Kreislaufführung von verbrauchten Katalysatoren in der chemischen Industrie

Recycling of Used Catalyst in the Chemical Industry In this article, the consumption of catalysts in the chemical industry in Germany as well as their recycling are investigated. Metal catalysts play a dominant role both quantitatively and economically. Precious metal catalysts are also used very often, however, their quantitative use is, with less than 1 000 t per annum, small and they are regularly reclaimed. The biggest group of catalysts consists of non‐precious metal catalysts and it represents ca. 9 000 t per annum. The used catalysts from this group are only partially recycled. Some of these metals are often reclaimed, such as Ni, Cr, Mo, Co, and Cu. The catalysts that are not recycled are utilized in the chemical industry or disposed of. Economical criteria, such as the price of the metal, the content of the metal, the impurities, etc., are usually decisive for the choice between recycling and disposal. The support material can also be re‐utilized or disposed of.     

Komplexkatalyse mit Technetiumverbindungen: Hydroformylierung mit Technetiumcarbonyl-Katalysatoren

Complex Catalysis with Technetium Compounds. Hydroformylation with Technetiumcarbonyl Catalysts The hydroformylation reaction of cyclohexene ( 1 ), propene ( 2 ) and 1-octene ( 3 ) was studied using Tc₂(CO)₁₀ and Tc(CO)₁₀/P(n-C₄H₉)₃, resp., as catalysts in solution. For comparison experiments have also been made with Mn₂(CO)₁₀, Mn₂(CO)₁₀/P(n-C₄H₉)₃ and Re₂(CO)₁₀/P(n-C₄H₉)₃ as catalysts for the hydroformylation of 1 . There is always a competition between hydrogenation and hydroformylation. Tc₂(CO)₁₀/P(n-C₄H₉)₃ gave the best results in activity and selectivity within the subgroup VII complexes studied, but is a rather poor catalyst compared with the cobalt or rhodium compounds.     

Hydroformylierung mit wasser- und methanollöslichen Rhodiumcarbonyl/Phenyl-sulfonatoalkylphosphan-Katalysatorsystemen – Ein neues Konzept für die Hydroformylierung höhermolekularer Olefine

Hydroformylation with Water- and Methanol-soluble Rhodium Carbonyl/phenyl-sulfonatoalkyl-phosphine Catalyst Systems – A New Concept for the Hydroformylation of Higher Molecular Olefins The heterogenization of the homogeneous hydroformylating catalyst system enables the recovery of the catalyst from the reaction products by a simple phase separation but it is unfavourable that many advantages of the homogeneous catalysis are given up by this procedure. To avoid this drawback we used rhodium carbonyl/tert. phosphine catalyst systems soluble as good in methanol as in water for the homogeneously catalyzed hydroformylation of the olefin in methanolic solution. Only after reaction the product mixture is heterogenized by adding water forming an aqueous phase containing the catalyst system. It was shown by the hydroformylation of n-tetradecene-1 with rhodium carbonyl/phenyl-sulfonatoalkyl-phosphine catalyst systems that this new conception is very useful for the oxo reaction of high-molecular olefins.     

Untersuchungen zur Aktivitätsveränderung eines mit Fettsäuren passivierten Katalysators

Investigations Concerning Changes in Activity of a Catalyst Passivated by Fatty Acids The possibility of passivating the Ni-catalyst by fatty acids on kieselguhr at a temperature of 75°C in an unmixed system during 168 hours was tested. The activity of the catalyst depended on the degree of reduction, the specific surface and the time of passivation. During passivation a correlation of the system Ni-NiO with the fatty acids by formation of Ni-soaps (max. 27% p. weight) took place.     

Die Wechselwirkung Laurin- und Stearinsäure/Ni-NiO-System des Katalysators

The Interaction between Lauric and Stearic Acid and the Ni-NiO Catalyst System The reactivity of the Ni-NiO catalytic system of following degrees of reduction: 0, 35–65 and 100% Ni with the pure chemical quality lauric and stearic acids during the catalyst passivating conditions 75–115°C were followed in the time period 0–100 hours. The quantity of interaction product of nickel salts of fatty acids in the catalyst is controlled both of the initial reactivity of the Ni-NiO system with the fatty acids and of the kinetics of the zero reaction order. Although the lauric acid is expressively more reactive than the stearic acid, the activity of the in this way prepared catalysts tested in hydrogenation of free fatty acids did not show significant differences.     

Kontinuierliche Reaktionsführung mit löslichen Enzymen

Continuous processes with soluble enzymes. This paper surveys the use of continuously operating enzyme-membrane reactors with enforced flow where the retention of soluble enzymes in the reaction vessel is achieved by means of an ultrafiltration membrane. This technique has been commercialized in the acylase process for the synthesis of L -amino acids on a 200 ton/year level. It is especially useful for the application of multi-enzyme systems with cofactor regeneration. The synthesis of L -tert-leucine from the corresponding α-keto acid has been achieved on a kilogram scale. Coenzymes coupled to water soluble polymers are retained in the membrane-reactor together with the enzymes. Use of suitable conditions prevents loss of enzyme and coenzyme by passage through the membrane or by deactivation. Therefore the costs of enzymes and coenzymes are no longer limitations for economic processes. In the continuously operating enzyme-membrane reactor regeneration of the coenzyme up to 600 000 times was achieved. In continuous peptide synthesis space-time yields of 25 kg/(l d) were obtained. To suppress side reactions very high catalyst concentrations are possible, yielding residence times below 4 min.