Potential of Biomass Sources for Fural-Based Fuel Production in the Consideration as a Green Fuel

In Vietnam, although quite modest, but since 1998, there have been investments in nanotechnology research. To date, many research results of nanotechnology application have been published in theory and experiment. Along with research units, the business sector also boldly applied nanotechnology in production. In this paper, the authors mention research, application, testing of fuel saving measures and emission reductions on diesel engines. It focuses on measures to improve fuel efficiency (including the use of emulsified fuels and the use of fuels containing nano-technology additives and especially the combination of the above two types) to test Control combustion in the direction of increasing capacity, saving fuel and reducing emissions. This measure has the same advantages as: it can be used on circulating engines without interfering with engine "hardware". The results contribute to the construction of technologies to produce renewable fuels from agricultural waste, to participate in solving national energy security and environmental pollution caused by agricultural wastes. The research results confirmed that rapid pyrolysis and hydrodeoxygenation are advanced and feasible technologies for converting agricultural waste biomass into liquid fuel.


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Abstract-In Vietnam, although quite modest, but since 1998, there have been investments in nanotechnology research.To date, many research results of nanotechnology application have been published in theory and experiment.Along with research units, the business sector also boldly applied nanotechnology in production.In this paper, the authors mention research, application, testing of fuel saving measures and emission reductions on diesel engines.It focuses on measures to improve fuel efficiency (including the use of emulsified fuels and the use of fuels containing nanotechnology additives and especially the combination of the above two types) to test Control combustion in the direction of increasing capacity, saving fuel and reducing emissions.This measure has the same advantages as: it can be used on circulating engines without interfering with engine "hardware".The results contribute to the construction of technologies to produce renewable fuels from agricultural waste, to participate in solving national energy security and environmental pollution caused by agricultural wastes.The research results confirmed that rapid pyrolysis and hydrodeoxygenation are advanced and feasible technologies for converting agricultural waste biomass into liquid fuel.Index Terms-2,5-Dimethylfuran; Potential; Alternative Fuel.

I. INTRODUCTION
In an age where the process of industrialization and modernization is taking place all over the world today, the demand for energy is enormous.Internal combustion engines are widely used on machinery and equipment for economic development.Due to higher energy conversion efficiency and cheaper fuel use, diesel engines are always preferred as a driving force on generators, construction machines, agricultural machinery, and heavy industry, and especially on road and sea transport vehicles.However, emissions from these vehicles also account for a large proportion of environmental pollution [1]- [3].
Today, with the rapid pace of development of vehicles, especially in urban areas, serious air pollution is caused by exhaust from automobile engines [4]- [6].Environmental pollution is one of the most pressing issues in many countries today.From the demand for such large fuel use, along with the constantly volatile fuel prices, the supply is exhausted and emissions of air pollution due to increasingly serious vehicles are harmful to human health and ecological environment [7]- [9].There are many measures to improve the efficiency, fuel economy, emission reductions for diesel engines such as: Using alternative or optimized fuel structures (intelligent air distribution, exhaust gas recirculation), engine pressure boost, combustion technology due to homogeneous composite compression, electronic fuel supply control system) [10]- [15].However, these innovative technologies come with high cost and are only suitable for new engine designs, difficult to interfere with existing engines.Fuel consumption in the world is shown in Fig. 1.Therefore, in order to solve urgent problems for currently circulating engines, it has urged scientists to research and develop engines in general, especially using fuel additives to apply nanotechnology to save Fuel and reduce emissions of pollutants to ensure increasingly stringent environmental regulations [16]- [19].In recent years, seeking renewable and environmentally friendly energy sources is always a pressing issue of the whole world, because of the potential of reserves of traditional energy sources is decreasing, and exploitation costs and Processing of fossil fuel sources is increasing [20]- [22].Lignocelluloza biomass is a rich source of raw materials, suitable for industrial-scale production of alternative energy sources, because it can be exploited everywhere, the price is relatively low and the source of raw materials is born.From lignocellulose biomass, a wide range of basic chemicals or intermediate compounds can be obtained, such as ethanol, butanol, lactone or metylfuran and dimethylfuran.Furan compounds are considered as promising additives of engine fuel.One of the furan derivatives of interest is 2.5-dimethylfuran (DMF), which is insoluble in water used as a blending additive with fuel gasoline.DMF has a boiling temperature of about 94 oC, with a temperature of about 31.5 MJ L − 1 which is roughly equivalent to gasoline (about 35 MJ L − 1), and much higher than ethanol (about 23 MJ L − 1).The rapid development of industries in general, the transportation industry in particular leads to increasing demand for diesel fuel.According to the survey, fossil fuels account for 80% of the world's main Potential of Biomass Sources for Fural-Based Fuel Production in the Consideration as a Green Fuel Danh Chan Nguyen, and Van Huong Dong energy consumption, of which 58-66% is consumed by transport vehicles [23]- [25].In Asia-Pacific, the total demand for oil products will increase by an average of 1.6% per year from 2015-2035.In 2015, diesel use accounted for 30% compared to other fossil fuels, and remained stable until 2035.Therefore, in order to solve urgent problems for currently circulating engines, it has urged scientists to research and develop engines in general, especially using fuel additives to apply nanotechnology to save Fuel and reduce emissions of pollutants to ensure increasingly stringent environmental regulations.

II. POTENTIAL OF BIOMASS SOURCES FROM RICE STRAW
Currently, many provinces and cities nationwide have applied microbiological technology to disintegrate straw to make fertilizer.For example, people have applied microbial decomposition technology to make fertilizer.The results of using microbial organic fertilizer from agricultural residues have shown that the plants grow better than the control specimens of planting density, green, smooth, tall, strong and especially drought-resistant leaves.Processing fungi for plants.If using probiotics to create compost, reduce a large amount of input for farmers and improve soil to reduce environmental pollution.At the same time, create a safe and healthy agricultural product for the community, towards a quality safe rice brand.The harvested straw is collected by farmer households and gathered in a place convenient for incubation or collection at families.The use of probiotics to process straw for composting for safe rice production has made full use of agricultural straw after each rice harvest with biological products to create compost fertilizing for crops, improving soil, ensuring crop productivity, creating safe rice products with little residue or no residues of toxic chemicals in rice products, contributing to environmental protection and protection protecting public health [1]- [4], [7]- [9].
In theory, biomass can be transformed into biofuel with the help of bacteria that decompose them into useful chemicals.Such an application has been used in more than 30 countries worldwide to help convert corn, molasses and other crops into ethanol fuel, a form of biofuels.However, scientists still have not approached the source of rice straw to produce biofuel because bacteria cannot easily break down cellulose in straw, due to the complex physical and chemical structures that make up the type.This biomass.Now, Chinese scientists have developed a pre-treatment method for rice straw that increases its biofuel production potential.They mixed straw with alkaline water before allowing bacteria to ferment.Alkaline water makes straw more biodegradable [25].
This alkaline water technology also allows researchers to increase the yield of biogas, a mixture of methane fuel with carbon dioxide, up to 65%.Three pilot facilities using this technology have been built.The plan is to build concentrated biogas stations for towns to provide biofuel for households through underground pipelines.The residues of the remaining straw will be returned to make organic fertilizer irrigate the fields.According to the research team, this method will make rice straw completely recycled.
Although carbon dioxide will be produced in this process, causing a greenhouse effect, the team thinks that rice will reabsorb carbon dioxide from the air during growth.Potential transformation technologies for rice straw include direct heating, direct thermal generation, gasification and electricity generation (gas, steam turbine, fuel cell), gasification and production of methanol, rapid pyrolysis (flash Pyrolysis), acid hydrolysis and ethanol fermentation, co-firing.Only two of these technologies, thermal combustion and direct thermal production are commercialized.Other technologies such as direct burning and steam turbine generation are also capable of using rice straw, but these conventional technologies have very high production costs due to the small scale of the treatment process.Costs for high energy recovery devices.Gasification and power generation technologies (by gas engines, steam turbines and fuel cells) also need technical improvements as well as reduced costs for using straw as fuel [26], [27].
Co-firing technology is characterized by achieving a higher thermal value than the heat value of straw when burned alone.However, this technology still needs to be studied further in such areas as moisture content, ash content and the need to develop pre-treatment technology for rice straw before being burned in the furnace.

III. PRODUCTION OF FURAL-BASED FUEL FROM RICE STRAW
Vietnam has an abundance of rice straw annually.World studies in recent decades have shown that straw is a lignocellulose biomass source capable of converting into bioethanol -a promising renewable energy source.Therefore, research on bioethanol production is receiving the attention of researchers and managers in Vietnam.The three main steps in bioethanol production are pretreatment, hydrolysis and fermentation.In particular, pretreatment is a very important step [28], [29].The purpose of the pretreatment process is to alter the lignocellulose structure, making cellulose more accessible to enzymes, supporting subsequent hydrolysis of polymer carbohydrates into fermentable sugars.However, pretreatment is said to be one of the costliest steps in converting biomass to ethanol.Because the structure of lignocellulose materials is very complex, there are many criteria for evaluating their hydrolysis ability, including: contact surface and pore increase; lignin structure transformation and lignin removal; vascular polimer of hemicellulose and partially dissolve hemicellulose; the ability to break down the crystal structure of cellulose.To achieve these standards, the lignocellulose pretreatment step is not simple.

Fig 3. SEM of straw
There are many methods of pretreatment of lignocellulose materials.The selection of pre-treatment methods is mainly dependent on lignocellulose structure components of biomass.Among the pretreatment methods, alkali pretreatment compared to other pretreatment processes uses low temperature and pressure, even under normal conditions, and costs are not high compared to pre-treatment types and another reason.Several studies have suggested that alkaline hydrolysis is based on the process of saponification between intermolecular molecules hemicelluloses such as xylan and other components such as lignin.Kong's study showed that alkali pretreatment removed acetyl groups from hemicellulose (primarily xylose), thereby reducing enzyme space and improving carbohydrate hydrolysis.Bases such as calcium, potassium or sodium hydroxide (Ca(OH)2, KOH or NaOH) are often used in alkali pretreatment.The condition of pretreatment with these alkali is relatively simple but the reaction time can be prolonged.These alkali types have the ability to dissolve high lignin content, especially for biomass containing low lignin content such as softwood and grass stems.Furthermore, due to the uncomplicated treatment conditions, the formation of inhibitors for subsequent hydrolysis and fermentation steps such as furfural, HMF and organic acids is also limited.Another study that conducted pretreatment of biomass with high-temperature liquid ammonia also reduced lignin and hemicellulose content, while eliminating some unusual structural cellulose.Sodium carbonate (Na2CO3), a weak alkali, may also be a viable option for alkali pretreatment.Na2CO3 is relatively cheap, compared to the price of sulfuric acid, easily commercially produced and easily processed when discharged into the environment [30].Studies have shown that pretreatment with Na2CO3 improves the efficiency of sugar production.It acts as an alkaline catalyst, whose efficiency increases from the separation of ester bonds and glycosidic bonds in the cell wall network, and leads to changes in the lignin structure, amorphous cellulose and part of cellulose are not crystalline [31].In another study, ultrasound combined pretreatment and NaHCO3 were reported to improve the ability to dispose of waste in newsprint.
After surveying NaHCO3 concentration, select 4% NaHCO3 to investigate the effect of dry straw content of 2.5wt% -10wt% on money efficiency.The experiments were conducted at room temperature and stirred for 24 hours.From the results of straw fiber analysis after pretreatment, we have the following Table I [32]- [35]: According to the table above, the largest reduction in solid mass was 2.5 wt%, however, the concentration of xylan and glucan was highest; meanwhile, with a 10% straw content, the amount of reduction of xylan and glucan is quite small but the least amount of solid reduction means that the extract is hydrolysed quite a lot at this concentration.At straw content of 5 wt% and 7.5 wt% showed similar results in all 3 parameters and showed a more effective pretreatment effect at the other two straw contents but at 7.5 wt% for the reduction of glucan and xylan at least (5.5 wt%) [36].Therefore, to increase the enzymatic hydrolysis of cellulose, the straw content of 7.5wt% was selected to continue the survey for the following experiments [37].
Cellulose acetylation is usually carried out in the presence of strong acids such as sulfuric acid and perchloric acid.The results show that acetylation of cellulose is complete when inorganic acids are present strongly.Cellulose acetates with DS of 2.92 and 2.83 are obtainedby the presence of sulfuric acid and perchloric acid, respectively.Strong acidity (low pKa) of strong inorganic acids may be due to complete acetylation [38], [39].Catalytic performance of tungstic acid (H2WO4 or WO3•H2O) and phosphotungstic acid heteropolyacid were also examined.Almost no activity of tungstic acid is observed, possibly due to insolubility and acidity [40].It was found that phosphotungstic acid was also an active catalyst for acetylation of straw treated straw, which almost exhibited a catalytic performance compared to H2SO4 based on the yield of cellulose acetate.This can be attributed to the relatively strong Brønsted acid of phosphotungstic acid, which has a similar role to strong acid.However, both DS and DP values of cellulose acetate obtained with the presence of phosphotungstic acid are clearly lower than those obtained in the presence of strong inorganic acids.It can be seen that DS of 2.25 and DP of 225 are obtained under the same conditions, respectively [41], [42].These results indicate that acetylation of cellulose is significantly influenced by the acidity of the catalyst.The OH groups are partially replaced in the presence of phosphotungstic acid but are completely replaced by strong inorganic acids as catalysts.It is known that cellulose acetate of low DS value is soluble in common organic solvents such as acetone, which will be discussed in more detail later.
The dependence of the acetylation of straw treated on phosphotungstic acid intake was also investigated.The molar ratio of phosphotungstic acid to AGU varies in the range from 0.1 to 0.3.The DS values were almost constant at the initial stage but then one drop was observed with a molar ratio of over 0.15 [43].The DS and DP values decreased significantly to 1.43 and 179 with the 0.3 mol catalyst ratio for AGU, respectively.Both acidity and water content in the reaction system is enhanced by increasing the amount of phosphotungstic acid because of the hydration compound H3PW12O40 • 6H2O is used as a catalyst [44].It is believed that an increase in acidity is useful to improve the acetylation of cellulose, thus increasing the yield observed.Cellulose acetate chains can easily break down the presence of large amounts of water, resulting in a decrease in DP values [45].The DS values of cellulose acetate obtained in the presence of phosphotungstic acid indicate that the products mainly include cellulose diacetate.
Once the reaction conditions have been determined in the water / acetone environment, these conditions (125 gL-1 of fructose, 180 ° C and 1% H3PO4) are used to test other solvents (2 -butanol and ethyl ether), and also change the mass ratio of both phases (Vorg: Vaq = 1: 1 and 2: 1) [46].
The result of fructose separation with different solvents, as well as with only one phase of water is shown in Fig. 4. The conversion of frucose to almost 100% in all reactions.The benefit of using organic solvents, even when it is completely mixed with water, is evident when HMF yield analysis: in water environments, HMF yield is only 34%, and with mixed Organic water / mixture mixture increased by 50-60% (when the volume ratio is 1: 1) [47].Therefore, the presence of organic solvents in the reaction process reduces the likelihood of HMF exposure to water leading to HMF depletion and rehydration.1: 1 ratio between ether: water is bi-phasic (very low solubility of water in water) and very low coefficient of division, only 0.3, shows poor displacement of HMF to the organic phase.The yield of HMF is similar for all three solvents when the volume ratio is 1: 1, with a slightly lower ethyl ether value.HMF yield with acetone is 55%, close to the level obtained when using 2-butanol (59%) [44].Acetone helps produce furanoid forms from fructose, from which a large amount of HMF is obtained in the reaction.The ability to select HMF was higher when using 2-butanol than acetone, but the tests were only performed with saturated aqueous phase with NaCl [48].When Vorg volume ratio: Vaq is increased to 2: 1, HMF yield is nearly the same as the 1: 1 ratio in the case of acetone and 2-butanol, indicating that the solvents are completely mixed.The increase in organic matter content does not increase HMF formation.However, when using ethyl ether at a ratio of 2: 1, there is humins formation and HMF yield is only 27%, with a partition coefficient of 0.4 [36].The use of very low boiling point solvents is not appropriate in biphasic systems, since the solvent prioritizes the vapor phase in the reaction, which has the undesirable effect of HMF extraction from the aqueous phase.
To achieve the highest output, the reaction conditions need to be optimized by changing the temperature and reaction time.The reaction test is performed at different temperatures (200-270°C) in the presence of phosphoric acid.
It is clear that temperature has a significant impact on hydrolysis and / or water separation of glucose, fructose and cellulose.The glucose conversion process was raised from 43 to 92% when the temperature increased from 200 to 270 0 C. HMF productivity increases gradually as the temperature increases, and the yield corresponds to a 10% catalyst peak at 220 and 230 0 C [42].At temperatures higher than 2300C, HMF yield gave the opposite result, although glucose metabolism still increased slightly.Fructose transformation showed a high value (> 85%) for all study temperature levels.HMF productivity drops sharply from 29% to 0% when temperatures increase from 200 to 270°C, and a large number of brown insoluble products are formed, probably humins.Hydrolysis of cellulose depends heavily on temperature.High temperatures can enhance the conversion of cellulose into glucose.However, the decomposition side effect of glucose may also occur and speed up with increasing temperature [45].By increasing the temperature, the product yield from cellulose hydrolysis / separation was enhanced, reaching a maximum at 230 0 C. When the reaction temperature rises above 230 0 C, yield of HMF begins to decrease and intermediates such as glucose are not detected.These results are consistent with the transformation of glucose and fructose described above.Higher temperatures can accelerate chemical reactions, while unwanted side effects occur at the same time.Under current research conditions, it was discovered that humins occur in reactions at higher temperatures [49].In addition, carboxylic acids and aldehydes were partially detected as confirmed by qualitative analysis of GS-MS.
The effect of reaction on hydrolysis and / or water separation of glucose, fructose and cellulose in the presence of phosphoric acid was studied under conditions of compressed hot water at 220, 200 and 230 0 C, increased glucose metabolism up regularly when reaction time increases, and greater than 90% at 30 minutes.However, HMF production decreased over long periods of time, due to successive decomposition of formic acid and levulinic as confirmed by GC-MS analysis.Fructose conversion showed high value (> 90%) at 0-30 minutes.HMF productivity increases with time extending from 0 (26%) to 5 minutes (29%) [50].Productivity reaches maximum at 5 minutes' time, and significantly decreases after that.
Effects of different types of catalysts on the process of water separation of sugar molecules (glucose and fructose) and hydrolysis / separation of cellulose were studied in detail in the condition of HCW (HCW: Hot compressed water).Sodium hydroxide and phosphoric acid were selected as representative acid catalysts in these experiments for comparison.With or without catalysts, fructose conversion is almost stable at 82-92%.Under current research conditions, fructose can be rapidly dehydrated and converted into furans, and thus the addition of sodium hydroxide and phosphoric acid only produces a small change effect in fructose conversion.However, HMF yield was highest at 29% when using phosphoric acid catalysts.The results showed that fructose's water separation reaction is much more developed than glucose catalyzed by both sodium hydroxide and phosphoric acid.In glucose conversion, selective furan derivatives are greatly enhanced when using catalysts [51].This behavior can be described for their structural change in reaction.Glucose forms a very stable ring structure, so that the part of the open chain is formed in the solution, and the bonding speed is slow.On the other hand, the less stable ring structure of fructose has resulted in higher open chains, and therefore relatively high adhesion rates.Strictly speaking, glucose undergoes a polymerization process with fructose and then fructose is converted to HMF via a dehydration step.The opening of the ring will have a high energy barrier, especially when no catalyst is used, and perhaps considered a step in determining the speed in converting the overall glucose to HMF.Using catalysts will help reduce the activation energy needed.HMF production is therefore higher with the use of catalysts with fructose as the starting material.
There are many research papers showing the separation of cellulose and lignin from wheat straw by using a solvent mixture of toluene/ethanol to remove paraffin (pretreatment) before extraction.We compared pretreatment methods and were not pretreated before alkali treatment, but the extraction of yield and lignin or cellulose properties was no different.Therefore, we propose the process of separating cellulose and lignin from rice straw without pretreatment of paraffin to improve economic efficiency, reduce environmental pollution and develop potential industrial applications [52].Straw is poorly digested by ruminants because of its high cell wall content.Alkali treatment breaks down cell walls by dissolving hemicellulose, lignin and silica, by hydrolyzing uric acid esters and acetic acid, and by making cellulose.Furthermore, lye breaks the α-ether bond between lignin and hemicellulose and ester bonds between lignin and hydroxycinnamic acids such as p-coumaric acid and ferulic acid [23].More importantly, alkaline treatment is a promising approach that does not affect the environment.Through this process, lignocellulose can be divided into lignin, hemicellulose and cellulose, which is the raw material for valuable products.A process of lignin extraction from wheat straw with 0.5M of KOH at 35 ° C for 2.5 hours, but yield of only 43.9% was detected in [24].The separation of lignin from straw with 1M of NaOH solution at 30 ° C. The yield was only 68.3% for a long time of 18 hours [25].In this study, alkaline solutions with high concentrations of 2M of NaOH, high temperatures of 90 ° C, and ultrasonic irradiation were used to increase lignin separation efficiency and reduce separation time.Treatment of straw with 2M of NaOH without ultrasonic irradiation at 90 ° C for 1.5 hours and ultrasonic irradiation for 10, 20, 30 and 40 minutes of lignin (72.8%, 72.9%, 78.6%, 84.7%, and 84.9%.) [52], [53].

IV. CONCLUSION
Lignocelluloza biomass is a rich source of raw materials, suitable for industrial-scale production of alternative energy sources, because it can be exploited everywhere, the price is relatively low and the source of raw materials is born.From lignocellulose biomass, a wide range of basic chemicals or intermediate compounds can be obtained, such as ethanol, butanol, lactone or metylfuran and dimethylfuran.Furan compounds are considered as promising additives of engine fuel.One of the furan derivatives of interest is 2.5dimethylfuran (DMF), which is insoluble in water used as a blending additive with fuel gasoline.DMF has a boiling temperature of about 94 o C, with a temperature of about 31.5 MJ L −1 which is roughly equivalent to gasoline (about 35 MJ L −1 ), and much higher than ethanol (about 23 MJ L −1 ).Our country is rich in lignocellulose materials, so it is possible to convert these agricultural by-products into useful, valuable products to meet consumer and industrial needs such as fuel additives.Research direction has scientific and practical significance.However, the synthesis of dimethylfuran additives still faces many difficulties due to technological problems.Thus, the main existence of the product lies in the use of additives for internal combustion engines to have the most realistic assessments.Therefore, the implementation of dimethylfuran fuel additives from biomass used for internal combustion engines to reduce fuel consumption and toxic emissions is extremely significant real and meaningful science.Although there have been many studies and applications of DMF in internal combustion engines, their adaptability and efficiency compared with traditional fuels still require extensive research and experimentation to allow DMF to replace fuel transmission in the future.

Fig. 1 .
Fig. 1.Fuel consumption in the world to 2040

Fig. 2 .
Fig. 2. Potential of rice straw as biomass source

TABLE I :
RICE STRAW FIBER ANALYSIS AFTER PRETREATMENT