A kinetic study of the thermal degradation of cetyltrimethylammonium bromide inside the mesoporous SBA-3 molecular sieve

Abstract

Thermal degradation of cetyltrimethylammonium bromide (CTMAB) inside the mesoporous SBA-3 has been studied under non-isothermal conditions. There are two distinct although partly overlapping kinetic processes, and both of them can be described by the Sestak-Berggren model. The main decomposition step proceeds with E(a) = 116 +/- 2 kJ/mol which is significantly lower than for the mesoporous MCM-41 and MCM-48 suggesting that the interaction between CTMAB and the silica network plays a crucial role in the removal of the surfactant from the as-synthesized material. The second decomposition step has a higher E(a) value (E(a) = 153 +/- 5 kJ/mol) than the first step, indicating that it is primarily controlled by the size of the pore openings.