The catalyst for sulfur by the claus process and the method of its preparation

 

(57) Abstract:

The present invention relates to catalysts for sulfur by the Claus process and ways of cooking. The catalyst contains in its composition, wt.%:CaCO3and 90-99 solid solution of titanium oxide and rare earth elements (REE), having the composition of Ti(REEx)O(2+1.5 x)where 0,174x0,027. The catalyst was prepared by simultaneous processing of titanium tetrachloride and a mixture of REE chlorides aqueous solution or suspension of an alkaline agent, which is injected calcium carbonate, taken in a certain amount, with the subsequent stages of the precipitate, wash it from calcium chloride, separation of the catalyst mass filtering, molding, drying and calcination, or drying, calcination and tableting. The technical result of the invention consists in a higher activity of the proposed catalyst in the hydrolysis of organic sulfur compounds in comparison with the prototype, the simplified preparation method of the catalyst due to a sharp reduction in the number of technological operations and the exclusion of emissions of nitrogen oxides. 2 S. p. f-crystals, 1 table.

The invention relates to the field of inorganic chemistry, in the hour of the industry at facilities Claus.

The Claus process is designed to produce elemental sulfur by oxidation of hydrogen sulfide with sulfur dioxide by the reaction:

2H2S + SO2A 3/n + H2O (1).

In gases arriving at the installation Claus, along with hydrogen sulfide and sulfur dioxide usually contains up to 2% vol. one organic sulfur compounds CS2and COS. One of the most important requirements for the catalysts of the Claus process is the activity in the reactions of hydrolysis of these compounds:

CS2+ 2 H2O F CO2+ 2 H2S (2),

COS + H2O A CO2+ H2S ( 3).

The result of reactions (2) and (3) hydrogen is formed, which is oxidized by sulfur dioxide according to reaction (1), which leads to increased yield of the target product is elemental sulfur. At low catalyst activity in the reaction of hydrolysis of CS2and COS pass through the catalytic converters and come with tail gas installation Claus furnace, where it is burned with the formation of SO2. Thus, the high activity of the catalyst in the Claus process is the hydrolysis reaction CS2and COS allows to increase the yield of elemental sulfur and at the same time to reduce emissions of SO2in atmosphere.

The catalyst shows high activity in the oxidation reaction of hydrogen sulfide with sulfur dioxide, but does not have activity in the hydrolysis reactions of organic sulfur compounds.

Known dioxide based catalyst Claus process is derived from the ortho - and meta-metatitanate acids or oxyhydroxide titanium. The disadvantage of this catalyst is low activity in the hydrolysis reactions of organic sulfur compounds. Thus, the degree of transformation CS2and COS at 300oC and contact time 4 does not exceed 28% [2].

Known catalyst for Claus process, containing a mixture of oxides of titanium, zirconium and cerium in the ratio of 62.3 : 23,2 : 14,5. The catalyst was prepared separate deposition oxyhydroxides titanium, zirconium and cerium by interaction of the basic sulfates of titanium, zirconium and cerium nitrate with an alkaline agent, mixing and handling of wet catalyst weight nitric acid at a ratio of (oxihydroxide metals) : (H2O) : (HNO3= 69 : 23 : 8 with subsequent stages of forming, drying and calcination.2at a temperature of 340oC and the contact time between 0.5 and 1.0 is 63 and 95%, respectively [3].

The disadvantage of this catalyst is relatively low activity in the hydrolysis reactions of organic sulfur compounds at low contact times.

The disadvantages of the method of preparation of the catalyst are:

separate the three precipitation oxyhydroxides titanium, zirconium and cerium, leading to complication of the technology;

introduction to catalyst weight nitric acid, and therefore require expensive corrosion-resistant equipment;

the emissions of significant quantities of nitrogen oxides resulting from the decomposition of nitric acid by calcination of the catalyst.

The closest in technical essence and the achieved effect to the proposed technical solution is the catalyst contains from 65 to 98,5 wt. % of titanium dioxide (oxide component) and 1.5 to 35 wt.% sulphate of calcium, strontium or barium (connection alkaline earth element).

The method of its preparation is getting oxyhydroxide titanium processing of titanium tetrachloride aqueous solution of an alkaline agent, from the powder for 30 min with water and carboxymethyl cellulose, extrusion of this mixture, drying the extrudate at 110oC for 8 h, annealing at 450-500oC for 2-7 h, impregnating the product with a solution of ammonium sulfate or sulfuric acid, drying for 4 h at 110oC, the subsequent impregnation of the nitrate of the alkaline earth element, drying at 110oC for 4-12 h and calcination at 450oC for 1-2 h

The catalyst provides outputs sulfur according to reaction (1), close to thermodynamic equilibrium. Conversion CS2at a temperature of 260oC and a contact time of 1 s is 72% at a temperature of 340oC and a contact time of 3 s - 99% [4] (prototype).

The disadvantage of this catalyst is relatively low activity in the hydrolysis reactions of organic sulfur compounds at low temperatures and low contact times.

The disadvantages of the method of preparation of the catalyst are:

the multistage and the complexity of technology;

large energy costs of multiple stage drying and calcination of a catalyst mass;

the presence of emissions of nitrogen oxides (about 100 kg per 1 ton of catalyst).

Comparison of data on activity in the oxidation reaction of hydrogen sulfide with sulfur dioxide is Eski same. Choice as a prototype of the catalyst according to the patent [4] due to the fact that the proposed catalyst as well as the prototype contains an oxide component and connection alkaline earth element. In addition, the production of the catalyst of the prototype developed in industry (catalyst CRS-31, the Firm Rhone-Poulenc), it can be used for comparison of catalytic activity of the prototype and the proposed catalyst in the same experimental conditions.

The technical task of the invention is to provide a catalyst for sulfur by the Claus process, with increased activity in the hydrolysis reactions of organic sulfur compounds, and a method of its preparation, allowing to simplify the production technology of the catalyst and to eliminate the formation and emissions of nitrogen oxides.

The technical problem solved by the claimed catalyst containing oxide component and connection alkaline earth element, characterized in that the oxide component of the catalyst comprises a solid solution of titanium oxide and rare earth elements (REE), having the composition of Ti(REEx)O(2+1.5 x)where 0,174 0,027 x, and as a connection deliciosamente Solid solution of titanium oxides and REE, the appropriate composition of Ti(REEx)O(2+1.5 x)where 0,174 x - 0,027 Else.

The technical problem is also solved by a method of its production, including the production of oxyhydroxide titanium processing of titanium tetrachloride aqueous solution of an alkaline agent, molding, drying and calcination, wherein while receiving oxyhydroxide titanium receive oxyhydroxide rare earth elements (REE) by joint processing of titanium tetrachloride and REE chlorides aqueous solution or suspension of an alkaline agent, which is injected calcium carbonate, taken to its content in the finished catalyst was 1-10 wt.%, the quantity of titanium tetrachloride and chlorides of rare-earth elements taken from the calculation that the ratio of titanium oxides and REE in the solid solution was within(73,7-94,7) : (5,3-26,3) and the process is conducted at a ratio of components responsible for the content in the catalyst, wt. %:

Calcium carbonate is 1 to 10

Solid solution of titanium oxides and REE corresponding to the composition of Ti(REEx)O(2+1.5 x)where 0,174 0,027 x - Rest.

The invention consists in that the catalyst for sulfur by the Claus process contains calcium carbonate and solid Rast is onenow, wt. % of: calcium carbonate 1-10, solid solution of titanium oxides and REE else.

Distinctive features of the process of preparation of the catalyst are :

simultaneous receipt of oxyhydroxides titanium and REE by joint processing of titanium tetrachloride and REE chlorides aqueous solution or suspension of alkali agent;

the pretreatment with calcium (calcium carbonate) in an aqueous solution or suspension of an alkaline agent.

These distinctive features make it possible to obtain a catalyst mass at one stage.

Obtaining catalysts is as follows.

In the reactor pour a certain amount of an aqueous solution or suspension of an alkaline agent, which is added calcium carbonate based, so that in the finished catalyst contained 1-10 wt.% CaCO3and under stirring, the suspension is injected calculated amount of REE chlorides and titanium tetrachloride, providing the neutralization of the alkaline agent. As REE chlorides may be used, for example, a mixture containing chlorides of cerium, lanthanum, neodymium, praseodymium, samarium, or any of the chlorides of rare-earth elements separately.

When interacting chloride is Sadok, and calcium chloride dissolved in the mother liquor. The number of TiCl4and chlorides of rare-earth elements taken from the calculation that the ratio (TiO2): (REE oxides in solid solution was within(73,7- 94,7) : (5,3 - 26,3).

The precipitate containing calcium carbonate, oxyhydroxide titanium and rare-earth elements, separated by filtration and washed with water to remove calcium chloride, and then the catalyst mass is separated by filtration, add a solution of carboxymethyl cellulose (CMC) at the rate of 0.5 to 1.0 wt.% CMC on the calcined catalyst, dried and molded in the form of extrudates, which are dried at 110-120oC for 2 h and calcined at 450oC for 4 h, or obtained catalyst mass after filtration, is dried and calcined under the same conditions, and then tabletirujut.

When the joint deposition of oxyhydroxides titanium and REE by the described method is a uniform distribution of oxyhydroxides REE in oxihydroxide titanium. Subsequent stages of drying and calcination lead to the formation of a solid solution of titanium oxides and REE, with increased activity in the hydrolysis reactions of organic sulfur compounds. The presence of a catalyst 1-10 wt. % of calcium carbonate enhances the basic properties of the pic which makes it possible to increase the mechanical strength of the granules of the catalyst compared to extrudates.

The activity of the synthesized samples of the catalyst determine the hydrolysis reaction of carbon disulfide and the Claus reaction (oxidation of hydrogen sulfide with sulfur dioxide) on impulse installation chromatographic analysis of the reaction products. For experiments a portion of the catalyst (0.05-0.1 g) with a grain size of 0.25-0.50 mm is placed in a steel microreactor 70 mm length and 3 mm in diameter and is heated in a current of helium for 1 h

In determining the activity of the catalysts in the hydrolysis of organic sulfur compounds in the reactor microspace introducing the fluid mixture CS2: H2O = 1 : 2.

In determining the activity of the catalyst in the Claus reaction in the reactor, introducing a gaseous mixture of H2O : SO2= 2 : 1.

The contact time of the reactants with the catalyst is 0.05-0.25 s, the temperature in the reaction zone 300oC and 220oC, respectively, for the reactions of hydrolysis of carbon disulphide and oxidation of hydrogen sulfide with sulfur dioxide. Catalytic activity expressed in the form of the reaction rate constants are calculated by the equation Habgood and Basset (J. Phys. Chem. 1960, v. 64, p.769). The value of the reaction rate constants are calculated as the average of five measurements.

The invention is illustrated sledujushjuju 1 g of calcium carbonate, and when hashing enter 7.9 g of a mixture of chlorides of rare-earth elements containing, wt.%: cerium 55,4, lanthanum 26,8, neodymium 12,2, praseodymium 4.8 and Samaria to 0.8, and then 222,8 g of titanium tetrachloride. The obtained precipitate was separated by filtration, washed with water to remove the calcium chloride, the obtained catalyst mass is separated by filtration, mixed with 10 ml of 10% aqueous solution of CMC, dried to a moisture content of 40-60 wt.%, molded in the form of extrudates, dried at 110-120oC for 2 h and calcined at 450oC for 4 h, or the residue is separated by filtration, dried and calcined under conditions similar to those described above, and then tabletirujut.

Get the catalyst containing the wt. %: 1,0 CaCO3and 99,0 solid solution of oxides of the metals of the composition Ti(REE0,027)O2,04when the ratio of titanium oxides and REE, equal to 94.7: 5,3.

Example 2. The catalyst is prepared as described in example 1 with the difference that was charged to the reactor 1760 ml of 10% suspension of calcium hydroxide, which is added 2 g of calcium carbonate, with stirring enter of 29.1 g of cerium chloride and 209,1 g of titanium tetrachloride.

Get the catalyst containing the wt. % : 2,0 CaCO3and 98,0 solid solution of oxides of the metals of the composition Ti(Ce0,054)O2,10p is anomo in example 2 with the difference, what was charged to the reactor 1445 ml of 10% ammonium hydroxide solution and stirring is injected 22.9 grams of lanthanum chloride and 196,4 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 2,0 CaCO3and 98,0 solid solution of oxides of the metals of the composition Ti(La0,091)O2,14when the ratio of titanium oxide and lanthanum equal 84,4 : 15,6.

Example 4. The catalyst is prepared as described in example 1 with the difference that was charged to the reactor 1355 ml of 10% ammonium hydroxide solution, to which is added 3 g of calcium carbonate, with stirring enter 30,2 g of a mixture of chlorides of rare-earth elements and 182,4 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 3,0 CaCO3and 97.0 solid solution of oxides of the metals of the composition Ti (REEto 0.127O2,19when the ratio of titanium oxides and REE, equal to 79.2 : 20,8.

Example 5. The catalyst is prepared as described in example 1 with the difference that was charged to the reactor 1500 ml of 10% suspension of calcium hydroxide, which is added 5 g of calcium carbonate, with stirring enter 23.7 g of a mixture of chlorides of rare-earth elements and 179,5 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 5,0 CaCO3and 95,0 solid solution of oxides of the metals of the composition Ti(REE0 is similar to that described in example 2 with the difference, what was charged to the reactor 1588 ml of 10% suspension of calcium hydroxide, which is added 7.5 g of calcium carbonate, with stirring enter 20.6 g of cerium chloride, 10.8 g of lanthanum chloride and 185,5 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 7,5 CaCO3and 92,5 solid solution of oxides of the metals of the composition Ti(REE0,090)O2,14when the ratio of titanium oxides and REE, equal 84,4 : 15,6.

Example 7. The catalyst is prepared as described in example 1 with the difference that was charged to the reactor 1500 ml of 10% suspension of calcium hydroxide, which is added 10 g of calcium carbonate, with stirring enter 21,0 g of a mixture of chlorides of rare-earth elements of 180.5 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 10,0 CaCO3and 90.0 solid solution of oxides of the metals of the composition Ti(REE0,090)O2,14when the ratio of titanium oxides and REE, equal 84,4 : 15,6.

Example 8. The catalyst is prepared as described in example 1 with the difference that was charged to the reactor 1530 ml of 10% suspension of calcium hydroxide and stirring enter and 39.7 g of a mixture of chlorides of rare-earth elements to 173.3 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 10,0 CaCO3and 99,0 solid solution of oxides of metalcatalyzed prepared as described in example 1 with the difference, what was charged to the reactor 1520 ml of 10% suspension of calcium hydroxide and lead 40 g of a mixture of chlorides of rare-earth elements and 172,2 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 1,0 CaCO3and 99,0 solid solution of oxides of the metals of the composition Ti(REE0,180)O2,27when the ratio of titanium oxides and REE, equal 73,0 : 27,0.

Example 10. The catalyst is prepared as described in example 4 with the difference that was charged to the reactor 1744 ml of 10% suspension of calcium hydroxide and stirring enter to 7.35 g of a mixture of chlorides of rare-earth elements and RUR 219.4 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 3,0 CaCO3and 97.0 solid solution of oxides of the metals of the composition Ti(REE0,026)O2,38when the ratio of titanium oxides and REE, equal 95,0 : 5,0.

Example 11. The catalyst is prepared as described in example 1 with the difference that was charged to the reactor 1460 ml of 10% suspension of calcium hydroxide, which is added 12.5 g of calcium carbonate, with stirring enter 20,5 g REE chlorides and 175,5 g of titanium tetrachloride.

Get the catalyst containing the wt. %: 12,5 CaCO3and 87.5 solid solution of oxides of the metals of the composition Ti(REE0,090)O2,13when the ratio of titanium oxides and REE, equal 84,4 : Agregat 1665 ml of 10% suspension of calcium hydroxide, which does not add calcium carbonate, and stirring introduced 200 g of titanium tetrachloride.

Get the catalyst containing wt.%: 100,0 solid solution of oxides of the metals of the composition Ti(REE0,09)O2,14when the ratio of titanium oxides and REE, equal 84,4 : 15,6.

Listed in the table of data on catalytic activity and physico-chemical properties of the catalysts prepared by the described method and the prototype (dioxide based catalyst brand CRS-31 the company rhône-Poulenc, France) show that the samples of the catalyst obtained by the proposed method have a significantly higher activity in the hydrolysis reaction of carbon disulphide in comparison with the prototype. Thus, the rate constant for the hydrolysis reaction of carbon disulphide on the proposed catalyst 1.6-2.2 times higher (experiments 1-8) in comparison with the known catalyst (conversion of carbon disulfide at a temperature of 300oC and contact time of 0.25 s in experiments 1-8 on the proposed catalyst is 72-78 %, the catalyst prototype - 48%). In experiments 9-11 catalytic activity in the hydrolysis reaction of carbon disulphide is somewhat lower, due to the fact that the catalysts obtained in experiments 9 and 10, the ratio of the components in the solid solution (hydroxy what the CIO abroad optimum.

All catalyst samples prepared in the described manner, have a more developed surface in comparison with the prototype, thereby increasing their activity in the Claus reaction), providing a thermodynamically equilibrium yields of the target product, as well as high thermal stability (after calcination of the catalyst at a temperature of 800oC for 8 h activity is practically not reduced).

Prepared according to the procedure described in samples of catalyst pastes have high plasticity, therefore, the molded catalyst according to the variant extrusion smooth extrudates, which after drying and calcination have sufficient mechanical strength at a relatively low bulk weight (of 0.68-0.85 kg/l). The mechanical strength of the catalyst can be increased by using a variant of the molding pelletizing by the selection of the optimum compaction pressure, providing high strength and the necessary textural characteristics of the tablets.

The proposed method for the preparation of the catalyst in comparison with the prototype allows to simplify the technology of industrial production, reduce the cost of the catalyst due to re is Dios drying and calcination, associated with high costs of energy, as well as to exclude the formation and emission of oxides of nitrogen in the environment due to the fact that for the preparation of the catalyst is not used nitrates.

The use of the catalyst in the gas processing industry will allow due to the high activity in the reaction of hydrolysis of CS2and COS to increase the output of the gas sulfur and reduced sulfur dioxide emissions into the environment, because it is not subjected to hydrolysis CS2and COS you do with a tail gas installation Claus furnace, where it is burned to form sulfur dioxide, which is released into the atmosphere.

Above, causes obtain a technical result, which includes the creation of catalyst and method of its preparation.

The technical result of the invention consists in a higher activity of the proposed catalyst in the hydrolysis of organic sulfur compounds in comparison with the prototype, the simplified preparation method of the catalyst due to a sharp reduction in the number of technological operations and the exclusion of emissions of nitrogen oxides.

Literature.

Author's certificate shall elsto USSR N 2598094, class. B 01 J 53/36, 1987.

Patent USSR N 1213976, class B 01 J 21/06, 1986.5

1. The catalyst for sulfur by the Claus process containing oxide component and a calcium compound, characterized in that the oxide component of the catalyst comprises a solid solution of titanium oxide and rare earth elements (REE), having the composition of Ti(REEx)O2+1.5 xwhere 0,174 0,027 x, as well as compounds of rare-earth element, calcium carbonate with the following content, wt.

Calcium carbonate 1 10

Solid solution of titanium oxides and REE corresponding to the composition of Ti(REEx)O2+1.5 xwhere 0,174 x 0,027 Else

2. The preparation method of catalyst for sulfur by the Claus process, which includes the receipt of oxyhydroxide titanium processing of titanium tetrachloride aqueous solution of an alkaline agent, molding, drying and calcination, wherein while receiving oxyhydroxide titanium receive oxyhydroxide rare earth elements (REE) by joint processing of titanium tetrachloride and REE chlorides aqueous solution or suspension of an alkaline agent, which is injected calcium carbonate, taken to its content in the finished catalyst is s titanium and rare earth elements in solid solution was within 73,7 94,7 5,3 26,3, and the process is conducted at a ratio of components that provide the following content in the catalyst, wt.

Calcium carbonate 1 10

Solid solution of titanium oxides and REE corresponding to the composition of Ti(REEx)O2+1.5 xwhere 0,174 x 0,027 the otherc documents

 

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