KR101067448B1 - Superprotonic hybrid membrane from zirconium phosphate solid acid and proton-beta-alumina and the preparation method thereof - Google Patents

Abstract

The present invention is a K ⁺ -β "-alumina as a precursor to the acetic acid and ammonium of _{^{H 3 O + / NH 4 +}} -β nitrate by ion exchange one seconds ion conductor (super ionic conductor)" -alumina been sintered to a support And penetrating zirconium phosphate, which is a conductive solid acid, to prepare a superproton conductive hybrid membrane.

Description

Superprotonic hybrid membrane from zirconium phosphate solid acid and proton-beta-alumina and the preparation method according to zirconium phosphate solid acid and proton-beta-alumina

The present invention relates to a method for producing a super-proton electroconductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina, and more particularly, to solve a problem due to the operating temperature at 80 ° C of PEMFCs (proton exchange membrane fuel cell). Using zirconium phosphate solid acid and proton-beta-alumina supported on solid acid used in mesophilic fuel cell and proton-β "-alumina, a super ion conductor with high ion conductivity near 300 ℃ It relates to a method for producing a superproton conductive hybrid membrane.

Recently, fuel cell technology has been put to practical use due to the large technological development of PEMFC using perfluorosulfonic acid (PFSA) polymer membrane (eg, Nafion) as an electrolyte. PEMFC is one of the most promising clean energy technologies. It has the advantage of being more than 64% efficient and having high energy density compared to primary and secondary batteries, and can be manufactured in thin film. However, despite these advantages, PEMFC, which is currently in use, uses a weak Nafion membrane at a high temperature, and thus has a number of major problems with a low temperature fuel cell having an operating temperature of about 80 ° C.

  The proton conductivity across the membrane is directly proportional to the degree of hydration of the membrane. Therefore, the fuel to be supplied must be humidified enough to not dry the membrane. Therefore, the moisture (humidity) and temperature control of the system must be managed very carefully, which is a sensitive and not easy problem. In addition, PEMFCs operating at low temperatures poison the Pt catalyst of the anode with trace amounts of CO.

 These problems can be greatly improved by raising the operating temperature of the PEMFC above 100 ° C. The allowance of CO to prevent poisoning of the Pt catalyst of the anode is rapidly increased to 20 ppm at 80 ° C, 1,000 ppm at 130 ° C and 30,000 ppm at 200 ° C.

  On the other hand, in the case of moisture (humidity) and temperature management, the temperature inside the cell above the boiling point of the water is only present as a single phase of water vapor as the operating temperature rises, thereby simplifying the control and management of the system. In addition, the increased operating temperature of the PEMFC brings several other advantages. In other words, the reaction rate can be increased to reduce the use of noble metal catalysts, and the resistance of the membrane is lowered by increasing the movement speed of protons.

In addition, current PEMFCs operate at low temperatures of 80 ° C, resulting in very little heat recovery. However, if the internal pressure is increased by about 15 atm at the operating temperature of about 200 ℃, the amount of heat that can be recovered is greatly increased, which can be directly used for heating the system and supplying steam, thereby improving the overall efficiency of the fuel cell. In addition, the operating temperature of about 200 ℃ is close to the temperature for the reforming of methanol and the desorption of hydrogen from hydrogen storage materials (e.g., NaAlH ₄ ), which is recently attracting attention. Therefore, it is possible to develop a technology that can replace the expensive fuel hydrogen.

As mentioned above, when constructing a high temperature cell by increasing the operating temperature of PEMFC close to 200 ℃, fuel cell efficiency is increased, weight is reduced, volume is reduced, configuration is simplified, operation is simple, configuration and operation cost are reduced. There is a lot of interest and research in this field.

On the other hand, SAFCs (solid acid fuel cell) has a number of advantages compared to the conventional fuel cells, such as PEMFCs because it is operated at a medium temperature of 150 ℃ to 300 ℃.

In general, the electrode reaction rate increases as the temperature increases. Therefore, the reaction energy, which is difficult to proceed in the vicinity of room temperature, may be easily progressed when the reaction temperature becomes high. In the low temperature region below 200 ℃, electrode reactions that do not proceed smoothly without expensive precious metal catalysts such as Pt and Ru are more likely to occur when the reaction source system exceeds the acid of activation energy at a high temperature of 100 ℃. It proceeds quickly.

In the case of fuel cell electrodes, this means that the higher the temperature, the smaller the potential change, even if the current is drawn, that is, the smaller the polarization. Therefore, it is unnecessary to add an expensive noble metal catalyst, which is indispensable in a low temperature fuel cell of 200 ° C. or lower, to be replaced with an inexpensive catalyst. In this state, since high power density can be generated, high power generation efficiency can be expected as compared with low temperature type. In addition, when the temperature rises, the electrode reaction proceeds smoothly, and various types of fuels can be used.

Another feature of high temperature fuel cells is the ease of use of heat dissipation by high temperature operation. In general, the higher the temperature of the heat source, the higher the utilization of thermal energy. For example, the heat dissipation of a polymer solid electrolyte membrane fuel cell should be high at about 80 ° C., but this temperature can only be used for heating. On the other hand, high-temperature fuel cells can utilize high-quality heat dissipation up to several hundred degrees Celsius in addition to the electrical energy obtained by power generation. In this case, the heat is generated again by heat generation by turbine generator or Seebeck effect by the release of this heat, and then it can be used as a heat source for cooling or heating. Therefore, the total ratio of the conversion power to the thermal energy used, that is, the total fuel cell efficiency, is much higher than that of the low temperature fuel cell.

However, problems have arisen due to the operating temperatures of PEMFCs in use at 80 ° C and due to their low ionic conductivity at high temperatures, zirconium phosphate solid acid, a solid acid used in SAFCs, Membrane) has been a lot of constraints.

In addition, the production of proton-beta-aluminas by ion exchange from Na ⁺ -beta-alumina is very difficult due to the large difference in ion radius, which can break the crystal structure due to large stress during ion exchange. There was a problem that only ion exchange completely.

Therefore, it is necessary to develop a composite membrane using zirconium phosphate and proton-beta-aluminas, which are conductive solid acids, to solve the above problems.

An object of the present invention is to prepare a composite membrane using zirconium phosphate, which is a conductive solid acid, as a support using H ₃ O ⁺ / NH ₄ ⁺ -β ″ -alumina, which is a super ionic conductor.

The present invention is H ₃ O ⁺ / NH ₄ ⁺ -β ″ -alumina, a super ionic conductor ion-exchanged with acetic acid and ammonium nitrate using K ⁺ -β "-alumina sintered at 1400 ℃ as a precursor It is characterized in that it is prepared by infiltrating zirconium phosphate which is a conductive solid acid as a support.

The zirconium phosphate is prepared by adding H ₃ PO ₄ to a water-containing ZrOCl ₂ 8H ₂ O solution, washing and drying at 368 K.

The zirconium phosphate is prepared by dissociating ZrOCl ₂ 8H ₂ O in 2M HCl, mixing dilute H ₃ PO ₄ at 1000 rpm, filtering, washing with H ₃ PO ₄ , drying at 368 K, and then processing. .

The zirconium phosphate is adjusted by dissolving the surfactant Aniline and span-tween in ethanol, adding HCl to PH = 2 or less, mixing zirconium ions, adding phosphoric acid, aging the mixture, filtering and washing with ethanol And dried to 120 ° C.

The zirconium phosphate is dissolved in ZrOCl ₂ 8H ₂ O in distilled water and then added (NH ₄ ) ₂ CO ₃ and (NH ₄ ) ₂ HPO ₄ to the solution, and then stored in an oven at a temperature of 80 ℃, 90 ℃ Aged at 120 ° C., cooled, filtered, washed, dried, and calcined at 540 ° C.

The zirconium phosphate is prepared by dissolving ZrOCl ₂ 8H ₂ O in water, adding H ₃ PO ₄ and hydrofluoric acid, and then aging at 80 ° C.

According to the present invention, by combining with the existing PEM fuel cell that has been put into practical use to develop a medium temperature PEM fuel cell, it is possible to improve the performance and efficiency of the battery, and to replace the polymer membrane, a great economic benefit in the material and energy business field Can create.

In addition, according to the present invention, when a medium temperature type PEM fuel cell is developed, not only can be utilized as a power generation system to maximize energy efficiency and improve performance, but also can be utilized as a power supply device of an electric vehicle or a hybrid vehicle to improve energy efficiency. In addition, it can improve the economics by supplying medium temperature PEM fuel cell to home small power generation device.

In addition, according to the present invention, the PEM fuel cell can be expected to operate at a medium temperature of about 200 ℃ and the following advantages. That is, (1) reducing the use of noble metal catalysts (Pt, etc.) by increasing the reaction rate, (2) mitigating the poisoning of CO generated in the anode, and (3) increasing the migration rate of the protons. It increases efficiency with decreasing resistance, (4) simplifies the control and management of water and temperature management system of PEM, and (5) improves current density and output of battery and improves energy efficiency to improve economic efficiency.

In addition, according to the present invention, since the conventional PEMFC operates at a low temperature of 80 ° C., the recovery of thermal energy is very insignificant. However, if the internal pressure is increased by about 15 atm at an operating temperature of about 200 ° C., the amount of heat that can be recovered is greatly increased. It can be used directly for heating and supplying steam to increase the overall efficiency of the fuel cell, and operating temperature of about 200 ℃ can desorb hydrogen from reforming methanol and hydrogen storage materials which are recently attracting attention. It is possible to develop a technology that can replace hydrogen, which is an expensive fuel, near the temperature that can be achieved.

In addition, according to the present invention, when constructing a medium temperature cell by increasing the operating temperature of the PEMFC close to 200 ° C, the current density, output and efficiency of the fuel cell, increase in weight, decrease in volume (size), configuration of Simplification, simplicity of operation, and reduced configuration and operating costs can be expected.

1 is a schematic view showing a PEMFC using a perfluorosulfonic acid (PFSA) polymer membrane (eg, Nafion) as an electrolyte according to the related art.
Figure 2a is a solid state reaction schematic, Figure 2b is a calcination schedule.
3 is a diagram illustrating a sintering schedule.
4 shows the XRD pattern of K + -β "-alumina specimens.
Figure 5 (a) is the ion exchange rate using 10 wt.% Acetic acid according to three reaction times at 150 ℃, (b) is the ion exchange rate using 50 wt.% Acetic acid at 150 ℃, ( c) is a graph showing the ion exchange rate using 10 wt.% acetic acid according to three reaction times at 170 ℃.
FIG. 6 is a diagram showing an XRD pattern of ion exchange using 10 wt.% Acetic acid at 150 ° C. FIG.
FIG. 7 is a diagram showing an XRD pattern of ion exchange using 50 wt.% Acetic acid at 150 ° C. FIG.
8 is a diagram showing an XRD pattern of ion exchange using 10 wt.% Acetic acid at 170 ° C.
9 is (A) ion exchange rate when using 5 M ammonium nitrate at 170 ℃, (B) ion exchange rate using 10 M ammonium nitrate at 100 ℃, (C) 10 M ammonium nitrate at 130 ℃ The ion exchange rate used.
10 shows (A) ion exchange rate using 10 M ammonium nitrate at 150 ° C., (B) ion exchange rate using 10 M ammonium nitrate at 170 ° C., and (C) ion using 10 M ammonium nitrate at 200 ° C. Exchange rate, and (D) ion exchange rate using molten ammonium nitrate at 200 ° C.
Fig. 11 shows (A) XRD patterns of ion exchange using 5 M ammonium nitrate at 170 ° C, and (B) XRD patterns of ion exchange using 10 M ammonium nitrate at 100 ° C.
Figure 12 (A) is an XRD pattern of ion exchange using 10 M ammonium nitrate at 130 ° C, and (B) is an XRD pattern of ion exchange using 10 M ammonium nitrate at 150 ° C.
Fig. 13 shows (A) XRD patterns of ion exchange using 10 M ammonium nitrate at 170 ° C, and (B) XRD patterns of ion exchange using 10 M ammonium nitrate at 200 ° C.
Figure 14 (A) XRD pattern of ion exchange using molten ammonium nitrate at 200 ° C.
15 is an XRD pattern of ion exchange for 4 hours using water at 170 ° C.
Fig. 16 shows the relative density of sintered K ⁺ -β "-aluminas.
Figure 17 (A) SEM image of K ⁺ -β "-alumina sintered at 1400 ° C (x5,000), (B) SEM image of K ⁺ -β" -alumina sintered at 1400 ° C (x10,000) )to be.
FIG. 18A is a view showing the step of synthesizing by adding H ₃ PO ₄ to the ZrOCl ₂ 8H ₂ O solution, FIG. 18B is the TGA / DTA measurement result of FIG. 18A, and FIG. 18C is an SEM measurement (x2,000). 18D shows the SEM measurement (x5,000), FIGS. 18E and F show the EDS measurement, and FIG. 18G shows the XRD measurement.
FIG. 19a is a view showing the step of dissociating ZrOCl ₂ 8H ₂ O into 2M HCl and adding dilute H ₃ PO ₄ , FIG. 19b is the TGA / DTA measurement result of FIG. 19a, and FIG. 19c is the SEM measurement result. (x2,000), Fig. 19D is the SEM measurement result (x5,000), Figs. 19E and F are the EDS measurement results, and Fig. 19G is the XRD measurement results.
FIG. 20a is a diagram illustrating a step of synthesizing ZrP using a surfactant Aniline and span-tween, FIG. 20b is a TGA / DTA measurement result of Anilin, FIG. 20c is a TGA / DTA measurement result of span-tween, and FIG. 20d Is the SEM measurement result of Anilin (x5,000), Figure 20e is the SEM measurement result of Anilin (x20,000), Figure 20f is the SEM measurement result of the span-tween (x5,000), Figure 20g is span- SEM measurement result of tween (x10,000), Figure 20h, i is the result of Eni measurement of Anilin, Figure 20j, k is the result of EDS measurement of span-tween, Figure 20l is the XRD measurement result of Anilin, Figure 20m Is the result of XRD measurement of span-tween.
FIG. 21A shows a step of synthesizing a spherical ZrP using the sol-gel method, FIG. 21B is a TGA / DTA measurement result of FIG. 21A, FIG. 21C is an SEM measurement result (x3,000), and FIG. 20D is an SEM Measurement results (x5,000), Figs. 21E and F are the EDS measurement results, and Fig. 21G is the XRD measurement results.
FIG. 22A is a diagram illustrating a step of synthesizing ZrP in a plate form by adding H ₃ PO ₄ and HF to ZrOCl ₂ 8H ₂ O, FIG. 22B is a TGA / DTA measurement result of FIG. 22A, and FIG. 22C is an SEM measurement result (x5). (000), Fig. 22D is the SEM measurement result (x10,000), Figs. 22E and F are the EDS measurement results, and Fig. 22G is the XRD measurement results.

Hereinafter, the features of the present invention and the features of each manufacturing step will be described in detail with reference to the following examples.

A super-proton conductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina operable at medium temperature according to the present invention was prepared to evaluate the electrical properties, phase stability, and mechanical properties.

In addition, the results of experiments and analyzes of zirconium phosphate as a solid acid, K ⁺ -β "-aluminas prepared using β ″ -alumina, and the resulting superproton conductive hybrid membranes will be described in order.

H ₃ O where the structural change occurs at about 400 ° C. because sintering is required at a high temperature of 1600 to 1700 ° C. in order to prepare the beta-aluminas of the dense structure and the electrical properties necessary to prepare the K ⁺ -β "-aluminas. It is impossible to sinter ⁺ / NH ₄ ⁺ -β "-alumina membranes.

Here, H ₃ O ⁺ / NH ₄ ⁺ -β ″ -alumina, which is intended to be used as a support, is a proton (H ⁺ , proton) conductor and has a single crystal ion conductivity of 3 x 10 ^-2 S / cm, 150 ℃ at 227 ℃. At 1.0 × 10 ⁻² S / cm, and at 5.3 ° C. at 5.3 × 10 ⁻³ S / cm.

Β ″ -alumina has a solid spinel block in which Al ³⁺ ions and O ² ions are present in the crystal structure, and there is a conductive surface with sufficient space between them, so that the charge carriers are placed on the conductive surface. As a representative material, Na ⁺ -beta-alumina is an excellent ceramic super ion conductor of Na ⁺ ion at 250 ~ 300 ℃.

In addition, the alkali ion, a charge carrier of beta-aluminas, can be replaced with other ions and can be converted into ceramic electrolyte with various electrical properties and functions.

In other words, through the above-mentioned facts to solve the problem that it is impossible to sinter H ₃ O ⁺ / NH ₄ ⁺ -β ''-alumina membrane at high temperature of 1600 ~ 1700 ℃ for the production of beta-aluminas of excellent electrical properties and dense structure The porous support was prepared by sintering K ⁺ -β "-alumina as a precursor material at 1400 ° C and performing ion exchange.

That is, the ion radius of K ⁺ ion is 0.133 nm, which is very similar to 0.13 nm or less, which is the ion radius of H ₃ O ⁺ / NH ₄ ⁺ ion used as proton carrier, and thus, H ₃ O ⁺ / NH ₄ ⁺ β ″ -alumina supports can be prepared.

K ⁺ Ion Exchange of -β "-alumina Sintered Body

Hereinafter, the raw materials and composition for the ion exchange experiment of the K ⁺ -β "-alumina sintered compact, a synthesis | combination, and a grinding | pulverization are demonstrated in order.

≪ Example 1 >

K ⁺ -β used in this experiment was prepared by calcining a -alumina "-aluminas pure K ⁺ -β via the _{K 2 O · Li 2 O ·} Al 2 O 3 solid-phase reaction method from a ternary" in 1200 ℃.

As an initial raw material, alumina was used as γ-Al ₂ O ₃ (99.9%), and K ₂ CO ₃ was used as a raw material for K ₂ O. As the raw material of the Li ₂ O also written as a stabilizer was used as the Li ₂ CO _3, was used as the ^{_{NH 4 + / H 3 O +}} -β " the ion exchange medium for the production of acetic acid glacial -alumina and ammonium nitrate.

As shown in FIGS. 2a and 2b, the synthesis of K ⁺ -β "-aluminas was carried out at a molar ratio of [K ₂ O]: [Al ₂ O ₃ ] = 1: 5, and 0.2 wt.% Of Li ₂ O was added as a stabilizer. It was.

In order to grind the mixed powder into a uniform size, alumina balls having a diameter of 25 mm, 20 mm, and 5 mm were placed in a jar having an internal diameter of 130 mm and ball milling was performed for 5 hours.

Rotational speed was maintained at 70 rpm during ball milling, and dried for 1 day in a 100 ° C convection oven to remove methanol used as a solvent after ball milling.

The dried mixed powder was placed in a high-temperature MgO crucible for high phase synthesis and maintained at 800 ° C. for 2 hours for reaction of the mixture, and then calcined at 1200 ° C. for 2 hours to synthesize a phase.

The synthesized K ⁺ -β "-aluminas was subjected to secondary grinding to make fine powder. Secondary grinding was performed by putting zirconia balls having a diameter of 1 mm into jars having an inner diameter of 105 mm and performing attrition milling.

Rotational speed was maintained at 330 rpm during attrition milling for 2 hours. After attrition milling it was dried for 1 day in a convection oven at 100 ℃.

The dried powder was ground evenly using mortar and pestle to remove aggregates.

The nano-sized K ⁺ -beta-aluminas powders dried after ultra-fine grinding for sintering were sufficiently removed from the aggregates with a caustic rod, and then weighed to 0.2 g using a disc hardened steel mold having an inner diameter of 14.2 mm. The uniaxial press for 3 minutes at the pressure of. Molded specimens were prepared in pellet-shaped specimens approximately 14.2 mm in diameter.

In order to minimize the friction between the mold and the specimen during the fabrication, olive oil, a lubricant, was sufficiently applied to the inside of the mold, and a small amount of powder on the mold wall was completely removed and molded.

As shown in Figure 3, the sintering of K ⁺ -β "-aluminas is sintered by varying the sintering temperature to 1300 ℃, 1400 ℃, 1500 ℃ in order to produce a solid acid can penetrate large amounts to function as a support It was.

In addition, considering the phase transition characteristics at high temperatures of K ⁺ -β "-aluminas and the vapor pressure of K ₂ O, each specimen was filled with an alumina crucible and sealed using a powder of the same composition as an atmosphere powder, followed by sintering in a high temperature electric furnace. It was.

On the other hand, acetic acid and ammonium nitrate were used as ion exchange media for ion exchange with H ₃ O ⁺ / NH ₄ ⁺ -β "-alumina of sintered K ⁺ -β" -alumina. Phase stability and degree of ion exchange were analyzed by varying the temperature, time, and concentration in the ion exchange process.

Ion exchange was carried out by hydrothermal reaction in a 15 ml teflon-lined clave for acetic acid. In order to investigate the phase stability and ion exchange degree with respect to temperature and time, ion exchange was carried out at 150 ° C, 170 ° C, and 200 ° C for 2 hours to 8 hours at intervals of 2 hours, and the molar ratio of potassium and acetic acid, an ion medium Ion exchange was performed by setting [K ₂ O]: [CH ₃ COOH] = 1:50. In addition, the ion exchange was carried out by changing to 10 wt.%, 50 wt.% To determine the effect on the concentration.

Ammonium nitrate was subjected to hydrothermal reaction at 130 ℃, 150 ℃, 170 ℃ and 200 ℃ for 2 hours at 2 hours to 8 hours by hydrothermal reaction in 15 ml of teflon-lined clave in the same way as acetic acid. Ion exchange was carried out with the molar ratio of ammonium nitrate to [K ₂ O]: [NH ₄ NO ₃ ] = 1:50. The concentration was changed to 5 M and 10 M and ion exchange was performed.

In addition, the ammonium nitrate salt was dissolved at 200 ° C. and ion exchanged for 2 to 8 hours at 2 hour intervals.

In addition, in order to examine the effect of the number of repetition of ion exchange, both media were repeatedly subjected to ion exchange from 1 to 3 times. After the ion exchange, the sintered body was washed with ultrapure water and soaked in ultrapure water for 1 day. The washed sintered body was dried in a convection oven for 1 day.

Experimental Example 1 Measurement of Ion Exchange Degree

In order to measure the degree of ion exchange of K ⁺ -β-alumina sintered body to proton (H ₃ O ⁺ / NH ₄ ⁺ ) -β ″ -alumina, the residual amount of potassium was measured by ICP-AES (spectro, Modular EOP). The exchange rate was confirmed. Equation 1 was used to calculate the ion exchange rate.

To prepare a sample for ICP-AES measurement, 0.1 g of sample was added to 10 ml of a solution prepared by mixing 98 wt.% Concentrated sulfuric acid and distilled water in a 1: 2 solution, which was placed in a 15 ml pressurized container at about 180 ° C. The powder was dissolved by heating for 18 h. The samples that were not completely dissolved after the reaction were completely dissolved in concentrated sulfuric acid and then diluted 50-fold with ultrapure water to dilute the ICP-AES measurement range. In order to reduce the error of each sample was measured three times the average value.

Experimental Example 2 X-ray Diffraction Analysis

K ⁺ -β "-alumina sintered bodies were ion exchanged with acetic acid and ammonium nitrate in ion exchange media, and X-ray diffraction analysis was performed to investigate the phase change before and after. X-ray diffractometer (Rigaku Rint 2000, Japan) was measured using Cu Kα-radiation with a step width of 0.04 and scan speed of 10 ㅀ / min from 5 ㅀ to 75 인 in the range of 2 θ with an output of 40 ㎸ and 30 ㎃. .

Experimental Example 3 Measurement of Density of Sintered Body

The density of the ion- exchanged proton (H ₃ O ⁺ / NH ₄ ⁺ ) -β "-alumina sintered body was measured to determine whether it has enough pore to be used as a support for the superpositive conductive hybrid membranes.

The sintered density was measured using specific gravity scales (Mettler H80, Swiss) and weight scales according to Archimedes' principles, referring to American Society for Testing and Materials (ASTM) C 373-88.

Since kerosene was used instead of water for accurate density measurement, the specific gravity was calculated as 0.8 because it is very sensitive to moisture. When the density was calculated using the measured specific gravity, the relative density was obtained from the theoretically calculated density.

In addition, the morphology of each specimen was examined by SEM (JEOL JSM-6308, Japan) to determine the crystal size and microstructure of the specimen before and after ion exchange.

Hereinafter, the ion exchange rate and the sintering density and microstructure analysis of the ion exchange rate and the ammonium nitrae through the acetic acid for the ion exchange rate and phase analysis of the K ⁺ -β "-alumina sintered body will be described in detail.

As shown in Fig. 4, the ratio of [K ₂ O]: [Al ₂ O ₃ ] is 1: 5, and K ⁺ -β "-alumina powder calcined at 1200 ° C is used for forming-sintering ion exchange. Phase analysis of pellets.

The initial raw material γ-alumina has a cubic close-packed (ccp) structure in the crystal structure, which is similar to the rhombohedral structure that forms the spinel block of β "-alumina. It has been found to be structurally advantageous for β "-alumina formation and to synthesize pure K ⁺ -β" -alumina phase directly.

That is, it was confirmed that the peak of the γ-alumina phase is directly transferred to the K ⁺ -β "-alumina phase (2 0 10, 2 2 0).

As shown in Figure 5 to 8 K ⁺ -β "-aluminas sintered at 1400 ℃ was ion-exchanged to H ₃ O ⁺ -β" -alumina at 150 ℃, 170 ℃, 200 ℃ using acetic acid, The number of times was repeated from 1 to 3 times at 2 hour intervals.

Here, the reaction time shown in FIGS. 6 to 8 includes (a) 1 time, 2h, (b) 1 time, 4h, (c) 1 time, 6h, (d) 1 time, 8h, (e) 2 time, 2h, (f) 2 times, 4h, (g) 2 times, 6h, (h) 2 times, 8h, (i) 3 times, 2h, (j) 3 times, 4h, (j) 3 times, 6h, (j) 3 times, 8h.

The concentrations were also changed to 10 wt.% And 50 wt.%.

Therefore, the ion exchange rate by 10 wt.% Acetic acid increased with increasing number of ion exchange at all temperatures.

Specifically, the one-time ion exchange showed a similar ion exchange rate of about 70% at all temperatures, and the exchange rate increased significantly as the number of ion exchanges increased.

In particular, the two to three ion exchange rates at 170 ° C. increased more than 150 ° C., reaching a maximum of 99.7%. However, in the case of ion exchange at 200 ° C., the sintered body collapsed in the remaining ion exchanges except for one-time ion exchange for 2 hours.

The recovered ion exchange rate of 2 hours was 69%, which was not much different from that of 150 ℃ and 170 ℃.

This is thought to be due to the high partial pressure and increased reactivity of potassium as the temperature rises, thereby changing the potassium ion of K ⁺ -β ″ -alumina to hydronium ion and not maintaining the β ″ -alumina phase. The rapid reaction with OH ^- groups led to a phase change to AlOOH (bohemite).

Increasing ion exchange rates and increasing bohemite phase support this. And this increase in bohemite phase occurs rapidly as the temperature rises.

To investigate the effect of ion exchange rate on the concentration, ion exchange was performed using 50% acetic acid as an ion exchange medium.

Ion exchange through 50% acetic acid was performed once at 2 hours to 8 hours at 150 ℃ for 2 hours, and showed high ion exchange rate of 90-95%. However, K ⁺ -β "-alumina reacted with acetic acid to produce aluminum acetate hydroxide, but could not maintain the β" -alumina phase. The bohemite phase is invisible due to the high concentration of acetic acid, which is more active with acetic acid than with OH ^- groups in ion exchange media.

As shown in Figure 9 to 15, the ion exchange through Ammonium nitrate was ion-exchanged with NH ₄ ⁺ -β "-alumina at 100 ℃, 130 ℃, 150 ℃, 170 ℃, 200 ℃ using ammonium nitrate, Ion exchange was also carried out to ammonium nitrate in the molten state at 200 ℃. The concentrations were changed to 5 M and 10 M. Like acetic acid, it was repeated 1 to 3 times at 2 hour intervals.

Here, the reaction time of FIGS. 9 and 10 is (a) 1 time, (b) 2 times, (c) 3 times, and the reaction time of FIGS. 11 to 14 is (a) 1 time, 2h, (b) 1 time, 4h, (c) 1 time, 6h, (d) 1 time, 8h, (e) 2 time, 2h, (f) 2 times, 4h, (g) 2 times, 6h, (h) 2 times , 8h, (i) 3 times, 2h, (j) 3 times, 4h, (k) 3 times, 6h, (l) 3 times, 8h.

Ion exchange with 10 M ammonium nitrate increases the ion exchange rate with increasing temperature from 100 ℃ to 150 ℃.

Since the ion exchange rate at 170 ℃, 200 ℃ reached 99%, the ion exchange rate was similar to 150 ℃. As with acetic acid, the ion exchange rate increased with increasing number of ion exchanges, and the increase rate of ion exchange rate between 1 and 2 to 3 times was increased in all temperature ranges.

However, at 200 ℃, bohemite was formed under the conditions except for 2 hours of ion exchange, and the phase transition to bohemite was increased as the ion exchange time and the number of ion exchange times increased. In contrast, the molten ammonium nitrate showed a high ion exchange rate of about 99% regardless of the number of times despite the ion exchange at 200 ℃ and maintained the β ″ -alumina phase.

In order to determine the effect of the concentration, ion exchange was performed using 5M ammonium nitrate at 170 ° C. As a result, the ion exchange rate was 1 ~ 2% lower than that of 10M ammonium nitrate, but the increase rate was similar. However, unlike 10M ammonium nitrate, a small amount of phase transition to bohemite was achieved in two 8-hour and three-time ion exchanges. This is due to more OH ⁻ groups than 10 M ammonium nitrate.

The phase transition to bohemite may be formed not only by the reaction with acetic acid or ammonium nitrate but also by water, and its effect is also greater than that of ion exchange media. This can be seen in the high concentration of acetic acid or molten ammonium nitrate, but the bohemite phase does not appear in low concentration of acetic acid or solution ammonium nitrate.

This is supported by the formation of bohemite phase when K ⁺ -β ″ -alumina is reacted with pure water at 150 ° C for 8 hours.

As shown in FIG. 16, K ⁺ -β "-aluminas were sintered at three sections of 1300 ° C, 1400 ° C, and 1500 ° C. As shown in FIG. 16, the relative density of K ⁺ -β" -aluminas increased in temperature. As the relative density increases, the highest relative density was obtained at 1500 ° C.

However, the high relative density acts as a barrier to the penetration of solid acids, making it difficult to penetrate many solid acids. The lowest relative density of 1300 ℃ was not sintered to the same value as the green density and did not have a suitable strength for use as a support.

K ⁺ -β "-aluminas sintered at 1400 ℃, which can be used as a support with appropriate strength and have a low relative density, were used as a support.

As shown in FIG. 17, when the SEM photograph of K ⁺ -β "-aluminas sintered at 1400 ° C. is seen, the sintering of the K ⁺ -β ″ -aluminas powder occurs in the SEM photograph to clearly distinguish the part where densification is made and the part that is not. It is done. This is the part where solid acid penetrates into the area where this densification has not been achieved and recrystallization takes place.

Preparation of Superproton Conductive Hybrid Membranes

Reference to the drawings will be described in detail with respect to the raw materials and compositions for the production of super-proton conductive hybrid membranes, solid acid synthesis, phase analysis, density and microstructure analysis of the composite, ionic conductivity measurement.

The synthesis of zirconium phosphate to penetrate K ⁺ -β "-aluminas with ion exchange is possible in the following five examples.

Example 1 ZrOCl in Aqueous Solution ₂ 8H ₂ H to O ₃ PO ₄ Synthesis by adding (see Figs. 18A to 18G)

(1) Prepare a ZrOCl ₂ 8H ₂ O solution containing 1 M moisture.

(2) Then, the addition of a 1M H ₃ PO _4.

(3) After washing, dry at 368 K for 2 hours.

Example 2 ZrOCl ₂ 8H ₂ After dissociating O in HCl, diluted H ₃ PO ₄ Synthesis by adding (see Figs. 19A to 19G)

(1) Dissociate ZrOCl ₂ 8H ₂ O into 2M HCl.

(2) Mix 1.3 M dilute H ₃ PO ₄ at 1000 rpm for 1 hour.

(3) filtered and washed with 0.3 MH ₃ PO ₄ .

(4) Process after drying for 2 hours at 368K.

Example 3 ZrP Synthesis Using Surfactant Aniline and Span-Tween (See FIGS. 20A-20M)

(1) Dissolve the surfactant Aniline and span-tween in ethanol.

(2) Adjust the PH by adding HCl below PH = 2.

(3) Mix zirconium ions for 2 hours.

(4) Phosphoric acid is added.

(5) After 2 hours, stop mixing and age the mixture.

(6) After filtering, washed with ethanol and dried at 120 ℃.

Example 4 Spherical ZrP Synthesis Using Sol-gel Method (see FIGS. 21A-21G)

(1) 1.79 g ZrOCl ₂ 8H ₂ O is dissolved in distilled water.

(2) (NH ₄ ) ₂ CO ₃ is added to the solution.

(3) (NH ₄ ) ₂ HPO ₄ is added to the solution.

(4) Store in oven at 80 ℃ for 3 days.

(5) Aged at 120 ° C for 2 days at 90 ° C for 2 days.

(6) After cooling, filtering, washing and drying.

(7) Calcination at 540 ° C. for 6 hours.

Example 5 ZrOCl in Aqueous Solution ₂ 8H ₂ H to O ₃ PO ₄ ZrP synthesis by adding HF and HF (see FIGS. 22A to 22G).

(1) ZrOCl ₂ 8H ₂ O is dissolved in water.

(2) Add H ₃ PO ₄ and Hydrofluoric acd.

(3) Aged at 80 ° C. for 7 days.

< Example  6> Superproton  conductivity hybrid membranes Manufacture

The preparation of super-proton conductive hybrid membranes was made using NH ₄ ⁺ -β "-alumina, which showed a stable phase and high ion exchange rate, and infiltrated the zirconium phosphate as a solid acid into porous NH ₄ ⁺ -β" -aluminas. It was.

Claims (7)

H ₃ O ⁺ / NH ₄ ⁺ -β ″, a super ionic conductor ion-exchanged with acetic acid and ammonium nitrate using K ⁺ -β "-alumina as a precursor A method for producing a super-proton conductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina, which is prepared by infiltrating zirconium phosphate as a conductive solid acid with alumina as a support. The method of claim 1,
The zirconium phosphate,
Preparation of super-proton conductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina, prepared by adding H ₃ PO ₄ to water-containing ZrOCl ₂ 8H ₂ O solution, washing and drying at 368 K Way . The method of claim 1,
The zirconium phosphate,
ZrOCl ₂ 8H ₂ O was dissolved in 2M HCl, dilute H ₃ PO ₄ at 1000rpm, filtered, washed with H ₃ PO ₄ , dried at 368K and processed. Method for Producing Super Positive Electroconductive Hybrid Membrane Using Proton-Beta-Alumina. The method of claim 1,
The zirconium phosphate,
Dissolve the surfactant Aniline and span-tween in ethanol, adjust by adding HCl to PH = 2 or less, mix zirconium ions, add phosphoric acid, age the mixture, filter, wash with ethanol, 120 ℃ A method for producing a super-proton conductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina, which is prepared by drying with a silica gel. The method of claim 1,
The zirconium phosphate,
After dissolving ZrOCl ₂ 8H ₂ O in distilled water, (NH ₄ ) ₂ CO ₃ and (NH ₄ ) ₂ HPO ₄ are added to the solution, and then stored in an oven at 80 ° C., and then at 90 ° C. and 120 ° C. A method for producing a superprotonically conductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina, which is prepared by aging, cooling, filtering, washing and drying and calcining at 540 ° C. The method of claim 1,
The zirconium phosphate,
ZrOCl ₂ 8H ₂ O is dissolved in water, and H ₃ PO ₄ and hydrofluoric acid is added, and then prepared by aging at 80 ℃ ultra-conductive electroconductive hybrid membrane using zirconium phosphate solid acid and proton-beta-alumina Way . The method of claim 1,
The K ⁺ -β "-alumina (alumina) is sintered at 1400 ℃ using a zirconium phosphate solid acid and proton-beta-alumina super-proton conductive hybrid membrane manufacturing method.

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