1993 Volume 19 Issue 6 Pages 1060-1066
Vapor-phase aldol condensation and isomerization of butene were studied by use of a eutectic mixture of NaOH-KOH (m.p. 170°C) as the catalyst at 200°C and atmospheric pressure. The activity and stability of the catalyst varied remarkably with supports (activated carbon, alumina, titania, magnesia, silica-alumina) and supporting methods (impregnation method, physical mixing of catalyst with support). Three kinds of decay of catalytic activity were observed. When the catalyst impregnated on activated carbon was used, rates of both reactions decreased with time. In the case of alumina as the support, the rate of isomerization did not decrease with time but the rate of aldol condensation decreased. The rate of aldol condensation did not decrease with time when the catalyst was supported in the vicinity of the surface of activated carbon and silica-alumina. Basic OH- ions, which were formed by melting of the catalyst, were supposed as active species of catalyst for aldol condensation. The surface of these supports with catalyst was observed using a scanning electron microscope, and the interaction between catalyst and supports was investigated.
