Title of Invention

"METHOD FOR THE PRODUCTION OF CATALYST FOR HYDROGENATION OF UNSATURATED HYDROCARBONS"

Abstract Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons containing catalytically active amounts of Pd and optionally Ag on a support, characterized by the fact that the support is impregnated with a solution of salts of Pd and optionally Ag, these salts are reduced by means of a reducing agent , whereupon the support so impregnated is washed, dried and calcined and, if reduction is not complete, the still present oxides of Pd and Ag are reduced to the corresponding metals in a hydrogen-containing atmosphere.
Full Text The invention relates to a method for the production of catalyst for hydrogenation of unsaturated hydrocarbons.
A method for catalytic hydrogenation of acetylenic compounds with 2 or 3 carbon atoms to the corresponding olefin compounds is known from EP-A-0686615, in which a support catalyst in the form of spheres or extrudate is used, containing palladium and silver. At least 80% of the palladium and at least 80% of the silver are close to the periphery of the catalyst. The catalyst preferably contains aluminium oxide as support and 0.01 to 0.5 wt% palladium and 0.001 to 0.002 wt% silver. Because of the form of the support, the activity and selectivity, referred to weight, are relatively low. Only a relatively low space velocity can be used and the pressure losses in the catalyst then are relatively high.
A catalyst, containing Pd and Ag for selective hydrogenation of acetylene, is known from EP-A-9689872 . The catalyst is produced by treating a support material (preferably aluminium oxide).
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in the form of spheres or cylindrical pellets, with an alkaline solution of reducing agent for Pd
and Ag.
A supported catalyst for diolefin hydrogenation, containing palladium, silver and an alkali fluoride is known from IEP-A-0 693 315. Spherical pellets or cylindrical extrudates are preferably used as support.
A catalyst for hydrogenation of C2 to C10 alkynes. preferably acetylene, to the corresponding alkenes in the presence of sulfur compounds is known from FiP-A-0 738 540. which contains palladium, silver, at least one chemically bonded alkali metal (preferably K). chemically bonded fluorine and an inorganic support (preferably aluminum oxide) in the form of pellets.
IEP-A-0 732 M6 describes catalysts, whose supports represent molded articles with a trilobal cross section and through openings. The catalysts contain iron oxide-molybdium oxide compounds as catalytically active components. The catalysts arc used specifically for oxidation of methanol to formaldehyde, although some other applications not demonstrated by examples are stated (for example, hydrogenation of acetylene and olefins).
EP-A-464 633 describes catalysts, whose support represents molded articles with trilobal cross section and continuous openings (cf. Figure 5). The catalysts contain a mixture of elements of groups VIII and IB of the Periodic System, especially palladium and gold, as catalysis of the active component. They are used for conversion of olefins with organic carboxylic acids and oxygen to unsaturatcd esters, especially for production of vinyl acetate from ethylene and acetic acid.
EP-B-591 572 describes a catalytic material in the form of particles with a trilobal cross section and at least three continuous pore openings, as well as a specific ratio between height of the particles and spacing between the axes of the holes. This material is used for oxidativc dehydrogenation of methanol to produce formaldehyde.

Catalysts for selective hydrogenation of diolefins and alkynes to tnono-olefins and alkenes are also marketed by the applicant under the names G-58 and G-83, which contain palladium and silver on a spherical support or on a support in the form of solid pellets or extrudate (cf.data sheets " Girdler Catalysts G-58 C, G-58 D, G-58 H, G-58 I and G-83 for Selective Hydrogenation ", from January 1998).
Catalysts on such supports generally have the drawback that their activities and selectivities are relatively low and hydrogenation can only be run at relatively low space velocities. These catalysts also have relatively high flow resistance.
The task underlying the present invention was to eliminate these shortcomings. It was surprisingly found that these shortcomings could be eliminated by using a catalyst whose support has a specific shape.
The object of the invention is therefore a catalyst for hydrogenation of unsaturated hydrocarbons, containing catalytic reactive amounts of Pd and optionally Ag on a support; the catalyst is characterized by the fact that the support represents a molded article with a trilobal cross section, in which the lobes are provided with through openings.
The catalyst according to the invention ordinarily has a
geometric surface (GS) of about 0.2 to 3 sq cm, preferably about
0.7 to 1.9 sq cm, especially about 0.9 to 1.5 sq cm per molded
article.
The ratio between length(1) and diameter(d) of the trilobal
molded article is preferably as follows :
R1 = 1/d = 2-4
The ratio between geometric surface of a molded article and volume of the sold fraction of a molded article (Vf ) preferably is :
R2 = GO/Vf = 0.5-20 {mm"1), especially 1.4-4 (mm-1)
GO = GS;

Pd is preferably present in amounts of about 0.01 to J.5 wt% and Ag in amounts of about 0.1 to 0 5 wt.%, referred to the support material, and the weight ratio between Pd and Ag is about 0.1 to 5.0
The penetration depth of the catalytically active components (Pd and optionally Ag) into the support-molded articles after reduction is preferably about 60 to 300 m. referred to 80% of the active components.
The crystallite size of the Pd crystallites after reduction is about 2 10 15 nm. referred to 80% of the Pd crystallite, and the ratio between BET surface and size of the Pd crystallites (dpd) is preferably as follows:

R3 -r BIDT-O/Vifri = 0, ] - 1 0
The size of the Pd crystallites is determined according 10 the CO adsorption method according to the literalure source Journal of Catalysis 25. 148-160 (1972).
Aluminum oxide, especially 6-aluminum oxide, is preferably used as support. This is generally not present in pure form, but can also contain other aluminum oxide modifications. like a-aluminum oxide. Titanium dioxide, zirconium dioxide, silicon dioxide, zinc oxide, silicon carbide or talc, however, can also be used
The BET surface of the support is about 1 to 300 m2/g. preferably about 10 to 300 m2g, especially about 30 to 80 nr/g. The BET surface is determined according to the one-point method by nitrogen adsorption according to DIN 66132.
About 40% of the BET surface is situated in pores with a diameter of about 1570 to 80 nm and about 60% is situated in pores with a diameter of about 80 to 14 nm. Pore volume and distribution of specific surfaces to specific pore sizes is determined according to DIN 66133 (Hg porosimetry).
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The size of the Pd crystallites is determined according to the CO adsorption method according to the literature source Journal of Catalysis 25. 148-160 (1972).
Aluminum oxide, especially 6-aluminum oxide, is preferably used as support. This is generally not present in pure form, but can alsoconmin other aluminum oxide modifications. like a-nluminum oxide. Titanium dioxide, zirconium dioxide, silicon dioxide, zinc oxide, silicon carbide or talc, however, can also be used
The BET surface of the support is about 1 to 300 m'/g. preferably about 10 to 300 rn'g, especially aboul 30 to 80 nr/g. The BI:T surface is determined according to ihe one-point method by nitrogen adsorption according lo DIN 66132.
Aboul 40% of the BET surface is situated in pores with a.dtameter of about 1570 to 80 nm and aboul 60% is situated in pores with a diameter of about 80 to 14 nm. Pore volume and distribution of specific surfaces to specific pore sizes js determined according to DIN 66133 (Hg porosimeiry).

The trilobal molded articles used as support according to the invention are explained with reference to the accompanying drawing.
In the figure, (d) denotes the diameter, (I) the length of the trilobal molded article dl denotes the diameter of one lobe and d2 the diameter of the opening in a lobe.
The diameter (d) of the trilobal molded article preferably about 3 10 10 mm. the length (1) about 3 10 15 mm. and the diameter of an opening in a lobe (d2) about 0.5 to 5 mm.
The catalysts according to the invention preferably also contain limited amounts of alkali and/or alkaline earth metals, especially about 0.01 to 0.1 wt.% (calculated as oxides)
Relative to known catalysts, the catalysis according to the invention are- characterized by high activity and selectivity. 'Higher space velocities of about 12000 to 15000 can also be used (volume parts of reactions in the caseous state per volume pan of catalyst and hour = GSM V). compared with a space velocity of only about 3000 to 8000 during use of spheres, solid pellets or extrudntes The catalysts according to the invention also exhibit lower pressure losses (up to 60% relative to spherical of peller-hke supports (115 and 100%))
An object of the invention is also a method for production of the catalysts just defined, in which the support is impregnated with a solution of salts of Pd and optionally Ag (PdCl2. H2PdCl4 and AgNQ3) and the salts reduced with a reducing agent (e.g., sodium formate NaBH4, hydrazinc, formaldehyde, ascorbic acid, citric acid, Na acetate, oxalic acid, etc.). and preferably in an . alkaline medium at temperatures between about 20 and 100°C,preferably in the range from 40 to 60°C.
The reduction is preferably run in an aqueous-alkaline solution. In I his variant of the method, the Pd and optionally Ag oxide is fixed on the surface of the support and reduced there to the corresponding metals. In this manner, the penetration depth of the metal can be reduced to about 60 to 300 m

As an alternative, reduction can be run with a reducing agent in a nonaqueous solvent, if the reducing agent is broken down by water. This is especially true for NaBH.: and other hydrides or double-hydride, like LiAlH,. UBH.,. CaH: 01 l.all(.
The impregnated support is generally waMicd. dried and calcined- If reducuon :s not complete and Pd and Ay. are still present partially in ihc form of their oxides, these are. reduced to the corresponding metals by heating in a hydrogen-containing atmosphere (forming). Forming however, can also occur in the reactor, in which case only bydiogen K iuiiially iniroduced before introduction ni ihe compounds being hydrogenated.
The molded articles are generally produced by mixing the support material with water, a hinder (like carboxymethylccllulose) and/or a lubricant (for example, an alkaline earth or aluminum stearalcV
Production of the molded articles occurs in a pellet press with a rotary plate, on w hose periphery several openings wiih trilobal cross section are arranged. The mixture i* filled into these openings (matrices) and held from the bottom by a ram. through which three pins that lie at the sites of the openings to be produced are pushed upward during rotation of the rotary plate. On further rotation of the rotary plate, a ram with a trilobal cross section engages from the top. winch is provided with openings, into which the pins in the lower ram penetrate during pressing down of the upper ram. The pressed molded articles, during further rotation of the rotary plate, arc forced out of the matrices after retraction of the lower ram and further advance of the upper ram. The "green" molded articles are dried and calcined. Pores with the desired si/.e are formed in the molded articles.
The molded articles are then impregnated with a solution of salts of palladium and optionally silver, in which an alkaline solution is added after impregnation, in order to precipitate palladium and silver in (he form of the corresponding oxide. The solution or reducing ageni is men aooeo which reduces ihe oxides to the corresponding metal. However, it is also possible to use an alkaline reducing agent solution.

After precipitation of the oxides or metals of the catalytically active component(s), the molded articles arc washed, in order to eliminate soluble salts (for example. NaCI and NaNO3). The molded articles arc then dried and calcined, whereupon any still present oxides of the catalytically active components') arc reduced to ihe corresponding metals. Reduction generally occurs in a hydrogen atmosphere at temperatures from about 20 to 450°C Reduction can also occur in a reactor, in which case hydrogen or a hydrogen-containing gas is introduced before introduction of the compounds being hydrogenatcd.
Finally, an object of the invention is use of the aforementioned catalysis for hydrogenation of unsaturalcd hydrocarbons, especially for selective hydrogenauon of diolefins lo mono-olcfins or acetylenes to olefins.
The invention is explained b> the following examples:
Example 1
1000 parts by weight boehmite is mixed with 10 pans by weight water and 40 parts by weight magnesium stearatc to a homogeneous, pressable mass. This mass is introduced to the openings of a rotary plate of the pellet press just described, whose cross sections correspond to the depicted shape (d = 6 mm, dl = 4 mm. D2 = 1.5 mm. 1 = 6 mm). The molded articles are then pressed, as described above, and ejected from the pellet press. The obtained molded articles are dried for two hours al 120°C and calcined for 4.5 hours at 1075cC, in which the boehmite is largely converted to 9-aluminnm oxide (in addition io some a-aluminum oxide). The geometric surface is 1.3 cm' per molded article. The BF.T surface is then determined according to DIN 66132 at 30 m7g. The pore volume is then determined according to DIN 66133 at 0.35 mL/g. as well as the pore distribution. 40% of the BF.T surface pertains to pores with a diameter from 1750 io R0 nm. 60% of the BET surface pertains to pores with a diameter from 80 to 14 nm.
An H?PdCld solution (0.345 pans by weight palladium) in ) 150 parts by weight distilled water is rapidly added to 1000 pans by weight of the molded articles and slowly mixed for 5 minutes. The mixture is allowed io stand for about 60 minutes and ihe decolored solution then drained off.
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The moist product is immediately mixed with roughly 40oC warm 5% sodium formate solution and allowed to stand for 2.5 hours. The formate solution is then expelled and the product washed chloride-free with distilled water. The product is then calcined at 540°C for two hours.
1000 parts by weight" of the calcined product is added to a solution of 3.13 parts by weight AgNO3 in 1150 parts by weight distilled water and mixed slowly for 5 minutes. The mixture is allowed to stand for two hours and the solution then discharged. The product is calcined for 2.5 hours at 540°C.
The molded articles so obtained are filled into a tubular reactor that is initially scavenged with nitrogen. Hydrogen, at a temperature of 400°C, is then passed through for 8 hours, so that the palladium and silver on the molded articles are fully reduced. A mixture of 1.1 vol.% acetylene and 1.5 vol.% hydrogen in ethylene at a temperature of 50°C, a pressure of 2.5 MPa and a space velocity of 14000 liters of mixture per kg of catalyst per hour is then passed through the reactor. The acetylene is 54% converted to ethylene with a selectivity of 93%.
Comparative Example 1
A spherical catalyst support from 0-Al2O3 with a diameter of 2 to 4 mm, a geometric surface of 0.3 cm , a BET surface of 30 mg7g. a pore volume of 0.39 mL/g and a pore volume distribution of 40% between 1750 and 80 nm and 60% between 80 and 14 nm is impregnated with the H2PdCl4/AgNo3 solution of example 1 and reduced, dried, calcined and formed in the same manner as described in example 1. The catalyst is used for selective hydrogenation of acetylene to ethylene as in example 1, in which the same process conditions are employed. The acetylene is 50% converted to ethylene with a selectivity of 65% at a space velocity of 8000 (liter of reactants per liter of catalyst per hour).

Comparative Example 2
The working method of comparative example 1 was repealed with the deviation that a catalyst in the form of 4 x 4 mm pellets was used, all other conditions remaining unchanged. The. acetylene was 48% convened to ethylene with a sclectivity of 76%.
The catalyst according to example 1 and according to comparative examples 1 and 2 were measured in a separate pressure Joss tube (with nitrogen as measurement gas), the following pressure loss relation being determined: example 1: 60%. comparative example 1: 1 15%; comparative example 2: 100%.
Example 2
The working method of example 1 was repeated with the deviation that the support was calcined for 4.5 hours at 1020°C and the support so treated coated with 0.3 wt.% palladium. The catalyst had a BET surface of 70 + 5 cm2/g, a pore volume of 0.4 mL/g with 4.71% of the surface in pores with a diameter of 1750 to 80 nm and 76% in pores with a diameter of 80 to 14 nm. The rest of the surface pertained to pores with a diameter of The catalyst-molded articles were formed according to example 1 in a tubular reactor for 8 hours at 400°C and exposed to a mixture of hydrogen and a diene-containing pyrolysis gasoline (2 mol H2. 1 mol diene) first at 30°C and then at 60°C, a pressure of 3.0 MPa and a space velocity of 8 volume parts liquid pyrolysis gasoline per volume part catalyst and hour (LHSV). The composition.of the pyrolysis gasoline before selective hydrogenation is shown in Table 1.

Table 1
MOL%
Benzene 38.6
Toluene 22.6
o-xylene 1.7
p-xylene 4.1
in-xy]ene 2.0
ethylbenzene 2.0
styrene 6.0
cyclohexane 0.7
methylcylcohexane ] .5
hexadiene 1.2
cyclohexadiene 0.3
hexane 10.2
heptane 1.4
heptene 8.9
The styrene and diene conversions, as well as the diene selectivity after selective dehydrogenation are shown in Table II.
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Table \

Comparative Example 2
The working method of example 2 was repeated with the deviation that a catalyst in the form of spheres with a diameter of 2 10 4 mm with a palladium coaling of 0.3%, a geometric surface of 0.3 cm2. a BET surface of 70 + 5 cm2/g. a pore volume of 0.5 ml/g and a pore distribution as the catalyst of example 2 were exposed 10 pyrolysis gasoline with the composition staled in Table 1 at an initial temperature of 30°C and later 60°C a pressure of 3.0 MPa and an l.SHV of 4. The styrene and diene conversions, as well as the diene selectivity after selective hydrogeation, are shown in Table III.
Table III

According to the working method of example I of EP-0 314 O24-A1. a commercial titanium dioxide (P-25 Dcgussa) is homogenized in an intensive mixer with addition of about 55 wt.% water and M wt.9r isopropy] titanate for 45 minutes. After several hours of drying at 1 10cC, the TiO? mass is subjected to size reduction, mixed with aluminum stearate as pelletizing agent and pressed into molded articles with a trilobal cross section according to example I (dimensions as in example I).

The TIO2 molded articles are calcined for 3 hours at 550°C in an oxidizing atmosphere.
The geometric surface of the support was 1.3 cm2 per molded article, the BET surface 36 m /g, the pore volume 0.39 mL/g, 3.7% of the BET surface pertained to pores with a diameter from 1750 to 80 nm. 95.8% pores with a diameter of 80 to 14 nm.
The TiO2 support was spray-impregnated with an 8% aqueous sodium formate solution (30 mL formate solution per 100 g support). The support so pretreated was then spray-impregnated with the same volume with a 2.5% aqueous PdCl2 solution. The support molded articles were coated with formate solution: filtered by suction and washed chloride-free for complete reduction of the mobile metal. After drying at 100°C. they were calcined for 6 hours to a final temperature of 400°C. Promotion with silver was then carried out. For this purpose, the palladium-containing TiO2 molded articles were impregnated at room temperature with silver nitration solution, dried at 110°C and calcined for another 6 hours to a temperature of 360°C. The palladium content was 0.21 wt.%, the silver content 0.12 wt.%.
The catalyst was used at a pressure of 0.15 MPa: a temperature of 120°C and a LHSV of 15 h-1, with a molar ratio H2/diene of 2:1 for selective hydrogenation of a liquid diene-containing mixture with the composition
- 85.7 mol% paraffin
-11.1 mol% mono-olefin
- 0.85 mol% dienes
- 2.40 mol% aromatics.
Diene conversion was 80% at a selectivity of 85%.
Comparative Example 3
The working method of example 3 is repeated, with the deviation that solid pellets, with dimensions of 4.5 x 4.5, were used instead of the trilobal molded articles, and they were coaled
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in the same manner as in example 3 with the catalytically active metals. The support had a BET surface of 33 m2/g and a pore volume of 0.2 mL/g, 51% of the BET surface pertaining to pores with a diameter from 1750 to 80 nm, 87.3% of the pores with a diameter from 80 to 14 nm. The catalysts contained 0.213 wt.% Pd and 0.27 wt.% Ag.
The catalyst was used for selective hydrogenation of the diene-containing mixture used in example 3 (LHSV = 10H-1;T= 120°C, pressure = 0.15 MPa, molar ratio H2: diene = 4:1).
The diene conversion was 70% at a selectivity of 60%.
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We claim -
1 Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons
such as herein described, containing catalytically active amounts of Pd and optionally Ag on a support characterized by representing a molded material with a trilobal cross-section in which the lobes are provided with through opening, which comprises the steps of impregnating the support with a solution of salts of Pd such as herein described and optionally Ag, these salts are reduced by means of a reducing agent such as herein described, whereupon the support so impregnated is washed with a conventional liquid and, if reduction is not complete, the still present oxides of Pd and Ag are reduced by heating such as herein described, in a hydrogen-containing atmosphere to the corresponding metals
2. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons as claimed in claim 1, wherein the support represents a molded material with a trilobal cross section, in which the lobes are provided with through openings.
3 Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons as claimed in claim 1, wherein the ratio between length(l) and diameter(d) of the trilobal molded articles is as follows :

4. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons as claimed in claims 1 to 3, wherein the geometric surface(GS) is about 0 2 to 3 cm , preferably about 0 7 to 12 sq cm, especially about 0 9 to 1.5 sq cm per molded article.
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5. Method for the production of catalyst for hydrogenation of
unsaturated hydrocarbons as claimed in claims 1 to 4, wherein the
ratio between the geometric surface of a molded article and the
volume of the solid fraction of a molded article(Vf)

6. Method for the production of catalyst for hydrogenation of
unsaturated hydrocarbons as claimed in claims 1 to 5, wherein the
Pd is present in amounts of about 0.01 to l. 0 wt. % and Ag in
amounts of about 0.1 to 0.5 wt.%, referred to the support
materials, and that the weight ratio between Pd and Ag is about
0.1 to 5.0.'
7. Method for the production of catalyst for hydrogenation of
unsaturated hydrocarbons as claimed in Claims 1 to 6, wherein the
crystallite size of the Pd crystallites is about 2-15 nm after
reduction (referred to 80% of the Pd crystallites).
8. Method for the production of catalyst for hydrogenation of
unsaturated hydrocarbons as claimed in claims l to 7, wherein the
ratio between BET surface and size of the Pd crystallites(dpd) is
as follows :

9. Method for the production of catalyst for hydrogenation of
unsaturated hydrocarbons as claimed in claims I to 8, wherein the
support is aluminium oxide, especially 0-aluminium oxide.
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10. Method for the production of catalyst for hydrogenaration of thsaturated hydrocarbons
as claimed in claims 1 to 9, wherein the BET surface of the support is about 1 to 300 sq m/g,
preferably 10 to 300 sq m/g, especially 30 to 80 sq m/g
11. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons
as claimed in claims 1 to 10, wherein about 40% of the BET surface is found in pores with a
diameter of about 1750 to 80 nm about 60% in pores with a diameter of about 80 to 14 nm.
12. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons
as claimed in claims 1 to 11, wherein the diameter(d) of the trilobal molded article is about 3
to 10 mm, the length(l) about 3 to 15 mm and the diameter of an opening in a lobe(d2) about
0.5 to 5 mm.
13. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons
as claimed in claims 1 to 12, wherein the catalyst also contains limited amounts of alkali and/or
alkaline earth metals such as herein described, preferably about 0.01 to 0.1 wt% (calculated
as oxides).
14. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons
as claimed in claims 1 to 13, wherein the reduction is run in an alkaline medium such as herein
described, at temperatures between about 20 and 100 degree C, preferably in the range from
about 40 to 60 degree C.
15. Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons
as claimed in claims 1 to 14, wherein reduction is run in an aqueous-alkaline solution.


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Method for the production of catalyst for hydrogenation of unsaturated hydrocarbons containing catalytically active amounts of Pd and optionally Ag on a support, characterized by the fact that the support is impregnated with a solution of salts of Pd and optionally Ag, these salts are reduced by means of a reducing agent , whereupon the support so impregnated is washed, dried and calcined and, if reduction is not complete, the still present oxides of Pd and Ag are reduced to the corresponding metals in a hydrogen-containing atmosphere.

Documents:


Patent Number 208406
Indian Patent Application Number IN/PCT/2002/01037/KOL
PG Journal Number 30/2007
Publication Date 27-Jul-2007
Grant Date 26-Jul-2007
Date of Filing 09-Aug-2002
Name of Patentee SUD-CHEMIE AG
Applicant Address LENBACHPLATZ 6, D-80333 MUNCHEN,
Inventors:
# Inventor's Name Inventor's Address
1 PETROLLI, MAURO STADEMANNSTRASSES 7, D-81737 MUNCHEN,
2 GEYER, INGRID AM KRONENBERG 36, D-87600 KAUFBEUREN,
3 CASAGRANDE, FRANCESCO 28060 SAN NAZZARO, SESIA,
PCT International Classification Number B01J 35/02
PCT International Application Number PCT/EP 01/01365
PCT International Filing date 2001-02-08
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 100 05 775.6 2002-02-10 Germany
2 100 48 219.8 2000-09-28 Germany