Influence of silica sources on the chemical composition of aluminosilicate hydrogels and the results of their hydrothermal treatment

Krznarić, Ivan; Antonić, Tatjana; Bronić, Josip; Subotić, Boris; Thompson, Robert W. (2003) Influence of silica sources on the chemical composition of aluminosilicate hydrogels and the results of their hydrothermal treatment. Croatica Chemica Acta, 76 (1). pp. 7-17. ISSN 0011-1643

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Abstract

Among the parameters that influence the outcome of a hydrothermal synthesis of molecular sieve zeolites, the effects of various silica sources are some of the least understood. Prior studies have noted that some silica sources were >>active,<< or >> inactive,<< and there have been some suggestions that aluminium impurities can contribute to a silica source's >> activity << to promote certain zeolite syntheses. However, a silica source's activity toward promoting zeolite crystallization has not been definitively shown to be linked to any specific impurity in the silica. This study reports on the use of four different silica sources and the corresponding distribution of Na, Al, and Si between the supernatant and amorphous gel phases. It is shown that the distribution of these species was unaffected by the choice of the silica source, but did vary with batch composition. Furthermore, the degree of silicate polycondensation (DPS), measured by the molybdate method, did not vary with the choice of the silica source. The observed differences in particulate and structural properties of the products crystallized from four different silica sources were analyzed in terms of the critical processes of zeolite crystallization (gel dissolution, nucleation, crystal growth).

Item Type:	Article
Uncontrolled Keywords:	aluminosilicate gels; precipitation; silica source; chemical composition; hydrothermal treatment; zeolite; crystal size; light-scattering spectroscopy; large mordenite crystals; zeolite-a; electron-microscopy; physical-chemistry; crystallization; mechanism; nucleation; gels; precursors
Subjects:	NATURAL SCIENCES > Chemistry
Divisions:	Division of Materials Chemistry
Projects:	Project title Project leader Project code Project type Istraživanje procesa kristalizacije i ionske zamjene zeolita Boris Subotić 00980901 MZOS Istraživanje procesa kristalizacije i primjene zeolita Boris Subotić 0098060 MZOS
Depositing User:	Boris Subotić
Date Deposited:	15 Nov 2013 15:51
URI:	http://fulir.irb.hr/id/eprint/958

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