MXPA00005564A - Catalyst for oxidizing so2 - Google Patents

Catalyst for oxidizing so2

Info

Publication number
MXPA00005564A
MXPA00005564A MXPA/A/2000/005564A MXPA00005564A MXPA00005564A MX PA00005564 A MXPA00005564 A MX PA00005564A MX PA00005564 A MXPA00005564 A MX PA00005564A MX PA00005564 A MXPA00005564 A MX PA00005564A
Authority
MX
Mexico
Prior art keywords
contact
catalyst
weight
carrier
active component
Prior art date
Application number
MXPA/A/2000/005564A
Other languages
Spanish (es)
Inventor
Egon Winkler
Georg Schmidt
Achim Hollnagel
Dietrich Werner
Nikola Anastasijevic
Franzferdinand Schuth
Annette Wingen
Original Assignee
Metallgesellschaft Ag 60323 Frankfurt De
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metallgesellschaft Ag 60323 Frankfurt De filed Critical Metallgesellschaft Ag 60323 Frankfurt De
Publication of MXPA00005564A publication Critical patent/MXPA00005564A/en

Links

Abstract

The invention relates to a catalyst for converting SO2 with molecular oxygen into SO3. The catalyst is suited for continuous operation at temperatures of 700°C and higher when said catalyst is comprised of a porous supporting material and an active component which is joined to the supporting material. The active component is made up of 10 to 80 wt.%iron. The supporting material is a BET-surface ranging from 100 to 2000 m2/g and comprises a SiO2 content of at least 90 wt.%. The weight ratio supporting material:active component ranges from 1:1 to 100:1.

Description

CATALYST FOR OXIDAR SQ2 TO SQ3 AND USING THE CATALYST IN A METHOD TO PRODUCE ACID SULFURIC DESCRIPTION This invention relates to a catalyst for reacting S02 with molecular oxygen to form SO3, and also to a process for producing sulfuric acid from S03 and water, wherein S03 is produced catalytically by reacting the S02 with molecular oxygen. The production of sulfuric acid from S02, which first of all catalytically oxidizes to SO3, is described in detail in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, vol. A25, pages 644 to 664. Known catalysts for the oxidation of S02, which contain for example V2O5 as active component, preferably operate at a temperature in the range from 380 to 620 ° C. Higher temperatures will damage the catalyst. This leads to the fact that the gas supplied to the catalyst must have an S02 content of no more than about 12% by volume, so that the isothermal capacity of the oxidation reaction can be easily controlled. DE-C-27 10 350 describes a catalyst for the conversion of S02 in S03, which operates at a temperature in the range of 600 to 800 ° C. The catalyst has a silicon oxide carrier with a tridymite structure and an active component containing iron, copper and an alkali metal. It is the fundamental object of the invention to create a catalyst suitable for continuous operation, whose capacity and stability are also ensured at temperatures of 700 ° C and above. Additionally, the catalyst must form the basis for a process for the production of sulfuric acid where gases with high concentration of SO2 are used. According to the invention, the catalyst comprises a porous carrier and an active component connected to the carrier, where the active component consists of 10 to 80% by weight of iron, the carrier has a BET surface at 100 to 2000 m2 / g and an SiO2 content of at least 90% by weight, and the weight ratio of the carrier: active component is in the range of 1: 1 to 100: 1. Since the carrier materials that can be used are silicates, in particular zeolites (e.g., beta-type zeolites), mesoporous silica gels (e.g., synthesized in accordance with U.S. Patent No. 3,556,725 or MCM-41 of Mobil Oil as pure material of Si02), also those mesoporous silica gels with up to 10% by weight of foreign elements (for example, boron), diatomaceous earth, amorphous Si02 or iliac or mesoporous alumni (for example, MCM-41 containing Mobil Oil aluminum). Advantageous carriers comprise, for example, from 90 to 100% by weight of a mesoporous zeolite or Si02. Details regarding mesoporous Si02 can also be found in WO-A-91/11390 and in "Microporous Materials" 10 (1997), pages 283-286. The iron-containing active component of the catalyst can consist in particular of at least 80% by weight of iron oxides. The active component may also contain sodium, potassium and / or cesium. The content of these alkali metals can be up to 10% by weight, based on the total weight of the catalyst. The active component of the catalyst may further include vanadium and / or sulfur compounds (eg, pyrosulfate). In the active component, the weight ratio V: Fe can be in the range from 1: 1 to 1.3: 1. For the sulfate content in the catalyst, from 1 to 7% by weight are recommended, based on the total weight of the catalyst. When the active component of the catalyst also contains copper, the Cu content will be up to 1% by weight of the Fe content. In the laboratory, the following catalysts were prepared: First catalyst: Mesoporous Si02 with an ordered pore structure, with amorphous walls and a pore system with a regular, hexagonal arrangement, with pore sizes between 2 and 8 nm (synthesized according to WO-) was used as starting material. A-91/11390). It has good thermal stability up to 1000 ° C and a BET surface area of approximately 1000 m2 / g. To 10 g of an aqueous solution of 25% C16H33N (CH3) 3C1a mixture of 1.8 g of liquid glass of soda (composition: 27.5% by weight of SiO2, 8.3% by weight of Na20, plus water), 1.3 g of SiO2 and 10 g of water was added in the space of 15 minutes. After stirring for 30 minutes, the suspension was heated for 48 hours in a polypropylene container with a screw thread at a temperature of 90 ° C. Then, it was filtered, washed and dried for 8 hours at 90 ° C. The dried mixture was heated to 550 ° C with a heating rate of 1 ° C per minute and kept at this temperature for 5 hours. One g of this product was thoroughly mixed with 3.5 ml of a Fe (No 3) solution of 0.95 mmol and subsequently dried for 2.5 hours at 90 ° C. The product was stirred for 1 hour and 25 g of distilled water, filtered, dried at 90 ° C and then heat treated as follows: heating at 400 ° C with an increase of 5 ° C per minute, maintenance at 400 ° C. C for 3 hours, then heating at 700 ° C with an increase of 5 ° C per minute, and subsequently maintaining at this temperature for 3 hours. The product had a BET surface area of 478 m2 / g, in weight ratio Si: Fe was 5: 1.
Second Catalyst: 3 g of commercial Si02 (BASF Dll-10) were added to a solution of 0.18 g of NH V03 in 20 ml of water. Then, 0.62 g of Fe (N03) 3 • 9H20, dissolved in 1 g of water, were added dropwise by rapid stirring. The product was filtered, washed, dried, heated to 800 ° C and maintained at 800 ° C for 24 hours. The weight ratio of Si: Fe: V is 33: 1: 1.3. In the same way, iron vanadate can be applied in carriers with a large surface area.
Third catalyst: Here, a zeolite type iron silicate (structural type beta-zeolite) is used as the carrier material; the iron silicate has a three-dimensional micropore system and has a large BET surface area of 600 m2 / g. A first aqueous solution was prepared as follows: 78.5 g of 40% t and 40% ethanolammonium hydroxide and 10.7 g of 40% hydrogen fluoride were added to 260.4 g of tetraethyl orthosilicate in a polypropylene vessel. 70% of this solution was separated, and to the remaining 30% of the first solution were added 3.6 g of FeCl3, dissolved in 9 g of water by stirring. Finally, 22.2 g of NH F and the previously separated solution were added. The preparation was heated for 24 hours at 70 ° C in the open vessel, and the dried gel was subsequently dissolved in 10 g of water.
In the inoculation with nuclei (beta-zeolite, 5% by weight) the product was crystallized in the course of 15 days in the poly tet rafluoroethylene vessel at 170 ° C. The product was heated to 200 ° C with 2 ° C per minute, kept at this temperature for 3 hours, then heated to 550 ° C with 5 ° C per minute, and kept at this temperature for 10 hours. The elemental analysis of the product revealed an atomic composition of H: Si: Fe: 0: F = 104: 60: 4.3: 178: 0.4. The samples of the three catalysts described above were tested in the laboratory, to determine their activity with respect to the oxidation of S02 to form S03. Of each catalyst, 0.5 ml of a fraction with particle sizes between 500 and 1000 μm in the nitrogen stream was maintained for three hours at 324 ° C for the purposes of activation. To measure the activity, 24.7 ml / min of a gas consisting of 20% by volume of S02, 22% by volume of 02, and 58% by volume of N2 were passed on the activated catalyst samples, where a time was obtained of residence of 1.2 seconds in the catalyst bed. The activity (percentage of converted S02) in temperature dependence is indicated in the following table The catalysts according to the invention are particularly suitable as pre-contact, to partially convert a gas with a high content of S02 to S03 and produce sulfuric acid, before the waste gas with a reduced SO2 content can be passed for example in a conventional production of sulfuric acid. The gas containing S02 and 02 and an SO2 content of 13 to 50% by volume and an oxygen content corresponding to a volume ratio of 02 / S02 of at least 1: 2 is supplied to a pre-contact stage , in the pre-contact stage, the gas and oxygen are passed through at least one bed (pre-contact bed) of a granulated catalyst (pre-contact), where the pre-contact has the characteristics described with prior, and the maximum temperature in the pre-contact is maintained in the range of 580 to 800 ° C. in the pre-contact stage, from 20 to 80% of the S02 supplied to S03 are converted, and from the pre-contact stage, a first gas mixture containing S03 is removed, which is cooled to temperatures of 50 to 300 ° C and is passed to at least one absorber, where in the absorber the first gas mixture is brought into direct contact with circulating sulfuric acid containing water, and a partial stream of sulfuric acid is removed. From the absorber, a second gaseous mixture containing S02 is removed, heated to a temperature of 380 to 600 ° C and with a concentration of S02 of 10 to 30% by volume is introduced in a subsequent oxidation stage, in which S02 is catalytically reacted with oxygen at temperatures of 480 to 770 ° C to form S03. In additional process steps, the S03 produced in the oxidation stage is processed to obtain sulfuric acid. In the subsequent oxidation step, usual catalysts are used. These catalysts can have active components, which for example consist of at least 5% by weight of V205.
The pre-contact stage can have, for example, at least two pre-contact beds, through which the gas flows one after the other. In an expeditious manner, the gas containing S02, 02 and SO3 is cooled between the pre-contact beds at temperatures of no more than 550 ° C. From the last pre-contact bed, a gas is removed after an intermediate absorption with not more than preferably 13% by volume of S02 and introduced into the subsequent oxidation stage. Now a process flow diagram will be explained, with reference to the drawing. A gas rich in S02, which has been mixed through line 3, containing 02 (for example, air) is supplied to the pre-contact stage 1 through line 2. The S02 content of the gas in line 2 it is in the range of from 13 to 50% by volume and mainly at least 15% by volume, and the gas has preferably preheated to temperatures of 350 to 500 ° C. In the variant of the process represented in the drawing, the pre-contact stage 1 consists of the fixed bed 4 of the temperature-resistant catalyst, which is referred to herein as pre-contact; the bed is referred to as a pre-contact bed 4. It may be convenient to provide a conventional catalyst (eg, vanadium contact) in the bed inlet 4 in a thin layer such as a so-called ignition layer, in order to increase the temperature in the gas is sufficient, so that the oxidation reaction in the pre-contact bed will begin in a completely immediate manner. At the entrance of the pre-contact bed 4 a volumetric relation of 02 / S02 of at least 0.5: 1 is ensured. In the pre-contact, an increase in temperature is effected by the oxidation reactions during SO3 formation. A first gaseous mixture containing S03 leaves the pre-contact stage 1 via line 6 with temperatures in the range of 580 to 800 ° C and preferably 600 to 700 ° C. This first gaseous mixture is cooled in the waste heat boiler 7 to temperatures of 50 to 300 ° C, where a valuable high pressure stream can be recovered from the water. The gaseous mixture then enters a first absorber 9, which is designed as a Venturi scrubber. The sulfuric acid coming from line 10 is sprayed into the gas, where the concentration of the sulfuric acid is increased by the absorption of SO3. The sulfuric acid formed in the first absorber 9 flows through line 11 to a collection tank 12, the excess sulfuric acid, whose concentration is usually in the range of 95 to 100% by weight, is removed via line 13 From the collection tank 12, through the circulation pump 15 and the line 16, sulfuric acid is supplied to the first absorber 9 and also to a second absorber 14, which is connected to the first absorber by the passage 17. The gas containing S03 flows through passage 17 to the second absorber 14 and thence upwards through a layer 19 of contact elements, which is sprayed with sulfuric acid from line 10a. Water is supplied via line 20, and the sulfuric acid discharged via line 21 also flows into collection tank 12. In practice, absorbers 9 and 14 can also be designed differently from that depicted in the drawing. . The gas flowing upward in the second absorber 14 releases droplets of sulfuric acid in the droplet separator 24, and then flows through line 25 to a heater 26, which increases the temperature of the gas to 380 to 500 ° C. The gas in line 27, here referred to as the second gas mixture, has the concentration S02 of 10 to 30% by volume. Due to this relatively low S02 concentration, it can be supplied to a conventional plant 28 of sulfuric acid, which employs the usual catalysts to oxidize S02 to form S03. The mode of operation of the structure of a conventional plant is known and described, for example in: Ullmann's Encyclopedia of Industrial Chemistry, as mentioned above.
Example: In the laboratory, the first catalyst described above is used to partially convert a gaseous mixture with the components indicated in column A of the subsequent table to form SO3: The data in the example has been calculated in part. The catalyst (pre-contact) has been formed in cylindrical extruders of approximately 8 mm in height and 6 mm in diameter. The catalyst is distributed over two trays (pre-contact beds) through which the gas mixture flows one after the other, each tray contains 40 g of catalyst with a bed height of 8 cm, the diameter of the tray is 4.7 cm. On the gas inlet side, each tray has a commercial vanadium catalyst to increase the temperature ("ignition layer"), so that the desired oxidation takes place in the pre-contact. The height of the ignition layer is 1 cm. 100 1 / h of the gaseous mixture of column A of the above table enters the ignition layer of the first tray with a temperature of 420 ° C and the pre-contact bed with a temperature of 550 ° C. A gaseous mixture with the composition indicated in column B of the above table leaves the first tray with a temperature of 670 ° C and is cooled to 420 ° C by indirect heat exchange. The cooled gas mixture is passed through the second tray, which like the first tray contains an ignition layer and a pre-contact bed. At the outlet of the second tray, the gaseous mixture has a temperature of 670 ° C and the composition indicated in column C of the previous table. When this gas mixture is cooled and the SO3 is removed through the absorption by means of sulfuric acid, as it is absorbed in conjunction with the drawing, a gaseous mixture is obtained with the composition indicated in column D of the previous table. According to the modern prior art (for example, Lurgi, Frankfurt), this gaseous mixture with an S02 content of 14.3% by volume can be processed in a main converter, where SO3 and sulfuric acid are formed and a waste gas with an SO2 content of less than 200 ppm.

Claims (7)

  1. CLAIMS 1. A catalyst for reacting S02 with molecular oxygen to form SO3, characterized in that the catalyst consists of a porous carrier and an active component connected to the carrier, where the active component consists of 10 to 80% by weight of iron, the carrier has a BET surface area of 100 to 2000 m2 / g and an SiO2 content of at least 90% by weight, and the weight ratio to the carrier: active component is in the range of 1: 1 to 100: 1.
  2. 2. The catalyst according to claim 1, characterized in that the active component consists of at least 80% by weight of iron oxides.
  3. 3. The catalyst according to claim 1 or 2, characterized in that the carrier consists of 90 to 100% by weight of zeolite.
  4. 4. The catalyst according to claim 1 or 2, characterized in that the carrier consists of 90 to 100% by weight of mesoporous silica.
  5. 5. A process for producing sulfuric acid from SO3 and water, wherein S03 is produced catalytically by reacting SO2 with molecular oxygen, characterized in that a gas containing S02 and 02 is supplied with an S02 content of 13 to 50% by volume and an oxygen content corresponding to a volumetric ratio of 02 / S02 of at least 1: 2, to a pre-contact stage, which in the pre-contact stage the gas and oxygen are passed to through at least one bed (pre-contact bed) of a granular catalyst (pre-contact), which pre-contact consists of a porous carrier and an active component connected to the carrier, where the carrier has a BET surface from 100 to 2000 m2 / g and an SiO2 content of at least 90% by weight, the active component consists of 10 to 80% by weight of iron, and the weight ratio carrier: active component e is in the range of 1: 1 to 100: 1, and the maximum temperature at the pre-contact is 580 to 800 ° C, which in the pre-contact stage, 20 to 80% of the supplied S02 are converted to S03, and from the pre-contact stage, a first gas mixture containing S03 is removed, a gas mixture that is cooled to a temperature of 50 to 300 ° C and is introduced into at least one absorber, that in the absorber the first gaseous mixture is brought into direct contact with circulating sulfuric acid containing water, and a partial stream of sulfuric acid is removed, that a second gas mixture containing SO2 it is removed from the absorber and heated to a temperature of 380 to 600 ° C, that the second gas mixture with a SO2 concentration of 10 to 30% by volume is introduced in a subsequent oxidation step, in which S02 is reacted catalytically with oxygen at temperatures of 480 to 770 ° C to form S03, and that the SO3 formed in the oxidation step is processed in additional process steps to form sulfuric acid. The process according to claim 5, characterized in that in the pre-contact stage, the gas containing S02 and 02 is passed through at least two pre-contact beds, where the gas is cooled between the beds at a temperature of not more than 550 ° C, and that after an intermediate absorption, the gas having an SO2 content of not more than 13% by volume is introduced as a second gas mixture in the subsequent oxidation step. The process according to claim 5 or 6, characterized in that in the subsequent oxidation step a catalyst is used, whose active component is based on vanadium for at least 5% by weight.
MXPA/A/2000/005564A 1998-01-13 2000-06-06 Catalyst for oxidizing so2 MXPA00005564A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19800800.7 1998-01-13

Publications (1)

Publication Number Publication Date
MXPA00005564A true MXPA00005564A (en) 2001-11-21

Family

ID=

Similar Documents

Publication Publication Date Title
US5286697A (en) Catalyst for the selective oxidation of sulphur compounds to elemental sulphur, process for preparing such a catalyst and method for the selective oxidation of sulphur compounds to elemental sulphur
CA2043539C (en) Monolithic catalysts for conversion of sulfur dioxide to sulfur trioxide
DK167850B1 (en) APPLICATION OF CYANINE INGREDIENTS FOR THE PREPARATION OF A DIAGNOSTIC AGENT
US4499197A (en) Co-gel catalyst manufacture
US4552746A (en) Process for the reduction of the sulfur content in a gaseous stream
US4818740A (en) Catalyst for the selective oxidation of sulfur containing compounds to elemental sulfur
JPS62297202A (en) Method of recovering sulfur from gas containing sulfur
US6500402B1 (en) Catalyst for oxidizing SO2 to SO3 and utilization of the catalyst in a method for producing sulfuric acid
EP0649337B1 (en) Desulphurisation of waste gases
CA1037224A (en) Process for absorbing so3
CN110300624A (en) Cupric MOZ zeolite for selective N Ox reduction catalysts
EP0715602B1 (en) Catalyst for the selective oxidation of sulfur compounds to elemental sulfur, process for preparing such catalyst and process for the selective oxidation of sulfur compounds to elemental sulfur
MXPA00005564A (en) Catalyst for oxidizing so2
AU2001256312B2 (en) Method for the catalytic conversion of gases with a high sulfur dioxide content
JPH0515784A (en) Regeneration of catalyst
EP0514941B1 (en) Process for the separation of sulphur oxides from offgases
CA2122321A1 (en) Process for purifying combustion plant flue gases which contain oxides of nitrogen and sulphur
US3454360A (en) Process for sulfuric acid manufacture
SU1616688A1 (en) Catalyst for conversion
CA1179826A (en) Oxidation of so.sub.2 and h.sub.2so.sub.4 manufacture
EP0479354B1 (en) Nitrided silica
US3880985A (en) Process for production of sulphur trioxide
US1852782A (en) Purification of sublimable organic materials
JPS61234945A (en) Regenerating method for catalyst
Nowińska Changes in Chemical Composition of a Vanadium Catalyst During the Reaction of SO2 Oxidation