Trends in biobased chemistry.
The commercial landscape for biobased chemicals and materials is dynamic and ripe with opportunities. There are many drivers for this activity, including the increased value of chemicals relative to fuels, (1) the relative costs of petroleum and biobased feedstocks, the political risks associated with US dependence on foreign oil, climate change, and a growing consumer demand for biobased products. However, the domestic petrochemical outlook has changed markedly in the past few years due to fracking and horizontal drilling technologies which have given rise to inexpensive natural gas as well as crude oil from "tight oil" formations. (2) Prior to 2012, growth in domestic chemical production had stagnated. (3) This dramatic change in the cost of US fossil feedstocks has initiated a rebound in domestic petrochemical production. (4) The false idea that petrochemical feedstocks are being exhausted, creating unlimited opportunities for biobased chemicals, has now clearly been debunked. Commercial strategies for biobased chemicals must be based on disciplined cost/performance metrics which are robust within this paradigm.
Historic Biobased Chemistry
Biobased chemical technology is seeing resurgence today, but it is by no means new. Prior to World War II, furfural, furan and tetrahydrofuran were obtained from cellulosic materials (corn cobs). Butanol was produced by acetone/butanol/ethanol fermentation using carbohydrate substrates. Glycerol was dehydrated to allyl alcohol and acrolein, the precursor for acrylic acid, as early as the 1880s. (5) Hydrogenolysis of carbohydrates to produce 1,2-propylene glycol ethylene glycol and glycerol, was reported in 1933. (6) Ethanol dehydration to ethylene was documented as early as 1932. (7) The reason these biobased technologies were not successfully commercialized is obvious. During the time period of these early developments, between 1920 and 1969, the price of petroleum never exceeded $3.10 per barrel, and it was in abundant supply relative to other feedstocks. (8)
Crude oil prices were fairly stable and low through the early 1970s, but in the recent past, price volatility and environmental concerns resulted in a resurgence of alternative energy and materials research efforts. In the meantime, advances in agricultural practices over the past several decades have brought the cost of agricultural feedstocks in balance with petroleum. For example, from 1980 to 2008 there was only about a 2% increase in the number of acres of corn planted in the US, but the average yield of corn increased from 91 to 154 bushels/acre during that time frame. This represents a 69% increase in the corn yield on about the same acreage. Furthermore, these productivity improvements have not come at the expense of higher farm inputs such as fertilizers, pesticides, herbicides, additional machinery, etc. The USDA, Economic Research Service has compiled data on US agricultural output, input, and productivity since 1948. A clear trend of increasing output and productivity has been demonstrated with essentially the same inputs used between 1948 and 2006. (9)
Industry leaders expect these productivity trends to continue into the foreseeable future. Monsanto predicts that by 2030, corn yields will reach an average of 300 bushels per acre, with continued advances in agronomic and breeding technologies, as well as those due to biotechnology. (10) This would represent another doubling of output from existing acreage. These increased corn yields will also give rise to additional corn stover (stalks, leaves, cobs), which can be sustainably harvested for use as feedstocks for feed, fuel, and industrial chemical initiatives.
Biobased Materials & Building Blocks
Polymers from biobased sources still only represent less than 1% of the total polymer market today, and most of that small volume is from natural rubber and conventional cellulosic polymers. Only 3% of the 1% of biobased polymers originate from the new generation of bioplastics, namely polylactic acid, soy-based urethanes, glycerol-based materials, etc. So the impact of these materials on the overall plastics market is small. However, the growth rate for biobased plastics is high, about 13% per year, (11) providing considerable opportunity for innovation.
Carbohydrates are the predominant feedstock for biobased chemicals due to their low cost and abundance. If one examines the building blocks being commercialized from carbohydrate sources, they have one thing in common; they contain carbon, hydrogen, and oxygen, the atoms from which these feedstocks are composed. Efficient atom economy translates directly into the cost of these products. Figure 1 lists many of the chemicals that can be generated from microbial fermentation using carbohydrate substrates. These include ethanol, n- and iso-butanol, poly(hydroxyalkanoates), lactic acid, 3-hydroxypropionic acid, diacids (such as succinic, fumaric, and adipic), diols (such as 1,4-butanediol and 1,3-propanediol), isoprene, farnesene, and other olefins from alcohol dehydration: ethylene, propylene, and butadiene.
Carbohydrates are also being chemically transformed to chemicals as shown in Figure 2. These chemicals include dextrose and xylose, and their hydrogenated counterparts, sorbitol and xylitol, isosorbide, glucaric acid, levulinic acid, ethylene and propylene glycol, furfural, hydroxymethylfurfural, furandicarboxylic acid, p-xylene and terephthalic acid, and glycerol derivatives including acrolein, acrylic acid, and epichlorohydrin.
Most of the chemicals shown in Figures 1 and 2 are building blocks for polymers. A few are good candidates for platform molecules and high volume commodities due to their low cost and abundant supply. Werpy and Petersen (12) and Bozell and Petersen (13) have proposed a more expansive list of these platform chemicals. They include ethanol, glycerol, butanol, dextrose, and hydroxymethylfurfural, most of which are also being considered for the biofuels market for the same reason. Ethanol is an excellent example of a material being targeted as both a biofuel and a platform chemical for reasons of cost and availability. Braskem and others, primarily in Brazil due to the low costs of sugar from cane, are producing ethylene from ethanol and converting it to polyethylene. Other ethylene derivatives in the commercial pipeline are propylene via ethylene metathesis, ethylene oxide and vinyl chloride.
Butanol also has potential as a platform chemical. Butamax and Gevo are leading producers of isobutanol, which was chosen over n-butanol because its fermentation is much superior, having higher yields on glucose as well as significantly higher titer and productivity. Isobutanol can be readily dehydrated to isobutylene, which is a polymer building block. Gevo has also patented a process by which isobutylene is dimerized to p-xylene, the petrochemical precursor to terephthalic acid. (14)
Glycerol has emerged as a key platform chemical due to its low cost and large availability as a by-product from biodiesel production, (15) It can be used to produce many core industrial monomers. In fact, there have been a number of announcements over the past five years with regard to glycerol as a feedstock for industrial chemicals. (16) Cargill/Ashland, ADM [Archer Daniels Midland], Dow, and Synergy announced their intent to produce propylene glycol from glycerol. In all cases, glycerol is converted to propylene glycol via hydrogenolysis. (17)
Both Dow and Solvay announced their intent to produce epichlorohydrin from glycerol, which in the past was the petrochemical precursor for glycerol. Solvay is commercializing glycerol-derived epichlorohydrin through Vinylthai, which is half-owned by Solvay, in Thailand. (18) This represents a true paradigm shift as a result of the low cost of biodiesel-based glycerol. It is no longer made from epichlorhydrin, but instead is being used as a feedstock for epichlorohydrin.
Huntsman has announced plans to produce glycerol carbonate from biobased glycerol, and Arkema is exploring technology to produce acrolein, a precursor to acrylic acid from glycerol. However, many of these ventures have been delayed due to the recent downturn in the economy and the limited availability of biodiesel-based glycerol. Roughly 11 million metric tons of biodiesel were produced globally in 2008 from which about 1.1 million metric tons of crude glycerol was produced. (19) The total market for refined glycerol was about 900,000 metric tons in 2005. (20) As can be seen in Figure 3, the level of glycerol available from biodiesel production is small compared to the multi-million metric ton per year target chemicals to be produced from it. The supply of glycerol is not limited to oilseed sourcing. If the demand for glycerol grows, it can also be produced from carbohydrate fermentation or by hydrogenolysis of carbohydrates. (17)
ADM is producing bio-propylene glycol from its facility in Decatur, Illinois, from the hydrogenolysis of glycerol and sugar alcohols. In addition to ADM, Global Biochem is also producing glycols via hydrogenolysis in China using sorbitol as the feedstock. (21)
Biobased propylene glycol has achieved the same product specifications as petrochemical propylene glycol. Furthermore, life-cycle assessment of biobased propylene glycol estimates greenhouse gas impacts for production of bio-based propylene glycol from soybean derived glycerol are approximately 80% that of petro-PG. (22)
Sugars, including dextrose, sucrose and pentoses like xylose are reasonable platform chemicals since they are substrates for most fermentation processes and their sugar alcohols are substrates for hydrgenolysis to glycols as discussed above. Further, they can be dehydrated to a family of furanics, as shown in Figure 4, which include furfural, hydroxymethylfurfural, furandicarboxylic acid, and, through Diels Alder chemistry with ethylene, aromatics such as p-xylene and terephthalic acid. (23)
Several other commodity building blocks are also being targeted, including isoprene, acrylic acid, and terephthalic acid. A fermentation process for isoprene has been developed by Danisco in partnership with Goodyear as well as by Amyris in partnership with Michelin and others, predominantly for tire applications. The recovery of isoprene from the fermentation broth, one of the most expensive steps of a fermentation process, is simplified by the fact that isoprene is a relatively water-insoluble gas that is evolved from the fermentation broth.
Acrylic acid and acrylate esters are large commodity chemicals used in superabsorbent and coating applications. At least three routes to acrylic acid are being investigated. Glycerol dehydration to acrolein, the precursor to acrylic acid, as mentioned previously, is the first. (24) Cargill, together with Novozymes and BASF, and OPX Biotechnologies, together with Dow Chemical, are pursuing a fermentation route to 3-hydroxypropionic acid, which readily dehydrates to acrylic acid. (25) It is also possible to dehydrate lactic acid derivatives to acrylates.
Finally, biobased routes to terephthalic acid are being investigated by several different chemistries. A consortium of companies made up of Coca Cola, Heinz, Ford, Proctor and Gamble, and Nike is encouraging this research, with the end-goal being a completely biobased PET packaging material. In particular, Coke is pursuing a "plant bottle" made up of 100% biobased plastic. Biobased ethylene glycol is already available from ethanol-derived ethylene. Gevo, as discussed earlier, has a chemical route to convert isobutylene to p-xylene, the petrochemical precursor to terephthalic acid. Avantium is marketing furandicarboxylic acid (FDCA) as a terephthalic acid replacement, and BP owns a patent to directly convert FDCA to terephthalic acid using Diels Alder chemistry with ethylene, although the yields are low. (26) Draths, which was sold to Amyris, also described an ethylene Diels Alder route with muconic acid to terephthalic acid. (27) Dimethylfuran can also be converted to p-xylene using ethylene Diels Alder chemistry. (23)
The Case for Renewable Incumbents
The road to commercialization for biobased products has been full of potholes from which some key lessons have emerged. Commercializing new materials has a very large financial risk associated with it. For example, Cargill Dow invested well over $1 billion to launch polylactic acid in 2004. (28) The business grew slowly because the market had to be developed. One clear lesson is that market development is much more complicated and unpredictable than the technical component of a new business launch. Dow divested in 2005 due to negative cash flow, but Cargill stuck it out, rebranding the company to NatureWorks which is now apparently healthy and expanding. This business is generating revenue today, but it will be a long time before the investment is recuperated.
A less encouraging story is that of poly(hydroxyalkanoate) (PHA), materials which have undergone several unsuccessful business launches. The most recent is that of Metabolix which partnered with ADM to introduce Mirel PHA materials. A 50,000 ton/year plant was built in an ADM facility in Clinton, Iowa, which began production in 2009, but in 2012 ADM terminated the joint venture due to lack of adequate sales. (29)
An example of a new biobased material with a clearly defined market application is DuPont Sorona[TM], a polyester of terephthalic acid and biobased 1,3propanediol. DuPont recognized that Sorona polyester could successfully compete in the carpet fiber business solely on a cost/performance basis and, therefore, sold its conventional polyester fiber business to focus on Sorona. The market was already established for this material and it needed only customer validation to be successful, which it readily received.
There are several cases where a portion of the market of incumbent petrochemicals has been displaced by their biobased counterparts. Glycerol is a good example. The petro-source for glycerol was from propylene through epichlorohydrin. Today the vast majority of glycerol is biobased, a by-product of biodiesel.
Another good example of a biobased incumbent chemical is propylene glycol, which ADM is producing from glycerol hydrogenolysis. ADM started this 100,000 metric ton/year plant in 2010, producing both industrial and USP grades. (30) Demand has been high for this biobased product, which competes with petro-propylene glycol on cost/performance with a slight advantage due to its biobased origin.
Other examples of biobased incumbents include ethanol, ethylene, ethylene glycol, acrylic acid, isoprene, terephthalic acid, butanediol, biosyn-gas, and glycerol carbonate. Each of these compete with incumbent petrochemicals based only on cost and quality metrics. Most have already been successfully commercialized.
The commercialization of biobased chemicals has had a checkered past. There have been some significant success stories including biobased ethanol and ethylene, 1,3-propanediol, propylene glycol, and others. There have also been a number of more difficult launches, in particular, those of the new biobased materials. The financial risks associated with introducing a new material and the length of time associated with developing the market make this approach only for those with considerable financial resources and the will to persist. Commercializing biobased routes for incumbent chemicals and materials is the pathway with less risk and a shorter commercialization time frame.
(1.) Adapted From: J. Frost, Industrial Biotechnology, 1, 23-25 (2005); New Scientist, (2007).
(2.) M.J. Cohen, Int. Energy Agency, 3, 18-19(2012).
(3.) CEH Marketing Research Report, "Petrochemical Industry Overview," July 2008.
(5.) A.R. Leeds, J. Am. Chem. Soc., 4 (5), 58-61 (1882).
(6.) W.H. Zartman, H. Adkins, J. Am. Chem. Sot., 55 (11), 4559-4563 (1933).
(7.) W.A. Lazier, J. V. Vaughen, J. Am. Chem. Sot., 54 (8), 3080-3095 (1932).
(8.) http://tonto.eia.doe.gov/dnav/pet/hist/LeafHandler.ashx? n=PET&s=F000000_3&f=A
(10.) B. Begemann, Monsanto presentation at Goldman Sachs Fourteenth Annual Agricultural Biotech Forum, February 10, 2010. http://www.monsanto.com/investors/documents/2010/02_10_10.pdf
(11.) L. Shen, J. Haufe, M. P. Patel, "Product Overview and Market Projection of Emerging Biobased Plastics," PRO-BIP, Utrecht University, The Netherlands, 2009.
(12.) Werpy, T., Petersen, G., DOE Top Value-Added Chemicals from Biomass, http://wwwl .eere.energy.gov/biomass/pdfs/35523.pdf,2004.
(13.) Bozell, J.J., Petersen, G. R., Green Chem., 12, 539-554 (2010)
(14.) Chem. Eng. News, 88(44), 11 (2010).
(15.) Peters, M. W.,Taylor, J. D.,Jenni, M., Manzer, L. E., Henton, D. E., US Patent 2011/0087000 A1.
(16.) Chem. Eng. News, 87(22), 16-17 (2009).
(17.) P. B. Smith, "Carbohydrate Hydrogenolysis," ACS Symposium Series 1105, P. B. Smith, R. A. Gross, eds., American Chemical Society, Washington, DC, Chapter 12 (2012).
(18.) Chem. Eng. News, 87(40), 20 (2009).
(19.) Biodiesel 2020, Introduction and Executive Summary, MultiClient Study, 2nd Edition, Published by Emerging Markets Online, 2008. http://www.emergingmarkets.com/PDF/Biodiesel2020Study.pdf
(20.) Impact of Biodiesel Production on the Glycerol Market, 2006, http://www.ruralsementes.com.br/produtos/Impact_of_Biodiesel_Production_on_the_Glycerol_Market.pdf.
(21.) http://www.globalbiochem na.com/Glycol_Prod ucts.html
(23.) C.L. Williams, C.-C. Chang, P. Do, N. Nikbin, S. Caratzoulas, D. G. Vlachos, R. F. Lobo, W. Fan, P. J. Dauenhauer, ACS Catal., 2, 935-939 (2012).
(24.) Chemical & Engineering News, 87(22), 16-17 (2009).
(25.) Chem. Eng. News, 90(35), 8 (2012).
(26.) W.H. Gong, World Patent Application 2009064515, 2009.
(29.) Chem. Eng. News, 90(5), 32-33 (2012).
Patrick B. Smith
Michigan Molecular Institute, Midland, Michigan, USA
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|Author:||Smith, Patrick B.|
|Date:||Jun 1, 2013|
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