A kind of pre-esterification method for preparing biodiesel

Abstract

A method for preparing biodiesel pre-esterification, using a fixed bed tubular reactor, the middle part of the reactor is a catalyst bed, the upper part is provided with a partition along the axial direction, the lower end of the partition extends into the catalyst bed, and does not completely penetrate the catalyst bed layer, separator and catalyst bed divide the reactor into three parts, the upper feed section and the discharge section are on both sides of the separator, and the lower feed section is below the catalyst bed; tung oil and methanol are fed from the top as feed I The raw material inlet of the feed section enters, methanol and nitrogen enter from the raw material inlet of the lower feed section as feed II, and the feed I undergoes a pre-esterification reaction on the catalyst bed, and the reacted material is combined with the bottom-up feed II Mixing, further reaction, the product is discharged from the discharge port of the discharge section. The reaction mode of the above method makes the material react more fully, improves the conversion rate of the pre-esterification reaction, greatly reduces the acid value of the raw material, and feeds the upper end to reciprocate through the catalyst bed, so that the reaction is more sufficient and the conversion rate of the fatty acid is improved.

Description

technical field [0001] The invention relates to a pre-esterification method for preparing biodiesel, in particular to a pre-esterification method using tung oil with high acid value and methanol as raw materials. Background technique [0002] In the mid-to-late 1980s, as the two major problems of environmental protection and oil resource depletion attracted more and more attention, biodiesel once again became the most popular research topic to solve the energy crisis and environmental pollution. Western developed countries such as the United States, France, and Italy successively A special biodiesel research institution has been established, and a lot of manpower and material resources have been invested in the research of biodiesel. Biodiesel is a non-toxic, biodegradable, renewable clean fuel that can replace ordinary petroleum diesel. It can be mixed with diesel in any proportion or used directly on diesel engines, and can reduce greenhouse gas emissions and reduce air po...

AI Technical Summary

Problems solved by technology

The literature "Study on Pre-esterification of Waste Oil Catalyzed by Solid Composite Acid" and "Research on Preparation of Biodiesel from Oil with High Acid Value" reported the research on the pre-esterification of oil in the tank method. The process is complicated and the conversion rate is low. And it cannot be carried out continuously with the subsequent transesterification reaction, which is not conducive to industrial application

The literature "Research on the Pre-esterification of Tung Oil Catalyzed by Solid Acid" uses ion exchange resin as the catalyst, and the fixed bed continuous reaction method, the acid value is reduced to 0.8KOHmg / g, which has the advantages of fast reaction and continuous performance, but in the process of reaction The water produced in can convert the H in the sulfonic acid group in the catalyst + Carried away, leading to catalyst deactivation and shortening service life

[0005] Chinese patent CN101020863 discloses a pre-esterification process using methanol vapor and grease reaction. Although the acid value can be reduced to 0.5 KOHmg / g, the reaction is still carried out in the reactor, and the amount of methanol vapor is large, and the recovery energy consumption is relatively high. High, not suitable for industrial production; Chinese patent CN103031216A discloses a pre-esterification process for producing biodiesel from waste oil, using concentrated sulfuric acid as a catalyst, which is likely to cause equipment corrosion and environmental pollution

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