TY - JOUR

T1 - Effect of temperature and time in the hydrothermal treatment of HY zeolite

AU - Salman, N.

AU - Rüscher, C. H.

AU - Buhl, J. Chr

AU - Lutz, W.

AU - Toufar, H.

AU - Stöcker, M.

PY - 2006/3/20

Y1 - 2006/3/20

N2 - Zeolite HY was steamed at 1 bar water pressure in steps of 100 K from 473 K to 1073 K in dependence of the time (0.5-20 h). Three routes of hydrothermal reactions can be outlined: At low temperature (473 K), a partly framework dissolution occurs accompanied by the formation of X-ray amorphous material. At intermediate temperatures (773-873 K), framework dealumination takes place with the occurrence of different non-framework species. Thereby, with increasing steaming time, saturation of the Si/Al ratio occurs on low levels (Si/Al ratios of about 4 and 5, respectively). At 973 K, a crossover from a low level saturation in Si/Al (6) towards higher values (11) is observed, which is accompanied by a partial amorphization of the zeolite with formation of aluminium oxide and silica gel and a significant decrease in crystal size as well. At high temperatures (1073 K), a fast thermal decomposition occurs. The IR spectra directly reveal an aluminosilicate phase as decomposition product of the framework. At 573 K, the zeolite framework remains unchanged.

AB - Zeolite HY was steamed at 1 bar water pressure in steps of 100 K from 473 K to 1073 K in dependence of the time (0.5-20 h). Three routes of hydrothermal reactions can be outlined: At low temperature (473 K), a partly framework dissolution occurs accompanied by the formation of X-ray amorphous material. At intermediate temperatures (773-873 K), framework dealumination takes place with the occurrence of different non-framework species. Thereby, with increasing steaming time, saturation of the Si/Al ratio occurs on low levels (Si/Al ratios of about 4 and 5, respectively). At 973 K, a crossover from a low level saturation in Si/Al (6) towards higher values (11) is observed, which is accompanied by a partial amorphization of the zeolite with formation of aluminium oxide and silica gel and a significant decrease in crystal size as well. At high temperatures (1073 K), a fast thermal decomposition occurs. The IR spectra directly reveal an aluminosilicate phase as decomposition product of the framework. At 573 K, the zeolite framework remains unchanged.

KW - Amorphization

KW - Dealumination

KW - Steaming

KW - Zeolites

UR - http://www.scopus.com/inward/record.url?scp=32644449025&partnerID=8YFLogxK

U2 - 10.1016/j.micromeso.2005.09.032

DO - 10.1016/j.micromeso.2005.09.032

M3 - Article

AN - SCOPUS:32644449025

VL - 90

SP - 339

EP - 346

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

SN - 1387-1811

IS - 1-3 SPEC. ISS.

ER -