Systematik bei der Entwicklung von Katalysatoren für Oxidationsreaktionen

Systematic approach to development of catalysts for oxidation reactions . The systematic catalyst development presented here for the example of a typical oxidation reaction shows that a systematic procedure is of value for a purposeful approach, and that statistically based planning and evaluation of experimental results represents an efficient tool. Physicochemical methods of study can provide important support for an understanding of catalytic action, with reaction-engineering studies in various kinds of reactors necessarily playing a central role in catalyst development. Technical and economic assessment of a catalyst under development is already feasible in laboratory experiments and ultimately decides for or against its technical applicability. Understandably, the scale-up of a production procedure developed in the laboratory to industrial quantities may also be beset with other problems which cannot be considered here.     

Katalysatoren für den Umweltschutz

Catalysts for environmental protection. The main emitters of anthropogenic air pollution are internal combustion engines, power plants, and production processes. Components of exhaust gases which are regarded as pollutants are hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO_x), sulfur dioxide (SO₂), and dust. Three main types of catalyst are understood to improve the environment; namely automotive emission control, NO_x abatement and oxidation. To reduce the pollutants HC, CO, and NO_x in automobile exhaust gas, three-way catalysts are currently applied. The reduction of particle emissions in diesel exhaust gas is achieved by diesel filters and oxidation catalysts. Pollutants from power plants are mainly the inorganic components NO_x and SO₂. In the SCR process, NO_x is catalytically reduced to nitrogen and water. The DESONOX process is suited for the simultaneous catalytic abatement of NO_x and SO_x. Exhaust gases from production processes in many areas require after-treatment. Therefore catalyst formulations depend on process parameters and exhaust gas components. This overview presents and explains catalyst types, design, mode of operation, and processes.     

Grundierungen für organische Dispersionsanstriche auf siliciumorganischer Grundlage und Emulsionsanstriche für Fassaden mit Siliconharzen als Bindemittel

Primers for Organic Dispersion Paints based on Organo-Silicons and Emulsion Paints with Silicon Resin Binders for Buildings It is possible to prepare water resistent, porous cement paints with silicon resin dispersions. Emulsion paints based on silicon resins are completely porous and they can be applied on absolutely fresh plasters even under the most difficult weather conditions. The water content of plaster and the building material was followed by continuous measurements. Alkalisiliconates and certain silicon resin solutions are porous primers for organic binder paints.     

Miniaturisierte Messzellenversuche als potenzielles Auslegungswerkzeug für Kolonnen mit strukturierten Packungen

Structured‐packing columns are widely used equipment for distillation and absorption processes in the chemical industry. For a highly promising design approach using miniaturized experimental setups, the design and evaluation of two developed miniaturized experimental setups is presented. The miniaturized experimental setups are meant to define characteristic parameters of fluid dynamics. Results of the liquid holdup from both setups are compared against existing correlations and measurements in a pilot plant.     

Phenylquecksilberverbindungen als Konservierungsmittel für Kosmetika

Phenyl-Mercuric Compounds as Preservatives for Cosmetics 0.005 to 0.01% phenyl-mercuric salts are adequate for the preservation of cosmetics. According to the literature this preservative action is almost completely neutralized by compounds containing SH-groups, whereas the experiments carried out by the author showed that 2% solutions of degraded horn keratin at pH 8 can be preserved with 0.01 to 0.005% phenyl mercuriacetate. Addition of 0.3% sodium lauryl sulphate improved the action. Sensitivity tests carried out on 12 persons who were hypersensitive to mercury showed positive reactions only in two cases.     

Acetessigaldehyd-dimethylacetal als Ausgangsstoff für Synthesen

Acetoacetaldehyde Dimethylacetal as a Starting Material for Syntheses The use of acetoacetaldehyde dimethylacetal (1) leads to the introduction of the group \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm =}\mathop {\rm C}\limits^{\mathop |\limits^{{\rm CH}_{\rm 2}}} ---{\rm CH}_{\rm 2} ---{\rm CH(OCH}_{\rm 3} {\rm)}_{\rm 2} $\end{document} by reaction at the carbonyl carbon atom, and of the group CH₃–CO–CH₂–CH?or CH₃–CO–CH?CH– by reaction at the acetalic carbon atom. For synthetic purposes it is important that methanol can be splitten off from 1, and the acetoacetaldehyde enol ether methoxybutenone (2) is generated. With catalytic amounts of acids or bases an equilibrium mixture with 70% 1 and 30% 2 is formed; 2 shows the higher reactivity of a vinylogous acetic ester. 1 as well as 2 can be attacked at each of the four carbon atoms; ring closure reactions were observed with the carbon atom 2 or 4 alone, or with two carbon atoms (6 possibilities, prevalent 2 + 4), and occasionally by participation of two molecules of 1 or 2.     

Thermogravimetrie als brennbarkeitsbestimmungs-methode für lineare polyurethane

In the present work oxygen index (OI) measurements and thermogravimetric analysis (TG) for a series of polyurethanes based on diols and isocyanate were conducted. It was found that a correlation exists between some of the thermal degradation parameters obtained from TG and OI-values. Analysis of experimental results confirms that the amount of mass loss at 250°C is directly proportional to the OI-value. It was also found that the logarithmic temperatures of maximal decomposition rates are directly proportional to the OI-values.     

Telechele als bausteine für neuartige polymere

The developments in the syntheses of α,ω-bifunctional oligomers (telechelics) are revued. Telechelic soft segments are synthesized by cationic, anionic and radical polymerization of vinyl and heterocyclic monomers. Telechelic PTHF obtained with CH₃CO⁺/Ac₂O stems from an equilibrating process and not from a transfer reaction. Telechelic polyisobutene is formed by the inifer technique of Kennedy. The use of lithium initiators with protected functional groups in butadien polymerization results in products with high 1.4-content. The group transfer polymerisation is specially suited to prepare telechelic PMMA of narrow molecular weight distribution. The “dead end” polymerisation is a necessary condition to obtain a functionality of two by radical polymerization. The synthesis of telechelic hard segments of the PPO and PPS type is described.