Platinum-containing material preparation method and material

FIELD: precious metal technology.

SUBSTANCE: invention relates to a method for preparation of novel platinum-containing materials, which find always increasing demand in national economy, in particular in heterogeneous catalysis. According to invention, platinum is sublimated on high-temperature glass cloth with preliminarily deposited calcium oxide layer. Thus prepared material is a composite constituted by high-temperature glass cloth with deposited calcium oxide layer bearing (Ca,Si)O2 rods on its surface, said rods having oxidized platinum on their ends and metal particles 3-20 nm in size in underlayer.

EFFECT: enabled preparation of novel platinum-containing material with platinum in finely dispersed state.

7 cl, 1 dwg, 1 tbl, 6 ex

 

The invention relates to a method of obtaining a new platinum-containing materials, which are increasingly used in various fields of national economy. More traditionally, the use of such materials in heterogeneous catalysis.

Platinum catalysts receive, as a rule, by applying platinum to the media. The most important functions of the media are providing high-level condition damage catalytic components and the most complete use of expensive components. This maximizes the dispersion of the catalytically active substances on the surface or in the surface layers of the media.

The most common way of obtaining materials containing precious metals, is a method of impregnation of the carrier with a solution of the corresponding salt of the noble metal with the subsequent stages of drying and heat treatment [Disco VA Bases of methods of preparation of the catalysts. Novosibirsk: Nauka, 1983, 263 S.].

Another way to obtain the synthesis of catalysts, including the consolidation of ORGANOMETALLIC complexes on the surface of the carrier. A feature of these catalysts is the high dispersion, in particular platinum. According to [Ermakov SCI, Kuznetsov B.N., Ryndin Y.A //Kinetics and catalysis, 1973, T, S; Ermakov SCI, Derbeneva, SS, Karakchiev G., Kuznetsov B.N. //Kinetics and catalysis, 1975, T.16., s], the particle size of platinum catalysts, synthesized by Pt(π-C4H7)2/SiO2and restored at 100°With less than 10 Å. When used as a carrier Al2About3the dispersion of metal particles obtained by reduction of surface ORGANOMETALLIC compounds, higher than the catalysts prepared using solutions of hexachloroplatinic acid.

Closest to the proposed method of obtaining a platinum source material is the method of applying platinum fiberglass by impregnating it with ammirata platinum with subsequent stages of drying and heat treatment [RF Patent N2160156, B 01 J 23/56, 21/08].

It is shown [Simonova L.G., Barelko CENTURIES, O. Lapina, Paukshtis E.A. and other Catalysts based on glass-fiber media. I. Physico-chemical properties of silica glass fiber media. //Kinetics and catalysis, 2001, V.42, s; the Patent of the Russian Federation, N2186621, B 01 J 23/56, 21/06, 21/08; Simonova L.G., Barelko CENTURIES, Toktarev AV, Cerasi A.F., Chumachenko V.A., balzhinimaev BS Catalysts based on glass-fiber media. VI. Study of Pt-based catalysts steklotkani media in oxidation reactions of hydrocarbons (propane, n-butane and sulfur dioxide. //Kinetics and catalysis, 2002, T, p.67], h is about steklotkani catalytic systems are effective in many gas-phase and liquid-phase catalytic processes. The total metal content is from 0.03 to 0.55 wt.%. By electron microscopy, high-resolution, it was found that on the outer surface of the catalyst particles of platinum there. All platinum is localized in the volume of the optical fibers, penetrating into them at a depth of 100 Åand particles of platinum so vysokodispersnye that they cannot be observed by the method of transmission electron microscopy. Clusters of platinum up to 10 Å manifest itself only on the high resolution images. However, in some cases presuppose platinum on the surface of optical fibers.

The invention solves the problem of obtaining material containing platinum in a highly dispersed state.

The problem is solved by the method of production, including sublimation of platinum (source of platinum is platinum mesh or highly concentrated platinum composition) at a temperature of 880-950°and pressure of 2-3 ATM in the gas mixture, containing 10-12% vol. ammonia and 14-15% oxygen and served with a bulk velocity of 4-5 l/h, on a substrate constituting the high-temperature fiberglass with a layer of oxide of calcium.

Received platinochloride material is a composition consisting of a high temperature fiberglass with a layer of calcium oxide on the surface of which is formed by the I rods with a diameter of approximately 50 nm and approximately 1000 nm, consisting of (Ca, Si)O2; at the ends of these rods is platinum in the oxidized state, and the layer (Ca, Si)O2in the form of metal particles with sizes ˜5 nm.

The drawing shows electron microscopic picture of the new platinum source material, where a is the substrate of high temperature fiberglass with a layer of oxide of calcium, B - rods, consisting of (Ca, Si)O2at the ends of these rods is platinum in the oxidized state.

Distinctive features of the proposed method to obtain platinum source material are:

1. The deposition of platinum by sublimation of platinum (platinum mesh, highly concentrated platinum songs) when 880-950°and pressure of 2-3 ATM in the gas mixture, containing 10-12% vol. ammonia and 14-15% oxygen and supplied with a bulk velocity of 4-5 l/h

2. The use of high temperature fiberglass with a layer of calcium oxide, obtained by processing high-temperature fiberglass suspension of calcium hydroxide with subsequent stages of drying at room temperature, then in an oven at 110°, 12-14 h and heat treatment at 900°C, 4 h

To assess the possibility of obtaining new platinum source material by sublimation of platinum when 880-950°in the gas mixture containing ammonia and oxygen, wascreated installation of flow-through reactor, made of stainless steel and represents a straight tube. In the tube reactor is inserted sequentially quartz tube insert, which is placed Pt (platinum mesh). Next put a quartz tube insert, which is placed high temperature fiberglass coated with calcium oxide. The reactor is placed inside a high temperature furnace, the temperature of which is controlled by means of thermocouples.

Methods of experimentation: before the beginning of the experiment in the reactor serves helium and install a pressure of 3 ATM and heated in a stream of helium up to 300°C. Then, the reactor serves mixture containing ammonia and oxygen. After that, the reactor set temperature 900°C. At this temperature, platinum and high-temperature fiberglass coated with calcium oxide can withstand a certain time. After the experiment, the reactor is cooled to room temperature in a stream of helium. Unloaded from the reactor materials are weighed and examined for the content of platinum and its state by electron microscopy high resolution.

The advantage of the proposed method is getting a new platinum source material, in which the platinum is in a highly dispersed state and is placed on the surface of the rods formed on the basis of (Ca, Si)O2

The essence of the invention is illustrated by the following examples.

Example 1. 1,36 g high temperature fiberglass (5x5=25 cm2) - SiO2with a specific surface area of 1.8 m2/g is treated with a suspension of calcium hydroxide containing 1 g of Cao, with the subsequent stages of air drying, and then in a drying Cabinet at 110°C for 12 h and heat treatment at 900°C for 4 h the resulting material has a composition, wt.%: 12,5 Cao - 87,5 SiO2and is characterized by a specific surface equal to 2.5 m2/, a portion equal to 0.037 g, treated in the reactor in a stream of a gas mixture containing 10 vol.% ammonia and 14.6% vol. oxygen supplied a rate of 4.5 l/h and passing through the platinum mesh 900°C for 1 h

The content of platinum in the resulting material is shown in the table.

Example 2. Similar to example 1, the difference lies in the fact that the gas mixture containing 11% vol. ammonia and 15 vol.% oxygen supplied a rate of 4.5 l/h and passing through the platinum mesh 880°C for 5 hours

The content of platinum in the resulting material is shown in the table.

Example 3. Analogous to example 2. The difference is that high-temperature glass cloth is treated with a suspension of calcium hydroxide containing 2 g of Cao. The resulting material has a composition, wt.%: 13,5 Cao - 86,5 SiO2.

the contents of the platinum in the resulting material is shown in the table.

Example 4. Similar to example 1. The difference is that high-temperature fabric is treated with a suspension of calcium hydroxide containing 3 g of Cao. The resulting material has a composition, wt.%: 15.3 Cao Is 84.7 SiO2.

The content of platinum in the resulting material is shown in the table.

Example 5. Similar to example 4, the difference lies in the fact that the gas mixture containing 10 vol.% ammonia and 14.6% vol. oxygen supplied a rate of 4.5 l/h and passing through the platinum mesh 900°C for 5 hours

The content of platinum in the resulting material is shown in the table.

Example 6. Similar to example 1. The difference is that high-temperature fabric is treated with a suspension of calcium hydroxide containing 4 g of Cao. The resulting material has a composition, wt.%: 20,8 Cao - 79,2 SiO2.

The content of platinum in the resulting material is shown in the table.

The table presents the results of experiments.

From the above examples and the table shows that the proposed method allows to obtain new platinochloride material, in which the platinum is in a highly dispersed state and is distributed at the ends of the rods formed on the basis of (Sa, Si)O2on the surface of high temperature fiberglass with a layer of oxide of calcium.

Table

The influence of processing on the content of platinum on the surface of high-temperature fiberglass with a layer of calcium oxide
NNThe composition of the substrate, wt.%The duration of treatment, hThe content of Pt at high temperature fiberglass coated with calcium oxide, wt.%
112,5 CaO - 87,5 SiO210,25
250,10
313,5 CaO - 86,5 SiO250,12
415,3 CaO Is 84.7 SiO210,25/0,20*
551,2
620,8 CaO - 79,2 SiO210,25/0,20
* the determination of platinum is carried out with two sides of glass

1. A method of obtaining a platinum source material by depositing platinum on glass, characterized in that the platinum sublimate at high temperature fiberglass with pre-applied layer of oxide of calcium.

2. The method according to claim 1, wherein the calcium oxide is applied at high temperature fiberglass by processing fiberglass suspensie is calcium hydroxide.

3. The method according to claims 1 and 2, characterized in that the platinum sublimate at temperatures 880-950°and pressure of 2-3 ATM in the gas mixture, containing 10-12% vol. ammonia and 14-15% the oxygen.

4. The method according to claim 1, characterized in that the source of platinum is platinum mesh, highly concentrated platinum composition.

5. Material containing platinum and fiberglass, characterized in that it is a composition consisting of a high temperature fiberglass with a layer of calcium oxide, the surface of which is formed rods, consisting of (CA,Si)O2at the ends of which platinum is in the oxidized state, and the layer (Ca,Si)2in the form of metal particles with a size of 3-10 nm.

6. The material according to claim 5, characterized in that the content of platinum is 0.1-1.2 wt.%.

7. The material according to claim 5, characterized in that the content of calcium oxide is of 10.0 to 25.0 wt.%.



 

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