Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF ETHANOL"

Abstract

This invention relates to an improved process for the preparation of ethanol. The Process steps are: growing a pregrown yeast in the fermentation medium containing sucrose as carbon source and nitrogen source such as herein described in presence of a zeolite catalyst for a period ranging from 6 to 24 hrs. at a temperature ranging between 20 to 35°C; separating the ethanol produced by conventional distillation method.

Full Text

This invention relates to an improved process for the preparation of ethanol which comprises of carrying out fermentation of sucrose in the presence of a medium containing nitrogen, and in presence of synthetic zeolite catalyst and recovering the ethanol formed by conventional methods like distillation . General background of zeolites. Industrial grade ethanol. a key product in the conversion of sugars and starches to energy and chemical feedstocks, is producde in India exclusively through the fermentation of sugar cane molasses using yeast. Improvement in such a rout of molasses utilization is realized mainly through enhancement in volumetric productivity and conversion efficiency at adequately high product concentration. Conventional batch fermentation are carried out by pre grown yeast and pretreat-ed sugarcane molasses at a concentration of 150 g 1 in huge fermenters over a period of 24 - 48 hrs. Zeolites like Sili-calite would decrease in fermentation time as the fermentation rate is accelerated by 40 - 60%. Because of faster fermentation rate, contamination is kept to the minimum as inhibitory levels of alcohol is reached faster. Zeolites are crystalline, hydrated aluminosilicates of group I and group II elements, in particular sodium, potassium, magnesium, calcium,strontium, barium etc. These unique zeolite structures are composed of three dimensional network of SiC>4 and AlO^ tetrahydra in which a unit negative charge is associated with each AlO^ tetrahydron. This charge must be counter balanced by a positive inorganic or organic ion. Depending on the type of connection between tetrahedral building blocks, linear or pseudolinear channels may be formed with diameters ranging from 4.2 to 7.4 A. The character and composition of the zeolite prepared according to the process disclosed in our patent Nos. 155205, and Indian Patent nos. 182/Del/88. 367/Del/88, 905/Del/89, 900/Del/89 are given below: The structural formula of a zeolite is best expressed for the crystalline unit cell as:M x/n (AlC^x ( SiC^ ) v ) . WI^O • where M is the cation of valence n. W is the number of water molecules and the ratio Y/x usually has variable values depending upon the structure. The sum (x + y) is the total number of tetrahedra in the unit cell. The framework contains channels and interconnected voids which are occupied by the cation and water molecules. The cations are quite mobile and may usually be exchanged to varying degrees by other cations. Intracrystalline zeolite water in many zeolites is removed continuously or reversibly. The zeolite used in the fermentation process of the present invention can be any known synthetic zeolites. We have observed that the use of the zeolite described and claimed in our patent No. 155205 is the preferred one. Application in general: Since the first synthetic preparation of zeolites by Barrer in 1940's, these aluminosilicates have been used in large quantities for the hydrocarbon conversion, size/shape selective heterogenous catalysis, gas separation and purification as well as for ion exchange dessicate and sorbing processes. However, with the last few years, considerable effort has been directed at new uses of zeolites as advanced material for eg. in the field of solar energy, chemical sensors, zeolite lasers, displays, selective membrane and thin films for the gas seperation and recently in biotechnological applications. The prior art procedure for ethanol production which is a key product in the bioconversion of plant biomass constituents to liquid fuel and chemical feedstock. The major raw materials for fermentative ethanol production are saccharine products mainly of sugar stalk crops such as sugar cane or hybrid sorghum. Starchy materials derived either from cereal grains such as corn, wheat, rice, barley and grain sorghum or from tuber and root crops such as potato, beet, Jerusalem artichoke and tapioka. Also the monosaccharides present derived from cellulosic raw materials constitute the primary substrates in the fermentation pathways. Hexoses such as glucose and fructose derived from sugar stalkcrops, starches or cellulose are readily utilized by Sa.ccharomyc.es strains used in commercial scale ethanol production . Biostil Process : The main features of this continuous process with yeast recycle to that the fermentation and distillation are coupled, the beer being continually cycled after initial removal of yeast and subsequent stripping of ethanol in a vaporizer. The ethanol concentration in tha fermentor is maintained low at about 5% (w/v) to minimize product inhibi- tion effects. This can be minimized by use of thfe catalyst as described in this applications as it increases the initial specific ethanol productivity SivaRaman et al, 1994. The biostil process is limited by the buildup of inhibitory no fermentable byproducts and therefore an osmotolerant strain of Saccharomyces pombe is used. With the addition of zeolite strains with better fermentative capacity like Saccharomyces cerevisiae can be used (SivaRaman et al, 1994). Vogelbusch Cascade Process: This includes a combination of batch and continuous process. Between 5 and 7 production fermentors are operated in series, the first tank being aerated and the others having COi mixing devices. By the addition of zeolite the fermentation time can be reduced, which would subsequently reduce the cost of the process. Accordingly the present invention provides for an improved process for the preparation of ethanol which comprises; growing a pregrown yeast of the kind as herein described in the fermentation medium containing sucrose as carbon source and nitrogen source such as herein described characterized in that in presence of a zeolite catalyst in the range of 0.05 - 2 % w/v for a period ranging from 6 to 24 hrs. at a temperature ranging between 20 to 35°C; separating the ethanol produced by conventional distillation method. This process of the present invention is described herein with reference to following examples, which are illustrative only and should not be construed to limit the scope of the present invention in any manner. Example 1 This example illustrates the preparation of crystalline sodium aluminosilicate (ie. ZSM5. SiO2/AI2O3=86). A solution of 56 g. of sodium silicate ( 27.17% SiO2. 84% Na20,64.43% H20) in 70 ml of water was transferred to the stainless steel autoclave and 5.8 g. of tetrapropylammonium bromide (TPA.Br) dissolved in 35 ml of water was added to the above solution with stirring. To the resulting mixture, a solution of 0.7 g. sodium aluminosilicate (43.68% A12O3, 39% Na20 and 17.3% H2O) in 17.5 g of water was added and followed by a slow addition of 5.6 g, of sulfuric acid in 17.5 g. of water. The reaction vessel was tightly closed and maintained at 150°C for 136 h. The resulting crystalline product was washed free of bromide ions with distilled water, dried at 120°C. for 16 h. followed by an air calcination at 540°C for 2 hrs. as described in own patent No. 155205. The resultant crystalline product had the following composition: 0.97 Na2 O :A1203:85.6Si02. Example 2 This example illustrates the preparation of crystalline aluminosilicate (silicalite, SiO2 /AI2O3 = 300). catalyst designated as ZSM 5. 35.32 g. of sodium silicate (27.17 of Si02, 8.4% Na2O) was diluted with 200 g. of water, and to this a solution of 4 g. of triethyl - n - butyl ammonium bromide (TEBA Br) in 20 g. of water was added under continuous stirring. An acidic solution was made comprising 0.26 g. A12(S04)3. 16H2O and 3.54 g. H2S04 in 48 g. of water. This acidic solution was then added slowly to a previously mixed solution under vigorous stirring. The gel so formed was continuously stirred for half hour and the pH was observed to be 10.1. The resultant gel had the composition in terms of oxide mole ratios as follows(Indian patent 900 DEL89 /6.10.89) 24.0 Na2O :4.2 (TEBA)2O :0:400 SiO2 : 3285 H2O as described and claimed in our copending patent application no. 900/Del/89. The gel mixed was crystallised in a stainless steel autoclave under autogenous pressure at 180° C. for 36 h. After this, the subsequent liquid was separated by filtration. The pH of the supernatant was recorded to be 11.9. The solid product was washed with hot water till the washings were free from sulfate ions and organic matter. The solid product was dried in an air oven at 120° C. for 12 hours to yield material having final composition: 0.8 Na20 : A12O3 : 300 SiO2 Example 3 Yeast cells. Saccharomyces cerevisiae (flocculent) NCIM 3528 designated as Strain 17 and deposited at Natinal Collection of Industrial Microorganisms, grown in a medium of the fol- lowing composition : Sucrose 50 g.L . Peptone 5 g.L ; yeast extract. 3 g.L ; malt extract 3 g.L , pH 6.5 : temp. 30°C.Cells harvested and used without storage.Yeast cells (3 - 5 g.wet wt. ) were suspended in 100 ml of 15% Sucrose without zeolite as control and 0.1 % yeast extract and with Silicalite ( R = 300) ( particle size 1 u; pore size 5.1 -5.8 ) with 0.1% yeast extract and kept at 30°C; samples were removed at fixed time intervals and estimated for ethanol. ( Reid and Truelove, 1952). Ethanol production after ( in Percentage) w/v (Table Removed) Sucrose concentration used was 15 % ( reducing sugar ). It can be seen from the above table that in the initial stages of fermentation the fermentation rate is 20 - 30 % higher than that of the control ( without zeolite). i Example 4 •l Yeast cells, Saccharomyces cerevisiae Killer, (semi-floccu-lent) NCIM 3578. was grown in a medium of the following composition : Sucrose 50 g.L , Peptone 5 g . L ; yeast extract, 3 g.L~ , malt extract 3 g.L , pH 6.5 : temp. 30°C.Cells harvested and used without storage.Yeast cells (3 - 5 g, wet wt.) were suspended in 100 ml 15% Sucrose with 0.1 % yeast extract without zeolite as control and with zeolite, Silicalite ( R = 300) ( particle size 1 u; pore size 5.1 -5.8 ) and kept at 30°C; samples were removed at fixed time intervals and estimated for ethanol. Ethanol production after ( in Percentage ) w/v (Table Removed) Sucrose concentration used had 15 % reducing sugar. It can be seen from the above table that in the initial stages of fermentation rate is very high almost 40 - 60 higher than that of the control ( without zeolite). Example 5 "Yeast cells. Saccharomyces uvarum (non-flocculent) NC1M was grown in a medium of the following composition : Sucrose 50 g.L . Peptone 5 g.L ; yeast extract. 3 g . L~ : malt extract 3 g.L . pH 6.5 ; temp. 30°C.Cells harvested and used without storage. Yeast cells ( 5 g. wet wt) were suspended in 100 ml 15% Sucrose with 0.1 % yeast extract and with and without zeolite. Silicalite ( R = 300) ( particle size 1 ;Uj" pore size 5.1 - 5.8 ) and kept at 30°C: sample1" Ethanol production after ( in Percentage) w/v (Table Removed) Sucrose concentration used had 15 % reducing sugars Example 6 Yeast cells, Saccharomyces cerevisiae (flocculent) NCIM 3528 was grown in a medium of the following composition : glucose 50 g.L -1 , Peptone 5 g.L-1: yeast extract, 3 g.L"1; malt extract 3 g.L-1 , pH 6.5 ; temp. 30°C.Cells harvested and used without storage. Yeast cells (3 - 5 g. wet wt) were suspended in 100 ml Glucose with 0.1 % yeast extract and with and without zeolite, Silicalite ( R = 300) ( particle size 1 u: pore size 5.1 - 5.8 ) and kept at 30°C; samples were removed at fixed time intervals and estimated for ethanol. (Table Removed) Glucose concentration used had 15 % reducing sugars. Example - 7 Yeast cells, Saccharomyces cerevisiae,Killer, (semi- floccu-lent) NCIM 3578 was grown in a medium of the following composition : glucose 50 g.L , Peptone 5 g.L : yeast extract, 3 g.L : malt extract 3 g.L , pH 6.5 : temp. 30°C.Cells harvested and used without storage.Yeast cells (3 - 5 g. wet wt) were suspended in 100 ml Glucose with 0.1 % yeast extract and with and without zeolite. Silicalite ( R = 300) ( particle size 1 µ; pore size 5.1 - 5.8 ) and kept at 30°C; samples were removed at fixed time intervals and estimated for ethanol. (Table Removed) Glucose concentration used was 15 % ( reducing sugar ). Example 8 Yeast cells, Saccharomyces uvarum, (non- flocculent) NCIM was grown in a medium of the following composition : glucose 50 g.L -1 , Peptone 5 g.L-1; yeast extract. 3 g.L-1: malt extract 3 g.L , pH 6.5 : temp. 30°C.Cells harvested and used without storage.Yeast cells (3 - 5 g, wet wt) were suspended in 100 ml Glucose with 0.1 % veast extract and with and without zeolite. Silicalite { R = 300) ( particle size 1 p: pore size 5.1 - 5.8 ) and kept at 30°C: samples were removed at fixed time intervals and estimated for ethanol. .awoff (Table Removed) Glucose concentration used was 15 % ( reducing sugars equivalent ). We Claim: 1. An improved process for the preparation of ethanol which comprises; growing a pregrown yeast of the kind as herein described in the fermentation medium containing sucrose as carbon source and nitrogen source such as herein described characterized in that in presence of a zeolite catalyst in the range of 0.05 - 2 % w/v for a period ranging from 6 to 24 hrs. at a temperature ranging between 20 to 35°C; separating the ethanol produced by conventional distillation method. 2. An improved process as claimed in claim 1 wherein the nitrogen source is selected from urea, ammonium sulfate, peptone or mixture thereof, having concentration in the range of 0.05 to 2%. 3. An improved process as claimed in claims 1 to 2 wherein the zeolite catalyst used is Zeoloite or Silicalite. 4. An improved process as claimed in claims 1 - 3 wherein the concentration of solution of sucrose is in the range from 10-30 % total sugars. 5. An improved process for the preparation of ethanol as substantially described herein with reference to the examples.

Documents:

1024-del-1996-abstract.pdf

1024-del-1996-claims.pdf

1024-del-1996-complete specification (granted).pdf

1024-del-1996-correspondence-others.pdf

1024-del-1996-correspondence-po.pdf

1024-del-1996-description (complete).pdf

1024-del-1996-form-1.pdf

1024-del-1996-form-2.pdf

1024-del-1996-form-3.pdf

1024-del-1996-form-4.pdf