The Application Of Sodium Phosphate In The Biodiesel Synthesized From Waste Restaurant Grease

As the improvement of living standards and increasing of waste cooking oil in the catering sector, the reasonable disposition and the utilization of waste cooking oil have attracted much attention. At present, a technology of recycling waste material has been put into actual production that waste cooking oil was used to produce biodiesels. But such a kind of industries that both energy and environmental protection were restricted by many factors. Catalyst is the key factor and is very important role in the whole process of the preparation. It has an impact on preparation condition, process and production rate of biodiesel. In the use of traditional catalysts for biodiesel production process, because of the catalyst and product separation difficulties in post processing, a large amount of waste liquid to emissions, eventually lead to the increasing of production cost in the whole technology.This article adopts the cleaning technology in the process, and waste cooking oil was used to prepare biodiesel through chemical method. In the guarantee of objective product yield to find a suitable catalyst that has many advantages compared with the old ones, such as low cost, no acidic waste water in the preparation process and so on. In the paper, compared to acid catalyst and alkali catalyst shows that the advantages of the use of sodium phosphate as a catalyst is not only the amount of catalyst is low, but aslo short reaction time and high efficiency. The main conclusions of the experiments were as follows:(1) Free fatty acid of waste cooking oil was transesterified with to its methyl esters with methanol by ferric sulfate as catalyst. The best esterification process condition were as follows:the molar ratio of methanol to oil was8:1, the catalyst amount was2.0g,60℃reaction temperature, and reaction time was4h. The acid value waste restaurant grease can be reduced to less than0.8615mgKOH/g using acid catalyzed, that is the esterification rate of free fatty acid was76.95%.(2) Catalyst activity of sodium phosphate (Na3PO4) was tested via waste cooking oil transesterification with methanol to produce biodiesel. The optimal parameters of esterification obtained by onhonormal experiment were as follows:the molar ratio of methanol to oil was10:1, the catalyst amount was1.2g, reaction temperature was70℃, and reaction time was3h. The acid value waste restaurant grease can be reduced to less than0.82mgKOH/g using alkaline catalyzed, that is the esterification rate of free fatty acid was80.12%.(3) Comparative study of two catalysts esterified biodiesel effects and its composition analyzed by gas chromatography. For comparison with other materials resulting biodiesel, final results showed that:The main component of fatty acid methyl ester from waste cooking oil are methyl cetylate, methy linoleate and methyloleateby gas chromatography. For comparison with other materials resulting biodiesel, final results showed that:The results showed that the main component of fatty acid methyl ester from waste cooking oil, methyl palmitate, methyl linoleate, methyl oleate, methyl linolenate and stearyl acid methyl ester which the amounts are17.83%,35.21%,13.61%,15.36%,11.95%, respectively. The components of the produced biodiesel are similar to that produced from plant oil, and can meet the requirement of diesel substitute.