JPS59195057A - Optical energy conversion system - Google Patents

Abstract

PURPOSE:To increase the solar energy conversion efficiency of the titled system by a method wherein in the case of the optical energy conversion system using a photochemical heat storage material adopted to convert solar energy into thermal energy for the collection and storage of heat, the photochemical heat storage material is temporarily isolated from a reaction system during or after the application of the solar rays upon the material. CONSTITUTION:A cyclohexane solution of trans-azobenzene refined by recrystallization is received within a qualtz cell 4 and the solar rays are applied on the solution at normal temperature. Then, after the application of the solar rays, the solution is circulated and cis-azobenzene generated from the solution is absorbed completely by an absorbing column 6 through a liquid inlet port. After that, the circulation of the solution is stopped and then the application of the sunlight on the solution is performed and so on in a repetitive fashion during which only non-reacted trans-azobenzene is repeatedly applied with the sunlight. Consequently, the solar energy conversion efficiency of the system increases remarkably as compared to a case where the absorbing column 6 is not used. The generated substance absorbed by the column 6 is used after it is transferred into a storage tank by heating the column or by adding a solution of a separating agent to the column.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light energy conversion system for improving the conversion efficiency in a photochemical heat storage material that collects and stores heat at the same time by chemically converting sunlight energy.

In general, solar energy is widely and thinly dispersed as it is as it is irradiated by the sun, and also fluctuates drastically, so it is necessary to smooth it by concentrating and storing it before use. One of these methods is the photochemical heat storage method.

This mainly utilizes photochemical reactions of photochemical heat storage materials represented by photoactive organic compounds, such as isomerization and trimerization, to convert sunlight energy into chemical energy, which increases the enthalpy of the generated substances and enables long-term storage. At the same time, when there is demand, a reverse reaction occurs to release the stored energy and use it as heat.

Figure 1 shows an outline of the solar energy conversion and storage system using the photochemical heat storage material described above. It can be circulated continuously or intermittently within the system 3. Then, in the condensing cell, it is irradiated with sunlight, causing isomerization and dioxidization, and after collecting and storing heat, it passes through a conversion detector and is stored in a storage tank.

The photochemical heat storage material used in this solar energy conversion needle XaM absorbs light of a wavelength corresponding to the absorption band of the photosensitizer itself or added, and changes into a high-energy isomer.

However, the conversion is not 100% complete, and generally the generated high-energy generated substances are simultaneously irradiated with light and return to the original substance, so initially the amount of generated substances increases linearly, but the rate of increase is gradually decreases, and with long irradiation, a photochemical equilibrium state is usually reached, which is independent of the irradiation time.

Table 1 shows the light wavelength and the content of cis-azobenzene at photochemical equilibrium with respect to the photoisomerization of trans-azobenzene into the cis form, and it can be seen that equilibrium is reached at a low conversion rate.

Table 1 Therefore, even if the system shown in Figure 1 is used for long periods of irradiation and circulation, after reaching photochemical equilibrium,
The amount of produced substances does not increase any further and the rate of change remains low, but the active substances are wasted due to side reactions.
If this continues, efficient energy storage cannot be achieved. In addition to photochemical equilibrium, conversion efficiency also decreases due to accumulation of produced substances in the solution.

As described above, the system shown in Figure 1 does not improve the conversion efficiency of photochemical heat storage materials, but no attempt has been made to improve the conversion efficiency of photochemical heat storage materials using an industrially feasible method. do not have.

In view of the above-mentioned circumstances, the present inventors conducted intensive research on a solar energy conversion system to improve the conversion efficiency of photochemical heat storage materials, and as a result, the present inventors converted light energy into photochemical heat storage materials by e.g.
In a light energy conversion system that causes a photochemical reaction to occur and stores the absorbed light energy as an enthalpy increase in the reaction product, the product is temporarily converted to an anti-1 during or after light irradiation. Noshi: It was discovered that by isolating it from the system, the conversion rate to the product substance can be significantly improved.

must be continuously removed from the reaction system by some method.

In this invention, by temporarily isolating the produced substance from the reaction system during or after light irradiation, the conversion efficiency to the produced substance can be significantly improved without impairing the function of the light energy conversion system. It is possible.

The first method of temporarily isolating the produced substance from the reaction system is to create an environment where the photochemical heat storage material and the reaction produced substance coexist in a state of υ:q.
A column filled with an adsorbent is provided in the circular path, and the reaction product is selectively adsorbed into the adsorbent.

Note that the adsorbed product substance can be transferred to a storage tank and used by heating the column or adding a desorption solvent to the column.

The above method is performed by inserting, for example, an activated alumina adsorption column into the circulation system in a light energy conversion system using the isomerization reaction from the trans form of azobenzene to the cis form, and dissolving azobenzene in a cyclohexane solvent. This can be achieved by passing it through an adsorption column.

That is, since cis-azobenzene is more strongly adsorbed on alumina than trans-azobenzene, the outflow rate of the cis-form in cyclohexane solvent is about one-fourth that of the trans-form.
becomes. Therefore, the cis-azobenzene produced by light irradiation is adsorbed by alumina and concentrated during the circulation of the reaction solution, and simultaneously removed from the reaction solution, so only unreacted trans-azobenzene circulates within the system and is irradiated with light. receive. As a result, the conversion rate increases significantly compared to when the adsorption column is not used.

In this example, it is not necessary to constantly circulate during the light irradiation, but the circulation is stopped while the produced substance increases linearly with time, and then the operation of circulating adsorption is repeated for the necessary time. If adopted, it will be efficient. Furthermore, if the adsorption column is kept in a cool place, its efficiency will further increase.

The above explanation was for azobenzene, but this method can also be applied to azobenzene derivatives. Also, in the norbornajun-quadoricyclene cycloaddition reaction system, the outflow rate from the adsorption column is significantly higher for quadricyclene than for flubornadiene. Since it is slow, this method can also be applied to norbornadiene and its derivatives.

In addition, the adsorbent packed into the column in the above method is not limited to activated alumina, and various adsorbents can be selected depending on the type of heat storage material to be applied.

Furthermore, as a solvent to be passed through the column, in addition to the above-mentioned cyclohexane, hexane, methyl alcohol benzene, petroleum benzine, and a mixed solvent thereof can be used.

In addition, the cis-azobenzene adsorbed as described above can be easily transferred to a storage tank by circulating the reaction solution while heating the column a little or, depending on the case, by desorbing it with a different solvent such as ether.

As a second method to temporarily separate the produced substance from the reaction system, it is possible to temporarily isolate the produced substance outside the reaction system by utilizing the difference in solubility in the solvent between the photochemical heat storage material and the reaction product. It is.

If we look at this with azo and benzene, trans-type and cis-type azobenzene have a large difference in polarity between the source substance and the product due to the shape of the molecule, so the solubility of the source substance is large, and the solubility of the product substance is large. A solvent or a mixed solvent with a small amount can be selected. For example, the solubility of trans-azobenzene in petroleum ether is 351-/43 in OC.
That of cis-azobenzene is 90 g/! However, its solubility further decreases in the coexistence of trans-Tzobenzene. Therefore, if the raw material is dissolved in a solvent with such properties at a high concentration and irradiated with light, the product will remain in a solution state as the temperature is usually increased during the irradiation, but after circulation. In a cold place or storage, the product material precipitates and the reaction solution becomes enriched in the raw material again, making it possible to achieve the same improvement in conversion rate as in the first method.

Although petroleum ether is exemplified as the above solvent, petroleum benzene or a mixed solvent of petroleum ether and petroleum benzine may also be used.

In summary, according to the present invention, it is possible to dramatically increase the conversion rate of a photochemical heat storage material into a high-energy substance in a light energy conversion system as shown in FIG. Storage can be realized.

Examples of this invention will be shown below.

Example 1 FIG. 2 shows a solar energy conversion and storage system used in this example. Compared to the system shown in FIG. The system has the same configuration as the system shown in Figure 1, except that a recorder g is connected to the conversion detector S, and similar components will be described using the same numbers. omitted.

Also, the condensing cell has a thickness of 5 mm, a width of 1 otb, and a height of 1
The adsorption column t was composed of a cylinder having a diameter of 1 rytrb and a length of about 10 orb and filled with activated alumina.

In one or more of the systems, the quartz cell contains about 10 ml of a cyclohexane solution of trans-azobenzene purified by recrystallization (concentration 10 Li/-/, 8), and the wavelength is 340 nm (7,2×104 erg/d・se
The light of c) was irradiated for 35 hours at room temperature.

After irradiation, circulation was performed for 10 minutes at a flow rate of 0.4 mlj/mjn, and the product cis-azobenzene was transferred from the liquid inlet to the adsorption column (diameter 1, length approximately 100 nm) shown in Figure 2. It was completely absorbed into the width of 5711411. When the circulation was stopped and irradiation was performed again, the same operation was performed, and the width of the adsorbed cis-azobenzene was approximately 1.2%, or it was completely adsorbed, and the unabsorbed cis-azobenzene (only the trans-azobenzene was irradiated repeatedly) By circulating the solution while heating the adsorption column with a hot air blower, cis-azobenzene was easily desorbed into the solution.

Example 2 A cyclohexane solution containing acetophenone as a photosensitizer to norbornadiene purified by distillation under reduced pressure
Irradiated with 640 lm light in exactly the same manner as in 37, and exposed Noriho/I/-3". I was able to efficiently convert it to Quad\Cyclen.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a light energy conversion system using a conventional photochemical heat storage material, and FIG. 2 is a schematic diagram of a light energy conversion system showing an embodiment of the present invention. Among them, 3 is the circulatory system, G is the condensing cell, and O is the IN column.

Claims (4)

[Claims] (1) In a light energy conversion system in which a photochemical heat storage material absorbs light energy, performs a photochemical reaction, and stores the absorbed light energy as an enthalpy increase of the reaction product, the product is A light energy conversion system characterized by being temporarily separated from the reaction system after irradiation. (2) As a means for temporarily isolating the product from the reaction system, a column filled with an adsorbent is provided in the path where the photochemical heat storage material and the reaction product circulate in a coexisting state. A light energy conversion system as described. (3) The light energy conversion system according to claim 1, wherein a solvent in which the produced substance has a low solubility is used as a solvent for the photochemical heat storage material as a means for temporarily isolating the produced substance from the reaction system. (4) The optical energy conversion system according to claim 1, 2, or 6, wherein the photochemical heat storage material is selected from azobenzene, norbornadiene, and derivatives thereof.