Time-resolved neutron diffraction analyses of hydrothermal syntheses using a novel autoclave cell

Abstract

An autoclave cell has been designed for performing time‐resolved neutron diffraction analyses of the dynamic processes occurring during hydrothermal syntheses under hostile (corrosive and explosive) conditions: such conditions include those of hot NaOH/NaOD solutions and pressurized steam. The cell is also capable of measuring differential pressures and accurate sample temperatures as required for the study of reactions which are temperature sensitive. The cell is described and examples of its successful use are given illustrating the synthesis of basic zeolites and a layered calcium silicate hydrate. This technique has considerable potential for studying a variety of synthesis processes of industrial importance, such as in the production of catalysts and the hydration of cements.

In‐situ‐Verfolgung der Bildung kristalliner Feststoffe

“…[34] 2. [35] der hydrothermalen Bildung von Zeolithen und Schichtsilicaten, [36] der temperaturabhängigen Kristallisation von ZrO 2 aus Zr-Hydroxiden [37] und der druckabhängigen Bildung von Metallhydriden verwendet. [38] Analog zu SAXS werden mit der Neutronenkleinwinkelstreuung (SANS) Partikel im Größenbereich von etwa 1 bis 100 nm untersucht.…”

Time- and space-resolved dynamic studies on ceramic and cementitious materials

“…Neutrons retain an advantage if specimen-bulk averaging is required whereas penetrating X-radiation is preferable when combined time/ space-resolution is required. Since the ®rst in situ EDD study of autoclave synthesis (Polak et al, 1990;Munn et al, 1992;He et al, 1992), energetic synchrotron radiation has been increasingly used to penetrate specimen cells made of metal (steel, aluminium) or polymer (PEEK) and designed to withstand autoclave conditions, typically 403 to 523 K (more spectacular examples of bulk specimen penetration are presented in x5). Such methodology has now become near-routine and is particularly well subscribed to in the ®eld of synthesis of microporous materials (e.g.…”

Time-Resolved in Situ Synchrotron X-ray Diffraction Studies of Type 1 Silicon Clathrate Formation

“…Here we have exploited recently-developed in situ synchrotron X-ray diffraction techniques to obtain time-resolved structural data during the course of clathrate synthesis reaction. In earlier work of this kind, where tailor-made environmental cells were necessary to deliver highly specialized conditions to the sample, in situ data collection was more conveniently carried out by exploiting the adaptability of either white beam energy-dispersive X-ray diffraction 34 or neutron diffraction 35 techniques.…”