CN100375780C - Production of biological diesel oil with solid alkali - Google Patents

Abstract

The invention discloses a process for preparing biodiesel by using a solid base catalyst. The process uses a solid base as a catalyst to prepare biodiesel through lipid exchange reaction with short-chain fatty alcohol and vegetable oil at a suitable temperature. The catalyst can be recycled, and the method of combining precipitant and flocculant is used to simply and efficiently remove impurities in crude biodiesel to obtain high-quality biodiesel. The process has the advantages of mild reaction conditions, simple and easy-to-control process, and environmental friendliness, and has good economic benefits.

Description

A kind of technology of utilizing solid alkali to prepare biofuel

Technical field

The present invention relates to a kind of technology of utilizing solid alkali to prepare biofuel, relate in particular to a kind of a kind of heterogeneous catalyst technology of in the transesterification reaction of preparation biofuel, using.

Background technology

Biofuel mainly is to adopt chemical reaction method at present, produce by transesterification reaction, promptly under acidity or basic catalyst and certain temperature, carry out transesterification reaction, generate corresponding Fatty acid methyl ester or second fat with animal-plant oil and methyl alcohol or ethanol, through washing drying, promptly get biofuel again; Simultaneously, obtain by-product glycerin, the Technology of chemical method production biofuel reaches its maturity.

The acid-catalyzed transesterification process is general uses bronsted acid to carry out catalysis.Catalyzer commonly used has the vitriol oil, Phenylsulfonic acid and phosphoric acid etc.Vitriol oil low price, aboundresources, its main problem is: speed of reaction is too slow, long reaction time, the temperature height, and follow side reactions such as sulfonation, sulfation; To the serious corrosion of equipment, and use a large amount of methyl alcohol, make the recovery difficulty of glycerine, thereby this catalyzer is eliminated progressively.

Sodium hydroxide and potassium hydroxide are the catalyzer that adopts in the traditional ester exchange process.The loss of simple employing base-catalyzed transesterification method production fatty acid methyl ester is big, yield is low, and general elder generation adding an acidic catalyst carries out pre-esterification to raw material, adds basic catalyst then and carries out transesterify; Selected not at that time in condition, may take place how much or the secondary reflection of position isomerism, caused yield; Reaction product must be washed, and produces alkali waste in the washing process, if any residual alkali, then generates soap in the diesel oil, easy blocking pipe, and problems such as the generation three wastes cause environmental pollution.

Alkali, alkaline-earth metal alkylate adopt sodium methylate, magnesium ethylate etc. usually, and bibliographical information is all arranged both at home and abroad.Its biggest advantage is the catalytic activity height, but fast reaction speed under the low temperature, and the reaction of need not reducing pressure, catalyzer is soluble in fatty acid ester, but has the shortcoming of homogeneous catalytic reaction equally.

Adopt the homogeneous catalysis method, be difficult to obtain the high-quality methyl esters of high yield, often need neutralize to remove catalyzer the not easily separated purification of by-product glycerol simultaneously.The disadvantage of homogeneous reaction is that aftertreatment is complicated, causes cost to rise, and raw material availability descends, and produces problems such as the three wastes.Therefore, demand the biodiesel manufacture technology of development of new urgently.

Solid super basic catalyst more and more is subjected to numerous investigators' attention with its particular performances.The major advantage of solid super base has: 1. catalytic activity height, reaction conditions gentleness; 2. target product selectivity is good, the product purity height; 3. catalyzer easily separates with product, and technology is simple; 4. catalyzer is reusable, also can use continuously; 5. little to conversion unit corrodibility.

The solid base catalyst that this patent discloses a kind of utilization prepares the technology of biofuel,

Summary of the invention

The object of the present invention is to provide a kind of technology of utilizing solid base catalyst to prepare biofuel; this reaction conditions gentleness, technological process be simple and easy to control, can guarantee to obtain the fine biofuel; catalyzer can be recycled, and has good economic benefits, and environment is not polluted.

Technical scheme of the present invention is as follows:

A kind of preparation method of bio-diesel oil is characterized in that this method carries out as follows:

1) 0.4～9% the solid base catalyst that takes by weighing the vegetables oil weight that intend to drop into is packed in the reaction vessel; This solid base catalyst is made up of alkaline-earth metal and alkali-metal oxide compound, described alkaline-earth metal is one or more among Mg, Ca, Sr and the Ba, described basic metal is one or more among Li, Na, K and the Rb, and wherein the mol ratio of basic metal and alkaline-earth metal is not more than 2/3; Described solid base catalyst is full particle or porous grain type, and wherein porous grain type comprises particle itself that have the porous pattern and with the porous complex body of solid base catalyst attached to the surperficial gained of porous material; This solid base catalyst is a raw material with one or more of alkaline-earth metal and alkali-metal oxyhydroxide, oxide compound, oxysalt and non-oxysalt, by the precipitator method, sol-gel method, support method or the auxiliary synthesis method preparation of template;

2) take by weighing the pure and mild vegetables oil of short-chain fat, join in the reaction vessel, wherein the mol ratio of the pure and mild vegetables oil of short-chain fat is 3.5～12: 1;

3) under whipped state, be heated to 40～90 ℃, after hour reaction of .8～20, stopped reaction;

When 4) treating that temperature is reduced to 30～60 ℃, stir and vacuum state under underpressure distillation recovery short chain fatty alcohol, till vacuum tightness no longer included variation, described vacuum tightness was-0.08～-0.1MPa;

5) product obtains coarse biodiesel and glycerine after solid particulate is removed in centrifugation;

6) impurity in the resulting coarse biodiesel of removing makes biofuel.

Short chain fatty alcohol of the present invention is methyl alcohol, ethanol or their mixture; Described vegetables oil adopts leprosy fruit oil, Oleum Gossypii semen, rapeseed oil, transgenosis rapeseed oil, Viscotrol C, soybean oil, genetically engineered soybean oil, coptis wood oil, shinyleaf yellowhorn oil, Persea cubeba kernel oil, plam oil, sunflower seed oil or peanut oil; The solid particulate that product is removed through centrifugation in the described step 5) uses as catalyst recirculation.

Technical characterictic of the present invention also is: the impurity of removing in the above-mentioned step 6) in the coarse biodiesel adopts settling process and centrifugal separation, or elder generation adds the mixture of precipitation agent, flocculation agent or precipitation agent and flocculation agent, the deionized water that adds oil phase volume 2～50% then mixes the back centrifugation and removes impurity; Described precipitation agent adopts ammoniacal liquor, volatile salt, oxalic acid, citric acid or phosphoric acid, the amount of adding be vegetables oil heavy 0.02～5%; Described flocculation agent adopts contract methylcellulose gum, polyvinyl alcohol, polyacrylamide or polyacrylic acid, the amount of adding be vegetables oil heavy 0.02～5%.

In the process of the impurity in removing coarse biodiesel, when adopting the method for the mixture that adds precipitation agent, flocculation agent or precipitation agent and flocculation agent, the water of adding recycles after centrifugation.

The present invention compared with prior art, have the following advantages and the high-lighting effect: this technology goes for plurality of raw materials, the preparation biofuel productive rate can reach more than 85%.The even phase catalyst that solid alkali can solve available technology adopting as catalyzer is difficult to and the problem of product separation, and the solid alkali of recovery can be used as catalyst recirculation and uses.Adopt precipitation agent and flocculation agent way of combining, simply remove the impurity in the coarse biodiesel efficiently, obtain the fine biofuel.The deionized water that uses when removing the impurity in the coarse biodiesel can recycle.This technology has advantages such as reaction conditions gentleness, technological process be simple and easy to control, environmentally friendly, has good economic benefits.

Embodiment

Solid base catalyst used in the present invention is to be called " a kind of solid base catalyst and preparation method and application " by the applicant in the name of in January, 2005 application (application number: specification sheets 200510011269.0) is described, this solid base catalyst is made up of alkaline-earth metal and alkali-metal oxide compound, described alkaline-earth metal is one or more among Mg, Ca, Sr and the Ba, described basic metal is one or more among Li, Na, K and the Rb, and wherein the mol ratio of basic metal and alkaline-earth metal is not more than 2/3; Described solid base catalyst is full particle or porous grain type, and wherein porous grain type comprises particle itself that have the porous pattern and with the porous complex body of solid base catalyst attached to the surperficial gained of porous material; This solid base catalyst is a raw material with one or more of alkaline-earth metal and alkali-metal oxyhydroxide, oxide compound, oxysalt and non-oxysalt, by the precipitator method, sol-gel method, support method or the auxiliary synthesis method preparation of template (concrete preparation method sees embodiment).

Convenient for the narration of back, represent full particle type solid base catalyst with SX, DK represents the multi-hole type solid base catalyst, and FH represents the porous complex body.When containing a metal ion species, but aperture and specific surface area can add an integer in the back as (1,2,3 when a great difference is arranged ...) etc., to show difference.

The following examples are used to further specify the present invention rather than are used for limiting the present invention.

Embodiment 1:

Under agitation, 7.86 gram calcium nitrate tetrahydrates are dissolved in 400 milliliters of ethanol, continue to stir 30 minutes.200 milliliters of deionization solution that are dissolved with 3.51 gram yellow soda ash are added drop-wise in the above-mentioned solution lentamente, and centrifugation precipitation with deionized water wash precipitation 4 times, places 110 ℃ dry 24 hours of baking oven then.The gained sample promptly obtains full particle type solid alkali SX1 in 1200 ℃ of calcinings 0.5 hour.

19.2 gram methyl alcohol and 85 gram leprosy fruit oil are joined in 500 milliliters the round-bottomed flask putting 1.7 gram SX1 in advance well, install prolong and drying tube, be warming up to 90 ℃ of reactions 2.5 hours, stopped reaction under stirring.When treating that temperature is reduced to 60 ℃, under slowly stirring, methyl alcohol is reclaimed in underpressure distillation under the vacuum tightness of-0.1MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 500 ml beakers, add 2.55 gram citric acids, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyvinyl alcohol of 0.017 gram, stirred 2 minutes, add 1.8 ml deionized water, stirred 10 minutes, solid is removed in centrifugation, obtains biofuel.

Every detection index of the biofuel that makes is listed in subordinate list 1.

Embodiment 2:

Under agitation, 7.86 gram calcium nitrate tetrahydrates are dissolved in 15.72 ml deionized water, continue to stir 60 minutes.200 milliliters of deionization solution that are dissolved with 10.55 gram yellow soda ash are added drop-wise in the above-mentioned solution lentamente, and centrifugation precipitation with deionized water wash precipitation 4 times, places 110 ℃ dry 24 hours of baking oven then.The gained sample promptly obtains full particle type solid alkali SX2 in 700 ℃ of calcinings 10 hours.

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram Viscotrol C are joined in 500 milliliters the round-bottomed flask putting 0.034 gram SX2 in advance well, install prolong and drying tube, be warming up to 40 ℃ of reactions 0.8 hour, stopped reaction under stirring.When maintaining the temperature at 40 ℃, under slowly stirring, methyl alcohol is reclaimed in underpressure distillation under the vacuum tightness of-0.08MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 250 ml beakers, add 1.7 milligrams of oxalic acid, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyacrylamide of 0.42 gram, stirred 2 minutes, add 5.4 ml deionized water, solid is removed in centrifugation, obtains biofuel.

Embodiment 3:

4 gram nitrate of baryta and 4.3 are restrained Magnesium dichloride hexahydrates and join in 600 milliliters of ethanol ultra-sonic dispersion 30 minutes.Under agitation, above-mentioned solution is heated to 60 ℃, adds 200 milliliters of Virahols, succsinic acid 0.8 gram adds XC-72 gac 2.75 grams, and carried out 4 hours at stirring and ultrasonic interval, slowly drip 200 milliliters of the aqueous solution that contain 0.5 gram poly(oxyethylene glycol) 400, continue to stir 4 hours.90 ℃ of following slow solvent evaporated are warming up to 850 ℃ with the speed of 1 ℃/min from 30 ℃, and at 850 ℃ of calcinings 4 hours, multi-hole type solid alkali DK1.

1.12 gram methyl alcohol and 8.5 gram Oleum Gossypii semens are joined in 500 milliliters the round-bottomed flask putting 0.77 gram DK1 in advance well, install prolong and drying tube, be warming up to 75 ℃ of reactions 20 hours, stopped reaction under stirring.When treating that temperature is reduced to 30 ℃, under slowly stirring, methyl alcohol is reclaimed in underpressure distillation under the vacuum tightness of-0.1MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 250 ml beakers, add 0.42 gram citric acid, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyacrylamide of 0.42 gram, stirred 2 minutes, add 5.4 ml deionized water, solid is removed in centrifugation, obtains biofuel.

Embodiment 4:

Under agitation, 0.05 gram hexadecyl trimethyl ammonium bromide is dissolved in 200 milliliters of propyl carbinols of 100 ℃, slowly drips 100 milliliters of the aqueous solution of 0.05 gram polyvinyl alcohol 800, continue to stir 4 hours.The 600 ml water solution that will contain 5.7 gram nitrate of baryta and 4.3 gram Magnesium dichloride hexahydrates slowly are added drop-wise in the above-mentioned system, stir 2 hours.160 ℃ of dryings 24 hours are warming up to 900 ℃ with the speed of 1 ℃/min from 30 ℃ then, and at 900 ℃ of calcinings 4 hours, multi-hole type solid alkali DK2.

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram leprosy fruit oil are joined in 500 milliliters the round-bottomed flask putting 0.51 gram DK2 in advance well, install prolong and drying tube, be warming up to 40 ℃ of reactions 0.8 hour, stopped reaction under stirring.When maintaining the temperature at 40 ℃, under slowly stirring, methyl alcohol and ethanol are reclaimed in underpressure distillation under the vacuum tightness of-0.08MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 250 ml beakers, add 0.017 gram citric acid, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add 1.7 milligrams the methylcellulose gum that contracts, stirred 2 minutes, add 5.4 ml deionized water, solid is removed in centrifugation, obtains biofuel.

Embodiment 5:

Under agitation, with 3.3 gram magnesium chlorides, 2.1 nitrocalcite and 0.5 strontium nitrate are distributed in 120 milliliters of dimethyl formamides, stir to stop after two hours stirring, and 117 milliliters MCM-41 molecular sieve is joined in the above-mentioned system.After 30 minutes, drain solvent under 60 ℃, product obtains porous ABO/ carrier composite material FH1 600 ℃ of calcinings 2 hours

3.6 gram ethanol and 8.5 gram leprosy fruit oil are joined in 500 milliliters the round-bottomed flask putting 0.77 gram FH1 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, ethanol is reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, static 24 hours, solid particulate was deposited on the bottom of flask; Liquid is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 250 ml beakers, add 0.03 gram citric acid, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyacrylic acid of 0.084 gram, stirred 2 minutes, add 3 ml deionized water, solid is removed in centrifugation, obtains biofuel.

Embodiment 6:

5 gram calcium nitrate tetrahydrates and 4.3 gram Magnesium dichloride hexahydrates are joined in 400 milliliters of ethanol ultra-sonic dispersion 30 minutes.Under the vigorous stirring, in above-mentioned solution, slowly drip 20 milliliter of 1,6 hexanediamine, continue to stir 5 minutes, stop to stir, then 85 milliliters ceramic honey comb is joined in the said mixture.Slowly stir 20 minutes after-filtration separate solid products with glass stick,, obtain porous ABO/ carrier composite material FH2 through 800 ℃ of calcinings 3 hours.

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram soybean oil are joined in 500 milliliters the round-bottomed flask putting 0.17 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, methyl alcohol and ethanol are reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 250 ml beakers, add 0.034 gram volatile salt, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add 1.7 milligrams polyacrylic acid, stirred 2 minutes, add 5.4 ml deionized water, solid is removed in centrifugation, obtains biofuel.

Embodiment 7:

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram soybean oil are joined in 500 milliliters the round-bottomed flask putting 0.77 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, methyl alcohol and ethanol are reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, static 36 hours, solid particulate was deposited on the bottom of flask; Liquid is divided into two-layer, and the upper strata is a biofuel, and lower floor is a glycerine.The careful supernatant liquid of drawing obtains biofuel.

Embodiment 8:

3.6 gram ethanol and 8.5 gram Oleum Gossypii semens are joined in 500 milliliters the round-bottomed flask putting 0.34 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, ethanol is reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, to be cooled after room temperature, use supercentrifuge, descended centrifugal 2 hours at 5000 rev/mins.System is divided into three layers, and solid particulate is deposited on the bottom of centrifuge tube; Liquid is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, obtain biofuel.

Embodiment 9:

19.2 gram methyl alcohol and 85 gram coptis wood oils are joined in 500 milliliters the round-bottomed flask putting 1.7 gram SX1 in advance well, install prolong and drying tube, be warming up to 90 ℃ of reactions 2.5 hours, stopped reaction under stirring.When treating that temperature is reduced to 60 ℃, under slowly stirring, methyl alcohol is reclaimed in underpressure distillation under the vacuum tightness of-0.1MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 500 ml beakers, add 2.55 gram citric acids, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyvinyl alcohol of 0.017 gram, stirred 2 minutes, add 1.8 ml deionized water, stirred 10 minutes, solid is removed in centrifugation, obtains biofuel.

Embodiment 10:

19.2 gram methyl alcohol and 85 gram shinyleaf yellowhorn oils are joined in 500 milliliters the round-bottomed flask putting 1.7 gram SX1 in advance well, install prolong and drying tube, be warming up to 90 ℃ of reactions 2.5 hours, stopped reaction under stirring.When treating that temperature is reduced to 60 ℃, under slowly stirring, methyl alcohol is reclaimed in underpressure distillation under the vacuum tightness of-0.1MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 500 ml beakers, add 2.55 gram citric acids, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyvinyl alcohol of 0.01 7 gram, stirred 2 minutes, add 1.8 ml deionized water, stirred 10 minutes, solid is removed in centrifugation, obtains biofuel.

Embodiment 11:

19.2 gram methyl alcohol and the grey daughter nucleus oil of 85 Keshans oil are joined in 500 milliliters the round-bottomed flask putting 1.7 gram SX1 in advance well, install prolong and drying tube, be warming up to 90 ℃ of reactions 2.5 hours, stopped reaction under stirring.When treating that temperature is reduced to 60 ℃, under slowly stirring, methyl alcohol is reclaimed in underpressure distillation under the vacuum tightness of-0.1MPa, till vacuum tightness no longer includes variation.Solid particulate is removed in centrifugation.Liquid in the centrifuge tube is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, place 500 ml beakers, add 2.55 gram citric acids, to stir 10 minutes, precipitation is removed in centrifugation.Draw supernatant liquid, add the polyvinyl alcohol of 0.017 gram, stirred 2 minutes, add 1.8 ml deionized water, stirred 10 minutes, solid is removed in centrifugation, obtains biofuel.

Embodiment 12:

3.6 gram ethanol and 8.5 gram sunflower seed oils are joined in 500 milliliters the round-bottomed flask putting 0.34 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, ethanol is reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, to be cooled after room temperature, use supercentrifuge, descended centrifugal 2 hours at 5000 rev/mins.System is divided into three layers, and solid particulate is deposited on the bottom of centrifuge tube; Liquid is divided into two-layer, and the upper strata is a coarse biodiesel, and lower floor is a glycerine.With the supernatant liquid sucking-off, obtain biofuel.

Embodiment 13:

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram genetically engineered soybean oil are joined in 500 milliliters the round-bottomed flask putting 0.77 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, methyl alcohol and ethanol are reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, static 36 hours, solid particulate was deposited on the bottom of flask; Liquid is divided into two-layer, and the upper strata is a biofuel, and lower floor is a glycerine.The careful supernatant liquid of drawing obtains biofuel.

Embodiment 14:

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram palm fibres are put oil join in 500 milliliters the round-bottomed flask putting 0.77 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, methyl alcohol and ethanol are reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, static 36 hours, solid particulate was deposited on the bottom of flask; Liquid is divided into two-layer, and the upper strata is a biofuel, and lower floor is a glycerine.The careful supernatant liquid of drawing obtains biofuel.

Embodiment 15:

3.2 gram methyl alcohol, 0.72 gram ethanol and 8.5 gram transgenosis rapeseed oils are joined in 500 milliliters the round-bottomed flask putting 0.77 gram FH2 in advance well, install prolong and drying tube, be warming up to 60 ℃ of reactions 9 hours, stopped reaction under stirring.When treating that temperature is reduced to 35 ℃, under slowly stirring, methyl alcohol and ethanol are reclaimed in underpressure distillation under the vacuum tightness of-0.09MPa, till vacuum tightness no longer includes variation.Stop heating, static 36 hours, solid particulate was deposited on the bottom of flask; Liquid is divided into two-layer, and the upper strata is a biofuel, and lower floor is a glycerine.The careful supernatant liquid of drawing obtains biofuel.

The detection index of subordinate list 1 biofuel

Project name	Data unit	The sample of preparation
				Measured value	Method standard
		Density, 20 ℃	g/cm3			0.8784	SH/T?0604
Kinematic viscosity, 20 ℃	mm2/s			7.320	GB/T?265
		Calorific value (height)	Cal/g			9489(35?MJ/L)	GB/T?384
Flash-point (remaining silent)	℃			>170	GB/T?261
		Condensation point	℃			+1	GB/T?3535
Trace carbon residue	％			<0.05	GB/T?17144
		Sulphated ash	％			<0.005	GB/T?2433
S content	mg/L			32(0.0036％)	SH/T?253-92
		Cetane value				56.1	Actual measurement

Annotate: be the data after converting in the bracket.

Claims (6)

1. A method for preparing biodiesel, characterized in that the method is carried out as follows: 1) Take by weighing 0.4 to 9% of the vegetable oil weight to be put into the reaction vessel; the solid alkali catalyst is composed of alkaline earth metals and alkali metal oxides, and the alkaline earth metals are Mg, Ca, One or more of Sr and Ba, the alkali metal is one or more of Li, Na, K and Rb, wherein the molar ratio of alkali metal to alkaline earth metal is not more than 2/3; The solid base catalyst is a solid particle or a porous particle, wherein the porous particle includes a particle with a porous morphology and a porous composite obtained by attaching the solid base catalyst to the surface of the porous material; the solid base catalyst is made of alkaline earth metal and alkali metal One or more of hydroxides, oxides, oxo-acids and non-oxo-acids are used as raw materials, prepared by precipitation method, sol-gel method, loading method or template-assisted synthesis method; 2) Weighing short-chain fatty alcohol and vegetable oil, and adding them into a reaction vessel, wherein the molar ratio of short-chain fatty alcohol and vegetable oil is 3.5 to 12:1; 3) Heating to 40-90°C under stirring, and stopping the reaction after 0.8-20 hours of reaction; 4) When the temperature drops to 30-60°C, the short-chain aliphatic alcohol is recovered by distillation under reduced pressure under stirring and vacuum until the degree of vacuum no longer changes, and the degree of vacuum is -0.08-0.1 MPa; 5) After the product is centrifuged to remove solid particles, crude biodiesel and glycerin are obtained; 6) removing impurities in the obtained crude biodiesel to obtain biodiesel. 2. the method for preparing biodiesel according to claim 1, is characterized in that: described short-chain fatty alcohol is methyl alcohol, ethanol or their mixture. 3. The method for preparing biodiesel according to claim 1, characterized in that: in step 5), the solid particles removed by centrifugation of the product are recycled as catalysts. 4. the method for preparing biodiesel according to claim 1 is characterized in that: described vegetable oil adopts jatropha oil, cottonseed oil, rapeseed oil, transgenic rapeseed oil, castor oil, soybean oil, transgenic soybean oil , Pistacia Oil, Xerifolia Oil, Litsea Cube Kernel Oil, Palm Oil, Sunflower Oil, or Peanut Oil. 5. according to the method for preparing biodiesel described in claim 1,2,3 or 4, it is characterized in that: in described step 6), remove the impurity in crude biodiesel and adopt sedimentation method and centrifugation method, or add earlier Precipitant, flocculant or a mixture of precipitant and flocculant, then add deionized water with an oil phase volume of 2 to 50%, stir and mix evenly, and then centrifuge to remove impurities; the precipitant uses ammonia water, ammonium carbonate, oxalic acid , citric acid or phosphoric acid, the amount added is 0.02% to 5% of the weight of the vegetable oil; the flocculant adopts methyl cellulose, polyvinyl alcohol, polyacrylamide or polyacrylic acid, and the amount added is 0.02% to 5% of the weight of the vegetable oil. 5%. 6. the method for preparing biodiesel according to claim 5 is characterized in that: in the process of removing the impurity in crude biodiesel, when adopting the method for adding the mixture of precipitant, flocculant or precipitant and flocculant, The added water is recycled after being centrifuged.