The aim of the research was the study of aluminium-magnesium hydrotalcite by FTIR analysis and detection of differences in structure due to calcination. Three types of samples were analysed. In the fi rst two samples, cobalt was added into the structure and the third sample contained nickel and zinc. Hydrotalcite was prepared by one of the most common methods of hydrotalcite preparation, co-precipitation. After preparation, the samples were calcined at temperatures from 150 °C to 750 °C. Samples were compared in terms of calcination temperature; but in case of samples containing cobalt, two samples to each other. The most signifi cant changes were noticed in the 500-700 cm -1 region, where a spinel structure was formed at higher calcination temperatures.
This paper is focused on the heterogeneously
catalyzed transesterification
(in a batch reactor) of vegetable oil, including the determination
of leached metals. The oil was obtained from the short-season crop Camelina sativa. The reaction was catalyzed by mixed
oxides, which were synthesized from Mg/Al hydrotalcites with built-in
different types of divalent cations such as Mn, Ca, Co, Ni, and Fe.
The various physicochemical properties like the structure by X-ray
diffraction, acidity, basicity, and textural properties were measured
and the effect of the added cation type on catalyst properties and
activity was compared. A noticeable relationship between the cation
type and catalytic activity in the transesterification reaction was
observed. The highest ester content of 96.6 wt % after 7 h of transesterification
was observed for catalysts with nickel and iron. The statistical analysis
of results showed that the catalyst activity was mainly influenced
by middle-temperature basic sites. The novelty lies in transesterification
over five different heterogeneous catalystsmixed oxides with
added divalent metals at the same reaction conditions of C. sativa oil.
The aim of the research was to prepare and characterize hydrotalcite synthesized under different preparation conditions. The most common hydrotalcite preparation is the co-precipiaton method. The preparation process strongly influences the catalytic properties of hydrotalcite; therefore, optimal conditions have to be determined. During the study, seven samples of the catalyst were prepared in the pH range from 8 to 12 and the synthesis temperature range from 25 to 55 °C. Based on several catalyst properties, optimal synthesis pH 10 was found. Ideal temperature of the preparation was determined to be 35 °C, but the temperature does not have a significant effect on the catalyst properties.
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