Method for preparing biodiesel with low sulfur content from gutter oil

Abstract

The invention discloses a method for preparing biodiesel with low sulfur content from gutter oil. The method comprises a series of procedures as follows: pretreatment, esterification reaction, vacuum impurity removal, transesterification, glycerin separation and dealcholization as well as distillation refining. According to the technology, sulfur-containing substances are not introduced into the whole technological process except raw gutter oil materials in production while concentrated sulfuric acid is commonly used as a catalyst in the esterification reaction in the prior art; the vacuum impurity removal process is added before the transesterification process, impurities (including sulfur-containing impurities) with low boiling point are removed in advance, so that the sulfur content of a product is further reduced, and content of ester is increased.

Description

technical field [0001] The invention belongs to the technical field of biodiesel preparation, and in particular relates to a method for preparing low-sulfur diesel from waste oil. Background technique [0002] Due to the increasing depletion of non-renewable energy sources on the earth, people have begun to look for alternatives to traditional energy sources. At this time, biodiesel, as a new type of energy that is renewable and has less impact on the environment than traditional fossils, came into people's field of vision. However, the cost of traditional biodiesel production is relatively high, because the raw materials for traditional biodiesel production are oil crops (such as rapeseed, soybean, sunflower seeds, etc.). This has hindered the promotion of biodiesel, so scientists put forward the idea of ​​using gutter oil to turn waste into treasure. The common methods for preparing gutter oil are acidification, alkalization, enzymatic and supercritical transesterificatio...

AI Technical Summary

Problems solved by technology

Through the continuous change of the solvent phase, the reactants, products, and wastes are exchanged in the fluid, and finally the purification of the products and the notes on the wastes and by-products are realized, which greatly reduces the environmental burden. The only problem is that this technology is due to the ditch The composition of the oil itself is extremely complex, so it is still difficult to implement

[0004] Because gutter oil contains more water and free fatty acids, and the process of acid catalysis is the simplest, acid catalysis is often used in the production of biodiesel at present. Concentrated sulfuric acid is used as a catalyst for the preparation of oils with more water and free fatty acids. Diesel oil has a relatively high yield, but a large amount of waste sulfuric acid will be produced during the production process, and the direct discharge of waste sulfuric acid will cause pollution, and the use of lye to neutralize will increase the cost. Pollution to the environment after use