A method for stably preparing biodiesel

Abstract

The present invention proposes a method for stably preparing biodiesel, comprising: (1) making low acid value grease, monohydric alcohol and metal carboxylate catalyst contact reaction, separating biodiesel from product, and reclaiming catalyst; (2) when step ( 1) When the decline in the yield of biodiesel exceeds the tolerance value, the recovered carboxylate catalyst is added to the system in which low acid value oil and monohydric alcohol exist, and C 1 -C 24 Carboxylic acid or oil with high acid value is reacted at a reaction temperature of 100-200°C and a pressure of 0.1-3MPa. The method of the invention can rapidly increase the activity of the catalyst at a lower reaction temperature and pressure, the deactivated catalyst can be regenerated in situ, and the product yield can exceed the initial yield.

Description

Technical field [0001] The present invention relates to a method of preparing biodiesel by an oil and a monohydric alcohol. Background technique [0002] The biodiesel can be prepared by the ester exchange reaction of the oil and a monohydric alcohol, and there is a fatty acid monoalkyl ester (i.e., biodiesel), and monoglycerides, bisglycerides, glycerol, and unreacted alcohols and fats (ie Triglyceride). The preparation method of biodiesel in the prior art can be divided into acid catalytic, base catalytic, enzyme catalysis and supercritical. [0003] The CN1473907A uses the underwind and edible recovery oil of vegetable oil, and the catalyst is made of sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, dodecyl benzenesulfonic acid, naphthalene sulfonic acid, etc., is acidified and is acidified , Continuous dehydration, esterification, layering, decompression distillation, etc., continuous vacuum dehydration pressure is 0.08-0.09MPa, temperature 60-95 ° C, dehydration to ...

AI Technical Summary

Problems solved by technology

The shortcomings of using enzyme catalysts are: long reaction time, low efficiency, high cost of enzyme catalysts, and easy deactivation in high-purity methanol

This method can reduce the reaction temperature to 100-200 °C and the pressure to 0.1-2 MPa, and the carboxylate catalyst is a solid catalyst, which is easy to separate from the product, and the post-treatment process is simplified, but the carboxylate catalyst is used for low acid value When preparing biodiesel from oil, the activity of the catalyst decreases rapidly. Usually, when the raw oil treatment capacity per gram of catalyst reaches 100-200 grams, the yield of biodiesel will drop significantly