RU2504594C1 - Method of extracting molybdenum and cerium from spent iron oxide catalysts for dehydrogenating olefin and alkyl aromatic hydrocarbons - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: extraction of molybdenum and cerium is carried out in two steps, where molybdenum is extracted at the first step and a cerium compound is extracted at the second step. The first step involves crushing a catalyst, adding a solution of a leaching agent in weight ratio to the spent catalyst of (0.5-10):1, in concentration of not less than 0.1 mol/l, stirring the suspension for 4-10 hours at temperature of 90-95°C, filtering the mixture to separate the residue and washing the residue with water. A mixture is then prepared from the filtrate and water from washing the residue containing molybdenum. The mixture is the evaporated to obtain an end product. The second step of extracting the cerium compound is then carried out, where the residue of the crushed catalyst is completely dissolved in hydrochloric acid, water is added and then evaporated to the initial volume of the solution, the undissolved portion is separated by filtering, the remaining solution is neutralised to pH 3.5-4.5 with control thereof, the solution is heated to 90-100°C while stirring, followed by successively adding a calcium salt solution in ratio of calcium to the catalyst from 1:100 to 5:100 and a saturated oxalic acid solution in ratio to the catalyst from 5:1 to 10:1, stirring at temperature of 70-100°C for 2-6 hours, holding the solution to precipitate the cerium compound for 4-24 hours at room temperature, separating the precipitate from the mother solution by filtering, washing and drying to constant mass. The invention also discloses a method of extracting molybdenum only from said catalyst and a method of extracting cerium only from said catalyst.EFFECT: extracting molybdenum and cerium with high percentage output and purity by preventing the effect of the extracted components on each other.19 cl, 2 tbl, 18 ex

Description

The present invention relates to the chemical industry, and in particular to a method for the integrated processing of spent iron oxide catalysts, specifically olefin and alkyl aromatic hydrocarbon dehydrogenation catalysts, with the recovery of valuable components such as cerium and molybdenum. The obtained compounds of these elements can be used either in the production of iron oxide catalysts as starting materials, or, as independent reagents, in other industries.

Today, most of the processes of chemical technology are catalytic; the key role in ensuring the effectiveness of these processes is played by catalysts. The role of catalytic systems in chemical technology can hardly be overestimated, but their use is inextricably linked to the problem of spent catalysts, the technological parameters of which have decreased below the permissible level and which can no longer be used for their intended purpose. Spent catalysts are multi-ton industrial waste, often containing substances that have a strong toxic effect on the environment. Such substances include oxides of many transition and rare earth elements. Most of the spent catalysts are subjected to simple disposal, which is dangerous and disadvantageous, both from an environmental and from an economic point of view. Spent catalysts are valuable secondary raw materials, which leads to the inefficiency of their simple disposal; In addition, for the neutralization (reduction of toxicity of waste) of many catalysts, special technologies are needed (encapsulation, cementation), as well as specially equipped landfills, the equipment costs of which are very high. All this indicates that the recycling of spent catalysts, or recycling, is an urgent task.

Modern catalysts for the dehydrogenation of olefin and alkylaromatic hydrocarbons by chemical and phase composition can be attributed to the most complex in the processes of organic synthesis. Their main component is α-Fe ₂ O ₃ , the initial content of which is 55-85% of the mass. Another mandatory component is any compound of potassium (K ₂ O, K ₂ CO ₃ ), the concentration of which is 2-20% of the mass. in terms of K ₂ O. The promoters also use oxides of transition and rare earth elements - molybdenum up to 2.5%, tungsten, vanadium, manganese, cerium (5-60% by weight in the form of carbonates, oxides, nitrates and hydroxides) and nickel. The most expensive of these promoters are molybdenum and cerium, since their compounds account for about 75% of the cost of the catalyst: about 20% and 55% for molybdenum and cerium, respectively, so the extraction of these components is the first priority.

To extract molybdenum from spent catalysts, one-step leaching methods are widely used using leaching agents - solutions of ammonia and ammonium salts with the simultaneous extraction of some other components. In one of the first patented processes, when a solution of hydrotreating, previously calcined at 650 ° C, was leached with an ammonium carbonate solution for 30 minutes at a temperature of 125-175 ° C, it was possible to recover about 90-99% molybdenum, among other metals [US 3567433 A, 1971.03. 02]. The specified method is designed only for a specific catalyst with a different composition (oxides of aluminum, cobalt and molybdenum), and is not applicable to the catalysts in accordance with the invention. In addition, the extraction temperature is 125-175 ° C, which determines the high energy intensity of the process and is economically disadvantageous.

In addition, the nature of the process was strongly influenced by the extraction regimes: the coke burning temperature and the treatment time with an ammonia solution. Thus, an increase in the temperature of regeneration above 600 ° C negatively affected the extraction of nickel, and the treatment time, more or less 5-10 minutes, reduced the release of cobalt.

Another disadvantage is the one-time method for extracting various catalyst components using one leaching agent and the same technology for their extraction. This affects the percentage of their extraction: one component with a given extraction mode and identical leaching agents has a high percentage of yield, and the other, due to their different nature, has a lower yield, resulting in the loss of some elements. In addition, with a one-stage, simultaneous method of extracting several components, the problem arises of their separation, the process becomes more complicated due to the need for liquid extraction, for example, quaternary ammonium salts.

Known two-stage extraction of expensive elements from spent catalysts, which partially eliminates this disadvantage. It includes 2 stages of processing the spent catalyst with liquor solutions, and in one of the stages an alkaline solution (alkali or ammonia solution) is used, and on the other, acidic (inorganic or organic acid). Another embodiment of this two-step method is the sequential use of alkali solutions and ammonia solution. In one study (Sun DD Recovery and marine clay stabilization of heavy metals present in spent hydrotreating catalysts. / DD Sun, L. Chang, JH Tay, JD Navratil), using this method, the authors were able to extract 83% Mo and 44% Ni from spent NiMo / Al ₂ O ₃ catalysts, which is a fairly low rate of molybdenum recovery. In addition, the composition of the catalyst is different compared with the invention, and the method is not suitable for use.

Known and widely used methods for the extraction of molybdenum is the processing of objects containing molybdenum in oxide form, alkaline solutions, such as carbonates or hydroxides of alkali metals [Busev A.I. Analytical chemistry of molybdenum. / A.I. Busev. - M.: Academy of Sciences of the USSR, 1962. - 299 p .; Sittig M. Extraction of metals and inorganic substances from waste. / M. Sittig; trans. from English - M .: Metallurgy, 1985. - 408 p.]. Since the presence of even a small amount of sodium ions causes poisoning of the catalysts, the most appropriate is the use of carbonate or potassium hydroxide. The interaction rate of molybdenum oxide with a solution of potassium carbonate is higher than with a solution of potassium hydroxide, which is explained by loosening of the surface of the particles with carbon dioxide released during the reaction with carbonate, enhancing the hydrolysis of potassium carbonate in the surface layer of particles of the crushed catalyst [Stepanov EG Development of methods for the qualified use of spent iron oxide catalysts for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons / E.G. Stepanov, G.R. Kotelnikov, A.V. Kuzhin et al. // Chemistry and Chemical Technology. - 2003. - T.46. - issue 9. - S.68-71; Transition S.P. Kinetics of leaching of molybdenum trioxide from spent catalyst with sodium carbonate solutions. / S.P. Transition, Yu.A. Liner, E.Yu. Nevskaya // Chemical technology. - 2006. - No. 11. - S.23-26].

A known method for the separation of cerium [2000122097 A, IPC 7 C01F 17/00, C01G 56/00, G21C 19/46 with the date of publication of the application: 08/20/2002], in which the selection is carried out from solutions of irradiated materials, including extraction of cerium (IV) or Berkelium (IV) with D2EGFK solution and reextraction with nitric acid solutions, simple saturated alcohols are introduced into the organic phase before cerium or Berkelium is reextracted, to a concentration that ensures complete recovery of cerium or Berkelium, then it is reextracted with nitric acid solution (~ 2 mol / L), not containing a reducing agent. The disadvantages of this method are the use of organic solvents that are toxic, and the inability to use it due to the different nature of the recoverable elements from the mixture of ions in the catalyst in accordance with the invention.

A known method for the separation of cerium [RU 2373299 C1, a Method for the extraction and separation of cerium and yttrium ions, IPC C22B 59/00, B03D 1/00, published: 20.11.2009], which relates to the production of pure rare earth metals (REM) or their oxides from poor or man-made materials using the ion flotation method. A method for extracting cerium and yttrium ions from a solution involves ion flotation using a surfactant as a collector. Sodium dodecyl sulfate at a concentration corresponding to the stoichiometric reaction is used as a collector: Me + 3 + 3DS- = Me [DS-] 3, where Me + 3 is the cerium or yttrium cation, DS- is the dodecyl sulfate ion. Moreover, for selective extraction of yttrium and separation of yttrium and cerium ions, ion flotation is carried out at pH = 5. The technical result is to increase the percentage of extraction and separation of cerium and yttrium ions.

Known methods for producing cerium in the form of oxalate, for example, deposition of cerium from a solution in the form of oxalate is described [Mikhaylichenko A.I., Mikhlin E.E., Patrikeyev Yu.V. Rare earth metals. M .: Metallurgy, 1987]; the specified source describes the preparation of cerium oxalate from a solution containing a mixture of rare earth elements. However, the described method does not apply to the extraction of cerium from the catalysts. Known methods for the extraction of cerium are not applicable to the invention relating to the processing of the catalyst as a complex multicomponent system.

Thus, the known methods for the extraction of molybdenum and cerium belong to the starting systems and catalysts of a different nature, therefore, they are not applicable for the complex processing of spent iron oxide dehydrogenation catalysts for alkyl aromatic and olefin hydrocarbons, which are a system of a mixture of metal oxides of various nature. Previously, methods for the complex processing of spent iron oxide catalysts, specifically catalysts for the dehydrogenation of alkyl aromatic and olefin hydrocarbons, with the recovery of valuable components such as cerium and molybdenum, were not known and have not been described.

The objective of the invention is to extract molybdenum and cerium as the most expensive components from iron oxide catalysts for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons with a high percentage of their yield and purity by eliminating the mutual influence of the extracted components on each other.

The problem is solved, and the technical result is achieved by the claimed method for the extraction of molybdenum and cerium from spent iron oxide catalysts for the dehydrogenation of olefin and alkylaromatic hydrocarbons, in which the extraction of molybdenum and cerium is carried out in two stages, at the first stage, the molybdenum compound is extracted, and then the second stage of processing the catalyst residues is carried out with the extraction of cerium compounds.

In this case, at the first stage

- spend grinding the spent catalyst;

- a solution of the leaching agent is added to the crushed catalyst in a mass ratio to the spent catalyst (0.5-10): 1, a solution of alkali or alkali metal carbonate, preferably cadmium, at a concentration of not less than 0.1 mol / l is used as a leaching agent;

- spend mixing the suspension for 4-10 hours with the exception of evaporation of water, at a temperature of 90-95 ° C;

- after mixing is carried out, the mixture is filtered to precipitate;

- the precipitate is washed with water to wash the residual molybdenum;

- prepare a mixture of filtrate and washings of sediment containing molybdenum - a solution of alkali metal molybdate;

- the resulting mixture is evaporated 2 times at a temperature of 70 ° C - 100 ° C to obtain a marketable product with a molybdenum content in solution of 5-6 g / l, ready for the preparation of the catalyst.

The resulting solution can be used as a commercial product in the preparation of the catalyst or for the isolation of pure molybdate by standard methods.

Next, carry out the second stage of extraction - extraction of cerium in the form of oxalate, for which

- spend the complete dissolution of the remainder of the crushed catalyst in concentrated hydrochloric acid by stirring at a temperature of 30-95 ° C for 30-90 minutes; temperature and time are determined by complete dissolution;

- in the resulting solution add water from an equal to two times the volume and the mixture is heated to 95-100 ° C, evaporating it to the original volume;

- after evaporation, the insoluble part is separated by filtration, separating the insoluble impurities;

- the solution remaining after filtration is neutralized until a pH of 3.5-4.5 is obtained, while controlling the pH; to neutralize using a 5-25% solution of ammonia;

- after such neutralization, the solution is heated to 90-100 ° C with stirring;

- after reaching a predetermined temperature, a solution of calcium salt in a mass ratio of calcium: catalyst from 1: 100 to 5: 100 and a saturated solution of oxalic acid in a mass ratio to catalyst from 5: 1 to 10: 1 are successively added to the solution;

- after adding all the components are mixing at a temperature of 70-100 ° C for 2-6 hours;

- spend the exposure of the solution for the deposition of cerium oxalate for 4-24 hours without heating, at room temperature;

- after receiving the precipitate, it is separated from the mother liquor by filtration, draining the solution from the surface of the precipitate onto the filter with a pore size of the filter material of not more than 2 microns;

- the filter cake is washed with a 1-2% solution of oxalic acid, preferably while stirring the filter cake to better wash off the iron compound, to obtain ten-water cerium oxalate;

- a filtration solution of an iron compound, in particular iron chloride, can be used for further processing;

- ten-cerium oxalate of cerium is sent for drying in an oven at a temperature of 90 ° C to constant weight to obtain a cerium-containing finished product - cerium oxalate.

The problem is solved and the technical result is achieved by the claimed method of extracting molybdenum from spent iron oxide catalysts for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons, which consists in the following:

- spend grinding the spent catalyst;

- a solution of the leaching agent is added to the crushed catalyst in a mass ratio to the spent catalyst (0.5-10): 1, a solution of alkali or alkali metal carbonate at a concentration of not less than 0.1 mol / l is used as a leaching agent;

- spend mixing the suspension for 4-10 hours with the exception of evaporation of water, at a temperature of 90-95 ° C;

- after mixing is carried out, the mixture is filtered to precipitate;

- the precipitate is washed with water to wash the residual molybdenum;

- prepare a mixture of filtrate and washings of sediment containing molybdenum - a solution of alkali metal molybdate;

- the resulting mixture is evaporated at a temperature of 70 ° C-100 ° C 2 times to obtain a marketable product with a molybdenum content in solution of 5-6 g / l, ready for the preparation of the catalyst.

The resulting solution can be used as a commercial product in the preparation of the catalyst or for the isolation of pure molybdate by standard methods.

After extraction of the molybdenum compound, it is possible to treat the catalyst residues remaining after washing the precipitate with water for the second extraction step.

The problem is also solved, and the technical result is achieved by the claimed method of extracting cerium from spent iron oxide catalysts for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons, which consists in the following:

- spend the complete dissolution of the crushed catalyst in concentrated hydrochloric acid by stirring at a temperature of 30-95 ° C for 30-90 minutes; temperature and time are determined by complete dissolution;

- in the resulting solution add water from an equal to two times the volume and the mixture is heated to 95-100 ° C, evaporating it to the original volume;

- after evaporation, the insoluble part is separated by filtration, separating the insoluble impurities;

- the solution remaining after filtration is neutralized until a solution pH of 3.5-4.5 is obtained, while controlling the pH, a 5-25% ammonia solution is used to neutralize it;

- after such neutralization, the solution is heated to 90-100 ° C with stirring;

- after reaching a predetermined temperature, a solution of calcium salt in a mass ratio of calcium: catalyst from 1: 100 to 5: 100 and a saturated solution of oxalic acid in a mass ratio of oxalic acid to catalyst from 5: 1 to 10: 1 are successively added to the solution;

- after adding all the components are mixing at a temperature of 70-100 ° C for 2-6 hours;

- spend the exposure of the solution for the deposition of cerium oxalate for 4-24 hours at room temperature;

- after receiving the precipitate, it is separated from the mother liquor by filtration, draining the solution from the surface of the precipitate onto the filter with a pore size of the filter material of not more than 2 microns;

- the filter cake is washed with a 1-2% solution of oxalic acid, preferably while stirring the filter cake to better wash off the iron compound, to obtain cerium ten-oxalate.

A filtration solution of an iron compound, for example iron chloride, can be used for further processing.

Ten-cerium oxalate is sent for drying in an oven at a temperature of 90 ° C to constant weight to obtain a cerium-containing finished product - cerium oxalate.

The object is very complex and the number of parameters that need to be varied is more than ten. This means that in order to achieve the required cleanliness and yield, tens of thousands of experiments must be done. This was the difficulty. We managed to optimize the extraction and find the conditions that allow us to obtain products (molybdenum and cerium) that can be used both as independent reagents and in the production of the catalyst. Previously, methods for the complex processing of spent iron oxide catalysts, specifically catalysts for the dehydrogenation of alkyl aromatic and olefin hydrocarbons, with the recovery of valuable components such as cerium and molybdenum, were not known and have not been described.

When extracting cerium without a molybdenum extraction stage, the latter remains in a solution of a complex composition and it is very difficult to extract, and it is forbidden to discharge such molybdenum-containing compounds into wastewater.

In the absence of molybdenum in the spent iron oxide catalyst for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons, for example KDO, Russia, TU 2173-134-5766801-2005, the claimed method of extracting cerium from the spent iron oxide catalysts for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons independently can be used.

The method used the following products and reagents:

- Spent iron oxide catalysts for the dehydrogenation of alkyl aromatic and olefin hydrocarbons (isoamylenes in isoprene and ethylbenzene in styrene):

- S6-34, Basf, Germany

- KDOM-08, Russia, TU 2173-134-5766801-2005

- KDO, Russia, TU 2173-134-5766801-2005

- KDES, Russia, TU 2173-0134-05766801-2005

- Leaching agent:

- Potassium carbonate, technical grade 1, GOST 10690-73

- Caustic potassium, grade h, GOST 24363-80

- Soda ash, class A (second grade), GOST 5100-85

- Caustic soda, technical grade tr, GOST 2263-79

- Hydrochloric acid, class A, GOST 3118-77

- Ammonia water, GOST 3760-79

- Anhydrous calcium chloride, GOST 450-77

- Oxalic acid, two-water, GOST 22180-76

- Chemically desalinated water of the third stage of purification, GOST 6709-726709-72.

A method of processing an iron oxide catalyst for the dehydrogenation of alkyl aromatic and olefin hydrocarbons with the extraction of molybdenum and cerium is carried out as follows.

The spent catalysts for the dehydrogenation of alkyl aromatic and olefinic hydrocarbons are subject to processing in accordance with the proposed method: dehydrogenation of isoamylenes to isoprene of a composition close to catalysts of grades S6-34 (BASF, Germany), KDOM-08 (RF), KDO (RF), and ethylbenzene to styrene KDES (RF), which is a polydisperse mixture of whole, broken and sintered granules, as well as a black powdery mass with the following chemical composition obtained by atomic absorption spectroscopy:

Element Oxide The range of content,% of the mass. Fe ₂ O ₃ 55-85 Moo ₃ 0-5 CeO ₂ 7-12 K ₂ O 2-20 CaO 0-6 MgO 0-6

Used spent catalyst is pre-crushed on a disintegrator. It is desirable that the spent catalyst be milled to a fractional particle composition of not more than 0.2 mm, which leads to the most complete extraction of the components — molybdenum and cerium, and to the acceleration of the extraction process — the smaller the particle size, the larger their surface, and the faster the reaction . As a leaching agent, a solution of alkali or alkali metal carbonate, preferably potassium, is taken in an amount in which its mass ratio to the spent catalyst is from 0.5: 1 to 10: 1. An alkali metal or alkali carbonate solution is prepared in a container at a concentration of 0.1 to 1.1 mol / L when the solution is heated to 90-95 ° C, with the exception of water evaporation, for which a container is taken with a reflux condenser. A leaching agent concentration of at least 0.1 mol / L is necessary to achieve a technical result - a high degree of molybdenum recovery. A higher concentration of the leaching agent also leads to the achievement of a technical result, however, it is impractical from the point of view of uneconomical expenditure of the leaching agent. The crushed catalyst is added to the solution to form a suspension, the suspension is stirred for 4-10 hours at the indicated temperature with a stirring speed of 900 rpm, preferably with the exception of the evaporation of water. After mixing is completed, the mixture is filtered, mainly vacuum, with precipitation. In this case, the end of mixing is established empirically when monitoring the percentage of extraction of molybdenum of at least 90%. After that, the precipitate is washed with chemically desalted or distilled water; prepare a mixture of filtrate and washings of the precipitate containing alkali metal molybdate. The resulting mixture is evaporated at a temperature of 70-100 ° C to reduce the initial volume of the mixture by half, until the molybdenum content in the solution is 5-6 g / l. The resulting solution before evaporation or after cooling the evaporated mixture is a product that can be used to obtain an iron oxide catalyst in the future.

The determination of the molybdenum content in the catalyst and in the extract is carried out by the photocolorimetric method [Yu. Yu. Lurie. Analytical chemistry of industrial wastewater. M .: Chemistry. - 1984. R. Bock. Decomposition methods in analytical chemistry. M .: Chemistry. - 1984. - S.223]. The method is based on the reduction of Mo ⁺⁶ ions formed in the solution after decomposition of the sample to Mo ^{+5 with} thiocarbamide in the presence of a copper sulfate catalyst and subsequent photocolorimetric determination at (434 ± 10) nm of colored complexes formed during the interaction of Mo ⁺⁵ with rhodanide ions. The yield (degree of extraction) of molybdenum in percent is calculated as the ratio of the mass of molybdenum (or molybdenum oxide) in the sample of the catalyst to the mass of molybdenum (or molybdenum oxide) in the solution after extraction.

After extraction of the molybdenum compound, it is possible to process the catalyst residues remaining after washing the precipitate with water, for which the catalyst residues are dried in a drying oven to constant weight, at a temperature of 105-120 ° C for 5-6 hours; the residual catalyst can not be dried, and measure the humidity and calculate the amount of other components based on the moisture content for the second stage of extraction. Next, the second stage of extraction is carried out - extraction of the cerium compound (cerium oxalate), for which concentrated hydrochloric acid is poured into a chemically resistant container and the prepared residue of the crushed catalyst is poured, it is dissolved in concentrated hydrochloric acid by stirring using a magnetic stirrer at a speed of 300-400 b / min at a temperature of 30-95 ° C for 30-90 minutes. An equal to twice the volume of distilled water is added to the resulting solution, and the mixture is heated to 95-100 ° C, evaporating it to the original volume to remove excess acid, since the excess volume of the solution negatively affects the yield of oxalate. After evaporation, the insoluble part is separated by filtering the solution on a filter, for example, using white tape paper, separating insoluble impurities. After filtration, the remaining solution is placed in a heat-resistant container with a stirrer, for example, magnetic, and it is stirred at a speed of 150-200 rpm. With stirring, a 5-25% ammonia solution is added to the solution until a pH of 3.5-4.5 is obtained, while controlling the pH to bind an excess of acid, which makes it difficult to precipitate cerium oxalate in the future; excess volume of the solution negatively affects the output; this gives a thick gel-like brown solution. After such neutralization, the solution is heated to 90-100 ° C with stirring at a stirrer speed of 250-300 rpm until the specified temperature is reached. Then, a solution of calcium salt in a weight ratio of calcium: catalyst of 1: 100 to 5: 100 is sequentially added to the solution (to the mass of the catalyst that was taken to extract cerium and went into dissolution taking into account the moisture content), and a saturated 20% solution of oxalic acid in a mass ratio to the catalyst from 5: 1 to 10: 1. Calcium salt is needed for better crystallization of the precipitate. Otherwise, the precipitate may not precipitate, or not completely precipitate, or be too dispersed, which impedes or complicates the filtering. After adding all the components, stirring is carried out at a temperature of 70-98 ° C for 3 hours. Spend the solution for precipitation for 4-24 hours without heating, at room temperature. After receiving the precipitate, it is separated from the mother liquor by filtration - the solution is drained from the surface of the precipitate onto the filter with a pore size of the filter material of not more than 2 μm. The filter cake is washed, preferably with a 1-2% solution of oxalic acid, and preferably with stirring of the filter cake to better wash off the iron chloride. After washing the precipitate, it contains ten-cerium oxalate of cerium, which is sent for drying in an oven at a temperature of 90 ° C to constant weight to obtain a cerium-containing finished product - cerium oxalate. The remaining filtration solution of iron chloride can be used for further processing.

This order of extraction of elements allows to minimize the content of molybdenum in the catalyst, which interferes with the extraction of other elements. It allows you to increase the yield of recoverable cerium compounds. By extraction with a potassium carbonate solution or other leaching agent, only molybdenum can be extracted from the solid catalyst, the remaining elements, including cerium, are not recovered. If you dissolve the catalyst and immediately begin to extract cerium, then the precipitate may be contaminated with molybdenum, in addition, molybdenum will remain in the filtrate, and it will also need to be removed.

The inventive methods allow to extract from the spent catalysts for the dehydrogenation of alkyl aromatic and olefin hydrocarbons the most expensive components in high yield and to obtain products of high purity.

The yield (degree of extraction) of the product is considered as the ratio of the molybdenum / cerium content in the catalyst (in terms of their compound) to the actually extracted molybdenum or cerium. The optimal yield is achieved by varying and combining technological methods and experimental conditions.

The purity of the obtained compounds is calculated from the results of their analysis by X-ray fluorescence or atomic absorption methods [GOST 23862.0-79. Rare earth metals and their oxides. General requirements for analysis methods. M .: IPK Publishing house of standards. 2003; International standard ISO 12677: 2003 “Chemical analysis of refractory products by X-ray fluorescence (XRF) - Fused cast bead method"; X-ray fluorescence chemical analysis of refractories (XRF); GOST 12364-84. Steel alloyed and high alloyed. Methods for the determination of cerium; GOST 23862.2-79. Rare earth metals and their oxides. Direct spectral method for the determination of impurities of rare earth oxides].

The invention is illustrated by examples of specific performance.

Table 1 shows examples of the extraction of molybdenum from various spent catalysts for the dehydrogenation of olefin and alkylaromatic hydrocarbons and the results of the extraction of molybdenum under various conditions; Table 2 shows examples of cerium recovery with their results. The numbers of the examples in Table 2 correspond to the numbers of the examples in Table 1. So, example 2.1 extraction of cerium was carried out after extraction of molybdenum according to example 1.1, etc.)

Examples of stage 1. Molybdenum recovery (Table 1).

Example 1.1.

In a conical flat-bottomed flask, pour 200 ml of distilled water into a cylinder and add 5.02 g of potassium carbonate, weighed on an analytical balance with an accuracy of 0.01 g (the concentration of potassium carbonate is 0.363 mol / l). Dissolve the sample when heated on an electric stove to a temperature of 95 ± 3 ° C. Then, 100 g of catalyst crushed in a disintegrator to a particle size not exceeding 0.20 mm are introduced into the flask, Basf, Germany, brand S6-34, containing 2.56 g of molybdenum oxide; while the mass ratio of the solution of potassium carbonate to the catalyst is approximately 2: 1. In the resulting suspension is placed a mechanical stirrer, providing continuous mixing of the reaction mass at a constant speed (900 rpm). To prevent evaporation of water from the solution, a reflux condenser is used. The time of the process is fixed from the moment the catalyst is weighed.

The interaction of molybdenum (VI) oxide with potassium carbonate in solution occurs by the reaction:

MoO ₃ + K ₂ CO ₃ → K ₂ MoO ₄ + CO ₂

Stirring is continued for 6 hours at a temperature of 95 ° C, after which the mixture is vacuum filtered, the precipitate is washed with distilled water (100-150 ml). Wash water and the filtrate are combined, evaporated at t = 95 ° C in 2 times by volume, cooled and fixed volume. A sample of 1.00 ml is taken and the molybdenum content in the solution is determined. The mass of molybdenum in terms of molybdenum oxide in the solution was 2.49 g. The resulting solution is a ready-to-use product. The output (degree of extraction) of molybdenum, calculated as the ratio of the mass of molybdenum in the initial sample of the catalyst to the mass of molybdenum transferred to the solution, in percent, was 96%. The solution contains only potassium molybdate, a purity of at least 99.9%. Analysis of the solution by the X-ray fluorescence method showed the presence of only potassium and molybdenum ions and the absence of other cations.

Example 1.2 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

leaching agent concentration 0.100 mol / l; processing temperature 90 ° C.

The amount of molybdenum-containing product in terms of molybdenum oxide was 2.47 g in the extract, the molybdenum yield was 95.6%, and the purity was 99.9%.

Example 1.3 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

potassium hydroxide is used as the leaching agent, the concentration of the leaching agent is 0.149 mol / l, the treatment temperature is 90 ° C, and the treatment (stirring) time is 10 hours.

The amount of molybdenum-containing product in terms of molybdenum oxide was 2.44 g in the extract, the molybdenum yield was 95.3%, and the purity was 99.9%.

Example 1.4 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

The extraction was carried out from a spent catalyst KDOM-08, Russia, containing 4.76 g of molybdenum oxide, the concentration of leaching agent 0.725 mol / l, the processing temperature of 90 ° C.

The amount of molybdenum-containing product in terms of molybdenum oxide was 4.58 g in the extract, the molybdenum yield was 96.3%, and the purity was 99.9%.

Example 1.5 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

The extraction is carried out from a KDOM catalyst, Russia, containing 2.05 g of molybdenum oxide, a solution of sodium carbonate concentration of 0.725 mol / L is used as a leaching agent.

The amount of molybdenum-containing product in terms of molybdenum oxide was 1.99 g in the extract, the yield of molybdenum was 97.1%, and the purity was 99.9%.

Example 1.6 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

the concentration of leaching agent 1,090 mol / L.

The amount of molybdenum-containing product in terms of molybdenum oxide was 2.54 g in the extract, the yield of molybdenum was 99.3%, and the purity was 99.9%.

Example 1.7 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

The extraction is carried out from a KDOM catalyst containing 1.80 g of molybdenum oxide, the mass ratio of the solution of the leaching agent (potassium carbonate) to the catalyst is 10: 1, the concentration of the leaching agent is 1.090 mol / L, the treatment (stirring) time is 4 hours.

The amount of molybdenum-containing product in terms of molybdenum oxide was 1.66 g in the extract, the molybdenum yield was 92.1%, and the purity was 99.9%.

Example 1.8

fully repeats example 1.1, sodium hydroxide is used as the leaching agent, processing temperature 95 ° C, processing time (stirring) 10 hours.

The amount of molybdenum-containing product in terms of molybdenum oxide was 2.36 g in the extract, the molybdenum yield was 92.0%, and the purity was 99.9%.

Example 1.9 The extraction of molybdenum is carried out as in example 1.1 with the following changes:

The extraction is carried out from a CDES catalyst containing 2.60 g of molybdenum oxide, the mass ratio of the solution of the leaching agent (potassium carbonate) to the catalyst is 0.5: 1.

The amount of molybdenum-containing product in the extract was 2.46 g, the yield of molybdenum was 94.6%, and the purity was 99.9%.

Examples 2. Extraction of cerium (table 2)

Example 2.1

After leaching of molybdenum according to example 1.1. and washing, the spent catalyst S6-34 is dried in an oven at a temperature of 105-120 ° C for 5-6 hours and is subsequently used to extract cerium.

A 500 ml cylinder of concentrated hydrochloric acid is poured into a chemical heat-resistant glass and a weighed portion of 100.00 g of spent catalyst is weighed on an analytical balance after molybdenum is recovered, while the mass ratio of acid to catalyst is 5.95: 1. The CeO ₂ content in the Basf brand S6-34 catalyst, determined by X-ray fluorescence, was 9.60 g. The sample was dissolved at t = 30 ° C and stirred with a magnetic stirrer at a speed of 300-400 rpm for 60 minutes. To the resulting solution is poured 1000 ml of distilled water (2-fold volume) and heated to a temperature of 95-100 ° C. The solution was evaporated to a volume of 500 ml.

The solution obtained after evaporation is filtered from undissolved impurities on a vacuum filter. As a filter using paper "white tape".

After filtering, the solution is placed in a heat-resistant glass with a volume of 2 l, with a magnetic stirrer, stirring is turned on, the speed is set to 150-200 rpm. With stirring, a 12.5% ammonia solution is poured into the solution until a pH of 4 ± 0.5 is reached. The pH of the solution is controlled using a pH meter equipped with a glass and silver chloride electrode. As a result of the deposition, a thick, gelatinous brown solution is obtained, which is used later in the deposition of cerium oxalate.

After neutralization, the solution is heated on an electric stove to a temperature of 95 ° C and stirring is switched on at a speed of 250-300 rpm. 50 ml of a 5% solution of calcium chloride (mass ratio of calcium: catalyst 1.8: 100) and 1000 ml of a 20% solution of oxalic acid (mass ratio of oxalic acid: catalyst 5: 1) are successively added to the solution. After adding all the components, stirring is carried out at a temperature of 95 ° C for 3 hours, after the lapse of time the solution is removed from the tile and left to settle for 6 hours. After precipitation, the solution is drained from the surface of the precipitate onto a filter, filtered on a vacuum filter. As a filter, filter paper "blue tape" is used. The precipitate is washed on the filter two times in portions of 500 ml of a 1% solution of oxalic acid. The resulting precipitate, ten-water cerium oxalate, is a product that subsequently goes to the drying stage. The filtrate - a solution of iron chloride goes for further processing.

The cerium oxalate obtained after filtration and washing was dried in an oven at a temperature of 90 ° C for 2 hours. The mass of the dried precipitate was 19.0 g.

After cooling to room temperature, the loss on ignition and the content of cerium and other elements in the oxalate are determined. To determine the losses during calcination in a porcelain crucible, previously calcined and brought to a constant weight, cerium oxalate is poured and weighed to the nearest 0.1 mg, after which it is calcined at 800 ° C for 2 hours. After cooling, the crucible with the calcined precipitate is again weighed with the same accuracy. Loss on ignition (p.p.p.) is calculated as the ratio of the difference in mass of the sample before and after calcination to the mass of the sample taken. Loss on ignition determined by this method amounted to 53.53%. During calcination, the oxalates of cerium and calcium are converted to the corresponding oxides.

The content of elements in the catalyst and in cerium oxalate was determined by x-ray fluorescence analysis. For analysis, the catalyst was ground and dried to constant mass, and the composition of cerium oxalate was determined in the sample after calcination. According to the results, 9.60 g of CeO _{2 was} contained in 100 g of the initial catalyst sample, and cerium oxalate obtained from it contained 99.5% CeO ₂ and 0.5% CaO in the calcined residue, which characterizes the purity of cerium oxalate. Thus, the purity of the product was 99.5%.

The yield is considered as the ratio of the cerium content in the catalyst (in terms of its compound) to the cerium actually recovered. The yield calculation was carried out as follows.

From 100 g of the catalyst, 19.00 g of 10 aqueous cerium oxalate was obtained. The mass of oxides after calcination of oxalates is equal to 19.00 * (100-53.53) / 100 = 8.83 g. The content of cerium dioxide in the calcined product is 99.5%, therefore, the mass of CeO ₂ is 8.83 * 0.995 = 8 , 79 g. The yield was: 8.79 * 100 / 9.60 = 91.6%.

Example 2.2 Carried out analogously to example 2.1. with the following changes:

The catalyst after extraction of molybdenum is not dried, determine the moisture content of the catalyst, which amounted to 20.15%.

Taking into account humidity, the mass of the catalyst taken for cerium extraction was 125.2 g, which, in terms of the dried catalyst, is equivalent to 100 g of the catalyst, the cerium dioxide content in the catalyst is the same as in Example 2.1 - 9.60 g.

The mass ratio of hydrochloric acid to the catalyst was 5.00: 1 (420 ml of concentrated acid added, density 1.19 g / ml);

The temperature of dissolution of the catalyst in acid 95 ° C, the dissolution time of 30 minutes;

The ratio of the volume of hydrochloric acid and added water is 1: 1;

The concentration of the added ammonia solution is 25%, it is added until a pH of 4 ± 0.5 is reached;

The mass ratio of calcium to catalyst 1: 100 (added 50 ml of 2.78% calcium chloride);

The cerium deposition time was 24 hours;

Loss on ignition was 52.80%.

From 125.2 g of a wet catalyst, 19.02 g of 10 aqueous cerium oxalate was obtained. The mass of oxides after calcination of oxalates is equal to 19.02 * (100-52.80) / 100 = 8.98 g. The content of cerium dioxide in the calcined product is 98.5%, therefore, the mass of CeO ₂ is 8.98 * 0.985 = 8.84 d. The yield was: 8.84 * 100 / 9.60, = 92.1%.

Example 2.3 carried out analogously to example 2.1. with the following changes:

The mass ratio of hydrochloric acid to the catalyst was 5.00: 1 (420 ml of concentrated acid added, density 1.19 g / ml);

The dissolution temperature of the catalyst in acid 60 ° C, the dissolution time of 40 minutes;

The ratio of the volume of hydrochloric acid and added water is 1: 1;

The concentration of the added ammonia solution is 5%, it is added until a pH value of 4 ± 0.5 is reached;

The mass ratio of calcium to catalyst 5: 100 (added 100 ml of 17.5% calcium nitrate); The mass ratio of calcium to catalyst 5: 100;

Cerium deposition time 4 hours;

Loss on ignition was 52.08%.

From 100 g of the catalyst, 18.56 g of 10 aqueous cerium oxalate was obtained. The composition of the oxides after calcination of oxalate: CeO ₂ - 98.0%, CaO - 0.8%, Fe ₂ O ₃ - 1.2%. The mass of oxides after calcination of oxalates is 18.56 * (100-52.08) / 100 = 8.89 g. The content of cerium dioxide in the calcined product is (purity) 98.0%, therefore, the mass of CeO ₂ is 8.89 * 0. 98 = 8.71 g. The yield was: 8.71 * 100 / 9.6 = 90.8%.

Example 2.4

It is carried out in the conditions of example 2.1 with the following changes.

As a spent catalyst for the dehydrogenation of isoamylenes into isoprene, KDOM-08 is used, the composition of which is as follows:

Element Oxide Content,% mass. Fe ₂ O ₃ 75.00 Moo ₃ 3,54 CeO ₂ 11.40 K ₂ O 3.13 CaO 3,51 MgO 3.40

The mass ratio of hydrochloric acid to the catalyst was 10.00: 1 (840 ml of concentrated hydrochloric acid with a density of 1.19 g / ml was added);

The temperature of dissolution of the catalyst in acid 30 ° C, the dissolution time of 90 minutes;

The concentration of the added ammonia solution is 25%, it is added until a pH of 4 ± 0.5 is reached;

The deposition time of cerium is 20 hours;

Loss on ignition was 52.03%.

From 100 g of the catalyst, 22.50 g of ten-cerium oxalate of cerium was obtained. The composition of the oxides after calcination of oxalate: CeO ₂ - 98.8%, CaO - 0.5%, Fe ₂ O ₃ - 0.7%. The degree of purity is 98.8%.

The mass of oxides after calcination of oxalates is 22.5 * (100-52.03) / 100 = 0.79 g. The cerium dioxide content in the calcined product is 98.8%, therefore, the mass of CeO ₂ is 10.79 * 0.988 = 10 , 66 g. The yield was: 10.66 * 100 / 11.41 = 93.4%.

Example 2.5 Similar to example 2.1, differs in the following:

Use the spent catalyst KDOM of the following composition:

Element Oxide content,% mass. Fe ₂ O ₃ 76.3 Moo ₃ 2.05 CeO ₂ 7.10 K ₂ O 8.85 CaO 3.90 MgO 1.80

Loss on ignition was 52.87%.

The initial catalyst sample contained 7.10 g CeO ₂ , and the calcined residue obtained from it contained cerium oxalate in terms of oxides CeO ₂ - 98.05%, CaO - 0.85%, Fe ₂ O ₃ - 1.1% . Thus, the purity of the product was 98.05%.

From 100 g of the catalyst, 13.84 g of 10 aqueous cerium oxalate was obtained. The mass of oxides after calcination of oxalates is 13.84 * (100-52.87) / 100 = 6.52 g. The cerium dioxide content in the calcined product is 98.05%, therefore, the mass of CeO ₂ is 6.52 * 0.9805 = 6.40 g. The yield was: 6.40 * 100 / 7.1 = 90.0%.

Example 2.6. Similar to example 2.1 with the following changes.

The mass ratio of hydrochloric acid to the catalyst was 5.00: 1 (420 ml of concentrated acid added, density 1.19 g / ml);

The dissolution temperature of the catalyst in acid is 40 ° C, the dissolution time is 50 minutes;

The ratio of the volume of hydrochloric acid and added water is 1: 1;

The mass ratio of oxalic acid to the catalyst is 10: 1; added 1000 g of a saturated solution of oxalic acid;

Cerium deposition time 24 hours;

Loss on ignition was 53.34%.

The initial sample of the catalyst contained 9.60 g of CeO ₂ , and the calcined residue obtained from it contained cerium oxalate in terms of CeO ₂ oxides - 98.1%, CaO - 1.2%, Fe ₂ O ₃ - 0.7% . Thus, the purity of the product was 98.1%.

From 100 g of the catalyst, 18.90 g of 10 aqueous cerium oxalate was obtained.

The mass of oxides after calcination of oxalates is equal to 18.90 * (100-53.34) / 100 = 8.82 g. The content of cerium dioxide in the calcined product is 98.1%, therefore, the mass of CeO ₂ is 8.82 * 0.981 = 8 , 65 g. The yield was: 8.65 * 100 / 9.6 = 90.1%.

Example 2.7 Similar to example 2.5 with the following changes.

The temperature of dissolution of the catalyst in acid 90 ° C, the dissolution time of 30 minutes;

The mass ratio of a solution of hydrochloric acid and catalyst 5: 1;

The concentration of the ammonia solution is 5%;

The mass ratio of calcium to catalyst 1: 100;

The mass ratio of oxalic acid to the catalyst is 10: 1; added 1000 g of a saturated solution of oxalic acid;

Cerium deposition time 24 hours;

Loss on ignition was 53.03%.

The initial catalyst sample contained 7.10 g CeO ₂ , and the calcined residue obtained from it contained cerium oxalate in terms of CeO ₃ oxides - 98.5%, CaO - 0.6%, Fe ₂ O ₃ - 0.9% . Thus, the purity of the product was 98.5%.

From 100 g of the catalyst, 14.54 g of 10 aqueous cerium oxalate was obtained.

The mass of oxides after calcination of oxalates is equal to 14.54 * (100-53.03) / 100 = 6.83 g. The content of cerium dioxide in the calcined product is 98.5%, therefore, the mass of CeO ₂ is 6.83 * 0.985 = 6 , 72 g. The yield was: 6.72 * 100 / 7.1 = 94.7%.

Example 2.8. Similar to example 2.1 with the following changes.

The mass ratio of hydrochloric acid to the catalyst was 10.00: 1 (840 ml of concentrated acid added, density 1.19 g / ml);

The mass ratio of calcium to catalyst 1: 100;

The mass ratio of oxalic acid to the catalyst is 10: 1; added 1000 g of a saturated solution of oxalic acid;

Cerium deposition time 12 hours;

Loss on ignition was 52.45%.

The initial sample of the catalyst contained 9.60 g of CeO ₂ , and the calcined residue obtained from it contained cerium oxalate in terms of CeO ₂ oxides - 98.8%, CaO - 0.5%, Fe ₂ O ₃ - 0.7% . Thus, the purity of the product was 98.8%.

From 100 g of the catalyst, 19.48 g of 10 aqueous cerium oxalate was obtained.

The mass of oxides after calcination of oxalates is equal to 19.48 * (100-52.45) / 100 = 9.26 g. The cerium dioxide content in the calcined product is 98.8%, therefore, the mass of CeO ₂ is 9.26 * 0.988 = 9 , 15 g. The yield was: 9.15 * 100 / 9.6 = 95.3%.

Example 2.9. Similar to example 2.1, differs in that

Use the spent catalyst KDES of the following composition:

Element Oxide Content,% mass. Fe ₂ O ₃ 71.6 Moo ₃ 2.6 CeO ₂ 10.1 K ₂ O 9.7 CaO 2,4 MgO 2,8 TiO ₂ 0.6 V ₂ O ₅ 0.2

Loss on ignition was 52.20%.

The initial catalyst sample contained 10.10 g CeO ₂ , and the calcined residue of cerium oxalate obtained from it contained 98.7% CeO ₂ 0.6 CaO -, Fe ₂ O ₃ - 0.7% in terms of oxides. Thus, the purity of the product was 98.7%.

From 100 g of the catalyst, 19.95 g of 10 aqueous cerium oxalate was obtained. The mass of oxides after calcination of oxalates is equal to 19.95 * (100-52.20) / 100 = 9.54 g. The cerium dioxide content in the calcined product is 98.7%, therefore, the mass of CeO ₂ is 9.54 * 0.987 = 9 , 41 g. Yield was: 9.41 * 100 / 10.2 = 92.3%.

Claims (19)

1. A method of extracting molybdenum and cerium from spent iron oxide catalysts for the dehydrogenation of olefin and alkyl aromatic hydrocarbons, in which the extraction of molybdenum and cerium is carried out in two stages, the first stage is the extraction of the molybdenum compound, after which the second stage of processing the catalyst residues with the extraction of the cerium compound is carried out, this in the first stage
- spend grinding the spent catalyst;
- to the crushed catalyst add a solution of leaching agent in a mass ratio to the spent catalyst (0.5-10): 1 in a concentration of not less than 0.1 mol / l;
- spend mixing the suspension for 4-10 hours at a temperature of 90-95 ° C;
- after mixing is carried out, the mixture is filtered to precipitate;
- the precipitate is washed with water to wash the residual molybdenum;
- prepare a mixture of filtrate and washings of sediment containing molybdenum - a solution of alkali metal molybdate;
- the resulting mixture is evaporated to obtain a marketable product, after which the second stage of extraction of the cerium compound is carried out, for which
- spend the complete dissolution of the remainder of the crushed catalyst in concentrated hydrochloric acid;
- water is added to the resulting solution, then evaporating it to the original volume of the solution;
- after evaporation, the insoluble part is separated by filtration, separating the insoluble impurities;
- the solution remaining after filtration is neutralized until a pH of 3.5-4.5 is obtained, while controlling the pH;
- after such neutralization, the solution is heated to 90-100 ° C with stirring;
- after reaching the indicated temperature, a solution of calcium salt in a mass ratio of calcium: catalyst from 1: 100 to 5: 100 and a saturated solution of oxalic acid in a mass ratio to catalyst from 5: 1 to 10: 1 are successively added to the solution;
- after adding all the components are mixing at a temperature of 70-100 ° C for 2-6 hours;
- spend the exposure of the solution to precipitate the cerium compound for 4-24 hours at room temperature;
- after receiving the precipitate, it is separated from the mother liquor by filtration, draining the solution from the surface of the precipitate onto the filter with a pore size of the filter material of not more than 2 microns;
- the filter cake is washed from the iron compound and dried to constant weight to obtain the cerium compound. 2. The method according to claim 1, characterized in that as the leaching agent use a solution of alkali or carbonate of an alkali metal, preferably potassium. 3. The method according to claim 1, characterized in that the stirring of the suspension for 4-10 hours is carried out with the exception of the evaporation of water at a temperature of 90-95 ° C. 4. The method according to claim 1, characterized in that the mixture obtained from the filtrate and washings of the precipitate containing molybdenum is evaporated 2 times at a temperature of 70-100 ° C to obtain a marketable product with a molybdenum content of 5-6 g / l in solution . 5. The method according to claim 1, characterized in that the dissolution of the residue of the crushed catalyst in concentrated hydrochloric acid is carried out by stirring at a temperature of 30-95 ° C for 30-90 minutes 6. The method according to claim 1, characterized in that equal to two times the volume of water is added to the solution of the residue of the crushed catalyst in concentrated hydrochloric acid and the mixture is heated to 95-100 ° C. 7. The method according to claim 1, characterized in that to neutralize the solution after filtering using a 5-25% solution of ammonia. 8. The method according to claim 1, characterized in that the filter cake is washed with a 1-2% solution of oxalic acid, preferably with stirring, to obtain a ten-cerium oxalate of cerium. 9. The method according to claim 1, characterized in that the ten-cerium oxalate of cerium is sent for drying in an oven at a temperature of 90 ° C to constant weight to obtain cerium oxalate. 10. The method of extraction of molybdenum from spent iron oxide catalysts for the dehydrogenation of olefinic and alkylaromatic hydrocarbons, which consists in the following:
- spend grinding the spent catalyst;
- to the crushed catalyst add a solution of leaching agent in a mass ratio to the spent catalyst (0.5-10): 1 in a concentration of not less than 0.1 mol / l;
- spend mixing the suspension for 4-10 hours at a temperature of 90-95 ° C;
- after mixing is carried out, the mixture is filtered to precipitate;
- the precipitate is washed with water to wash the residual molybdenum;
- prepare a mixture of filtrate and washings of sediment containing molybdenum - a solution of alkali metal molybdate;
- the resulting mixture is evaporated to obtain a marketable product. 11. The method according to claim 10, characterized in that as a leaching agent use a solution of alkali or carbonate of an alkali metal, preferably potassium. 12. The method according to claim 10, characterized in that the suspension is stirred for 4-10 hours with the exception of the evaporation of water at a temperature of 90-95 ° C. 13. The method according to claim 10, characterized in that the resulting mixture from the filtrate and wash water of the precipitate containing molybdenum is evaporated 2 times at a temperature of 70-100 ° C to obtain a marketable product with a molybdenum content of 5-6 g / l in solution . 14. The method of extraction of cerium from spent iron oxide catalysts for the dehydrogenation of olefinic and alkylaromatic hydrocarbons, which consists in the following:
- conduct complete dissolution of the crushed catalyst in concentrated hydrochloric acid;
- water is added to the resulting solution, then evaporating it to the original volume of the solution;
- after evaporation, the insoluble part is separated by filtration, separating the insoluble impurities;
- the solution remaining after filtration is neutralized until a pH of 3.5-4.5 is obtained, while controlling the pH;
- after such neutralization, the solution is heated to 90-100 ° C with stirring;
- after reaching the specified temperature, a solution of calcium salt in a mass ratio of calcium: catalyst from 1: 100 to 5: 100 and a saturated solution of oxalic acid in a mass ratio of oxalic acid to catalyst from 5: 1 to 10: 1 are successively added to the solution;
- after adding all the components are mixing at a temperature of 70-100 ° C for 2-6 hours;
- spend the exposure of the solution to precipitate the cerium compound for 4-24 hours at room temperature;
- after receiving the precipitate, it is separated from the mother liquor by filtration, draining the solution from the surface of the precipitate onto the filter with a pore size of the filter material of not more than 2 microns;
- the filter cake is washed from the iron compound and dried to constant weight to obtain the cerium compound. 15. The method according to 14, characterized in that the dissolution of the residue of the crushed catalyst in concentrated hydrochloric acid is carried out by stirring at a temperature of 30-95 ° C for 30-90 minutes 16. The method according to 14, characterized in that in the solution of the residue of the crushed catalyst in concentrated hydrochloric acid is added water from an equal to two times the volume and the mixture is heated to 95-100 ° C. 17. The method according to 14, characterized in that to neutralize the solution after filtering using a 5-25% solution of ammonia. 18. The method according to 14, characterized in that the filter cake is washed with a 1-2% solution of oxalic acid, preferably with stirring, to obtain a ten-cerium oxalate of cerium. 19. The method according to 14, characterized in that the ten-cerium oxalate of cerium is sent for drying in an oven at a temperature of 90 ° C to constant weight to obtain cerium oxalate.