No abstract

No abstract

Esterification reaction between glycerol and lauric acid in the presence of STA/MCM-41 and H2SO4 catalysts indicated that the activity of synthesized catalyst had been comparable to H2SO4. On the other hand, only di glyceride formation instead of favored mono glyceride has been observed with H2SO4 which had rendered the use of heterogeneous STA/MCM-41 catalyst preferable. Temperature had a decreasing effect on lauric acid conversion due to competitive adsorption of water on catalyst structure. The high mono glyceride selectivity obtained in favor of the desired product was due to shape selectivity of the catalyst. High glycerol amount in feed ratio resulted in deformation of long range order of the catalyst structure and hence a decrease in mono glyceride selectivity. Experiments conducted in identical conditions in the presence of recovered catalysts showed a decrease in lauric acid conversion which had been due to loss of STA from catalyst structure.

In this study, firstly the synthesis of acidic catalysts was carried out by loading the active compound silicotungstic acid(STA) with dry (W/Si:10-50%) and wet (W/Si:10%) impregnation methods into MCM-41 support material. These synthesized catalysts were used in the production of mono-di and tri laurin. The amount of active substance in the synthesized catalysts was determined by the ratios of tungsten in STA and silicon in MCM-41 structure. Moreover, W/Si: 10% by weight of STA was applied to the support material after the calcination process was loaded by dry impregnation method. Brønsted acid (BA) and Lewis acid (LA) regions of synthesized catalysts were determined by DRIFT analysis. The catalytic activities of the catalysts were determined by a glycerollauric acid esterification reaction in a batch reactor. The effect of calcination and active compound ratio with reaction temperature on the lauric acid conversion and mono-di and tri laurin selectivity was investigated. Furthermore, the esterification reaction of glycerol with lauric acid was carried out under the same conditions in the presence of a commercial catalyst Amberlyst-21. The experimental results of the synthesized catalysts and Amberlyst-21catalyst were compared. The synthesized catalysts after comparison were observed that have high catalytic activity. Lauric acid conversion and monolaurin selectivity have been obtained with W/Si: 10% catalyst (dry impregnation method) 3/3/1 molar ratio at383K after 6 hours 95% and 88%, respectively. XRD analysis was conducted on calcineduncalcined MCM-41support material. Moreover, the structural properties of synthesized catalysts after the esterification reaction were determined by SEM-MAPPING analysis methods.

In the present study, the synthesis of SBA-15 (Santa Barbara Amorphous) support material(SPm) was initially carried out with the method determined according to the literature research. The catalytic property of SBA-15 was imparted by the hydrothermal method (HtM), different from the traditionally applied impregnation method. In this method, the active substance (iron III oxide; Fe2O3) was added to the solution during the synthesis of the SPm. The amount of active substance in the synthesized catalysts was calculated based on the mass ratios of silicon (Si) in SBA-15 and iron (Fe) in Fe2O3. The active substance ratios in the catalysts were determined as 10, 25% Fe/Si. The activities of Fe/SBA-15 catalysts were tested in methyl acetate production (MAP). MAP reaction experiments were carried out in the presence of 0.4g catalyst (Fe/SBA-15), 373K, in autogenous pressure and 2/1 Acetic acid(AA)/methanol(MeOH) feed rate for 48 hours. The effects of active substance loading rate on AA conversion were determined. The structural properties of Fe/SBA-15 catalysts were investigated by XRD, BET, FTIR/DRIFT, SEM/EDX, and MAPPING analysis methods.