JPH1179725A - Method for electrochemical fixing carbon dioxide by using phthalocyanine complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and catalytically fix carbon dioxide under soft conditions such as at room temp. and atmospheric pressure by using an electrochemically activated phthalocyanine complex to allow carbon dioxide to react with oxirane. SOLUTION: The catalyst used consists of a planer or sandwich-like deriv. of t-butyl substd. phthalocyanine complex, namely, it contains t- butylphthalocyanine complex of nonmetal, bivalent metal, tervalent metal or quadrivalent rare earth element. As for the bivalent metal, Co<2+> , Cu<2+> , Zn<2+> , etc., are used. As for tervalent metals, Rh<3+> , Eu<3+> , Dy<3+> ,Tr<3+> , Al<3+> , etc., are used. The rare earth elements are Pr, Tb, Dy, etc. For example, tetra-t- butylphthalocyanine, tetra-e-butyl substd.-mono or diphthalocyanine of transition elements or rare earth elements, or reduced phthalocyanine compd. are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a catalyst,
The present invention relates to a method for fixing carbon dioxide using an olefin oxide (oxirane). In the present invention, pl
The catalyst used is an anar-type or sandwich-type transition element or a rare earth element, or a metal-free tetra-3-butylphthalocyanine complex electrochemically reduced to a mono- and dianine-type. The reaction which is the object of the invention can be carried out under a soft condition (atmospheric pressure, atmospheric pressure, phthalocyanine complex solution) or a heterogeneous catalyst (a phthalocyanine complex coated on a solid support such as graphite). Room temperature).

[0002]

2. Description of the Related Art In today's world, where the burden of human society on the biosphere is increasing rapidly and the consumption of mineral fuels is increasing, the increase in the concentration of carbon dioxide in the atmosphere is approaching its limit and becoming dangerous. I have. One way to solve this problem is to develop a technology that uses atmospheric carbon dioxide as a cheap and ubiquitous carbon source for organic fine chemical synthesis. Carbon dioxide can be activated mainly by three methods: a catalytic method, a photochemical method, and an electrochemical method. However, this classification is rather expedient and is usually most practical in practice when using photochemical or electrochemical methods in the presence of metal complexes.

A known electrochemical reaction for fixing carbon dioxide is to form CO, CH ₄ and HCOOH using an aqueous solution of a phthalocyanine complex of a transition metal (N. Furya, S. Kode, Electrochimica Acta, 1991,
vol.36, p1309). However, in order to realize this process, a high potential of at least -1.5 V with respect to the saturated calomel electrode has to be applied to the cathode, so that the possibility of this method is limited. .
Under such high potential conditions, accompanying reactions such as reduction of the reagent added to the solution as a trap for fixing carbon dioxide may occur, and the product may easily return to carbon dioxide. (Oxidation by air oxygen, heating, etc.).

As a more promising method, carbon dioxide is
Some convert to "green" polymers, isolating them from the atmospheric circulation for extended periods of time. Among them, the one closest to the present invention is one in which carbon dioxide is reacted with oxirane using a metal complex as a catalyst to obtain alkylene carbonate (US Pat. No. 5,283,35).
6) However, this method is only possible under hard conditions (high temperature, high pressure carbon dioxide), and the catalyst is hard to melt, possibly resulting in a heterogeneous reaction environment and a corresponding decrease in the effect. There are defects.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for efficiently and catalytically fixing carbon dioxide under soft conditions such as room temperature and atmospheric pressure.

[0006]

In order to solve the above-mentioned problems, the present invention uses an electrochemically activated phthalocyanine complex as a catalyst, and converts carbon dioxide into oxirane in the presence of a catalyst. A method for reacting and fixing is provided.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The deficiency of the process of the above-mentioned U.S. patent which combines carbon dioxide with an olefin oxide to form an alkylene carbonate ring is, according to the present invention, a metal-free tetra-
The problem can be solved by using a reduced form of the phthalocyanine compound as a catalyst for the process, such as tert-butyl phthalocyanine, a tetra-3-butyl-substituted mono- or diphthalocyanine of a transition element or a rare earth element.

[0008]

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[0009] (wherein, R represents hydrogen or tert- butyl group, and X is Cl ^-. Represents a) formula I above represents a metal-free phthalocyanine, II represents a phthalocyanine comprising a divalent metal, III is Shows phthalocyanines containing trivalent metals and IV stands for the rare earth element diphthalocyanine. The former three are planer types, and IV is a sandwich type. Co as a divalent metal
²⁺ , Cu ²⁺ , Zn ^{2+ and the} like.
h ³⁺ , Ru ³⁺ , Dy ³⁺ , Pr ³⁺ , Al ^{3+ and the} like.
Examples of the rare earth element include Pr, Tb, and Dy. The complex used as a catalyst is activated by reversibly electrochemically reducing it (one or two electron reduction) (active catalyst). At that time, the complex becomes a mono- or dianine-type catalyst depending on the number of electrons. .

The fixation of carbon dioxide is carried out according to the following scheme.

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As a model compound to which carbon dioxide is fixed, for example, propylene oxide and epichlorohydrin are used. The structure of the reaction product is already established by spectroscopic and mass spectral data. In the reaction system, a catalyst cycle occurs according to the reaction conditions and the nature of the catalyst, and the number is determined by a calibration curve method. In this method, a product concentration in a solution is obtained by an infrared spectrometer.

To carry out the reaction, the anode and the cathode are separated.
Any shape electricity with carbon dioxide inlet
Chemical cells are suitable. The electrodes are, for example, platinum or
It is made of graphite. Activation of the catalyst depends on the static potential
Under electrode conditions (controlling the electrode potential)
You. The action of the catalyst is the first step in the reduction of the phthalocyanine complex.
But it can also be obtained in the second stage, but usually the second stage
High yield of alkylene oxide. In this reaction, the catalyst
Homo (homogeneous) or hetero (heterogeneous)
It is possible. In the case of a homocatalyst, the catalyst,
The reduced form of the cyanine complex is CH _ThreeSimple liquid of CN or CH
_ThreeCN: CH_TwoCl_Two= Dissolved in a 4: 1 mixture
Is used in the presence of large amounts of epoxide.

[0013] The graphite coated with several small holes and coated with a catalyst is used as an electrode, which is used as BU ₄ NBF ₄
The effect of the process can be enhanced by immersing it in a CH ₂ CN solution containing 0.02 mol and epoxide and supplying carbon dioxide through this electrode. In this case, the yield of the reaction product largely depends on the structure and porosity of the graphite. Since the catalyst is not consumed or decomposed during the reaction process, the number of catalyst cycles per mole of catalyst (and thus also the yield of reaction products) increases as the reaction time increases.

Although the present invention relates to a method for fixing carbon dioxide using an electrochemically activated catalyst, this method has several advantages. First, carbon dioxide is converted to the usual electrocatalytic reduction products (C
O, CH ₄ , HCOOH) and could not be obtained under soft conditions. It can be converted to a valuable organic substance, alkylene carbonate. Second, particularly in the case of diphthalocyanine, the potential required for the reaction is very low (-0.1 to -0.2 V with respect to the saturated calomel electrode). This process is not a carbon dioxide reduction process, but a chemical reaction between carbon dioxide and an epoxide under the influence of a mono-reduced diphthalocyanine catalyst. The electrochemical reduction of diphthalocyanine, which is a catalyst, can be performed very easily, so that there is no accompanying reaction such as electroreduction of other electroactive compounds present in the solution, and therefore, the selectivity of the process should be high. Can be.

The present invention seeks to develop a method of electrochemically activating a phthalocyanine complex by reducing it to mono and dianine, thereby providing a highly efficient catalyst for fixing olefin oxide of carbon dioxide and producing alkylene carbonate. Things.

[0016]

Next, the present invention will be described more specifically with reference to examples. Example 1 Three-electrode electrolytic cell (platinum plate electrode, electrode area 1.85)
cm ² , capacity 7ml, anode and cathode are isolated in each compartment)
2.5 mg (3 × 10 ⁻⁶ mol) of palladium tetra-tert-butylphthalocyanine, CH ₃ CN: CH ₂ C
6 ml of a mixture of l ₂ = 4: 1, 40 mg of Bu ₄ NBF ₄
(0.02 mol / l), argon gas was blown into the solution for 15 minutes, and then electrolysis was performed under a static potential condition of -0.94 V against a saturated silver chloride electrode.

After completion of the electrolysis (after the current value has dropped to 10% of the initial value), the current of the cell was turned off, carbon dioxide was passed through the solution for 30 minutes, and propylene oxide which had previously been blown with argon was used. 2 ml were added. Carbon dioxide was further blown into this mixed solution for 30 minutes, and the mixture was pressure-fed to a Shlenk bottle with argon, and then the degree of progress of the reaction was examined with an infrared spectrometer. As a result, 7.5 × 10 ⁻⁵ mol of propylene carbonate was obtained. That is, catalyst 1
The number of catalyst cycles per mol was 25.

Example 2 Unlike Example 1, a graphite rod for electrolysis (having a diameter of 5 mm and having several small holes for blowing carbon dioxide) was used as an electrode instead of a platinum plate, and a C electrode was used in the electrolysis cell.
H ₃ CN 2 ml, Bu ₄ NBF ₄ 13 mg (0.02 mol
l / l) and 1 ml of epiflorhydrin (1.3 × 10
^-2 mol) was used as an electrolyte. The palladium phthalocyanine previously substituted with tetra-tert-butyl was applied to the graphite electrode in the following manner.

[0019] Pc ^t Pd 0.8 mg of (10 ^-6 mol) C
Dissolve in 0.5 ml H ₂ Cl ₂ (distilled over CaH ₂ before). A graphite electrode is immersed in this solution for 1 minute, pulled up and dried with warm air. This operation is repeated two or three times until the entire amount of the solution has been applied to the electrode end. The electrode rod thus prepared was immersed in the electrolytic solution, and carbon dioxide was constantly blown in while applying a potential of -0.94 V. After 2.5 hours, the mixture was pumped into a Shlenk bottle with argon, and the reaction was performed using an infrared spectrometer. The degree of progress was inspected. 2.25 × 10 ⁻⁴ mol of fluoromethylethylene carbonate were obtained. That is, the number of catalyst cycles per mol of the catalyst was 225.

Example 3 The difference from Example 2 above was that tetra-tert was used as the catalyst.
0.74 mg (10 ^-6 mol) of -butylphthalocyanine was used, and the applied potential and the reaction time were -1.12 V and 1 hour and 15 minutes, respectively. 2.2 × 10 ^-3 mol of fluoromethylethylene carbonate was obtained. That is, the number of catalyst cycles per mole of catalyst is 2 × 1
0 was ^3.

Example 4 The same conditions as in Example 3 except that the reaction time was 2 hours and 30 minutes.
3.5 × 10 ^-3 mol of fluoromethylethylene carbonate, catalyst 1
3.5 × 10 ³ catalyst cycles per mol.

Example 5 Diphthalocyanine of lutetium (Lu) as catalyst
2 mg (10 ^-6 mol), and the applied potential was -0.0.
The same conditions as in Example 4 except that the voltage was set to 10V. 1.1 × 10 ⁻⁴ mol of fluoromethylethylene carbonate, number of catalyst cycles per mol of catalyst 1.1 × 10 ² .

Example 6 1.6 mg (10 ^-6 mol) of diphthalocyanine of praseodymium (Pr) substituted with tetra-tert-butyl as a catalyst
l) and the same conditions as in Example 5 except that the applied potential was -0.10 V. 4. Fluoromethyl ethylene carbonate
3 × 10 ^-4 mol, number of catalyst cycles per mol of catalyst 5.3 × 10 ² .

Example 7 The same conditions as in Example 4 except that the applied potential was -0.74 V. Fluoromethyl ethylene carbonate 4.3 × 10 ^-4 mo
l, number of catalyst cycles per mol of catalyst 4.3 × 1
0 ² .

The reagent used in each of the above examples can be increased up to 10 times. In this case, it is only necessary to simply increase the cell capacity and the electrode area. Since the structure of the catalyst does not change during the reaction, the longer the reaction time, the more easily the number of catalyst cycles can be increased. In addition to the above examples, there are also examples using mono and diphthalocyanine complexes of various metals and other types of epoxides. Based on the data thus obtained, we propose a new and effective method for activating catalysts consisting of mono- and diphthalocyanine complexes of transition and rare earth elements or of metal-free tetra-tert-butylphthalocyanine. be able to. These compounds, which are inactive under normal conditions (20 ° C., atmospheric pressure), can be reduced to the mono- or diamine form to convert them to active catalysts that can be used in carbon dioxide fixation reactions using epoxides. It is possible.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Butane Kim Petrovic, Russian Federation, 113191, Moscow, Futaraya Lasinskaya Street 11 Kubarchira 44 (72) Inventor Corgan Evgeniya Grigorievna Russian Federation, 141008, Shelvakowa, Mytishchi, Moscow 8/40, Kbal Chilla 33 (72) Inventor Tommy Loalisa Lisa Gordvigovna, Russian Federation, 141700, Moscow Dolga Prudny, Pazaev Boulevard 18, Kubarchira 45 (72) Inventor Zephyrov Nikolai Serafimovich Russian Federation, 117421, Moscow Lenin Boulevard 99 Kubarchira 553

Claims (8)

[Claims] 1. A method for fixing by reacting carbon dioxide with oxirane in the presence of a catalyst, comprising using an electrochemically activated phthalocyanine complex as a catalyst. 2. The method according to claim 1, wherein the reaction is carried out at room temperature under atmospheric pressure. 3. A phthalocyanine catalyst comprising tert-
2. A planer or sandwich derivative of a butyl-substituted phthalocyanine complex is used.
Or the method of 2. 4. A catalyst for fixing carbon dioxide to oxirane, comprising a tert-butyl phthalocyanine complex of a metal-free, divalent metal, trivalent metal or tetravalent rare earth element. 5. The metal or rare earth element is palladium,
The catalyst according to claim 4, which is lutetium (Lu) or praseodymium (Pr). 6. The catalyst according to claim 4, which is in a uniform form. 7. The catalyst according to claim 4, which is fixed on a solid support. 8. The catalyst according to claim 7, wherein the solid support is graphite.