Untersuchungen zur Acidität und katalytischen Spaltaktivität dekationisierter NaY-Zeolithe

Investigation on Acidity and Catalytic Activity of Deep-Bed Calcinated Zeolites NH₄ NaY NMR and infrared techniques are applied to decationated zeolites NaY to study Brönsted acidity. The results are compared with measurements of catalytic activity and crystallinity of this zeolites. The number of OH groups which are able to form a pyridinium ion (PyH⁺) increases with increasing exchange degree and with increasing temperature of the sample. The rate of pyridinium ion formation as an equivalent of Brönsted acidity and the catalytic activity increase similarly with increasing exchange degree up to such values where a loss of crystallinity occurs.     

Untersuchungen zur Acidität und Basizität von Alkoxysilylaminen

Investigations on Acidity and Basicity of Alkoxysilylamines Relative acidity and basicity have been determined for silylamines of the type (RO)₃Si? NH? X (R = Et, n. Pr, i-Pr, s-Bu, t-Bu; X = n-Bu, Ph, p-MeO? C₆H₄, p-Cl? C₆H₄, p-NO₂? C₆H₄) by IR, NMR, and potentiometric investigations. The position of the ν_NH band, the shift of this band in tetrahydrofuran and the chemical shift of NH-proton-NMR signal show a significant increase of NH acidity with increasing electron attracting effect of R and X. The shift of deuteriochloroform ν_CD band at association with aminosilanes and the results of potentiometric investigations confirm the low basicity of these compounds and the decrease of the basicity with increasing acidity.     

Untersuchungen an Metallkatalysatoren. XXVIII [1]. Zur Aktivität und Selektivität von Nickel/Träger-Katalysatoren

Investigations on Metal Catalysts. XXVIII. Activity and Selectivity of Supported Nickel Catalysts Titania and alumina supported nickel catalysts (with 1 and 10 wt.-% Ni, resp.) have been tested in ethane hydrogenolysis and conversion of cyclohexane. Titania supported nickel and nickel on high surface aluminas are characterized by small hydrogenolysis activities and high dehydrogenation selectivities. The behaviour of the Ni/Al₂O₃ catalysts is discussed in terms of an interaction between small nickel crystallites and unreduced nickel. In the case of the Ni/TiO₂ catalysts the interpretation is based on the partial poisoning of the nickel surface by titanium cations.     

Untersuchungen zur Basizität von Alkyl- und Silylakylaminen

Investigations on the Basicity of Alkyl and Silyl Alkylamines The basicity of N has been investigated in primary and secondary alkyl und silyl alkylamines by means of the v_C–D band shift of CDCl₃ associated to the amine group by potentiometrically determined pK_s-values, and by mass spectroscopically measured ionisation potentials. The results show a dependence on electronic and steric effects, but they do not give arguments for a conjugative interaction between N and Si,     

Untersuchungen an Metallkatalysatoren. 37. Zum Einfluß der Beladung auf Aktivität und Selektivität von Nickel/Träger-Katalysatoren

Investigations on Metal Catalysts. 37. On the Influence of the Loading on Activity and Selectivity of Supported Nickel Catalysts Strong metal-support interactions effect a distinct decrease of the hydrogenolysis activity. They can be detected with diminishing metal loading in the following order: Ni/TiO₂ > Ni/Al₂O₃ > Ni/SiO₂. Strong metal-support interactions mean an influence on the electronic properties of the metal crystallites. On the other hand a mechanical mixture of nickel and η-Al₂O₃ is more active in hydrogenolysis than nickel.     

Untersuchungen an oxidischen Katalysatoren. XXV. Katalytische Aktivität und Aktivitäts-Zeit-Verhalten modifizierter Mordenite beim Spalten von n-Octan

Studies on Oxide Catalysts. XXV. Catalytic Activity and Aging Properties of Modified Mordenites in the Cracking of n-Octane MeH-mordenites (Me = Li, K, Mg, Ca, Ba) were prepared by ion exchange starting with H-mordenite (SiO₂/Al₂O₃ mole ratio = 14). To characterize these samples the cracking of n-octane was used as catalytic test reaction. Surface OH groups and the adsorption of NH₃ on these samples were investigated by i. r. spectroscopy. Unaffected by the kind of the exchanged cation the Brönsted acidity of the H-mordenite decreases monotonously with increasing content of the incorporated cation. The catalytic activity and (to a much higher degree) the rate of deactivation by coking during the reaction decrease as the Brönsted acidity decreases. The strong dependence of the Brönsted acidity on the deactivation rate points to a multi-site mechanism of the coking process.