A series of solid base catalysts, KF/Ca−Mg−Al hydrotalcite (KF mass ratio of 100%) with different cation ratios, were prepared and studied in this research. Effects of the cation ratio of the Ca−Mg−Al hydrotalcite and the methanol/oil molar ratios on the fatty acid methanol ester (FAME) yield of the transesterification of palm oil with methanol were investigated. The results of the transesterification reactions showed that all of these kinds of catalysts had a very high activity for the biodiesel yields, obtaining 90% or more with 10 min of reaction under the conditions of 338 K, 12:1 methanol/oil molar ratio, and 5% (wt/wt oil) catalyst amount. In addition, the FAME yield could reach 99.6% in 10 min catalyzed by the optimal catalyst KF/Ca−Mg−Al hydrotalcite (2.2:0.8:1 Ca/Mg/Al; KF mass ratio of 100%), under the same reaction conditions as above.
Synthesis of biodiesel from soybean oil over solid base catalyst was investigated in this paper. In process of catalyst preparation, potassium fluoride was used as alkaline metal salt to load onto γ-Al 2 O 3 . Over this basic catalyst, transesterification reactions were carried out to prepare biodiesel using soybean oil and methanol as feedstock. According to experiments, the best reaction conditions were gotten as followed: load ratio was 72.68% (by weight), molar ratio was 12:1 (methanol/oil), reaction temperature was 338 K, mass of catalyst was 2% of oil (by weight), and reaction time was 3 h. Yield of biodiesel exceeds 99%. With X-ray diffraction (XRD) and DSC-TGA characterization, it was proved that new crystal phase synthesized by calcinations showed its favorable effect to the transesterification reaction.
Alkyl esters of long chain fatty acid are called biodiesel. These esters can be obtained from the transesterification of triglycerides with methanol/ethanol. This work investigated the possibility of using KF/γ-Al2O3 as heterogeneous catalysts for the transesterification of cottonseed oil with methanol. The operation variables used were methanol/oil molar ratio (6:1–18:1), catalyst concentration (1–5 wt %), temperature (50–68 °C), and catalyst type. The biodiesel with the best properties was obtained using a methanol/oil molar ratio of 12:1, catalyst (4%), and 65 °C temperature with the catalyst KF/γ-Al2O3. The strongest basic sites (superbasic) promote the transesterification reaction also at very low temperature (65 °C), while the basic sites of medium strength require higher temperatures to promote the same reaction.
This paper discusses the synthesis of biodiesel catalyzed by solid base of K(2)CO(3)/HT using Jatropha curcas oil as feedstock. Mg-Al hydrotalcite was prepared using co-precipitation methods, in which the molar ratio of Mg to Al was 3:1. After calcined at 600 degrees C for 3 h, the Mg-Al hydrotalcite and K(2)CO(3) were ground and mixed according to certain mass ratios, in which some water was added. The mixture was dried at 65 degrees C, and after that it was calcined at 600 degrees C for 3 h. Then, this Mg-Al hydrotalcite loaded with potassium carbonate was obtained and used as catalyst in the experiments. Analyses of XRD and SEM characterizations for catalyst showed the metal oxides formed in the process of calcination brought about excellent catalysis effect. In order to achieve the optimal technical reaction condition, five impact factors were also investigated in the experiments, which were mass ratio, molar ratio, reaction temperature, catalyst amount and reaction time. Under the best condition, the biodiesel yield could reach up to 96%.
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