Catalytic distillation production method for biodiesel

Abstract

The invention provides a method for continuously producing biodiesel. The method comprises the following specific steps of: preheating grease and a low-carbon alcohol according to a certain proportion, and pumping into a catalytic distillation tower filled with a solid acid or a basic catalyst; feeding the grease from the upper part of the tower in a liquid form; feeding the low-carbon ethanol from the lower part of the tower in a steam form; inversely contacting the grease and the low-carbon ethanol; performing an esterification or ester exchange reaction on a solid acid or alkali catalyst bed layer in the tower; condensing the low-carbon alcohol evaporated on the top and making a part reflow to the tower top; circularly using the remaining part; and treating a bottom discharged material by using a sedimentation laminating device to obtain biodiesel from an upper layer and side product glycerol from a lower layer. A catalytic distillation process based on a solid acid or alkali catalyst is adopted, and reaction and separation processes are integrated, so that the consumption of a large quantity of low-carbon alcohols is lowered, and the yield of biodiesel is up to 99 percent; the solid acid or alkali catalyst can be used repeatedly; and the method for producing biodiesel has the advantages of energy saving, environmental friendliness, suitability for continuous scale production, and good market prospect.

Description

technical field [0001] The invention relates to a method for continuously preparing biodiesel, in particular to a method for producing biodiesel by catalytic rectification based on a solid acid or alkali catalyst, and belongs to the technical field of biodiesel preparation. Background technique [0002] Biodiesel is a kind of potential green renewable energy. Its performance is similar to that of petrochemical diesel, but it is superior to petrochemical diesel in terms of sulfur content, flash point, cetane number and clean combustion. It can be compared with petrochemical diesel at any Proportional mixing to prepare biodiesel blended fuel. [0003] In order to reduce the cost of biodiesel and expand the source of raw materials for biodiesel, various oils such as soybean oil, rapeseed oil, palm oil, lard, swill oil, gutter oil and frying waste oil can be used as raw materials. Alcohol esterification or transesterification and separation process to produce biodiesel. [000...

AI Technical Summary

Problems solved by technology

CN102206552A discloses a method for preparing biodiesel by vapor-liquid-solid heterogeneous catalysis. The solid acid catalyst is packed in the reaction tower, the lower part of the tower is fed with low-carbon alcohol vapor, and the upper part is sprayed with liquid fatty acid. Esterification reaction occurs, although the conversion rate of fatty acid is high (98%) in this method, but because only the esterification process of fatty acid is involved, the raw material source of biodiesel is greatly limited

CN1861752A discloses a method for producing biodiesel by using waste oil with high acid value, using solid iron trichloride to catalyze the esterification reaction between free fatty acid in waste oil and low-carbon alcohol, and then washing and removing ferric chloride with low-carbon alcohol , and then use sodium hydroxide and potassium hydroxide to convert the pre-esterified residual oil into biodiesel through transesterification. Although this method adopts the pre-esterification process and expands the source of raw materials, a homogeneous alkali is still required in the later stage of the reaction. Catalysis, which will inevitably bring problems such as wastewater treatment and environmental pollution

[0005] In the traditional biodiesel production process, there are still problems of excessive methanol consumption and high energy consumption in the separation process

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