Method for producing a macroporous and mesoporous geopolymer, with controlled porosity

Abstract

The present invention relates to a method for preparing a macroporous and mesoporous geopolymer and especially a geopolymer foam, comprising the following successive steps (1) preparing a composite material comprising a geopolymer matrix and an organic liquid; then (2) eliminating said organic liquid by a treatment selected from the group consisting of heat treatment, oxidation treatment, photodegradation treatment and extraction using a supercritical fluid or ultrasounds.

Claims

1. A method for preparing a macroporous and mesoporous geopolymer comprising the successive steps consisting of: 1) preparing a composite material comprising a geopolymer matrix and an organic liquid; and then 2) removing said organic liquid by a treatment selected from the group consisting of at least one of a heat treatment, oxidation treatment, photodegradation treatment and an extraction via a supercritical fluid or ultrasounds, wherein said step (1) comprises the following sub-steps: a) preparing an activation solution comprising said organic liquid, b) adding to the solution obtained in step (a) at least one alumino-silicate source, c) subjecting the mixture obtained in step (b) to conditions allowing hardening of the geopolymer.

2. The method according to claim 1, wherein the composite material prepared during said step (1) appears as a geopolymer or a geopolymeric matrix in which beads of organic liquid and microbeads and/or nanobeads of organic liquid are coated.

3. The method according to claim 1, wherein said organic liquid comprises at most 50% of triglycerides by mass based on the total dry mass of said organic liquid.

4. The method according to claim 1, wherein said organic liquid is an unsaponifiable organic liquid.

5. The method according to claim 1, wherein said organic liquid comprises a thermally insulating oil.

6. The method according to claim 1, wherein said organic liquid comprises at least one element selected from the group consisting of a naphthenic oil; an aliphatic hydrocarbon; an unsaturated linear synthetic hydrocarbon; an aromatic hydrocarbon; a chlorinated linear hydrocarbon; a chlorinated aromatic hydrocarbon; a chlorinated-fluorinated linear hydrocarbon; an ethylenic aromatic hydrocarbon; a chlorinated solvent; an oxygenated solvent; an alkyl phosphate; an alkyl chloride and a liquid silicone.

7. The method according to claim 1, wherein said organic liquid comprises at least one element selected from the group consisting of commercial scintillator liquid, motor oil, oil for transformers, benzene, alkylbenzene, alkylnaphthalene, alkylbiphenyl, toluene, xylene, ethylbenzene, kerosene, hexane, cyclohexane, octane, ethylcyclohexane, dodecane, eicosane, phenol, dichloromethane, trichloroethane, dichlorobenzene, trichloroethylene, perchlorethylene, trichlorobenzene, polychlorobiphenyl, trichloro-trifluoroethane, alkyldiarylethylene, 2-octanone, 4-dodecanone, tributyl phosphate (TBP), tetrahydrofuran (THF), diethyl ether, polydimethylsiloxane and polydiphenylsiloxane.

8. The method according to claim 1, wherein surfactant(s) is(are) added () to said activation solution prior to the addition of said organic liquid, () to said organic liquid prior to its addition in said activation solution or () to said activation solution into which the organic liquid has already been added.

9. The method according to claim 1, wherein in addition to the alumino-silicate source, sand, granulate and/or fines are added to the activation solution during said sub-step (b).

10. The method according to claim 1, wherein said heat treatment consists of subjecting the composite material of step (1) to a temperature above 200 C.

11. The method according to claim 1, wherein said oxidation treatment is either a plasma treatment or an ozone treatment.

12. The method according to claim 1, wherein said supercritical fluid is selected from the group consisting of at least one of supercritical carbon dioxide (CO.sub.2), supercritical nitrogen monoxide (N.sub.2O), supercritical chlorodifluoromethane, supercritical trifluoromethane, supercritical methanol, supercritical hexane and supercritical water.

13. The method according to claim 3, wherein said organic liquid comprises at most 40% of triglycerides by mass based on the total dry mass of said organic liquid.

14. The method according to claim 3, wherein said organic liquid comprises at most 30% of triglycerides by mass based on the total dry mass of said organic liquid.

15. The method according to claim 3, wherein said organic liquid comprises at most 20% of triglycerides by mass based on the total dry mass of said organic liquid.

16. The method according to claim 3, wherein said organic liquid comprises at most 10% of triglycerides by mass based on the total dry mass of said organic liquid.

17. The method according to claim 1, wherein said organic liquid is a thermally insulating oil.

18. The method according to claim 1, wherein said organic liquid is at least one element selected from the group consisting of a naphthenic oil; an aliphatic hydrocarbon; an unsaturated linear synthetic hydrocarbon; an aromatic hydrocarbon; a chlorinated linear hydrocarbon; a chlorinated aromatic hydrocarbon; a chlorinated-fluorinated linear hydrocarbon; an ethylenic aromatic hydrocarbon; a chlorinated solvent; an oxygenated solvent; an alkyl phosphate; an alkyl chloride and a liquid silicone.

19. The method according to claim 1, wherein said organic liquid is at least one element selected from the group consisting of commercial scintillator liquid, motor oil, oil for transformers, benzene, alkylbenzene, alkylnaphthalene, alkylbiphenyl, toluene, xylene, ethylbenzene, kerosene, hexane, cyclohexane, octane, ethylcyclohexane, dodecane, eicosane, phenol, dichloromethane, trichloroethane, dichlorobenzene, trichloroethylene, perchlorethylene, trichlorobenzene, polychlorobiphenyl, trichloro-trifluoroethane, alkyldiarylethylene, 2-octanone, 4-dodecanone, tributyl phosphate (TBP), tetrahydrofuran (THF), diethyl ether, polydimethylsiloxane and polydiphenylsiloxane.

20. The method according to claim 10, wherein said heat treatment consists of subjecting the composite material of step (1) to a temperature between 300 C. and 1,000 C.

21. The method according to claim 10, wherein said heat treatment consists of subjecting the composite material of step (1) to a temperature between 400 C. and 800 C.

22. The method according to claim 1, wherein said organic liquid comprises at least one element selected from the group consisting of an aromatic synthetic hydrocarbon, an alcohol, a ketone, a glycol ether and an ether oxide.

23. The method according to claim 1, wherein said organic liquid is at least one element selected from the group consisting of an aromatic synthetic hydrocarbon, an alcohol, a ketone, a glycol ether and an ether oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a scanning electron microscopy view of a geopolymer foam with 20% of organic liquid according to the present invention.

(2) FIG. 2 is a scanning electron microscopy view of a geopolymer foam with 40% of organic liquid according to the present invention.

(3) FIG. 3 is a scanning electron microscopy view of a geopolymer foam with 50% of organic liquid according to the present invention.

(4) FIG. 4 shows the distribution of the pore sizes by mercury porosimetry of the geopolymer foam with 40% of organic liquid according to the present invention.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

(5) Geopolymer foams according to the present invention were prepared from the geopolymer+organic liquid (oil) composite with 20, 40 and 50% by volume of organic liquid.

(6) The products used for the geopolymer are metakaolin from Pieri Premix MK (Grade Construction Products), NaOH (Prolabo, 98%), sodium silicate Betol 52T (Woellner) and motor oil as an organic liquid (or matrix or template). The compositions are copied into the table hereafter.

(7) TABLE-US-00001 TABLE 1 Composition of the mortar for microencapsulation of oil Template % (Vol.) Binder composition (in g) 20 NaOH: 38.3 H.sub.2O: 113.6 Betol 52 T: 393 Metakaolin: 374.7 Oil: 87.7 40 NaOH: 34.5 H.sub.2O: 102.2 Betol 52 T: 353.7 Metakaolin: 377.3 Oil: 210.5 50 NaOH: 4.8 H.sub.2O: 14.2 Betol 52 T: 49.1 Metakaolin: 46.8 Oil: 43.3

(8) After setting, the geopolymer+organic liquid (oil) composites are put into an oven at 400 C., for 2 h, in air, in order to release the porosity of the composite.

(9) In FIGS. 1, 2 and 3, are copied the SEM photographs of geopolymer foams after heat treatment at 400 C., a porous network clearly appears increasingly dense with increase in the load of template in the geopolymer. The macropores have a size of the order of 10 m.

(10) A distribution of the pore sizes by mercury porosimetry was achieved on the geopolymer foam with 40% of organic matrix, and a double macroporosity appears located between 1-10 m and 0.1 m (FIG. 4).

REFERENCES

(11) [1] Calmon, 1980, Explosion hazards of using nitric acid in ion-exchange equipment, Chemical Engineering, Vol. 87, pages 271-274. [2] Pillay, 1986, A review of the radiation stability of ion exchange materials, Journal of Radioanalytical and Nuclear Chemistry, Vol. 102, pages 247-268. [3] Prud'homme et al, 2011, In situ inorganic foams prepared from various clays at low temperature, Applied Clay Science, Vol. 51, pages 15-22. [4] Medri et al, 2013, Effect of metallic Si addition on polymerization degree of in situ foamed alkali-aluminosilicates, Ceramics International, Vol. 39, pages 7657-7668. [5] Rickard and Van Riessen, 2013, Performance of solid and cellular structured fly ash geopolymers exposed to a simulated fire, Cement and Concrete Composites. [6] Strozi Cilla et al, 2014, Geopolymerfoams by gelcasting, Ceramics International, Vol. 40, pages 5723-5730.