PROCESS FOR PRODUCING TENSIDE-STABILIZED COLLOIDS OF MONO- AND BIMETALS OF THE GROUP VIII AND IB OF THE PERIODIC SYSTEM IN THE FORM OF PRECURSORS FOR CATALYSTS WHICH ARE ISOLABLE AND WATER SOLUBLE AT HIGH CONCENTRATION

Abstract: The invention relates to a process for producing tenside-stabilized colloids of mono- and bimetals of the group VIII and Ib of the periodic system which are isolable in the form of powder and which are soluble at a concentration of at least 100 mg atom of metal/l of water, from metal salts in the presence of strongly hydrophilic tensides with hydrotriorganoborates in THF, or with simple chemical reduction agents like hydrogen or alkali formate in water and alcohols, respectively. Furthermore, the subject matter of the invention is the use of the tenside-stabilized colloids which are produced according to this process as precursor for supported catalysts for the selective cis-hydrogenation of C-C triple bonds, for the selective hydrogenation of functional groups at the aromatic nucleus, for the selective hydrogenation of benzene to cyclohexene, for the partial oxidation of the primary alcohol functionality in carbohydrates, as well as for use as a precursor for electrocatalysts in fuel cells.

Description: Process for producing tenside-stabilized colloids of mono- and bimetals of the group VIII and lb of the periodic system in the form of precursors for catalysts which are isolable and water soluble at high concentration Summary The invention relates to a process for producing tenside- stabilized colloids of mono- and bimetals of the group VIII and lb of the periodic system which are isolable in the form of powder and which are soluble at a concentration of at least 100 mg atom of metal/1 of water, from metal salts in the presence of strongly hydrophilic tensides with hydrotriorganoborates in THF, or with simple chemical reduction agents like hydrogen or alkali formate in water and alcohols, respectively. Furthermore, the subject matter of the invention is the use of the tenside- stabilized colloids which are produced according to this process as precursor for supported catalysts for the selective cis- hydrogenation of C-C triple bonds, for the selective hydrogenation of functional groups at the aromatic nucleus, for the selective hydrogenation of benzene to cyclohexene, for the partial oxidation of the primary alcohol functionality in carbohydrates, as well as for use as a precursor for electrocatalysts in fuel cells. Description of the process The use of colloidally stabilized one- and multi-metallic nanoparticles as separately isolable precursor for producing supported metal catalysts is a new, economically beneficial alternative to the traditional in situ formulation of active CONFIRMATION COPT metal components on carrier surfaces (H. Bδnnemann et al., J. Mol. Catal. ϋJ> (1994), 129-177] . The particular characteristic of the process according to the invention is the pre-formation of colloidally stabilized metal nanoparticles, optionally having an intermetalic composition, with defined size and particle structure. The characteristics of the catalyst (activity, selectivity, lifetime) of such metal colloids which are fixed on carriers are superior to conventional, supported catalysts. The preferred solvent in this catalyst technology is water, due to economical and ecological reasons. The subject matter of the present invention is a process which permits to stabilize mono- and bimetallic nanoparticles in the form of powder in such a way, that highly concentrated colloidal solutions of the corresponding mono-and bimetallic catalyst-precursor can be produced in water without appreciable metal precipitations. By fixation of the precursor from aqueous solution on organic or inorganic carrier materials, new heterogeneous catalysts are prepared according the invention, for. e.g. selective hydrogenations, partial oxidations, or electrocatalysts for fuel cells. According to the state of the art, some nanometals can be stabilized colloidally in water [T. Sato, S. Kuroda, A. Takami, Y. Yonezawa, H. Hada, Appl . Organomet. Chem. 1991, 5, 261; T. Sato et al., J. Appl. Phys . 1990, 68,1297; T. Sato et al . , J. Chem. Soc, Faraday Trans. 1, 1987, 83,1559; T. Sato, S. Kuroda, A. Takami, Y. Yonezawa, H. Hada, Appl. Organomet. Chem. 1991, 5, 261; J. H. Fendler, "Membrane-Mimetic Approach to Advanced Materials", Springer-Verlag, Berlin, 1994; J. S. Bradley in "Clusters and Colloids", (Ed. G. Schmid) , VCH, Weinheim 1994; H. Hirai, Y. Nakao, N. " Toshi a, Chem. Lett. 1978, 5, 545; M. Ohtaki, M. Komiyama, H. Hirai, N. Toshima, Macro olecules 1991, 24, 5567; N. Toshima et al., J. Phys. Chem., 1991, 95, 7448; N. Toshima, T. Yonezawa, Makro ol . Chem., Macro ol . Symp. , 1992, - 3 - 59,327; N. Toshima et al., J. Phys. Chem. 1992, 96,9927; K. Torigoe, K. Esumi, Langmuir 1993, 9, 1664; J. S. Bradley et al., Chem. Mater. 1993, 5, 254; H. Hirai, Y. Nakao, N. Toshima, Chem. Lett. 1976, 9,905; M. Ohtaki, M. Komiyama, H. Hirai, N. Toshima, Macromolecules 1991, 24,5567, N.Toshima, M. Ohtaki, T. Teranishi, Reactive Polym. 1991, 15, 135; C. Larpent, F. Brisse-Le Menn, H. Patin, Mol. Catal. 1991, 65, L35; N. Toshima, T. Takahashi, Bull. Chem. Soc. Jpn. 1992, 65, 400-9]. However, the described metal colloids cannot be isolated, and they are soluble in water only at a high dilution. Therefore, they are not suitable as a catalyst precursor. Some authors could isolate water soluble nanometal colloids in the presence of hydrophilic P- and N-donators [J. S. Bradley in "Clusters-and Colloids", (Ed. G. Schmid) , VCH, Weinheim 1994; G. Schmidt, Chem. Rev. 1992, 92, 1709, H. Liu, N. Toshima, J. Chem. Soc, Chem. Commun. 1992,1095; C. Amberger, Ber. 1904, 37,124; C. Paal, C. Amberger, Ber. 1905, 38,1398]. Since P- and N-donators, being Lewis bases, give defined metal complex compounds with transition metals which, as is generally known, affects the catalytic efficiency of metals, the use of the mentioned complexing agent for the production of water soluble catalyst precursors is not suitable in the meaning of the present invention. Furthermore, the synthesis of these complexing agents occurs in several steps, and it is uneconomical. Suitable auxiliary agents are known for stabilizing nanometals in water. Referring to this, also surface-active agents (tensides) were proposed by some authors [H. G. Petrow and R. J. Allen (Prototech Company), US-C 4,044,193 (1977); G. V. Lisichkin, A. Ya. Yuffa and V. Yu. Khinchagashvii, Russ. J. Phys. Chem., 50 (1976) 1285; V. M. Deshpande, P. Singh and C. S. Narasimhan, J. Mol. Cat., 53 (1989) L21; V. M. Deshpande, P. Singh and C. S. Narasimhan, J. Mol. Cat., 63 (1990) L5; V. M. Deshpande, P. Singh and C. S. Narasimhan, J. Chem. Soc, Chem. Commun., 1990, 1181; Y. Nakao and K. Kaeriyama, J. Coll. and Surf. Sci., 110(1) (1986) 82; C. Larpent, F. Brisse-Le Menn und H. Patin, New J. Chem. 15 (1991) 361; K. Esumi, M. Shiratori, H. Ihshizuka, T. Tano, K. Torigoe and K. Meguro, Langmuir 7 (1991) 457; N. Toshima, T. Takahashi und H. Hirai, Chemistry Letters, 1985, 1245; N. Toshima and T. Takahashi, Chemistry Letters, 1988, 573; J. Kiwi and M. Gratzel, J. Am. Chem. Soc. 101 (1979), 7214] . However, the colloidal solutions of the corresponding metals in water are only stable at an extremely low concentration, not isolable and therefore, are discarded from the beginning as being used according to the invention as precursors for technical catalysts. A significant progress in the production of water soluble metal colloids received Reetz and Helbig [M.T. Reetz, W. Helbig, J.Am.Chem.Soc. 1994, 116, 7401] by use of a LiCl salt of the sulfobetaine 3- (dimethyldodecyl-ammonio) propane sulfonate in an electrochemical reduction process. According to this electro¬ chemical process, e.g., a good water soluble palladium colloid which is stabilized with sulfobetaine having a size of 8 nm, was isolated. An economical alternative to the electrochemical production of nanometals is the chemical reduction of metal salts [H. Bόnnemann et al.,Angew. Chem. Int. Ed. Engl. 29 (1990) , 273; H. Bόnnemann et al . , J. Mol. Catal. 8.6 (1994), 129-177] . The use of commercial tensides for the stabilization of chemically-reductively produced nanometal colloids in highly concentrated aqueous solution could not be learned from the state of the art and from the ruling doctrine. On the contrary, surface-active substances are considered as auxiliary agents for the precipitation of metals from aqueous solution. Surprisingly, it was found now that the chemical reduction of metal salts in the presence of extremely hydrophilic tensides leads to isolable nanometal colloids which form in an amount of at least 100 mg atom metal/1 long-term stable solutions in water. The advantage according to the invention of extremely water soluble tensides for the stabilization of colloids illustrates the following com¬ parison: Whereas the poor water soluble tenside C 16 H 33 Me 3 NBr (solubility according to Fluka catalogue 1993/94, CAS No. 57-09-0 = 0,1 mole/1 of water) does not allow a stabilization of metal colloids in water according to the state of the art [G.V. Lisichkin, A.Ya. Yuffa and V.Yu. Khinchagashvii, Russ. J. Phys. Chem., 50 (1076), 1285], the use according to the invention of 3- (dimethyldodecyl-ammonium)propane sulfonate (solubility according to Fluka catalogue 1993/94, CAS No. 14933-08-5 = 1,2 mole/1 of water) results in a solubility of the stable metal colloids of at least 100 mg atom/1 of water. Inorganic or organic salts of one or more metals from the groups VIII and lb of the periodic system are dissolved, respectively suspended, in water or in a strongly solvated organic solvent (ether, THF, alcohols) in the presence of an extremely hydrophilic tenside, and they are reacted between 0°C and 100°C at environmental pressure, optionally by addition of alkali carbonate, with chemical reduction agents. Such reduction agents are, e.g., hydrogen, alkali formate, complex hydrides and other materials which are technically available for the reduction. The selection of the reducing agent will be determined, respectively, according to the reducing capacity which is necessary for the respective metal salt, as well as according to the stability of the used reagents in protic/aprotic solvents. As the extremely hydrophilic tensides, according . to the invention, the following hydrophilic types of tensides can be used for the chemically-reductive preparation of colloids of mono- and bimetals of the groups VIII and lb of the periodic system in the form of isolable powders which are water soluble in high concentration (> 100 mg atom/1) : amphiphilic betaines (A) , cationic tensides (B) , fatty alcohol-polyglycolether (C) , polyoxyethylene-carbohydrate-fatty alkylester (D) , anionic tensides (E) and amphiphilic sugar tensides (F) . The metal colloids which are prepared according to the invention as catalyst-precursor can be raised from aqueous solution to organic or inorganic carrier materials (e.g. activated carbon, graphitized carbon black, metal oxides) for the production of technically advantageously mono- and bimetallic heterogeneous catalysts. These heterogeneous catalysts which are prepared according to the invention are suitable for the selective cis- hydrogenation of C-C triple bonds (mono- and bimetallic Pd- colloidal catalysts on A-carbon) , the selective hydrogenation of functional groups, as for instance -N0 2 , at the aromatic nucleus (e.g, mono- and bimetallic Pt-colloid on A-carbon), for the selective hydrogenation of benzene to cyclohexene (e.g., Ru- colloid on La 2 0 3 ) , for the partial oxidation of the primary alcohol functionality in carbohydrates (e.g., Pd-, Pt-, Pd/Pt- colloids on A-carbon) , or as electrocatalysts for fuel cells (e.g., Pt-colloid on graphitized carbon black). Examples The following types of tensides can be used according to the invention for the nanometal stabilization (table 1 ) . The examples illustrate the invention without being limited thereby . Table l Tenside-stabilized colloids of metals of the groups VIII and lb of the periodic system by reduction with alkali BEt 3 H in THF (see table 2) . Example 1 Ru-colloid (table 2, No. 4) 2.43 g (7.23 mmole) 3-(N,N-dimethyldodecylammonium)-propane sulfonate (tenside Al) are suspended under protective gas (argon) in 100 ml THF, and 5.60 ml of a 1,29 molar LiBEt 3 H solution in THF is added thereto at 20 C C, whereby a clear tenside-reduction agent-solution results. This clear tenside- reduction agent-solution is dropped within 4 h at 40°C under stirring to a suspension of 0.5 g (2.41 mmole) RuCl 3 in 100 ml THF, and stirring is continued for further 16 h at 20°C. A grey- black precipitate and an almost colorless, supernatant solution are formed. After 2 h of settling, the supernatant solution is siphoned off, 5 ml acetone and 100 ml THF are added. It is stirred for about 10 min, and again the precipitate is allowed to settle during 1 h. The supernatant clear solution is siphoned off, and the precipitate is dried in high vacuum (10 ~ mbar, 40°C, lh) . 0,65 g Ru-colloid in the form of a black solid having a Ru-content of 12.62% are obtained. Particle size according to TEM (transmission electron microscopy) : 1-2 nm. Physical characterization: The colloids from experiments No. 5 and 26, table 2, were characterized by means of UV spectroscopy. The XPS-spectrum of colloid No. 19, table 2 shows metallic platinum. The mean particle size was determined by means of TEM of the following colloids: No. 19: 2 nm; No. 20: 2,8 nm; No. 21: 3,7 nm (table 2) . Tenside-stabilized colloids of bimetals of the groups VIII and lb of the periodic system by reduction with alkali BEt 3 H in THF (see table 3) . Example 2 Pt-Co-colloid (table 3, No. 3) 2.62 g (7.8 mmole) 3-(N,N-dimethyldodecylammonium)-propane sulfonate (tenside Al) are suspended under protective gas (argon) in 100 ml THF, and 6 ml of a 1,29 molar LiBEt 3 H solution in THF is added thereto at 20°C, whereby a clear tenside- reduction agent-solution results. This clear tenside-reduction agent-solution is dropped within 20 h at 20°C under stirring to a suspension of 0.78 g (2.93 mmole) PtCl 2 and 0.13 g (0.98 mmole) CoCl 2 in 120 ml THF, and stirring is continued for further 67 h at 20°C. A dark grey-brown precipitate is formed. 10 ml acetone are added, it is stirred for 1 h, and the precipitate is allowed to settle. The supernatant clear solution is siphoned off, and the precipitate-is washed twice with 50 ml THF. After drying in high vacuum (10 mbar, 20°C, lh) 2,84 g Pt-Co-colloid in the form of a black solid having a metal content of 17.6% Pt and 1,5% Co is obtained. Particle size according to TEM: 2-6 nm. Physical characterization: The colloids from experiments No. 4 and 6, table 3, were characterized by means of UV spectroscopy. Tenside-stabilized colloids of metals of the groups VIII and lb of the periodic system by reduction with alkali metal boron hydrides in H 0 and alcohols, respectively (see table 4) . Example 3 Pt-colloid (table 4, No. 7) 2.7 g (5.3 mmole) H 2 PtCl 6 x 6 H 2 0 and 3.6 g (10.6 mmole) 3-(N,N- dimethyldodecylammonium)propane sulfonate (tenside Al) are dissolved under the protective gas argon in 100 ml H 2 0, and within 2 h a solution of 1.2- g (31.8 mmole) NaBH 4 in 50 ml Hn0 are added thereto at 20°C. The resultant deep-black reaction mixture is filtered over a D4 glass frit, and the deep-black clear solution is concentrated in high vacuum (10 mbar, 40°C) to dryness. 6.39 g Pt-colloid is yielded in the form of a black solid having a Pt content of 12,1%. Mean particle size according to TE : 4,6 nm. Physical characterization: The colloid from experiment No. 2 , table 3, was characterized by means of UV spectroscopy. Tenside-stabilized colloids of bimetals of the groups VIII and lb of the periodic system by reduction with alkali metal boron hydrides in H 2 0 and alcohols, respectively (see table 5) . Example 4 Pt-Cu-colloid (table 5, No. 1) 1.35 g (2.65 mmole) H 2 PtCl 6 x 6 H 2 0 and 0.11 g (0.66 mmole) CuCl 2 x H 2 0 are dissolved with 4.3 g (12.7 mmole) 3-(N,N- dimethyldodecylammonium)propane sulfonate (tenside Al) under protective gas (argon) in 100 ml H 2 0, and within 2 h a solution of 0.38 g (17.0 mmole) LiBH 4 in 50 ml ^ O are added thereto at 20°C. The resultant deep-black reaction mixture is filtered over a D4 glass frit, and the deep-black clear solution is concentrated in high vacuum (10 ~3 mbar, 40°C) to dryness. 7.05 g Pt-Cu-colloid is yielded in the form of a black solid having a metal content of 7.02% Pt and 0,52% Cu. Particle size according to TEM: 2.5-4.5 nm; EDX-analysis: Pt:Cu = 1:0.2 Physical characterization: The particle size of colloid no..6, table 5 was determined by TEM: 3-5 nm; EDX-analysis: Pt:Ru = 1:1.05 Tenside-stabilized colloids of metals of the groups VIII and lb of the periodic system by reduction with hydrogen in H 2 0 (see table 6) . Example 5 Pt-colloid (table 6, No. 15) 1.4 g (5.3 mmole) PtCl 2 , 7.2 g (21.2 mmole) 3-(N,N- dimethyldodecylammonium)propane sulfonate (tenside Al) and 0.4 g (5.3 mmole) Li 2 C0 3 are taken up under a protective gas (argon) in 100 ml H 2 0, and during 3 h a stream of H 2 is passed through this mixture at 20°C. A clear black solution is formed after approximately 30 min, from which all volatile matter is separated in high vacuum (10 mbar, 40 C C) . 8.4 g Pt-colloid is yielded in the form of a black solid having a Pt-content of 10.7%. Mean particle size according to TEM: 2.2 nm. Annotation relating to operating the reaction: Experiment no. 17, table 6 - deviating from the description of the above experiments - was performed in air. Physical characterization: The colloids from experiment nos. 1, 4, 5 and 6, table 6 were characterized by uv-spectroscopy. The mean particle size of the following colloids was determined by TEM: no. 10:2.2 nm; no. 11:3.1 nm (table 6). Tenside-stabilized colloids of bimetals of the groups VIII and lb of the periodic system by reduction with hydrogen in H 2 0 Example 6 Pt-Pd-colloid 1.35 g (2.65 mmole) H 2 PtCl 6 x 6 H 2 0 and 0,7 g (2.65 mmole) Pd(N0 3 ) 2 x H 2 0 are dissolved together with 7 g polyoxyethyenelau- rylether (tenside Cl) and 1.0 g (13.25 mmole) Li 2 C0 3 under a protective gas (argon) in 100 ml H 2 0, and during 4 h H 2 gas is passed through it at 20°C. The resultant deep black reaction mixture is filtered over a D4 glass frit, and the deep-black clear solution is concentrated in high vacuum (10 mbar, 40°C) to dryness. 11,2 g Pt-Pd colloid are obtained in the form of a black solid having a metal content of 4.3% Pt and 2.3% Pd. Tenside-stabilized colloids of bimetals of the groups VIII and lb of the periodic system by reduction with Li-formate in H 2 0 Example 7 Pt-Rh-colloid 1.35 g (2.65 mmole) H 2 PtCl 6 x 6 H 2 0 and 0,7 g (2.65 mmole) RhCl 3 x H 2 0 are dissolved with 7 g polyoxyethylene laurylether (tenside Cl) under a protective gas (argon) in 150 ml H 2 0, and during 20 h a solution of 2.86 g (55.0 mmole) Li-formate in 50 ml H 2 0 is added thereto at 60°C. The resultant deep black reaction mixture is filtered over a D4 glass frit, and the deep-black clear solution is concentrated in high vacuum (10 ~3 mbar, 40°C) to dryness. 12.5 g Pt-Rh colloid are obtained in the form of a black solid having a metal content of 4.0% Pt and 2.0% Rh. Fixation of the carrier Example 8 Preparation of a Pd-tenside Al/activated carbon catalyst for the partial oxidation of carbohydrates (5 percent per weight of Pd/C) 1.254 g of a icroporous (< 5nm) powdery active carbon having a grain size of 20 μm are suspended in 50 ml deoxygenated H 2 0, and 64.7 ml of a solution of Pd-colloid no. 16, table 2 in deoxygenated water (1.02 mg Pd/ml) are given thereto within 16 h under stirring. The covered active carbon is separated over a glas filter frit; yielding a colorless filtrate. It is washed twice with 25 ml deoxygenated water, respectively., and dried during 16 h in vacuum (10 mbar) . Subseguently, the catalyst is oxygenated during 16 h at 0,1 mbar (approximately 0,2% 0 2 ) . The obtained catalyst can be handled in air. Example 9 Preparation of a Pd-tenside Al/active carbon-catalyst for the selective hydrogenation of C≡C (5% per weight of Pd/C) A solution of 0.7885 g (corresponding to 0.1053 g Pd) colloid no. 16, table 2 in 40 ml distilled water is dropped within 16 h under argon to 2.00 activated carbon (Degussa carrier material 101, charge 514) which was given in the form of a suspension in 40 ml water under argon. Thereby, the colloid is completely absorbed on the activated carbon which can be seen by the decoloration of the solution. The catalyst is filtered off, dried during 16 h at 20°C in high vacuum (10 ~3 mbar) , and it is oxygenated during 16 h at 20°C at 0.1 mbar (approximately 0.2% 0 2 ). Example 10 Preparation of a Ru-tenside Al/lanthanumoxid catalyst for the selective hydrogenation of benzene (1 percent per weight of Ru/La 2 0 3 ) . 5.505 g La 2 0 3 (BET surface area of 59 m 2 /g) are suspended in 100 ml deoxygenated H 2 0 under a protective gas. Within 30 min 50 ml of a solution of Ru-colloid no.4, table 2 in deoxygenated H 2 0 (440 mg, EA: 12.62% Ru) , is dropped thereto. Thereby, the white oxidic carrier changes to a grey colour. The complete absorption can be seen from the decoloration of the black solution. The coated carrier is allowed to settle completely, and the supernatant, clear aqueous solution is siphoned off. After drying in vacuum (10 ~3 mbar, 3 h) , a grey powder is obtained which is stable in air. Catalysis Example 11 Use of a Pd-catalyst for the oxidation of glucose to gluconic acid. 100 ml of an aqueous solution of glucose with 16 g glucose (99 percent per weight) (88 mmole) and 0.24 g of the catalyst described in example 8 (1.5 percent per weight in relation to the amount of glucose) are transferred to a 250 ml stirring reactor equipped with gassing stirrer, thermometer, alkali metering, pH electrode and oxygen feeding. The oxygen is distributed at normal pressure by means of the gassing stirrer in the solution at a reaction temperature of 56°C. The resulting gluconic acid is neutralized by dropping 10 percent per weight of caustic soda thereto. Thereby, the pH value of the suspension is 10.0. The catalyst is filtered off, and the filtrate is analyzed by means of ion chromatography and HPLC. Conversion (min) : 49% Selectivity (120 min) : 92% Activity (120 min): 327 g [gluconic acid]/g [Pd] x hour Example 12 Use of a Pd-catalyst for the selective hydrogenation of 3- hexyne-1-ol to cis-3-hexene-l-ol 30.0 mg of a Pd-colloid/activated carbon catalyst, prepared according to example 9, are weighed in a 100 ml dropping funnel. The measuring of the selectivity is performed in a reactor which is thermostatted to -10°C. The dropping funnel is put upon the reactor, the whole apparatus is evacuated several times and flushed with hydrogen. Subsequently, the catalyst is placed into the reactor in hydrogen-counterflow with 100 ml of absolute, non-degenerated ethanol under argon in 2 portions of 50 ml, respectively. The dropping funnel is taken off and it is replaced by a septum. 10 ml 3-hexyne-l-ol are injected through the septum. After thermostatting the suspension at -10°C and pressure compensation, the path to a 1 1-precision buret which is sealed by mercury is opened. GC samples are taken through the septum by means of a syringe with filter aid and hypodermic steel needle in regular intervals until stoichiometric hydrogen take-up is attained. Selectivity according to GC: 94.9%. Example 13 Use of a Ru-catalyst for the partial hydrogenation of benzene to cyclohexene 10 ml benzene, 40 ml water with 3 g NaOH and 500 mg of the catalyst described in example 10 (1 percent per weight Ru/La 2 0 3 , 6.25 percent per weight of catalyst in relation to the amount of benzene) are filled into a 100 ml stainless steel autoclave. The content is stirred with the club stirrer and heated to 150°C. Now, it is pressed on to 50 bar of hydrogen pressure. The autoclave is taken from the heating jacket support after 30 min, and stirring is interrupted. Thereby, a hydrogen up-take of 18 bar can be noticed. The residual H 2 pressure is blown off after cooling, and a sample is taken from the upper organic phase which is examined by gas chromatography. Conversion(benzene) : 8.5% Selectivity (cyclohexene): 78.5%. Example 14 Preparation of a platinum colloid stabilized by dihydro- cinchonidine 0.104 g PtCl 4 (0.31 mmole) are dissolved in a 100 ml two-neck flask, provided with reflux condenser and a septum, in 83 ml water, and heated to reflux temperature in an oil bath. The temperature of the oil bath is 140°C (±5°C) during the synthesis. A solution of 0.092 g dihydrocinchonidine (0-.31 mmole) in 7 ml of 0.1 n. formic acid is rapidly injected through the septum. In the beginning, the reaction mixture becomes turbid and begins to become black colored after some minutes. The reaction is finished approximately ten minutes after the beginning of the black coloration. The reaction mixture is frozen in liquid nitrogen and liberated of water and the forming hydrochloric acid by freeze drying. A black powder is obtained which can be completely dispersed in water. If the formed platinum colloids should be applied on carrier materials, the aqueous product dispersion can be used without isolation of the metal particles before the application on the carrier. The yield is 0.18 g (103% of the theory) in this reaction. The elemental analysis shows 34.5% Pt, 16% Cl, 39.5% C, 5% H and 5% N. Electron-microscopic examinations show an average particle size of 2 nm. Example 15 Preparation of a heterogeneous platinum catalyst by adsorption of platinum colloids on silicon dioxide and active carbon 100 ml of the colloid, described in example 14, are directly taken up after the synthesis in 100 ml cold, distilled water, and are dropped during one hour to 100 ml of the carrier suspension. Either the highly disperse silicon dioxide Aerosil P 25 TM (Degussa) or the active carbon carri•er 196 (Degussa) which was oxidized with sodium hypochloride before the application to the carrier, can be used as carriers. The obtained suspensions are stirred with a magnetic stirrer at a low rotational speed during two days, and they are susequently filtrated. The filtrate is completely discolored, a fact from which it can be concluded that the metal colloids were quantitatively absorbed on the carrier. The thus obtained heterogeneous platinum catalysts were dried in a drying oven, and they can be used subsequently as hydrogenation catalysts without further intermediary step. A uniform and agglomeration-free distribution of the colloids on the carrier materials could be proven by electron-microscopic examinations. Example 16 Enantioselective hydrogenation of 2-keto-propane acid ethylester to 2-hydroxy-propane acid ethylester A 100 ml autoclave is charged with the catalyst described in example 15 (platinum on silicon dioxide; metal content 5%) , 5 ml 2-keto-propane acid ethylester (45 mmole) , 20 ml dihydrocinchonidine (0.1 mmole), 10 ml acetic acid and a magnetic stirrer nucleous having a size of 3 cm. The presure vessel is degassed after being closed, and subsequently, 100 bar hydrogen are pressed on under vigoreous stirring. The reaction takes place at 20°C, and it is terminated approxiamtely after 15 minutes. Following the expansion of the pressure vessel, the product mixture is liberated of the catalyst by filtration, the clear filtrate is taken up in 180 ml saturated sodium bicarbonate solution and subsequently extracted three times with each 20 ml of diethyl ether. The combined organic phases are concentrated on a rotary evaporator, the remaining clear solution is examined by NMR spectroscopy and mass spectroscopy, and it is identified as 2-hydroxy-propane acid ethylester. The yield was determined by gas chromatography to 90%. The optical yield of the reaction was examined by gas chromatography on a chiral column, and yields an excess of enantiomer of 81%. Table 2. Tenside stabilized colloids of metals of the groups Vlll-lb of the periodic system by reduction wi No Metal salt T Teennssiiddee MMeettaall ssaalltt/-- Reduction agent Solvent Reaction isolated M tenside conditions amount of product g/mmole g/mmole molar ratio mmole ml T, * C ' t, h 9 50 20 8,5 50 20 8,3 14 20 48 9.02 13 40 0,65 13 40 0,23 13 65 28 3,9 12 40 34 1,91 11 40 34 1,08 Table 2: continuation 1 No. Metal salt Tensidp Metal saltA Reduction agent Solvent Reaction isolated amount Metal content Water solubility in mg tenside conditions of product atom metal / 1 water g/mmole g/mmole molar ratio mmole ml T, "C t, h g % RhCI 3 A1 1:0,75 1BEI3H THF 40 34 0.87 Rh:25,2 410 0,452,15 0.541/1,61 6,45 105 1:0,5 LiBEt 3 H THF 40 34 0,67 Rh: 32,9 440 6,45 105 1:3 LiBEt 3 H THF 60 16 2,0 Rh: 10,1 180 6.45 120 1:2 LiBEt 3 H THF 60 16 1,60 Rh:13,1 170 6,45 120 1:3 LiBEt 3 H THF 60 16 2,0 Rh:10.1 140 6,45 120 1:2 iBEt 3 H THF 60 16 1,30 Rh: 16,2 110 6,45 120 1:2 LiBEt 3 H THF 25 16 2,64 Pd: 14.8 160 5,6 300 12 LiBEt 3 H THF 25 16 3,13 Pd: 13.35 280 1.37/7,75 5,2/15,5 10,8 500 Table 2, continuation 2 No Metal salt Tenside Metal snlt/- Reaction isolated amount Metal content Water solubility in mg tenside conditions of product atom metal /I water g/mmole g/mmole molar ratio T, "C t, h g % 1:2 25 24 2,99 Pd: 13,7 260 1:3 60 16 2.10 Ir: 8,99 370 1-2 20 24 1,96 Pt: 58,93 420 2,74/10,3 6.94/20.68 o 10 P1CI 2 A1 1.1 20 27 1,6 Pt-32,64 350 1.033,87 1.31/3,9 >1 PtCI 2 A1 1-0,5 20 27 1,46 Pt: 51,50 320 1.0a'3,87 0,655/1,95 22 PtCI 2 A2 12 25 16 16,24 Pt: 22,09 160 5,520,67 11.3/41,7 23 PtCI 2 A2 1:1 20 16 0,43 Pt:22,6 -170 0,133/0,5 0.138/0,5 24 PtCI A2 1-0.5 20 16 0,35 Pt:27,7 180 0,133/0.5 0,068/0,25 Table 2: continuation 3 No. Metal salt Tenside Metal salt/- Reduction agent Solvent Reaction isolated Metal Water solubility in mg tenside conditions amount of content atom metal / 1 water product g/mmole g/mmole molar ratio mmole ml C<C J.Λ 9 25 PtCt 2 A3 1 :2 LiBEt 3 H THF 20 108 2.0 Pt: 19,60 110 0,857/3,23 2,35 6,45 6,45 200 26 AgBr A1 1 -2 UBEt 3 H THF 20 24 2,82 Ag:11 ,52 130 1 ,36/5, 1 3,5 10,2 10.2 550 ro Table 3 Tenside-stabilized colloids of bimetals of the groups Vlll-lb of the periodic system by reduction with alkali BEt 3 H in THF ro ro Table 3 continuation No Metal salt Tenside Metal salt/- Reduction agent Solvent Reaction isolated amount of Metal Water solubility tenside conditions product content in mg atom metal/ 1 water g/mmole g/mmole molar ratio mmole ml T, * C t, h % 9 P1CI 2 - RhCI 3 A1 1-2,55 50 28 3,60 Pt: 25,0 380 1 ,80/6,79 - 1 ,41/6,74 11 ,56/34,45 Rh:11,1 10 PtCI 2 - RhCI 3 A1 1.2,8 60 24 4.4 Pt: 13,89 370 0,88'3,32- 2,7613,18 15,5/46,19 Rh:16,3 11 PtCι 2 -PdCI 2 A1 12 20 24 5,13 Pt: 8,42 350 1,03/3,88-0,683,88 5,2/15,5 ■ Pd: 4,45 ro 1 2 PtCI 2 - lrCI 3 A1 12.1 60 16 16,03 Pt: 17,3 430 3.99/15.0 - 0,49/1 ,67 11 ,74/35,0 In 1,87 " 3 P1CI 2 - lrCI 3 A1 12,5 60 16 14,4 Pt: 8,8 410 1,867,0-2,09/7,0 11.74/35,0 Ir: 8,6 14 PtCI 2 - lrCI 3 A1 12,9 60 64 18,22 Pt: 1,4 400 0,37/1,4-3,7612,6 13,6240,6 Ir: 13,0 ι5 PtCI 2 - lrCI 3 A2 12,1 60 16 10,65 Pt: 15.3 190 399/15,0-0,49/1,67 9,48/35,0 Ir: 1,6 Table 4: Tenside-stabilized colloids of metals of the groups Vlll-lb of the periodic system by reduction with alkali metal boron hydrides in H 2 0 and alcohols, respectively No Metal salt Tenside M Meettaall ssaalltt//-- RReedduuccttiioonn Solvent Reaction isolated amount of Metal Water solubility tenside agent conditions product content in mg atom metal / I water g/mmole g/mmole molar ratio mmole ml T. 'C t, h 40 1 ,24 Ru: 7,65 430 40 0,42 Ru: 9,87 425 20 1 ,14 Rh: 8,25 450 no 24 7,3 Rh: 5,5 110 20 24 0,92 Pt: 9,8 355 20 4.8 Pt.: 10,2 360 8, 1 Pt: 9,5 120 Table 5: Tenside-stabilized colloids of bimetals of the groups Vlll-lb of the periodic system by reduction with alkali metal boron hydrides in H 2 0 and alcohols, respectively No Metal salt Tenside Metal salt/- Reduction agent Solvent Reaction isolated amount of Metal Water solubility tenside conditions product content in mg atom metal /I water g/mmole g/mmole molar ratio mmole ml T, °C t, h H 2 PtCI 6 - CuCI 2 x H 2 0 A1 1 :3,84 20 7,05 Pt: 7,02 390 1,35/2,65-0,11/0,66 4,3/12,7 Cu: 0,52 H 2 PtCI 6 -CuCI 2 H 2 0 A2 1:8 20 8,5 Pt: 6,0 170 1 ,35/2,65 - 0,05/0,295 6,4/23,6 Cu: 0,2 RhCI 3 x H 2 0 - lrCI 3 x H 0 A1 1 :4 20 7,06 Rh: 2,7 340 0.7/2,65-0,8/2,65 7,221,2 Ir: 5.0 RnCI 3 x H 2 0 - RuCI 3 x H 0 A1 1 :4 20 10,52 Rh:2,3 410 0,7/2,'65-0,7/2,65 7,221,2 Ru:2,3 RuCI 3 x H 2 0 - lrCI 3 x H 2 0 A1 1 :4 20 8.7 Ru:2.6 450 0,7/2,65-0,82,65 7,2/21,2 Ir: 4,9 H 2 RCI 6 -RuCI 3 xH 2 0 A1 1:4 20 10.36 Pt: 4,5 380 1,35/2,65-0,7/2,65 7,2/21,2 Ru: 2,2 H 2 P1CI 6 - RuCI 3 x H 2 0 A1 1:4 24 8,02 Pt:4,7 120 1,35/2,65-0,7/2,65 7,2/21,2 Ru:2,3 • i 2 PtCI 6 - RhCI 3 xH 2 0 Λ1 1:4 20 12,1 PI: 4,3 360. • 35/2,65- 0,7/2,65 7.2/21,2 Rh:2,0 Table 5 continuation No Metal salt Tenside Metal Reduction Solvent Reaction isolated salt/- agent conditions amount of tenside product g/mmole g/mmole molar g/mmole ml T, t, h g ratio 8 H PtCI 6 - RhCI 3 x H 0 A1 1:4 20 10,58 1,35/2,65-0,7/2,65 7,2/21,2 10 H 2 PtCI 6 - PdCI 2 x 2 H 2 0 A1 1:4 20 11,1 1,35/2,65-1,0/2,65 7,2/21,2 11 H P1CI 6 - Pd(N0 3 ) 2 x H 2 0 C1 20 10,2 0,55/1,06-1,1/4.24 7,0/- 12 H 2 PtCI 6 - lrCI 3 x H 2 0 A1 1:4 20 10,34 1,35/2,65-0,82,65 7,2/21,2 13 H 2 PtCI 6 - lrCI 3 x H 2 0 A1 1-4 20 10,2 1,35/2,65-0,8/2.65 7,2/21,2 TableJS Tenside-stabilized colloid of metals of the groups Vlll-lb of the periodic system by reduction with hydrogen in H 2 0 No Metal salt Tenside M Meettaall RReedduuccttiioonn Solvent Reaction isolated amount of Metal Water solubility salt/- agent conditions product content in mg atom tenside metal /I water g/mmole g/mmole molar T, t, h P.bar ratio • c ' RuCI 3 x3H 2 0 A1 1:3 H 2 H 2 0 60 10 1 0,43 10,98 370 0,250,95 0,96/2,89 100 2 RuCI 3 A1 1:3 H 2 H 2 0 60 16 50 0,22 9,41 375 0,160,78 0,79/2,34 100 3 RuCI 3 x3H 2 0 A2-K 2 C0 3 1:3 H 2 H 2 0 60 0,38 7,1 160 ro 0 , 22/0 , 84 0,68/2,53 - 0,23/1 ,67 80 4 Ru 2 (OAc) 4 A1 1:6 H 2 H 2 0 60 16 50 0,41 8,78 210 0.27/0,62 1,25/3,7 100 5 Ru(Acac) 3 A1 1:3 H 2 H 2 0 60 16 50 0,35 9,37 340 0,39/0,97 0,98/2,91 100 5 RhCI 3 3H 2 0 A1 1:3 H 2 H 2 0 20 1,02 11,40 330 0,42/1,6 1,62/4,81 60 7 RhCI 3 x3H 2 0 A2 1:3 H 2 H 2 0 20 0,85 10.73 150 0,40/1,52 1,24/4,57 100 ft PdBr 2 A1 -LI 2 C0 3 1:4 H H 2 0 20 9,6 5,3 290 1,45,3 7,221,2-0,4/5,3 100 Table 6 continuation 1 No Metal salt Tenside Metal Reduction Solvent Reaction isolated amount of Metal Water solubility salt- agent conditions product content In mg atom tenside metal /I water g/mmole g/mmole molar ml T, t, h P, bar g % ratio • c H 2 P1CI 6 x 6 H 2 Q A1 - Na 2 CQ 3 1:4 H 2 0 20 12,6 7,1 360 2.7/5,3 7,2/21,2-3,4/31,8 100 10 PtCI 2 A1 -K C0 3 1:4 H 2 0 20 1,5 1 8,79 9.7 330 1,4/5,3 7,2/21.2-0,735,3 100 11 PtCI 2 A1 - K 2 C0 3 1-4 Ho H 2 0 20 8,5 10,1 310 1,45,3 7,221,2-0,73/5,3 100 ro 12 PtCI 2 A1 - Na 2 C0 3 1:4 H 2 00 H 2 0 20 1.5 1 9,0 10.8 350 1, '45,3 7,2/21,2-0,56/5,3 100 13 PiCI 2 A1 -Li 2 C0 3 1:4 H 2 H 2 0 20 140 10,3 370 21 79,6 108/318-6/79,5 1500 14 P1GI 2 A1 - LI 2 C0 3 1-2 H 2 H 2 0 20 73,7 17,9 450 21/79.5 54/159-339,75 1500 15 PtCI A1 - Li 2 C0 3 1 H 2 H 2 0 20 8,4 10,7 380 1,4/5,3 7,2/21,2-0,4/5,3 100 \ P,CI 2 A1 - ι 2 C0 3 1 p ιι 2 o 20 6.1 16,4 440 1 V53 3.6/10,6-0,22,65 100 Table 6 continuation 2 No Metal salt Tenside Metal Reduction Solvent salt/- agent tenside g/mmole g/mmole molar ml T, t, h P, bar ratio • c 17 PtCI 2 A1 - LI 2 C0 3 14 H 2 0 20 1,5 1 9,5 10,4 380 14/53 7,2212 - 0,4/5,3 100 18 PtCI 2 A1 - LiBr 14 H 2 0 20 9.7 9,8 360 14/53 7,221,2-0,5/5,3 100 19 PtCI 2 A1 - LiBr 1-2 H 2 H 2 0 20 61 16,9 370 ro 14/53 3,610,6-0,25/265 100 CD 20 PtCI 2 A2 - Lι 2 C0 3 H 2 H 2 0 20 14,1 7,1 160 14/53 11,5/42,4-0,810,6 100 ?ι Ptcι 2 A4 - Lι 2 C0 3 18 H 2 H 2 0 20 17,3 5,7 110 14/53 14.6/42,4-0,810,6 100 22 PlCI 2 B1 - Lι 2 C0 3 14 H 2 H 2 0 20 25,1 4,1 105 1 ,4/5,3 21.7/21,2-0,4/5,3 100 23 PtCI 2 D1 - Li 2 C0 3 Ho H 2 0 20 9.5 10,6 130 14/53 II- - 0,4/5,3 100 24 PtCI 2 C1 - Li 2 C0 3 H 2 H 2 0 20 9.7 10,6 145 Table 6: continuation 3

Claims: l a i m s Process for producing tenside-stabilized colloids of mono- and bimetals of the groups VIII and lb of the periodic system having particles sizes of 1-10 nm, characterized in that metal salts are reacted in the presence of strongly hydrophilic tensides selected from the group consisting of amphiphilic betaines, cationic tensides, fatty alcohol polyglycol ether, polyoxyethylene-carbohydrate-fatty alkylester and/or anionic tensides and/or amphiphilic sugar tensides, in THF, alcohols, or directly in water, with chemical reduction agents such as hydrides, -hydrogen or alkali formate, between 0°C and 100°C at normal pressure, optionally by adding alkali carbonates and/or ammonium chloride, and that the precursors are isolated from the thus prepared solutions of >100 mg atom metal/1. Process for producing carrier supported metal colloid catalysts by using preformed, tenside-stabilized mono- and bimetalic colloids of metals of the groups VIII and lb of the periodic system according to claim 1, characterized in that the colloids stabilized by tensides are used in the form of solutions for adsorptive coverage of carriers. Tenside-stabilized colloids of mono- and bimetals of the groups VIII and lb of the periodic system having particles sizes of 1-10 nm, characterized by a surface area coverage with strongly hydrophilic tensides, selected from the group consisting of amphiphilic betaines, cationic tensides, fatty alcohol polyglycol ether, polyoxyethylene-carbohydrate-fatty alkylesters and/or anionic tensides and/or amphiphilic sugar tensides, which are obtainable by chemical reduction with reduction agents such as hydrides, hydrogen or alkali formate, of metal salts in the presence of tensides between 0°C and 100°C at normal pressure, optionally by adding alkali carbonates and/or ammonium chloride, and isolation of the precursor from the thus prepared solutions of >100 mg atom metal/1. 4. Colloids according to claim 3, characterized in that the strongly hydrophilic tensides are selected from particularly nonionic tensides having HLB-values of > 8. 5. Use of the tenside-stabilized colloids of mono- and bimetals, obtainable according to claims 1 and 2, as precursors for producing metal colloid-heterogeneous catalysts by adsorption from aqueous solution onto inorganic or organic carrier materials.- 6. Use according to claims 1 to 5, characterized in that the metal colloids are used in concentrations of up to 25 percent per weight of metal content in relation to the total weight of the solution. 7. Use of the metal colloid-heterogeneous catalysts Pt-A- activated carbon, Pd-A-carbon, Pd/Pt-A-carbon, obtainable according to claim 5, for the partial oxidation of primary alcohol functionalities " in carbohydrates. 8. Use according to claims 1 to 5, characterized in that carbon carriers, ceramic oxides, carbonates, sulfates or zeolites in the form of powders or formed bodies are used as carriers. 9. Use of the palladium colloid-A-carbon-catalysts, respectively, Pd-colloid-CaC0 3 -catalysts, obtainable according to claim 5, for the selective cis-hydrogenation of C-C- triple bonds. 10. Use of the heterogeneous catalysts on oxides of the metal oxides of the lanthanoids, prepared according to claim 5, as carrier for the selective hydrogenation of benzene to cyclohexene. 11. Use of the rhutenium-lanthanoidoxide-heterogeneous catalysts, obtainable according to claim 10, for the selective hydrogenation of benzene to cyclohexene. 12. Mono- and bimetalic colloids (particle size 1-10 nm) from Cu, Ru, Rh, Pd, Ir, Pt * Ag, Ru/Fe, Pt/Co, Pt/Rh, Pt/Pd, Pt/Ir, Pt/Cu, Pt/Ru, Rh/Ir, Rh/Ru, Ru/Ir which are alkali-free stabilized hydrophilically with 3-(N,N- dimethyldodecyl amommonium)propane sulfonate, and being soluble in water at a concentration of > 100 mg atom metal/1. 13. Mono- and bimetalic colloids (particle size 1-10 nm) from Ru, Rh, Pd, Pt, Pt/Co, Pt/Ni, Pt/Ir, Pt/Cu, which are hydrophilically stabilized with lauryldimethyl carboxymethyl ammonium betaine, and being soluble in water at a concentration of > 100 mg atom metal/1. 14. Ru- and Pt-colloids (particle size 1-10 nm) which are hydrophilically stabilized with cocoamidopropyl betaines, and being soluble in water at a concentration of > 100 mg atom metal/1. 15. Platinum colloids (particle size 1-10 nm) which are hydrophilically stabilized with C χ ,H 37 OH Cl 1+ I I Cl CH 3 —N CH 2 CH ",CH CH, and being soluble in water at a concentration of > 100 mg atom metal/1. 16. Platinum colloids (particle size 1-10 nm) which are hydrophilically stabilized with (R R = alkyl radical of partially hydrogenated palm grease, and being soluble in water at a concentration of > 100 mg atom metal/1. 17. Mono- and bimetalic colloids (particle size 1-10 nm) from Ni, Co, Pt, Pt/Pd which are hydrophilically stabilized with polyoxyethylene laurylether, and being soluble in water at a concentration of > 100 mg atom metal/1. 18. Platinum colloids (particle size 1-10 nm) which are hydrophilically stabilized with polyoxyethylene sorbitan monolaurat, and being soluble in water at a concentration of > 100 mg atom metal/1. 19. Platinum colloids (particle size 1-10 nm) which are hydrophilically stabilized with Na-cocoamidoethyl-N- hydroxyethyl-glycinate, and being soluble in water at a concentration of > 100 mg atom metal/1. 20. Platinum colloids (particle size 1-10 nm) which are hydrophilically stabilized with alkylpolyglycoside, and being soluble in water at a concentration of > 100 mg atom metal/1. 21. Carrier fixed heterogeneous metal colloid catalysts comprising mono- and bimetals of the groups VIII and lb of the periodic system, obtainable by the use of solutions of preformed tenside-stabilized mono- or bimetal colloids of said metals by adsorptive coverage of said carriers. 22. Catalysts according to claim 21 comprising inorganic or organic carrier materials. 23. Catalysts according to claim 21, characterized in that the carrier materials comprise carbon carriers, ceramic oxides, carbonates, sulfates or zeolites in the form of powders or formed bodies. 24. Catalysts according to one or more of the claims 21 to 23 characterized by a coverage comprising oxides of lanthanoide elements, in particular lanthanum oxide.

Inventors: BOENNEMANN HELMUT, BRIJOUX WERNER, BRINKMANN RAINER, RICHTER JOACHIM, BOENNEMANN, HELMUT, BRIJOUX, WERNER, BRINKMANN, RAINER, RICHTER, JOACHIM
Applicants: BOENNEMANN HELMUT, BRIJOUX WERNER, BRINKMANN RAINER, RICHTER JOACHIM, STUDIENGESELLSCHAFT KOHLE MBH, BOENNEMANN, HELMUT, BRIJOUX, WERNER, BRINKMANN, RAINER, RICHTER, JOACHIM
Application year: 1995
Main classification: B01J37
IPC codes: B01J35, B01J37, C07C5, C07C215, C07C219