Study of the microstructure of amorphous aluminosilicate gel before and after its hydrothermal treatment

Study of the mechanism of formation of nano-crystalline zeolite X in heterogeneous system

“…The assumption on the existence of the structurally ordered phase in the gel matrix [31] can also be revealed by other methods sensitive to very small fractions of crystalline phase (few cell units) in the gel matrix such as FTIR [35][36][37][38], DTG [32,[37][38][39][40][41] and NMR [41,43,44].…”

“…Taking into consideration earlier studies which showed that thermal analysis is a very sensitive method for the detection of very small structurally ordered units, having a zeolite structure, distributed through the gel matrix [38][39][40][41][42][43], the DTG profiles of both the solid phase (gel) separated from freshly prepared hydrogel (see Fig. 4A) and the crystalline end product (zeolite X; see Fig.…”

A novel synthesis of nano-sized mullite from aluminosilicate precursors

“…The structure of such gels was examined by several methods [21] and especially AFM microscopy showed that they are consisting of three different types of nano-sized entities: (A) near-spheroidalshaped particles (B) "transition", probably partially crystalline, features (particles of "quasi-crystalline" phase and (C) "pyramidalshape" features which look like fully crystalline material. These "pyramidal" shape features are the formed nuclei that depending of the surrounding concentration of Al and Si transform to mullite and SiO 2 .…”

Influence of reaction conditions on the properties of sodium alumino silicate synthesized by simultaneous addition of precursors

“…The vibration at 810 cm − 1 confirms the formation of Si-O-Al bonds [13]. Since IR vibrations of zeolite (crystalline) skeleton are intense for agglomerates of even a few unit cells, the absence of the intense band at 556 cm − 1 (assigned to external vibrations related to D-4 rings in zeolite A framework) reveals that the vibrations observed are for the true amorphous nature of the SAS samples [14].…”