds and has a short lifespan, it is necessary to simultaneously satisfy the following characteristics: It is necessary to use a carrier that supports

(1) The pore volume is large, (2) the average pore diameter is not small, and (3) the amount of solid acid (solid acidity) is not large. It is necessary to use a porous carrier within a certain numerical range.

To explain the above characteristics, first, the large pore volume leads to the possibility of absorbing a large amount of secondary amine, which has the activity of reacting and absorbing organic sulfur compounds in gas. In other words, a high liquid absorption property may lead to a large amount of organic sulfur compounds being absorbed, and therefore a long life.

The pore volume is 0.3 cc/g or more, preferably 3 cc/g or more. If it is less than 0.3 cc/g, the amount of amine that is an active substance supported will naturally decrease, and the theoretical amount of organic sulfur compounds absorbed will also decrease, which is disadvantageous.

Next, the reason why the average pore diameter is not small is that if the pore diameter is small, it is difficult for the secondary amine, which is an active substance, to be supported in the pores.

Further, even if the organic sulfur compound is supported, when the organic sulfur compound diffuses into the pores having a small pore diameter, the diffusion rate becomes slow, and it is considered that the active substance is difficult to effectively react with the organic sulfur compound.

The average pore diameter is preferably 0.02p or more and sulfur content 0.02p or more.
05μ or more. If it is less than 0.02 pm, as described above, not only the amount of amine supported will decrease, but also the reactivity with organic sulfur compounds will decrease.

Finally, the amount of solid acid (solid acidity) is not large.
Since the secondary amine, which is an active substance, is basic, if the amount of acid (acidity) in the supported carrier is large, the active amine will react with the carrier when supported, resulting in the dispersion state within the pores. There is a good possibility that the reactivity with organic sulfur compounds will decrease significantly as a result. Therefore, it is important that the solid acid amount (solid acidity) of the carrier is not large.

Regarding solid acid amount (solid acidity), 0.2 mmoj2
/g or less. o. If it exceeds 2 mmof/g, as mentioned above, the reactivity between the carrier and the amine becomes strong, and as the amount of solid acid increases, this tendency becomes stronger, and the reactivity with the organic sulfur compound decreases. Become.

Here, the amount of solid acid (solid acidity) refers to a value measured under the following conditions or a value equivalent thereto.

(1) Measuring device: Multipurpose calorimeter manufactured by Tokyo Riko (2) Measuring method: NH3 adsorption heat measurement (3) Pretreatment conditions: Exhaust treatment at 400°C (7 hours) Treatment vacuum degree: 1. OX 10-' Torr (4) Definition of acid site:
80 kJ/+oj! A point showing the above heat of adsorption is defined as an acid site (5) Acid amount: Heat of adsorption in (4) above 80 kJ/m
Acid amount is the amount showing ob or more (IIIIOJZ/g)
Expressed as

The carrier used in the present invention may be any carrier as long as it satisfies the above conditions, but it is preferable to select one among calcium silicate, magnesium silicate, silica, etc. that satisfies the above conditions.

Examples of secondary amines supported on the porous carrier include piperidine, morpholine, pyrrolidine, hexamethyleneimine, N-methylaminoethanol, N-aminoethylpiperazine, N-(2-aminoethyl)-1,3- Examples include propanediamine, jetanolamine, diisopropanolamine, dibutylamine, diphenylamine, diisobutylamine, and dibenzylamine.

These secondary amines are added to the carrier directly or as a solution in a solvent, preferably in an amount of 0.1 to 70% of the total weight.

Examples of the solvent used include hydrocarbon liquids such as creosote liquid, penzole, and naphtha, and aliphatic, alicyclic, or aromatic alcohols and ketones having about 1 to 10 carbon atoms.

The appropriate dose is about 1 to 10 times the volume of the carrier.

The reaction when organic sulfur compounds in gas are absorbed and desorbed by an absorbent containing a secondary amine is considered to be the following reaction.

Absorption reaction> 2R2NH+CS2→R2NC5H2NR2 Regeneration reaction> (It seems to be decomposed) The form of the amine after decomposition is unknown, but it is thought to be a secondary or tertiary amine containing some S.

The method for removing organic sulfur compounds from gas according to the present invention is carried out in the following steps using the above-mentioned absorbent.

This will be explained using the flowchart of the preferred embodiment shown in FIG.

First, a carrier having a pore volume of 0.3 cc/g or more, an average pore diameter of 0.021 m or more and a solid acid amount of 0.2 m mol/g or less, such as calcium silicate, magnesium silicate, or silica, is used as a second carrier. An absorbent material is prepared by appropriately supporting a class amine or an organic solvent solution thereof using known means.
The absorbent material is packed into a packed tower 1.

Next, the gas 5 containing the organic sulfur compound is brought to room temperature to 60° C. using the gas heating device 2 and introduced into the packed tower 1 .
Organic sulfur compounds in the gas are absorbed and removed by the absorbent in the packed tower 1.

Now, when the absorbent absorbs organic sulfur compounds up to the equilibrium absorption amount, a gas 6 that does not contain organic sulfur compounds (for example, N2, air, etc.) is heated to 50°C or higher using a heating device 3, and then 1. At this time, the organic sulfur compounds absorbed from the absorbent material are released.

Next, the gas discharged from the packed tower 1 is transferred to a sulfur compound treatment device 4.
and process it. The desorbed sulfur compounds will be described in the examples below, but since most of them are in the form of hydrogen sulfide, the treatment device 4 may be appropriately equipped with known means such as combustion treatment, hydrogen sulfide absorbing material, etc. Any filling device or the like may be used.

<Example> A more specific explanation will be given below with reference to Examples.

<Example 1. and Comparative Example> Carriers with different pore volumes, average pore diameters, and amounts of solid acid were selected to compare the absorption performance of carbon disulfide (C32), an organic sulfur compound.

The carrier used, its pore volume, average pore diameter, and amount of solid acid are shown in Table 1. Dioleylamine (R2NH; R=C+yl(3s
co) was impregnated.

are shown in Table 1.

The gas composition used in the test is shown in Table 2.

50 mg/Nrr of carbon disulfide, which is an organic sulfur compound, in the gas having the composition shown in Table 2? was used.

The carbon disulfide absorption test conditions were as follows.

(1) Absorbent average particle size: 0.7 mm (2) Gas flow rate: 0, I It/win (3
) Absorbent filling amount: 2 degrees (4) SV (space velocity): 3000H-' (5) Temperature:
25°C (6) Pressure Crab The normal pressure test results are shown in Figure 2.

Breakthrough point (breakthrough time) is the time from when the fluid starts flowing until the adsorbate first emerges from this layer when gas containing adsorbate is passed through a fixed bed filled with adsorbent at a constant speed. The breakthrough rate is the ratio of the outlet concentration to the inlet concentration.

Figure 2 clearly shows that silica and calcium silicate have good reactivity. In this test, the breakthrough rate was not 0% because it was conducted under conditions of a high SV value, but if it was conducted under a low SV value, the CS2 removal rate would naturally be 100% and the breakthrough rate would be 0%. The properties of the silica and calcium silicate used are as shown in Table 1, including pore volume, average pore diameter,
Both the amounts of solid acid were within the conditions for the carrier used in the present invention described above, demonstrating the superiority of the present invention.

<Example 2. and Comparative Example> Using calcium silicate, which was proven to be an excellent carrier in Example 1, an absorption test was conducted under conditions of a low Sv value. Iron oxides shown in Table 1 were used as carriers for comparison.

The test conditions were as follows, and the results are shown in Figure 3.

(1) Processing gas: gas shown in Table 2 (2) CS2 concentration in gas: 50 mg/Nrn'(
3) Absorbent average particle size: 8mm (4) Gas flow rate: 1427mln (5) Absorbent filling amount: 0.5J:L (6) SV (space velocity): 120H-1 (7) Temperature = 2
5° C. (8) Normal pressure The carrier was impregnated with the same dioleylamine as in Example 1, and the impregnation rate is shown in Table 1.

The plot (1)- in Figure 3 is calcium silicate;
Plot 2) shows iron oxide for comparison.

As shown in FIG. 3, when calcium silicate was used as a carrier, C52 was completely removed for 30 days.

On the other hand, for iron oxide, the removal rate was 90% during the initial period, but the removal rate after the 25th day decreased to about 50%. From the above, it was demonstrated that the calcium silicate according to the present invention has a long C52 absorption life.

<Example 3. > It was found that calcium silicate, which was proven to have a long cs2 absorption life in Example 2 above, could be regenerated and used repeatedly.

The test conditions are as follows.

(1) Absorption test conditions ■ Absorbent average particle size: o, 7 mm ■ Gas flow rate: 0, 3 f/mi, n ■ Absorbent filling amount: 2 relatives ■ sv (space velocity): 3000H-' ■ Temperature: 25
℃ ■ Normal pressure ■ CS2 concentration in gas: 50 mg/Nm' (2)
Regeneration test conditions 100tN2 was distributed through the absorbent material, 50mu/min,
I worked for 6hrfi. The concentration of sulfur compounds in the outlet gas at this time is H2S: 1.4 vo1%C32: 1300mg
/Nrn', CO5: 30mg/Nrd. Total sulfur content of sulfur compounds absorbed in the absorbent material (T-3
) is taken as 100%, the above regeneration results in 75%T-S
Minutes left.

The results of the test under the above conditions are shown in FIG.
As shown in FIG. 4, the C32 absorption rate was slightly slower when used twice after regeneration, but it was demonstrated that repeated reuse was possible.

<Effects of the Invention> According to the method for removing organic sulfur compounds from gas of the present invention, since a carrier with a specific numerical shape is used, organic sulfur compounds can be removed in a dry low temperature manner with a long carrier life. It can be recycled using easy recycling methods and has the effect of being able to be used repeatedly.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing one embodiment of the present invention. FIG. 2 is a graph showing the carbon disulfide absorption ability of the carrier. FIG. 3 is a graph showing the absorption capacity when calcium silicate and iron oxide are used as carriers. FIG. 4 is a graph showing absorption capacity due to regeneration. HikoFIG, 3 Number of days elapsed (days) C52) = J1 '? (Shi) O″′TI

Claims (2)

[Claims] (1) As a porous carrier, the pore volume is 0.3 cc/g or more, the average pore diameter is 0.02 μm or more, and the amount of solid acid is 0.2 m.
Using an absorbent material in which a secondary amine or an organic solvent solution containing a secondary amine is supported on a carrier of mol/g or less, a gas containing an organic sulfur compound is brought into contact with the absorbent material to remove the organic sulfur compound. A method for removing organic sulfur compounds in a gas, characterized by selective absorption. (2) As a porous carrier, the pore volume is 0.3 cc/g or more, the average pore diameter is 0.02 μm or more, and the amount of solid acid is 0.2 m.
Using an absorbent material in which a secondary amine or an organic solvent solution containing a secondary amine is supported on a carrier of mol/g or less, a gas containing an organic sulfur compound is brought into contact with the absorbent material to remove the organic sulfur compound. After selective absorption, the sulfur compounds absorbed in the absorbent are desorbed by passing a gas at 50°C or higher that does not contain organic sulfur compounds, and the absorbent can be reused. Characteristic method for removing organic sulfur compounds from gas.