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Esterification Reaction of High Free Fatty Acid Content of Crude Palm Oil and Glycerol Using Zinc Glycerolate and Zinc Soap Catalysts

Esterification reaction was carried out to reduce Free Fatty Acid (FFA) content in CPO by converting free fatty acid into a mono-, di- and triglyceride compounds. The raw materials were Crude Palm Oil (CPO) with FFA content of 7.7981 % w/w and glycerol with the minimum purity of 90%. The two types of catalysts used were zinc glycerolate and zinc soap. The difference in their application was that zinc glycerolate was distributed in the glycerol phase while zinc soap was distributed in the oil phase.
The synthesis of zinc glycerolate was conducted by reacting zinc oxide, zinc acetate and glycerol. Whereas zinc soap was zinc compounds which contained medium-chain carboxylic acids. Zinc-glycerolate catalyst was in the form of powder and zinc soap in the form of paste. Both catalysts were characterized by FT-IR. XRD and AAS. The results of catalyst characterization showed that both zinc glycerolate and zinc soap could be used with the high content of zinc as much as 29.4 % w/w and 28.3 % w/w, respectively. Both catalysts were tested in the esterification reaction of free fatty acids and glycerol to determine their activities. Esterification reaction was carried out by feeding all raw materials into a reactor and toluene was added to capture water as a by-product. The reactor was equipped with a set of Clevenger to restore toluene which was condensed back into the reactor. The reaction was carried out at 140 0C for 6 hours with variation of catalyst concentrations (%weight) : 1.2%, 1.4%, 1.6%, 1.8% and 2.0%.
The results showed the optimum reaction occurred when zinc soap catalyst was used with a percentage of 1.2 % w/w at 140 0C for 6 hours. In this condition the FFA content in CPO reduced from 7.7981 % w/w to 0.2036 % w/w.

Keywords : Esterification, free fatty acid, glycerol, zinc glycerolate, zinc zoap

Dikirim oleh: Khairil Amri
KIMIA 2002