Esterification and ester interchange reaction method of biodiesel

Abstract

The invention discloses an esterification and ester interchange reaction method of biodiesel. The method is characterized in that methanol is heated and pressurized by a methanol gasifier, the gasification temperature of 84-220 DEG C and the pressure of 0.2-5.5 MPa make methanol be in a near subcritical state, and the obtained methanol gas is injected to a reaction tower in the above state from the bottom of the reaction tower through adopting a porous pipeline; raw material oil is preheated to 80-120 DEG C through a heater, and the preheated oil is sprinkled to the reaction tower at a certain flow velocity from the top end of the reaction tower; and the temperature of 84-220 DEG C and the pressure of 0.2-5.5 MPa in the reaction tower are kept and controlled, and allow methanol to be in a subcritical state and make the raw material oil be miscible with methanol, so a two-phase chemical reaction under routine reaction conditions becomes a single-phase chemical reaction in order to solve the interphase mass transfer problem. The method has the advantages of fast reaction speed, high esterification and ester interchange efficiency, and no addition of catalysts in the reaction process.

Description

Technical field [0001] The invention belongs to the technical field of biodiesel production, and specifically relates to a method for esterification and transesterification of biodiesel. Background technique [0002] Biodiesel refers to fatty acid monoalkyl esters obtained by transesterification of animal and vegetable oils and alcohols (methanol or ethanol), the most typical being fatty acid methyl esters. Compared with traditional petrochemical energy, its sulfur and aromatics content is low, the flash point is high, the cetane number is high, and it has good lubricity. It can be partially added to petrochemical diesel, so biodiesel is a real green diesel. [0003] At present, the methods for industrialized production of biodiesel include chemical synthesis and bioenzyme synthesis. The chemical synthesis of biodiesel uses oil and methanol or ethanol and other low-carbon alcohols, and uses acidic or alkaline catalysts for esterification or transesterification. , Generate the corr...

AI Technical Summary

Problems solved by technology

However, chemical synthesis of biodiesel has the following disadvantages: the reaction temperature is high and the process is complicated; excessive methanol is used in the reaction process, and the subsequent process must have a corresponding alcohol recovery device, the treatment process is complicated, and the energy consumption is high; Free fatty acids will seriously affect the yield and quality of biodiesel; the purification of products is complicated, and the esterification products are difficult to recover; the by-products generated by the reaction are difficult to remove, and the use of acid and alkali catalysts produces a large amount of waste water, and the discharge of waste acids and lyes is easy to harm the environment cause secondary pollution

However, there are still some problems to be solved urgently in the preparation of biodiesel by biological enzyme method: lipase is effective for the esterification or transesterification of long-chain fatty alcohols, but the conversion rate of short-chain fatty alcohols (such as methanol or ethanol, etc.) is low, Generally only 40% to 60%; methanol and ethanol have certain toxicity to enzymes, which are easy to inactivate enzymes; by-product glycerol and water are difficult to recover, not only for product formation, but also glycerol is toxic to enzymes; short-chain fats The presence of alcohol and glycerol affects the reactivity and stability of the enzyme, greatly shortening the service life of the immobilized enzyme

The inventive method has a certain limitation on the acid value range of the raw material oil, and is not suitable for the raw material oil with an acid value less than 50mgKOH / g, and the reaction pressure and temperature are relatively high, and the reaction time is relatively long