Fernando S - 2006 - Biorefineries-current Status, Challenges and Future Direction

Biorefineries: Current Status, Challenges, and Future DirectionSandun Fernando,* Sushil Adhikari, Chauda Chandrapal, and Naveen Murali

Department of Agricultural and Biological Engineering, Mississippi State UniVersity,Mississippi State, Mississippi 39762

ReceiVed March 2, 2006. ReVised Manuscript ReceiVed May 16, 2006

Conventional resources mainly fossil fuels are becoming limited because of the rapid increase in energydemand. This imbalance in energy demand and supply has placed immense pressure not only on consumerprices but also on the environment, prompting mankind to look for sustainable energy resources. Biomass isone such environmentally friendly renewable resource from which various useful chemicals and fuels can beproduced. A system similar to a petroleum refinery is required to produce fuels and useful chemicals frombiomass and is known as a biorefinery. Biorefineries have been categorized in three phases based on theflexibility of input, processing capabilities, and product generation. Phase I has less or no flexibility in any ofthe three aforementioned categories. Phase II, while having fixed input and processing capabilities, allowsflexibility in product generation. Phase III allows flexibility in all the three processes and is based on theconcept of high-value low-volume (HVLV) and low-value high-volume (LVHV) outputs. This paper reviewsthe concept of biorefinery, its types, future directions, and associated technical challenges. An approach ofstreamlining biorefineries with conventional refineries in producing conventional fuels is also presented.Furthermore, twelve platform chemicals that could be major outputs from an integrated biorefinery are alsodiscussed.

1. Introduction

Currently, the energy requirements of the world are largelymet by fossil fuels. The limited deposits of these fossil fuelscoupled with environmental problems, such as greenhouse gases,have prompted mankind to look for sustainable resources asalternatives to meet the increasing energy demand. Biomass isone of the few resources that has the potential to meet thechallenges of sustainable and green energy systems. Biomassis a plant matter of recent (nongeologic) origin or materialderived there from and could be used to produce various usefulchemicals and fuels.1 A system similar to a petroleum refinerycalled a biorefinery has been proposed to produce usefulchemicals and fuels from biomass. According to NationalRenewable Energy Laboratory (NREL), a biorefinery is afacility that integrates conversion processes and equipments toproduce fuels, power, and chemicals from biomass.2 To achievethe goals of sustainable development, biorefineries have to playa dominant role in the coming millennia. An effort has beenmade in this paper to review the biorefinerys development todate and its future directions.

2. The Biorefinery Concept

The concept of producing products from agricultural com-modities (i.e., biomass) is not new. However, using biomass asan input to produce multiple products using complex processingmethods, an approach similar to a petroleum refinery where

fossil fuels are used as input, is relatively new. Biomass consistsof carbohydrates, lignin, proteins, fats, and to a lesser extent,various other chemicals, such as vitamins, dyes, and flavors.3The goal of a biorefinery is to transform such plentiful biologicalmaterials into useful products using a combination of technolo-gies and processes. Figure 1 describes the elements of abiorefinery in which biomass feedstocks are used to producevarious useful products such as fuel, power, and chemicals usingbiological and chemical conversion processes.

The main goal of a biorefinery is to produce high-value low-volume (HVLV) and low-value high-volume (LVHV) productsusing a series of unit operations. The operations are designedto maximize the valued extractibles while minimizing the wastestreams by converting LVHV intermediates into energy. Thehigh-value products enhance the profitability, while the high-volume fuels help to meet the global energy demand. The powerproduced from a biorefinery also helps to reduce the overall

* To whom correspondence should be addressed. Phone: +1 662 3253282. Fax: +1 662 325 3853. E-mail: [email protected].

(1) Lynd, L. R.; Jin, H.; Michels, J. G.; Wyman, C. E.; Dale, B.Bioenergy: background, potential, and policy. Available from http://rmtools.org/ref/Lynd_et_al_2002.pdf (June 24, 2005).

(2) National Renewable Energy Laboratory. Conceptual biorefinery.Available from http://www.nrel.gov/biomass/biorefinery.html (August 1,2005).

(3) Askew, M. The biorefinery concept. Available from http://europa.e-u.int/comm/research/energy/pdf/renews3.pdf (August 1, 2005).

Figure 1. Simple three-step biomass-process-products procedure.4

1727Energy & Fuels 2006, 20, 1727-1737

10.1021/ef060097w CCC: $33.50 2006 American Chemical SocietyPublished on Web 06/27/2006

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cost.2 In contrast to a petroleum refinery, a biorefinery usesrenewable resources and produces fuels and chemicals thatcontribute less to environmental pollution. Table 1 depicts theincrease in biobased products sales worldwide from 1983 to1994. This clearly shows there is a growing interest in biobasedproducts. Similarly, Table 2 depicts the United States targetsfor biobased products in the selected years.

3. Types of Biorefineries

Three types of biorefineries known as phase I, II, and III havebeen described by Kamm et al.6 and Van Dyne et al.7 A phase

I biorefinery plant has fixed processing capabilities and usesgrain as a feedstock. A dry mill ethanol plant, illustrated inFigure 2, is an example of a phase I biorefinery which producesa fixed amount of ethanol, other feed products, and carbondioxide and has almost no processing flexibility.6,7

A process involving current wet milling technology couldbe considered a phase II biorefinery which uses grain feedstockas input similar to dry milling. However, it has the capability

(4) Sokhansanj, S.; Cushman, J.; Wright, L. Collection and delivery ofbiomass for fuel and power production. Available from http://www.ten-nesseebiomass.com/storage.php (June 27, 2005).

(5) Biobased Industrial Products: Research and CommercializationPriorities; The National Academies Press: Washington, DC, 2000.

(6) Kamm, B.; Kamm, M. Principles of biorefinery. Appl. Microbiol.Biotechnol. 2004, 64, 137-145.

(7) Dyne, D. L. V.; Blase, M. G.; Clements, L. D. A strategy for returningagriculture and rural America to long-term full employment using biomassrefineries. In PerspectiVes on New Crops and New Uses; Janick, J., Ed.;ASHS Press: Alexandria, VA, 1999.

Figure 2. Dry mill ethanol process plant.8

Figure 3. Representation of whole-crop biorefinery process and products.6

1728 Energy & Fuels, Vol. 20, No. 4, 2006 Fernando et al.

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to produce various end products and far more processingflexibility6,7 depending upon a product demand, prices, andcontract obligations. The typical products are starch, high-fructose corn syrup, ethanol, and corn oil. A phase III, the mostdeveloped biorefinery, uses a mix of biomass feedstocks and

yields an array of products by employing combination oftechnologies.6 It allows a mix of agricultural feedstocks, hasthe ability to use various types of processing methods, and hasthe capability to produce a mix of higher-value chemicals whilecoproducing ethanol.9 It is based on both the HVLV and LVHVprinciples. The Phase III biorefineries, namely, whole-crop,green, and lignocellulose feedstock (LCF) biorefineries, are stillin research and development.6

3.1. Whole-Crop Biorefinery. A whole-crop biorefineryprocesses and consumes the entire crop to obtain useful products.Raw materials such as wheat, rye, triticale, and maize can beused as input in the feedstock in the unit operations of a whole-crop biorefinery as depicted in Figure 3. The process ofconverting biomass into energy is initiated by mechanicalseparation of biomass into different components that are thentreated separately. Biomass is the starting material for theproduction of syngas where syngas can be used as the basicmaterial for the synthesis of fuels and methanol using the FischerTropsh process.6 Corn either can be used directly after grindingto meal or can be converted to starch. Further processing canbe carried out as follows: (i) breaking up, (ii) plasticization,(iii) chemical modification, and (iv) biotechnological conversionvia glucose.

3.2. Green Biorefinery. A green biorefinery is a multiproductsystem which handles its refinery cuts, product, and fractions

(8) Lasure, L. L.; Zhang M. Bioconversion and biorefineries of the future.Available from http://www.pnl.gov/biobased/docs/biorefineries.pdf (August1, 2005).

(9) Tyson, K. S.; Bozell, J.; Wallace, R.; Petersen, E.; Moens, L. Biomassoil analysis: research needs and recommendations. NREL Technical Report.Available from http://www.eere.energy.gov/biomass/pdfs/34796.pdf (August1, 2005).

Figure 4. Representation of green biorefinery process and products.6

Table 1. Worldwide Sales of Biotechnology Products, 1983 and1994a

1983 ($ millions) 1994 ($ millions)fuel and industrial ethanol 800 1500high-fructose syrups 1600 3100citric acid 500 900monosodium glutamate 600 800lysine 200 700enzymes 400 1,000specialty chemicals 1300 3000total 5400 11 000

a Table excludes pharmaceutical products.5

Table 2. United States Biobased Industry Targets5

biobased production levelsbiobasedproduct current level

future targetintermediate (2020)

future targetultimate (2090)

liquid fuelsa 1-2% 10% up to 50%organic

chemicalsb10% 25% >90%

materialsc 90% 95% 99%a Large-scale production of biobased ethanol is a long-term possibility

and the projection assumes advanced technologies are in place for processinglignocellulosic materials. b Include oxygenated chemicals such as butanolor butyl butyrate that can be processed into other intermediate and specialtychemicals traditionally dependent on fossil fuel feedstocks. c Includetraditional forest products such as lumber, as well as novel biopolymers,such as bioplastics. Many new products in this market will be high-valuematerials that cannot be produced from petroleum feedstocks.

Biorefineries Energy & Fuels, Vol. 20, No. 4, 2006 1729

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in accordance with the physiology of the corresponding plantmaterial as described by Kamm et al.6 and illustrated in Figure4. A green biorefinery uses natural wet feedstocks derived from

untreated products, such as grass, green plants, or green cropsas inputs, which are produced in large quantities in green plants.The first step of the refinery is to treat the green biomass

Figure 5. Representation of LCF biorefinery process and products.6

Figure 6. Sugar-lignin platform biorefinery.12


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substances in their natural form using wet-fractionation toproduce a fiber-rich press cake and a nutrient-rich green juice.The press cake contains cellulose, starch, valuable dyes andpigments, crude drugs, and other organics, whereas the greenjuice includes proteins, free amino acids, organic acids, dyes,enzymes, hormones, other organic substances, and minerals. Thepressed cake can be also used for the production of green feedpellets, as a raw material for the production of chemicals, suchas levulinic acid, and for conversions to syngas and syntheticfuels.6

3.3. Lignocellulose Feedstock (LCF) Biorefinery. LCFconsists of three basic chemical fractions: (i) hemicellulose,five carbon sugar polymers, (ii) cellulose, six carbon glucosepolymers, and (iii) lignin, phenol polymers.9 A LCF biorefineryas depicted in Figure 5 uses hard fibrous plant materialsgenerated by lumber or municipal wastes. Initially, plant materialis cleaned and broken down into the three fractions (hemicel-lulose, cellulose, and lignin) via chemical digestion or enzymatichydrolysis. Hemicellulose and cellulose can be produced byalkaline (caustic soda) and sulfite (acidic, bisulfite, alkaline, etc.).Lignin in plant materials is broken down with enzymes such asligninases, lignin peroxidases, laccases, and xylanolytic en-zymes. The sugar polymers (hemicellulose and cellulose) areconverted to their component sugars (Figure 5) through hy-drolysis. In the case of hemicellulose, it consists of short, highlybranched chains of sugars. In contrast to cellulose, which is a

polymer of only glucose, a hemicellulose is a polymer of fivedifferent sugars. It contains five-carbon sugars (usually D-xyloseand L-arabinose), six-carbon sugars (D-galactose, D-glucose, andD-mannose), and uronic acid. The hydrolysis process of hemi-cellulose results in aforementioned sugars. The followingchemical reactions provide a general overview of the conver-sions that take place in a LCF biorefinery.

The xylose fraction from hemicellulose is important becauseit can be converted to furfural which is one of the startingmaterials for nylon 6.6 Furthermore, furfural has many uses: itcan be used in the refining of motor oils, as a precursor of certainplastics, and as cleaning agents in liquid fuels.

The hydrolysis of cellulose to glucose can be carried out eitherby enzymatic processing or chemical processing7 which pro-duces useful products, such as ethanol, acetic acid, acetone,butanol, succinic acid, and other fermentation products. Al-though the hemicellulose and cellulose fractions have numeroususes, it is not yet the case for lignin. Currently, lignin has limiteduses such as an adhesive or binder and as a fuel for directcombustion. However, the lignin scaffold has tremendouspotential to produce various forms of monoaromatic hydrocar-bons, which, if isolated in an economically efficient way, couldadd significant value to the primary LCF process. It should benoticed that there are no obvious, natural enzymes to split thenaturally occurring lignin into its basic monomers as easily asis possible for naturally formed polymeric carbohydrates orproteins.6 The LCF plant in Missouri produces around 180 106 tons of ethanol and 323 103 tons of furfural annuallyfrom daily feedstock consumption of 4000 tons.7 If substantial

Table 3. Composition of Bio-oil Compounds, Part Itype compound wt % type compound wt %

acids formic (methanoic) 0.3-9.1 nitrogen compounds ammoniaacetic (ethanoic) 0.5-12 methylamine

0.1-1.8 pyridinehydroxyacetic 0.1-0.9 methyl pyridine2-butenic (crotonic) alcohols methanol 0.4-2.4butanoic 0.1-0.5 ethanol 0.6-1.4pentanoic (valeric) 0.1-0.8 2-propene-1-ol2-Me butenoic isobutanol4-oxypentanoic 0.1-0.4 3-methyl-1-butanolhexanoic (caproic) 0.1-0.3 furans furan 0.1-0.3benzoic 0.2-0.3 2-methyl furan 0.1-0.2heptanoic 0.3 furfural 0.1-1.1

esters methyl formate 0.1-0.9 3-methyl-2(3h)furanone 0.1methyl acetate furfural alcohol 0.1-5.2methyl propionate furoic acid 0.4butyrolactone 0.1-0.9 methyl furoatemethyl crotonate 5-methylfurfural 0.1-0.6methyl n-butyrate 5-OH-methyl-2-furfural 0.3-2.2valerolactone 0.2 dimethyl furanangelicalactone 0.1-1.2 guaiacols 2-methoxy phenol 0.1-1.1

aromatics methyl valerate 4-methyl guaiacol 0.1-1.9benzene ethyl guaiacol 0.1-0.6toluene eugenol 0.1-2.3xylenes isoeugenol 0.1-7.2naphthalene 4-propylguaiacol 0.1-0.4phenanthrene acetoguiacone 0.8fluoranthenechrysene

Figure 7. Conceptual map of SPB and syngas platform-basedbiorefinery.2

lignocellulose + H2O ) lignin + cellulose + hemicellulose

hemicellulose + H2O ) xylose

xylose (C5H10O5) + acid catalyst )furfural (C5H4O2) + 3H2O

cellulose (C6H10O6) + H2O ) glucose (C6H12O6)


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microbial conversion of glucose can be carried out, it can beused as an alternative route 6,10,11 for the petrochemicallyproduced substances, such as hydrogen, methane, propanol, andacetone.

In a more modern approach, the U.S. Department of Energy/NREL have described conversion technologies for expandedbiomass based on the platforms because the basic technologywould generate base or platform chemicals from which industrycould make a wide range of fuels, chemicals, materials, and

power. Five platforms have been suggested: sugar platformbiorefineries (SPBs), thermochemical or syngas platform, biogasplatform, carbon-rich chains platform, and plant productsplatform. The sugar platform focuses on the fermentation ofsugars extracted from biomass feedstocks. The objective is tobiologically process the sugars to produce fuel, such as ethanol,or other building block chemicals. SPBs are closely related toLCF biorefineries in the conventional nomenclature. The unitoperation of a SPB is provided in Figure 6.

The thermochemical or syngas platform focuses on thegasification of the biomass feedstocks. This approach convertsthe solid biomass into gaseous and liquid fuels by mixing itwith limited oxygen prior to combustion. Various componentsproduced through this process can be separated into fuels or

(10) Zeikus, J. G.; Jain, M. K.; Elankovan, P. Biotechnology of succinicacid production and markets for derived industrial products. Appl. Microbiol.Biotechnol. 1999, 51, 545-552.

(11) Willke, T.; Vorlop, K. D. Industrial bioconversion of renewableresources as an alternative to conventional chemistry. Appl. Microbiol.Biotechnol. 2004, 66, 131-142.

Figure 8. Schematic of an integrated biorefinery.13

Table 4. Composition of Bio-oil Compounds, Part IItype compound wt % type compound wt % type compound wt %

ketones acetone 2.8 aldehydes formaldehyde 0.1-3.3 sugars levoglucosan 0.4-1.42-butenone acetaldehyde 0.1-8.5 glucose 0.4-1.32-butanone (MEK) 0.3-0.9 2-propenal (acrolein) 0.6-0.9 fructose 0.7-2.92,3-butandione 2-butenal trace D-xylose 0.1-1.4cyclopentanone 2-methyl-2-butenal 0.1-0.5 D-arainose 0.12-pentanone pentanal 0.5 cellobiosan 0.6-3.23-pentanone phenols phenol 0.1-3.8 1,6-anhydroglucofuranose 3.12-cyclopentenone 2-methyl phenol 0.1-0.6 4-methoxy catechol 0.62,3-pentenedione 0.2-0.4 3-methyl phenol 0.1-0.4 miscellaneous

oxygenateshydroxyacetaldehyde 0.9-13

3-Me-2-cyclo-penten2ollone 0.1-0.6 4-methyl phenol 0.1-0.5 acetol (hydroxyacetone) 0.7-7.4Me-cyclopentanone 2,3-dimethyl phenol 0.1-0.5 methylal2-hexonone 2,4-dimethyl phenol 0.1-0.3 dimethyl acetalmethylcyclohexanone 2,6-dimethyl phenol 0.1-0.4 acetyloxy-2-propanone 0.82-Et-cyclopentanone 0.2-0.3 3,5-dimethyl phenol 2-OH-3-Me-2-cyclopentene-1-one 0.1-0.5dimethlycyclopentenone 0.3 2-ethyl phenol 0.1-1.3 methyl cyclopentenolone 0.1-1.9trimethylcyclopentenone 0.1-0.5 2,4,6-TriMe phenol 0.3 1-acetyloxy-2-propanone 0.1trimethylcyclopentenone 0.2-0.4 1,2-DiOH benzene 0.1-0.7 2-methyl-3-hydroxy-2-pryrone 0.2-0.4

syringols 2,6-DiOMe phenol 0.7-4.8 1,3-DiOH benzene 0.1-0.3 2-Methoxy-4-methylanisole 0.1-0.4methyl syringol 0.1-0.3 1,4-DiOH benzene 0.1-1.0 4-OH-3-methoxybenzaldehyde 0.1-1.14-ethyl syringol 0.2 alkenes 2-methyl propene maltolpropyl syringol 0.1-1.5 dimethyl

cyclopentene0.7

syringal dehyde 0.1-1.5 R-pinene4-propenyl syringol 0.1-0.3 dipentene


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valuable chemicals. NRELs main focuses are on the SPB andsyngas platforms. The concept of these two biorefineryplatforms is described in Figure 7.

The biogas platform is a widely used technology particularlyin developing countries for producing cooking gas. This platformdecomposes biomass with natural microorganisms in closedtanks known as anaerobic digesters. The process producesmethane and carbon dioxide. The carbon-rich chains platformuses plant oils, such as soybean, corn, palm, and canola oils,which are presently used for food and chemical production.Transesterification of the vegetable oil or animal fat producesfatty acid methyl esters, commonly known as biodiesel. Biodie-sel is already in use as an important commercial air-emissionreducing additive or substitute for petroleum diesel. Selectivebreeding and genetic engineering can be used to develop plantstrains that produce greater amounts of desirable feedstocks,chemicals, or even compounds that the plant does not naturallyproduce. The intention is to perform the biorefining in thebiological plant itself rather than in an industrial plant. Thisapproach is known as the plant products platform.

3.4. Integrated Biorefinery. The biorefinery types that wediscussed previously are based on one conversion technologyto produce various chemicals. A biorefinery is a capital-intensiveproject, and when it is based on just one conversion technology,as is the case for the previously described biorefineries, itincreases the cost of outputs (or products) generated from suchbiorefineries. Hence, several conversion technologies (thermo-chemical, biochemical, etc.) are combined together to reducethe overall cost, as well as to have more flexibility in productgeneration and to provide its own power. Figure 8 provides aschematic of an integrated biorefinery. Three different platforms,namely: thermochemical, sugar, and nonplatform or existingtechnologies are integrated. An integrated biorefinery producesvarious products, which include electricity produced fromthermochemical and bioproducts from the combination of sugarand other existing conversion technology platforms.

An emerging concept in the biorefinery arena is conversionof bio-oil, the product from biomass pyrolysis, which could berouted via a conventional petrochemical refinery (Figure 8) togenerate various chemicals. The advantage of this route is thatall necessary infrastructures for the separation and purificationof products generated are already in place. This concept makesperfect sense since most petroleum refineries are well equippedto handle variable feedstock with the assumption that no twobatches of crude oil are the same.

Tables 3 and 4 give the composition of bio-oil compounds.Bio-oil chemical properties vary with the feedstock but woodybiomass typically produces a mixture of 30% water, 30%phenolics, 20% aldehydes and ketones, 15% alcohols, and 10%miscellaneous compounds.14 A process known as hydrodeoxy-genation (HDO) could be applied to replacing oxygen byhydrogenation of the raw bio-oils. After several HDO treatmentsteps the bio-oil could be transformed into a liquid hydrocarbonwith properties similar to those of petroleum crude oil.15 Thedeoxygenated bio-oils can potentially be refined in existingpetroleum refineries, with only minor adjustments to the current

petroleum industry refinery infrastructure that is set up forhydrodesulfurization (HDS) process.16 HDO treatment of bio-oils with metallic catalysts, such as sulfated Co, Mo, W, or Ni,have been adopted from the petroleum industry.16-25 It has beenshown that a two-stage process is required.17,26 The first stageapplies a mild hydrogenation at relatively low temperaturesbelow about 270 C. Full HDO of bio-oils requires temperaturesabove 300 C which results in polymerization of the highlyoxygenated compounds in raw bio-oils.27

It is also important to standardize the quality requirementsof biorefinery products at the onset of this technology tominimize variability. Such standardization will help focus futureresearch to attain products with specific quality. As an example,it will be helpful for bio-oil researchers to know the minimumqualities to target if bio-oil is to be routed through a petroleumrefinery. Identifying these minimum qualities is a challenge,especially, because of the multidisciplinary nature of the subjectand should be done in close collaboration with petroleumengineers, bioenergy engineers, chemists, and biologists.

As with petrochemical refineries, the main objective of thebio-oil-based biorefinery is to produce multiple products,including higher-value chemicals, as well as fuels and power.Hence, it is important to look at the value-added chemicalsproduced from the integrated biorefinery, which economicallyand technically support the production of fuel and powerproduced from these refineries. NREL and PNNL (PacificNorthwest National Laboratory) researchers carried out anexhaustive study to identify valuable sugar-derived chemicalsand materials that could serve as an economic driver to theintegrated biorefinery.28 Increased productivity, lower productioncost, and efficiency could be achieved by employing operations

(12) National Renewable Energy Laboratory. Available from http://www.eere.energy.gov/biomass/pdfs/sugar_enzyme.pdf (August 1, 2005).

(13) Energy Efficiency and Renewable Energy, Office of the BiomassProgram. Multiyear Analysis Plan (FY04-FY08). (August 15, 2005).

(14) Bridgewater, A.; Czernik, C.; Diebold, J.; Mekr, D.; Radlein, P.Fast Pyrolysis of Biomass: A Handbook; CPL Scientific PublishingServices, Ltd: Newbury, U.K., 1999; p 188.

(15) Scholze, B. Long-term stability, catalytic upgrading, and applicationof pyrolysis oilssimproving the properties of a potential substitute for fossilfuels. Dissertation, Department of Physical Chemistry, University ofHamburg, Hamburg, Germany, 2002.

(16) Bridgewater, A. v.; Cottam, M. L. Opportunities for biomasspyrolysis liquids production and upgrading. Energy Fuels 1992, 6, 113-120.

(17) Baker, E. G.; Elliott, D. C. Catalytic hydrotreating of biomass-derived oils. In Pyrolysis Oils from Biomass; Soltes, E. J., Milne., T. A.,Eds.; American Chemical Society Symposium Series 376; AmericanChemical Society: Washington, DC, 1988; p 353.

(18) Centeno, A.; David, O.; Vanbellinghen, C.; Maggi, R.; Delmon, B.Behaviour of catalysts supported on carbon in hydrodeoxygenation reactions.In DeVelopments in Thermochemical Biomass ConVersion; Bridgewater,A. V., Boocock, D. G. B., Eds.; Blackie Academic and Professional:London, 1997; Vol. 1, p 1648.

(19) Conti, L.; Scano, G.; Boufala, J.; Mascia, S. Bio-crude oil hy-drotreating in a continuous bench-scale plant. In DeVelopments in Ther-mochemical Biomass ConVersion; Bridgewater, A. V.; Boocock, D. G. B.,Eds.; Blackie Academic and Professional: London, 1997; Vol. 1, p 1648.

(20) Elliot, D. C.; Schiefelbein, G. F. Liquid hydrocarbon fuels frombiomass. Am. Chem. Soc., DiV. Fuel Chem. 1989, 34 (4), 1160-1166.

(21) Ferrari, M.; Delmon, B.; Grange, P. Influence of the impregnationorder of molybdenum and cobalt in carbon supported catalysts forhydrodeoxygenation reactions. Carbon 2002, 40, 497-511.

(22) Oasmaa, A.; Boocock, D. G. B. The catalytic hydrotreatment ofpeat pyrolysate oils. Can. J. Chem. Eng. 1992, 70, 294-300.

(23) Puente, G.; Gil, A.; Pis, J. J.; Grange, P. Effects of support surfacechemistry in hydrodeoxygenation reactions over CoMo/activated carbonsulfided catalysts. Langmuir 1999, 15, 5800-5806.

(24) Zhang, S. P.; Yan, Y. J.; Ren, Z.; Li, T. Study of hydrodeoxygenationof bio-oil from the fast pyrolysis of biomass. Energy Sources 2003, 25,57-65.

(25) Czernik, S.; Maggi, R.; Peacoke, G. V. C. Review of methods forupgrading biomass-derived fast pyrolysis oils. In Fast Pryolysis of Biom-ass: A Handbook; Bridgewater, A. V., Ed.; CPL Press: Newbury, U.K.,2002; Vol. 2, p 425.

(26) Gagnon, J.; Kaliaguine, S. Catalytic hydrotreatment of vacuumpyrolysis oils from wood. Ind. Eng. Chem. Res. 1988, 27 (10), 1783-1788.

(27) Elliott, D. C.; Neuenschwander, G. G. Liquid fuels by low-severityhydrotreating of biocrude. DeV. Thermochem. Biomass ConVers. 1996, 1,611-621.


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that lower the overall energy intensity of the biorefinerys unitand drive down all production costs by maximizing the use ofall feedstock components, byproducts and waste streams,

economies of the scale, common processing operations, materi-als, and equipment. Details of some of the important value-added chemicals have been reviewed in a paper publishedelsewhere.28 The NREL and PNNL study has reduced list of300 initially selected candidates to 30 potential candidatesthrough an iterative process based on the petrochemical modelusing building blocks, chemical data, known market data,properties, performance of the potential candidates, and the priorindustry experiences of the PNNL and NREL team. The list ofthese 30 potential candidates was further reduced to 12 byevaluating the potential markets for the building blocks and theirderivatives and the technical complexity of the synthesispathway.

(28) Aden, A.; Bozell, J.; Holladay, J.; White, J.; Manheim, A. Top ValueAdded Chemicals from Biomass; Pacific Northwest National Laboratoryand National Renewable Energy Laboratory: Richland, WA, 2004; p 76.

Table 5. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Four Carbon

1,4-Diacids (succinic, furmaric, and malic acid)a

a Family 1, reduction; family 2, reductive aminations; family 3, directpolymerization.

Table 6. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of 2,5-Furan

Dicarboxylic Acid (FDCA)a

a Family 1, reduction; family 2, direct polymerization.

Table 7. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of 3-Hydroxy

Propionic Acid (3-HPA)a

a Family 1, reductions; family 2, dehydrations.

Table 8. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Aspartic Acida

a Family 1, selective reductions; family 2, dehydration to anhydrides;family 3, direct polymerizations.


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4. Top 12 Building Blocks

The following list includes top twelve building blocksidentified by the NREL and PNNL study.28

1,4-succinic, -fumaric, and -malic acids 2,5-furan dicarboxylic acid 3-hydroxy propionic acid aspartic acid glucaric acid glutamic acid itaconic acid levulinic acid 3-hydroxybutyrolactone glycerol

sorbitol xylitol/arabinitolThe NREL and PNNL study analyzed the synthesis for each

of the top building blocks and their derivatives as a two-partpathway, where the first part is the transformation of the sugarsinto the building blocks and the second part is the conversionof the building blocks to secondary chemicals or families ofderivatives. Biological transformations account for the majorityof the routes from plant feedstocks to building blocks, but

Table 9. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Glucaric

Acida

a Family 1, dehydration; family 2, direct polymerizations.

Table 10. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Glutamic

Acida

a Family 1, hydrogenation/reduction.

Table 11. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Itaconic Acida


Table 12. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Levulinic

Acida

a Family 1, reductions; family 2, oxidations; family 3, condensations.


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chemical transformations predominate in the conversion ofbuilding blocks to molecular derivatives and intermediates. Thechallenges and complexity of these pathways, as brieflyexamined by the NREL and PNNL study to highlight R&Dneeds that could help improve the economics of producing thesebuilding blocks and derivatives, have been described here foreach of the twelve building blocks (Tables 5-16).

5. Conclusion and Final Remarks

The paper has discussed the concept of biorefineries, differenttypes of biorefineries, future directions, and associated technical

challenges. The biorefinery concept is still in its infancy. It isimportant to formulate standards for the products obtained fromthe biorefineries, if not available, starting from the onset of thetechnology so that the variability of the intermediate productsis minimal to the streamline with existing technologies. Onefactor that needs critical thinking is whether modern biorefineriesshould be geared toward producing an entirely new line ofchemicals/products, such as platform chemicals that are precur-sors to high value chemicals, or to produce raw material that

Table 13. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of

3-Hydroxybutyrolactonea


Table 14. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Glycerola

a Family 1, oxidation; family 2, bond breaking (hydrogenolysis); family3, direct polymerization

Table 15. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of Sorbitola

a Family 1, dehydration; family 2, bond cleavage (hydrogenolysis); family3, direct polymerization.

Table 16. Building Blocks, Pathways, Their Transformation toDerivatives, Technical Barriers, and Potential Uses of

Xylitol/Arabinitola

a Family 1, oxidation; family 2, bond cleavage (hydrogenolysis); family3, direct polymerization.


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could be starting feedstock for existing refineries or chemicalplants. The answer to this paradigm will help in long-termsustainability of the integrated biorefineries and also help incontinual use of the infrastructure network that is already in

place which took decades if not centuries to develop to whereit is today.

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Fernando S - 2006 - Biorefineries-current Status, Challenges and Future Direction

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Transcript of Fernando S - 2006 - Biorefineries-current Status, Challenges and Future Direction