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• Synthesis of grafted and co-condensated ordered mesoporous materials. • Quantification of the amount of active base sites by liquid phase NMR. • Variation of the properties of the basic centre by changing the substitution on the nitrogen atom. • Determination of the turn-over number in the aldol condensation of butyraldehyde. • Proposed reaction mechanism for heterogeneously catalysed aldol condensation. Representative ordered mesoporous silica materials MCM-41 and SBA-15 were synthesized and modified with nitrogen-containing groups by grafting and co-condensation. The created catalytic centers strongly differ in basicity depending on the degree of substitution of the nitrogen atom. Furthermore, the introduced amount also depends on the structure of the modifier as shown by quantitative liquid phase 1H NMR. This allowed to calculate the turnover number in the aldol condensation of n -butanal which changed in the sequence: secondary > primary >> tertiary >> pyridinic basic centers. Corresponding reaction mechanisms considering the special structural features of the modifier are proposed. ig. [Display omitted] [ABSTRACT FROM AUTHOR]

Adsorption is one of the methods used to reduce free fatty acid in feedstock oils with high acid content that are used for the production of biodiesel. This work investigated MCM-41 synthesized from rice husk silica for the adsorption of oleic acid in isooctane. The adsorption conformed to the Langmuir isotherm model and equilibrium adsorption capacities at 25.0°C were 277.8 mg/g for as- synthesized MCM-41 and 270.3 mg/g for template- removed MCM-41. The determined free energy and enthalpy of adsorption showed that the adsorption was spontaneous and exothermic. Adsorption of oleic acid in soy bean oil was also demonstrated. Results showed that as-synthesized MCM-41 was a better adsorbent than template-removed MCM-41 for oleic acid removal from soybean oil. [ABSTRACT FROM AUTHOR]