TY - CONF A1 - Jancke, Harald A1 - Altenburg, Wolfgang T1 - NMR Studies an Soil and Peat - The Problem of True Signal Intensities T2 - 2nd European Symposium "NMR in Soil Science" CY - Freising/Weihenstephan, Germany DA - 2000-02-27 KW - NMR KW - Signal Intensities PY - 2000 SP - 1 EP - 27 AN - OPUS4-762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jäger, Christian A1 - Maltsev, Sergey A1 - Malz, Frank A1 - Karrasch, Andrea A1 - Altenburg, Wolfgang T1 - Nanoskalige Calciumphosphate, Oberflächenstrukturen und Wechselwirkung mit organischen Molekülen: Was kann die NMR? PY - 2005 SN - 1616-0177 SN - 0011-8656 VL - 6 IS - 3 SP - 232 PB - Verl. Neuer Merkur CY - München AN - OPUS4-11609 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nofz, Marianne A1 - Pauli, Jutta A1 - Dreßler, Martin A1 - Jäger, Christian A1 - Altenburg, Wolfgang T1 - 27Al NMR Study of Al-Speciation in Aqueous Alumina-Sols N2 - A new method of preparing concentrated alumo-sols, the hydrolysis of Al-tri-sec-butylate in acidic aqueous media at 85°C, was studied in detail by varying the H2O/Al- and NO3 -/Al-ratios in wide ranges. The components of the sols were characterized by 27Al NMR spectroscopy. The pH-value depends on both the chosen H2O/Al- and NO3 -/Al-ratio and on the aging time of the sols and reflects the composition of the sols. Al13 polycations were detected in sols with a pH-value between 3.0 and 3.7. As a new result its presence was shown by NMR below 3.4. The Al13 content of the sols increased with pH and the maximum fraction of Al13 polycations was detected in the sol with the highest pH (3.7). Nearly 65% of the entire aluminium content of this solution is bound in the Al13 polycations. Hence, a new synthetic method for the preparation of Al13 ions containing sols was developed. Aging studies of the sols showed, that the Al13 polycations were more stable in solutions with higher pH-value. Al13 polycations were detected after an aging time of four months only in sols with a pH-value of 3.7. Tempering the aged sols at 40° to 80°C caused formation of Al13 and also of Al30 polycations. KW - Alumo-sol KW - Al13 polycations KW - Al-27 NMR spectroscopy PY - 2006 SN - 0928-0707 SN - 1573-4846 VL - 38 IS - 1 SP - 25 EP - 35 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-12350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, W. A1 - Kurzhals, R. A1 - Sauerbeck, S. A1 - Toufar, H. A1 - Buhl, J.-C. A1 - Gesing, T. A1 - Altenburg, Wolfgang A1 - Jäger, Christian T1 - Hydrothermal stability of zeolite SAPO-11 N2 - The hydrothermal stability of SAPO-11 was studied in water of autogenous pressure as function of the temperature. SAPO-11 remained crystalline up to 190 °C. Thereby, it was observed, parent as well as hydrothermally treated samples showed similarities to the isotypic structure of zeolite AlPO-11 called here AELdry. After fully hydration of the samples, AELdry changed completely into a hydrated AELwet structure of another framework symmetry. The transition from calcined to hydrated state was reversible for both the parent and the hydrothermally treated samples. 27Al and 31P NMR MAS spectra showed a single resonance typical for AlPO4 type tetrahedra for the calcined parent and hydrothermally treated samples. Upon hydration, the single AlPO4 resonance signal split into three different signals as is the case for the corresponding 31P signals. By means of NH3-TPD measurement a loss of acidity was detected after the hydrothermal treatment as follows from a framework desilication. Nitrogen and water adsorption decreased systematically. At 210 °C a non-zeolitic, non-porous phase was irreversibly formed. The XRD pattern of this phase shows resemblance to a synthetic aluminium phosphate of the tridymite structure type. KW - Zeolite KW - Silicoaluminophosphate KW - SAPO-11 KW - Hydrothermal stability KW - Phase transformation PY - 2010 DO - https://doi.org/10.1016/j.micromeso.2009.08.003 SN - 1387-1811 SN - 1873-3093 VL - 132 IS - 1-2 SP - 31 EP - 36 PB - Elsevier CY - Amsterdam AN - OPUS4-21131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -