CN102453732B

CN102453732B - Method for preparing fuel ethanol from fermentable sugars in fresh straw juice

Info

Publication number: CN102453732B
Application number: CN201010513906.5A
Authority: CN
Inventors: 张全; 黎元生; 佟明友; 王鑫
Original assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Current assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Priority date: 2010-10-14
Filing date: 2010-10-14
Publication date: 2014-05-21
Anticipated expiration: 2030-10-14
Also published as: CN102453732A

Abstract

The invention discloses a method for preparing fuel ethanol from fermentable sugars in a fresh straw juice. The method comprises the following steps: 1, collecting fresh straws, juicing them, and carrying out solid-liquid separation to obtain a straw juice and straw residue; 2, concentrating the straw juice until the total content of fermentable monosaccharides is 20-24%; 3, adjusting the concentrated straw juice to be in a state suitable for fermentation; and 4, adding ethanol fermentation strains, fermenting to obtain a fermentation mash, and further separating to recover ethanol. The method of the invention, which overcomes a problem that the fermentable sugars are difficult to obtain in the ethanol production process with cellulose in dry corn straws as a raw material, has the advantages of high production efficiency, suitableness of the large scale industrialization production, and the like.

Description

Utilize fermentable sugars in fresh straw juice to prepare the method for alcohol fuel

Technical field

The present invention relates to a kind of production method of alcohol fuel, be specially the method for the fresh fuel ethanol produced by straw that a kind of utilization contains fermentable sugars.

Technical background

Along with mineral fuel is day by day exhausted, oil price is high, and greenhouse gas emission causes global warming, and based on the needs of Sustainable development, national governments pay much attention to the development of alcohol fuel.

China attaches great importance to energy diversification and problem of environmental pollution, takes the incentives such as fiscal subsidy and deductions and exemptions of tax, carries forward vigorously technology and the industry development of the diversification petroleum replacing energy.The appearance of " Renewable Energy Law " and National Program for Medium-to Long-term Scientific and Technological Development, has greatly advanced the development process of the biological liquid fuel such as biofuel and alcohol fuel.China is planned for the year two thousand twenty, biofuel consumption accounts for 15% left and right of whole traffic fuel, set up the biofuel industry with international competitiveness, this has brought good opportunity to develop (to make widely known strong to China's fuel ethanol industrial, to Weida, Zhou Tao etc. China's alcohol fuel current situation and trend analysis. analysis expert, 2009,31 (1) :).Do not strive the problem of grain with people in order to solve alcohol fuel, in recent years, lignocellulose, particularly maize straw are prepared Fuel Ethanol and in worldwide, are caused research and development upsurge.

In maize straw butt, contain Mierocrystalline cellulose 30%-40%, hemicellulose 20%-30%, can utilize production alcohol fuel.CN200910022106.0 provides a kind of prozyme of producing reducing sugar by degrading maize straws, utilizes every gram of stalk butt of this prozyme can obtain reducing sugar 480mg.CN200910204295.3 provides the high temperature resistant S. cervisiae FE-B of a strain and the application in stalk simultaneous saccharification and fermentation production ethanol process thereof, and by batch charging, final solid content reaches under 40% condition, and the alcohol concn in system can reach more than 8%.Utilize the principle of the cellulose raw producing and ethanol in maize straw simple, fibre substrate produces reducing sugar after acid hydrolysis or Enzymatic hydrolysis, then utilizes yeast or fermentation using bacteria to produce ethanol, still has many problem demanding prompt solutions but will realize industrialization.(1) Mierocrystalline cellulose in maize straw is wrapped up by hemicellulose and xylogen, and there is complicated crystalline structure, be unfavorable for the degraded of cellulase, therefore need developing low-cost and high efficiency maize straw preconditioning technique, the advance of preconditioning technique directly affects total sugar yield and Financial cost.(2) tie up the production cost of plain enzyme and zytase too high, also restricted the process of industrialization of cellulose raw producing and ethanol process in maize straw.(3) high-level efficiency of pentose fermentation conversion is the another bottleneck of realizing cellulosic industrialization.Pentose is the hemicellulose Nulomoline in maize straw, pentose can not be become ethanol by common yeast fermentation, the yeast that some energy xylose-fermentings that current many research institutions all exist by means of occurring in nature are ethanol, such as candiyeast, pipe capsule yeast, pichia spp etc.But sugar alcohol transformation efficiency is generally lower, therefore need to utilize gene engineering method to build the yeast strain that can efficiently utilize hexose and pentose simultaneously.(4) carry out pretreated saccharic acid separation problem with sulfuric acid.(5) problem of becoming sour in cellulase hydrolysis process.(6) restraining effect of by product to Yeast engineering bacteria such as furfural etc. in cellulosic hydrolysate.CN200610054545.6 provides a kind of method of utilizing cornstalk juice to prepare beverage.Also do not utilize up till now stalk of fresh corn to prepare the report of alcohol fuel.

Summary of the invention

The present invention produces the object of alcohol fuel in order to realize non-grain raw material, overcome the above-mentioned Mierocrystalline cellulose that utilizes in maize straw butt and obtain difficult problem for fermentable sugars in raw material production ethanol process, propose a kind of production efficiency higher, be applicable to the method for the fermentable sugars ethanol production in the use fresh corn straw juice of large-scale industrialized production.

The present invention utilizes fermentable sugars in fresh straw juice to prepare the method following (percentage composition is by weight) of alcohol fuel:

1, collect fresh straw, squeeze the juice and carry out solid-liquid separation, obtain straw juice and stalk slag, in straw juice, contain sucrose 0-12%, glucose 0-8%, fructose 0-8%, being converted to the monosaccharide concentration of always can fermenting is 2%-18%.

2, above-mentioned straw juice is concentrated, the monose total content that makes to ferment is 20%-30%, is preferably 20%-24%;

3, concentrated straw juice is adjusted to the state of suitable fermentation;

4, add ethanol fermentation bacterial strain, fermentation obtains karusen, and further Separation and Recovery ethanol.

In the inventive method, stalk can be maize straw, preferably after harvest corn, in 60 days, collects and squeezes the juice, and most preferably in 10 days, collects and squeezes the juice.In maize straw, straw juice generally can account for the 30%-90% of total fresh corn stalk weight.The stalk slag obtaining can further adopt solid fermentation method by the residual fermentable sugars acquisition ethanol that further ferments.

In the inventive method, the concentrated method of straw juice can be multiple-effect vacuum evaporation, thin film evaporation or nanofiltration membrane separation etc., preferably multiple-effect vacuum evaporation.

In the inventive method, the state that concentrated straw juice is adjusted to suitable fermentation mainly comprises and adds bacterial strain to produce required nitrogenous source, then regulates pH value.Nitrogenous source can be yeast extract paste, urea or ammonium sulfate etc., preferably urea, and nitrogenous source add-on is 001%-0.1% by weight.Regulate the general sulfuric acid that adopts of pH value, pH is generally 4.5-4.8.Carry out carrying out fermenting process after sterilising treatment.

In the inventive method, the bacterial strain ethanol fermentation bacterial strain arbitrarily that fermentation adopts, bacterium and/or the yeast of sucrose, glucose and the fructose production ethanol of can fermenting all can use, bacterium and/or the yeast of access can be bought lyophilized powder from the market, also can after the seed culture tank of factory floor is cultivated voluntarily, transfer.Ethanol fermentation process condition is also well known to those skilled in the art, and temperature is generally 28-36 ℃, and fermentation time is generally 24-48h.The separation of ethanol recovery that fermentation obtains karusen can adopt any existing method, as distillation concentrate, ultrasonic wave concentrate etc.

Utilize maize straw to produce alcohol fuel and only utilize at present Mierocrystalline cellulose and hemicellulose wherein, the sugar containing in maize straw is less, generally be unwell to production alcohol fuel, these sugars generally stalk deposit in process or Mierocrystalline cellulose preprocessing process in decompose.But still under jejune precondition, in order to develop non-grain alcohol fuel, adopt suitable technological process in cellulose ethanol production technology, utilize the fermentable sugars producing fuel ethyl alcohol by ferment in fresh corn straw juice to become a kind of feasible selection.In the juice of corn fresh straw, contain certain fermentable saccharide, comprise sucrose, fructose and glucose, can be generated ethanol by common yeast fermentation easily, by suitable art breading, can be for the production of alcohol fuel.

Major advantage of the present invention: the one, with the replacement of the fermentable sugars in the discarded situation traditionally food crop production ethanol in fresh corn stalk, save grain, reduce production cost; The 2nd, utilize Mierocrystalline cellulose in maize straw butt to produce on the basis of alcohol fuel in research and development, preferentially utilize the fermentable sugars that is more easily fermented generation ethanol in fresh straw juice to produce alcohol fuel, for processing and the recycling of maize straw provide more economic worths, the solution difficult problem that grain is produced ethanol by no means simultaneously; The 3rd, production technology process is simple, production cost is low, is conducive to apply.

Embodiment

Describe the detailed process of the inventive method below in detail.

1. harvesting corn stalk in 60 days after harvest corn, removes fringe, root and the leaf of fresh straw, obtains clean fresh corn stalk.

2. the clean fresh corn stalk juice extractor that step 1 obtains is squeezed the juice, and obtains fresh corn straw juice (accounting for the 30%-90% of total fresh corn stalk weight) and fresh corn stalk slag (accounting for the 10%-70% of total fresh corn stalk weight).

3. in the fresh corn straw juice obtaining in step 2, contain sucrose 0-12%, glucose 0-8%, fructose 0-8%, being converted to the monosaccharide concentration of always can fermenting is 2%-18%.Adopt all available concentration method that do not destroy the monose total amount of can fermenting in juice to make the fermented monose total amount in juice be concentrated to 20%-24%, as multiple-effect vacuum evaporation, thin film evaporation and nanofiltration membrane separation etc., the preferred multiple-effect vacuum evaporation of the present invention.

4. the concentrated fresh corn straw juice obtaining in step 3 is driven in fermentor tank, add the required nitrogenous source of appropriate yeast growth, nitrogenous source in substratum of the present invention can be yeast extract paste, urea and ammonium sulfate etc., preferably urea, urea add-on is 0.01%-0.1%, and utilizing 10% sulphur acid for adjusting pH is 4.5-4.8, then adopts universal method in the industry to carry out sterilizing to the material in fermentor tank.

5. in step 4, in the material of sterilizing, access ethanol fermentation bacterial strain, can be bacterium and/or the yeast that all existing or unknown fermented sucrose, glucose and fructose are produced ethanol, bacterium and/or the yeast of access can be bought lyophilized powder from the market, also can after cultivating voluntarily, the seed culture tank of factory floor transfer, preferably saccharomyces cerevisiae FE-B of the present invention is ethanol fermentation bacterial strain, cultivate voluntarily rear switching by seed culture tank, inoculum size is 0.05%-0.15%.

6. the temperature of controlling in the postvaccinal fermentor tank of step 5 is 28-36 ℃, intermittent stirring, and fermentation 24-48h, obtains karusen.

7. karusen is distilled in rectifying tower, obtain ethanol.

8. in the fresh corn stalk slag that step 2 obtains, also contain the maize straw juice of total stalk total amount 5%-25%, can take the method for solid state fermentation is ethanol to this part fermentable sugars fermentation.Maize straw slag is added after the urea of 0.01%-0.05%, mix, sterilizing, then adds the yeast of 0.05%-0.15%, mix, be deposited into can the aseptic room of heat and moisture preserving in, carry out solid state fermentation, fermentation time is 24-72h, after fermentation ends, solid fermented material is carried out to vacuum-drying, and the steam producing in drying process is incorporated into step 7 rectifying workshop section, and rectifying obtains ethanol.

Fermentable sugars concentration in embodiment 1 fresh straw sampling analysis juice

On October 16th, 2009, label was No. 1 sample and No. 2 samples respectively from the each fresh corn stalk that gathers about 15kg in He Shangsi village of mill disc village of Fushun City of Liaoning Province periphery.Fetch rear defoliation, be cut into segment and put with preservative film parcel, for subsequent use in-20 ℃ of Refrigerator stores, No. 1 sample and No. 2 samples have been carried out respectively to water content, glucose, fructose and sucrose content analysis.

No. 1 sample

Get at random the freezing fresh stalk of 30 joints, thaw, peeling.Medullary substance portion (1#-M) and the skin zone (1#-S) of fresh stalk weigh respectively, measure respectively water content after pulverizing, and sugared content in water.Glu, Fru and Suc represent respectively glucose, fructose and sucrose, the results are shown in Table 1.

Water content, glucose, fructose and sucrose content in No. 1 sample of table 1

	Gross weight g	Water content %	Pol	Glu％	Fru％	Suc％	Total reducing sugar %
								1#-M	390.95	78.88	17	0.98	0.77	8.92	11.14
1#-S	379.55	66.08	16	1.00	0.74	9.65	11.90

No. 2 samples

The freezing fresh stalk of random 30 joint, thaws, peeling.Medullary substance portion (2#-M) and the skin zone (2#-S) of fresh stalk weigh respectively, measure respectively water content after pulverizing, and sugared content in water, the results are shown in Table 2.

Water content, glucose, fructose and sucrose content in table 22 sample

	Gross weight g	Water content %	Pol	Glu％	Fru％	Suc％	Total reducing sugar %
								2#-M	179.5	74.65	14.5	0.93	0.7	9.28	11.40
2#-S	227.4	65.47	15	1.12	0.81	10.27	12.74

Embodiment 2 fresh corn straw juice alcohol prepared by fermenting

Have the following steps by the method for fresh corn straw juice ethanol production:

1. harvesting corn stalk in 5 days after harvest corn, removes fringe, root and the leaf of fresh straw immediately, obtains clean fresh corn stalk.

2. get 20 tons of the clean fresh corn stalks that step 1 obtains, squeeze the juice with juice extractor, obtain 8 tons of 12 tons of fresh corn straw juices and fresh corn stalk slags.

3. in the fresh corn straw juice obtaining in step 2, contain sucrose 12%, glucose 0.8%, fructose 10%, being converted to the monosaccharide concentration of always can fermenting is 15%.Utilize multiple-effect vacuum method of evaporation concentrated, make the fermented monose total amount in juice be concentrated to 24%, obtain the concentrated sugary juice of 7.5 tons of processes.

4. 7.5 tons of the concentrated sugary juice that obtain in step 3 are driven into a 10m ³in fermentor tank, add 3.75kg urea as the required nitrogenous source of yeast growth, the sulphur acid for adjusting pH of recycling 10% is 4.8, then the material in fermentor tank is carried out to high-temperature sterilization at 115 ℃.

5. utilize the seed tank culture yeast saccharomyces cerevisiae seed of 500L, the yeast starter of cultivating 16-24h is driven into the 10m of sterilizing in step 4 ³in fermentor tank, inoculum size is 0.1%.

6. the temperature of controlling in the postvaccinal fermentor tank of step 5 is 32 ℃, intermittent stirring, and fermentation 24-48h, obtains karusen.

7. karusen is distilled in rectifying tower, obtain ethanol.

8. 8 tons of maize straw slags that step 2 obtained add 2kg urea, mixed spoon, sterilizing, then add cultured yeast starter in seeding tank, making inoculum size is 0.1%, mixes, be deposited into can the aseptic room of heat and moisture preserving in, carry out solid state fermentation, fermentation time is 24-72h, after fermentation ends, solid fermented material is carried out to vacuum-drying, the steam producing in drying process is incorporated into step 7 rectifying workshop section, and rectifying obtains ethanol.

9. liquid state fermentation and solid state fermentation obtain the ethanol that 1 ton of volumetric concentration is 99.8% altogether.

Claims

1. utilize fermentable sugars in fresh straw juice to prepare a method for alcohol fuel, it is characterized in that comprising the steps, percentage composition wherein by weight:

(1) collect fresh corn stalk, squeeze the juice and carry out solid-liquid separation, obtain straw juice and stalk slag;

(2) above-mentioned straw juice is concentrated, the monose total content that makes to ferment is 20%-30%;

(3) concentrated straw juice is adjusted to the state of suitable fermentation;

(4) add ethanol fermentation bacterial strain, fermentation obtains karusen, and further Separation and Recovery ethanol;

Wherein: the fresh corn stalk of step (1) is the stalk of collecting in 10 days after harvest corn; Straw juice accounts for the 30%-90% of total fresh corn stalk weight, contains sucrose 0-12% in straw juice, glucose 0-8%, and fructose 0-8%, being converted to the monosaccharide concentration of always can fermenting is 2%-18%.

2. it is characterized in that in accordance with the method for claim 1: the stalk slag that obtains adopts solid fermentation method by the residual fermentable sugars acquisition ethanol that further ferments.

3. it is characterized in that in accordance with the method for claim 1: the straw juice concentration method of step (2) adopts multiple-effect vacuum evaporation, thin film evaporation or nanofiltration membrane separation.

4. in accordance with the method for claim 1, it is characterized in that: the state that the concentrated straw juice of step (3) is adjusted to suitable fermentation comprises and adds bacterial strain to produce required nitrogenous source, then regulates pH value.

5. in accordance with the method for claim 4, it is characterized in that: nitrogenous source is yeast extract paste, urea or ammonium sulfate, nitrogenous source add-on is 0.01%-0.1% by weight; PH regulator is to 4.5-4.8.

6. in accordance with the method for claim 1, it is characterized in that: leavening temperature is 28-36 ℃, fermentation time is 24-48h.

7. it is characterized in that in accordance with the method for claim 1: the separation of ethanol that fermentation obtains karusen reclaims employing distillation concentrate or ultrasonic wave concentrate.