What is the principle of biodiesel production?
Physical production method of biodiesel:Physical methods include direct mixing method and microemulsion method. Its principle is to plant oil and petrochemical diesel oil and additives, such as the proportion of mixed, but long-term use will lead to carbon deposition and other undesirable effects, so the physical method of production of diesel can not be called qualified biodiesel.
R-COOH R-COOCH3+H2O, the reaction to acid as catalyst, free fatty acid to alkali reaction of soap with alkali as catalyst, namely R-COOH+NaOH (KOH) - R-COOHa (K) +H2O, the reaction system becomes more complex, the soap as emulsifier in the reaction system, the product of glycerol may occur in emulsion and not be separated from the fatty acid methyl ester, water is often alkali catalyst poison water will make the grease generates soap and alkali hydrolysis. Therefore, KOH, NaOH or sodium methoxide (potassium) as the catalyst, often require raw oil acid value is less than 1mgKOH/g, water less than 0.06%. For oil containing water or free fatty acids, two esterification.For free fatty acids with high oil, such as the recovery of waste oil (waste oil, etc.), can be used directly as a catalyst for acid. It is also necessary to limit the water content with acid as catalyst, usually less than 0.5%, because the water will be produced during the esterification of free fatty acid, and the catalytic action of acid catalyst will decrease.
In the absence of water, the transesterification activity of alkaline catalyst is higher than that of acid catalyst. In the traditional production process, the alkali metal hydroxide with higher solubility in methanol was used as homogeneous catalyst. Using KOH as a catalyst for ester exchange reaction of typical conditions are: the amount of methanol is 8%~21%, the dosage of KOH is 0.3%~1%, the reaction temperature is 35~60 DEG C, usually at 60 DEG C to obtain the corresponding reaction reaction rate using NaOH as catalyst.Alkali catalyst can not be used in the case of higher free acid, the presence of free acid poisoning catalyst. Fatty acid methyl ester was produced by esterification of fatty acid with methanol in free fatty acids,
[biodiesel production principle] production methods are physical synthesis and chemical synthesis of two methods,1, chemical synthesis of biodiesel:Chemical synthesis with low carbon alcohols (mainly methanol or ethanol) and transesterification of natural oils, ester exchange obtained after low carbon alcohol esters of long chain fatty acids, molecular weight was reduced to about 300, the relative molecular mass is close to that of diesel, physical and chemical properties similar to diesel fuel, no much difference the performance of diesel. Under mild conditions, the role of the catalyst is very important for transesterification.
