ORGANOMETALLIC COORDINATION POLYMER FOR ACCUMULATION OF NATURAL GAS, METHANE AND THE METHOD FOR PRODUCTION THEREOF

Abstract

The invention relates to a method for production of an organometallic coordination polymer and to a material obtained using the method provided. Synthesized according to the method, this organometallic coordination polymer has gel structure and is characterized by availability of nanopores with the effective diameter of 0.75-0.80 nm, specific area of 1300 to 1700 m.sup.2/g, micropore volume of 0.5-0.6 cm.sup.3/g, and increased thermal stability. The method of synthesis allows for reduction of material consumption during the process by using a single solvent at the synthesis and activation stages, for reduction of time for the production of polymer gel that is characterized by availability of active meso and micropores which will make it possible to use it as a base in various absorption processes including natural gas storage systems.

Claims

1. Method for production of organometallic coordination polymer for accumulation of natural gas, methane, comprising the stage of synthesis that consists of interaction of equimolar amounts of the crystalline hydrate of aluminum nitrate and trimesic acid dissolved in an aprotonic polar organic solvent with boiling temperature over 80? C., taken in equimolar or excessive amount related to reagents; wherein the solution of the aluminum nitrate crystalline hydrate is heated up to 110? C., the solution of trimesic acid is heated up to 80-110? C., and the heated trimesic acid solution is added dropwise to the heated aluminum nitrate solution with intensive stirring at the rate of 5-15 vol. % per minute, and the solution mix is heated up to 140? C., held until sol is generated, and the latter is polymerized at 100-150? C. for 2-3 days until organometallic coordination polymer with gel structure is obtained; and the activation stage consisting of multiple washing of the synthesized organometallic coordination polymer with gel structure with an aprotonic polar organic solvent used at the synthesis stage and heated up to 40-60? C. in vacuum at pressure drop of at least 90 kPa, drying up to 24 hours under normal conditions at first, and then at 100-150? C., thermal vacuum treatment up to 6 hours at the temperature of 120-300? C. and residual pressure of 0.26 kPa; the activation stage is terminated upon stabilization of the weight of organometallic coordination polymer with the gel structure.

2. Organometallic coordination polymer with the gel structure for accumulation of natural gas, methane, that is thermally stable at temperatures of at least 500? C. and has pores with effective inner diameter of 0.75-0.80 nm, specific area of 1300 to 1700 m.sup.2/g, micropore volume of 0.5-0.6 cm.sup.3/g, and total micropore volume of 1.0-1.8 cm.sup.3/g.

Description

[0019] The group of inventions is explained in Tables and Figures:

[0020] Table 1Chemical Composition of the Organometallic Gel Synthesized, where: Wtweight percent, Atatom percent;

[0021] Table 2Parameters of the Porous Structure of the Organometallic Gel Specimens Synthesized, where: V.sub.0specific micropore volume, cm.sup.3/g; E.sub.0nitrogen adsorption characteristic energy, kJ/mol; Dmicropore effective inner diameter, nm; Ebenzene adsorption characteristic energy, kJ/mol; S.sub.BETspecific surface area as per BET method, m.sup.2/g; V.sub.ssummarized pore volume, cm.sup.3/g; S.sub.memesopore area, m.sup.2/g; V.sub.memesopore volume, cm.sup.3/g.

[0022] FIG. 1electronic scanning microscopy photograph of the specimen of organometallic coordination polymer with gel structure obtained;

[0023] FIG. 2IR specters of the synthesized organometallic coordination polymer with gel structuresolid line; organometallic polymer based on aluminum (prototype)dashed line.

[0024] FIG. 3diffraction patterns of the synthesized organometallic coordination polymer with gel structuretop line; organometallic polymer based on aluminum (prototype)bottom line.

[0025] FIG. 4thermograms: solid linesynthesized specimen of organometallic coordination polymer with gel structure; dashed lineorganometallic polymer with gel structure based on aluminum (prototype).

[0026] FIG. 5isothermal curve of nitrogen adsorption/desorption at 77 K on the specimen (1). Light symbolsadsorption. Dark symbolsdesorption.

[0027] FIG. 6framework model of the fragment of the synthesized organometallic coordination polymer where D is the micropore effective inner diameter.

[0028] The group of inventions proposed is implemented as follows.

Example 1

[0029] Trimesic acid (1,3,5-benzen tricarboxylic acid (H.sub.3BTC)) and aluminum nitrate crystalline hydrate Al(NO.sub.3).sub.3.Math.9H.sub.2O were dissolved in the organic solvent N,N-dimethyl formamide with molar ratio of 1:1 (1 mol of acid per 1 mol of solvent, and 1 mol of salt per 1 mol of solvent). Obtained solutions were heated up (up to 110? C. for aluminum salt solution and up to 80? C. for trimesic acid solution). Then, heated up solution of trimesic acid was added dropwise to the aluminum salt solution at the rate of 5-15 vol. %/min, with intensive stirring using a magnetic stir bar and gradual increase in the reaction mix temperature up to 140? C., and it was held until sol would be formed (solution thickening). Obtained sol was placed in an assay autoclave with a tight screwed cover and fluoroplastic liner after which it was placed in a furnace where synthesis at 100? C. was carried out, with gradual heating up to 140?, and it was held for two days. Activation was carried out as follows: organometallic gel (OMG) residue that formed was separated from the mother liquor by thermal vacuum filtration (desorption of solvent molecules), in particular, by multiple washing with solvent (150 ml N,N-dimethyl formamide heated up to 60? C.) under vacuum conditions, at pressure drop of at least 90 kPa. Then, the residue was dried first under standard conditions, and then in a drying furnace at 100? C., with increase up to 140? C. during 20 h, and it was held at 140? C. for 4 more hours. Under such drying conditions, surface moisture is removed first (at 100? C.), and then the interstitial unbound moisture (100-140? C.) is removed which allows for stabilizing the synthesized OMG framework. OMG specimen obtained was activated for maximum removal of interstitial bound (crystalline hydrate) moisture and solvent in a thermal vacuum chamber at the temperature of 200? C. and residual pressure of 0.26 kPa (2 mm Hg) until constant weight is obtained (approximately 6 hours).

[0030] The specimen obtained is an organometallic coordination polymer (OMCP) on the basis of aluminum ions coordinated with ligands of trimesic acid, and it has gel structure and the surface chemical composition specified in Table 1. Its physical and chemical properties are confirmed by the assay results illustrated in: FIG. 2IR specter absorption characteristic of the material; FIG. 3diffraction pattern; FIG. 4thermogram; FIG. 5adsorption isothermal curves. Electronic scanning microscopy photograph of the obtained OMCP specimen with gel structure (FIG. 1) shows availability of crystals of different size and a small amount of amorphous phase between them which demonstrates inhomogeneity of the molar mass distribution of the polymer obtained due to reduction of the time for synthesis thereof in comparison with the prototype. Selection of special activation conditions for maximum removal of both free and bound liquid phase facilitates pore structure keeping and provides for acceptable strength and thermal stability of the OMCP (FIG. 4). Under high aerodynamic load that a natural gas accumulator is affected by during operation, such characteristics are preferable, and this explains the advantages of the polymer gel structure obtained for specific intended use in comparison with the OMCP structures with high degree of crystallinity which are solid, but brittle.

[0031] IR specter absorption bands of the synthesized OMCP, FIG. 2, observed within the interval of 663-766 cm.sup.?1 correspond with the bond vibrations in the benzene nucleus and outside the aromatic ring plane. Bands occurring between 827-1153 cm.sup.?1 relate to symmetric and asymmetric deformation vibrations OC?O. Intensive absorption peaks at 1368, 1445 and 1640 cm.sup.?1 are connected with deformation vibrations of CO bonds, asymmetric and symmetric types of C?O respectively withinCOOH group (in trimesic acid). Such characteristics also show that the OMCP has formed the chemical composition claimed.

[0032] Results of thermal stability assay for the synthesized OMCP with gel structure illustrated in FIG. 4 made it possible to determine that its thermal decomposition occurs at temperatures over 500? C. This is the evidence of elevated thermal stability of the polymer obtained in comparison with known organometallic coordination polymers on the basis of aluminum cations coordinated with trimesic acid ligands.

[0033] Analysis of the parameters of the synthesized specimen (1) porous structure (see Table 2) of the organometallic gel according to the isothermal curve of the standard nitrogen vapor at the temperature of minus 196.15? C. (77 K), FIG. 5, was carried out by BET method and the theory of volume filling of micropores. Adsorption isothermal curve form is characteristic of micro-mesoporous adsorbents. FIGS. 6 and 7 illustrate framework models of organometallic gel (OMG) fragments that schematically show its geometry and porous characteristics.

Example 2

[0034] It differs from Example 1 in the fact that the trimesic acid solution was heated up to 110? C., and then it was added to the solution of the aluminum nitrate crystalline hydrate during stirring at the rate of 1 ml/min. Synthesis stage was carried out with temperature increase from 100 to 120? C., and then it was held at 120? C. for 60 more hours. Drying stage in the drying furnace was carried out at the temperature of 100? C., with gradual heating up to 120? C. It was held in the thermal vacuum chamber at 120?. Porous structure assay results for the obtained specimen of organometallic gel (2) are given in Table 2.

Example 3

[0035] It differs from Example 1 in the fact that trimesic acid and aluminum nitrate crystalline hydrate were dissolved in the organic solvent diethyl sulfoxide with molar ratio of 1:2 (1 mol of acid per 2 mol of solvent, and 1 mol of salt per 2 mol of solvent). Synthesis stage was carried out with temperature increase from 100 to 150? C., and then it was held at 150? C. for 48 more hours. Drying stage in the drying furnace was carried out at the temperature of 100? C., with gradual heating up to 130? C. It was held in the thermal vacuum chamber at 250? C. Porous structure assay results for the obtained specimen of organometallic gel (3) are given in Table 2.

Example 4

[0036] It differs from Example 1 in the fact that diethyl formamide was used as a solvent, and the synthesis stage was carried out at the temperature of 120? C. during 60 h. Drying stage in the drying furnace was carried out at the temperature of 100? C., with gradual heating up to 120? C. It was held in the thermal vacuum chamber at 300?. Porous structure assay results for the obtained specimen of organometallic gel (4) are given in Table 2.

Example 5

[0037] It differs from Example 1 in the fact that the synthesis stage was carried out at the temperature of 130? C., with temperature increase up to 140? C., and then it was held at the temperature of 140? C. for 48 more hours; and the activation stage was carried out by the method of filtering with a solvent, dimethyl sulfoxide, heated up to the temperature of 40? C., and drying in the drying furnace was carried out at 100? C. with heating up to 140? C., and it was held in the thermal vacuum chamber at 160? C. Porous structure assay results for the obtained specimen of organometallic gel (5) are given in Table 2.

[0038] The group of inventions provided allows for production of an organometallic coordination polymer with gel structure, with developed inner surface consisting of micro and mesopores that, in comparison with similar materials, has higher thermal stability, and drying and activation parameters of which facilitate the maximum maintenance of porous characteristics obtained at the stage of synthesis which in general is the evidence that the technical result claimed is achieved.

TABLE-US-00001 TABLE 1 Element Wt, % At, % CarbonC 46.16 55.37 OxygenO 43.35 39.03 AluminumAl 10.49 5.60

TABLE-US-00002 TABLE 2 V.sub.0, E.sub.0, D, E, S.sub.BET, V.sub.s, S.sub.me, V.sub.me, OMG cm.sup.3/g kJ/mol nm kJ/mol m.sup.2/g cm.sup.3/g m.sup.2/g c.sup.m/g (1) 0.60 15.4 0.79 5.1 1700 1.8 430 1.20 (2) 0.50 15.0 0.80 5.0 1300 1.0 328 0.53 (3) 0.57 15.3 0.78 5.1 1560 1.1 350 0.56 (4) 0.51 15.1 0.80 5.0 1410 1.4 400 0.86 (5) 0.53 15.9 0.75 5.2 1530 1.7 439 1.22