SU1030007A1 - Catalyst for extracting oxygen from water - Google Patents

Description

The invention relates to heterogeneous catalysts for the separation of oxygen from water, namely, compounds of the type of spinel, catalyzing the oxidation of water by chemical oxidants formed in photocatalytic systems. . A catalyst for the release of oxygen from water is known, which is colloidal platinum or palladium or ruthenium Cl. The disadvantage of this catalyst is: low activity. A known catalyst is platinum dioxide or: iridium 2J. The disadvantage of this catalyst is its low activity in the reaction of water oxidation, and also the use of noble metals. A homogeneous catalyst is known, which is a compound of metals of iron, cobalt or copper, for example, iron chloride or cobalt, or a complex compound of cobalt of composition Co (bp) c J (C104) sSZ The disadvantage of this catalyst. its low stability in aqueous solutions due to hydrolysis, as well as insufficiently high oxygen paths in alkaline and especially acidic solutions (70 and 50% of theory at pH 9 and b, respectively. h. The selectivity of catalysts in acid solutions is low. There is a particularly significant drawback for photocatalytic systems, since it is acidic solutions that cause photocatalytic hydrogen evolution. The aim of the invention is to increase the stability and selectivity of water oxidation catalysts to oxygen in a wide range of pH by using heterogeneous catalysts that do not contain platinum group metals. The goal is achieved by using compounds of the spinel type of the general formula M., where M is silver selected from the group containing iron, cobalt, zinc and nickel; metal selected from the group containing chromium, iron and cobalt, or nitrous oxide cobalt as a catalyst for the separation of oxygen from water. These compounds are described as catalysts for the deep oxidation of organic substances, however, oxygen from the water, these catalysts have not been used. When oxygen is released from water, catalysts are required that would transport 4 electrons. The compounds proposed as catalysts allow this process to be carried out with high efficiency in the presence of oxidizing agents. EXAMPLE 1 20 mg of Ru / I lie / g () 3 is dissolved in 20 ml of 5-UZ HgSO and 10 mg of iron FeCrgO pounded into Chromite powder is added as a catalyst. Then, 3.3 ml of 0.2 N NaOH is poured in, while the pH of the solution is changed to ZD. The amount of oxygen liberated in this way is measured by chromatography. Reaction time 5 min at room temperature, eurature. Oxygen yield 3, Ali 60% of stoichiometry. Example 2. The amounts of the complex, catalyst, and acids are the same as in Example 1. 3.9 ml of 0.2N NaOH was added to the resulting solution, with siTOM the pH of the solution increased to 9.6. Oxygen yield 5.7- U mol or 100%. Example 3. 20 mg of Ru (Bpy), j CC204) are dissolved in 20 ml of i 5-1p 3H 3 (HjSO). and, as a catalyst, 10 mg of coba ferrite crushed into powder, LITE CoE / O. is added as a catalyst. The solution is made alkaline with 0.2 N NaOH to pH 3.1, 3.1 to 10 mol O2 or 55% is released. Example 4: The reagents are the same as in Example 1, but 10 mg of cobalt chromite CoCr204 are used as a catalyst. 2.8ID mole 02 or 55% is isolated. Example 5. The reagents are the same as in example 1, but using 10 mg of zinc ferrite ZnFegO as a catalyst. The output of Qj 1,410 mol or 25%. Example b. The reagents are the same as in Example 1, 10 mg of catalyst is added, which is a solid solution of NiCo204 + CoAl204. Yield 0 3.1-10 mol or 55%. Example 7. The reagents are the same as in example 1. 10 mg is used as a catalyst. 5.7 -10 mol of oxygen or 100% is liberated. PR, and measure 8. 20 mg. Pe (plep) CZS204) 3 is dissolved in 20 ml of n and 10 mG of PeCr204 is added as a catalyst. and 3.9 ml of 0.2 N NaOH. With this, the pH of the solution increases to 9.6. Output 02, mol, or 55%. A comparative characteristic of the known and proposed catalysts is presented in the table (known catalysts are marked with an asterisk). The proposed catalysts do not contain noble metals in their composition and are distinguished by high stability in aqueous solutions of pH from 1 to 14 K, which allows us to achieve a high level of activity, a significant increase in eoJiiee than in the known technical solutions, and oxygen

from water under the action of various oxidizing agents, in particular, trisbipi-ridyl and trisphenanthroline complexes of ruthenium (w / osmi Emissions of catalysts, for example, in example 2, corresponds to a release of 0., 7 ml, 02 per hour per mg of catalyst. The catalysts retain their activity when operating in aqueous solutions with a temperature of 0-100 ° C, including 5 irradiation. are specific and allow the use of various oxidizing agents for the release of oxygen.

: RU (2,2 - bipyridil Z

P /

. ".

. ".

- -

P

AND

AND

P

Fe (phenanthroline

-

Cocbj

49 60 48 68 34

Soep2S

Fecig

ReСг20. (Example 1) 100

:

SoSO (G1 Example 2) 100

CoFe 0 {example 3) 55

CoCTgO (example 4) 50

ZnFegOj, C example 5) 25 NiCo, Al.do (example 6) 55

J. about

ReSg-O. (Example 7) 55

Claims (1)

(5 * 7) Use of spinel compounds of the general formula Μ ¹ Μ ^ 0 ^, where M * is a metal selected from the group consisting of iron, cobalt, zinc and nickel "M ² is a metal selected from the group consisting of chromium, iron and cobalt, or nitrous oxide - cobalt oxide as a catalyst for the liberation of oxygen from water.