JP2002336685A - Method for predicting photocatalyst reaction and system for the same as well as program and recording medium for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of predicting a photocatalyst reaction which is capable of easily predicting the photocatalyst reaction for a treatment object and judging the applicability thereof and a system for the same as well as a program and recording medium or the same. SOLUTION: Data base 11 and 12 store the standard oxidation reduction potential of a reaction system relating the conduction band and valence electron band of the photocatalyst and a sample substrate and pretreating means 1 corrects the oxidation reduction potential by computation from the pH of the reaction system and the standard oxidation reduction potential relating to the photocatalyst and sample substrate existing in the reaction system from the date base 12. Arithmetic processing system 2 determines which reaction of the oxidation reaction and the reduction reaction occurs preferentially in accordance with the result of the computation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting an oxidation-reduction reaction (hereinafter, referred to as a photocatalytic reaction) caused by a photocatalyst, an apparatus therefor, a program, and a recording medium therefor.

[0002]

2. Description of the Related Art Photocatalysis has been a process that can convert light energy into chemical energy since the discovery of photosensitized decomposition of water on a titanium dioxide (TiO ₂ ) electrode by Honda and Fujishima in the 1970s. , Its application has attracted worldwide attention.

[0003] As shown in FIGS. 2 (a), (the case of TiO _2, the wavelength of this light 410nm or less) light having the band gap (in the case of TiO ₂ 3.2 eV) or more energy to a photocatalyst when irradiated with Then, electrons are excited from the valence band to the conduction band to generate holes and electrons.

[0004] Harmful substances in the air and water can be decomposed and removed by utilizing the strong redox power of the holes and electrons. Generally OH radicals are generated by the holes and water reacts in the valence band in water, also superoxide anion reacts oxygen molecules of electrons and water at the conduction band (· O ₂ ^-) active oxygen, such as Seeds have been found to form. That is, on the photocatalyst surface, the oxidation reaction and the reduction reaction proceed simultaneously.

[0005] However, since the decomposition reaction treatment method of an organic substance using a photocatalyst is a surface reaction in which the diffusion of a substance onto the surface of the photocatalyst is rate-determining, the reaction takes time and there is a limitation in application. . For this reason, methods of using a gas phase reaction or combining an oxidizing agent such as ozone to improve the reaction efficiency have been studied.

[0006] In addition, in order to take advantage of the original feature of the photocatalyst that natural light can be used, development of a water purification system using sunlight has been energetically performed.

[0007] At present, examples of application of TiO ₂ photocatalyst include removal of NOx, SOx, etc., decomposition of odor and maintenance of freshness.
_2. Products that focus on the high organic substance resolution of photocatalysts have been commercialized. Although these products use the strong oxidizing power of TiO _{2 in} the atmosphere, research has been focused on the reducing power of TiO ₂ when used in water.

[0008]

By the way, in the field of water treatment, especially in the field of water purification, research on alternative chlorine disinfection has been actively conducted due to deterioration of raw water quality. There is ozone treatment as a typical method of processing therein, bromide ion in the raw water subjected to ozone treatment (Br ^-) Br by the contains ozone (O ₃₎ ^- is oxidized suspected as carcinogen of certain bromate ion (BrO ₃ ^-) are generated (Fig. 2
(B)). Then, BrO ₃ This generated ^- the decomposition of it becomes a very effective means of using the reducing power of the photocatalyst.

Therefore, the present inventors focused on the reducing power of such a photocatalyst, and denitrified by the reducing power (see FIG. 2).
A test was made to see if (c)) could be expected. If a denitrification effect can be expected, its application to lakes and marshes and sea areas, which are currently a problem in eutrophication, can be sufficiently considered.

[0010] However, denitrification not observed at all, on the contrary, nitrite ion (NO ₂ ^-) from nitrate ion (N
Only the oxidation reaction to O ₃ ⁻ ) was confirmed (FIG. 3).

As described above, although the photocatalyst has a strong oxidizing power and a reducing power, its reaction depends on the object to be treated and its form is different. Therefore, when a photocatalyst treatment, for example, with respect to application to water treatment, the characteristics of the raw water, BrO ₃ ^- disassemble only not confirmed reaction of, BrO ₃ ^- but was degraded, new other It is quite possible that harmful substances are generated.

Therefore, before actually applying the photocatalytic treatment, it is necessary to grasp whether or not this treatment method is effective. At present, however, no research has been made on the development of the method.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a photocatalytic reaction prediction method, a photocatalytic reaction prediction method, an apparatus and a program, which can easily predict a photocatalytic reaction for a treatment object and judge its applicability. Provision of the medium.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an invention according to claim 1 is a method for predicting a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present, and the method comprises the steps of: A step of correcting the conduction band and the valence band of the photocatalyst based on the pH value of the system that reacts with the substrate, and the standard oxidation-reduction potential of the reaction system related to the substrate,
Ordering the corrected redox potential in order of potential,
A step of determining, from the result of the regulation of the oxidation-reduction potential, the state of promoting the inhibition of the oxidation or reduction reaction of the sample substrate caused by the photocatalyst.

According to a second aspect of the present invention, in the method for predicting a photocatalytic reaction according to the first aspect, after adjusting the corrected oxidation-reduction potential in the order of potential, a reaction path of a sample substrate that can occur by the photocatalyst is obtained; A step of deciding whether or not a reaction of the sample substrate caused by the photocatalyst occurs, or if the reaction occurs, determining whether the reaction is an oxidation reaction or a reduction reaction.

According to a third aspect of the present invention, in the method for predicting a photocatalytic reaction according to the second aspect, a step of selecting one of the substance names in the obtained reaction path, and simultaneously performing an oxidation reaction and a reduction reaction on this substance. A step of determining whether or not to proceed, and when the oxidation reaction and the reduction reaction proceed simultaneously, calculate the Gibbs free energy of the oxidation reaction and the reduction reaction by calculation from the corrected oxidation-reduction potential, and calculate the A step of determining which of the oxidation reaction and the reduction reaction occurs preferentially.

According to a fourth aspect of the present invention, there is provided an apparatus for predicting a photocatalytic reaction in a reaction system in which a photocatalyst and a sample substrate are present, and an input means for inputting a photocatalyst name, a sample substrate name, and a pH value of the reaction system. A recording means for recording in advance the standard oxidation-reduction potential of the reaction system involving the conduction band and valence band of the photocatalyst and the sample substrate; a pH value of the reaction system; Pretreatment means for supplying a standard oxidation-reduction potential value relating to the photocatalyst and the sample substrate, and correcting the oxidation-reduction potential by calculation from these values;
The oxidation-reduction potential corrected by the pre-processing means is supplied,
An arithmetic processing means for determining, based on the value of the oxidation-reduction potential, the promotion of the inhibition of the oxidation or reduction reaction of the sample substrate caused by the photocatalyst; and the inhibition of the oxidation or reduction reaction of the sample substrate determined by the arithmetic processing means. Means for outputting the promotion status as a reaction prediction result.

According to a fifth aspect of the present invention, in the photocatalytic reaction predicting apparatus according to the fourth aspect, the arithmetic processing means is configured to perform a calculation based on a value of an oxidation-reduction potential supplied from the preprocessing means.
The method is characterized in that a reaction path of a sample substrate that can be caused by a photocatalyst is obtained, and the presence or absence of a reaction or, if a reaction occurs, whether it is an oxidation reaction or a reduction reaction is determined by calculation.

According to a sixth aspect of the present invention, in the photocatalytic reaction prediction device according to the fifth aspect, when the arithmetic processing means determines that the oxidation reaction and the reduction reaction proceed simultaneously in each of the substances in the obtained reaction path, Gibbs free energy is calculated by calculation from the value of the oxidation-reduction potential supplied from the preprocessing means, and based on the calculation result, which of the oxidation reaction and the reduction reaction occurs preferentially is determined. To do.

According to a seventh aspect of the present invention, in order to predict a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present, a computer is used to input a photocatalyst name, a test substrate name, and a pH value of the reaction system. Means, in advance, a recording means for recording the standard oxidation-reduction potential of the reaction system involving the conduction band and valence band of the photocatalyst and the test substrate, and the pH value of the reaction system,
Pre-processing means for supplying a standard oxidation-reduction potential value relating to a photocatalyst and a sample substrate present in the reaction system from the recording means, and correcting the oxidation-reduction potential by calculation from these values; and The corrected oxidation-reduction potential is supplied, and based on the value of the oxidation-reduction potential, an arithmetic processing unit that determines the inhibition promotion state of the oxidation reaction or the reduction reaction of the test substrate caused by the photocatalyst, and the arithmetic processing unit determines the state. A photocatalytic reaction prediction program for functioning as a means for outputting the inhibition promotion status of the oxidation or reduction reaction of the test substrate as a reaction prediction result.

According to an eighth aspect of the present invention, in the photocatalytic reaction prediction program according to the seventh aspect, the arithmetic processing means is a sample substrate which can be generated by the photocatalyst based on the value of the oxidation-reduction potential supplied from the preprocessing means. Is obtained by calculating the presence or absence of a reaction or, if a reaction occurs, whether it is an oxidation reaction or a reduction reaction.

According to a ninth aspect of the present invention, in the photocatalytic reaction prediction program according to the eighth aspect, the arithmetic processing means determines that the oxidation reaction and the reduction reaction proceed simultaneously in each of the substances in the obtained reaction path. Calculating the Gibbs free energy by calculation from the value of the oxidation-reduction potential supplied from the preprocessing means, and determining which of the oxidation reaction and the reduction reaction occurs preferentially based on the calculation result. Deciding.

According to a tenth aspect of the present invention, in order to predict a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present, a computer is used to input a photocatalyst name, a test substrate name, and a pH value of the reaction system. Means, recording means for recording in advance the conduction and valence bands of the photocatalyst, and the standard oxidation-reduction potential of the reaction system involving the test substrate, pH value of the reaction system, and the presence of the reaction system from the recording means. And the value of the standard oxidation-reduction potential related to the photocatalyst and the test substrate,
Pretreatment means for correcting the oxidation-reduction potential by calculation from these values, and an oxidation-reduction potential corrected by the pretreatment means are supplied. Based on the value of the oxidation-reduction potential, an oxidation reaction of the test substrate caused by the photocatalyst is performed. Or, a photocatalyst for functioning as arithmetic processing means for determining the inhibition promotion status of the reduction reaction, and means for outputting the oxidation promotion or reduction inhibition inhibition status of the test substrate determined by the arithmetic processing means as a reaction prediction result It is a computer-readable recording medium recording a reaction prediction program.

According to an eleventh aspect of the present invention, in the computer readable recording medium having recorded thereon the photocatalytic reaction prediction program according to the tenth aspect, the arithmetic processing means comprises:
On the basis of the value of the oxidation-reduction potential supplied from the pretreatment means, a reaction path of the sample substrate that can occur by the photocatalyst is obtained, and the presence or absence of a reaction, or, if the reaction occurs, an oxidation reaction or a reduction reaction is determined by calculation. To do.

According to a twelfth aspect of the present invention, in the computer readable recording medium having recorded thereon the photocatalytic reaction prediction program according to the eleventh aspect, the arithmetic processing means comprises:
In each of the substances in the obtained reaction path, when it is determined that the oxidation reaction and the reduction reaction proceed simultaneously, the Gibbs free energy is calculated by calculation from the value of the oxidation-reduction potential supplied from the pretreatment means, and the calculation result is And determining which of the oxidation reaction and the reduction reaction occurs preferentially.

According to the photocatalytic reaction prediction method, the apparatus, the program, and the recording medium according to the present invention described above, since the redox potential and Gibbs free energy of the photocatalyst and the coexisting substance are taken into consideration, the photocatalyst is considered. Thus, it is possible to determine the possibility of promoting the inhibition of the oxidation reaction or reduction reaction caused by the reaction, and to predict the priority of the reaction.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

Since the reaction occurring on the surface of the photocatalyst is an oxidation-reduction reaction due to the transfer of electrons, it is considered that the ease of taking in and releasing electrons, and the magnitude of the energy at that time, become problems. .

Therefore, there is a standard oxidation-reduction potential (E ⁰ ) as an index of the ease of taking in and releasing electrons.
In addition, there is a standard cast free energy (ΔG ⁰ ) as an index for checking the magnitude of the energy at that time.

Here, E⁰And ΔG⁰About the view of oxidation
Body A^{n +}Reaction system A of^{n +}+ Ne ^-→ Take A as an example
explain.

First, assuming that the magnitude of the oxidation-reduction potential difference in the following reaction formula (1) is E, E is expressed by formula (2) by Nernst's formula.

A ^{n +} + ne ⁻ → A (1) E = E ⁰ + RT · (nF) ⁻¹ · ln ([A ⁺ ] / [A]) (2) E ⁰ : standard redox potential R : Gas constant T: absolute temperature n: number of electrons involved in the reaction system F: Faraday constant In the formula (2), [A ⁺ ] and [A] indicate activity, but [A ⁺ ] and [A] Is a molar concentration when it is a solute (liquid or solid), and a molar partial pressure when it is a gas.

E changes depending on the pH of the reaction system.

Here, in (1), for example, the change in E due to pH when the oxidant A ^{n +} is NO ₃ ⁺ and the reductant A is NO ₂ ⁻ will be considered.

NO ₃ ⁻ + 2H ⁺ + 2e ⁻ → NO ₂ ⁻ + H ₂ O (3) The Nernst equation in the above reaction equation (3) is the following equation (4).

E = E ⁰ + RT · (2F) ⁻¹ · ln (([NO ₃ ⁻ ] · [H ⁺ ] ² ) / ([NO ₂ ⁻ ] · [H ₂ O])) (4) In equation (4), the photocatalytic reaction prediction according to the present invention is NO
It is believed that ₃ ^- and equimolar NO ₂ ^- are produced and [H ₂ O] = 1.
Further, since ln [H ⁺ ] = 2.303 log ₁₀ [H ⁺ ] = − 2.303 pH, the equation (4) can be expressed as the following equation (5). This is,
The arithmetic expression for E ⁰ correction considering the pH in the reaction formula (3).

E = E ⁰ + RT · (2F) ⁻¹ · ln (([NO ₃ ⁻ ] · [H ⁺ ] ² ) / ([NO ₂ ⁻ ] · [H ₂ O])) = E ⁰ + RT · (2F) ⁻¹ · ln [H ⁺ ] ² = E ⁰ + 2RT · (2F) ⁻¹ · ln [H ⁺ ] = E ⁰ −2.303RT · F ⁻¹ · pH (5) And above As is clear from the above, the Nernst equation considering the pH in the reaction system relating to the oxidant per unit mole may be expressed by the following equation (6).

E = E ⁰ −2.303 · mRT · (nF) ⁻¹ · pH (6) m: Coefficient of hydrogen ion involved in the reaction system n: Number of electrons involved in the reaction system As described above. In the photocatalytic reaction, electrons are exchanged on the surface of the photocatalyst. Therefore, the ease of exchange of electrons between the proceeding reaction system and the photocatalyst becomes a problem.
Therefore, the use of this E ⁰ becomes an effective means as the index.

In the Nernst equation, the smaller the ^value of E ⁰ , the more the system is a reaction system that easily emits electrons (a system in which an oxidation reaction is likely to occur). It indicates that the system is a system (a system in which a reduction reaction easily occurs).

FIG. 4 is an explanatory diagram of how to view the oxidation-reduction potential in the photocatalytic reaction when the solvent is water.

Assuming a photocatalytic reaction when the solvent is water, the prediction of the photocatalytic reaction according to the present invention is based on E ⁰ (O ₂ / H ₂ O) between oxygen (DO) dissolved in water and water. Is the reference potential. At this time, if the potential of the sample reaction system is between the reference potential and the potential of the conduction band, the system is determined to be a system that easily emits electrons. If it is between the two, it is determined that the system is easy to take in electrons.

E ⁰ is a judgment index for inhibiting or accelerating a target oxidation-reduction reaction.

Reduction treatment system using photocatalyst (oxidation treatment system)
In, when a reduction reaction (oxidation reaction) is to be promoted, a substrate that causes an oxidation reaction (reduction reaction) may be coexistent in the treatment system, and when a reduction reaction (oxidation reaction) is to be inhibited, the same reduction reaction is required. It is known that a substrate that causes a reaction (oxidation reaction) may be coexisted.

FIG. 5 is a characteristic diagram showing the behavior of the BrO ₃ ^- concentration in the case where NO ₂ ^- is coexisted and in the case where NO _2- is not present. According to this, BrO ₃ ^- than the reduction rate of, ^- BrO ₃ in sole system
It has been shown that the reduction rate is large ^- BrO ₃ of systems coexist ^- NO ₂ to cause an oxidation reaction.

FIG. 6 is a characteristic diagram showing the behavior of the BrO ₃ ^- concentration when ClO ₂ ^- is coexisted and when it is not. According to this, ClO ₂ to cause the same reduction reaction ^- in the coexistence is not a system, ClO ₂ ^- since the reduction reaction is complete BrO ₃ ^- and so the reduction starts, can prioritize the reaction, Br
O ₃ ^- reduction is shown to be inhibited for.

[0046] In this case, ClO ₂ ^- According to the BrO ₃ ^- describes the mechanism of inhibition of the reduction.

FIG. 7 shows the standard oxidation-reduction potential of the main reaction system.

According to this, the direct exchange of electrons is performed.
E in two reaction systems⁰The greater the difference between the values, the more
The original reaction rate will increase. Where BrO_Three ^-Is TiO_Twoof
BrO from the conduction band^-Reaction system reduced to
And TiO_TwoConduction band E⁰Based on the value, the conduction band E⁰Value and
BrO_Three ^-/ BrO^-System E⁰Value difference and conduction band E⁰Value and ClO _Two ^-/
ClO^-System E⁰Considering the difference in values, the occurrence of reduction
Susa is (ClO_Two ^-→ ClO ^-)> (BrO_Three ^-→ BrO^-). So
For, ClO_Two ^-And BrO_Three ^-Priorities in response to
And BrO_Three ^-Will be inhibited.

[0049] It should be noted, BrO ₃ ^- / BrO ^- system, ClO ₂ ^- / ClO ^- than the system,
BrO ^- / Br ^- system, ClO ^- / Cl ^- system is also seen that the larger the reduction rate of, BrO ^-, ClO ^- is not necessarily exist in the reaction system from the beginning, BrO ₃ ^-, ClO ₂ ^- it is caused by the reaction of. Therefore, BrO ^- and ClO ^-, since each is reduced at a rate greater than the rate that is generated, accumulated without Br ^-, Cl ^- is converted to.

Next, NO ₂ ^- BrO by ₃ ^- describing the mechanism of promotion of reduction.

According to FIG._Three ^-In the case of a single system, it is charged
E of child belt⁰O with the largest difference from the value_Two/ H _TwoO-based oxidation reaction
Proceeds preferentially in the valence band. Where NO_Two ^-That exists
Becomes NO_Three ^-/ NO_Two ^-The system is O_Two/ H_TwoOxidation reaction speed faster than O system
Because the degree is large (Fig. 7), NO_Two ^-→ NO_Three ^-Is dominant
Will be. At this time, the conduction band
BrO_Three ^-The rate of reduction of_Three ^-Reduction
Will be promoted.

Although the reduction rate of the BrO ⁻ / Br ⁻ system is higher than that of the BrO ₃ ⁻ / BrO ⁻ system, BrO ⁻ does not exist in the reaction system from the beginning, and the reduction of BrO ₃ ⁻ to be further reduced at a greater rate than is produced, ^- BrO caused by
It is converted to ^- Br without accumulating.

Since the E ⁰ value changes according to the pH, p 0
Correction term of Nernst equation considering H (Equation (6) second)
Item). In this case, the priority of the reaction changes due to the change in pH.

In a reaction system in which only a single substrate is present, no change is observed in the reaction itself even when the pH is changed (for example, an oxidation reaction system remains oxidized even when the pH is changed).
However, in a system in which two or more substrates coexist, the change in pH changes the priority of the reaction.

In the examples of Tables 1 and 7, when the priority of the oxidation reaction is pH = 0, (I ⁻ / I ₃ ⁻ )> (I ₂ / I ₃ ⁻ )> (N
_{^{O 3 - / NO 2 -)}} > (IO 3 - / IO -)> (ClO 3 - / ClO 2 -)> (NO 2 - /
NO), whereas when pH = 5, (I ⁻ / I ₃ ⁻ )> (NO ₃ ^{−
_{/ NO 2 -)> (NO}} 2 - / NO)> (IO 3 - / IO -)> (I 2 / I 3 -)>
(ClO ₃ ⁻ / ClO ₂ ⁻ ).

Similarly, the priority of the reduction reaction slightly changes.

Here, a liquid phase system, a reaction environment for predicting a photocatalytic reaction in a system in which two or more substrates are present,
In particular, the reaction in water was considered, but the E ⁰ value was determined for the reactions of all the substances present in the reaction system, and the oxidation reaction in the valence band was started from the reaction with the largest difference between the valence band and the E ⁰ value. But,
Assuming that the reduction reaction occurs in the conduction band in order from the reaction having the largest difference with the E ⁰ value of the conduction band, it is possible to predict the photocatalytic reaction in all liquid phase systems. Further, in the gas phase system, as shown in FIG. 10, if the same consideration is made as in the liquid phase system, the photocatalytic reaction can be predicted.

As described above, the objective of the photocatalytic reaction prediction according to the present invention is to compare the E ^{0 of the} oxidation-reduction reaction involving each substrate when two or more substrates exist in a certain reaction system. This makes it possible to predict the inhibition or promotion of the photocatalytic reaction.

On the other hand, ΔG ⁰ is expressed by the following equation (1).
In the case where the oxidant A ^{n +} receives e ⁻ from the conduction band of the photocatalyst (a), and in the case where the reductant A provides e ⁻ to the valence band of the photocatalyst (b), how much e ⁻ moves, Energy is consumed.

ΔG ⁰ indicates that the reaction is more likely to proceed to the production system (to the right in reaction equation (1)) as the value is negative and the absolute value is larger. The larger the value is, the easier the reaction proceeds to the original system (to the left in the reaction formula (1)). (A) When the oxidant ^{An +} receives e ⁻ from the conduction band of the photocatalyst ΔG ⁰ = −F · n · (E ⁰ _A1 −E ⁰ _C1 ) (7) F: Faraday constant n: Participates in the reaction Number of electrons E ⁰ _A1 : Standard redox potential of ^{An +} / A reaction system E ⁰ _C1 : Standard redox potential in conduction band of photocatalyst (b) When reductant A gives e ⁻ to valence band of photocatalyst ΔG ⁰ = −F · n · (E ⁰ _{C 2} −E ^{0 A} ₁ ) (8) E ⁰ _{C 2} : Standard oxidation-reduction potential in the valence band of the photocatalyst When pH is considered, E ⁰ _A1 and E ⁰ _C1, E ⁰ _C1 is corrected by calculating equation (6).

FIG. 8 illustrates a specific example of the ΔG ⁰ value calculation. Here, the case where the photocatalyst is titanium dioxide (TiO ₂ ) and the reaction system is NO ₃ ⁻ / NO ₂ ⁻ is described.

E ⁰ of the conduction band and the valence band of TiO ₂ at pH = 0 are −0.54 V and 2.66 V, respectively, and NO ₃ ⁻ /
NO ₂ ^- E ⁰ of the reaction system is 0.835V. Here, when electrons are received from the conduction band of TiO ₂ , the ΔG ⁰ value is a value obtained by subtracting the oxidation-reduction potential in the NO ₃ ⁻ / NO ₂ ⁻ reaction system from the oxidation-reduction potential of the conduction band of TiO _2. By multiplying the number of transferred electrons by the energy per electron −96.5 kJ / V / mol (Faraday constant), it is calculated as −265.38 kJ / mol (FIG. 8A). When electrons are given to the valence band of TiO ₂ , the ΔG ⁰ value is calculated from the oxidation-reduction potential of the valence band as NO ₃ ⁻ / NO ₂ ^−.
By multiplying the value obtained by subtracting the value of the oxidation-reduction potential of the reaction system from the number of transferred electrons and -96.485 kJ / V / mol,
It is calculated as −352.2 kJ / mol (FIG. 8 (b)).

As described above, the magnitude of ΔG ⁰ is an index indicating that the smaller the value, the easier the reaction proceeds in the direction of the reaction, but it does not necessarily mean that the reaction proceeds in that direction.

For example, even if the ΔG ⁰ value when receiving electrons from the conduction band is smaller than that when giving electrons to the valence band, the E ⁰ value is in a system that easily emits electrons (ie, ΔG 0). ^In the case where the direction of the reaction represented by the ⁰ value and the direction of the reaction represented by the E ⁰ value are opposite), the direction of the reaction represented by the E ⁰ value has priority, and in this case, the reaction proceeds in the direction in which electrons are emitted. Become.

FIG. 1 is a schematic diagram of an embodiment of an apparatus for performing a photocatalytic reaction prediction according to the present invention, and a flowchart of the photocatalytic reaction prediction using the apparatus.

As shown in FIG. 1, the photocatalytic reaction prediction device includes a pre-processing unit 1 and an arithmetic processing unit 2.

The apparatus further comprises recording means such as a hard disk and a memory, and the recording means
A database 11 for storing the reaction system and a photocatalyst (for example,
The database 12 storing the conduction band and valence band of the photocatalysts listed in FIG. 11 and the standard oxidation-reduction potential of the reaction system involving the sample substrate, and correction of the Nernst equation based on pH in the reaction system involving the sample substrate A database 13 for storing the number of terms and a database 21 for storing the number of mobile electrons for each reaction system involving the test substrate are freely recorded for reading and writing.

For this purpose, the photocatalytic reaction predicting apparatus is provided with input means, such as a keyboard and a mouse, and other pointing devices, and display means for monitoring input / output data, which are not shown in FIG. ,
Input / output display means or the like provided with a touch panel or the like having these functions may be provided.

The pretreatment means 1 receives a signal indicating the pH value of the reaction system from the outside, and a signal indicating the standard oxidation-reduction potential relating to the photocatalyst and the test substrate present in the reaction system from the database 12. The correction of the oxidation-reduction potential is performed from the value of the reduction potential by the calculation according to equation (6).

The arithmetic processing means 2 determines, based on the oxidation-reduction potential supplied from the pretreatment means 1, the state of promotion of inhibition of the oxidation-reduction reaction of the sample substrate caused by the photocatalyst.

The arithmetic processing means 2 determines the inhibition promotion status of the redox reaction of the test substrate caused by the photocatalyst, and obtains a reaction pathway of the test substrate which can occur by the photocatalyst. If so, determine whether an oxidation reaction or a reduction reaction will occur.

Further, when it is determined that the oxidation reaction and the reduction reaction caused by the photocatalyst proceed simultaneously, the arithmetic processing means 2 determines the number of mobile electrons supplied from the database 21 and the oxidation-reduction potential supplied from the preprocessing means 1. And from
The Gibbs free energy is calculated by the calculation according to equation (7) or (8), and based on the calculation result, which of the oxidation reaction and the reduction reaction occurs preferentially is determined.

Incidentally, the inhibition promotion status of the oxidation-reduction reaction obtained by the arithmetic processing means 2, the reaction path, the individual oxidation reaction and the reduction reaction, and the result of the oxidation reaction or reduction reaction determined to occur preferentially are as follows: It is stored in another database in the storage means and is retrieved as needed.

Here, the procedure for predicting the photocatalytic reaction according to the present invention when the photocatalyst is TiO ₂ , the substrate is ClO ₂ , and the solvent is water having a pH of 5 (steps 1 to 10 (hereinafter S1))
To S10)) will be described based on the flowchart of FIG.

First, by means of the input means, the solvent and the substrate
About "H_TwoO, O_Two, ClO_Two ^-(Or a key indicating them
Word) ”, photocatalyst“ TiO_Two(Or this
(S1a, S1b). This
At the time, the expected ClO_Two ^-Seki
Related reaction system “ClO_Three ^-/ ClO_Two ^-, ClO_Two ^-/ ClO^-, ClO^-/ Cl^-"But
And the solvent is water, the reaction system `` O_Two/ H
_Two"O" is obtained (S2). And database 12
Et al. Reported that E in the reaction system obtained in S2.⁰Value ("ClO _Three ^-/ C
lO_Two ^-(1.155V), ClO_Two ^-/ ClO^-(1.474V), ClO^-/ Cl^-(1.
228V) "(E in parenthesis⁰Value)) is acquired (S3
a) plus TiO_TwoConduction band E⁰Value (-0.54V) and valence electrons
Obi E⁰The value (2.66 V) is obtained (S3b). S3a and
The data acquired in S3b and⁰Value correction process
(S5a, S5b).

Next, a pH value, which is one of the reaction conditions, is input by the input means (S4). S3a and S3b
The E ⁰ value obtained in is the value when pH = 0. Then, a correction term (the second term of the operation formula (6)) corresponding to the input pH value and the obtained reaction system is extracted from the database 13 and is used for correcting the E ⁰ value (S5a, S5
b). The data calculated in S5a and S5b is provided to the next operation processing step (S6 to S10).

In step S6, the data obtained in steps S5a and S5b are arranged in the order of potential, and the order of priority of the reaction and the inhibition of the reaction are determined.
Predict the promotion situation. Here, E ⁰ _{pH = 5} means that TiO ₂ conduction band (−0.836 V) <ClO ₃ ⁻ / ClO ₂ ⁻ (0.860 V) <O ₂ / H ₂ O (0.
^{_{933V) <ClO 2 - / ClO}} - (1.179V) <ClO - / Cl - (1.420V)
<TiO ₂ valence band (2.365V), and the result is disclosed by the display means in a form as shown in Table 7 (however, in the same table, excluding I-type, N-type and Br-type), The prediction is performed. That is, the ClO ₂ ⁻ / ClO ⁻ system is judged to be a system in which the E ⁰ _{pH = 5} value is larger than the reference value (0.933 V) and thus it is easy to take in electrons, in other words, a system in which the reduction reaction easily proceeds. You.

Since no coexisting substance with the sample substrate ClO ₂ is present in the reaction system, no prediction of the reaction inhibition / promotion state is performed.

At S7, a reaction route is predicted from the result at S6. This determines the presence or absence of a reaction, or if a reaction occurs, whether it is an oxidation reaction or a reduction reaction. In the reaction system, a reaction route consisting of the following oxidation-reduction reaction is obtained, for example, in the form of a Cl system shown in Table 2 (however, in the same table, except for I system, N system and Br system), It is disclosed by the display means.

ClO ₃ ⁻ ← ClO ₂ ⁻ → ClO ⁻ → Cl ^{− In} each of the substances in which the oxidation reaction and the reduction reaction proceed simultaneously, the superiority of the oxidation reaction and the reduction reaction is predicted (S9, S10). For that purpose, in S8, each of the substances in the above-mentioned reaction path obtained in S7 is first selected. Here, the reaction pathway top left side of the material, ClO ₃ ^- is selected.

At S9, it is confirmed whether the oxidation reaction and the reduction reaction of the substance selected at S8 proceed simultaneously. If the process proceeds simultaneously, the process proceeds to S10. If no reaction occurs or only one reaction occurs, the process ends, the process returns to S8, and the substance on the right is selected.
The confirmation work is performed. In other words, ClO ₃ ^- In the case of,
It is determined that neither an oxidation reaction nor a reduction reaction occurs, and the process directly proceeds to S8, where ClO ₂ ^- is selected. ClO ₂ ^- For believed to reduction reaction with the oxidation reaction occurs.
So, to determine which reaction is dominant,
It is provided to the arithmetic processing of S10.

At S10, which of the oxidation reaction and the reduction reaction in the reaction system supplied from S9 (here, the reaction system using ClO ₂ ^- as the substrate) predominates is determined by calculation. . That is, the ClO ₃ obtained in S6
^- / ClO ₂ ^- systems and ClO ₂ ^- and system E ⁰ values, ClO ₃ drawn from the database _{^{21 - - / ClO / ClO 2}} - systems and ClO ₂ ^over / ClO ^- from system moving electron number and the arithmetic According to the equations (7) and (8), ClO ₃ ⁻ / ClO ₂
^- systems and ClO ₂ ^- / ClO ^- system calculates the G ⁰ of. G ⁰ = −388.7 (kJ / mol) when ClO ₂ ⁻ receives electrons from the conduction band, and G ⁰ = −290.5 (kJ / mo) when ClO ₂ ⁻ supplies electrons to the valence band.
l) Therefore, it is predicted that the reaction of receiving electrons from the conduction band, that is, the reduction reaction (ClO ₂ ⁻ → ClO ⁻ ) will proceed predominantly. The reaction prediction result is externally output by the output display means and disclosed. Further, other materials (ClO here ^-, Cl ^-) for also, in the same way as this, S
9, reaction prediction is executed via S10. However, ClO ^-
The reduction reaction, Cl ^- since the reaction does not proceed for not migrated from S9 to S10.

Next, prediction of the state of promoting the inhibition of the oxidation-reduction reaction according to the present invention when two types of substrates are present in a certain reaction system will be described. Here, the solvent is water and pH = 5
Referring to FIG. 1, the case where it is desired to perform a reduction treatment of BrO ⁻ in an environment where ClO ⁻ and NO ₂ ⁻ coexist in the reaction system will be described.

Description will be made of a case where coexist ^- [0084] ClO.

According to the input means, “H ₂ O, O ₂ , BrO ⁻ , ClO ₂ ⁻ (or a keyword indicating these)” for the solvent and the substrate, and “TiO ₂ (or a keyword indicating this)” for the photocatalyst Input (S1a, S1b). Then, in the same manner as described above, through S2 to S5, H ₂ O,
The E ⁰ value of the reaction system involving O ₂ , BrO ⁻ and ClO ₂ ⁻ is corrected. The corrected E ⁰ value is provided to S6.

S6 is performed in S5a and S5b as before.
The obtained data is arranged in order of potential, and the priority of the reaction and
Predict reaction inhibition / promotion status. Here, E⁰ _{pH = 5}
Is TiO_TwoConduction band (-0.836V) <ClO_Three ^-/ ClO_Two ^-(0.860V)
<O_Two/ H_TwoO (0.933V) <BrO_Three ^-/ BrO^-(1.046V) <ClO_Two ^-/ C
lO^-(1.179V) <BrO^-/ Br^-(1.294V) <ClO^-/ Cl^-(1.4
20V) <TiO_TwoOrdered with the valence band (2.365V), resulting in
Is displayed by the display means, for example, as shown in Table 7 (however,
In the same table, I and N systems are excluded)
Measurement is performed. That is, TiO_TwoConduction band E⁰ _{pH = 5}value
And the conduction band E⁰ _{pH = 5}Value and BrO_Three ^-/ BrO^-System E⁰
_{pH = 5}Value difference and conduction band E⁰ _{pH = 5}Value and ClO ^-/ Cl^-System E⁰
_{pH = 5}Considering the difference in the values, the likelihood of the reduction reaction
(ClO^-→ Cl ^-)> (BrO^-→ Br^-). This allows Cl
O^-Is determined to occur preferentially, and ClO^-By
BrO^-Is predicted to be reduced. This reaction
The measurement results are output externally by the output display means and disclosed.
Is done.

Description will be made of a case where coexist ^- [0087] NO _2.

According to the input means, “H ₂ O, O ₂ , BrO ⁻ , NO ₂ ⁻ (or a keyword indicating these)” for the solvent and the substrate, and “TiO ₂ (or a keyword indicating this)” for the photocatalyst. Input (S1a, S1b). Then, in the same manner as described above, through S2 to S5, H ₂ O,
The E ⁰ value of the reaction system involving O ₂ , BrO ⁻ and NO ₂ ⁻ is corrected. The corrected E ⁰ value is provided to S6.

In step S6, similarly to the above, the data obtained in steps S5a and S5b are arranged in the order of potential, and the priority of the reaction and the inhibition / promotion state of the reaction are predicted. Here, E ⁰ _{pH = 5}
Is, TiO ₂ conduction band ^{_{(-0.836V) <NO 3 - /}} NO 2 - (0.540V) <
_{^{NO 2 - /NO(0.611V)<O 2 / H 2}} O (0.933V) <BrO 3 - / BrO
^- by (1.294V) <is TiO ₂ valence band and (2.365V) Seijo, the result display ^{means, - (1.046V) <BrO -} / Br
For example, the prediction is disclosed in the form as shown in Table 7 (however, in the same table, excluding I-based and Br-based), and the prediction is performed.
That is, the E ⁰ _{pH = 5} values of NO ₃ ⁻ / NO ₂ ⁻ and BrO ⁻ / Br ⁻ are compared in the same manner as described above, and NO ₃ ⁻ / NO ₂ ⁻ is a system in which an oxidation reaction occurs, BrO − ^- / Br ^- is judged to be a system in which a reduction reaction occurs, and NO
₂ ^- BrO by oxidation of ^- reduction treatment is expected to be promoted. The reaction prediction result is externally output by the output display means and disclosed.

The photocatalytic reaction predicting apparatus according to the present invention comprises:
It is not limited to the device configuration disclosed in FIG. For example, if the steps shown in FIG. 1 are programmed to be executed by a computer and stored in a computer-readable recording medium, the functions of the photocatalytic reaction prediction apparatus according to the present invention can be executed by a calculating means such as a personal computer. Becomes possible.

The operation and effect of the present invention will be described based on the following embodiments. (First and Second Embodiments) Prediction of Photocatalytic Reaction in Liquid Phase System This embodiment assumes a photocatalytic reaction when the photocatalyst is titanium dioxide (TiO ₂ ) and the solvent is water (H ₂ O). The substances in question are used as test substrates. Here, Br
System, Cl-based, I-based and N-based compounds have been tested.

As described above, the photocatalytic reaction predicting means according to this embodiment assumes that the photocatalytic reaction when the solvent is water is E ⁰ ( ^{O 0} ) between oxygen (DO) dissolved in water and water. O
₂ / H ₂ O) is used as a reference potential, and an oxidation-reduction reaction is predicted according to the flowchart of FIG.

Table 1 shows that the test substrates were Br-based, Cl-based, I-based and N-based.
It is a list of E ⁰ value and G ⁰ calculated value when it is a compound of the system,
Table 2 shows the results of prediction of the oxidation-reduction reaction of the test substrate.

[0094]

[Table 1]

[0095]

[Table 2]

[0096] 1) Reaction prediction BrO when the Br compound was trial substrate ₃ ^- / BrO ^- system and BrO ^- / Br ^- system, E ⁰ value reference value (O ₂ / H ₂ O system E ⁰ Value), it is determined that a reduction reaction is likely to occur because the system easily takes in electrons (Table 1). Therefore, a reduction reaction of BrO ₃ ⁻ → BrO ⁻ progresses in the conduction band, and an oxidation reaction of H ₂ O → O ₂ progresses in the valence band. Also, the BrO ⁻ generated in the conduction band has an E ⁰ value of BrO ⁻ / Br based on BrO ⁻
₃ ^- / BrO ^- system is larger than E ⁰ values, BrO ₃ ^- → BrO ^- reaction above BrO ^- → Br ^- reaction easily proceeds in. Therefore, BrO ₃ ^- is, BrO ^- without accumulating, Br ^- is expected to be reduced to (Table 2). In the case of Table 1, ClO ₃ ^{- -} Reaction prediction i) ClO ₃ when the 2) Cl compound was trial substrate / ClO ₂ ^- system is likely systems emit electrons lower than the reference value E ⁰ value It is. Therefore, the direction of the reaction is ClO ₂ ⁻ → ClO ₃ ⁻ (Table 2). Thus, ClO ₃ ^- is expected to the change is not observed.

[0097] ii) ClO ₂ ^- First case, in Table 1, ClO ₂ ^- / ClO ^- The system is a write easily based preparative electron larger than the reference value E ⁰ values,
Therefore, the reduction reaction easily proceeds.

Therefore, in the conduction band, the reaction of ClO ₂ ⁻ → ClO ⁻ is expected to proceed (Table 2). Where the generated Cl
O ^- is, ClO ^- / Cl ^- system E ⁰ value ClO ₂ in ^- / ClO ^- based E ⁰ values that from (Table 1) larger than the, ClO ₂ ^- → ClO ^- ClO the reaction above ^-
→ Cl ^- reaction easily proceeds in, ClO ^- C without accumulates
l ^- that expected to be reduced (Table 2).

At this time, the reaction of the valence band is ClO ₃ ⁻ / ClO ₂
^- based E ⁰ values from less than the reference value (Table 1), the valence band ClO ₂ ^- → ClO ₃ ^- reaction proceeds (Table 2). At this time, the generated ClO ₃ ^- is predicted to accumulate because the reaction does not proceed any more from the above item i) (Table 2). 3) Reaction prediction i when the I compound was trial substrate) IO ₃ ^- if IO ₅ ^3- / IO ₃ ^- system, IO ₄ ^- / IO ₃ ^- Since E ⁰ values for both systems is larger than the reference value (Table 1), the reaction of orientation ^{_{IO 5 3- → IO 3 -,}} IO 4 -
→ IO ₃ ^- and a is expected (Table 2).

In the IO ₃ ⁻ / IO ⁻ system, since the E ⁰ value is smaller than the reference value (Table 1), the reaction direction is predicted to be IO ⁻ → IO ₃ ⁻ (Table 2).

From the above, it is expected that an oxidation-reduction reaction using IO ₃ ^- as a raw material will not occur.

Ii) I^-In Table 1, I^-/ I_Three ^-System E⁰Value is less than reference value
(In this system, there is no electron transfer in the reaction formula,
Is calculated as 0). Therefore, in the valence band, I^-
→ I_Three ^-Is expected to proceed (Table 2). here,
Generated I_Three ^-Is I_Two/ I_Three ^ーSystem E⁰Value is I^-/ I_Three ^-System E⁰value
Is greater than_Three ^-I than the consumption speed of_Three ^-Generate
Since the speed is faster, I_Three ^-Accumulation of
But ultimately I_TwoIs expected to be oxidized to
2). 4) Reaction prediction when N-based compound is used as test substrate i) NO_Three ^-In Table 1, NO_Three ^-/ NO_Two ^-System E⁰Value is less than reference value
Therefore, an oxidation reaction is likely to occur. Therefore, the reaction
Direction is NO_Two ^-→ NO_Three ^-Becomes From this, NO _Three ^-Ancestry
Is not expected to proceed (Table 2).

[0103] ii) NO ₂ ^- if NO ₃ of ^- / NO ₂ ^- Reaction of orientation as described in i) for systems, NO ₂ ^- → NO ₃ ^- become. Further, since the NO ₂ ⁻ / NO system is a system in which the E ⁰ value is smaller than the reference value and easily emits electrons, the reaction direction is NO → NO ₂ ⁻ (Table 2).

Table 3 shows that the Br system, Cl obtained in the actual load test,
These are the reaction pathways of the system, I system and N system compounds, which are consistent with the reaction prediction (Table 2).

[0105]

[Table 3]

As is clear from the results in Table 3, when a photocatalyst (TiO ₂ ) is used in a liquid phase system composed of water, a comparison of the E ⁰ values of the substances contained in the liquid phase and the calculation of the G ⁰ value give The oxidation-reduction reaction caused by the photocatalyst can be predicted.

[0107] Further, FIG. 9, ClO ₂ ^- Cl produced by reduction and oxidation of the ^- and ClO ₃ ^- is a characteristic diagram showing changes over time in the concentration of.

[0108] As shown in FIG. 9, ClO ₂ ^- when containing, ClO ₂ ^- ClO ₂ to the original system ^{_{- → Cl -, ClO 2 -}} → ClO 3 - although two reactions proceed in , energetically ClO ₂ ^- → ClO ^- → C
l ^- towards the reaction for easy progress of (G ⁰ values in Table 1), the reduction reaction has been shown to proceed preferentially.

The method for predicting a photocatalytic reaction according to the present invention enables prediction of an oxidation-reduction reaction caused by a photocatalyst even in a solvent other than water (second embodiment).

When the solvent is water (first embodiment), O ₂ / H ₂ O
The E ⁰ value of the system was used as a reference potential, and a reduction reaction or an oxidation reaction was predicted by comparing this value with the E ⁰ value of the target reaction system.

The prediction of the photocatalytic reaction in a solvent other than water is as follows:
As in the first embodiment, the E ⁰ value of the reaction system of the solvent itself is used as the reference potential. Then, based on the flow sheet of FIG. 1, the reference potential and E ⁰ of the sample substrate are compared to predict the oxidation-reduction reaction route of the sample substrate. (Third Embodiment) Prediction of Redox Reaction Occurred by Photocatalysts Other Titanium Dioxide In the first and second embodiments, titanium dioxide (TiO ₂ ) is taken up, but the photocatalyst prediction method according to the present invention is performed by other photocatalysts. It is also possible to predict oxidation-reduction reactions.

FIG. 11 shows a typical photocatalyst and its energy diagram (pH = 0).

The photocatalysts in the figure are listed by way of example, and the photocatalysts obtained by appropriately combining these, for example, titanium dioxide may be blended as a base. For such a photocatalyst, the oxidation-reduction potential (E ⁰ ) of the conduction band and the valence band is checked in advance, and stored in the database 12 of the photocatalytic reaction prediction device according to the present invention.

Here, the effect of predicting the photocatalytic reaction according to the present invention when zinc oxide (ZnO) is used as the photocatalyst, water is used as the solvent, and Br, Cl and N compounds are used as the test substrates are shown.

Table 4 lists the conduction band and valence band of ZnO, the E ⁰ value of the test substrate, and the G ⁰ calculated value of the test substrate. Table 5 shows the photocatalytic reaction prediction method according to the present embodiment. 4 is a prediction of a redox reaction pathway of each sample substrate obtained by the above method.

Table 6 shows the redox reaction pathways of Br-based, Cl-based and N-based compounds obtained by the actual load test.

[0117]

[Table 4]

[0118]

[Table 5]

[0119]

[Table 6]

As is clear from the results shown in Table 6, even when a photocatalyst other than TiO ₂ is used, the reaction of the photocatalyst treatment in all the solvents including water becomes possible as in the first and second embodiments. (Fourth Embodiment) Prediction of Photocatalytic Reaction in Liquid Phase System Considering pH Here, the pH of the reaction system is 5, the sample photocatalyst is TiO ₂ and ZnO, and the sample substrate is the same Br-based, Cl In the case of a system, an I system, and an N system compound, the oxidation-reduction reaction route is predicted based on the flow sheet of FIG.

Table 7 is a list of the conduction band and the valence band when the photocatalyst is TiO ₂ , and the E ⁰ value and the G ⁰ calculated value of the sample substrate. Table 8 is a list of the conduction band and the valence band when the photocatalyst is ZnO, and the E ⁰ value and the G ⁰ calculated value of the sample substrate. Incidentally, according to Table 1 and Table 7, I ^- / I ₃ ^- system and
I ₂ / I ₃ ^- system E ⁰ value is not affected by pH, I ^- and I
₂ does not contain oxygen, as is evident from its structural formula. Here, the photocatalytic reaction prediction according to the present invention interprets that hydrogen ions do not participate in the I ⁻ / I ₃ ⁻ reaction system and the I ₂ / I ₃ ⁻ reaction system, and in the following arithmetic expression (6), m = 0 The arithmetic processing is performed as follows. Therefore, the E ⁰ value was not corrected.

[0122]

[Table 7]

[0123]

[Table 8]

The oxidation-reduction reaction prediction showed the same prediction results as Tables 2 and 5 of the first and third embodiments, but Tables 3 and 6 of the same embodiment were also obtained by the actual load test. The same oxidation-reduction reaction pathway as in Example 1 was obtained. This indicates that the photocatalytic reaction prediction method according to the present invention can predict the photocatalytic reaction even when the pH of the reaction system changes. (Fifth Embodiment) Photocatalytic Reaction Prediction in Gas Phase System In the first and second embodiments, the application effect of a photocatalyst in a liquid phase system has been described using TiO ₂ as an example. The method and apparatus for predicting a photocatalytic reaction according to the present invention can predict various oxidation-reduction reactions caused by the photocatalyst in consideration of the ease of electron transfer with the photocatalyst and the free energy at that time.

FIG. 10 is a schematic diagram of a photocatalytic reaction in the atmosphere.

The method and apparatus for predicting a photocatalytic reaction according to the present embodiment can be used not only when water droplets adhere to the photocatalyst surface due to the effects of high humidity and rainfall, but also when the water droplets visually adhere to the photocatalytic surface. However, it is considered that the solvent is water because the photocatalyst surface is microscopically wet by water molecules present in the atmosphere.

Therefore, as in the first embodiment, O ₂ / H
_Using the standard oxidation-reduction potential (E ⁰ value) of the ₂ O system as a reference potential,
The G value of the reaction system for the test substrate is determined according to the procedure of the flow sheet in FIG. 1 to predict the oxidation-reduction reaction caused by the photocatalyst.

At this time, the pH is considered to be neutral (pH = 7), and the E ⁰ value is corrected based on the fourth embodiment to calculate G ⁰ .

Table 9 shows the E for some substances (in the present embodiment, formaldehyde, carbon dioxide, methane, and nitric oxide) that are of concern in the atmospheric environment.
It is a list of ⁰ values and G ⁰ values, and Table 10 shows the prediction of the oxidation-reduction reaction pathway of the test substrate obtained by the photocatalytic reaction prediction method according to the present invention.

[0130]

[Table 9]

[0131]

[Table 10]

Table 11 shows the reaction routes obtained by the actual load test.

[0133]

[Table 11]

The results show that the photocatalytic reaction prediction method according to the present invention can be applied to a gas phase system (atmosphere). (Sixth and Seventh Embodiments) Photocatalytic Reaction Prediction in a Gas Phase System without Water Molecules The photocatalytic reaction prediction method and apparatus according to the present invention can also be applied to a gas phase system without water molecules. is there.

[0135] At this time, similarly to the second embodiment obtains the E ⁰ values of the reaction system involving the substance present in the vapor phase system, compares these, valence smaller reaction system of E ⁰ value It is considered that the oxidation reaction occurs in the band and the reaction system having the larger E ⁰ value causes the reduction reaction in the conduction band. At this time, the calculated E ⁰ value is corrected in the same manner as in the fourth embodiment according to the pH of the system.

In the fifth and sixth embodiments, TiO ₂ has been described as an example of a photocatalyst. However, similar effects can be obtained for other photocatalysts as in the third embodiment (seventh embodiment). .

[0137]

As is clear from the above description, according to the photocatalytic reaction prediction method, the apparatus, the program and the medium according to the present invention, all the photocatalytic reactions can be predicted.

Further, when considering photocatalytic treatment, a photocatalytic reaction can be predicted. Therefore, if a substance existing in a gas phase environment or a liquid phase environment to be treated is known, it is determined whether or not the application of the photocatalytic treatment is effective. It can be easily predicted.

Further, it can be easily predicted whether the decomposition reaction of the substance to be treated is promoted or inhibited by the coexisting substance. Therefore, when designing the photocatalyst treatment apparatus, the labor required for experiments and the labor required for complicated calculations in predicting the reaction are greatly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an embodiment of a photocatalytic reaction prediction device according to the present invention and a flowchart of photocatalytic reaction prediction by the embodiment.

FIG. 2 (a) is a schematic diagram of electrical excitation by a photocatalytic reaction,
(B) BrO is with ozone ₃ ^- schematic representation of a production path,
(C) is a schematic explanatory diagram of a denitrification route.

[Figure 3] NO ₃ -N in the photocatalyst treatment, in time course of NO ₂ -N concentration, (a) shows the case of NO ₃ ^over sole system, (b) in the case of NO ₂ ^over a single system.

FIG. 4 is an explanatory diagram of how to view an oxidation-reduction potential in a photocatalytic reaction when a solvent is water.

[5] NO ₂ ^- in the case of not a case where a coexists BrO ₃ ^-
Concentration behavior.

[6] ClO ₂ ^- in the case of not a case where a coexists BrO ₃ ^-
Concentration behavior.

FIG. 7: Redox potential (E ⁰ value (V)) of main reaction system (pH
= 0).

FIG. 8 is an explanatory diagram of a calculation method of ΔG ⁰ (here, NO ₃ ⁻ / NO
₂ ^- system), where (a) receives electrons from the conduction band,
(B) is a case where electrons are given to the valence band.

[9] ClO ₂ ^- Cl produced by reduction and oxidation ^-, Cl
O ₃ ^- concentration time course of.

FIG. 10 is a schematic diagram of a photocatalytic reaction in the atmosphere.

FIG. 11 is an energy diagram (pH = 0) of a typical photocatalyst.

[Explanation of symbols]

 1 ... Preprocessing means 2 ... Operation processing means 11,12,13,21 ... Database

Continued on the front page (72) Inventor Yoshihiko Tagawa 2-1-117 Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd. (72) Inventor Shigeo Sato 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd. F term (reference) 4D048 AA06 AA13 AA19 AA30 BA07X BA16X BA41X EA01 4G069 AA02 AA03 AA20 BA04B BB04B BC35B CA02 CA05 CA13 CA15 CA17 CA20 DA05 4G075 AA15 AA67 BA04 BA06

Claims (12)

[Claims] 1. A method for predicting a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present, comprising: a conduction band and a valence band of the photocatalyst based on a pH value of a system in which the photocatalyst and the test substrate are reacted. And correcting the standard oxidation-reduction potential of the reaction system relating to the substrate, adjusting the corrected oxidation-reduction potential in the order of the potential, and adjusting the oxidation-reduction potential to obtain a test substrate generated by the photocatalyst. Determining the state of promoting inhibition of the oxidation reaction or reduction reaction of the photocatalyst. 2. After arranging the corrected oxidation-reduction potential in the order of potential, obtaining a reaction path of a sample substrate which can occur by the photocatalyst, and determining whether or not a reaction of the sample substrate caused by the photocatalyst occurs, or The method for predicting a photocatalytic reaction according to claim 1, further comprising a step of determining whether to determine whether the reaction is an oxidation reaction or a reduction reaction. 3. A step of selecting one of the substance names in the obtained reaction path, a step of judging whether or not an oxidation reaction and a reduction reaction proceed simultaneously with respect to this substance; When proceeding simultaneously, the Gibbs free energy of the oxidation reaction and the reduction reaction is calculated by calculation from the corrected oxidation-reduction potential, and based on the calculation result, which of the oxidation reaction and the reduction reaction has priority. 3. The method for predicting a photocatalytic reaction according to claim 2, further comprising a step of determining whether the photocatalytic reaction occurs. 4. An apparatus for predicting a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present, comprising: input means for inputting a photocatalyst name, a test substrate name, and a pH value of the reaction system;
In advance, recording means for recording the standard oxidation-reduction potential of the reaction system involving the conduction band and valence band of the photocatalyst and the sample substrate, the pH value of the reaction system, and the photocatalyst present in the reaction system from the recording means and A standard oxidation-reduction potential value relating to the sample substrate is supplied, a pre-processing means for correcting the oxidation-reduction potential by calculation from these values, and an oxidation-reduction potential corrected by the pre-processing means are supplied. An arithmetic processing means for determining, based on the value of the reduction potential, the inhibition promotion state of the oxidation or reduction reaction of the sample substrate caused by the photocatalyst; and the inhibition promotion state of the oxidation reaction or reduction reaction of the sample substrate determined by the arithmetic processing means Means for outputting a reaction prediction result as a reaction prediction result. 5. The arithmetic processing means obtains a reaction path of a sample substrate that can occur by a photocatalyst based on the value of the oxidation-reduction potential supplied from the preprocessing means, and determines whether or not a reaction is present or not by a calculation. 5. The photocatalytic reaction predicting device according to claim 4, wherein if it occurs, it is determined whether the reaction is an oxidation reaction or a reduction reaction. 6. The arithmetic processing means, when judging that the oxidation reaction and the reduction reaction proceed simultaneously in each of the substances in the obtained reaction path, by calculating from the value of the oxidation-reduction potential supplied from the preprocessing means. The photocatalytic reaction prediction device according to claim 5, wherein a Gibbs free energy is calculated, and which of the oxidation reaction and the reduction reaction occurs preferentially is determined based on a result of the calculation. . 7. A computer for predicting a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present.
Input means for inputting a photocatalyst name, a sample substrate name, and a pH value of a reaction system, and recording means for recording in advance the conduction and valence bands of the photocatalyst and the standard oxidation-reduction potential of the reaction system involving the sample substrate. , The pH value of the reaction system, and the standard oxidation-reduction potential value relating to the photocatalyst and the test substrate present in the reaction system are supplied from the recording means, and the pre-processing for correcting the oxidation-reduction potential by calculation from these values is performed. Means, an oxidation-reduction potential corrected by the pre-processing means is supplied, and based on the value of the oxidation-reduction potential, arithmetic processing means for determining the inhibition promotion state of the oxidation or reduction reaction of the test substrate caused by the photocatalyst, Photocatalytic reaction prediction for functioning as a means for outputting, as a reaction prediction result, the inhibition promotion status of the oxidation or reduction reaction of the test substrate determined by the arithmetic processing means Program. 8. The arithmetic processing means obtains a reaction path of a sample substrate which can occur by a photocatalyst based on the value of the oxidation-reduction potential supplied from the preprocessing means, and determines whether or not a reaction has occurred, The photocatalytic reaction prediction program according to claim 7, wherein if it occurs, it is determined whether the reaction is an oxidation reaction or a reduction reaction. 9. The arithmetic processing means, when judging that the oxidation reaction and the reduction reaction proceed simultaneously in each of the substances in the obtained reaction path, by calculation from the value of the oxidation-reduction potential supplied from the preprocessing means. 9. The photocatalytic reaction prediction program according to claim 8, wherein a Gibbs free energy is calculated, and which of the oxidation reaction and the reduction reaction occurs preferentially is determined based on a result of the calculation. . 10. In order to predict a photocatalytic reaction in a reaction system in which a photocatalyst and a test substrate are present, a computer is provided with input means for inputting a photocatalyst name, a test substrate name, and a pH value of the reaction system; Recording means for recording the standard oxidation-reduction potential of the reaction system involving the conduction band and valence band of the reaction substrate, and the pH value of the reaction system, and the photocatalyst and the test substrate present in the reaction system from the recording means. And a pre-processing means for correcting the oxidation-reduction potential by calculation from these values, and an oxidation-reduction potential corrected by the pre-processing means are supplied. Arithmetic processing means for determining, based on the value, inhibition promotion of the oxidation or reduction reaction of the test substrate caused by the photocatalyst; and the oxidation reaction of the test substrate determined by the arithmetic processing means. Computer readable recording medium recording a photocatalytic reaction prediction programs for the properly function as a means for outputting the inhibition promoting conditions of the reduction reaction as a reaction prediction result. 11. The arithmetic processing means obtains a reaction path of a sample substrate that can occur by a photocatalyst based on the value of the oxidation-reduction potential supplied from the preprocessing means, and determines whether or not a reaction is present or not by a calculation. 11. The method according to claim 10, further comprising determining whether the reaction is an oxidation reaction or a reduction reaction.
A computer-readable recording medium on which the photocatalytic reaction prediction program described above is recorded. 12. The arithmetic processing means, when judging that the oxidation reaction and the reduction reaction proceed simultaneously in each of the substances in the obtained reaction path, performs an arithmetic operation from the value of the oxidation-reduction potential supplied from the preprocessing means. The photocatalytic reaction prediction program according to claim 11, wherein a Gibbs free energy is calculated, and which of the oxidation reaction and the reduction reaction occurs preferentially is determined based on the calculation result. A computer-readable recording medium on which is recorded.