New zns photocatalyst, its reception and the method of producing hydrogen with its application

 

(57) Abstract:

Describes the new ZnS photocatalyst for hydrogen production the following formula: Pt(x)/Zn[M(y)]S, where x denotes the Pt content in the photocatalyst in mass percent, in the range of 0.05-2.50, the M denotes a promoter, which is a member selected from the group including V, Cr, Mo, Mn, Re, Ru, Os, Rh, Ir, Cu, Al and Ga, and y denotes M/(M+Zn) in a molar percentage in the range of 0.01-20,00. Describes how to obtain and method of producing hydrogen with its use. The technical result - the creation of a new photocatalyst for hydrogen production, which would show optical activity with emission in the visible region of the spectrum and would also provide the opportunity for effective production of large quantities of hydrogen. 3 S. and 8 C.p. f-crystals, 1 table.

The present invention relates to a new photocatalyst, in particular, to a photochemical reaction, during which the presence of the photocatalyst from the water efficiently and effectively get the hydrogen. The present invention relates also to the preparation method of photocatalyst and method of producing hydrogen.

Background of the invention

Hydrogen is a very important matogo, it is an important material in the hydrogenation process in which the unsaturated compound is transformed into saturated and Hydrotreating processes, including the accession of hydrogen, desulfurization, denitrogenization and demeterova. Another example of using hydrogen is the contact hydrogenation of carbon dioxide, where the carbon dioxide that causes global warming, regenerate, immobilizer and use again. Moreover, hydrogen is considered as a non-polluting clean energy alternatives to fossil fuels.

Modern technology of producing hydrogen include the extraction of fossil fuels such as oil, modification of natural gas, the interaction of steam with iron at high temperatures, the interaction of water with the alkaline metal, electrolysis of water, etc.

However, due to the necessary costs of excessive amounts of heat or electrical energy, these technologies from an economic point of view considered unprofitable. With regard to the modification of fossil fuels, known technologies another inherent disadvantage in the selection of a large number of podima to solve such problems, as the service life of the electrodes and the allocation of by-products. Thus, due to the mentioned problems is the cost of technical means upon receipt of the hydrogen to be economically inefficient.

Due to the low specific weight of hydrogen easily overcomes the force of gravity. The largest part of the hydrogen contained in water or in the form of inorganic materials. For these reasons, in the atmosphere is only a small amount of hydrogen. Obtaining pure hydrogen contained in the form of inorganic materials, also associated with very large technological difficulties and cost-inefficient. Development of technologies for the efficient production of high-purity hydrogen from water is very important and critical to the creation of alternative energy sources.

Recently developed technology for producing hydrogen, in which the decomposition of water into hydrogen and oxygen used photochemical catalyst. To date, however, the technique of photochemical catalysts hydrogen devoted very few publications. Typical examples of publications are published patent applications JP 62-191045 and 63-107815 in the name of Sho.

Wylo the tvii compounds of rare earth element reaction photolysis. The advantage of the compounds of rare earth element is in the optical manifestation of catalytic activity with emission in the visible region of the spectrum.

Published patent application JP 63-107815 on the name Sho refers to the photolysis reaction, during which the photochemical catalyst for producing hydrogen from methanol solution in water use composite oxide of niobium and alkaline-earth metal. Anlogichnym, the advantage of this photochemical catalyst is active radiation in the visible region of the spectrum.

However, both of these previously known methods inherent disadvantages, because the amount received in their implementation of hydrogen is 10 ml/0.5 g/H.

According to the patent in South Korea 95-7721, 95-30416 and 96-44214 the above problems to some extent solved by using the proposed photocatalyst following formula I:

Cs(a)/K4Nb6O17< / BR>
When working on such technology on the environment is low impact and is able to produce hydrogen at room temperature. However, oxygen-containing organic compounds that day the agents.

In the patent application in South Korea 95-30416 offered photocatalyst following formula II:

Cs(a)H(c)/S(b)

When working on such technology on the environment is low impact and is able to produce hydrogen at room temperature without oxygen-containing organic compounds as the promoter of hydrogen, however, there are certain problems associated with the durability and stability of the photocatalyst.

For example, when the carrier of the photocatalyst is impregnated with an alkaline metal such as cesium, significantly increases the amount of hydrogen, but the stability of the catalyst is reduced.

In addition, in the patent application in South Korea 96-44214 offered photocatalyst following formula III:

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

where "a" denotes the Pt content in the photocatalyst wt.%, in the range of 0.1 to 3.5, "M" refers to a promoter selected from the group including Co, Fe, Ni and P, and "b" denotes the content of M in mol.%. When working on such technology on the environment is a weak effect. This connection is characterized not only by a specific optical activity of the photocatalyst, but also consider, that depends on the electron donor and reductants, and the amount of hydrogen greater than the known methods.

When doping by Pt instead of Cs stability of the catalyst is increased, but the choice of promoter is narrowed, and the amount of hydrogen is too low. Furthermore, the preparation of such a photocatalyst due to some problems. This requires double sintering and re-rinse, which combines with the acid pickling after the primary sintering.

Description of the invention

Based on the foregoing, the present invention is to solve the aforementioned problems encountered in the art, and the creation of new photocatalyst for hydrogen production, which would show optical activity at radiation in the visible spectral range (adjustable optical filter), and would also provide the opportunity for effective production of large quantities of hydrogen.

Another objective of the present invention is to provide a photocatalyst, which is characterized by semi-permanent service life.

In addition, the present invention is to develop a UE is of bjectiv the present invention offers a photocatalyst following formula IV:

Pt(x)/Zn[M(y)]S

in which "x" denotes the Pt content in wt.%, in the range of 0.05-2.50, the "M" represents a metal element selected from the group including V, Cr, Mo, Mn, Re, Ru, Os, Rh, Ir, Cu, Al and Ga, and y denotes M/(M+Zn) in mol.% in the range of 0.01-20,00.

Another object of the present invention is a method of producing photocatalyst, including the dissolution of Zn-containing and M-containing compounds in the water so that the molar percentage of M was in the range of 0.01 to 20, adding to the solution with stirring H2S and/or Na2S as a reagent in a quantity sufficient to precipitate Zn[M]S, washing the resulting precipitate with water up until the pH of wash water reaches 7, followed by drying the precipitate, adding to that the resulting draught of liquid Pt-containing compound to obtain a precipitate comprising 0.05 to 2.50 wt.% Pt doping Zn[M]S through Pt, for example by treatment with UV radiation in a nitrogen atmosphere, leaching doped by Pt sediment water up until the pH of wash water reaches 7, and drying, oxidation sintering in air at 280-420oC for 1-3 h and reductive sintering (for example, in an atmosphere of nitrogen/hydrogen ratio 95/5) D. get in the way, in which UV radiation or radiation in the visible spectral range (adjustable optical filter) is treated with a suspension of photochemical catalyst in water, in which pre-enter Na2S (as electron donor) and NaH2PO2(as reducing agent).

The preferred embodiment of the invention

In seeking solutions to the above problems, it was found that as the effective component M as promoter of the photocatalyst according to the present invention can be used V, Cr, Mo, Mn, Re, Ru, Os, Rh, Ir, Cu, Al and Ga, and Fe, Co, Ni and P (patent application in South Korea 95-30416).

It was found that as the electron acceptor Pt effective when the amount of 0.05-2.50 wt.%. When the content is below 0.05 wt.% the amount of hydrogen decreases and decreases the stability of the photocatalyst. On the other hand, the amount of hydrogen decreases, and when the amount is more than 2.50 wt.%, and the cost of hydrogen produced increases.

Acceptable content of M in such a photocatalyst is 0.01-20,00 mol.%. When the content is below 0.01 M mol.%, the efficiency of the photocatalyst is reduced, and when the content is the ratio of Zn/S is from 1:0 to 1:2,8, preferably from 1:0.6 to 1:1,4. In this range of molar ratios of the photocatalyst exhibits increased efficiency.

Sintering in an oxidizing and reducing conditions and drying after reaching pH 7 perform for the reason to keep the elementary state of Pt, which is the electron acceptor, in which the photocatalyst. According to reports, under the influence of UV radiation during the reaction of Pt in H2PtCl6associated with S compounds ZnS, forming PtS, and at temperatures above 300oC for several hours in an oxidizing and reducing conditions is transformed into the structure of wurtzite and at the same time in the sintering process at temperatures above 300oC for 1-2 h Pt, which is the acceptor of the electrons is transformed into Pt(0).

Examples of Zn-containing compounds are ZnSO47H2O and Zn(NO3)26H2O. Other examples of M-containing compounds are VCl3, VOSO4, VOCl3, K2Cr2O7, Cr(NO3)3, MFN3, ReCl3, MoCl5, FeCl3, Fe(NO3)3, RuCl3, Co(NO3)2, CoCl2, Co(CH3COO)2, RhCl3Rh(NO3)3, IrCl3, Ni(NO3)2, NiCl2UB> and H3PO2.

In the patent application in South Korea 96-44214 proposed method comprising leaching from acid after acid etching followed by the primary sintering, and the present invention is only required vacuum drying in a nitrogen atmosphere and without primary sintering, acid etching and leaching of acid.

In the preferred embodiment, are impregnated Zn[M]S platinum, including the dissolution of hexachloroplatinic acid (H2PtCl6in the water, add the prepared solution to Zn[M]S, and then processing the resulting product is UV-irradiation, washing Zn[M]S, impregnated Pt, up until the pH of wash water reaches 7, and vacuum drying the impregnated Pt precipitate in a nitrogen atmosphere and at 100-120oC for 1.5-2.5 h with subsequent oxidative sintering at a temperature of 280-420oC for 1-3 h and reductive sintering at a temperature of 280-420oC for 1-3 h

In fact, according to a preferred variant, the sintering is carried out at a temperature of 320-400oC, because outside of this temperature range service life and activity of the prepared photocatalyst decreases.

In accordance with the present SUB>2PO2(as reducing agent) in primary and/or secondary distilled water or pre-treated water and added to a solution of the photocatalyst according to the present invention. Then cooked in this way, the suspension is treated with UV irradiation or irradiation in the visible spectral range (adjustable optical filter) with stirring at a temperature of 5-85oC and a pressure of 0.1 to 5 atmospheres with high hydrogen yield.

When the concentration of electron donor and reductant below the specified lower limit, the amount of hydrogen decreases. On the other hand, when the concentration of electron donor and a reducing agent exceeds the upper limit, the amount of hydrogen does not increase. Acceptable reaction conditions include a temperature of 10-60oC and pressures from vacuum to less than 2 ATM.

THE EXAMPLE I GET

In 250 ml of water with stirring enter 1 molar proportion of ZnSO47H2O, of 0.005 molar fraction of Al(NO3)39H2O and H2S in a quantity sufficient to precipitate Zn[Al]S. Precipitate washed with water up until the pH of the resulting wash water reaches 7. Next washed thus precipitate dried under ablaut hexachloroplatinic acid (H2PtCl6in number, in which the Pt content in the sediment reaches 0.8 wt. %. Alloyed platinum precipitate is treated with UV irradiation (mercury lamp high pressure power 450 W at a distance from the light source to the sample 4 cm) for 0.5 h to obtain Pt/Zn[Al]S. Washed with Pt/Zn[Al] S water up until the pH of the resulting wash water reaches 7. Then the washed precipitate Pt/Zn[Al]S dried in a nitrogen atmosphere at 110oC for 2 hours Washed and thus dried precipitate is subjected to oxidative sintering in air at 370oC for 1.5 h with getting as photocatalyst Pt (0.8 wt.%)/Zn[Al]s

AN EXAMPLE OF RETRIEVING II

Working analogously to example I get using a 0.01 molar fraction (instead of 0.005 molar fraction) Al(NO3)39H2O, and receiving as a photocatalyst Pt(0.8 wt.%)/Zn[Al]s

AN EXAMPLE OF RETRIEVING III

Working analogously to example I get using a 0.05 molar fraction (instead of 0.005 molar fraction) Al(NO3)39H2O, and receiving as a photocatalyst Pt(0.8 wt.%)/Zn[Al]s

AN EXAMPLE OF OBTAINING IV

Working analogously to example I get using a 0.05 molar fraction of H3PO2[instead of Al(NO3)39H2O] and will receive a receipt I, using a 0.005 molar fraction of H3PO2[instead of Al(NO3)39H2O], and receiving as a photocatalyst Pt(0.8 wt.%)/Zn[P]s

AN EXAMPLE OF RETRIEVING VI

Working analogously to example receiving IV using hexachloroplatinic acid in a quantity sufficient for the introduction of sediment to 0.4 wt.% (instead of 0.8 wt.%) Pt, obtaining as a photocatalyst Pt(0.4 wt. %)/Zn[P]s

AN EXAMPLE OF RETRIEVING VII

Working analogously to example receiving IV using hexachloroplatinic acid in a quantity sufficient for the introduction of sediment to 2.5 wt.% (instead of 0.8 wt.%) Pt, obtaining as a photocatalyst Pt(2.5 wt. %)/Zn[P]s

EXAMPLES OF RECEIVING VIII-XXIV

Working analogously to example I get varying M-containing compound, with the receipt of each of the photocatalytic compositions of Pt(0,8 wt. %)/Zn[M]S, are presented in table I.

EXAMPLES I-XXIV

0.5 g of each of the photocatalysts prepared in examples obtain I-XXIV, suspended with stirring with the mixer rotation speed of 400 rpm) in 500 ml of water which contains 0,24 molar fraction of Na2S and 0.35 molar fraction NaH2PO2in a photochemical reactor closed gascirculation system. Ready the practical filter (which passes light with a wavelength of more than 400 nm) at a distance from the sample to the light source 4 cm] at room temperature under a pressure of one atmosphere. The amount of hydrogen, which thus receive (according to gas chromatographic analysis) are listed in table I.

EXAMPLE XXV

Working analogously to example I, using the photocatalyst prepared in example receiving IV, except that instead of radiation in the visible region of the spectrum used UV-irradiation (mercury lamp high pressure power 450 W at a distance from the light source to the sample 4 cm) and receive the results presented in table I.

COMPARATIVE EXAMPLE I

Working analogously to example XIX, but without the stages of the oxidative/reductive sintering in the preparation of the photocatalyst. In accordance with the method described in examples I-XXIV using the photocatalyst, the hydrogen is produced in the amount indicated in table I.

COMPARATIVE EXAMPLE II

In accordance with a method described in the patent application in South Korea 96-44214 using the same composition as shown in the example of obtaining X, get dried precipitate and then the residue is treated in the following way: the primary sintering, etching with nitric acid and a secondary sintering to obtain a photocatalyst. If you use this photo

Industrial applicability

From the data of table I it is evident that the photocatalyst producing hydrogen in accordance with the present invention can be used in conjunction with the promoters of various types, and the quantity of hydrogen produced using this new catalyst exceeds the number who receive by known methods. Moreover, this photochemical catalyst characterized by a longer service life, and the preparation method of photocatalyst much easier known methods.

The present invention, which offers a new photocatalysts obtained by introducing alloying metal elements of different types, ways of their introduction and use of the catalyst, allows not only to eliminate the above-mentioned limitation of the activity of photocatalysts in terms of sources of radiation, but also to facilitate the obtaining of photocatalysts, which are characterized by increased expected service life and performance of hydrogen.

The invention and its advantages are apparent from the above description. It is obvious that the proposed methods and compositions can be made variety is like to illustrate preferred embodiments of the invention.

1. ZnS photocatalyst for hydrogen production the following formula:

Pt(x)/Zn[M(y)]S,

in which x denotes the Pt content in the photocatalyst in mass percent, in the range of 0.05-2,50;

M denotes a promoter, which is a member selected from the group including V, Cr, Mo, Mn, Re, Ru, Os, Rh, Ir, Cu, Al, and Ga;

y denotes M/(M+Zn) in a molar percentage in the range of 0.01-20,00.

2. ZnS photocatalyst under item 1, characterized in that M is selected from the group including V, Cr, Mo, Mn, Re, Ru, Os, Rh, Ir, Cu, Al and Ga.

3. The method of preparation of ZnS photocatalyst for hydrogen production under item 1, including the dissolution of Zn-containing compound and M-containing compounds in the water so that the value of M/(M+Zn), expressed in molar percent, was in the range of 0.01 to 20, adding to the solution with stirring N2S or Na2S as a reagent in a quantity sufficient to precipitate Zn[M] S, washing the resulting precipitate with water up until the pH of wash water reaches 7, the vacuum drying the washed precipitate in the atmosphere (current) nitrogen addition to Zn[M]S liquid Pt-containing compound in a quantity sufficient for impregnation Zn[M]S amount constituting from about 0.05 to 2.50 wt. % Pt, in combination with abrabae will reach 7, processing the washed and soaked Zn[M]S vacuum drying and subsequent oxidative sintering at 280-420oC for 1-3 h and reductive sintering sintered thus product when 280-420oC for 1-3 h

4. The method according to p. 3, wherein M is selected from the group including V, Cr, Mo, Mn, Re, Ru, Os, Rh, Ir, Cu, Al and Ga.

5. The method according to p. 3, characterized in that the M-containing compound selected from the group comprising VCl3, VOSO4, VOCl3, K2Cr2O7, Cr(NO3)3, MFN3, ReCl3, MoCl5, FeCl3, Fe(NO3)3, RuCl3, Co(NO3)2, CoCl2, Co(CH3COO)2, RhCl3Rh(NO3)3, IrCl3, Ni(NO3)2, NiCl2Pd(NO3)2, CuCl2, Cu(NO3)2, CuSO4, Al(NO3)3, AlCl3, Ga(NO3)2and H3PO2.

6. The method according to p. 3, characterized in that the vacuum drying is carried out at a temperature of 100-120oC for 1-3 h

7. The method of producing hydrogen, which comprises processing with stirring aqueous suspension of photocatalyst under UV light or radiation in the visible spectrum and in which the aqueous suspension includes 0,15-0,40 mol.% Na2S kachestve photocatalyst under item 1.

8. The method according to p. 7, characterized in that it is carried out at a temperature of 10-60oWith under vacuum or pressure up to 2 ATM.

9. The method according to p. 7, characterized in that the irradiation is carried out using UV radiation.

10. The method according to p. 9, characterized in that the UV-radiation using radiation of a mercury lamp high pressure output of 450 watts, as the radiation source, which is placed at a distance of 4 cm from the irradiated suspension of the photocatalyst.

11. The method according to p. 9, characterized in that the radiation in the visible region of the spectrum using the radiation of a xenon lamp with an output of 500 W with an optical filter that passes light with a wavelength of more than 400 nm as a radiation source, which is placed at a distance of 4 cm from the irradiated suspension of the photocatalyst.

 

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