point of view: chemicals & polymers from biomass

© GEN PUBLISHING INC. , A MARY ANN LIEBERT INC. COMPANY • VOL. 4 NO. 1 • SPRING 2008 INDUSTRIAL BIOTECHNOLOGY 59

P O I N T O F V I E W

Robert Davenport

etroleum refining and petrochemical manufacturing wererapidly growing enterprises during the second half of the20th century. But before the growth of the petrochemicalindustry, organic compounds typically came from coal tar

(essentially a by-product of the steel industry) or biological sources.The biological sources themselves may have been by-products ofsome other endeavor, or the product may have been produced pur-posefully and expressly to obtain the desired molecules (even if whatthose molecules were was not precisely known at that time, morethan a century ago).

The origins of the chemical industry are complex; it finds its rootsin the need for many materials used by many industries. But thepetrochemical industry, which has brought us cheap polymers thathave virtually endless uses, grew in parallel with petroleum refining.And of course, the growth of petroleum refining was spurred by theever greater need for energy, especially to propel individual con-sumers (first, in their family, and then, in their personal, automo-biles). Thus petrochemicals and transportation fuels have been close-ly linked for over half a century.

Various secular events are poised to change that relationship.Several factors are changing the status quo of energy and its sources.These include, but are not limited to, the following:

• A presumed, and certainly feared, near-term peaking of petrole-um extraction

• Increasing demand for energy by large, developing economiessuch as China and India

• Concerns about the effect of greenhouse gases, especially carbondioxide, on the global climate

• A desire for domestic energy independence by many govern-ments worldwide

One of the major outgrowths of these trends is the phenomenalinterest in the use of biomass to produce transportation fuels. The

construction of bioethanol plants in the Western Hemisphere and thepervasive construction of biodiesel plants internationally representan unprecedented amount of capacity building. In one sense of theword, these plants are chemical plants, i.e., with biomass and processchemicals “in,” and fuel and by-product molecules “out.”

As economies around the world scramble to supply as much ener-gy demand as they can from biomass sources, there is bound to bean effect on the traditional relationship of petroleum-based fuels andpetrochemicals. But several things must be noted. As the supply ofpetroleum-based energy begins to wane, many alternatives will bedeveloped to fill the demand. This will include solar, wind, coal liq-uefaction, geothermal, and (much to the dismay of some) nuclear.None of these alone will replace petroleum, especially for motorfuels. Indeed, the portion that will be filled by biomass by the middleof this century is not likely to be much more than 4–5% of totalenergy demand (although much of this will be for liquid motor fuelsand, importantly, will thus fulfill a higher portion of demand for liq-uid transportation fuels than for total energy).

Nonetheless, the projected amount of biofuel production still repre-sents a lot of biomass-derived fuel, which is bound to have an impacton chemical use and production. Also, as the petroleum refining indus-try begins to shift in importance, the way in which organic chemicalswill be derived will also need to change. Just as petrochemicals, ororganic chemicals, have been derived in conjunction with petroleumrefining, chemicals will increasingly become derived from biomass.Despite perceptions, Figure 1 shows that this development will besomewhat more of a return to the past than an entirely new event.

Just as biomass will for some time represent only a small portionof overall energy supply, it is also likely that biomass will representonly a small portion of chemical supply. Table 1 lists in rough termsthe volume of organic chemicals and polymers produced from petro-leum and from biomass. Table 1 shows only the major organic chem-icals and polymers (essentially commodities) that are produced. Othermaterials, e.g., sulfur, are produced from petroleum and natural gas,and some inorganics can also be produced from biomass (silica, for

Chemicals & polymers frombiomass

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instance, although this represents minor production).What are the options for producing chemicals from biomass? As

mentioned, products can be purposefully produced or obtained asby-products, and sometimes as otherwise troublesome by-products.This can be the case with biomass-derived chemicals. Table 2 listsexamples of how biomass can end up as chemicals or polymers.

So what does the future of chemicals from biomass look like? Aslong as petroleum can be purchased and processed at a price com-petitive with resulting biomass chemicals, it is unlikely that petrole-um products will be significantly substituted. But with the increasingcost of petroleum and more biofuels production, it is likely that bio-logical sources will become increasingly attractive.

There are many options for obtaining chemicals from biomass,some of which have been around for centuries. Others have been the-orized or performed in pilot plants for decades but have seen limited,if any, commercialization. Yet others are now viable, and others stillin various stages of theorizing, piloting, planning, financing, and, insome cases, construction.

Table 3 lists a selection of some of the chemicals and polymers thatare or may be produced from biomass. Discerning which ones willactually be produced is still an exercise in forecasting with uncertain-ty. There are many factors that will ultimately influence the volumesproduced, but some of the more important factors are listed below.

• The price of petroleum. Virtually every petrochemical and biomassprocess is affected by the price of petroleum and, moreover, energy ingeneral. The net effect will vary for each product and process. Morework is needed to fully understand and rank the options.

• Progress of biotechnology. Discoveries in the realm of biotech-nology should have a large effect on what chemicals can be madefrom biomass. So-called green biotechnology will yield crops with bet-ter fatty acid profiles, more biomass per hectare, resistance to droughtand other factors. “White biotechnology” (industrial biotechnology) isstriving to produce organisms or enzymes that convert a wider rangeof substrates directly into a variety of desired chemical intermediates.

• Future of biofuels. This relationship is complex. As suggested inTables 1–3, glycerin by-product from biodiesel is poised to become a

60 INDUSTRIAL BIOTECHNOLOGY SPRING 2008

POINT OF VIEW

Figure 2. Biomass ages past and future Source: SRI Consulting

Biological-origin

primary source

• Wood• Agricultural products• Whaling• Animal by-products

• Petroleum/Tar seeps• Coal coking

?

?

Increasing use ofbiomass for

chemicals and energy

21ST CENTURY

• Improved processes(e.g. fermentation, organisms)

• Engineered crops

Declining percentage?a

Most organic chemicals frompetroleum refining andnatural gas processing

EARLY TO MID-20TH CENTURY

Similar to previous erabut smaller component

of total

Petroleum refining,natural gas, and natural gas liquids

“OLD BIOMASS” ERA FOSSIL ERA “NEW BIOMASS/BIOTECH” ERA100%

0%

Perc

enta

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for

gani

c ch

emic

als

from

fos

sil s

ourc

esTy

pica

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es

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ASS

a The question remains: With more energy being obtained from renewable (e.g., wind, solar) and resurgent (e.g., nuclear) sources, will this free up high-quality fossil sources for chemicals?


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major “petrochemical” intermediate. Should biofuels take a dramaticturn from the course currently forecast, this resource may not bethere. Such a result would have a considerable effect on the willing-ness of the chemical industry to invest in biomass-derived chemicals.On the other hand, increased production of biofuels is likely to pro-mote the development of biorefineries that produce a range of fueland chemical products.

Chemicals from forestryThis has long been one of the major biomass sources. The first

gathering of exudates from trees for chemical purposes is lost to his-

tory. Systematic use of this resource, especially from conifers, wasbolstered by demand for shipbuilding materials; hence such productsas rosin and turpentine have historically been called “naval stores.”Their availability increased when modern pulp and paper operationscreated such products in relative abundance.

Nevertheless, only a portion of these resources is recovered aschemicals. Depending on the pulping processes, it is much more eco-nomical to burn these hydrocarbons as part of the pulping chemicalrecovery process and to obtain energy values from them directly.

A number of alternative pulping processes have been proposed thatwould place a higher priority on recovering chemicals. Figure 2 com-pares two materials flows: one for a focus on pulp and paper, and onewith more emphasis on maximizing chemical production from forestry.

Cellulose is a major source of fiber, and this extends beyond theobvious purely natural product, cotton. Rayon is a familiar fiber, andit is nothing more than regenerated cellulose, as are cellophane andsome similar products. Synthetic cellulosic material (synthetic in thatthe natural glucose monomers have been rearranged or chemicallymodified) will remain an important business.

Biofuels by-productsThis is a key area for biomass-derived chemicals. Ever increasing

supplies of biodiesel are yielding likewise increasing supplies of theby-product glycerin. This has been sufficiently dramatic that glycerin

BIOBASED CHEMICALS & POLYMERS

Table 1. Global organic chemicals: The big picturePRODUCTION, 2006

(MILLIONS OF METRIC TONS)Basic petrochemicalsa 343

Use in polymers 243 (71%)

Chemicals from biomass 18

Polymers from biomassb 5

Total biomass 23a Includes methanol, ethylene, propylene, butadiene, butylenes, benzenes, toluene, and xylenesb Includes plastics, elastomers, fibers, and surface coatings. For biomass products, only bio-

mass-derived portion included. Biomass also does not include such products as cotton,wool, and natural rubber (which would increase amount manifold)

SOURCE: SRI Consult ing

Table 2. Global chemicals and polymers from biomass (2006)MILLIONS OF METRIC TONS

ChemicalsNatural products 0.5

Forest by-products 3.4

Food/agriculture 4.5

Biofuel by-products 1.2

Fermentationa 8.1

Decomposition products 0.2

Total 17.9Polymers

Forest products and by-products 4.3

Fermentation small

Food/agriculture 0.2

Natural products 0.1

Total 4.7a Does not include ethanol for fuel purposes


SOURCE CURRENT POTENTIALForestry Rosin, turpentine Lignin derivatives

Cellulosics Cellulosic ethanol

Natural products Flavors, fragrances New derivativesWaxes

Food and agriculture Fatty acids, alcohols

Biofuel by-broducts Glycerin Numerous glycerin derivatives such asepichlorohydrin, propyleneglycol, many others

Fermentation Ethanol Ethylene derivatives such Polylactic acid as polyethylene

Additional new polymersSuccinic acid and derivativesMany other products

Decomposition Furfural Wide range of hydrocarbonsproducts via synthesis gas from bio-

mass processing


Table 3. Selected chemicals and polymers that are/could beproduced from biomass


is now used to manufacture the very intermediate that was once usedto manufacture glycerin, namely epichlorohydrin.

But a wider variety of biofuels is being sought to supplementethanol and biodiesel. One of these is butanol. Should this become awidely produced alcohol, butanol would also open up the arena formore use of biofuel components themselves as chemical intermediates.

Ethanol was once examined as Brazil’s route into chemicals fromdomestically produced and sustainable resources. While Brazil’s useof ethanol as a motor fuel has been greater than elsewhere (in termsof market pervasiveness), the use of ethanol for chemicals has notdeveloped in kind, as it has simply proven uneconomical to date.This may now change. At least a few companies are planning to pro-

duce ethylene from ethanol (through dehydration) and to producepolyethylene from ethanol, in turn.

FermentationFermentation is the preferred production route for a number of

compounds, many intended for the food and beverage industries. Butincreasingly, this millennia-old technology is being examined tomanufacture a number of bulk and fine chemicals. (Ethanol is, ofcourse, produced by fermentation, but current main industrial inter-est is in ethanol as a biofuel.)

Biotechnology imagination is perhaps the only limit to what mightbe produced through fermentation. Several chemical intermediates are

62 INDUSTRIAL BIOTECHNOLOGY SPRING 2008

POINT OF VIEW

Figure 2. Pulping process alternatives; material flows for chemicals from forestry

Chips PulpChemicalpulpingaHarvest

Waste Energy Waste

Pulp and paper emphasis

Harvest Chips Pulp Paper

Waste Waste

Biorefinery concept

Paper

Chemicalby-productsb

Pulpingchemicalrecycle

Chemicalrecoveryupgrade

Chemicalpulpinga

Prepulpingprocessingc

Chemicalsfrom solventextraction

Ligninhemicellulose

Furtherchemical

processingChemicals

Pulpingchemicalrecycle

EnergyWasteresidue


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generating a lot of interest. One confounding factor in identifyingpotentially favored intermediates is the fact that so many can bemanufactured from each other. Once the most economical routes frombiomass to the ultimate end-use products have been determined, thensome clarity about these preferred intermediates may materialize.

Lactic acid is a relatively new monomer for the production ofpolymers. Use of this product is still limited in terms of entire marketpenetration, but several factors should increase its use, includingbiodegradability and the sustainability of its source.

Partial decomposition routesThis category includes a number of decomposition and partial

decomposition routes. The most notable of these is Fischer-Tropsch.In this familiar process, synthesis gas is generated that can be used toproduce, theoretically, almost any simple hydrocarbon. All one needsis energy and a source of hydrogen, carbon, and oxygen. Biomassfills this need well, but where Fischer-Tropsch has been used, coalhas been the main starting material to date.

Could biomass be the source of these elements and energy?Theoretically, yes, but the cost remains an issue and will likely be sofor some time.

Of course partial decomposition of complex molecules such aslignin and cellulose are also possibilities for production of chemicalintermediates. Furfural is one example of an organic intermediatemade by partial decomposition of biomass (typically oat hulls)through chemical processes. Again, it is cost that will determine thedegree of adoption of partial decomposition as a production route.

Natural productsPerhaps the oldest method of obtaining chemicals from biomass,

natural-product production, is limited in the volumes of materials thatcan be made. This method currently consists of extracting relativelyhigh-value, complex chemicals obtained from plant matter. For indus-trial purposes, this may be the cheapest way to produce these products.Some uses for these materials require natural sources; certainly thesenaturally derived products have some cache, at least for marketingpurposes, if not otherwise. These materials may perform their functionswith less impact on the environment, as they are often biodegradableor possess some similar environmentally attractive attribute.

Agriculture/food; processingSome crops are grown for nonfood uses. Of the fats and oils not

used for foods and cosmetics or that are converted to biodiesel, chem-

icals are still a major end use—including the production of a large por-tion of the fatty acids and alcohols employed in chemical applications.

Glucose can be hydrogenated to produce sorbitol. While much ofindustrially produced glucose is used in food products, this is also achemical intermediate.

SummaryThere should be an increasing prevalence of chemicals produced

from biomass during the coming years. Ironically, the sources ofchemicals from biomass that have been used for quite some timemay not be the sources that provide much of this extra growth, withone exception, namely, fermentation to ethanol.

Naval stores, natural products, and some agriculturally derivedchemicals probably have limitations on their growth, set by thegrowth of current products and markets. But new fermentationprocesses, biorefineries, new thermal processes, and biofuel by-prod-ucts (including some biofuel molecules as intermediates) all showsome promise as major new sources of chemical intermediates. Allthis, of course, will boil down to competitive economics. Indeed, if theeconomics for biofuels continues to improve, then ethanol, once pro-duced in large quantities by hydrating ethylene, may itself become aviable source of ethylene. Such developments could greatly spur anew era of chemicals and materials production from biomass.

Certainly of concern is the issue of the sources of biomass and thepotential competition of land for biomass (for chemicals or energy)with land for food. Since chemicals only use about 5% of petroleum,it seems likely that land for energy-biomass will be the main compe-tition for land. Contrary to some popular opinion, some analystshave determined that production of biomass for fuels (and chemicals)can also have a positive impact on food production. For example, ifone considers soy meal as a primary soy food product and soy oil asa by-product, then increased use of soy oil for fuels or chemicalsmay not necessarily have a negative impact on food production.

Then there is the holy grail of cellulose used as a feedstock. Whenprocesses are implemented that allow the entire plant (virtually anyplant) to be chemically converted—economically—to chemicals orenergy, the biobased economy will truly have arrived.

Robert Davenport is director for SRI Consulting’s Safe & Sustainable ChemicalSeries, Phone: (650) 384 4350. E-mail: [email protected]. Web:www.sriconsulting.com.

BIOBASED CHEMICALS & POLYMERS


point of view: chemicals & polymers from biomass

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