The Study Of Preparation Of Biodiesel Using Anion Resin As Catalyst

With the gradual shortage of petroleum resource, biodiesel has been paid much more attention as one of the alternative fuel. Presently, the transesterification reaction of triglyceride which are the leading components of vegetable oil or animal fat with methanol using NaOH or KOH as a homogeneous catalyst is conducted to produce methyl fatty acid ester as biodiesel. Although this process is a mature technology, there are some disadvantages including saponification during the reaction which leads to the difficulty in separation of the production and wastewater from the washing of the production to remove the base catalyst. These problems could be avoided by using the heterogeneous solid catalysts for the production of biodiesel.In this work, we proposed to use a quaternary ammonium poly(phthalazinone ether sulfone)(QAPPES) anion exchange resin/SiO₂ and a quaternary ammonium polysulfone(QAPSF) anion exchange resin/SiO₂ to catalyse the transesterification of soybean oil with methanol to generate methyl fatty acid ester heterogeneously. A series of methyl fatty acid ester as the production could be determinated by gas chromatography/mass spectrometry(GC/MS). From the diagrams of GC/MS, we discovered that the components of the productions catalysed by QAPPES/SiO₂ and QAPSF/SiO₂ had the same retention time and the same form of peaks as the components of the production catalysed by NaOH. The cases had also occurred in simplex gas chromatography(GC) which was used to calculate the conversion rate of methyl fatty acid ester by peak areas. Through GC/MS, the precise components of the production could also be acquired. The three most important components were methyl palmitate(C₁₅H₃₁COOCH₃), methyl linoleate(C₁₇H₃₁COOCH₃) and methyl stearate(C₁₇H₃₅COOCH₃).The influences of reaction included the volume ratio of methanol to oil, the catalyst amount to oil(weight/volume), temperature, reaction time and stirring rate of reaction which were studied and optimized. The best condition were that volume ratio of methanol to oil was 3:1 to 4:1; the catalyst amount to oil(weight/volume) was 1:4 to 3:8; and the temperature was 60℃; fast stirring during the reaction was necessary. After 8h the conversion rate could reach 76% by using QAPPES/SiO₂ and 74 by using QAPSF/SiO₂.The commercial macroporous cross-link resins were also tested as heterogeneous catalysts to catalyze transesterification of soybean oil with methanol. A series of methyl fatty acid ester as the production could also be acquired. The analysis methods of the production catalyzed by D201 and D202 were as the same as the production catalyzed by QAPPES/SiO₂ and QAPSF/SiO₂. The best condition were that volume ratio of methanol to oil was 1:1 to 2:1; the catalyst amount to oil(weight/volume) was 1:4 to 1:2; and the temperature was 60℃. After 6h the conversion rate could reach 80% by using D201 and 81% by using D202.