DESC:TECHNICAL FIELD
The present disclosure relates to the field of organic chemistry in general. Specifically, the present disclosure relates to a process for conversion of organic matter in biomaterial to organic compounds such as carbohydrates, including sugars. It relates to a process for conversion of biomass using an organic acid catalyst, preferably, sulfonic acid, to yield sugars. Particularly, the hemicellulose in the biomass is selectively converted to xylose.

BACKGROUND AND PRIOR ART OF THE DISCLOSURE
Sugar is one of the most popular forms of carbohydrates and is broadly composed of carbon, hydrogen, and oxygen. Obtaining sugar from various sources has been one of the most widely researched areas. It broadly involves break down of various organic sources to obtain sugars. These sources include biomaterial such as biomass, residues and waste products of various natural and man-made activities such as industrial wastes and effluents etc.

Biomaterials for example, biomass is abundantly available. Biomass is a renewable energy resource derived from the waste obtained after performing various activities and from numerous sources, including agricultural residues or agricultural wastes, by-products from industries such as timber industry, agricultural crops, raw material from the forests/woods, household wastes and wood etc. The biomass, among various other components also includes various complex carbohydrates such as hemicellulose, cellulose (both being carbohydrate polymers) and lignin etc. Sugars obtained from hemicellulose and cellulose, which are part of the biomass, are useful for production of variety of industrial chemicals via biological or chemical route.

Carbohydrates, such as sugars typically are produced from biomass deconstructed using one of the various pre-treatment processes followed by hydrolysis with enzymes broadly grouped as cellulases. Hydrolysis process requires the preparation of suspension of deconstructed biomass in a buffer solution to which enzymes are added and the process continues for more than 24 hours at a certain temperature depending on enzyme loading to get desired hydrolysis level. Major drawbacks of the enzyme catalysed process are enzyme cost, time involved and difficulty in enzyme re-usability. Pre-treatment process such as deconstruction of the biomass is a prerequisite for the enzymes to act and catalyse the hydrolysis of carbohydrate polymers in the biomass. In a typical deconstruction process, most of the hemicellulose is either lost or degraded to undesirable products such as Furfural, Hydroxymethyl furfural, and in certain instances , Humic substances and Humic acid.

In a typical biomass deconstruction and enzyme hydrolysis process, biomass is first size reduced, cooked in a reactor under high temperature and pressure in the presence of a solvent (such as ethanol or acetone) at 5-10 % (w/v) loading (depending on the process type), filtered to recover the liquor, subjected to water washing, dried and then hydrolysed using enzyme. Temperature and pressure of the hydrolysis process varies based on the principle of the pre-treatment agent.

In case of acid or base catalysed process, the temperature is in the range of about130 to 1800C and pressure from about 1 to 5 bar. Apart from this, in case of ammonia catalyzed process, the temperature is about 110-1300C with pressure from about 20 to 50 bar. Acetic acid or formic acid based process works in the range of about 120 to 1400C under pressure.

Known methods of hydrolysis of biomass require pre-treatment of biomass using various agents such as liquid or aqueous ammonia, sulfur dioxide, bases like sodium hydroxide, potassium hydroxide, and acids like sulphuric acid, hydrochloric acid, acetic acid and formic acid, for biomass deconstruction.

For the economics to improve, a process that can accommodate high biomass loading, perform simultaneous deconstruction and saccharification without the requirement of pre-treatment agents, operates at low temperature, without pressure and uses recyclable catalyst is desirable. There are a number of processes available for deconstruction and hydrolysis as separate operations but there is no process available that meets all the above criteria. The present disclosure overcomes the drawbacks observed in the prior art.

For example, prior art discloses a process for biomass hydrolysis to Furfural, wherein the process continues to the formation of Furfural from Xylose stage and is incapable of leading to formation of pure simple sugars of interest, i.e., the process leads to further degradation of Xylose to Furfural due to process conditions. Therefore, there is a need for processes that can produce sugars, with negligible or low amounts of Furfural.

Typically, dilute acid hydrolysis of biomass material is reported in literature using acids (typically sulphuric, hydrochloric or phosphoric acid) at concentrations of 1-10% using a moderate temperature (in the range of 100-2200C). The hydrolysis yields many other side products along with sugars. These compounds include Furfural, a product of dehydration of pentoses and Hydroxymethyl furfural (HMF), a product of the dehydration of hexoses. These compounds, along with acetic acid which is formed during initial decomposition of the hemicelluloses, as a result of hydrolysis of acetyl groups linked to the sugar, inhibit the later fermentation.

Sulphuric acid and Hydrochloric acid are the most commonly used catalysts for hydrolysis of lignocellulosic residues. In contrast to these acids, Phosphoric acid is less aggressive than other acids, which give solutions with higher concentrations of growth inhibitors of microorganisms, such as Furfural or Acetic acid. Dilute Phosphoric acid, on hydrolysates from sugar cane bagasse, has been shown to produce fermentable sugars with good yield. But it has limitation of recovery of the acid compound once used and hence has environmental concerns.

Therefore, there is a need to develop better and more economically viable processes for deconstruction of biomass to yield carbohydrates with minimum by-product formation.

SUMMARY OF THE DISCLOSURE
Accordingly, the present disclosure relates to a process of converting hemicellulose in biomass to sugar, said process comprising step of reacting the biomass with solvent and catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof.

DETAILED DESCRIPTION OF THE DISCLOSURE
The present disclosure relates to a process of converting hemicellulose in biomass to sugar, said process comprising step of reacting the biomass with solvent and catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof.

In an embodiment of the present disclosure, the biomass is selected from group comprising castor stalk, cotton stalk, red gram stalk, wood, groundnut shell and combinations thereof; the solvent is selected from group comprising water, alcohol and combinations thereof; and the sugar is selected from group comprising Xylose, Glucose, Arabinose and combinations thereof.

In another embodiment of the present disclosure, biomass: catalyst: solvent is used at a ratio ranging from to 1:1:5 to 5:1:20.

In yet another embodiment of the present disclosure, biomass: catalyst: solvent is used at a ratio of 2:1:9.

In still another embodiment of the present disclosure, the process is carried out at temperature ranging from 50°C to 120°C.

In still another embodiment of the present disclosure, the process is carried out for a time period ranging from 5 minutes to 60 minutes.

In still another embodiment of the present disclosure, the process is carried out at a temperature of 100°C for a time period of 20 minutes.

In still another embodiment of the present disclosure, the catalyst is taken at a concentration ranging from 2% w/w to 20% w/w.

In still another embodiment of the present disclosure, the catalyst is taken at a concentration of 10% w/w.

In still another embodiment of the present disclosure, the biomass is loaded into reactor at concentration ranging from 5% w/w to 25% w/w.

In still another embodiment of the present disclosure, the biomass is loaded into reactor at concentration of 20% w/w.

In still another embodiment of the present disclosure, said process is carried out in the reactor in continuous mode.

In still another embodiment of the present disclosure, said process results in hydrolysate comprising sugar selected from group comprising Xylose, Arabinose, Glucose and combinations thereof; by-product selected from group comprising Furfural and Hydroxymethylfurfural; catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof; and residual biomass comprising cellulose and lignin.

In still another embodiment of the present disclosure, the catalyst in the hydrolysate is recovered at a percentage ranging from 80 % w/w to 95 % w/w using ion exchange resin.

In still another embodiment of the present disclosure, 70% to 90% of the hemicellulose in the biomass is converted to the sugar, and 0.1% to 5% of the hemicellulose is converted into by-product.

In still another embodiment of the present disclosure, 70% to 90% of the hemicellulose in the biomass is converted to Xylose, and 0.1% to 5% of the hemicellulose is converted into Furfural.

In still another embodiment of the present disclosure, the cellulose and the lignin in the residual biomass is recovered at a percentage ranging from 70% w/w to 95% w/w.

In still another embodiment of the present disclosure, the cellulose content of the residue is hydrolysed with catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof, at an amount ranging from 20% w/w to 40% w/w to yield monomeric sugar selected from group comprising glucose, fructose and combinations thereof.

To overcome the non-limited drawbacks as stated in the background and to provide for simple, cost-effective and efficient method for yielding desirable carbohydrates, the present disclosure provides for a process which facilitates conversion of biomaterial to yield carbohydrates, such as but not limited to simpler carbohydrates, with minimum by-product formation.

The present disclosure relates to conversion of organic matter, from various sources such as but not limited to biomaterial, residues/waste from various natural as well as man-made activities, industrial wastes and effluents etc. to simpler organic compounds such as carbohydrates.

In an embodiment, the present disclosure relates to conversion of biomaterial such as biomass which includes wastes from living matter or just living matter, wastes derived from various activities including agriculture, agricultural residues, by-products from various industries such as timber industry, agricultural crops such as castor stalk, cotton stalk, red gram stalk etc., raw material from the forests/woods, household waste and wood etc.

In a non-limiting embodiment, the biomass includes but is not restricted to the organic matter present within the biomass.

The present disclosure also relates to a process for conversion of organic matter present in the biomass for the production of carbohydrates such as but not limited to sugars.

In an embodiment, the process of conversion of biomass involves minimum by-product formation.

In an embodiment of the present disclosure, the process of conversion of biomass to carbohydrates is by breakdown, deconstruction and hydrolysis or any combinations thereof.

In embodiments of the present disclosure, the steps of breakdown, deconstruction and hydrolysis occur simultaneously.

In embodiments of the present disclosure, the steps of breakdown, deconstruction and hydrolysis occur as a single step.

In a non-limiting embodiment, the hydrolysis is by selective hydrolysis.

Selective Hydrolysis is meant to be construed as specific hydrolysis of a particular component of a biomaterial, from various components present in the biomaterial.

In the method of the present disclosure, Hemicellulose component of the biomaterial is selectively hydrolysed by the catalyst.

In an exemplary embodiment of the present disclosure, the process employs catalyst for performing single step conversion of biomass to yield carbohydrates, such as but not limited to sugars.

In embodiments of the present disclosure, conversion of Hemicellulose yields Xylose, Arabinose and Glucose. The maximum yield obtained is for Xylose and least yield obtained is for Arabinose.

The biomass used in the present disclosure is obtained from Maharashtra and Gujarat, India.

In an embodiment of the present disclosure, the biomass does not need to be pre-treated before conversion into simpler compounds by employing the catalyst.

In an embodiment, the process of the present disclosure does not employ enzymes.

In an embodiment, the process of the present disclosure does not employ Cellulases.

In another embodiment of the present disclosure, the catalyst is a homogeneous or heterogeneous catalyst.

In embodiments of the present disclosure, the catalyst is used in the process of conversion of biomass at concentration ranging from 2 % w/w to 20 % w/w.

In an embodiment of the present disclosure, the catalyst is organic acid or its salt.

In an exemplary embodiment of the present disclosure, the organic acid is sulphonic acid.

In another exemplary embodiment of the present disclosure, the catalyst includes, but is not limited to Methane Sulfonic Acid or its salt. In a more preferred embodiment, the organic acid catalyst is Methane Sulphonic Acid.

In the present disclosure, the terms “Methane Sulphonic Acid” and “Methane Sulfonic Acid” and “Methanesulfonic acid” and “Methanesulphonic acid” and “Methylsulfonic acid” and “Methylsulphonic acid” and “MSA” are used interchangeably and have the same meaning and scope. It is a colorless liquid, represented by the chemical formula CH3SO3H or CH4O3S.

In an embodiment, solvent is used in the process of the present disclosure and the solvent is selected from group comprising ethanol, methanol, propanol and combinations thereof.

In an embodiment of the present disclosure, the organic acid or its salt catalyzes the hydrolysis of organic matter such as carbohydrate polymers present in biomass to yield monomeric carbohydrates such as sugars. The carbohydrate is, in an embodiment, selected from group comprising disaccharide, oligosaccharide and polysaccharide. In an exemplary embodiment, carbohydrate includes, but is not restricted to cellulose and hemicellulose.

In a preferred embodiment of the present disclosure, the organic acid catalyzes selective hydrolysis of organic matter such as but not limiting to hemicellulose present in the biomass to yield simpler carbohydrates such as sugars including, but not limited to xylose, arabinose and glucose; along with recovery of biomass rich in cellulose and lignin content. In a most preferred embodiment, Methane Sulphonic Acid is used for hydrolysis of biomass due to its capacity for single step conversion of biomass to sugar, low cost and recyclability.

In an embodiment of the present disclosure, the yield of Xylose from the hydrolysis of Hemicellulose in the biomass ranges from 70% to 90%.

In an embodiment of the present disclosure, there is very little hydrolysis of Cellulose from which Glucose is obtained. In an embodiment, the highest quantity of sugar obtained from the conversion process is of Xylose. This establishes the selective hydrolysis of Hemicellulose in the biomass by the process of the present disclosure.

The process of the present disclosure operates, in an embodiment, at low temperature and without pressure or autogeneous (self-generating) pressure to catalyse the selective hydrolysis and thus minimizes the energy required.

The present disclosure also minimizes the time and cost required for the hydrolysis process.
In an embodiment of the present disclosure, the process of conversion of biomass to sugars is completed in time period ranging from about 5 minutes to about 60 minutes.

In an embodiment of the present disclosure, the ratio of biomass: methanesulfonic acid: water, used in the conversion process rages from 1:1: 5 to 5:1:20.

In an embodiment of the present disclosure, the ratio of biomass: methanesulfonic acid: water, used in the conversion process is 2:1:9.

If the amount of acid used is increased, the rate of hemicellulose conversion remains the same at about 90-95%, but the sugars formed i.e. Xylose etc. start converting into undesired by-product Furfural, lowering down the yields of sugars. Thus, it is desired to use acid catalyst in the range mentioned above.

In embodiments of the present disclosure, the biomass loading in the process of conversion of biomass is at concentration ranging from 5% w/w to 25% w/w.

In embodiments of the present disclosure, the biomass loading in the process of conversion of biomass is at concentration of 20% w/w.

Biomass loading as used in the present disclosure is described as the amount of dry material that enters the process divided by the total mass of material and water added to the material.

In an embodiment, the process of the present disclosure enables recovery of the catalyst and its re-use.

In an embodiment of the present disclosure, the catalyst is recovered with the help of ion exchange resins.

In an embodiment of the present disclosure, the catalyst is Methanesulfonic acid. Since Methanesulfonic acid is fully soluble in water, no solvents are needed and the catalyst is recovered by employing Ion exchange resin. This is an energy efficient and environment friendly process of recovery of the catalyst.
As methane sulfonic acid is highly water soluble, it is difficult to separate it by extraction from water solution. Thus, ion exchange resin is used for separation of methane sulfonic acid from water.

In an embodiment, the recovery of methane sulfonic acid is about 95% and the process does not require any solvent, so it is environment friendly. The ion exchange resins are also reusable.

The process of the present disclosure comprises the following acts:
i. Biomaterial such as Biomass is fed into a reactor with catalyst such as but not limited to organic acid or its salt to obtain a mixture.
ii. The mixture is heated for a short time period without pressure and kept under stirring;
iii. Hydrolysate containing carbohydrates including sugars and catalyst, along with residual biomass enriched in Cellulose and lignin is collected.
iv. The hydrolysate is passed over ion exchange resin to entrap the catalyst on resin and the aqueous sugar solution is directly used for fermentation or other applications.
v. The resin is washed with ammonium hydroxide to get salt form of catalyst in aqueous layer which is passed over acidic resin to recover pure acid catalyst.

In embodiments of the present disclosure, the Reactor is selected from group comprising Batch Reactor (autoclave) and Continuous Reactor.

In an embodiment, the process of the present disclosure is carried out in continuous mode.
The continuous mode of conversion of biomass to simpler compounds is carried out in a Screw Extruder type Reactor.

In embodiments of the present disclosure, experimental conditions for continuous and non- continuous process of the present disclosure are the same.

In an embodiment, the process comprises steps of injecting biomass and catalyst at one end of a reactor using a screw extruder, at a specific flow rate of 10-100g/min depending on the reactor dimensions and for a particular period of time (20 min of residence time) at specific temperature (90-110 0C) and collecting hydrolysate containing carbohydrates including sugars, along with solid residual biomass from the other end of the reactor.
In an exemplary embodiment, the catalyst is an aqueous solution of sulphonic acid, wherein the sulphonic acid is methanesulfonic acid.

In a preferred embodiment, methane sulphonic acid is used as catalyst which due to its acidic nature in presence of water performs selective and controlled hydrolysis of organic matter including but not limited to hemicellulose, leaving behind solid residue containing cellulose and lignin. A representation of the reaction that occurs during the selective and controlled hydrolysis of organic matter using methane sulphonic acid is as follows:

Biomass (Hemicellulose, cellulose, lignin) + water + methane sulphonic acid ? Xylose + Arabinose + Glucose + solid biomass enriched in lignin and cellulose + recovered methane sulphonic acid.

In a preferred embodiment of the present disclosure, the mixture is heated for time duration ranging from about 5 minutes to about 60 minutes, preferably about 20 minutes, at temperature ranging from about 50°C to about 120°C, preferably about 100°C.

In a preferred embodiment of the present disclosure, methanesulfonic acid is used as a catalyst at a concentration of 10% w/w. The process of conversion of biomass is carried out for 20 minutes at a temperature at 110°C and gives more than 90 % hydrolysis of hemicellulose, restricting the products to sugars, specifically Xylose, with a very small amount of Furfural being formed.

In a preferred embodiment of the present disclosure, about 70 to 90% Hemicellulose in the biomass hydrolyses to its monomeric sugars with less than about 5% converted to by-product Furfural under mild conditions. Determination of the Hemicellulose, Cellulose and Lignin content in the biomass is done using HPLC with Refractive Index (RID) detector as well as a standard NREL (National Renewable Energy Laboratory) protocol. A person skilled in the art will know the essential features of the standard protocols for determination of components of the biomass.

In another embodiment of the present disclosure, Cellulose present in the residual biomass is further subjected to hydrolysis with catalyst under particular experimental conditions to yield sugars, specifically Glucose.
In an embodiment of the present disclosure, the catalyst includes but is not limited to organic acids or its salt, preferably sulphonic acid or its salt.

In a preferred embodiment, the catalyst is Methane sulphonic acid or its salt.

In a further embodiment of the present disclosure, cellulose remaining in the residual biomass is hydrolysed to yield sugars including, but not limited to glucose and fructose. At the end of this hydrolysis, Lignin is separated as solid unhydrolysed material by filtration to be used as fuel or other applications.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for examples illustrating the above described embodiments, and in order to illustrate the embodiments of the present disclosure certain aspects have been employed. The examples used herein for such illustration are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES

EXAMPLE 1: CATALYSIS OF BIOMASS
The biomass used in the present disclosure is obtained from Maharashtra and Gujarat, India. The biomass obtained from the fields in dry form (containing 7 to 12% moisture) is first subjected to size reduction using cutter grinder (having mesh of size- 2 mm). Thus, biomass of size less than or equal to 2mm is used for the present process. The ratio of biomass: methane sulphonic acid: water is about 2:1:9.

The reactor autoclave with 1 litre capacity having stirring, cooling, temperature and pressure sensing arrangement is fed with about 40g biomass (e.g. castor stalk, cotton stalk, red gram and sugarcane trash) and aqueous solution of about 10% w/w Methane Sulfonic acid at amount of about 200 g (20 g methane sulfonic acid in 180 g of water). The Reactor is maintained at 100 0C for 20 min under stirring at 200 rpm to perform the hydrolysis.

The reaction mixture comprising biomass, methane sulphonic acid and water is stirred using stirrer connected to motor under closed condition. Water is added after the reaction followed by filtration to obtain hydrolysate containing monomeric sugars, minimal by-product- furfural, methane sulphonic acid and solid residue containing cellulose and lignin, which are collected from the outlet pipe and analyzed through HPLC.

The hydrolysate is passed over ion exchange resin to entrap the catalyst on resin and the aqueous sugar solution is directly used for fermentation or other applications.

The resin is washed with ammonium hydroxide to get salt form of catalyst in aqueous layer which is passed over acidic resin to recover pure acid catalyst,

The determination of sugars in the hydrolysate is done using HPLC with Refractive Index detector (RID) as well as NREL (National Renewable Energy Laboratory) protocol. The by-product Furfural is measured using UV detector set at 282 nm using 90:10 Water: Acetonitrile mobile phase (with 1 ml 60% Perchloric acid) at 1 ml flow per minute using C18 HPLC column.

The hydrolysate is found to contain Xylose as the major component along with Arabinose and Glucose; and the residual biomass is enriched in Cellulose and Lignin content. About 70 to 90% Hemicellulose in the biomass is hydrolysed to its monomeric sugars with less than about 5% converted to by-product Furfural under the above mentioned mild conditions. The cellulose in the residual biomass is further hydrolysed with Methane Sulfonic acid at an amount of about 20 to 40% w/w to yield hydrolysate containing Glucose and fructose.

EXAMPLE 2: RECOVERY OF CATALYST
The objective of this example is to recover Methanesulfonic Acid for re-use after the process of conversion of biomass to sugar is carried out with the Methanesulfonic acid. This is one of the most advantageous, inventive and economic features of the process of the present disclosure that the Methanesulfonic acid is re-usable after acting as a catalyst.
After the process of conversion of biomass is completed, the hydrolysate containing sugars and Methane Sulfonic Acid is subjected to resin treatment. In the first step, hydrolysate is passed through Indion 890 resin bed or similar free base form resins. The acidity of hydrolysate is adsorbed in the form of methane sulfonic acid on the resin. The aqueous solution containing sugars, is used for fermentation or other desired application.

Thereafter, the resin is eluted using ammonium hydroxide solution, resulting in ammonium methane sulfonate salt in the eluent. The eluent is then passed through Amberlyte IR 120 resin or similar acidic resin giving aqueous solution of methane sulfonic acid which is recycled for pre-treatment. The ion exchange resin is regenerated by giving a wash with mineral acid.

EXAMPLE 3: EFFECT OF CONCENTRATION OF METHANE SULPHONIC ACID ON YIELD OF MONOMERIC SUGARS
In this example, the effect of varying amounts of the catalyst (i.e. from 0.25 grams to 2.5 grams) - Methane sulphonic acid, at varying percentages (i.e. from 5% w/w to 50% w/w), upon the yield of the monomeric sugars- Xylose, Arabinose and Glucose from conversion of biomass and the production of the by-product- Furfural is assessed, using 1000 mg of biomass (i.e. red gram stalk).

TABLE 1: EFFECT OF DIFFERENT CONCENTRATIONS OF METHANE SULFONIC ACID (RED GRAM STALK)
Exp No Reaction conditions Catalyst % w/w Total xylose + arabinose (mg) Glucose (mg) Furfural (mg) % hydrolysis (to xylose) % hydrolysis (to glucose) % hydrolysis (to furfural) % Total hemicellulose hydrolysis % Total cellulose hydrolysis
1 Catalyst – Methane sulphonic acid (MSA)- 0.25g, H2O- 4.75g,
100°C,
20 min 5 98.82 16.17 1.3 50.99 3.8 0.9 51.98 3.55
2 MSA - 0.5g, H2O - 4.5g, 100°C,
20 min 10 132.13 37.49 4.1 69 8.8 3.1 72.14 8.23
3 MSA -1g, H2O -4g, 100°C,
20 min 20 116 45.59 11.1 60 10.8 8.4 68.48 10.01
4 MSA -1.5g, H2O -3.5g, 100°C,
20 min 30 88.59 47 15.1 46 11.1 11.5 57.50 10.42
5 MSA -2g, H2O -3g, 100°C,
20 min 40 45.45 53.32 7.1 23.5 12.6 5.4 28.94 14.29
6 MSA -2.5g, H2O -2.5g, 121°C,
20 min 50 15.3 56.40 16.7 8 13.3 12.7 20.75 17.38

INFERENCE: From the above table, it is evident that Methane sulphonic acid at a concentration of 2% w/w to 20 % w/w when used for hydrolysis of biomass, brings about the maximum selective hydrolysis of hemicellulose, resulting in the maximum yield of the monomeric sugars with reduced production of by-product Furfural.

Thus, Methane Sulfonic Acid provides efficient conversion of biomass to sugar with reduced by-product formation at different concentration values, ranging from 2 % w/w to 20% w/w.

EXAMPLE 4: EFFECT OF BIOMASS LOADING ON YIELD OF MONOMERIC SUGARS:
In this example, the effect of biomass loading at various percentages (i.e. ranging from 5 % w/w to 50% w/w) upon the yield of monomeric sugars from biomass is assessed.

TABLE 2: EFFECT OF BIOMASS LOADING (RED GRAM STALK)
Exp No Reaction condition Biomass loading % (w/w) Biomass wt, (mg) Total xylose + arabinose (mg) Glucose (mg) Furfural (mg) % hydrolysis (xylose) % hydrolysis (glucose) % hydrolysis (furfural) % Total hemicellulose hydrolysis % Total cellulose hydrolysis
1 Catalyst-MSA 0.5g, H2O 4.5g, 100°C, 20 min 5 250 34.19 10.46 1.01 70.37 9.9 3.0 73.4 9.9
2 10 500 80.25 24.20 2.86 82.44 11.4 4.3 86.8 11.5
3 20 1000 120.22 35.73 4.01 61.76 8.4 3.0 64.8 8.9
4 30 1500 149.16 41.75 4.46 51.08 6.5 2.2 53.3 6.6
5 40 2000 162.81 46.63 4.55 41.84 5.5 1.7 43.5 5.8
6 50 2500 218.58 58.22 5.44 44.91 5.5 1.6 46.5 5.7
INFERENCE: From the above table, it is evident that biomass loading at a concentration range of 5% w/w to 20 % w/w, when used for hydrolysis of biomass, brings about the maximum hydrolysis of hemicellulose, resulting in the maximum yield of the monomeric sugars with reduced production of by-product Furfural.

EXAMPLE 5: EFFECT OF TEMPERATURE ON YIELD OF MONOMERIC SUGARS
In this example, the effect of temperature on the yield of monomeric sugars from biomass is assessed using 10% methane sulphonic acid. 200g of 10% methane sulphonic acid aqueous solution and 40g of biomass is used in this example. Stirring speed of the agitator in the reactor is 200 rpm.

TABLE 3: EFFECT OF TEMPERATURE ON HYDROLYSIS OF BIOMASS (RED GRAM STALK)

Reaction condition Xylose + Arabinose (mg) Glucose
(mg) Furfural
(mg) % hemicellulose hydrolysis to xylose % Total hemicellulose hydrolysis % Total cellulose hydrolysis
110°C, 20min, 200rpm 6704 3150 271 81 86.04 18.3
100°C, 20min, 200rpm 5708 1499 113 68.19 70.31 8.7

INFERENCE: From the results indicated in table 3, it is observed that the hydrolysis of biomass using methane sulphonic acid, carried out at a temperature ranging from 50 °C to 120°C yields the maximum amount of the monomeric sugars- Xylose, Arabinose and glucose from biomass with reduced by-product formation.

EXAMPLE 6: HYDROLYSIS OF BIOMASS FROM VARIOUS SOURCES
In this example, different sources of biomass are evaluated for the yield of monomeric sugars upon hydrolysis of each type of biomass. 40 g of biomass which contains 15-18 % of hemicellulose is used in this example. Stirring speed of the agitator in the reactor is 200 rpm.

Tables 4 and 5 depict the yields of monomeric sugars from various sources of biomass.

TABLE 4: HYDROLYSIS OF COTTON STALK
Reaction condition Xylose + Arabinose (mg) Glucose
(mg) Furfural
(mg) % hemicellulose hydrolysis to xylose % Total hemicellulose hydrolysis % Total cellulose hydrolysis
110°C, 20min, 200rpm 5639 1533.5 330.69 83 90.6 9.72
100°C, 20min, 200rpm 4933 822.5 82 64.5 66.2 4.6
100°C, 60min, 200rpm 4995 1160 172.3 73.52 77.52 7.36

TABLE 5: HYDROLYSIS OF CASTOR STALK
Reaction condition Xylose + Arabinose (mg) Glucose
(mg) Furfural
(mg) % hemicellulose hydrolysis to xylose % Total hemicellulose hydrolysis % Total cellulose hydrolysis
110°C, 20min, 200rpm 4988 2443 319.3 79.88 87.98 15.72
100°C, 20min, 200rpm 4575 1771 107.6 72.98 75.7 11.39
100°C, 60min, 200rpm 4960.4 2274.3 239.7 79 85 14.63

INFERENCE: From the tables above, it is concluded that the process of the present disclosure provides efficient conversion of different kinds of biomass to sugars, with minimal by-product formation.

ADVANTAGES:
1. The present disclosure enables the use of biomass at higher solid loading of about 20% in a less energy intensive process to selectively hydrolyse hemicellulose in the biomass to sugars.

2. The process of the present disclosure enables selective hydrolysis of hemicellulose portion of complex biomass to component sugars without significant furfural formation.

3. Known methods of hydrolysis of biomass require pre-treatment of biomass using various agents such as liquid or aqueous ammonia, sulfur dioxide, bases like sodium hydroxide, potassium hydroxide, acids like sulphuric acid, hydrochloric acid, acetic acid and formic acid, for biomass deconstruction. However, the present process does not require the step of pre-treatment of biomass and hence is more economical, less energy intensive, a simpler process and saves time.

4. The process of the present disclosure eliminates use of expensive enzymes by combining hydrolysis and deconstruction of the biomass in a single step and uses economical catalyst such as methane sulfonic acid. Enzyme based processes of hydrolyzing biomass require long durations of about 24-48 hours whereas the present process of hydrolysis using methane sulphonic acid requires short duration of about 5 minutes to 60 minutes. This is one of the advantageous features of the process of the present disclosure over the methods of the prior art.

5. Further, pre-treatment processes such as deconstruction of the biomass are a pre-requisite for the enzymes to act and catalyse the hydrolysis of carbohydrate polymers in the biomass. Majority of the processes for biomass pre-treatment first involve the step of delignification of biomass to obtain a residue containing cellulose and hemicellulose. In the second step, hydrolysis of the cellulose and hemicellulose is performed using enzymes or acids. On the other hand, the method of the present disclosure does not require the steps of ‘pre-treatment followed by hydrolysis’ as in case of the prior art methods, but makes use of the methane sulphonic acid in such a way that it selectively hydrolyses the hemicellulose content of the biomass to monomeric sugars- xylose, glucose and arabinose, with minimum by-product formation. The residue obtained from this step is enriched in cellulose and lignin. The residual biomass enriched in cellulose obtained by the process of the present disclosure may be further hydrolysed to obtain component sugars.

6. The process of the present disclosure is performed under mild reaction conditions and utilizes less time.

Thus, the present disclosure is able to successfully overcome the various deficiencies of methods of the prior art and provide for an improved process for conversion of biomass to yield sugars with minimal by-product formation in an energy efficient manner.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

The foregoing description of the specific embodiments fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising” wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:1. A process of converting hemicellulose in biomass to sugar, said process comprising step of reacting the biomass with solvent and catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof.

2. The process as claimed in claim 1, wherein the biomass is selected from group comprising castor stalk, cotton stalk, red gram stalk, wood, groundnut shell and combinations thereof; the solvent is selected from group comprising water, alcohol and combinations thereof; and the sugar is selected from group comprising Xylose, Glucose, Arabinose and combinations thereof.

3. The process as claimed in claim 1, wherein biomass: catalyst: solvent is used at a ratio ranging from to 1:1:5 to 5:1:20.

4. The process as claimed in claim 1, wherein biomass: catalyst: solvent is used at a ratio of 2:1:9.

5. The process as claimed in claim 1, wherein the process is carried out at temperature ranging from 50°C to 120°C.

6. The process as claimed in claim 1, wherein the process is carried out for a time period ranging from 5 minutes to 60 minutes.

7. The process as claimed in claim 1, wherein the process is carried out at a temperature of 100°C for a time period of 20 minutes.

8. The process as claimed in claim 1, wherein the catalyst is taken at a concentration ranging from 2% w/w to 20% w/w.

9. The process as claimed in claim 1, wherein the catalyst is taken at a concentration of 10% w/w.

10. The process as claimed in claim 1, wherein the biomass is loaded into reactor at concentration ranging from 5% w/w to 25% w/w.

11. The process as claimed in claim 1, wherein the biomass is loaded into reactor at concentration of 20% w/w.

12. The process as claimed in claim 1, wherein said process is carried out in the reactor in continuous mode.

13. The process as claimed in claim 1, wherein said process results in hydrolysate comprising sugar selected from group comprising Xylose, Arabinose, Glucose and combinations thereof; by-product selected from group comprising Furfural and Hydroxymethylfurfural; catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof; and residual biomass comprising cellulose and lignin.

14. The process as claimed in claim 13, wherein the catalyst in the hydrolysate is recovered at a percentage ranging from 80 % w/w to 95 % w/w using ion exchange resin.

15. The process as claimed in claim 1, wherein 70% to 90% of the hemicellulose in the biomass is converted to the sugar, and 0.1% to 5% of the hemicellulose is converted into by-product.

16. The process as claimed in claim 1, wherein 70% to 90% of the hemicellulose in the biomass is converted to Xylose, and 0.1% to 5% of the hemicellulose is converted into Furfural.

17. The process as claimed in claim 13, wherein the cellulose and the lignin in the residual biomass is recovered at a percentage ranging from 70% w/w to 95% w/w.

18. The process as claimed in claim 17, wherein the cellulose content of the residual biomass is hydrolysed with catalyst selected from group comprising methane sulphonic acid, methane sulphonic acid salt and combinations thereof, at an amount ranging from 20% w/w to 40% w/w to yield monomeric sugar selected from group comprising glucose, fructose and combinations thereof.