Vapor phase butanal condensation was studied over unsupported and supported alkaline earth oxides including: MgO, MgO/SiO2, SrO/SiO2, MgO-SrO/SiO2 and MgO/HY. NH3-TPD illustrated that new acid sites were generated when the alkaline metal oxides were supported on silica. As compared to the un-supported MgO, the silica supported MgO, SrO and MgO-SrO and MgO/HY exhibited an almost five times higher activity, a higher stability and an improved selectivity to 2-ethyl-2-hexenal. This indicates that both acid and base sites are needed to achieve good catalytic performance for gas phase aldol condensation reactions. Catalyst activation and deactivation mechanisms were studied by butanal TPD-DRIFTS and Butanoic acid TPD-TGA. At temperatures below 300oC all catalysts deactivated due to poisoning by the butanoic acid, which was produced as a byproduct. The weak bonding of the adsorbed species on the MgO/SiO2 surface contributed to the improved stability of the catalyst for vapor phase butanal condensation.

Butanal self-condensation over un/supported alkaline earth metal oxides: Catalyst activation and deactivation mechanisms

243rd National Meeting (2012)

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