CN1699516A - Process for preparing bio-diesel-oil by using microalgae fat - Google Patents

Abstract

The invention discloses a process for preparing bio-diesel-oil by using microalgae fat, which comprises charging a predetermined amount of methyl alcohol into micro-algae grease, heating to a predetermined temperature, at the presence of acid catalyst, producing biological diesel oil through reaction, which has a density of 0.864kg/l, a viscosity of 5.2X10-4 (40 deg. C), and a caloric value of 41MJ/kg.

Description

Utilize microalgae grease to prepare method of bio-diesel oil

Technical field

The invention belongs to biotechnology and energy field, relate to a kind of microalgae grease that utilizes and prepare method of bio-diesel oil.

Background technology

Biofuel is a fatty acid methyl ester, is a kind of biodegradable, nontoxic renewable energy source.Because the exhaustion of petroleum resources and environmental regulation are strengthened, actively develop the development of biofuel and production countries in the world.Since 1988, many European countries just begin the substitute of biofuel as conventional diesel has been used.But because higher material cost makes the price of biofuel be higher than conventional diesel.Therefore choose suitable, cheaply vegetable oil resource to come develop actively and production biofuel be the general trend of development.

Algae has photosynthetic efficiency height, adaptive capacity to environment is strong, growth cycle is short, biological yield is high characteristics, so algae is the good material of preparation bio oil fuel.Heterotrophic growth not only can improve growth efficiency, also helps the accumulation of some meta-bolites such as lipid etc. in the frustule, obtains little algae of high fat content, thereby can reduce the cost of biomass production and grease production.Yet the research of at present relevant biodiesel manufacture all concentrates on aspects such as vegetable oil such as soybean oil, Oleum Helianthi and Semen Brassicae campestris basically, does not see that the heterotrophism microalgae grease prepares the report of biofuel.The most frequently used method of production biofuel is an ester-interchange method, promptly adds a certain amount of methyl alcohol in vegetables oil, is heated to certain temperature, and in catalyzer (acid, alkali or enzyme) effect down, reaction generates fatty acid methyl ester, and isolates the process of byproduct glycerine.This transesterification reaction technology and heterotrophism transformant engineering are integrated, and we have proposed a kind of method of utilizing heterotrophism algae oil and fat preparation high quality biologic diesel oil.Result of study shows, utilizes heterotrophism algae grease can obtain the biofuel suitable with conventional diesel by acid catalyzed transesterification reaction, and its using value is higher.

Summary of the invention

The purpose of this invention is to provide a kind of microalgae grease that utilizes and prepare method of bio-diesel oil, it is characterized in that: described biofuel utilizes microalgae grease to obtain by ester-interchange method; Its preparation process is:

(1) collect little algae, dry then and make algae powder;

(2) utilize the plant oil process from the algae powder, to extract microalgae grease;

(3) transesterification reaction: the adding molar ratio of methanol to oil is 25: 1～84: 1 a methyl alcohol in the microalgae grease, is heated to 30 ℃～90 ℃, and under the sulphuric acid catalysis effect, it is biofuel that reaction generates fatty acid methyl ester, and isolates byproduct glycerine.

The invention has the beneficial effects as follows that 1. utilize microalgae grease can obtain high-quality biofuel through transesterification reaction, its characteristic and traditional fossil diesel fuel are suitable.2. have the good application and the market requirement.

Description of drawings

Fig. 1 (a) is that biodiesel production rate changes synoptic diagram under differing temps and the catalyzer condition (b).

Fig. 2 (a) is the influence synoptic diagram of different molar ratio of methanol to oil to little algae biodiesel production rate and density (b).

Fig. 3 schemes over time for reaction product (biofuel) density under the different molar ratio of methanol to oil conditions.

Embodiment

The invention provides a kind of microalgae grease that utilizes and prepare method of bio-diesel oil.The preparation of its biofuel obtains by ester-interchange method with microalgae grease, and its preparation process is:

(1) collect little algae, dry then and make algae powder;

(2) utilize the plant oil process from the algae powder, to extract microalgae grease;

(3) transesterification reaction: the adding molar ratio of methanol to oil is 25: 1～84: 1 a methyl alcohol in the microalgae grease, be heated to 30 ℃～90 ℃, under the concentrated sulfuric acid catalyst effect, the product that reaction generates is through sherwood oil and water washing, the centrifuging and taking organic phase obtains biofuel with organic solvent evaporation, dry back.It is biofuel that reaction generates fatty acid methyl ester, and isolates byproduct glycerine.

Fig. 1 (a) (b), Fig. 2 (a) is biodiesel production rate and variable density under differing temps and the catalyzer condition (b).By the optimization of transesterification reaction condition, can obtain higher oil yield rate.Utilize microalgae grease to pass through transesterification reaction, can obtain high-quality biofuel.The density of little algae biofuel is 0.864kg l ^-1, viscosity 5.2 * 10 ^-4(40 ℃), calorific value are up to 41MJ kg ^-1These features and conventional diesel are suitable, have good application prospects.

Exemplifying embodiment is below illustrated.

Temperature of reaction that embodiment one is different and catalyst levels are to the influence of little algae biodiesel production rate and density

Reaction conditions is: 30: 1 molar ratio of methanol to oil, shaking speed 160rpm, reaction times 5h.Temperature is respectively 30 ℃, and 50 ℃, 90 ℃; Catalyzer H ₂SO ₄Consumption is 25%, 50%, 60%, 100% (is benchmark with stock oil weight).

Can obtain higher biodiesel production rate under 50 ℃ of conditions, more low-density biofuel then all obtains down at 90 ℃.Under identical temperature condition, catalyst levels is that 100% o'clock of stock oil can obtain more low-density biofuel.The biofuel of least density (0.862) then is to obtain under 90 ℃, catalyst levels are 100% condition of stock oil.

At catalyst levels is under 100% condition of stock oil, and productive rate and density when 30 ℃ and 50 ℃ do not have very big difference.Biodiesel production rate under 30 ℃ and 50 ℃ of conditions is respectively 56% and 58%, and the density of the biofuel under 30 ℃ and 50 ℃ of conditions was respectively for 0.878 and 0.875 (as shown in Figure 1).Therefore consider from the angle that reduces cost that the reaction conditions of the acid-catalyzed transesterification reaction of microalgae grease is that 30 ℃, the catalyst levels of 100% raw material oil mass are comparatively suitable.

The different molar ratio of methanol to oil of embodiment two is to the influence of little algae biodiesel production rate and density

Reaction conditions is: 30 ℃ of temperature, shaking speed 160rpm, catalyzer H ₂SO ₄Consumption is 100% (is benchmark with stock oil weight), reaction times 7h.

Contrasting the influence of six kinds of different molar ratio of methanol to oil to product ratio and density thereof, be 45: 1 and can obtain the biofuel of higher yields at 56: 1 o'clock at molar ratio of methanol to oil, is respectively 68% and 63%.Under these two kinds of molar ratio of methanol to oil conditions, not only obtain the biofuel of higher yields, and obtained low-density biofuel.At molar ratio of methanol to oil is that the density of the biofuel that obtains of 45: 1 and 56: 1 o'clock is respectively 0.873 and 0.864.Molar ratio of methanol to oil is also to obtain the biofuel (as shown in Figure 2) than low density (0.878) at 30: 1 o'clock.

Reaction product (biofuel) density under the embodiment three different molar ratio of methanol to oil conditions over time

Reaction conditions is: 30 ℃ of temperature, shaking speed 160rpm, catalyzer H ₂SO ₄Consumption is 100% (is benchmark with stock oil weight)

Molar ratio of methanol to oil is that the density of the biofuel that obtains of 25: 1,70: 1 and 84: 1 o'clock is higher, and methanol usage makes troubles for separation subsequently when too big.The density of biofuel product is all along with the prolongation in reaction times is downward trend gradually under the molar ratio of methanol to oil condition of these 30: 1,45: 1 and 56: 1.But molar ratio of methanol to oil is 56: 1 o'clock, and the density of biofuel product dropped to lower-most point in 4 hours shortest times, has obtained density and be 0.864 biofuel; And molar ratio of methanol to oil is 30: 1 and 45: 1 o'clock, needs 5-7 hour its product density just to be tending towards minimum (as shown in Figure 3).

Above experimental result shows, the optimum reaction condition of the acid-catalyzed transesterification reaction of microalgae grease should be 30 ℃, the catalyst levels of 100% raw material oil mass and 56: 1 molar ratio of methanol to oil; With this understanding, can obtain density in 4 hours is 0.864 high-quality biofuel.

Claims (1)

1. one kind is utilized microalgae grease to prepare method of bio-diesel oil, it is characterized in that: described biofuel utilizes microalgae grease to obtain by ester-interchange method; Its preparation process is:

(1) collect little algae, dry then and make algae powder;

(2) utilize the plant oil process from the algae powder, to extract microalgae grease;

(3) transesterification reaction: the adding molar ratio of methanol to oil is 25: 1～84: 1 a methyl alcohol in the microalgae grease, is heated to 30 ℃～90 ℃, and under the sulphuric acid catalysis effect, it is biofuel that reaction generates fatty acid methyl ester, and isolates byproduct glycerine.

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