Kinetic investigation of the aldol condensation of n-butanal on mesoporous and macro-mesoporous heterogeneous catalysts

Abstract

The kinetics of the aldol condensation of n-butanal on modified mesoporous and macro-mesoporous heterogeneous catalysts was studied in the liquid phase. Applying liquid phase 1H NMR the degree of modification was determined quantitatively, in order to calculate the turnover numbers of the n-butanal conversion. The analysis of the kinetic data has shown that the reaction on primary amines follows a 1st order model, whereas on secondary amines the 2nd model gives the best correlation. Tertiary and aromatic amines were not active. Based on the kinetic measurements reaction mechanisms are proposed. The difference in the activation energies suggests that the modification process on mesoporous materials proceeds preferentially on the external surface, while on meso-macroporous materials the modification proceeds in the mesopores.