CN101289627B - Process for reducing acid value of biodiesel - Google Patents

Abstract

A method for reducing the acid value of biodiesel oil is characterized in that: rectification of crude fatty acid methyl ester or fatty acid ethyl ester is carried out; a deacidification agent occupying 0.02 to 4 percent of the total weight of fine fatty acid methyl ester or fatty acid ethyl ester is added after the rectification; the mixture is gradually heated up to 60 to 80 DEG C inside a stirring reaction kettle, and is put in a settling tank when the stirring reaction is carried out for 0.2 to 0.5 hours; after 2-hour settlement, the lower-layer deacidification agent is discharged; the acid value of an upper layer is measured, and the upper layer is put in a finished product tank after the acid value is up to standard; and the deacidification agent can be used repeatedly. The method is simple and does not need complex equipment; meanwhile, the method has low production cost and ideal deacidification effect, and the diesel oil manufactured by the method accords with national standard; the separated deacidification agent can be used repeatedly to produce naphthenic acid amide which is a chemical raw material and can increase the economic benefits of a biodiesel oil enterprise. Tests and a standard method adopted to measure the acid value of biodiesel oil before and after deacidification show that the acid value of biodiesel oil can be reduced more than 90 percent when deacidified through adopting the method.

Description

A kind of method that reduces acid number of biodiesel

One, technical field

The present invention relates to a kind of method that reduces acid number in the biofuel.

Two, background technology

Minimizing year by year along with the mineral diesel storage capacity, reproducible bioenergy is all being sought by various countries, because fatty acid methyl ester is the most approaching at aspect such as combustionproperty, characteristic and mineral diesel, therefore, it is the raw material production biofuel that developed countries such as America and Europe all develop with the vegetables oil.

China also has the people to carry out the work in this respect, as Chinese patent application 92114795.3, does the Catalyst Production biofuel with natural fats and oils by alkali, and acid number can be up to standard, but can't produce use because of cost of material is high; Chinese patent application CN 1473907A, with reclaiming high acid value lipid acid production biofuel in the waste material, acid number also can only reach 4.5mgKOH/g, does not reach national BD100 standard; Chinese patent application CN 1031070C, adopt acid to carry out pre-esterification for catalyzer, after reaction is finished, add in the pure and mild excess base again and an acidic catalyst and residual free fatty acids, residue alkali is as the production technique of transesterification reaction, but, adopt above-mentioned two-step approach catalysts consumption to increase, double process period, facility investment is big, energy consumption significantly rises, and in addition, needs basic catalyst is removed from product, have and contain the alkali waste water generation in a large number, contaminate environment reclaims the glycerine difficulty, and production cost is too high.

Three, summary of the invention

The technical problem to be solved in the present invention is: provide a kind of and reduce the method for acid number of biodiesel by adding acid lowering agent, make the biofuel of producing meet national standard, thereby solve high acid value biofuel etching problem to body in engine.

Solving the technical scheme that problem of the present invention takes is: with acid number is that crude fatty acid methyl ester or the fatty-acid ethyl ester of 1-5mgKOH/g carries out rectifying, after rectifying, add the acid lowering agent that accounts for smart fatty acid methyl ester or fatty-acid ethyl ester gross weight 0.02～4%, in stirred autoclave, be warming up under 60～80 ℃ gradually, stirring reaction was put into slurry tank in 0.2～0.5 hour, sedimentation separated in 2 hours emits lower floor's acid lowering agent, acid number is measured on the upper strata, is put into the finished product jar after qualified; Described acid lowering agent is thanomin, diethanolamine, trolamine, preferred trolamine; Isolated acid lowering agent can be reused.

Positively effect of the present invention is: method is simple, does not need complex apparatus, and production cost is low; It is effective to fall acid, uses the inventive method depickling artifact diesel oil acid number can reduce more than 90%, and the diesel oil of production meets national standard; Isolated acid lowering agent can be reused, and it is cycloalkanoimide that acid lowering agent repeatedly uses its product of back, and it is a kind of industrial chemicals, can increase the biofuel economic benefit of enterprises.

Four, embodiment

Embodiment one:

In 5L stirring reaction container, add biofuel 2Kg, its acid number is 2.1mgKOH/g, and acid lowering agent is a trolamine, with 0.056Kg, acid lowering agent divides three addings, and stir speed (S.S.) is 300rpm, heat temperature raising to 75 ℃, reacted 0.5 hour, sampling after cooling, measured reaction artifact diesel oil acid number is 0.176mgKOH/g, sour extrusion rate is 91.6%.

Embodiment two:

In 5L stirring reaction container, add biofuel 2Kg, its acid number is 2.1mgKOH/g, and acid lowering agent is the sediment among the embodiment one, once adds, stir speed (S.S.) is 300rpm, heat temperature raising to 75 ℃ reacted 0.5 hour, and the back sampling cools, measured reaction artifact diesel oil acid number is 0.52mgKOH/g, and sour extrusion rate is 75.2%.

Embodiment three:

In 5L stirring reaction container, add biofuel 2Kg, its acid number is 2.1mgKOH/g, and acid lowering agent is a thanomin, with the 0.056Kg acid lowering agent, divide three times and add, stir speed (S.S.) is 300rpm, heat temperature raising to 75 ℃, reacted 0.5 hour, cool behind the back sampling measured reaction, acid number of biodiesel is 0.29mgKOH/g, and sour extrusion rate is 86.2%.

Embodiment four:

In 5L stirring reaction container, add biofuel 2Kg, its acid number is 2.1mgKOH/g, acid lowering agent is embodiment three sediments, once adds, and stir speed (S.S.) is 300rpm, heat temperature raising to 75 ℃, reacted 0.5 hour, the back sampling measured reaction artifact diesel oil acid number that cools is 0.77mgKOH/g, and sour extrusion rate is 63.4%.

Embodiment five:

In 5L stirring reaction container, add biofuel 2Kg, its acid number is 2.1mgKOH/g, and acid lowering agent is a diethanolamine, divides three addings with the 0.056Kg acid lowering agent, stir speed (S.S.) is 300rpm, heat temperature raising to 75 ℃ reacted 0.5 hour, behind the back sampling measured reaction that cools, acid number of biodiesel is 0.21mgKOH/g, and sour extrusion rate is 90%.

Embodiment six:

In 5L stirring reaction container, add biofuel 2Kg, its acid number is 2.1mgKOH/g, acid lowering agent is embodiment five sediments, once adds, and stir speed (S.S.) is 300rpm, heat temperature raising to 75 ℃, reacted 0.5 hour, the back sampling measured reaction artifact diesel oil acid number that cools is 0.62mgKOH/g, and sour extrusion rate is 70.5%.

Use the inventive method, naphthenic acid and acid lowering agent generation chemical reaction that free fatty acids in the biofuel and acid catalysis are produced, the cycloalkanoimide that generates is nontoxic, so the acid lowering agent of small residue need not to remove fully from biofuel in the biofuel, exist in the biofuel, do not influence biofuel character, also have certain corrosion inhibition.It is cycloalkanoimide that acid lowering agent repeatedly uses its product of back, and it is a kind of industrial chemicals, can increase the biofuel economic benefit of enterprises.

Through test of many times, adopt standard method to measure the acid number of depickling front and back biofuel, prove and use the inventive method depickling artifact diesel oil acid number to reduce more than 90%.

Claims (1)

1. method that reduces acid number of biodiesel, it is characterized in that: with acid number is that crude fatty acid methyl ester or the fatty-acid ethyl ester of 1-5mgKOH/g carries out rectifying, after rectifying, add the acid lowering agent that accounts for smart fatty acid methyl ester or fatty-acid ethyl ester gross weight 0.02～4%, in stirred autoclave, be warming up under 60～80 ℃ gradually, stirring reaction was put into slurry tank in 0.2～0.5 hour, sedimentation 2 hours separates emits lower floor's acid lowering agent, and acid number is measured on the upper strata, is put into the finished product jar after qualified; Described acid lowering agent is a trolamine; Contain acid lowering agent in the sediment, can reuse.