Different dispersions of group II catalysts over SBA-15 and MCM-41: Effects on transesterification reactivity

• SBA-15 supported catalysts are more active than MCM-41 supported analogues.
• The effect is independent of the nature of the active phase (Ca/Ba).
• It is also independent of the condition of the mesoporous SiO2 and substrate size.
• Ba2 + and Ca2 + active phases are more dispersed on SBA-15 than on MCM-41.

Activities of CaO catalysts on SBA-15 and MCM-41 have been compared in transesterification and SBA-15 supported samples are invariably more active than those on MCM-41. Increased activity is not due to diffusional effects (as measured using substrates of differing size) but rather to increased dispersion of CaO on SBA-15 (as measured using NOx TPD). The effect, i.e. increased reactivity of SBA-15 supported catalysts being related to increased dispersion, is also noted in supported BaO catalysts while supported MgCO3 catalysts show little variation in dispersion (or in reactivity) as a function of the support used.

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