Catalytic reactions by thermally activated, synthetic, anionic clay minerals

Major advances have been made towards dcsign, realization, and optimization of efficient catalytic systems based on modified aluminosilicate mincrals.

Catalysis of organic reactions by inorganic solids

Organic reactions on alumina

The complete oxidation of acetone has been studied over a series of manganese oxide catalysts supported on the unpillared and the Al- and Zr-pillared forms of two natural clays of the smectite class (a montmorillonite and a saponite). The temperatures required for total combustion of acetone over the several catalysts ranged from 610 to 660 K at the relatively low W Mn / F in ratio of 0.40 g Mn  min mmol acetone −1 used. A significant influence of the clay supports characteristics on the catalytic performance has been found. According to the general behaviour of the various catalysts throughout the light-off tests, the following order of improving catalytic performance can be established with respect to the pillars composition: Al-pillared clays 2 O 3 , MnO 2 , Al 2 O 3 and ZrO 2 , as well as physical mixtures of ZrO 2 with the unpillared clays. The effect on the catalytic performance of the possible competition between the acetone combustion and aldol condensation processes has also been considered.

Complete oxidation of acetone over manganese oxide catalysts supported on alumina- and zirconia-pillared clays

The aldol condensation of lower aldehydes over MFI zeolites with different acidic properties

Carbon-13 nuclear magnetic resonance studies of the aldol condensation products of acetone on an activated alumina catalyst

Conventional 13C nuclear magnetic resonance spectroscopy is used to monitor the reactions of butan-2-one and pentan-3-one adsorbed on alumina. Both reaction sequences proceed via successive aldol condensations. The products observed for butan-2-one (5-methyl-4-hepten-3-one and 4-hydroxy-4-methylpentan-2-one) are those expected for homogeneous base catalysis. A J-modulated spin–echo sequence demonstrates that 5-ethyl-4-methyl-5-hepten-3-one, the β, γ condensation product, is obtained using pentan-3-one. The results demonstrate that conventional 13C n.m.r. can be effectively used to distinguish reaction pathways and products for surface-catalysed reactions.

Valerie A. Bell

Papers

Carbon-13 nuclear magnetic resonance studies of the aldol condensation products of acetone on an activated alumina catalyst

Aldol condensation of butan-2-one and pentan-3-one on an activated alumina as monitored via in-situ carbon-13 nuclear magnetic resonance spectroscopy