Details
| Original language | English |
|---|---|
| Pages (from-to) | 3-9 |
| Number of pages | 7 |
| Journal | Reaction Kinetics and Catalysis Letters |
| Volume | 76 |
| Issue number | 1 |
| Publication status | Published - May 2002 |
Abstract
The reaction behavior of sodium chloride sodalite Na8[AlSiO4]6Cl2 in ammonium chloride solution has been investigated under mild hydrothermal conditions (T = 473 K) for reaction times up to 72 h. Reactions under weak acid conditions led to an amorphous aluminosilicate phase comparable to a leaching process. This material forms an amorphous layer around the sodalite grains, preventing the framework from further decomposition. About 52% of sodalite was damaged by acid leaching after 11 hours and this amount remains nearly constant even at longer reaction periods up to 72 hours. Cation exchange was observed in sodalite only on a very low level (< 10%). Beside these reactions under acid conditions (pH ≈ 5) some additional experiments in alkaline solutions were done to improve ion exchange of sodalite. Thus an ammonium/ammonia buffer solution was used (pH ≈ 9) at various temperatures in a range of 353 - 473 K. Neither cation exchange nor decomposition of the sodalite was obtained at 353 and 393 K after 72 hours. Formation of amorphous material started at 433 K. In contrast to the acid conditions a total transformation of sodalite into a crystalline ammonium aluminosilicate phase was observed at 473 K.
Keywords
- Acid leaching, Cation exchange, MAS NMR, Phase transformations, Sodalites
ASJC Scopus subject areas
- Chemical Engineering(all)
- Catalysis
- Chemistry(all)
- Physical and Theoretical Chemistry
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In: Reaction Kinetics and Catalysis Letters, Vol. 76, No. 1, 05.2002, p. 3-9.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Kinetics and phase transformations during the reaction of NaCl-sodalite in ammonium chloride solutions
AU - Buhl, Josef Christian
AU - Pietsch, Hans Henning
AU - Fechtelkord, Michael
PY - 2002/5
Y1 - 2002/5
N2 - The reaction behavior of sodium chloride sodalite Na8[AlSiO4]6Cl2 in ammonium chloride solution has been investigated under mild hydrothermal conditions (T = 473 K) for reaction times up to 72 h. Reactions under weak acid conditions led to an amorphous aluminosilicate phase comparable to a leaching process. This material forms an amorphous layer around the sodalite grains, preventing the framework from further decomposition. About 52% of sodalite was damaged by acid leaching after 11 hours and this amount remains nearly constant even at longer reaction periods up to 72 hours. Cation exchange was observed in sodalite only on a very low level (< 10%). Beside these reactions under acid conditions (pH ≈ 5) some additional experiments in alkaline solutions were done to improve ion exchange of sodalite. Thus an ammonium/ammonia buffer solution was used (pH ≈ 9) at various temperatures in a range of 353 - 473 K. Neither cation exchange nor decomposition of the sodalite was obtained at 353 and 393 K after 72 hours. Formation of amorphous material started at 433 K. In contrast to the acid conditions a total transformation of sodalite into a crystalline ammonium aluminosilicate phase was observed at 473 K.
AB - The reaction behavior of sodium chloride sodalite Na8[AlSiO4]6Cl2 in ammonium chloride solution has been investigated under mild hydrothermal conditions (T = 473 K) for reaction times up to 72 h. Reactions under weak acid conditions led to an amorphous aluminosilicate phase comparable to a leaching process. This material forms an amorphous layer around the sodalite grains, preventing the framework from further decomposition. About 52% of sodalite was damaged by acid leaching after 11 hours and this amount remains nearly constant even at longer reaction periods up to 72 hours. Cation exchange was observed in sodalite only on a very low level (< 10%). Beside these reactions under acid conditions (pH ≈ 5) some additional experiments in alkaline solutions were done to improve ion exchange of sodalite. Thus an ammonium/ammonia buffer solution was used (pH ≈ 9) at various temperatures in a range of 353 - 473 K. Neither cation exchange nor decomposition of the sodalite was obtained at 353 and 393 K after 72 hours. Formation of amorphous material started at 433 K. In contrast to the acid conditions a total transformation of sodalite into a crystalline ammonium aluminosilicate phase was observed at 473 K.
KW - Acid leaching
KW - Cation exchange
KW - MAS NMR
KW - Phase transformations
KW - Sodalites
UR - http://www.scopus.com/inward/record.url?scp=0036431847&partnerID=8YFLogxK
U2 - 10.1023/A:1015668707761
DO - 10.1023/A:1015668707761
M3 - Article
AN - SCOPUS:0036431847
VL - 76
SP - 3
EP - 9
JO - Reaction Kinetics and Catalysis Letters
JF - Reaction Kinetics and Catalysis Letters
SN - 0133-1736
IS - 1
ER -