AU639926B2 - Aluminium oxide tubes and process for manufacturing them - Google Patents

Aluminium oxide tubes and process for manufacturing them Download PDF

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Publication number
AU639926B2
AU639926B2 AU55657/90A AU5565790A AU639926B2 AU 639926 B2 AU639926 B2 AU 639926B2 AU 55657/90 A AU55657/90 A AU 55657/90A AU 5565790 A AU5565790 A AU 5565790A AU 639926 B2 AU639926 B2 AU 639926B2
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AU
Australia
Prior art keywords
pipe
green body
deformations
alumina
ceramic
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
AU55657/90A
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AU5565790A (en
Inventor
Gunter Adash
Gunter Frankfurter
Reinhard Manner
Ulf Plocker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ceramtec GmbH
Evonik Operations GmbH
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Ceramtec GmbH
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Filing date
Publication date
Application filed by Ceramtec GmbH filed Critical Ceramtec GmbH
Publication of AU5565790A publication Critical patent/AU5565790A/en
Application granted granted Critical
Publication of AU639926B2 publication Critical patent/AU639926B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B21/00—Methods or machines specially adapted for the production of tubular articles
    • B28B21/92—Methods or apparatus for treating or reshaping
    • B28B21/98—Methods or apparatus for treating or reshaping for reshaping, e.g. by means of reshape moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/40—Static mixers
    • B01F25/42—Static mixers in which the mixing is affected by moving the components jointly in changing directions, e.g. in tubes provided with baffles or obstructions
    • B01F25/43—Mixing tubes, e.g. wherein the material is moved in a radial or partly reversed direction
    • B01F25/433—Mixing tubes wherein the shape of the tube influences the mixing, e.g. mixing tubes with varying cross-section or provided with inwardly extending profiles
    • B01F25/4338—Mixers with a succession of converging-diverging cross-sections, i.e. undulating cross-section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J12/00—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor
    • B01J12/007—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor in the presence of catalytically active bodies, e.g. porous plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/0053—Details of the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/24—Stationary reactors without moving elements inside
    • B01J19/2415—Tubular reactors
    • B01J19/2425—Tubular reactors in parallel
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C3/00—Cyanogen; Compounds thereof
    • C01C3/02—Preparation, separation or purification of hydrogen cyanide
    • C01C3/0208—Preparation in gaseous phase
    • C01C3/0229—Preparation in gaseous phase from hydrocarbons and ammonia in the absence of oxygen, e.g. HMA-process

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Manufacturing & Machinery (AREA)
  • Catalysts (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Rigid Pipes And Flexible Pipes (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)

Description

-7 OPI DATE 29/11/90 AOJP DATE 10/01/91 APPLN. ID 55657 PCT NUMBER PCT/FP90/nn79 PcT INTERNATIONALE ANMELD'UNG VEROFFENTLICHT NACH DEM VERTRAG UI3LR vIE INTERNATIONALE ZUSAMMENARBEIT AUF DEM GEBIET DES PAT[ENTWESENS (PCT) (51) Internationale Patentklassiikation 5 11I) Internationale Ver6ffentlichungsnummer: WO 90/13405 B28B 21/98 Al (43) Internationalcs Ver~ffentlichungsdatum: 15. November 1990 (15.11.90) (21) Internationales Aktenzeichen: PCT/EP90/00723 (74) AnAwalt: SPI ESS, Bernhard; Hoechst Aktiengesellschaft Zentrale Patentabteilung, Postfach 80 03 20. D-6236 (22) Internationales Anmeldedatumn: 5. Mai 1990 (05.05.90) Frankfurt am Main 80 (DE).
Prioritfitsdaten: (81) Bestimmungsstaaten: AT (europdiisches Patent), AU, BE P 39 15428.9 11. Mai 1989 (11.05.89) DE (europ~isches Patent), BR, CH (europdisches Patent), DE (europiiisches Patent), DK (europ~isches Patent), ES (71) Anmelder (fi r alle Bestiinmungssaten ausser BR US): HO- (europitisches Patent), FR (europiiisches Patent). GB ECHST CERAMTEC AKTIENGESELLSCHAFT (europiiisches Patent), IT (europ~isches Patent). J P, LUI [DE/DE]; Wilhelmstrage 14, D-8672 Seib (europaisches Pater:), NL (europiiisches Patent). SE (europiiisches Patent), US.
(71) Anmelder (ffir alle Besinimungssmten ausser US): DEG US- SA AKTIENGESELLSCHAFT [DE/DE]; Postfach I I Verblff~ntlicht 33, D-6000 Frankfurt am Main Mit internarionalem Recherchenbericlu.
Vor Ablauf der fflr 4nderungen der AnsprIifCbe :ugclasse- (72) Erfinder; und nen Frist. Ver~ffentliclrung wird wiederhohl falls Anderun- Erfinder/Anmelder (nur fir US) ADASH, Gunter [DE/ gen eintreffen.
DE]; Amundsenstrage 13, D-8590 Marktredwitz (DE).
FRANKFURTER, GOnter [DE/DE]; Suttnerweg 4, D- 8590 Markredwitz MANNER, Reinhard [DE/ DEl; Bohnoefferstrafle 17, D-6457 Maintal-Dtirnigheim PLOCKER, Ulf [DE/DE]; Friedlandstrage 24, D-9 6454 Bruchk6bel 692 (54)Title: ALUMINIUM OXIDE TUBES AND PROCESS FOR MANUFACTURING THEM (54) IBezeichnung: ALUMINIUMOXIDROHRE UND VERFARREN ZU IHRER HERSTELLUNG Abstract 2j In a process for manufacturing gas-tight aluminium tubes suitable for carry--_ ing out catalytic high-temperature reactions, powdered aluminium oxide is mixed with water, a binder and a plasticizer, and the mixture is deformed by drawing a hank into a cylindrical green body, which is then deformed in at least two places so that the circular cross-section of the tube becomes approximately ellipsoidal. The deformed green body is dried arnd sintered at 1740'C. Excellent mixing of the gas in the tube is achieved as a result of the constrictions in the cross-section.
(57) Zusammenfassung Beschrieben wird emn Verfahren zur Herstellung cines gasdichten Aluminiumoxidrohres, das zur Durchf0hrung katalytischer Hochtemperaturr..,tionen geeignet 3 ist. Dabei wird Aluminiumoxidpulvdr mit Wasser und einem Bindeinittel und Plasti- I fiziermittel versetzt, das Gemisch durch Strangziehen zu einein zylindrischen GrOnk~rper verformt, und dieser Grdnk6rper an mindestens zwei Stellen so verforint, dag der ehemals runde Querschnitt des Rohres etwa die Form einer Ellipse annimmt.
Der verforinte Grflnki~rper wird getrocknet und bei 1740'C durchgesintert. Durch die Querschnittsverengungen wird eine besonders gute Durchmischung der Gase imA I4 4- I11 Till p HOECHST CERAMTEC AKTIENGESELLSCHAFT HOE 89/C004 Dr.JA/rk Description Alumina pipes and process for their production The present invention relates to gastight pipes of alumina ceramics. Gastight ceramic pipes are used for the catalytic conversion of a mixture of methane and ammonia into hydrocyanic acid and hydrogen at high temperatures in the BMA process Chemie-Technik 1978, page 231).
The reaction takes place over a platinum catalyst which is applied to the inside of an alumina pipe. The pipes are suspended inside a combustion chamber and are kept at about 1250 0
C.
The pipes used should be gastight and resistant to high temperatures. Furthermore, they should be capable of accepting the required amount of platinum per unit area on the inside. Coating of an alumina catalyst pipe with a platinum solution is described in Example 1 of German Patent 3,034,957. The production of alumina pipes which can be used for the BMA process and which are assigned to material classes KER 708 and KER 710 according to DIN 40,685 has long been part of the prior art. A pzocess for the production of coated A1 2 0, pipes having a very rough inside was proposed in German Patent 3,734,914.
ceramic pipes which, as a result of an altered geometry, lead to an improvement in the yield of the reaction in the BMA process.
The invention is based on the knowledge that, in the BMA Sprocess, improved mixing of the reaction gases is evident from the higher yields in the reaction. This is probably i due to a disturbance of the laminar flow in the catalyst pipe.
0I 2- A process for the production of a gastight alumina pipe which is suitable for carrying out catalytic high temperature reactions has now been found, water, a binder and a plasticizer being added to alumina powder, the mixture being extruded to give a cylindrical green body, the cylindrical pipe being sintered thoroughly at about 1740C and if necessary the sintered pipe being impregnated with a solution which contains the catalytically active metal ions, with the proviso that, based on the longitudinal direction, the cylindrical green body is deformed at two or more points following extrusion, in such a way that the formerly circular cross-section of the pipe assumes approximately the shape of an ellipse.
Figure 1 shows a longitudinal section of the pipe It can be seen that the wall of the pipe has been pressed in at a plurality of points. The diameter of the cylindrical pipe is constricted to the small elliptical diameter At right angles to this, the pipe is simultaneously expanded to the large elliptical diameter.
The degree of turbulence of the gas flowing through the pipe increases with increasing number of cross-sectional changes, ie. the number of deformations effected from outside, so that for practical purposes the cross-section is constricted to the small elliptical diameter at to 50, preferably at 10 to 30, particularly preferably at to 25, points, based on a length of 1 in. Figure 2 shows a cylindrical part in cross-section, Figure 3 shows a section at the level of the deformation III-III and Figure 4 shows a section at the level IV-IV. Figures 3 and 4 show the deformation of the circular cross-section to give an ellipse The upper limit of the number of deformations of the ceramic pipe is determined only by economic considerations. Particularly good mixing of the gases in the pipe can be achieved if the elliptical cross-sectional constrictions are produced so that they are rotated through a 90* relative to one another (cf. Figure 1 and Figure The distance between two cross-sectional
U
1"1 -3constrictions should be 20 to 100 mm, preferably 35 to mm. The deformation of the cylindrical green body can be effected by means of two hemispherical punch ends which act against one another, are made of hard rubber, plastic or ceramic and have a radius of about 10 to mm, tailored to the desired distance. Advantageously, the punch is pressed under vibration diametrically onto the tubular green body, since the thixotropic ceramic material is more readily deformable. Deformation of the tubular green body is carried out in such a way that the i axial ratio of the elliptical cross-section of the fired Spipe is 1.5 to 3, preferably 1.75 to 2.5. The ratio of i the internal diameter of the fired pipe (at the undeformed points) to the distance between two deformations should preferably be 1 10 to 1 2, a ratio of 1 6 to S1 4 being particularly preferred.
The production of alumina pipes has been known for many Syears. Examples of the production of transparent alumina pipes appear in, for example, German Offenlegungsschrift 3,201,750, German Offenlegungsschrift 2,810,128, U.S.
i Patent 4,396,595 and European Application 134,277. Since transparency of the pipes is not important in the present case, inorganic dopants, such as magnesium and zirconium Soxide, can be dispensed with. To ensure high thermal stability of the pipe, the purity of the alumina used should be not less than 90%, preferably not less than The best results were obtained with a purity of about 99%. An advantageous, conventional production process for alumina pipes consists essentially of the following three process steps: a) By milling alumina, an aqueous suspension of the pulverulent alumina is obtained.F b) The aqueous suspension from stage a) is atomized, and water and plasticizer are added to the atomized particles obtained. The mixture is kneaded to a plastic mass and the latter is extruded to give a SI~r i 4 tubular green body.
c) These pipes are first dried at 50 0 C and then fired at about 1740 0
C.
The initial milling of alumina in step a) is most advantageously carried out for a time sufficient to enable gas impermeability to be achieved in the subsequent firing at 1740°. This is the case with mean particle diameters of less than 15 im, in particular from 2 to 5 im. The atomization in step b) is preferably carried out without the addition of a binder. Usually high molecular weight organic compounds, such as polyvinyl alcohol and/or methylcellulose, or water-soluble starch (dextrin) are used as plasticizers in step The pipes are usually molded by extrusion; however, pipes can also be obtained by isostatic pressing, but this is not usual, owing to the costs. Molding of the green body, which molding ;1 process is described in the invention, is carried out S* between process steps b) and c) and has been previously described. The invention is illustrated in more detail ii by the Example.
Example 99% pure alumina powder is comminuted in a tumbling mill by wet milling. The median particle diameter in this wet milling (d 50 value) is 3 im. For further processing to pipes, the Al20 3 powder suspension is spray-dried, kneaded with water and a plasticizer and molded in a vacuum extruder to give pipes. The pipes then have an external diameter of 25.7 mm, an internal diameter of 19.8 mm and a length of about 3000 mm. 'Immediately after extrusion, the pipe is processed in such a way that it has in total 34 successive deformations, each 58 mm long. The total deformation distance of 34 58 mm 1972 mm is positioned so that it is equal distances from the pipe ends, ie. is located in the middle. These deformations are produced by hemispherical punch ends which are made of hard rubber, plastic or ceramic and have a diameter of 7 about 30 mm. For this purpose, the punches are pressed against the pipe cross-section diametrically and with simultaneous vibration the vibration facilitates deformation in such a way that the formerly circular outer cross-section is deformed to give an elliptical cross-section having axial lengths of 19.8 and 29.2 mm.
These rl.eformations are 50 mm apart and displaced by 900 with respect to one another. The pipe is then dried in a known manner at 50 0 C and then fired at 1740 0 C. The resulting firing shrinkage is about 14%. If the pipe has been shortened at both ends to a length of 2100 mm, an embodiment according to the Figure is obtained.
After being coated, a pipe produced in this manner gives a markedly higher yield of hydrocyanic acid in the BMA process.
[4j i *1 d

Claims (11)

1. Gastight ceramic pipe made of alumina which is suitable for carrying out catalytic high temperature reactions, wherein the circular cross-section of the pipe has been elliptically deformed at two or more points along the longitudinal direction of the pipe and wherein the ratio of the internal diame- ter of the pipe to the distance between two deformations lies within the range of 1 :10 to 1 :2.
2. Ceramic pipe as claimed in claim 1, wherein the ratio of the internal diameter of the pipe to the distance between two deformations lies within the range of 1 6to 1 4.
3. Ceramic pipe as claimed in claim 1 or 2, wherein the distance between two deformations lies within the range from 20 to 100 mm.
S4. Ceramic pipe as claimed in claim 3, wherein the distance between two deformations lies within the range from 35 to 75 mm.
5. Ceramic pipe as claimed in claim 1, wherein the axial ratio of the ellipse is from 1.5 to 3.
6. Ceramic pipe as claimed in claim 5, wherein the axial ratio of the S:ellipse is from 1.75 to
7. Process for the production of ceramic pipe as claimed in claims 1 to 6 comprising the steps of: mixing alumina powder with water, with binder and with plasticizer; extruding the mixture to give a cylindrical green body; V.9 7 deforming the cylindrical green body by means of two hemispherical punch ends acting against one another in such a way that the cross- section of the pipe assumes the shape of an ellipse; sintering the deformed green body at temperatures of about 1740 °C; impregnating the inside of the sintered pipe with a solution containing platinum.
8. Process as claimed in claim 7, wherein adjacent deformations being displaced by 90 0 with respect to one another.
9. Process as claimed in claim 7, wherein the hemisphere of the punch ends has a radius of 10 to 20 mm.
Process as claimed in claim 7, wherein the deformation is effected with simultaneous vibration of the punch.
11. Method for the preparation of hydrocyanic acid from ammonia and methane by carrying out a catalytic high temperature reaction within a gas- S..tight high temperature reaction pipe as claimed in claims 1 through 6. DATED this 1st day of June, 1993. HOECHST CERAMTEC AKT and DEGUSSA AKTIENGESELLSCHAFT WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VIC 3122 AUSTRALIA I ,*o o|o w a^ t HOE 89/C 004 ABSTRACT OF THE DISCLOSURE Alumina pipes and process for their production A process for the production of a gastight alumina pipe which is suitable for carrying out catalytic high temp- erature reactions is described. In this process, water and a binder and plasticizer are added to alumina powder, the mixture is extruded to give a cylindrical green body, and this green body is deformed at two or more point [sic] in such a way that the formerly circular cross- section of the pipe assumes approximately the shape of an ellipse. The deformed green body is dried and is sintered at 17401C. As a result of the cross-sectional constrictions, particularly good mixing of the gases in the pipe is achieved. A'i
AU55657/90A 1989-05-11 1990-05-05 Aluminium oxide tubes and process for manufacturing them Ceased AU639926B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3915428A DE3915428A1 (en) 1989-05-11 1989-05-11 ALUMINUM OXIDE TUBES AND METHOD FOR THEIR PRODUCTION
DE3915428 1989-05-11

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AU5565790A AU5565790A (en) 1990-11-29
AU639926B2 true AU639926B2 (en) 1993-08-12

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AU55657/90A Ceased AU639926B2 (en) 1989-05-11 1990-05-05 Aluminium oxide tubes and process for manufacturing them

Country Status (7)

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EP (1) EP0471714B1 (en)
JP (1) JPH0626805B2 (en)
AU (1) AU639926B2 (en)
BR (1) BR9007360A (en)
DE (2) DE3915428A1 (en)
ES (1) ES2048490T3 (en)
WO (1) WO1990013405A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10441942B2 (en) 2013-10-11 2019-10-15 Evonik Degussa, GmbH Reaction tube and method for producing hydrogen cyanide
US11897781B2 (en) 2016-09-28 2024-02-13 Evonik Operations Gmbh Method for producing hydrogen cyanide

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4128202A1 (en) * 1991-08-26 1993-03-04 Hoechst Ceram Tec Ag Sintered alumina reaction tube - with internal spiral rib, esp. for high temp. hydrogen cyanide synthesis
DE4128201A1 (en) * 1991-08-26 1993-03-04 Hoechst Ceram Tec Ag Sintered alumina reaction tube - contg. spiral insert, esp. for high temp. hydrogen cyanide synthesis
DE10025356A1 (en) * 2000-05-23 2001-11-29 Gewerk Keramchemie Hard rubber coatings for corrosion protection
WO2014167506A1 (en) * 2013-04-10 2014-10-16 Council Of Scientific & Industrial Research Flow reactor with pinched pipe sections for mixing and heat transfer
EP2813286A1 (en) 2013-06-11 2014-12-17 Evonik Industries AG Reaction tube and method for the production of hydrogen cyanide

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0097750A2 (en) * 1982-06-30 1984-01-11 COMMISSARIAT A L'ENERGIE ATOMIQUE Etablissement de Caractère Scientifique Technique et Industriel Method and apparatus for forming impressions on ceramic tubes

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1150246A (en) * 1955-05-27 1958-01-09 Improvements in apparatus for manufacturing tubular bodies exhibiting constriction
FR1425435A (en) * 1964-12-07 1966-01-24 Rhone Poulenc Sa Variable orifice extrusion die
US3708253A (en) * 1970-09-01 1973-01-02 J Lemelson Extrusion apparatus
FR2503615B1 (en) * 1978-11-27 1985-10-11 Commissariat Energie Atomique METHOD FOR MANUFACTURING CERAMIC CYLINDRICAL TUBES HAVING LOCALIZED FOOTPRINTS AND DEVICE FOR CARRYING OUT SAID METHOD

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0097750A2 (en) * 1982-06-30 1984-01-11 COMMISSARIAT A L'ENERGIE ATOMIQUE Etablissement de Caractère Scientifique Technique et Industriel Method and apparatus for forming impressions on ceramic tubes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10441942B2 (en) 2013-10-11 2019-10-15 Evonik Degussa, GmbH Reaction tube and method for producing hydrogen cyanide
US11897781B2 (en) 2016-09-28 2024-02-13 Evonik Operations Gmbh Method for producing hydrogen cyanide

Also Published As

Publication number Publication date
ES2048490T3 (en) 1994-03-16
DE3915428A1 (en) 1990-11-15
JPH04505134A (en) 1992-09-10
JPH0626805B2 (en) 1994-04-13
AU5565790A (en) 1990-11-29
EP0471714A1 (en) 1992-02-26
BR9007360A (en) 1992-04-28
EP0471714B1 (en) 1993-12-15
WO1990013405A1 (en) 1990-11-15
DE59003906D1 (en) 1994-01-27

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