Method for preparing solid amine gas adsorption material

Abstract

The present invention relates to a method for preparing a solid amine gas adsorption material. The method synthesizes a porous solid amine gas adsorption material that loads organic amine evenly. In the method, a certain amount of acidic gas is introduced while organic amine molecules are introduced into a silicate solution as template agents, which not only makes sizes of SiO.sub.2 pore channels homogeneous, but also makes organic amine molecules highly evenly distributed on a surface of SiO.sub.2. In addition, the acidic gas protects NH.sub.2 groups of organic amine, and avoids NH.sub.2 adhesion inactivation due to hydrogen bonding during the synthesis process of the material. The present invention also relates to a method for preparing a solid amine gas adsorption material after obtaining a silicate solution from fly ash. The solid amine gas adsorption material prepared has more stable and effective gas adsorption performance.

Claims

1. A method for preparing a solid amine gas adsorption material, comprising the steps of: 1) adding an organic amine to a silicate solution, introducing an acidic gas to the solution while stirring, until the pH value of the solution is 9 to 11, to obtain a SiO.sub.2 sol or gel precipitate; and 2) filtering off the SiO.sub.2 sol or gel precipitate from the above solution, and aging, drying, and dehydrating, to obtain a solid amine gas adsorption material.

2. The method according to claim 1, wherein the silicate solution is a sodium silicate solution and/or a potassium silicate solution.

3. The method according to claim 1, wherein the concentration of the silicate solution is 5 to 50 wt %.

4. The method according to claim 1, wherein the silicate solution is prepared by filtering the reaction mixture obtained by subjecting fly ash and an alkali solution to alkali fusion.

5. The method according to claim 4, wherein the source of the alkali in the alkali solution is selected from one or more of a group consisting of amino compounds, alkali hydrides, and alkali hydroxides.

6. The method according to claim 4, wherein fly ash and a 10 to 30 wt % alkali solution are subjected to alkali fusion according to a solid-liquid weight ratio of 1:1 to 1:5.

7. The method according to claim 4, wherein the alkali fusion reaction lasts for 30 to 120 min.

8. The method according to claim 4, wherein the alkali fusion reaction is carried out at a temperature between 30 and 120 C.

9. The method according to claim 1, wherein said acidic gas is selected from one or more of a group consisting of carbon oxides, sulphur oxides, nitrogen oxides, and sulphur hydrides.

10. The method according to claim 1, wherein said organic amine is selected from the group consisting of polyethyleneimine (PEI), tetraethylenepentamine (TEPA), ethylenediamine, butanediamine, hexanediamine, tris(2-aminoethyl)amine, acrylonitrile, cyanuric chloride, diisopropylethylamine, methyl acrylate, and mixtures thereof.

11. The method according to claim 1, wherein the ratio between the mass of the organic amine and the mass of the obtained solid amine gas adsorption material is from 1:10 to 6:10.

12. The method according to claim 1, wherein the flow rate of said acidic gas is 5 to 15 L/min.

13. The method according to claim 1, wherein aging, drying, and dehydrating are performed at a temperature between 100 and 120 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a synthesis process diagram of preparing a solid amine gas adsorption material with fly ash according to this invention.

(2) FIG. 2 shows a contrast diagram of adsorption properties between the solid amine gas adsorption material prepared in an example of this invention and the solid amine gas adsorption material prepared by the impregnation method.

(3) FIG. 3 is a scanning electron micrograph of PEI(45%)-SiO.sub.2 prepared in Example 2, therefrom the porous and high specific surface area profile of the adsorbent can be observed, thus enhancing the adsorption property for CO.sub.2.

SPECIFIC EMBODIMENTS

(4) This invention is further illustrated hereinbelow, however, the following examples are merely described to assist a person skilled in the art to better understand principles and essences of this invention, instead of setting any limitation on this invention.

(5) The properties and preparation method of the above adsorption material are illustrated hereinbelow by exemplary, rather than restrictive examples.

EXAMPLES

Example 1

Preparation of PEI(30%)-SiO2 Solid Amine Gas Adsorption Material

(6) Step (1): Preparing a Supernatant by Desiliconization of Fly Ash

(7) The fly ash used in this Example was obtained from some power plant of Shenhua Zhungeer, and the chemical components thereof were shown in Table 1.

(8) TABLE-US-00001 TABLE 1 Composition SiO.sub.2 Al.sub.2O.sub.3 CaO Fe.sub.2O.sub.3 MgO K.sub.2O TiO.sub.2 Other wt % 39.15 52.41 1.02 2.16 0.32 0.42 1.31 3.21

(9) 40 g of the above fly ash were dissolved in a 400 ml solution containing 15% by weight of sodium hydroxide at 90 C., to react for 90 min, and filtered to obtain a supernatant containing 6.72% by weight of Na.sub.2SiO.sub.3. Since K.sub.2O was contained in lattice, and thus could not be dissolved during the reaction, so that the solute in the supernatant was basically sodium silicate.

(10) Step (2): Loading Organic Amine

(11) 2.4 g polyethyleneimine (PEI) in a purity of 98% by weight were added to a 100 ml supernatant prepared in Step (1), carbon dioxide gas in a purity of 99% was introduced therein at a flow rate of 10 L/min while stirring. White flocculent SiO.sub.2 sol precipitate appeared when the pH of the solution was about 13. The introduction of CO.sub.2 continued until the pH was 10.

(12) Step (3): Aging and Drying

(13) The SiO.sub.2 sol precipitate was filtered and subjected to aging, drying and dehydrating at 110 C. to prepare a solid amine gas adsorption material PEI(30%)-SiO.sub.2. The ratio of the mass of the added organic amine to the total mass of the finally obtained solid amine gas adsorption material was about 30% (see Test example 1). The specific surface area of the adsorption material was 9.85 m.sup.2/g, the pore volume was 0.05 cm.sup.3/g, and the pore diameter was 11.02 nm.

Example 2

Preparation of PEI(45%)-SiO2 Solid Amine Gas Adsorption Material

(14) Step (1): Preparing a Supernatant by Desiliconization of Fly Ash

(15) The fly ash used in this Example was obtained from some power plant of Shenhua Zhungeer, and the chemical components thereof were shown in Table 1.

(16) TABLE-US-00002 TABLE 1 Composition SiO.sub.2 Al.sub.2O.sub.3 CaO Fe.sub.2O.sub.3 MgO K.sub.2O TiO.sub.2 Other wt % 39.15 52.41 1.02 2.16 0.32 0.42 1.31 3.21

(17) 100 g of the above fly ash were dissolved in a 400 ml solution containing 15% by weight of sodium hydroxide at 90 C., to react for 90 min, and were filtered to obtain a supernatant containing 16.8% by weight of Na.sub.2SiO.sub.3. Since K.sub.2O was contained in lattice, and thus could not be dissolved during the reaction, so that the solute in the supernatant was basically sodium silicate.

(18) Step (2): Loading Organic Amine

(19) 9 g polyethyleneimine (PEI) in a purity of 98% were added to 100 ml supernatant prepared in Step (1), carbon dioxide gas in a purity of 99% was introduced therein at a flow rate of 10 L/min while stirring. White flocculent SiO.sub.2 sol precipitate appeared when the pH of the solution was about 13. The introduction of CO.sub.2 continued until the pH was 10.

(20) Step (3): Aging and Drying

(21) The SiO.sub.2 sol precipitate was filtered and subjected to aging, drying and dehydrating at 112 C. to prepare a solid amine gas adsorption material PEI(45%)-SiO.sub.2. The ratio of the mass of the added organic amine to the total mass of the finally obtained solid amine gas adsorption material was about 45% (see Test example 1). The specific surface area of the adsorption material was 15.03 m.sup.2/g, the pore volume was 0.07 cm.sup.3/g, and the pore diameter was 17.78 nm.

Example 3

Preparation of TEPA(30%)-SiO2 Adsorption Material

(22) Step (1): Preparing a Supernatant by Desiliconization of Fly Ash

(23) The fly ash used in this Example was obtained from some power plant of Shenhua Zhungeer, and the chemical components thereof were shown in Table 1.

(24) TABLE-US-00003 TABLE 1 Composition SiO.sub.2 Al.sub.2O.sub.3 CaO Fe.sub.2O.sub.3 MgO K.sub.2O TiO.sub.2 Other wt % 39.15 52.41 1.02 2.16 0.32 0.42 1.31 3.21

(25) 200 g of the above fly ash were dissolved in a 400 ml sodium containing 15% by weight of sodium hydroxide at 90 C., to react for 90 min, and were filtered to obtain a supernatant containing 33.6% by weight of Na.sub.2SiO.sub.3. Since K.sub.2O was contained in lattice, and thus could not be dissolved during the reaction, so that the solute in the supernatant was basically sodium silicate.

(26) Step (2): Loading Organic Amine

(27) 12 g tetraethylenepentamine (TEPA) in a purity of 98% were added to 100 ml supernatant prepared in Step (2), carbon dioxide gas in a purity of 99% was introduced therein at a flow rate of 10 L/min while stirring. White flocculent SiO.sub.2 sol precipitate appeared when the pH of the solution was about 13. The introduction of CO.sub.2 continued until the pH was 9.

(28) Step (3): Aging and Drying

(29) The SiO.sub.2 sol precipitate was filtered and subjected to aging, drying and dehydrating at 110 C. to prepare a solid amine gas adsorption material TEPA(30%)-SiO.sub.2. The ratio of the mass of the added organic amine to the total mass of the finally obtained solid amine gas adsorption material was 30% (see Test example 1). The specific surface area of the adsorption material was 8.71 m.sup.2/g, the pore volume was 0.03 cm.sup.3/g, and the pore diameter was 9.36 nm.

Test Example 1

(30) A thermogravimetric analyzer was used to measure the organic amine load and the CO.sub.2 adsorption amount of the adsorption material prepared in Examples 1-3 by heating. After performing the adsorption-desorption cyclic operation for 20 times, variation in the organic amine load and the CO.sub.2 adsorption amount was observed, and test results thereof were shown in the following Table 3.

(31) The organic amine load=the mass of the loaded organic amine/the total mass of the solid amine adsorption material;

(32) CO.sub.2 adsorption amount (mg/g adsorption material)=the mass of the adsorbed CO.sub.2 (mg)/the total mass of the adsorption material (g).

(33) TABLE-US-00004 TABLE 3 After 20 times of CO.sub.2 First adsorption adsorption-desorption Organic CO.sub.2 adsorption Organic CO.sub.2 adsorption amine load amount (mg/g amine load amount (mg/g Examples Adsorption material (wt %) adsorption material) (wt %) adsorption material) Example 1 PEI(30%)-SiO.sub.2 29.8 61 28.1 49 Example 2 PEI(45%)-SiO.sub.2 45.2 122 43.2 99 Example 3 TEPA(30%)-SiO.sub.2 29.6 54 27.6 46

Test Example 2

(34) A thermogravimetric analyzer was used to measure, by heating, the organic amine load as well as the CO.sub.2 adsorption amount of the solid amine gas adsorption material prepared according to the method of Example 2 of this invention, and the solid amine gas adsorption material synthesized according to the traditional impregnation method. The results were shown in FIG. 2.

(35) The traditional impregnation method for synthesis of a solid amine gas adsorption material comprises: impregnating a silicon dioxide porous support in an ethanol solution of organic amine PEI, adsorbing or storing the ethanol solution of organic amine PEI in the support capillary, removing the redundant solution, drying, calcining, and activating.

(36) As shown by FIG. 2, when the PEI load of the solid amine gas adsorption material synthesized by the traditional impregnation method was 35 wt %, the maximum CO.sub.2 adsorption amount was 74 mg/g of the adsorption material. The solid amine gas adsorption material synthesized by the method of this invention enables organic amine to be dispersed more evenly on the SiO.sub.2 support, when the PEI load thereof was 45 wt %, the maximum CO.sub.2 adsorption amount could be up to 122 mg/g of the adsorption material.

(37) The terms and expressions used in this description are descriptive, rather than restrictive terms and expressions, which, when being used, are not inclined to rule out any equivalent of the already indicated and described features or component parts.

(38) Although several embodiments of this invention have been indicated and described, this invention shall not be limited to said described embodiments. On the contrary, the skilled artisan shall realize that any change or improvement can be made to these embodiments without deviating from the principles and essences of this invention. The protection scope of this invention is determined by the appended claims and equivalents thereof.