Cds photocatalyst for hydrogen, its preparation and a method of producing hydrogen with its application

 

(57) Abstract:

Describes CdS photocatalyst for hydrogen production the following formula: m(A)/Cd[M(B)]S, where m denotes the alloying metal element as an electron acceptor selected from the group including Pt, Ru, Ir, Co, Rh, Cu, Pd, Ni, and oxides of these metals; And denotes the mass percentage of m in the range of 0.10-2,50; M denotes a catalytic element selected from the group including V, Cr, Al and P; denotes M/(M+Cd) in a molar percentage in the range of 0.05-20,00. The technical result is to obtain a high yield of hydrogen with unlimited service life of the catalyst. Also describes the preparation of a photocatalyst, method of producing hydrogen using. 3 S. and 9 C.p. f-crystals, 1 table.

The present invention relates to a photocatalyst for hydrogen production, in particular to a photochemical reaction, during which in the presence of CdS 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 with its use.

Background of the invention

Hydrogen is normally used for obtaining ammonia ome, he plays a major role in Hydrotreating processes, including the accession of hydrogen, desulfurization, denitrogenization, demeterova and especially the hydrogenation of carbon dioxide that causes global warming. Moreover, hydrogen is considered as a non-polluting source of energy and as an alternative to fossil fuels.

There are many different types of known methods of producing hydrogen, which include its extraction from 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, since in particular the modification of fossil fuels as a by-product produce large quantities of carbon dioxide. In the case of electrolysis it is necessary to solve problems such as short service life of the electrodes and the selection as a by-product of oxygen. Thus, the solution mentioned problems economically inefficient.

Due to the low specific weight of hydrogen easily overcomes the force of gravity, and 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. Purification of hydrogen contained in the form of inorganic materials are also associated with very large technological difficulties. If it is possible, it is also economically inefficient. Thus, the development of technology for efficient and cost-effective production of high-purity hydrogen from water is very important for solving urgent problems of 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.

According lined the patent application JP 62-191045 on the name Sho hydrogen is produced from an aqueous solution of Na2's reaction photolysis in the presence of compounds of rare earth is that it exhibits optical activity with emission in the visible region of the spectrum.

In lined with the patent application JP 63-107815 on behalf Sho described reaction photolysis, during which as photochemical catalyst for producing hydrogen from methanol solution in water use composite oxide of niobium and alkaline-earth metal. Similarly, the advantage of this photochemical catalyst is optical activity with emission in the visible region of the spectrum.

However, the aforementioned known techniques inherent disadvantages, namely that the amount of hydrogen generated is small, and the performance is 10 ml/0.5 g/H.

In applications for patents in South Korea 95-7721, 95-30416 and 96-44214 suggests that the resolution of the above problems.

In the patent application in South Korea 95-7721 offered photocatalyst following formula I:

Cs(a)/K4Nb6O17(I)

In the presence of photocatalyst of formula I, hydrogen is produced by the processing of UV-radiation of an aqueous solution of mixed oxygen-containing organic compounds such as formaldehyde and alcohol, which act as promoters of hydrogen. When working on such technology on the environment is low impact and provide the organisations, which act as promoters of hydrogen, determine the impossibility of re-use of these reagents.

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

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

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 of formula II.

For example, when the carrier of the photocatalyst is impregnated with an alkaline metal, such as cesium (Cs), 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 described photocatalyst following formula III:

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

When working on such technology on the environment is also a weak impact. Despite the dependence of electron donors and reducing agents, the photocatalyst of formula III is superior to the above-mentioned known technical resending region of the spectrum. However, the amount of hydrogen is economically inefficient.

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 hydrogen with optical activity at radiation in the visible spectrum, an adjustable optical filter, and that the photocatalyst must achieve a high yield of hydrogen with unlimited service life.

One of the objects of the present invention is a photocatalyst following General formula V:

m(A)/Cd[M(B)]S (V)

in which m denotes the alloying metal element as an electron acceptor selected from the group of Pt, Ru, Ir, Co, Rh, Cu, Pd, Ni, or oxidized connection of any of these metals; And denotes the mass percentage of m in the range of 0.10-2,50; M denotes a promoter selected from the group including V, Cr, Al and P; B is M/(M+Cd) in a molar percentage in the range of 0.05-20,00.

The preparation method of photocatalyst according to the invention is notable for the alloying process, which consists in osushestvlyae percentage of M were in the range of 0.05-20,00, adding to the solution with stirring H2S or Na2S as a reagent to precipitate Cd[M] S, washing the precipitate with water up until the pH of wash water reaches 7, the vacuum drying the precipitate in a nitrogen atmosphere and add to that the draught of liquid m-containing compound in such amount, in which the content of m in mass percent is in the range of 0.10-2.50 each.

In accordance with another object of the present invention proposes a method of producing hydrogen, in which the radiation in the visible spectrum, an adjustable optical filter, or sunlight affect the suspension of photochemical catalyst in water, which is injected Na2S (as electron donor) and NaH2PO2(as reducing agent).

The preferred embodiment of the invention

Acting as electron acceptor alloy metal m in the photocatalyst according to the invention is an element selected from the group including Pt, Ru, Ir, Co, Rh, Cu, Pd, Ni, or an oxide, which in the preferred embodiment is used in such amount, in which the content in mass% is 0.10-2.50 each. For example, when the number of component m is Mora. On the other hand, when the number of component m more than 2.50 wt.%, the amount of hydrogen is reduced, and the cost of the resulting product is economically inefficient.

In the photocatalyst according to the invention the value of M is chosen from the group including V, Cr, Al and P, and B denotes M/(M+Cd) in a molar percentage in the range of 0.05-20,00. If the value is less than the lower limit, the activity of the photocatalyst is usually reduced. On the other hand, if the value exceeds the upper limit, the amount of hydrogen decreases. With regard to the amount of cadmium and sulfur, in the preferred embodiment, Malmoe the relationship between cadmium and sulfur are in the range from 1:0.1 to 1:2,8, more preferably from 1:0.6 to 1:1,4. In this interval morrnah ratios photocatalyst exhibits increased efficiency.

If in the preparation of the photocatalyst as the alloying element m using platinum (Pt), in the preferred embodiment, with Pt the processing of UV-radiation should be carried out in a nitrogen atmosphere and legitamate Cd[M]S sintering. In a more preferred embodiment, to draft Cd[M]S add hexachloroplatinic acid (H2PtCl6) and treated with UV irradiation in the atmosphere is about 2,50. Thus obtained precipitate was washed with water up until the pH of wash water reaches 7, then dried under vacuum at 105-120oC for 1.5-2.5 hours, subjected to oxidative sintering at 300-400oC for 1.0 to 2.0 h and then reductive sintering at 300-400oC for 1.0 to 2.0 hours

In the case of other alloying elements in the preferred embodiment, the preparation method of photocatalyst includes adding to the resulting draught Cd[M] S m-containing compounds other than platinum, in such quantities, at which the value of m is in the range of 0.10-2.50, the careful adding under stirring 5 or 6 drops of concentrated hydrochloric acid, the processing of prepared suspensions by ultrasound during 1,0-5,0 min, dried under vacuum at 105-120oC for 1.5-3.0 hours, oxidative sintering at 300-400oC for 1.0 to 3.0 hours and then reductive sintering at 300-400oC for 1,0-3,0 h with getting ready photocatalyst.

In the process of preparation of the photocatalyst doped with platinum, drying and sintering in an oxidizing/reducing conditions after reaching pH 7 perform for the reason to keep the elementary state of the electron acceptor to knosti CdS and forms a connection with the spin-off's with the formation of PtS, consequently, the sintering process at a temperature of 300-400oC in oxidizing and reducing conditions, a structure is formed of wurtzite. In the case of sintering of the product at a temperature of 300-400oC for 1,0-2,0 h Pt as the electron acceptor can go to the elementary state of Pt(0). In the preferred embodiment, it should sintering at a temperature of 320-380oC. outside this temperature interval lifespan and optical activity of the photocatalyst decreases.

Examples of Cd-containing compounds include CdSO4H2O and Cd(NO3)24H2O, and examples of M-containing compounds include VCl3, VOSO4, VOCl3, K2Cr2O7, Cr(NO3)3, Al(NO3)3, AlCl3H3PO2and so on in Addition, examples of M-containing compounds include RuCl3, Co(NO3)2, CoCl2, Co(CH3COO)2Rh(N3)3, IrCl3,

Ni(NO3)2, NiCl2Pd(NO3)2, CuCl2, Cu(NO3)2, CuSO4and so on

In the patent application in South Korea 96-44214 after the primary sintering is provided by the etching acid, and the present invention is only required stage of drying sludge to the topic and acid etching optional.

In accordance with the present invention, hydrogen is produced by dissolving as 0.15 to 0.40 mol/l Na2S as an electron donor, and 0.20-0.5 mol/l NaH2PO2as the reducing agent in the primary and/or secondary distilled water or just filtered water and add a photocatalyst according to the invention. Next, this suspension is treated with irradiation in the visible region of the spectrum, an adjustable optical filter, or sunlight with stirring at a temperature of 5-85oC and a pressure of 0.1 to 5 atmospheres with high efficiency in the production of hydrogen.

Moreover, an important task is to maintain the concentration of electron donor and reductant in the above-mentioned limits. When it is below the lower limit, the amount of hydrogen decreases; when it is excessive, the amount of hydrogen in the future, may not increase. The most preferred reaction conditions are a temperature of 10-60oC and pressures from vacuum to 2 atmospheres.

If in the reaction environment to re-add the electron donor and the reducing agent, the service life of the photocatalyst according to the invention is unlimited. The duration of the works of well-known ZnS-photocata idunno, 20-25 hours, which means that this photocatalyst is constantly maintained its high level of activity.

THE EXAMPLE I GET

In 250 ml of water CdSO4H2O, K2Cr2O7as a promoter and H2S as a reagent mix to the appearance of the precipitate. The resulting mixture, in which the sediment is a CdMS, mix. The precipitate is washed with water until until the pH of wash water reaches 7. Washed thus precipitate is dried under vacuum in a nitrogen atmosphere at a temperature of 110oC for 2 h, resulting in powder form CdCrS.

RuCl33H2O in this powder is added so that the content of Ru in the sediment was 1 wt%. Next, with stirring, carefully add 5-6 drops of concentrated hydrochloric acid, followed by treatment of the resulting product with ultrasound for 3 min, dried at a temperature of 100oC for 2 h and the oxidizing sintering at a temperature of 350oC for 1.5 h with getting as ready photocatalyst RUO Li2(1,0)/Cd[Cr(0,1)]s

AN EXAMPLE OF RETRIEVING II

Working analogously to example I get, increasing the number of K2Cr2O7with receiving the I except instead of K2Cr2O7as a promoter use Al(NO3)3with getting as ready photocatalyst RUO Li2(1,0)/Cd[Al(0,5)]s

AN EXAMPLE OF OBTAINING IV

Working analogously to example retrieve III except that instead of K2Cr2O7as a promoter use Al(NO3)3with getting as ready photocatalyst RUO Li2(1,0)/Cd[Al(4,76)]s

EXAMPLE OBTAIN V

Working analogously to example obtain II except that instead of K2Cr2O7as a promoter using H3PO2with getting as ready photocatalyst RUO Li2(1,0)/Cd[P(4,76)]s

AN EXAMPLE OF RETRIEVING VI

Working analogously to example obtain V except that after oxidative sintering conduct restorative sintering at a temperature of 350oC for 1.5 h and RuCl33H2O added in a quantity sufficient to achieve the content of Ru in the sediment 1 wt.%, with getting as ready photocatalyst EN(1,0)/Cd[P(4,76)]s

AN EXAMPLE OF RETRIEVING VII

Working analogously to example obtain VI except that instead of RuCl33H2O use NiCl26H2O in totalizator Ni(1,0)/Cd[P(4,76)]s

EXAMPLE OF GETTING VIII

Working analogously to example obtain VI except that instead of H3PO2as a promoter use VCl3with getting as ready photocatalyst Ni(1,0)/Cd[V(4,76)]s

AN EXAMPLE OF RETRIEVING IX

Working analogously to example receiving VII using NiCl26H2O in a quantity sufficient to achieve the Nickel content in the sediment of 0.5 wt.%, obtaining in this way the quality of the finished photocatalyst Ni(0,5)/Cd[P(4,76)]s

AN EXAMPLE OF OBTAINING X

Working analogously to example receiving VII using NiCl26H2O in a quantity sufficient to achieve the Nickel content in the sediment 2.0 wt.%, obtaining in this way the quality of the finished photocatalyst Ni(2,0)/Cd[P(4,76)]s

AN EXAMPLE OF OBTAINING XI

Working analogously to example receiving VII without the process of rehabilitation sintering to produce in the quality of the finished photocatalyst Ni(1,0)/Cd[P(4,76)]s

EXAMPLE XII OBTAINING

Work similarly to example VII obtaining, using Pd(NO3)2instead of NiCl26H2O getting as ready photocatalyst Pd(1,0)/Cd[P(4,76)]s

AN EXAMPLE OF OBTAINING XIII

Work similarly note the 0)/Cd[P(4,76)]s

AN EXAMPLE OF OBTAINING XIV

Work similarly to example XII obtaining, using Rh(NO3)2instead of Pd(NO3)2with getting as ready photocatalyst Rh(1,0)/Cd[P(4,76)]s

AN EXAMPLE OF OBTAINING XV

Work similarly to example XII obtaining, using Co(NO3)2instead of Pd(NO3)2and getting as ready photocatalyst Co(1,0)/Cd[P(4,76)] s

EXAMPLE OF GETTING XVI

Work similarly to example XII obtaining, using IrCl3instead of Pd(NO3)2and getting as ready photocatalyst Ir(1,0)/Cd[P(4,76)] s

WILL GET XVII

To the powder Cd[P(4,76)]S, obtained in accordance with example XVI obtaining, instead of IrCl3type H2PtCl6so that the Pt content in the powder was 0.8 wt%. The finished powder is affected by UV-irradiation (mercury lamp high pressure power 450 W at a distance from the light source to the sample 4 cm) in nitrogen atmosphere for 0.5 h, irradiated thereby precipitate is washed with wash water up until the pH of wash water reaches 7, the washed precipitate is subjected to drying at a temperature of 110oC for 2 h with subsequent oxidative sintering in air PR and 95/5) at a temperature of 350oC for 1.5 h, getting as ready photocatalyst Pt(0,8)/Cd[P(4,76)]s

EXAMPLE OF GETTING XVIII

Working analogously to example getting XVII except that H2PtCl6to the powder is added so that the content of Pt in the sediment was 0.4. %, and thus the quality of the finished photocatalyst get Pt(0,4)/Cd[P(4,76)]s

EXAMPLE OF GETTING XIX

Working analogously to example getting XVII except that H2PtCl6to the precipitate add so that the Pt content in the sediment was 2.0 wt. %, and thus the quality of the finished photocatalyst get Pt(2,0)/Cd[P(4,76)]s

AN EXAMPLE OF RETRIEVING XX

To the powder Cd[P(4,76)]S, obtained in accordance with example obtain V add H2PtCl6so that the Pt content in the powder was 0.8 wt. %. On doped by Pt product (precipitate) are affected by UV-irradiation of a mercury lamp, high pressure power 450 W at a distance from the light source to the sample 4 cm) in nitrogen atmosphere for 0.5 h, the precipitate is washed with wash water up until the pH of wash water reaches 7, rinsed in this way the precipitate is dried under vacuum at a temperature of 110ooC for 2 hours the Dried product is subjected to oxidative sintering at a temperature of 350oC for 1.5 h, getting as ready photocatalyst Pt(0,8)/Cd[P(4,76)]S/RUO Li2(1,0).

EXAMPLE OF GETTING XXI

Working analogously to example getting XX, using NiCl26H2O instead of RuCl33H2O and getting as ready photocatalyst Pt(0,8)/Cd[P(4,76)]S/NiO(1,0).

EXAMPLE OF GETTING XXII

Work similarly to example VII obtaining, using Cu(NO3)2instead of NiCl26H2O and getting as ready photocatalyst Cu(1,0)/Cd[P(4,76)]s

EXAMPLE OF GETTING XXIII

Working analogously to example I get except that the number of K2Cr2O7replace used in the above example so that the Cr content was 25 mol.%, consequently, the quality of the finished photocatalyst get RUO Li2(1,0)/Cd[Cr(25)]s

EXAMPLE XXIV OBTAINING

Working analogously to example receiving the m example so to the Ni content in the product was 3 wt.%, consequently, the quality of the finished photocatalyst get Ni(3,0)/Cd[P(4,76)]s

EXAMPLES I-XXII AND COMPARATIVE EXAMPLES I AND II

0.5 g of photocatalyst prepared in accordance with each of examples obtain I-XXIV, independently from each other are suspended in 500 ml of water, which consists of 0.24 mol/l Na2S and 0.35 mol/l NaH2PO2and prepared, the suspension is stirred at a rotation speed of the stirrer at 300 rpm./min in a photochemical reactor closed gascirculation system. Prepared aqueous suspension is treated with irradiation in the visible region of the spectrum (xenon bulb with power of 500 W with an optical filter that passes light with a wavelength of more than 400 nm, while the distance from the light source to the sample 4 cm) at room temperature and under a pressure of one atmosphere. The amount of hydrogen that is obtained in this way, determined by gas chromatography and by using a burette, indicated in the table.

EXAMPLE XXIII

This experiment allows us to determine the lifetime of the photocatalyst. 0.5 g of photocatalyst prepared in accordance with example XVII obtaining, suspended in 500 ml of water, which includes 0,24 METI cycle 100 hours add an additional 0.24 mol/l Na2S and 0.35 mol/l NaH2PO2determine the amount of hydrogen. Consequently, the average number of received gas at the time of this experiment is 402 ml/h, which is similar (422 ml/h) data of example XVII. Thus, the results achieved in this experiment confirm that the service life of the photocatalyst virtually unlimited (see table).

Industrial applicability

From the above data it is evident that the photocatalyst in accordance with the present invention includes other new alloying metals and various promoters. In addition, the photocatalyst according to the invention exhibits higher optical activity than known photocatalysts, the way of making it easier known methods, and the photocatalyst is characterized by a longer service life and high performance hydrogen.

The present invention, which offers a new photocatalysts obtained by introducing alloying metal elements of different types, ways of their introduction and the various applications of the catalyst, allows not only to eliminate the above-mentioned limitation of activity of the photocatalysts is velichinami expected service life, and performance in hydrogen.

The invention and its advantages are apparent from the above description. It is obvious that the proposed methods and compositions can be made a variety of changes, while staying within the scope of invention. Methods and compositions in the present description is presented only to illustrate preferred embodiments of the invention.

1. CdS - photocatalyst hydrogen following formula:

m(A)/Cd[M(B)]S,

in which m denotes the alloying metal element as an electron acceptor selected from the group including Pt, Ru, Ir, Co, Rh, cu, Pd, Ni, and oxides of these metals;

And indicates the mass percentage of m in the range of 0.10-2,50;

M denotes a catalytic element selected from the group including V, Cr, Al and P;

In means M/(M+Cd) in a molar percentage in the range of 0.05-20,00.

2. Method of preparation of CdS-photocatalyst under item 1, including the dissolution of Cd-containing and M-containing compounds in water, adding under stirring prepared in this way a solution of H2S or Na2S as a reagent to precipitate Cd[M]S, the sediment washing wash water up until the pH UP>C for 1.5 to 3.0 hours, alloying dried thus sediment Cd[M]S by adding thereto liquid m-containing compound in an amount of about 0.10 to 2.50 wt.% and sintering the resulting product.

3. The method according to p. 2, characterized in that the doping also provides UV irradiation.

4. The method according to p. 2, characterized in that the M-containing compound is a compound selected from the group comprising Vl3, VOSO4, VOCl3TO2CR2O7, CR(NO3)3, Al(NO3)3, ll3and H3RHO2.

5. The method according to p. 2, characterized in that the m-containing compound is a compound selected from the group comprising H2PtCl6, Rul3With(NO3)2, l2With(CH3SOO)2, RhCl3Rh(NO3)3, Irl3, Ni(NO3)2, NiCl2Pd(NO3)2, CuCl2C(NO3)2and CuSO4.

6. The method according to p. 2, characterized in that, when m is platinum, alloying provides UV irradiation in a nitrogen atmosphere.

7. The method according to p. 2, characterized in that, when m is platinum, after UV-irradiation doping involves oxidative and reductive cs="ptx2">

9. The method according to p. 2, characterized in that the Cd-containing compounds include CdSO4H2O or Cd(NO3)24H2O.

10. The method according to p. 2, characterized in that, when m is platinum, before drying, add hydrochloric acid.

11. The method of producing hydrogen, which comprises processing with stirring aqueous suspension of photocatalyst radiation in the visible spectrum, an adjustable optical filter, or sunlight, and in which the aqueous suspension comprises 0.15 to 0.40 mol/l Na2S as an electron donor and 0.2-0.5 mol/l NaH2PO2as a reducing agent, characterized in that the used photocatalyst under item 1.

12. The method according to p. 11, characterized in that it comprises the production of hydrogen at a temperature of 10-60oWith under vacuum or pressure up to 2 ATM.

 

Same patents:

The invention relates to installations reformer, namely the setting of the plate type reformer

The invention relates to a device for the partial oxidation using an appropriate catalyst and to a method of partial oxidation

The invention relates to a process for the preparation of catalysts used for chemical transformations in the gas phase, and can be used for the conversion of carbon monoxide with water vapor

The invention relates to a method for joint production of ammonia and methanol

The invention relates to the production of hydrogen by cracking ammonia

The invention relates to the field of organic synthesis, namely, devices and technologies for processing of hydrocarbons into synthesis gas (nH2+ CO) and can be used to obtain a synthesis gas according to the methods of equilibrium, but mostly non-equilibrium partial oxidation pre-mixed gaseous hydrocarbon fuel and oxygen-containing oxidant

The invention relates to the production of catalysts for steam reforming of carbon monoxide in the processes of hydrogen and nitric mixture in the chemical and petrochemical industries

The invention relates to the field of organic synthesis, namely, devices and technologies for processing gaseous hydrocarbons into synthesis gas (nH2+CO) by the method of non-equilibrium partial oxidation of hydrocarbon gas oxygen

The invention relates to the protection of the environment from toxic components of exhaust gases, namely catalytic oxidative purification of hydrocarbon gases

The invention relates to the field of organic chemistry and catalysis, in particular to a method for preparing catalysts for the oligomerization of olefins, C3-C4in various types of gas that can be used in the petrochemical industry, for example in the processing of propane-propylene and butane-butylene fraction cracking

The invention relates to the production of carrier catalysts for processes of refining and petrochemicals, and can be used in the refining and petrochemical industry

The invention relates to catalytic chemistry, in particular to the preparation of catalysts for Hydrotreating of crude oil, and can be used in the refining industry

The invention relates to a process for the preparation of cyanopyridines oxidative ammonolysis of alkylpyridine

The invention relates to the field of inorganic chemistry, in particular to catalysts and methods for their preparation, and can be used in the gas processing industry at facilities Claus

The invention relates to the preparation of heterogeneous catalysts used in hydrogenation processes

The invention relates to the production of catalysts, particularly copper-zinc-aluminum catalysts for low-temperature methanol synthesis and low-temperature conversion of carbon monoxide
Up!