Method for continuously producing biodiesel by using two segments of fixed beds

Abstract

The invention relates to a method for continuously producing aliphatic ester type biodiesel by adopting two segments of fixed bed reactors by taking animal grease and plant grease or waste grease as a raw material. The method comprises the following steps: mixing the raw material grease with lower alcohol like methanol or ethanol, and allowing the mixture to successively pass through two fixed bed reactors which are connected in series and filled with a solid catalyst; performing an ester exchange reaction and an esterification reaction in the first reactor, separating glycerinum generated in the reaction from the mixture flowing out from the first reactor, then replenishing the lower alcohol into the second reactor for the esterification reaction, and separating the lower alcohol and glycerinum from the mixture flowing out from the second reactor to obtain the aliphatic ester type biodiesel. Through the method disclosed by the invention, the two reactors can be selectively filled with a solid acid catalyst or a solid alkali catalyst according to the quality of the raw material grease, and a glycerinum byproduct is removed in midway of the reaction so as to break chemical balance, so that efficient conversion of the raw material grease is realized, the production efficiency is improved, and a high-purity glycerinum byproduct can be produced.

Description

technical field [0001] The invention relates to the technical field of biochemical new energy, in particular to a process for continuously producing fatty acid ester biodiesel by using double fixed beds connected in series and using animal and vegetable oils or waste oils as raw materials. Background technique [0002] Due to the increasing shortage of petrochemical energy and the resulting environmental problems, countries around the world have accelerated the development of renewable clean energy. Among them, biodiesel is a good alternative to fossil fuels. Biodiesel is a long-chain fatty acid low-alkane monoester produced by esterification or transesterification with low-carbon alcohols from animal and vegetable oils or waste oils. CO, NO emissions from burning biodiesel compared to fossil diesel x And the amount of particulate dust is greatly reduced. In addition, compared with fossil diesel, its high lubricity, high cetane number, and high flash point all make it a g...

AI Technical Summary

Problems solved by technology

Under the action of a homogeneous base catalyst, the transesterification can be carried out relatively completely at a relatively low temperature (40-65°C) and in a short period of time. However, this process has the following disadvantages: first, when the reaction is completed, the catalyst It will remain in the reaction product. At this time, it is necessary to use acid to neutralize and then use a large amount of water to remove the homogeneous base. This process not only makes the catalyst unable to be recycled, but also produces waste water that will bring greater follow-up treatment costs. ; In addition, because glycerol is miscible with water, the introduction of a large amount of water will bring difficulties to the subsequent purification of glycerol

The transesterification reaction is a reversible reaction, which will be affected by thermodynamic limitations in a single-stage reactor, and fatty acid glycerides cannot be completely converted