JPH1176809A - Amine-bearing adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorptive function suitable for industrial use by using an adsorbent comprising a porous inorganic support and a secondary amine and controlling the numerical value of the ratio of the surface area and the volume of the adsorbent within a specified range. SOLUTION: This adsorbent is produced by depositing a secondary amine on a porous inorganic support. As the porous inorganic support, a composition which is generally expressed as an inorganic oxide such as silica, alumina or the like is used. As the secondary amine, for example, diethanolamine, diisopropanolamine or the like is used. The more the amine is deposited, the more the surface of the support is covered and consequently, the surface area of the adsorbent becomes small. The aminebearing adsorbent, therefore, is made to have a surface area per 1 cc within a specified range. In other words, the ratio of [surface are (m<2> /g)]/[volume (cc/g)] is controlled to be 1-70 m<2> /cc, preferably 3-70 m<2> /cc, and further preferably 3-50 m<2> /cc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an adsorbent. In particular, the present invention relates to an adsorbent that selectively adsorbs organic sulfur compounds in a gas and is preferably used for removing organic sulfur in a gas.

[0002]

2. Description of the Related Art Adsorbents in which a secondary amine is supported on a porous carrier are already known. It is also known that such amine-supported adsorbents are used for removing organic sulfur compounds in gases. For example, JP-A-49-22375 and JP-A-1-123614 disclose that a gas containing an organic sulfur compound such as carbon disulfide is filled with an adsorbent in which a secondary amine is supported on activated carbon or another porous carrier. A method is disclosed for feeding to a bed to remove organic sulfur compounds in a gas.

[0003]

The mechanism by which the amine-supported adsorbent adsorbs organic sulfur is considered to be based on the reaction of an amine with an organic sulfur compound (for example, carbon disulfide) as represented by the following formula (1).

[0004]

Embedded image 2R ₂ NH + CS ₂ → (R ₂ N—CS ₂ ) ⁻ (R ₂ NH ₂ ) ⁺ (1)

[0005] Accordingly, it is expected that the larger the amount of amine carried, the larger the amount of adsorption, and the more preferable as an adsorbent. However, according to the study of the present inventors, it is considered that the larger the amount of amine supported, the larger the theoretical adsorption amount, and the longer the life of the adsorbent is. It has been found that the speed becomes slow and the adsorption rate (the ratio of the adsorbed sulfur compound) decreases, and therefore, those having a large amount of amine carried are not necessarily adsorbents having excellent adsorption performance. Thus, the above-mentioned known document does not teach at all about the relationship between the amount of amine carried and the life and adsorption rate of the adsorbent.

The present invention has been made in view of such circumstances, and has as its object to provide an amine-supported adsorbent having an adsorption performance suitable for industrial use.

[0007]

Means for Solving the Problems The present inventors have found that this object can be achieved by adjusting the surface area per volume of the amine-supported adsorbent, and completed the present invention. That is, the gist of the present invention is an adsorbent in which a secondary amine is supported on a porous inorganic carrier, and the ratio of the “surface area (m ² / g)” to the “volume (cc / g)” of the adsorbent. Is 1 to 70
(M ² / cc).

Hereinafter, the present invention will be described in detail. According to the study by the present inventors, in the amine-supported adsorbent,
As the amount of amine carried increases, the theoretical adsorption amount increases, and at the same time, the surface of the carrier is covered with the amine, and the surface area of the adsorbent decreases. The surface area of the adsorbent is 1 per cc of adsorbent
When it is less than m ² , the adsorption speed becomes extremely slow, and the performance of the adsorbent which can be industrially used is not exhibited. On the other hand, when the amount of amine carried is too small, the life as an adsorbent is short, and it cannot be used industrially. The present invention has succeeded in obtaining an amine-supported adsorbent having excellent adsorption performance by controlling the adsorption speed and adsorbent life by keeping the surface area per 1 cc in a specific range.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the porous inorganic carrier used in the adsorbent of the present invention, those having a composition usually represented as an inorganic oxide are preferable. Specific examples include silica, alumina, silica-alumina, titania, zeolite, and the like. Particularly, silica or alumina is preferable.
The porous inorganic carrier preferably has a pore volume of 0.1 to 2 ml / g, more preferably 0.2 to 1.5 ml / g, as measured by a mercury intrusion method. If the pore volume is small, the amount of the secondary amine to be carried becomes small, and a high-performance amine-supported adsorbent cannot be obtained. On the other hand, as the pore volume is larger, the amount of the secondary amine to be carried can be increased. However, when the pore volume is too large, the mechanical strength of the porous inorganic carrier is undesirably reduced.

The secondary amine supported on the porous inorganic carrier includes, for example, diethanolamine, diisopropanolamine, piperidine, morpholine, pyrrolidine, hexamethyleneimine, N-methylaminoethanol, N-aminoethylpiperazine, N- (2-aminoethyl) -1,3-propanediamine, dibenzylamine, dibutylamine, diphenylamine, diisobutylamine and the like. Preferred are dialkanolamines such as diethanolamine and diisopropanolamine. Further, two or more amines may be used in combination.

To carry the secondary amine on the porous inorganic carrier, the carrier is usually immersed directly in the amine or, if necessary, in an amine solution diluted with an appropriate solvent, or the amine or the amine solution is dissolved in the amine. After spraying on the carrier, it may be dried. The solvent is not particularly limited, and water or various organic solvents can be used depending on the amine used. Thus, the use of water as a solvent is preferable because it is safe and easy to handle and does not require equipment for treating solvent vapor in the drying step after loading. Therefore, when industrially producing an amine-supported adsorbent, it is preferable to use a water-soluble amine such as dialkanolamine as the secondary amine and use water as a solvent.

The amount of amine carried is related to the theoretical amount of adsorption of the adsorbent, that is, the service life, but differs depending on the type of amine used and the type of organic sulfur compound to be adsorbed. For industrial use, it is usually desirable that the amount of amine in 1 m ^{3 of the} amine-supported adsorbent is 100 kg or more. For example, when diethanolamine is used as the amine and the organic sulfur compound to be adsorbed is mainly composed of carbon disulfide, the adsorption mechanism is considered to follow the above formula (1), and the amine 100 k ³ in 1 m ^{3 of} the adsorbent is considered.
The theoretical amount of organic sulfur adsorbed in g is about 30 kg of sulfur.

As described above, the larger the amount of amine carried, the more
The surface of the carrier is covered with the amine, and the surface area of the generated adsorbent is reduced. Therefore, the amine-supported adsorbent of the present invention maintains the surface area per cc in a specific range, that is, its “surface area (m ² / g)” / “volume (cc / cc)”.
g) is required to be in the range of 1 to 70 (m ² / cc). "Surface area (m ² / g)" / "volume (cc / g)."
Is preferably 3 to 70 m ² / cc, more preferably 3 to 70 m ² / cc.
５０50 m ² / cc.

The ratio of the surface area to the volume of the adsorbent is controlled, for example, by controlling the surface area of the adsorbent by the amount of amine carried. Also, the amount of amine carried is
It can be controlled by the concentration of the amine solution, immersion time, drying conditions after loading, and the like. In the present invention, the surface area is measured by a BET method using nitrogen adsorption, and the volume is a numerical value measured using a measuring cylinder.

The amine-carrying adsorbent of the present invention is suitable for adsorbing and removing organic sulfur compounds in gas. Examples of the organic sulfur compound include carbon disulfide, carbonyl sulfide, mercaptan, and the like. For example, a gas containing these sulfur compounds such as a gas generated in a petroleum refining process can be used at normal pressure, normal temperature to 60 ° C., SV 500 to 20 By passing through a packed bed of an amine-supported adsorbent at 2,000 h ⁻¹ , sulfur compounds in the gas can be efficiently removed.

The size and shape of the adsorbent of the present invention are not particularly limited, and may be of any shape and size, such as granules and honeycombs, which are generally used as an adsorbent. When the amine-supported adsorbent is used for removing organic sulfur compounds in a gas, the adsorbent is preferably in the form of particles having a particle size of about 3 to 10 mm suitable for use as a packed bed.

[0017]

(Alumina simple substance)

(1) LD-350: average particle size 4.8 mm, pore volume by mercury method 0.21 ml / g (manufactured by Alcoa) (2) S-400: average particle size 6.4 mm, pore volume by mercury method 0.22ml / g (Alcoa)

[Method for measuring surface area] About 0.2 to 1 g of adsorbent
And the surface area per unit weight (m ² ) by the BET method (using an Okura Riken automatic surface area measuring device) by nitrogen adsorption.
/ G) was measured. [Measurement of volume] Approximately 100 g of the adsorbent was filled in a measuring cylinder and measured. [Amine loading rate] 10 ° C. in air between room temperature and 1000 ° C.
Calorimetric analysis (TG) at a heating rate of
The weight loss at a temperature of not less than ° C. was measured and calculated by the ratio to the weight of the adsorbent.

[Adsorption rate] An adsorption tube having an inner diameter of 6 mmφ is filled with 0.5 ml of an adsorbent, and a mixed gas (40 ° C.) of hydrogen and methane containing 21 ppm of carbon disulfide is added thereto under normal pressure.
The mixture was circulated at SV = 10000 h ^-1 for 5 minutes, and the value obtained by subtracting the ratio of the concentration of carbon disulfide in the outlet gas to the concentration of the inlet from 100% was shown.

Examples 1 to 3 and Comparative Examples 1 to 3 Five grams of alumina carrier S-400 was added to 200 cc of diethanolamine at 80 ° C., and the mixture was kept at 80 ° C. for 1 hour. The alumina support was taken out by filtration and dried at 110 ° C. to prepare an adsorbent. By changing the drying time, the amount of diethanolamine evaporated was changed, and an adsorbent having a changed diethanolamine carrying amount and surface area / volume was obtained. Table 1 shows the results of measuring the performance of the adsorbent.

Examples 4 to 6 and Comparative Examples 4 to 6 An adsorbent was prepared and its performance was measured in the same manner as in Example 1, except that the alumina carrier was LD-350. The results are shown in Table-2.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

As is clear from the examples, by controlling the surface area / volume of the adsorbent to a specific range according to the present invention, the adsorption rate and the theoretical adsorption amount (lifetime) suitable for industrial implementation are obtained.
Can be obtained.

Claims (3)

[Claims] An adsorbent comprising a secondary inorganic amine supported on a porous inorganic carrier, wherein the adsorbent has a “surface area (m ² / m ² )
g) "/ ratio" volume (cc / g) "is 1 to 70 (m ² /
cc) 2. The amine-supported adsorbent according to claim 1, wherein the porous carrier has a composition expressed as an inorganic oxide. 3. The amine-supported adsorbent according to claim 2, wherein the inorganic oxide is selected from silica, alumina, silica-alumina, and titania.