New photochemical zns-catalyst, receive and methods for producing hydrogen with its application

 

(57) Abstract:

The invention relates to chemistry, in particular to a method for photochemical catalyst and its use for hydrogen production in photochemical reactions. Dissolve in water Zn-containing and M-containing compounds. Precipitated Zn[M] S using H2S or Na2S. Washed, dried, is sintered. Poison acid, washed and dried. Impregnate Zn[M]S platinum by treatment with UV radiation. Washed, dried, and is sintered. The result of photochemical catalyst of the formula: Pt(a)/Zn[M(b)]S, where a = 0.1 to 3.5 wt.%; M - Co, Fe, Ni, R; b = 0.05 to 30 mol.%. The hydrogen is produced, the processing of UV-radiation or radiation of the visible spectrum, the suspension of photochemical catalyst in water in the presence of Na2S and NaH2PO2. Such a catalyst may be active in the visible region of the spectrum, working in quasi-stationary mode and provides hydrogen production with high yield without using any oxygen-containing organic compounds as the promoter of the formation of hydrogen at a low temperature, for example at room temperature. 3 s and 5 C.p. f-crystals, 1 table.

The present invention relates to navamsa effective and economical production of hydrogen from water in the presence of photochemical catalyst. In addition, the present invention relates to a method for photochemical catalyst and method of producing hydrogen.

Background of the invention

Hydrogen is a very important substance for the chemical industry. For example, it is used for obtaining ammonia and in the synthesis of hydrogen chloride. Moreover, it is an important reagent in the process of hydrogenation, in which the unsaturated compound is transformed into saturated. In addition, hydrogen plays a major role in improving the quality of petroleum products, i.e., Hydrotreating processes, including the accession of hydrogen, flue, diazotoluene and demetilirovania. Another example of using hydrogen is the process of contact hydrogenation of carbon dioxide, where the carbon dioxide that causes global warming, clean, immobilizer and use repeatedly. In addition, hydrogen is considered as a non-polluting, clean source of energy, replacing existing fossil fuel.

Conventional technology for producing hydrogen is extracted from fossil fuels, such as oil, modified natural gas, the interaction of steam with iron, vzaimode the implementation requires a huge amount of heat or electrical energy. Conventional technology characteristic and another drawback consisting in the formation of large amounts of by-products, carbon dioxide or oxygen (electrolysis). As noted above, carbon dioxide is a major source of environmental pollution on a global scale causing the greenhouse effect. When oxygen is formed, separating hydrogen from oxygen associated with technological difficulties, because of which the process becomes more complicated. In any case, these by-products could create difficulties in obtaining high-purity hydrogen with high yield. Since the process of producing hydrogen using such conventional methods, as a rule, carried out at relatively high temperatures, most of the used for this equipment, such as reactors and cleaning devices, design so that it had the necessary heat resistance because of what it turns out to be very expensive, which is economically unfavorable factor.

Due to its low specific weight, the hydrogen gas is able to easily overcome the force of attraction of the earth; a large part of the hydrogen is in the form of water or on the Kim way the development of technology that would effectively get out of the water high-purity hydrogen is very important because it allows us to solve the problem of creating a replacement energy sources and to provide the chemical industry with raw materials.

Recently developed technology for producing hydrogen, in which the decomposition of water into hydrogen and oxygen using a photochemical catalyst. However, there are currently only a small number of publications that describe the photochemical catalyst used to produce hydrogen, and which include, for example, published patent applications Japan Sho. 62-191045 and Sho. 63-107815.

In lined with the patent application of Japan's Sho. 62-191045 says that by conducting the reaction photolysis of aqueous solution of Na2S in the presence of compounds of rare earth element emit hydrogen. The advantage of the compounds of rare earth element is that when radiation in the visible spectrum it manifests optical catalytic action.

In lined with the patent application of Japan's Sho. 63-107815 described the photolysis reaction, during which the evolution of hydrogen from the methanol solution in water as Fatah is at once the advantage of this photochemical catalyst is to show them the activity in the radiation in the visible region of the spectrum.

However, such previously known technical solutions inherent disadvantages, namely that the amount of hydrogen is very small.

In accordance with the patent application in South Korea 957721, filed by one of the authors of the present invention, it is proposed photochemical catalyst, with which, as I think, can to a certain extent to solve the above problems and which corresponds to the General formula I:

Cs(a)/K4Nb6O17< / BR>
In the presence of this photochemical catalyst ultraviolet rays treated with an aqueous solution mixed with oxygen-containing organic compounds such as formaldehyde and the alcohol acting as accelerators of hydrogen, with hydrogen production.

In the practical implementation of this method on the environment is only a small effect, and this method allows you to produce hydrogen at a low temperature, e.g. at room temperature. However, the application of oxygen-containing organic compound as an accelerator of hydrogen leads to the impossibility of re-use reagents.

Description of the invention

Based on beseitigen the camping experience when they work by known techniques, and create a new one photochemical catalyst for production of hydrogen, which showed least activity at radiation in the visible spectrum and which could efficiently to get large amounts of hydrogen at low temperature, for example at room temperature, without the use of oxygen-containing organic compounds.

Another objective of the present invention is to develop a method of preparation of photochemical catalyst.

Further, another object of the present invention to provide an economical method of producing hydrogen using a photochemical catalyst.

Thus, the invention offers a photochemical catalyst of the General formula II:

Pt(a)/Zn[M(b)]S

in which the symbol "a" denotes the mass percentage of Pt in the photochemical catalyst comprising from 0.1 to 3.5, the symbol "M" denotes the element selected from the group including Co, Fe, Ni and P, and the symbol "b" represents the value of the molar percentage of M/Zn, comprising from 0.05 to 30.

In the invention it is further proposed a method of preparation of photochemical catalyst, in which the Zn-containing what about the ratio M/Zn is 0.05-30, in this solution with stirring enter H2S or Na2S as a reagent deposition of Zn[M]S, the residue is washed with water until such time as the value of its pH reaches 7, and dried, and then the precipitate is sintered at 250-350oC for 1-3 h, etched with acid, again washed with water up until the pH reaches 7, dried, and bake.

In the invention it is also proposed a method of producing hydrogen in which ultraviolet radiation or radiation in the visible region of the spectrum affect the suspension of photochemical catalyst in water, which is injected Na2S as an electron donor and NaH2PO2as the reductant.

The preferred embodiment of the invention

Performing the function of the promoter, the component M in the photochemical catalyst of the present invention is an element selected from the group including Co, Fe, Ni and P, and is preferably used in such quantities, at which the value of the molar percentage of M/Zn is about 0.05-30. For example, when using a too small number of component M, ion Zn2+in this photochemical catalyst is restored to dark gray Zn, the ability of hydrogen is significantly reduced.

In photochemical catalyst of the present invention Pt serves as the electron acceptor, which in the preferred embodiment is used in an amount of 0.1 to 3.5 wt. %. However, when the amount of Pt is less than the lower limit, the rate of formation of hydrogen using a photochemical catalyst becomes too low, as well as decreasing its life. On the other hand, when the Pt content exceeds the upper limit, further increase in the number of generated hydrogen impossible, and it is not economically feasible due to the increasing cost of preparation of the catalyst.

Regarding the content of zinc and sulfur should be noted that the preferred molar ratio between zinc and sulfur is from 1:0.1 to 1:2,8, more preferably from 1:0.6 to 1:1,4. If, for example, this molar ratio is outside these limits, the photochemical efficiency of the catalyst is much lower.

Examples of Zn-containing compounds include ZnSO47H2O and Zn(NO3)26H2O, while M-containing compound can be obtained, for example, of Co(NO3)26H2O, NiCl26H2O, Fe(NO3)29H2O, H3PO2and Hthe pH up to 7 stages of drying and sintering carried out in order to remove the aforementioned acidic salt solution, remaining in the sediment, or other residual acidic solutions.

Etching acid after the primary sintering is conducted with the aim to remove oxides that may be formed on the surface of Zn[M]s Examples of acceptable acids include nitric acid, hydrochloric acid and sulfuric acid, and if you take into account the convenience of processing, the most preferred nitric acid.

In a preferred embodiment, Zn[M]S is impregnated with Pt dissolution of hydrogencarbonate (H2PtCl6) in water, adding the water Zn[M]S and the water treatment ultraviolet radiation. Thus obtained Zn[M]S, impregnated Pt, washed with water to achieve its pH 7, dried at 100-120oC and bake, getting photochemical catalyst according to the invention. While the preferred sintering temperature is 250-350oC. for example, if stage sintering is carried out at a temperature that is below this range, the resulting photochemical catalyst has a short service life. On the other hand, when excessive temperature, the resulting photochemical catalyst characterized by low productivity hydrogen.

To obtain vodo
PO2and add a photochemical catalyst according to the present invention. Then this suspension with stirring, treated with radiation of the visible spectrum or UV radiation. When Na2S and NaH2PO2use the number that is less than, respectively 0.15 and 0.40 moles of moles, the performance of hydrogen decreases. On the other hand, when the amount of Na2S and NaH2PO2exceed their individual upper limits, to achieve further productivity gains hydrogen impossible.

In a preferred embodiment, the process of producing hydrogen using a photochemical catalyst according to the present invention is carried out at a temperature of 10-60oC in vacuum or under pressure up to 2 ATM.

Below the invention is explained in more detail by examples, which are presented only for the purpose of illustration and therefore should not be considered as limiting the scope of invention.

The example I get

In 500 ml of water was injected 143,77 g ZnSO47H2O and 0.29 grams of Co(NO3)6H2O, obtaining a suspension of 0.2 moles Co/Zn. In this suspension as a reagent was added H2S and mixed with obtaining a precipitate, which is then washed odcienie 2 h and was protravlivanie nitric acid for 1 h End potraviny and sintered mass was again washed with water until until its pH value reached 7, followed by drying in vacuum at 60oC, receiving the powder ZnCoS.

To this powder was added hydrogenchloride (H2PtCl6and within 30 minutes was treated with UV radiation with the purpose of impregnation of the carrier 2 wt.% Pt. Thus obtained powder Pt/ZnCoS again washed with water until such time as the value of its pH reached 7, dried at 110oC for 12 h, were subjected to oxidative sintering at 300oC for 2 h and then subjected to reductive sintering at 300oC for 2 h, the receiving end Pt/ZnCoS photochemical catalyst.

Examples of receipt II and III

Worked as in example I get from the use of such controlled amounts of Co(NO3)26H2O, in which the values of the molar percentage ratio of Co/Zn was 0.6 and 1.0.

Examples of receiving IV-VI

Worked as in example I get, except that instead of Co(NO3)26H2O used Fe(NO3)29H2O, NiCl26H2O and H3PO2in such quantities, at which the value of the molar procent is alization, prepared in the examples obtain I-VI, suspended in 500 ml of water which contained 0.24 M Na2S and 0.35 M NaH2PO2and mixed with the mixer rotation speed of 400 rpm in a photochemical reactor with a closed air circulation system. Using a mercury high-pressure lamps for irradiation of suspensions radiation in the visible spectral region at room temperature and under the pressure of the atmosphere was obtained hydrogen. Determined quantity of the hydrogen produced, which was analyzed using a gas chromatograph. The results obtained are summarized in table 1.

Comparative example I

Hydrogen was obtained analogously to example I, except that the photochemical catalyst was prepared in such a way that the value of the molar percentage ratio of Co/Zn was 0.04. The results obtained are presented in table 1.

Comparative examples II-V

Hydrogen was obtained analogously to example I, except that the photochemical catalyst was prepared in such a way that the value of the molar percentages of each Co/Zn, Fe/Zn, Ni/Zn and P/Zn was 40. The results obtained are presented in table 1.

Example VII

Works

Example VIII

Worked with the aforementioned method using Na2S at a concentration of 0.15 M. the Obtained results are presented in table 1.

Comparative example VI

Worked with the aforementioned method using Na2S in a concentration of 0.1 M. the Obtained results are presented in table 1.

Example IX

Worked with the aforementioned method using Na2S at a concentration of 0.4 M. the Obtained results are presented in table 1.

Comparative example VII

Worked with the aforementioned method using Na2S in a concentration of 0.5 M. the Obtained results are presented in table 1.

Example X

Worked with the aforementioned method using NaH2PO2at a concentration of 0.2 M. the Obtained results are presented in table 1.

Comparative example VIII

Worked with the aforementioned method using NaH2PO2at a concentration of 0.15 M. the Obtained results are presented in table 1.

Example XI

Worked with the aforementioned method using NaH2PO2at a concentration of 0.15 M. the Obtained results are presented in table 1.

Comparative primay the results are presented in table 1.

Industrial applicability

As can be seen from the above data, provided in accordance with the present invention photochemical catalysts for performance and durability, as well as activity at radiation in the visible spectrum surpass known.

It should be noted that the invention described above in the illustrative example variant of its execution, not its bounding volume. In addition, in the invention it is possible to make various changes and modifications. Thus, the scope of the invention is limited only by the claims.

1. Photochemical ZnS-catalyst for hydrogen in the General formula II

Pt(a)/Zn[M(b)]S,

in which the symbol "a" denotes the mass percentage of Pt in the photochemical catalyst comprising from 0.1 to 3.5, the symbol "M" denotes the element selected from the group including Co, Fe, Ni and P, and the symbol "b" represents the molar percentage ratio M/Zn, the value of which ranges from 0.05 to 30.

2. The catalyst p. 1, in which the value of b is from 0.1 to 2.8.

3. The method of preparation of photochemical catalyst, in which the Zn-containing and M-containing compound (where the value M is chosen from Co, Ni, Fe and P) races is 30, to the resulting solution under stirring enter H2S or Na2S as a reagent deposition of Zn[M]S, the residue is washed with water until such time as the value of its pH reaches 7, dried, bake at 250 - 350oC for 1 to 3 h, etched with acid, again washed with water up until the pH reaches 7, then dried, to the obtained Zn[M]S add liquid Pt-containing compound for impregnation of Pt in an amount of about 0.1 to 3.5 wt.% by treatment with UV radiation, Zn[M] S, impregnated Pt, washed up until the pH value reaches 7, dried, and bake.

4. The method according to p. 3, in which the M-containing compound is a Co(NO3)26H2O, NiCl26H2O, Fe(NO3)29H2O, H3PO2or H3PO4. 5. The method according to p. 3, in which stage of sintering includes sequentially carried out by oxidative sintering and reductive sintering.

6. The method according to p. 3, in which the Zn-containing compound is a ZnSO47H2O or Zn(NO3)26H2O.

7. The method of producing hydrogen in which ultraviolet radiation or visible radiation region of the spectrum is treated with a suspension of photochemical Katav> as the reductant.

8. The method according to p. 7, in which the hydrogen is produced at a temperature of 10 - 60oWith vacuum or under pressure up to 2 ATM.

 

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