Mechanochemistry of zeolites: Part 1. Amorphization of zeolites A and X and synthetic mordenite by ball milling

Synthesis of a forsterite powder by combined ball milling and thermal treatment

“…1 shows that NH 4 -exchanged zeolite A is progressively losing its crystallinity as a function of the milling time t m , and is completely transformed to an X-ray amorphous phase after 5 h of mechanical treatment. This is a much longer time compared to the milling time needed for a sample of pure zeolite NH 4 A (of less than 1 h) obtained in a previous study [14]. The reason of the prolonged milling time needed for the amorphisation is the presence of MgO powder, which is still crystalline even after 5 h of milling.…”

“…The IR spectrum of the starting NH 4 -exchanged zeolite A powder in the mixture contains all the characteristic bands of zeolite A, at 1000, 670, 558, 463 cm −1 (see spectrum labeled a, Fig. 2) [14]. The loss of crystallinity is followed by the decrease of the band at 558 cm −1 and its shifting to 563 and 579 cm −1 , further disappearance of the weak band at 670 cm −1 , and the appearance of a new broad band at 710 cm −1 and a shoulder at 860 cm −1 (see spectra labeled b-e, Fig.…”

“…In the latter case, the amorphisation is caused by the lowering of the crystallite size only [15]. Kinetics of amorphisation of NH 4 -exchanged zeolite A in the mixture are described by the simple exponential equation f a = 1 − exp(−Kt m ) given in [14] (where f a is the fraction of the amorphous phase). The calculation of the kinetic constant K in the case of a mixture with MgO is five times lower than the rate of amorphisation of NH 4 -exchanged zeolite A alone.…”

Electrokinetics of Natural and Mechanically Modified Ripidolite and Beidellite Clays

“…IR spectroscopy has been Samples of ripidolite were prepared for electrophoretic used previously for the determination of structural changes measurements by ultrasonication of a piece of rock. The part during mechanical disintegration experiments of zeolites that disintegrated from the rock (mostly particles of a size (19) and kaolinite (20). Figures 3 and 4 prove that the IR from 8 to 16 mm) was dried at 80ЊC.…”

Microstructural evolution of some MgO–TiO2 and MgO–Al2O3 powder mixtures during high-energy ball milling and post-annealing studied by X-ray diffraction

“…Since the discovery in 1983 that even amorphous alloys can be produced by these techniques [7,8], a new wave of research activity concerned with the possibilities and perspectives of this process has been unleashed. During the past decade we have published the results of our investigations regarding the structural changes in various examined systems induced by ball-mill processing [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In our and in other investigations [25][26][27][28][29] it has been established, that ball milling can facilitate many solid-state reactions, which normally occur only at elevated temperatures and/or high pressure.…”