Ralph Herrmann

Stability of AlPO and SAPO molecular sieves during adsorption-desorption cycles of water vapor investigated by in-situ XRD measurements

Abstract To gain some information about the hydrolytic stability of AlPO and SAPO molecular sieves structural changes during adsorption and desorption cycles of water vapor have been studied by in-situ XRD diffractometry.

In-situ ultrasonic methods for monitoring the hydrothermal synthesis of LTA-type zeolite from colloidal solutions

Abstract In the present study, we report the successful use of ultrasound device as a real-time, in situ diagnostic tool for monitoring the crystallization progress of zeolite A from homogeneous colloidal solutions with the composition 0.4 Na2O : 10 SiO2 : 1.4 Al2O3 : 16 (TMA)2O: 650 H2O. The results demonstrate that there exist good correlation between the crystallisation progress of zeolite A in terms of yield and the attenuated ultrasonic signal. It is also revealed that the kinetic information like activation energy of crystallisation reaction could be easily calculated from the measured ultrasonic signals data. In the studied case, activation energy of Ca. 30 kJ/mol was obtained.

Al-rich mesoporous FSM-16 materials: Synthesis, characterization and catalytic properties

Al-rich mesoporous FSM-16 materials (Si/Al=5–16) have been synthesized using CTMABr as a surfactant. Additional mechanistic insight into the formation of Al-FSM-16 materials is gained from careful characterization of the samples collected at various stages of the preparation procedure by means of XRD and MAS NMR ( 29 Si and 27 Al). These results suggest that the single sheet structure of kanemite breaks up during the intercalation process and regains its structure upon the addition of Na-aluminate and then condensation occurs between the adjacent silicate layers, leading to the formation of mesoporous Al-FSM-16 materials. Fe-exchanged Al-FSM-16 samples were also prepared and their performance tested in the decomposition of N 2 O in a fixed bed reactor.