Method for separating and purifying biodiesel

Abstract

The invention discloses a method for separating and purifying biodiesel. The method comprises the steps of: 1) performing degassing and distillation operation on a crude biodiesl product by a film evaporator to obtain the biodiesl of which the content of methyl ester is over 96 percent; and 2) performing alkaline soil deacidification on a product of separation treatment in the step 1) to obtain purified biodiesel of which an acid value satisfies the national standard. By the method, alkaline solution is absorbed on the surface of alkaline soil for a deacidification reaction, which effectively avoids emulsification; the method has simple operation conditions, does not need to strictly control conditions such as stirring and the like; components such as glycerol and soap can be absorbed after the reaction is finished; the obtained methyl ester does not need to be purified again, does not need to be dehydrated, is easy to separate, and has high yield; and a purified product has high quality. The method has the advantages of simple process flow, low equipment cost and energy consumption, and no wastewater pollution, and is suitable to be popularized and applied in a large area.

Description

Technical field [0001] The invention relates to a method for separating and purifying biodiesel in the field of biochemical industry. Background technique [0002] Biodiesel is a clean fuel refined from renewable resources (such as rape oil, soybean oil, recycled cooking oil, etc.). As a new type of renewable energy, biodiesel has the characteristics of being environmentally friendly and alternative to diesel, and has been extensively studied and applied worldwide. At present, biodiesel is mainly produced by chemical methods, using vegetable oil and methanol or ethanol in an acid or alkaline catalyst and an esterification reaction at 230-250°C to generate the corresponding fatty acid methyl or ethyl biodiesel. Nowadays, researchers are still studying the technology of bio-enzymatic synthesis of biodiesel. Research results show that lipase is a good catalyst for the transesterification of alcohol and fatty acid glycerides. As a kind of biocatalyst, enzyme has high catalytic effi...

AI Technical Summary

Problems solved by technology

At present, the production process adopted by most domestic manufacturers of biodiesel has the problems of long production cycle, low product purity, low recovery rate, high cost and serious pollution

In terms of quality and environmental protection, it does not meet the European emission IV and other standards. The fatty acid methyl ester content of biodiesel reaches more than 98% and the requirements of pollutant emission limits. Therefore, it cannot be used as an alternative energy source for high-end cars, and can only be limited to industrial boilers and agricultural use. Industries with relatively low requirements such as machinery; on the other hand, from a cost perspective, high equipment and energy costs coupled with low completion rates make the market less competitive

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