GB2254320A - Granulated inorganic sorbent and method of obtaining it - Google Patents

Abstract

A granulated inorganic sorbent having the following formula: TixZrySn1-x-yO2.nH2O where O<x+y<1, x=0-0.95, y=0-0.15, n=0.05-1.8, and having a specific surface of 30-250 m<2>/g, which is a solid solution of a rutile structure characterized, at an angle of 20 DEG , by the main peaks equal to 26.8+/-0.7, 34.5+/-1.5, 52.8+/-1.5 grades. The method provides for electrolysis of an aqueous solution containing tin chloride, titanium chloride and/or zirconium chloride in a molar ratio of Ti:Zr:Sn=(0-0.95):(0-0.15):(0.03-1), for drop dispersion of the sol obtained into a gel producing a liquid with a pH >/= 12 and for heat treatment of gel particles at a temperature of 20-900 DEG C.

Description

GRANULATED INORGANIC SORBENT AND METHOD OF ITS MANUFACTURE Technical Field The present invention relates to inorganic materials intended for use in high-temperature technological processes and, more particularly, to-a granulated inorganic sorbent and method of its manufacture.

Prior Art All granulated sorbents are characterized, depending on their purpose, by the following performance properties: mechanical strength of the grain (granule), thermal stability, chemical and radiation stability, specific surface and sorption capacity.

Carrying out of various technological processes in gas and liquid streams at elevated temperatures and pressures, and under aggressive media conditions (for instance, heterogeneous catalysis, adsorption and separation of gases, purification of uncooled aqueous condesates and heat-transfer, media at nuclear power plants) stipulates the use of granulated inorganic sorbents possessing a developed active surface, featuring a high chemical and thermal stability, in specific cases also an adequate radiation stability, and good strength characteristics under different service conditions thereof.

Known in technological practice of processing gas and liquid streams are sorbents based on.activated.carbon.

For example, this sorbent is used directly in a flow of argon at a temperature of 150-- 180 OC for-separating kripton and xenon; if modified with a solution of AlCuCl4 it is used for recovering carbon monoxide at a temperature of 100 OC, and if modified with oxine or its derivatives, for purification of heat-transfer media of a nuclear reactor at temperatures up to 150 OC (EP, 3, 0061924). The range of application of sorbents of this type is limited, in gas streams, by their thermal stability which does not exceed 300 - 350 OC in air and, in high-temperature aqueous streams, by moderate chemical and mechanical stability of the base resulting In contamination of the stream with products of destruction.

Besides, these sorbents are characterized by low radiation stability when used in an environment with a high level of ionizing radiation.

Also known in the art are inorganic sorbents based on oxides of multivalent metals possessing high thermal and radiation stability, a large specific surface and high adsorption capacity. Essentially, these are the sorbents based on aluminium oxide, silicon dioxide, and also titanium dioxide which additionally contaIns oxides of aluminium, iron, silicon, anions of inorganic scids (sulfuric, hydrochloric, phosphoric). and also sodium titanate with a composition of NaTlO H These sorbents are used predominantly for the purification of high -temperature water streams from ions of metals contained in corrosion products, and from radiactive isotopes.

The above-mentioned oxide sorbents are characterized by low chemical stability in aqueous streams at high pressures and temperatures with the result that deleterious technological impurities (aluminium, silicon, chlorine, phosphorus, sulfur, sodium) are eluated out of sorbent into the liquid phase, this reducing the efficiency of the technological process. In particular, in the production of pure substances or water, this results in deterioration of final product quality, and in nuclear power engineering, in the purification of uncooled aqueous heat -transfer medium, this accelerates corrosion of lines, formation of deposits on reactor fuel elements and increase of radiation background.

For.service in high-temperature aqueous streams, it was proposed to use thermostable hydrated oxides of metals belonging to the IV group of Periodic System possessing high chemical and radiation stability: TiO2 (US, A, 4268422); TiO2, ZrO2, SnO2 (JP, A, 5C-133694); TiO2, SnO2 (JP, A, 58-51640), and also titanium dioxide deposited on titanium sponge.(US, A, 4587232).

These sorbents have a low hydrothermal stability in water at a temperature above 100 C. This is associated with the fact that, under hydrothermal conditions, crystallization processes and phase transformations proceed intensively in said sorbents, this causing fracture of the granules and entrainment of the sorbent by the filtrate.

Amorphous hydtated oxides of titanium, zirconium and tin, when subjected to heat treatment in air, undergo the following phase transformations:

TiO2: amorphous 350-400 C rutile phase anatase modificat- ion (Izvestia Akademii nauk SSSR.Moscow: Neorganicheskie Materialy, 1983, Vol.19, No. 7 /Malykh T.G. et al. "Vliyanie temperatury gidrotermalnoi obrabotki na poristuyu strukturu i mekhanicheskuyu prochnost sorbenta na osnove granulirovannogo dioxida tatana", pp.1215-1217);

ZrO amorphous 300-3500C monoclinic 900 C tetra 2 phase phase gonal phase (Kolloidny Zhurnal, Moscow, 1983, Vol.45, Issue 3 / Sharygin L.M. et al. "Gidrotermalnaya ustoichivost gidratirovannoi dvuokisi tsirkonia", pp.608-611);

amorphous 400 C SnO2: cassiterite (of rutile type) phase (Journal "Kinetika i Kataliz", 1975, Vol.16, No. 6 / Sharygin L.M. et al. "Gidrotermalnoe modifitsirovanie poristoi struktury gidratirovannoi dvuokisi olova", pp. 1056-1061. - Hydrothermal modification of the porous of hydrated stannic oxide).

As has been established, under hydrothermal conditions at a temperature of water of 150 - 350 C the specific surface and the mechanical strength of the granules of amorphous oxides of zirconium, titanium and tin sharply drops as a result of chemical and phase transformations of the sorbent, the phase transformation of the initial amorphous matrix starting at a much lower temperature than in the case of heat treatment in air.

For example, in the process of hydrothermal heat treatment hydrated oxide of zirconium, amorphous according to X-ray diffraction analysis, starts to be transformed into the metastable tetragonal modification already at the temperature of water of 160 OC, and at 350 C the transition of the latter into stable monoclinic phase is practically completed in eight days. As a result, in such transformation internal stresses arise in the primary particles of hydrated oxides of titanium, zirconium, and tin which leads to their deaggregation and, as a consequence, to mechanical destruction of the sorbent granules in the process of filtration and to pollution of the high-temperature aqueous stream with the products of destruction thereof.

Known in the art is an inorganic granulated sorbent on the basis of oxides and partly hydrated oxides of metals, having a composition (US, A, 4661282) [(Ti, Zr, Sn)x(Al, Fe, Cr; Ga, Co; Re, In)1 xOy(OH)z] (A-1)d(A-2)e(A-3)f(A-4)g.nH2O where A is an anion with negative valence 1, 2, 3, 4, respectively; y # z 0 < x < 0.5 O < d + 2e + 3f + 4g z x O s n s 10 .

The sorbent is produced by co-precipitating salts of two metals in an aqueous medium at constant pH, this being followed by drying the resultant gel at a temperature lower than 150 OC, treating it with an acid (H3P04, H2S04) and roasting thereof at a temperature of 160 800 OC. With such a method of producing the sorbent, the latter, even after drying at the temperature of 125 bC, has a structure amorphous in terms of the X-ray diffraction analysis, comprising a mixed chemical composition of the hydroxides of two metals, of which one is titanium, zirconium or tin, an anionic acid residue, and water.

The sorbent has thermal and chemical stability at elevated temperatures (above 160 OC) and a considerable anion-exchanging capacity.

This sorbent, however, is characterized by insufficient chemical stability because of the presence in its composition of anions and metals with positive valence equal to three or five.

If the sorbent is used in the system of purification of non-cooled heat carrier of atomic e-lectric power stations, the anions and said cat ions will be washed out of the sorbent, contaminating the filtrate with undesirable admixtures. The sorbent is noted for a low stability of its strength and structural-sorption characteristics, the cause thereof being in.the crystallization processes and phase transitions occurring in the water at elevated temperatures. Such sorbent has short service life and is not reliable in operation.

Disclosure of the Invention It is an object of the present invention to provide a granulated inorganic sorbent with an ordered crystalline structure on the basis of oxides of metals belonging to group IV of the Periodic System, with improved strength and structural-sorption characteristics at elevated temperatures and pressures, characterized by stability in prolonged service under said conditions, and also to provide a method of producing said sorbent by employing electrochemical technology ensuring a prescribed crystalline structure and the desired combination of physico-chemical properties.

Said object is accomplished by that proposed herein is a granulated inorganic sorbent on the basis of oxides of metals belonging to group IV of the Periodic System which, according to the invention, has the formula: TixZrySn1-x-yO2.nH2O where O < x + y < 1; x = O - 0.95; y = 0 - 0.15; n = 0.05 - 1.8, having a specific surface of 30 - 250 m2/g and representing a solid solution with a rutile type structure, and with X-ray diffractogram, as measured using Cu-K ation, characterized by principal peaks at the angle 2S equal to 26.8+0.7, 34.5+1.5, 52.8+1.5 degrees.

The sorbent produced in accordance with the method of the invention is characterized by a considerable increase of the chemical and thermal stability in liquid and gas streams at a temperature of 150 - 900 C and elevated pressure and, as a consequence, by an increase of its service life and also by a reliability in oparation. The sorbent us noted for a high sorption and catalytic activity due to the developed surface thereof.

An increase of the content of titanium dioxide to more than 95 mole % leads to the appearance of anatase modification, whereas the content of zirconium dioxide exceeding 15 mole % contributes to the formation of the monoclinic phase.

In both cases the hydrothermal stability of the sorbent in high-temperature aqueous streams drop down sharply.

The upper linit of water content in the formula (n = 1.8) is conditioned by a reduction in the strength of the granules of the desired product; the lower limit (n = 0.05) is conditioned by the lowering of the sorption activity of the sorbent because of the low concentration of hydroxyl groups on the surface thereof.

A necessary condition for maintaining the required composition of the sorbent is the presence of tin dioxide whose content is varied within 3 - 98 mole %, depending on the ratio of titanium and zirconium dioxides. Varying the content of these three components is dictated by the required properties of the sorbent, depending on the purpose and service conditions thereof.

Proposed herein is a sorbent which, according to the invention, has the following formula Ti On nH2 Zr where x = 0.05 - 0.4; y = 0.02 - 0.15; n = 0.05 - 1.8, possessing a structure with an X-ray diffractogram characterized by principal peaks at the angle 26 equal to 26.8+0.4, 34+0.9, 52,2+0.8 degrees.

A sorbent of such composition possesses an increased adsorption and catalytic activity in high-temperature team-gas and gaseous streams containing radioactive iodine and its organic derivatives, and can be used as well for neutralizing exhaust gases containing carbon monoxide, and in catalysis.

Proposed herein also is a sorbent which, according to the invention, has the following formula xZrySn1-x-yO2.nH2O where x = 0.4 - 0.95; y = 0.02 - 0.15; n = 0.05 - 1.8, possessing a structure with an X-ray diffractogram characterized by principal peaks at the angle 20 equal to 26.8+0.4, 35.2+0.9, 53.5+0.8 degrees. A sorbent of such composition has an increased sorption capacity with relation to uranium. It can be useful for decontamination of steam-gas emissions at nuclear plants and also for recovering uranium from solutions with complex combination of salts.

Proposed herein also is a sorbent which, according to the invention, has the following formula tixSn1-o2 n O where x = 0.05 - 0.9; n = 0.05 - 1.8, possessing a structure with an X-ray diffractogram characterized by principal peaks at the angle 26 equal to 26.8+0.7, 34.5+1.5, 52.8+1.5 degrees.

Such a sorbent features an increased sorption capa- city relative to ions of metals contained in corrosion products (iron, cobalt, nickel), or of toxic metals (lead, copper) and can be useful in a variety of techo- logical processes which are conducted under common conditions or at elevated temperatures and pressures. The sorbent can be used in processing radioactive wastes and in cleaning steam-gas streams from organic derivatives of radioactive iodine.

Proposed herein also is a sorbent which, according to the invention, has the following formula ZrySn1 -y02 .nH2O where y = 0.02 - 0.15; n = 0.05 - 1.8, possessing a structure with an X-ray diffractogram characterized by principal peals at the angle 2# equal to 26.2+0.05, 33.1+0.05, 51 .4+0.05 degrees. This sorbent features a high chemical resistance and strength. It can be used as an efficient collector for removing microcomponents, both in ion and colloid form, from high-temperature aqueous streams, for instance, uncooled heat transfer medium of a nuclear reactor, as well as from various process solutions. It can b used in various catalytic processes (both individually and as a carrier), in radiochemical industry, in processing high-radioactive waste and for decontamination of gas emissions containing radioactive iodine.

It is expedient that the surface of the sorbent should be modified by at least one element selected from one of groups I, II, III, V, VI, VII, VIII of the Periodic System, the amount of the said element being within 0.0005 - 1.5 mmole/g.

Modification extends the applicability of the said sorbent owing to increased adsorption and catalytic activity at high temperatures not only in gaseous and steam-gas streams, but also in organic and aqueous media.

In order to achieve good hydraulic and dynamic cha- racteristics, it is advisable that the sorbent granules should have a shape close to spherical one, and possess fracture limit of at least 50 kgf/cm and size within 0.001 to 3 mm.

The object is accomplished also by that proposed herein is a process for producing a granulated inorganic sorbent on the basis of oxides of metals belonging to group IV of the Periodic System in which, according to the invention, an aqueous solution containing tin chlor lae and at least one chloride of a metal selected from the group consisting of titanium and zirconium, at the molar ratio of Ti:Zr:Sn = (0 - 0,95):(0 - 0.15)::(0.03-I,O), is subjected to electrolysis till the atomic ratio of chlorine to the metal becomes 0.2 - 1X)ensuring the formation of a mixed sol of the hydrated oxides of metals, followed by dropwise dispersing of said sol in a gelating liquid with pH a 12, separating of the formed gel particles which are then washed and subjected to heat treatment at a temperature within 20 to 900 OC yielding granules of the desired product complying with the formula TixZrySn where O < x + y < 1; x = 0 - 0.95; y 2 0 - 0.15;; n = 0.05 - 1.8, having a specific surface of 30 - 250 m2/g and representing a solid solution of a rutile type structure, and with X-ray diffractogram, as measured using Cu-K i-radi- ation, characterized by principal peaks at the angle 29 equal to 26.8+0.7, 34.5+1,5, 52.8+1.5 degrees.

The method proposed herein, due to an appropriate selection of the parameters of the electrochemical process of producing a crystalline sol and the process of sol granulation in a gelating liquid, and also due to the combination of these stages in one technological cycle, ensures the formation of an ordered crystalline structure of a solid solution in the gel particles prior to the heat treatment stage, this being unattainable in any of the known methods of precipitation.

The method of the invention is adaptable to streamlined production and easy to realize, it makes possible the obviation of the long-time stages of precipitation, filtering of the gel, and comminution thereof. One technological operation (dispersing of the sol) enables the production of granules having the required fractional composition, washing off of the gel particles being carried out with a considerably smaller consumption of washing water.

Depending on the requirements to be met by the sorbent, it is recommendable that the aqueous solution subjected to electrolysis should contain: chlorides of titanium, zirconium and tin at the molar ratio thereof of (0.05-0.4):(0.02-1 .15):(0.43-0.95), respectively, or chlorides of titanium, zirconium and tin at the molar ratio thereof of (O.4-0.95):(0.O2-0.15):(0.O3-0.45), respectively, or chlorides of titanium and tin at the molar ratio thereof of (O.05-0.9):(0.1-0.95), respectively, or chlorides of zirconium and tin at the molar ratio thereof of (0.02-0,15):(0,85-0.98), respectively.

The electrolysis of the latter solution is carried out till the atomic ratio of chlorine to the metal becomes 0.5 - 1.0.

In the course of the electrolysis hydrochloric acid is removed from the solution by way of decomposition of the hydrochloric acid at the electrodes into chlorine and hydrogen. As a result of the removal of the hydrochloric acid, the atomic ratio of Cl/Me, which in the initial solution of the chlorides reaches the value r"4, becomes diminished, there occur hydrolysis, polymerization, oxolation of the abovesaid metals, and at Cl/Me - < 1 there is formed an anion-deficient colloidal solution (sol) of hydrated oxides of metals with the structure of colloidal particles on the basis of the crystalline solid solution of the oxides of these metals. Lowering of the ratio Cl/Me 4 0.2 involves technical difficulties because of a high liability of the synthesized sol to spontaneously gelate in the electrolytic cell.The resulting anion-deficient sol is dispersed dropwise into a gelating liquid, an aqueous solution of an alkali or of ammonia with pH - 12 being preferably used as--such liquid. At a lower pH value, the mechanical strength of the gel particles and granules of the desired product is reduced markedly. The gel particles are separated from the mother liquor, washed with water, and subjected to heat treatment at 20 - 900 OC. Such temperature conditions ensure the production of partially hydrated oxides of said metals. It is desirable that the solution to be subjected to electrolysis should have the total concentration of metal chlorides from 0.3 to 3 mole/litre.A concentration of the metal chlorides less than 0,3 mole/ /litre yields, at the stage of gelation, particles with small mechanical strength which become deformed or fractured in the process of further treatment, lowering the yield of the finished product. The production of a sol when the total. concentration.of the metal chlorides is greater than 3 mole/litre involves technological difficulties: the processes of hydrolysis go slowly, while membranes quickly become inoperative because of a high acidity of the electrolyte.The optimal range of temperatures for carrying out the electrolysis is 10 80 OC, The upper temperature limit is defined by the thermal stability of the cation-exchange and anion- -exchange membranes which are destroyed at a temperature above 80 OC. The lower temperature limit is conditioned by the low rate of hydrolysis of the metal chlorides, this restricting the efficiency of the electrolytic cell.

The electrolysis is carried out at current densities not exceeding the limit values for the membranes of both types.

For extending the potential uses of the sorbent, according to the invention, after the heat treatment it is expedient that the surface thereof should be modified by treating with a 6*10 6 - 1.5 mole/litre solution of at least one salt of an element selected from groups I, II, III, V, VI, VII, VIII of the Periodic System or with at least one hydroxide of R metal selected from group I-II of the Periodic System, this being followed by heat treatment at a temperature of 100 - 900 00.

The concentration of the solution is determined by the effect of modification, while the temperature and duration of the heat treatment depend on the nature of the modifier. The upper limit is determined by the loss of the sorption and catalytic properties of the modified sorbent; the lower limit of the heat treatment is determined by the necessity to remove physically bound ballast water from the sorbent before using thereof.

Preferred Embodiment of the Invention An aqueous solution comprising 0.231 mole/litre of tin chloride, 0.77 mole/litre of titanium chloride and 0.099 mole/litre of zirconium chloride (the molar ratio Sn:Ti:Zr = 0.21:0.7:0.09) is fed to the middle chamber of a three-chamber electrolytic cell, separated from the cathode and anode spaces by corresponding ion-exchange membranes. In the electrolytic -cell the cathode is made of titanium and the anode, of graphite. The electrolysis is carried out at the temperature of 40 OC and membrane current density of 400 A/m2. The electrolysis is discontinued upon reaching the atomic ratio of chlorine to metal equal to 0.55.

The formed sol of hydrated oxides of tin, titanium, zirconium is dispersed dropwise through a glass capillary with an inner diameter of 0.2 mm into an aqueous solution of ammonia with pH 13. The resulting spherical gel particles are separated by filtration and washed with distilled water to remove the electrolyte.

The gel particles thus prepared, according to X-ray spectral analysis, have a structure of rutile type. Then, the particles are subjected to heat treatment at the temperature of 400 OC till spherical granules having a size of 0.2 - 0.4 mm are formed, with the fracture limit of 215 kg/cm. The yield of granulated sorbent is 96 %.

The sorbent has the formula Tio 7ZrO 09SnO 2102 0.27H20, the specific surface thereof is 110 m2/g, and the sorbent is a solid solution having a structure of rutile type, with an X-ray diffractogram measured with the help of CU~Ko-radiatiOn and characterized by main peaks at the angle 26 of 27.O, 35.3 and 53.3 degrees. After 3000 hours of hydrothermal tests carried out in an autoclave at the temperature of 350 C and pressure of water vapours saturated at this temperature, the sorbent has the following characteristics: specific surface, 48 m2/g; fracture limit of the granules, 80 kgf/cm2. Visual observations show complete absence of faulty or fractured granules in the whole lot subjected to the tests; this is a confirmation of good performance characteristics of the sorbent produced.

Other examples of producing a granulated inorganic sorbent, according to the invention, with indication of the physico-chemical and sorption characteristics thereof, are given hereinbelow.

Example 1 An aqueous solution containing 0.3 mole/litre of TiCl4, 0.08 mole/litre of ZrOCl2 and 1.12 mole/litre of SnC14 with a total concentration of 1 .5 mole/litre (the molar ratio Ti:Zr:Sn = 0,20:0.05:0.75) is fed to the middle chamber of-a three-chamber electrolytic cell, separated from the cathode space and from the anode space by corresponding ion-exchange membranes. A 0.1 mole/litre solution of hydrochloric acid is fed to the cathode and anode chambers of the electrolytic cell.

The electrodes are made of materials resistant to hydrochloric acid and chlorine: the anode is made of graphite and she cathode is made of titanium. The electrolysis is carried out at the membrane current density.of 300 A/m2 and at the temperature of 35 CC. The electrolysis yields a time-stable mixed sol with the atomic ratio Cl/Me = 0,5.

The resulting mixed sol is dispergated dropwise into an aqueous solution of ammonia with pH 13.

The gel particles are washed off from the electrolyte with distilled water and divided into three lots.

Tne first lot of the gel is thermostated at the temperature of 20 OC, This gives granules having a shape close to the spherical one and a diameter of 0.1 - 0.5 mm. The second and third lots are subjected to heat treatment at the temperatures of 400 and 900 OC, respectively. The resulting granulated sorbent has the formula Ti0.2Zr0.05Sn0.75O2.nH2O where n- 3 1.8, 0.3, 0.05, respectively, at the heat treatment temperatures of 20, 400 and 900 OC.

Given hereinbelow, in Table 1, are Examples 2-15 of producing the sorbents of the formula TixZrySn1-x-yO2.nH2O with indication of the parameters of their electrochemical synthesis, carried out as described in Example 1.

Table 1 Initial aqueous solution Exam- Total concentrat- Molar ratio of metal chlorides ple ion of metal No. chloride, Ti Zr Sn mole/litre 1 2 3 4 5 2 1.5 0.05 0.02 0.93 3 1.5 0.20 0.15 0.65 4 1.5 0.40 0.05 0.55 5 1.5 0.40 0.15 0.45 6 1.5 0.40 0.01 0.59 7 1.1 0.35 0.15 0.50 8 1.1 0.40 0.15 0.45 9 1,1 0.50 0.09 0.1 10 1.1 0.70 0.09 0.21 11 0.3 0.70 0.09 0,21 12 3.0 0.70 0.09 0.21 13 1 .1 0.70 0.09 0.21 14 1.1 0.87 0.10 0.03 15 1 .1 0.95 0.02 0.03 For studying the micro- and macrostructure of the sorbents, as well as the properties thereof, X-ray crys tallographic analysis (XRCA) is used.X-ray crystallo graphic studies are carried out in a diffractometer with the use of CU-KC-radiation. The specific surface of the sorbents is calculated from the data on low-temperature adsorption of nitrogen by the BET method. The fracture limit is assessed by the method of crushing the granules between two rigid supports. An average value of the fracture limit is calculated as a result of testing 20 granules. The measuring error is 12 -- 18 %.

Hydrothermal treatment of the sorbents is carried out in stainless steel autoclaves under 9tatic-conditions at the temperature of 350 OC and under a pressure equal to the pressure of saturated water vapours at the given temperature, 15 ml of a sample being placed into the auto- crave. The hydrothermal stability is assessed by the time Table 1 (continued) Exam- Temperature of Atomic ratio XRCA data of ple electrolysis Cl/Me in sol sol (type of No. process, OC lattice) 1 6 7 8 2 15 0,8 Rutile type 3 35 0.4 Item 4 30 0,25 Item- 5 30 0.2 Item 6 25 0.3 Item 7 40 0.55 Item 8 40 0.55 Item 9 40 0.55 Item 10 40 0.55 Item 11 80 0.20 Item 12 20 1.0 Item 13 10 0.55 Item 14 40 0.55 Item 15 40 0.55 Item of hydrothermal treatment till fracture.In the course of the treatment samples of the sorbents are taken after definite periods of time for measuring the specific surface. The material is considered to be destroyed, if its specific surface is 30 m2/g. After 3000 hours of treatment the samples of the sorbents are discharged and the phase composition of the material, its strength and specific surface are determined again.

The sorption capacity of the sorbent for uranium (aU) is determined in a solution imitating sea water with the initial pH value of 7.8 at room temperature. To this end, 200 mg of the sorbent dried at 125 OC are brought in contact under stirring with 20 ml of an imitation solution that contains uranium in the concentration of 1 mg/litre.

In a week the sorbent is separated from the liquid phase, washed with distilled water from the mother liquor-and analyzed for uranium with the help of neutron-activation analysis.

The compositions and properties of the granulated sorbents obtained as described in Examples 1-15, under different heat treatment conditions, are given in Table 2 hereinbelow.

Table 2 Exam- Composition of sorbent Properties of sorbent after ple heat treatment at 20 C No.

n S, #m, XRCA data: m type of m/g kgf lattice, main cm peaks at the angle 2#, degree 1 2 34 5 6 1 Ti0.2Zr0.05Sn0.75O2.nH2O 1.8 230 190 Rutile type 26.7; 34.3; 52.4 2 Ti0.05Zr0.02Sn0.93O2.nH2O 1.8 200 200 Item, 26.4; 33.6; 51.8 3 Ti0.2Zr0.15Sn0.65O2.nH2O 1.8 240 190 Item, 26.7; 34.3; 52.4 4 Ti0.4Zr0.05Sn0.55C2.nH2O 1.8 240 300 Item, 27.0; 34.5; 52.7 5 Ti0.4Zr0.15Sn0.45O2.nH2O 1.8 246 260 Item, 27.0; 34.6; $52.7 6 Ti0.4Zr0.01Sn0.59O2.nH2O 1.8 220 200 Item, 27.0; 34.5; 52.8 7 Ti0.35Zr0.15Sn0.5O2.nH2O 1.8 250 110 Item, 26.8; 34.4; 52.6 Ti0.40Zr0.15Sn0.45O2.nH2O 1.8 246 100 Item, 27.0; 34.5; 52.7 g Ti0.50Zr0.09Sn0.41O2.nH2O 1.8 245 105 Item, 34.7; 52.7 10 Ti0.70Zr0.09Sn0.21O2.nH2O 1.8 248 100 Item, 27;0; 35.3; 52.3 11 Ti0.70Zr0.09Sn0.21O2.nH2O 1.8 240 100 Item, 27.0; 35.3; 53.3 12 Ti0.70Zr0.09Sn0.21O2.nH2O 1.8 230 130 Item, 27.0; 35.3; 53.3 13 Ti0.70Zr0.09Sn0.21O2.nH2O 1.8 250 100 Item, 27.0; 35.3; 53.3 14 Ti0.87Zr0.10Sn0.03O2.nH2O 1.8 246 105 Item, 27.0; 35.5; 53.6 15 Ti0.95Zr0.02Sn0.03O3.nH2O 1.8 250 190 Item, 27.0; 35.8; 53.8 Table 2 (continued) Exam- Properties of sorbent after heat treatment at ple No. 125 C 400 C &alpha;u n S, mole/g m/g 1 7 8 9 10 1 - 0.27 90 400 2 - 0.27 80 450 3 - 0.26 96 380 4 - 0.25 110 660 5 - 0.26 105 600 6 - 0.26 80 320 7 5.0 0.26 102 210 8 5.7 0,26 105 200 9 7.0 0.25 108 205 10 9.7 0.27 112 210 11 9.8 0.26 103 160 12 9.7 0.25 108 250 13 9.6 0.28 110 215 14 12.2 0.26 115 170 15 13.3 0.27 117 150 Table 2 (continued) Exam- Properties of sorbent after heat treatment at 4000C ple No.After hydrothermal treatment Stability, XRCA data: type of S, #m, hrs lattice, main peaks at the angle 2 #, m/g kgf/cm degree 1 11 12 13 14 1 over 3000 Rutile type 50 100 26.7; 34.3; 52.4 2 over 1600 Item 26 70 26.4; 33.6; 51.8 3 over 3000 Item 47 100 26.7; 34.3; 52.4 4 over 3000 Item 52 110 27.0; 34.5; 52.7 5 over 3000 Item 49 100 27.0; 34.5; 52.7 6 over 3000 Item 46 100 27.0; 34.5; 52.8 7 over 3000 Item 40 80 26.8; 34,3; 42.6 8 over 3000 Item 42 80 26.8; 34.3; 52.6 9 over 3000 Item 44 80 27.0; 34.7; 52.7 10 over 3000 Item 48 80 27.0; 35.3; 53.3 11 over 3000 Item 46 60 27.0; 35.3; 53.3 12 over 3000 Item 50 100 27.0; 35.3; 53.3 13 over 3000 Item 48 80 27.0; 35.3; 53.3 14 over 3000 Item 49 70 27.0; 35.5; 53.6 15 over 1800 Item 45 50 27.0; 35.8; 53.8 Table 2 (continued) Exam- Properties of sorbent after heat treatment at 9000C ple No. n main XRCA data: type of lattice, main peaks at the angle 2# m/G kgf/cm degree 1 15 16 17 18 1 0.05 32 180 Rutile type 26.7; 34.3; 52.4 2 0.05 30 210 Item, 26.4; 33.6; 51.8 3 0.05 35 180 Item, 25.7; 34.3; 52.4 4 0.05 38 280 Item, 27.0; 34.5; 52.7 5 0.05 38 260 Item, 27.0; 34.3; 52.7 6 0,05 26 260 Item, 27.0; 34.5; 52,7 7 0.05 30 175 Item, 26.8; 34.3; 52.6 8 0.05 32 165 Item, 27.0; 34.5; 52.7 9 0.05 35 170 Item, 27.0; 34.7; 52.7 10 0.05 35 170 Item, 27.0; 34.7; 52.7 11 0.05 30 150 Item, 27.0; 35.3; 53.3 12 0.05 34 240 Item, 27.0; 35.3; 53.3 13 0.05 35 170 Item, 27.0; 35.3; 53.3 14 0.05 30 160 Item, 27.0; 35.5; 53.6 15 0.05 30 145 Item, 27.0; 35.8; 53.8 From Table 2 it follows that the sorbent proposed herein, based on the oxides and partially hydrated oxides of titanium, zirconium and tin, has good strength and thermochemical properties. Possessing a high strength, the sorbent, though its properties are lowered in the process of hydrothermal tests, retains its efficiency in the range of optimal composition, as regards its specific surface, hydrothermal stability (the service life being 1600 hrs and more), and chemical stability.Furthermore, from Table -2 it is seen that the sorbent with the structure of rutile type of the formula TixZrySn1-x-yO2.nH2O where x = 0.40 - 0.95, y = 0.02 - 0.15, n = 1.8 (Examples 1 - 6), possesses sorption capacity for uranium, which feature may be put to advantage in hydrometallurgy for selective recovery of this metal from sea water, natural water and process solutions. The chemical analysis of water after the whole range of autoclave tests, carried out for all samples, demonstrated that the content of titanium, tin and zirconium in the filtrate was below the detection threshold (1,ug/litre).

Example 16 To carry out modification, a batch of 1 g of the sorbent Ti Zrg.0,Sn,.5502 1.8H20, prepared in accordance with Example 4 of Table 2, heat treated at 20 OC, is brought in contact with 100 ml of a solution of a metal salt or base and kept under stirring for five days.

In some cases for increasing the modifier content in the solid phase, the working solution is neutralized by the introduction of additives of sodium, potassium or ammonium hydroxides. On completion of keeping, the solid and liquid phases are separated, and the quantity of metal absorbed by the sorbent is calculated from the decrement in the metal concentration in he solution. An analysis of the liquid phase for the content of alkali metals, cadmium, lead, bismuth is carried out by the method of complexonometric titration; an analysis for the content of silver, manganese is carried out radiometrically, with the use of 54E, 110mAg isotopes; an analysis for the content of copper and iron is carried out by the method of acidometric titration. The sorbent is washed and dried at 100 C. The capacity for methyl iodide is determined under static conditions in an autoclave at 150 OC.A 1 g batch of the sorbent is charged into an autoclave, methyl iodide vapours labelled with 131I radionuclide are admitted there into, and the mixture is kept under thermostatted conditions for 24 hours. After cooling the sorbent is analyzed by the method of gamma -spectrometry for the content of methyl iodide, and the sorption capacity of the sorbent for methyl iodide (&alpha;CH3) is calculated.

Table 3 lists the sorption capacity characteristics of said sorbent, modified by different cations.

As is seen from the results of tests (Table 3), modification of the sorbent of the invention with the modifier content of 0.1 - 1.5 mole/g gives an additional increase of the sorption capacity of the sorbent with respect to organic iodine compounds from the gaseous phase.

Furthermore, Table 3 also illustrates the sorption capacity of the sorbent when cations of different metals are recovered from aqueous solutions (0.09 - 1.52 mole/g).

Example 17 To carry out modification, a batch of 1 g of the sorbent Ti0.70Zr0.09Sn0.21O2.1.8H2O, prepared as described ed in Example 10 (Table 2) and heat treated at the temperature of 20 OC, is contacted with 100 ml of a working solution of a metal salt or base and kept under stirring for five days. In some cases, for increasing the content of the modifier cations in the solid phase, the working solution is neutralized by introducing additives of sodium, potassium or ammonium hydroxides. On completion of keeping, the solid and liquid phases are separated, and the quantity of metal cation absorbed by the sorbent is calculated from the decrement of the metal concentration in the solution.An analysis of the liquid.phase for the content of alkali metals, cadmium, lead, bismuth, yttrium, lanthanum, cerium, cobalt, nickel is carried out by the method of complexonometric titration with complexone III; for the content of zinc, chromium, silver and manganese, radiometrically, with the use of 65Zn, 51Cr, 11OmAg and 54Mn isotopes; for the content of copper, vanadium, antimony and iron, by the method of Table 3 Exam- Solution of modifier Content of &alpha;CH3I, ple modifier in mg/g No.Composition Absorbed Concentra- sorbent, cation tion, mole/litre mole/litre 1 LiOH Li+ 0.1 0.09 15 2 NaN03 Na+ 0.5 0.35 42 3 KOH K+ 0.4 0.29 55 4 RbN03 Rb+ 0.6 0.38 60 5 CsN03 Cs+ 1.2 0.36 97 6 Cu(NH3)4Cl2 Cu2+ 0.1 0.17 31 7 AgN03 Ag+ 0.1 0.21 85 8 Cd(N03)2 Cd2+ 0.5 0.70 42 9 3i(N03)3 in Bi3+ 0.1 0.28 0.5 mole/ /litre HNO3 10 Fe(NO3)3 Fe3+ 0.1 0.25 21 11 MnS04 Mn2+ 0.5 0.93 45 12 Pb(N03)2 Pb2+ 0.01 0.1 20 13 Pb(N03)2 Pb2+ 0.1 0.68 122 14 Pb(NO3)2 Pb2+ 0.5 1.52 156 Is NaOH+CsOH Na++Cs+ 0.1+0.1 0.18+0.20 58 acidimetric titration. The sorbent is washed with water and dried at 100 OC.

To determine the sorbent capacity for the I ion in an aqueous solution, a batch of 1 g is placed into 50 ml of a 0.1 mole/litre solution of NH4I and kept for 24 hours. On completion of keeping, the sorbent is separat ed from the solution, washed with eater, eluted with 1 mole/litre of tTaOH and analyzed by the method of back argentometric titration.

For the determination of the sorbent capacity for iodine (&alpha;I2) in the gaseous phase, a batch of the sorbent is placed into an autoclave, heated to the temperature of 110 OC, then the autoclave is evacuated to the pressure of 0.01 mm Hg, and then the iodine vapours are discharged till complete saturation of the sorbent. The sorbent is kept in contact with the iodine vapours for 20 hours, then the iodine is evacuated to the pressure of 0.01 mm Hg. The content of iodine in the sorbent is determined as described above.

The data on the sorption capacity of said sorbent, modified with ions of different elements, are presented in Table 4.

Table 4 demonstrates that the sorbent of the proposed composition after modification effectively remove iodine from aqueous and gaseous media. 3esides, the data on modifier concentration in the sorbent show marked sorption capacity of the sorbent in relation to a number of toxic elements (lead, bismuth, antimony, cadmium, barium) in aqueous and organic media: 0.56 - 1.52 mole/g.

Example 18 The activity of work of the granulated sorbent as a catalyst was assessed in a gaseous mixture, having a composition (vol. %): 0.28 CO 0.15 02 the balance being argon.

To do that, a modified sample of the sorbent DiO.4ZrO.1 5Sno.45 2 0.26H20 (Table 2, Example 5), heat-treated at the temperature of 400 OC, is charged into a thermostatted column, having an inner diameter of 14 mm. The height of the charge is 40 mm. The surface of said sorbent is modified as in Example 16. After modification, the samples of the sorbent Table 4 Exam- Solution of modifier Content &alpha;I2 mg-equiv./g ple of modi No.Composition Absorb- Concen- fier in Water Gas ed tration, sorbent, cation mole/ m mmole/g /litre t MgCl2 Mg2+ 0.1 0.6 - 0.16 2 Ca(OH)2 Ca2+ 0.03 0.82 - 0.24 3 SrCl2 Sr2+ 0.1 0,9 - 0.26 4 Ba(OH)2 Ba2+ 0.1 1.12 - 0.38 5 Cu(NH3)2C12 Cu2+ 0.1 0.42 - 0.32 6 AgNO3 Ag+ 0.01 0.51 - 0.46 7 CdS04 Cd2+ 0.5 1.5 0.31 8 SbCl in Sb3+ 0.05 0.56 0.28 acetone 9 Pb(N03)2 Pb2+ 0.01 0.09 0.05 0.75 10 Pb(N03)2 Pb2+ 0.1 0.81 0.35 0.35 11 Pb(N03)2 Pb2+ 0.5 1.52 0.5 0,32 12 Bi(N03)3 in Bi3+ 0.1 0.9 0.45 0.27 0.5 mole/ /litre HN03 13 Y(N03)3 Y3+ 0.1 0.38 - 0.22 14 La(N03)3 La3+ 0.1 0.35 - 0,26 15 Mg(N03)2 + Mg2+ + 0.1+0.1 0.36 + - 0.32 Ca(N03)2 Ca2+ 0.42 are subjected to heat treatment at the temperatures of 100, 400, 900 OC.

At the temperature pf 500 C the initial gas is pass ed through the sorbent, while monitoring the concentrat ion of carbon monoxide after the column and the degree of carbon monoxide conversion into carbon dioxide. The con tent of carbon monoxide and carbon dioxide in the gas is determined chromatographically.

The data on the catalytic activity of said sorbent modified with noble metals are presented in Table herein be low.

Table 5 Modifier solution Content Degree of CO CO of modi- conversion during Composi- Metal Concen- fier in heat treatment, % tion absorb- tration, sorbent, ed mole/ mole/g 100 C 400 C 900 C /litre 1. K2[PdCl4] in Pd 35 3.1 98.8 98.8 82.4 0.1 mole/litre HCl 2. K2[Ru(OH)2C1 1 Ru 80 5.3 99.1 990 92.7 in 0.2 mole/ /litre HCl 3. Na3[RhC16] in Rh 25 20 99.1 99.2 92.5 0.11 mole/ /litre RCl 4. K2 [PtCl6] in Pt 6.C 0.5 98.4 98.2 91.8 0.01 mole/ /litre HCl 5. K2 LPtCl6] in Pt 120 9.8 99.4 99.5 91.9 0.01 mole/ /litre HCl 6. K2[PtCl6] in Pt 1200 102 99.9 99.9 92.0 0.01 mole/ /litre HCl The results of tests demonstrate that the sorbent having the herein-proposed composition, modified with noble metals in an amount of 0.0005 - 0.1 mmole/g, may be used with a high efficiency as a heterogeneous catalyst in the oxidation of carbon monoxide on high-temperature gas streams.

Example 19 The activity of work of the granulated sorbent as a catalyst was assessed in a gaseous mixture, having a corn- position (vol. %): 0.28 - CO 0.15 - 02 the balance being argon.

To do that, a modified sample of the sorbent having the formula Ti0.5Zr0.09Sn0.41O2.0.25H2O (Table 2, Example 9), heat-treated at the temperature of 400 OC, is charged into a thermostatted column having an inner diameter of 0.14 mm. The charge height is 40 mm. The sorbent surface is modified as described in Example 17.

After modification the sorbent samples are subjected to heat treatment at the temperatures of 100, 400, 900 OC.

At the temperature of 500 C the initial gas is passed through the sorbent, while monitoring the concentration of carbon monoxide after the column and calculating the degree of conversion of carbon monoxide into carbon dioxide. The content of carbon monoxide and carbon dioxide in the gas is determined chromatographically. The data on the composition of the modified sorbent and on its catalytic activity are presented in Table 6 herein- below.

Example 20 To establish optimal pH range of the gelling liquid, a sol prepared in accordance with Examples .4, 8 of Table 1, is dispersed dropwise into a dilute solution of ammonia with pH 12. The granules are washed with water to neutral reaction and dried in air at 20 OC. The resulting product is a granulated sorbent with the grain size of 2.5 - 3 mm. In a similar manner the sorbent at other pH values of the ammonia solution is prepared; said solution may also be replaced by an alkali. The physico-chemical characteristics of the samples of said sorbents (S, m' depending on the pH of the gelling liquid, are presented in Table 7 hereinbelow.

Table 6 Modifier solution Content Degree of CO#CO2 of modi- conversion during Composition Ion ab- Concen- fier in heat treatment, % sorbed tration, sorbent, mole/ mole/g 100 C 400 C 900 C /litre 1.VO(NO3)2 VO2+ 0.2 0.22 99.9 99.9 93.4 2. CrCl3 Cr3+ 0.2 0.4 97.9 97.9 91.2 3. MnCl2 Mn2+ 0.3 0.91 99.9 99.9 91.6 4. FeCl3 Fe 3+ 0.1 0.25 98.4 98.3 88.8 5. CoCl2 Co2+ 0.2 0.37 98.2 98.4 90 6. NiCl2 Ni2+ 0.2 0.3 98.8 98.9 90.6 7. Ce(NO3)3 Ce3+ 0.1 0.27 98.5 99.1 92.6 8. Cu(NH3)4Cl2 Cu2+ 0.005 0.09 98.6 99.2 89.2 9. Cu(NH2)4Cl2 Cu2+ 0.05 0.62 99.1 99.5 89.6 10.Cu(NH3)4Cl2 Cu2+ 0.25 1.52 99.4 99.7 89.7 Table 7 Exam- Mole ratio of Character- Gelling liquid ple metal chlorides istics No. in sol dOH in ~~~~~~~~~~~~~~~~~ 4 Table Ti Zr Sn pH 110 pH 11.4 pH 12.0 2 2 3 4 5 6 7 8 4 0.4 0.05 0.55 S, m/g - 220 226 #m, kgf/cm Deforma- 50 tion of granules 8 0.4 0.15 0.45 S, m2/g - 230 224 #m, kgf/cm2 Deforma- 50 tion of granules Table 7 (continued) Exam- Gelling liquid ple No.NH4OH NaOH KOH in Table pH 14 concentrated pH 14.0 pH 14.0 1 1 9 10 11 12 4 222 220 205 207 65 80 50 50 8 212 208 207 203 60 75 55 55 From the data presented in Table 7 it is seen that, as concerns the strength of the sorbent material, gelling medium with the pH value a 12 proves to be optimal. At smaller pH the granules are either deformed or destroyed.

Example 21 An aqueous solution containing 0.4 mole/litre of titanium chloride and 0.6 mole/litre of tin chloride with a total concentration of 1 mole/litre (mole ratio Ti:Sn = = 0.4:0.6) is fed to the middle chamber of a three-claam- ber electrolytic cell, separated by corresponding mem- branes from the cathode and anode thereof. The cathode and anode chambers are filled initially with a 0.1 mole/ /litre solution of hydrochloric acid. As the electrodes use is made of materials, resistant to hydrochloric acid and chlorine: graphite for the anode and titanium for the cathode.Electrolysis is carried out at the temperature of 40 C and membrane current density, of 400 A/m2 till the atomic chlorine-to-metal ratio becomes 0,3, The prepared sol is dispersed dropwise through a glass capillary having an inner diameter of 0.25 mm into a gelling liquid, the latter being an aqueous solution of ammonia with pH 12. The gel globules are washed with distilled water to remove the electrolyte and then are heat-treated: one lot at 20 OC, a second lot at 400 OC, and a third lot at 900 OC. The resulting granules of the sorbent have a shape close to the spherical one. At 20 C the size of te sorbent granules is 0.5 - 0.8 mm.

The resulting sorbent has the formula 0.4Sn0.6O2.nH2O where n = 1.8, 0.26, 0.05, respectively, at the heat treatrnent.temperatures of 20, 400, 900 OC, The conditions of the electrochemical stage of pro ducing the sorbent of the formula TixSn1 -x02 0nH20 in accordance with Examples 22-23, realized as in Example 20, are presented in Table 8 hereinbelow.

Table 8 Exam-Aqueous solution of chlorides Electro- Chlor- XRCA data ple . lysis ine-to- (type of No. Total concentra- Molar ratio tempera- metal lattice) tion of metal, of metal ture, C atomic mole/litre chlorides ratio Ti Sn 22 1.0 0.05 0.95 10 1.0 Rutile type 23 1.0 0.90 0.10 80 0.2 Item The XRCA data and the properties of the sorbents prepared in accordance with Examples 21-23 are presented in Table 9 hereinbelow.

T a b l e 9 Exam- Composition of Properties of sorbent, obtained ple sorbent after heat-treatment at No.

20 C n S, #m, XRCA data: type of lattice, main m/g kgf/cm peaks at the angle of 2#.

degree 1 2 3 4 5 6 21 Ti0.Sn0.95O2.nH2O 1c8 230 135 Rutile type 27.0; 34.5; 52.9 22 Ti0.05Sn0.6O2.nH2O 1.8 210 130 Item, 26.4; 33.6; 51.8 23 Ti0.90Sn0.10O2.nH2O 1.8 250 130 Item, 27.1; 34.9; 52.9 Table 9 (continued) Exam- Properties of sorbent, obtained after heat-treatment ple at 125 125 OC 400 OC au, n S, #m, After hydrothermal treatment mole/g m/kg kgf/cm Hydro- XRCA data S, #m, therm m/g kgf/ al sta- bility, /cm hr 1 7 8 9 10 11 12 13 14 21 5.7 0.26 111 320 3000 Rutile 95 130 type,27.0; 34.5; 52.9 22 0.8 0.28 100 460 3000 Item,26.4; 80 130 33.6;51.8 23 12.8 0.26 115 300 3000 Item, 27.1; 90 120 34.9; 52.9 Table 9 (continued) Exam- Properties of sorbent, obtained after heat-treat- ple ment at No.

900 C n S, m/g kgf/cm 1 15 16 17 18 21 0.05 33 470 Rutile type 27.0; 34.5; 52.9 22 0.05 30 500 Item, 26.4; 33.6; 51.8 23 0.05 25 410 Item, 27.1; 34.9; 52.9 According to the data presented in Table 9, all the sorbents of the formula TixSn 1O2.nH2O where x X 0.05 - 0.90, n = 0.05 - 1.8, have a crystalline structure with a lattice of rutile type, feature a developed surface (S = 30 - 250 m2/g) and high strength characteristics (#m = 135 - 500 kgf/cm). The sorbents, obtained after heat-treatment at 400 OC, have a service life longer than 3000 hrs under hydrothermal test conditions.The useful properties of the sorbents, obtained after heat treatment at 125 OC, are confirmed by the fact that they possess sorption capacity for uranium (c'6u = 0.8 - 12.8 mole/g).

Example 24 To carry out modification, a batch of 1 g of the sorbent Ti0.4Sn0.6O2.1.8H2O, prepared as in Example 21 (Table 9) and heat-treated at 20 C, is brought in contact with 100 ml of a solution of a metal salt or of a mixture thereof, and kept under stirring for five days.

On completion of keeping, the solid and liquid phases are separated and the quantity of metal absorbed by the sorbent is calculated from the decrement of its concentrat ion in the solution. The liquid phase is analyzed for the content of lead, cobalt and liquid by the method of complexonometric titration, using complexone III; for the the content of zinc, radiometrically, using Zn isotope; for the content of copper, vanadium, antimony and iron, by the method of acidimetric titration. The sorbent is washed with water and heat treated at 100 OC.

The sorption capacity (&alpha;CH3I) of said sorbent, depending on the composition and concentration of the modifier, is presented in Table 10 hereinbelow.

Table 10 Aqueous solution of modifier Content CH3I in gase of modious phase Composition Cation Concen- fier in under static absorbed tration, sorbent, conditions mole/g mole/g at 110 C mg/g 1. Fe(N03)2 Fe2+ 0.5 1,2 20 2. CoCl2 Co2+ 0.3 0.7 25 3. NiCl2 Ni2+ 0.3 0.7 25 4. Cu(NH3)4012 Cu2+ 1.0 1.4 35 5. ZnCl3 Zn2+ 0.5 0.8 30 6. Pb(N03)2 Pb2+ 0.5 1.5 70 7. Pb(N03)2 Pb2+ 0.01 0.1 10 8. Pb(N03)2 Pb2+ 0.2 0.9 50 9.Fe(NO3)2+CoCl2+ Fe2++Co2++ 1.6 1.5 45 +NiCl2+ +Ni2++ +Cu(NH3)4Cl2+ +Cu2++ +ZnCl2 + + Zn2+ + +Pb(N03)2 + Pb2+ Example 25 The catalytic activity of the sorbent of the formula Ti0.4Sn0.6O2.0.26H2O, modified under the conditions of Example 24, is assessed at the temperature of 500 C in a gaseous mixture, having the following composition (vol. %): 0,28 CO, 0.15 02, the balance being argon.

The catalytic activity characteristics of the modified sorbent are determined as in Example 19.

The data on the catalytic activity (the degree of CO # CO2 conversion) of the sorbent, depending on the composition and concentration of the modifier, are presented in Table 11 hereinbelow.

T a b l e 11 Modifier solution Content of Degree of modifier CO # CO2 Composition Ion ab- Concen- in sorbent, conversion, sorbed tration, mole/g mole/ /litre 1. SbCl3 in Sb3+ 0:2 0.64 99.1 acetone 2. VO(N03)2 V02+ 0.7 0.83 > 99.9 3. Na3PO4 P5+ 1.0 1.5 99.7 4. SbCl3 in Sb3+ 0.05 0.09 98.0 acetone 5.SbCl3 in Sb3+ 0.5 1.5 99.5 acetone 6. SbCl3 in Sb?+ + 1.4 ;1.5 99.8 acetone + +V2+ + +VO(N03)2 + +P5+ +Na3P04 Example 26 An aqueous solution containing 0.04 mole/litre of zirconium chloride and 0.76 mole/litre of tin chloride, with the total concentration of 0.8 mole/litre (the molar ratio Zr:Sn n 0.05:0.95), is fed to the middle chamber of a three-chamber electrolytic cell, separated from the cathode and anode thereof by corresponding ion-exchange membranes. The cathode chamber and the anode chamber are filled with a 0.1 mole/litre solution of hydrochloric acid. The anode is made of graphite and the cathode is made of titanium.The electrolysis is carried out at the membrane current density of 300 A/m2 and the temperature of 38 OC, till the chlorine-to-metal atomic ratio becomes 0.65.

The sol obtained by the electrosynthesis is dispersed dropwise into a gelling liquid, the latter being an aqueous solution of ammonia with pH 12. The gel particles are washed from the electrolytes with distilled water, a first lot is then heat-treated at 20 OC; a second lot, at 400 OC, and a third lot, at 900 00.

The resulting granules of the sorbent have a shape close to the spherical one. At 20 OC the size of the sorbant granules is 0.1 - 0.5 mm.

The sorbent thus prepared has the formula ZrO 05snO9502 .nH0, where n w 1.8, 0.27, 0.05 at the temperatures of 20, 400, 900 OC, respectively.

The conditions of the electrochemical stage of producing the sorbent of the formula ZrySn1 yO2*nH20, according to Examples 27-29, realized as described in Example 26, are presented in Table 12 hereinbelow.

The XRCA data and the properties of the sorbents, obtained in accordance with Examples 26-29, are presented in Table 13 hereinbelow.

T a b 1 e 12 Exam- Aqueous solution of Electro-Chior- XRCA data ple chlorides lysis ine-to- (type of No. tempera-metal lattice) Total concen- Molar ratio ture, atomic tration of of metal C ratio metal, mole/ chlorides /litre Zr Sn 27 0.3 0.02 0.98 10 0.65 Rutile type 28 3.0 0.10 0.90 50 0.58 Item 29 1.5 0.15 0,85 80 0.50 Item Table 13 Exam- Composition of Properties of sorbent, obtained ple sorbent after heat treatment at No.

20 C n S, #m, XRCA data: type m /g kgf/cm of lattice, main peaks at the angle of 28 degree 1 2 3 4 5 6 26 Zr0.05Sn0.95O2.nH2O 1.8 245 130 Rutile type 26.2; 33.1; 51.4 27 Zr0.02Sn0.98O2.nH2O 1.8 250 120 Item, 26.2; 33.1; 51.4 28 Zr0.10Sn0.90O2.nH2O 1.8 248 130 Item, 26.2; 33.1; 51.4 29 Zr0.15Sn0.85O2.nH2O 1.8 250 135 Item, 26.2; 33.1; 51.4 Table 13 (continued) Exam- Properties of sorbent, obtained after heat treatment ple at the temperature of No.

400 C n S, #m, After hydrothermal treatment m/g kgf/cm Hydro- XRCA data S, #m, thermal stabili- m/g kgf/cm ty, hr 1 7 8 9 10 11 12 13 over 26 0.27 78 300 3000 Rutile 43 115 type, 26.2; 33.1; 51.4 over 27 0.25 47 290 3000 Item, 26.2; 43 118 33.1; 51.4 over 28 0.28 90 290 3000 Item, 26.2; 45 120 33.1; 51.4 over 29 0.29 92 300 3000 Item 26.2; 45 120 33.1; 51.4 Table 13 (continued) Exam- Properties of sorbent, obtained after heat treatment ple at No.

900 C n S, #m, XRCA data m/g kgf/cm 1 14 15 16 17 26 0.05 31 210 Rutile type 26.2; 33.1; 51.4 27 0.05 30 205 Item, 26.2; 33.1; 51.4 28 0.05 32 210 Item, 26.2-; 33.1; 51.4 29 0.05 30 220 Item, 26.2; 33.1; 51.4 Example 30 To carry out modification, a batch of 1 g of the sorbent Zr0.05Sn0.95O2.0.27H2O, prepared as described in Example 26 (Table 13) and heat-treated at the temperature of 400 OC, is brought in contact with 100 ml- of a working solution of a salt, and kept under stirring for five days.

In some cases, for increasing the modifier content in the solid phase, the working solution is neutralized by introducing additions of sodium, potassium or ammonium hydro xides. Gn completion of keeping, the solid and liquid phases are separated and the quantity of metal absorbed by the sorbent is calculated from the decrement of the metal concentration in the solution. The liquid phase is analyzed for the content of cobalt, nickel by the method of complexonometric titration with complexone III; for the content of zinc and manganese, radiometrically with the use of 65Zn and 54Mn isotopes; for the content of copper and iron, by the method of acidimetric titration.

The sorbent is washed with water and subjected to heat treatment at 100, 400 and 900 OC.

In Table 14 data are presented on the sorption capacity for iodine ( o4 ) of the modified sorbent, de 2 pending on the composition and concentration oi the modifier.

Example 31 The catalytic activity of the sorbent of the formula Zr0.05Sn0.95O2.0.27H2O, modified under the conditions of Example 30, is assessed at the temperature of 500 C on a gaseous mixture, having the following composition (vol. 5S): 0.28 CO, 0.15 02, the balance being argon. The catalytic activity characteristics of the modified sorbent are determined as in Example 19.

T a b l e 14 Aqueous solution of modifier Content &alpha;I2, mg-equiv./g of modi of modified sorbent Composition Cation Concen- fier in after heat treat absorb- tration, sorbent ed mole/ mole ment at /litre 1000C 4000C 9000C 1. MnCl2 Mn2+ 0.5 0.92 0.95 0.89 0.16 2. Fe(N03)2 Fe2+ 0.5 0.37 0.45 0.43 0.10 3. CoCl2 Co2+ 0.3 0.32 0.76 0.72 0.12 4. NiCl2 Ni2+ 0.3 0.13 0.48 0.45 0.09 5. ZnCl2 Zn2+ 0.5 0.48 0.52 0.48 0.09 6. Cu(NH3)4Cl2 Cu2+ 0.5 1.50 1.41 1.32 0.26 7. Cu(NH3)4Cl2 Cu2+ 0.01 0.1 0.40 0.38 0.08 8. Cu(NH3)4Cl2 Cu 0.1 0.48 1.06 0.96 0.16 9. Mn(N03)2 + Mn2+ + 0.4+0.4 #0.75 0.87 0.82 0.18 Co(NO3)2 +Co2+ T a b l e 15 Exam- Aqueous solution of modifier Content Degree of ple of modi- CO # CO2 con No.Composition Metal Concen- fier in version, % absorb- tration, sorbent, ed mole/ mole/g /litre 17 K2[PdCl4j in Pd 45 4o2 990 0.1 mole/ /litre HCl 18 K2[PtCl4J in Pt 7.5 0.5 99.3 19 Ditto Pt 145,0 12.0 99.6 20 Ditto Pt 1200 100.0 99.9 In Table 15 data are presented on the catalytic acti vity of the sorbent (degree of CO # CO2 conversion), de pending on the composition and content of the modifier.

Industrial Applicability The herein-proposed granulated inorganic sorbent, due to its high sorption and catalytic activity, high strength of the granules, developed porous structure which is stable in time, the presence of different modifiers on the surface thereof, whenever necessary, will provide an increase in the efficiency of different hightemperature technological processes. The sorbent of the invention possesses a high hydrothermal stability.This will make it applicable for the purification of the non -cooled aqueous heat-transfer agent oi atomic power plants from the products of corrosion and radionuclides, whereby the useful time of the reactor will be increased, thermal losses will be reduced, deposits in the loop will be diminished, the radiation situation in the serviced premises will be improved; as a result, the consumption of doses will be cut down, i.e. the economical efficiency and reliability of the atomic power plants will be increased.

The sorbents proposed herein may be used with a high efficiency for the purification of the gaseous heat transfer agent, gaseous discharges of the nuclear reactor from different radionuclides, including iodine and iodine derivatives, and also in catalytic high-temperature processes for the utilization of harmful gaseous discharges, which gives an appreciable economic effect.

Said properties will make the sorbent applicable in the atomic power engineering, in the chemical industry, in heterogeneous catalysis.

Claims (19)

1. A granulated inorganic sorbent on the basis of oxides of metals belonging to group IV of the Periodic System, c h a r a c t e r i z e d in that it has the following formula TixZrySn-1-x-yO2.nH2O where O t x + y i 1, x = 0 - G.95, y = O - 0.15, n = 0.05 - 1.8, a specific surface of 30 to 250 m2/g and is a solid solution with a rutile type structure, and with diffractogram, as measured using Cu-K &alpha;-radiation, cha- racterized by principal peaks at the angle 2 # equal to 26-8#0.7, 34.5#1.5, 52.8#1.5 degrees.

2. A granulated inorganic sorbent according to Claim 1, c h a r a c t e r i z e d in that it has the following formula TixZrySn1-x-yO2.nH2O where x = 0.05 - 0.40, y = 0.02 - C.15, n = 0.05 - 1.8, and has a structure corresponding to a diffractogram, characterized by principal peaks at the angle 2 # equal to 26.8+0.4, 34.0+0.9, 52.2+0.8 degrees.

3. A granulated inorganic sorbent according to Claim 1, c h a r a c t e r i z e d in that it has the following formula TixZrySn1-x-yO2.nH2O where x 0.40 - 0.95, y 1 0.02 - 0.15, n - 0.05 - 1.8, possessing a structure with an X-ray diffractogram cha racterized by principal peaks at the angle 2 # equal to 26.8+0.4, 35.2+0.9, 53.5+0.8 degrees.

4. A granulated inorganic sorbent according to Claim 1, c h a r a c t e r i z e d in that it has the following formula TixSn1-xO2.nH2O where w 2 0.05 - 0.90, n = 0.05 - 1.8, possessing a structure with a diffractogram characterized by principal peaks at the angle 2 & equal to 26.8+0.7, 34.5+1.5, 52.8+1.5 degrees.

5. A granulated inorganic sorbent according to Claim 1, c h a r a c t e r i z e d in that it has the following formula: ySn1-yO2.nH2O where y X 0.02 - 0.15, n = 0.05 - 1.8, possessing a structure with an X-ray diffractogram characterized by principal peaks at the angle 20 equal to 26.2+0.05, 33.1+0.05, 51.4+0.05 degrees.

6. A granulated inorganic sorbent according to Claim 1, c h a r a c t e r i z e d in that its surface may be modified by at least one element selected from one of groups I, II, III, V, VI, VII, VIII of the Periodic System, the amount of the said element being within 0.0005 to 1 ,5 mole/g of the said sorbent.

7. A granulated inorganic sorbent according to Claim 1, c h a r a c t e r i z e d in that its granules have a spherical shape and a size of 0.001 to 3 mm, limit of fracture being at least 50 kgf/cm2.

8. A method of producing a granulated inorganic sorbent according to Claim 1 on the basis of oxides of metals belonging to group IV of the Periodic System, c h ar a c t e r i z e d in that an aqueous solution containing tin chloride and at least one chloride of a metal selected from the group of titanium and zirconium at a molar ratio Ti:Zr:Sn . (0 - 0.95):(0 - 0.15)::(0.03 - 1.0) is subjected to electrolysis till the atomic ratio of chlorine to the metal becomes equal to 0,2 - 1.0, ensuring the formation of a mixed sol of the hydrated oxides of metals, followed by dropwise dispersing of said sol in a gelating liquid with pH a 12, separating of the formed gel particles, which are then washed and subjected to heat treatment at a temperature within 20 to 900 C yielding granules of the desired product having the following formula:: TixZrySn1-x-yO2.nH2O where O < x + y ( 1, x = 0 - 0.95, y " O - 0.15, n = = 0.05 - 1o8, having a specific surface of 30 - 250 m2/g and representing a solid solution with a rutile type structure, and with X-ray diffractogram, as measured using CU-K&alpha;-radiation, characterized by principal peaks at the angle 2 # # equal to 26.8+0.7, 34.5+1.5; 52.8+1.5 degrees.

9. A method according to Claim 8, c h a r a c t e ri z e d in that the aqueous solution subjected to electrolysis contains chlorides of titanium, zirconium and tin at the molar ratio Ti:Zr:Sn = (0.05-0.40):(0.02 0.15):(0.43-0.95) till the atomic ratio of chlorine to metal becomes 0,2 - 1.0.

10. A method according to Claim 8, c h a r a c t e ri z e d in that the aqueous solution subjected to electrolysis contains chlorides of titanium, zirconium and tin at the molar ratio Ti:Zr:Sn X (0.40-0.95):(0.02 0.15):(0.03-0.45) till the atomic ratio of chlorine to metal becomes 0.2 - 1 .0.

11. A method according to Claim 8, c h a r a c t e ri z e d in that the aqueous solution subjected to electrolysis contains chlorides of titanium and tin at the molar ratio Ti:Sn = (0.05-0.90):1 till the atomic ratio of chlorine to metal becomes 0.2 - 1.0.

12. A method according to Claim 8, c h a r a c t e ri z e d in that the aqueous solution subjected to electrolysis contains chlorides of titanium and tin at the molar ratio Ti:Sn # (0.02-0.15):(0.85-0.98) till the atomic ratio of chlorine to metal becomes 0,50 - 1.0.

13. A method according to Claim 8, c h a r a c t e ri z e d in that an aqueous solution of ammonia or an alkali is used as the gelling liquid.

14. A method according to Claim 8, c h a r a c t e ri z e d in that said sorbent, after heat treatment, is treated, in order to modify its surface, with a 6x10-6 1.5 mole/litre solution of at least one salt of an element selected from groups I, TI, III, V, VI, VII, VIII ot the Periodic System, or a hydroxide of at least one metal selected from group I or II of the Periodic System and subjected to heat treatment at a temperature within 100 to 900 ,:

15. A method according to Claim 8, c h. a r a c t e ri z e d in that the total concentration of chlorides of said metals in the aqueous solution subjected to electr- lysis is within 0.3 to 3 mole/litre.

16, A method according to Clam 8, c h a r a c t e ri z e d in that the electrolysis is conducted at a temperature within 10 to 80 OC.

17. A granulated inorganic sorbent according to Claim 1 for purification of aqueous, organic or gaseous heat transfer medium of a nuclear reactor from radionuclides and corrosion products at elevated temperatures and pressures.

18. A granulated inorganic sorbent according to Claim 1 or 4 for purification of steam-gas emissions from a nuclear reactor from radionlelides of iodine, its organic compounds and radioactive aerosols.

19. A granulated inorganic sorbent according to Claim 1 or 4 for neutralization of exhaust gases of internal combustion engines.