TY - JOUR
T1 - Hot-spots during the calcination of MCM-41
T2 - a SAXS comparative analysis of a soft mesophase
AU - López Pérez, Lidia
AU - Ortiz-Iniesta, M.J.
AU - Heeres, Hero Jan
AU - Melián-Cabrera, Ignacio
PY - 2014/3/1
Y1 - 2014/3/1
N2 - The phenomenon of microscopic hot-spots, during the calcination of MCM-41, was investigated by quantifying the magnitude of the temperature increase during the calcination of a soft MCM-41 mesophase using a SAXS comparative study. This was performed by thermally treating a soft material that was detemplated via Fenton chemistry followed by equilibrating and drying in a low-surface-tension solvent (n-butanol or N,N-dimethylformamide); these samples have limited structural shrinkage. The resulting samples were thermally treated at increasing temperatures, and the structural shrinkage was compared with that of the directly calcined material. By comparing the structural shrinkage, it was found that the microscopic temperature increase would fall between 190 and 250 C, as deduced from N,N-dimethyl-formamide and n-butanol. The order of magnitude of the temperature increase appears to be consistent with the well-known glow effect. It is, however, substantially higher than the experimentally determined macroscopic temperature increase. Several aspects are discussed to interpret this difference.
AB - The phenomenon of microscopic hot-spots, during the calcination of MCM-41, was investigated by quantifying the magnitude of the temperature increase during the calcination of a soft MCM-41 mesophase using a SAXS comparative study. This was performed by thermally treating a soft material that was detemplated via Fenton chemistry followed by equilibrating and drying in a low-surface-tension solvent (n-butanol or N,N-dimethylformamide); these samples have limited structural shrinkage. The resulting samples were thermally treated at increasing temperatures, and the structural shrinkage was compared with that of the directly calcined material. By comparing the structural shrinkage, it was found that the microscopic temperature increase would fall between 190 and 250 C, as deduced from N,N-dimethyl-formamide and n-butanol. The order of magnitude of the temperature increase appears to be consistent with the well-known glow effect. It is, however, substantially higher than the experimentally determined macroscopic temperature increase. Several aspects are discussed to interpret this difference.
KW - Calcination
KW - Glow effect
KW - Hot-spots
KW - MCM-41
KW - Structural shrinkage
KW - Surfactant-templated mesoporous materials
UR - http://www.scopus.com/inward/record.url?scp=84891717374&partnerID=8YFLogxK
U2 - 10.1016/j.matlet.2013.11.091
DO - 10.1016/j.matlet.2013.11.091
M3 - Article
AN - SCOPUS:84891717374
SN - 0167-577X
VL - 118
SP - 51
EP - 54
JO - Materials Letters
JF - Materials Letters
ER -