Contributed by Lauren Winstel, ACS Green Chemistry Institute® Research Assistant

 

The Green Chemistry Challenge awards, administered by the EPA in partnership with the American Chemical Society (ACS) and its ACS Green Chemistry Institute® , recognize and promote innovations in chemical technology that reduce waste and the use and generation of hazardous chemicals. Past winners have gone on to commercialize their technology, grow their company, and improve upon their process with the increased recognition that the award provides, often leading to third party funding or buyout offers.  The following is a summary and the future outlook of the most recent award winners, who were honored and recognized at the 21st Green Chemistry and Engineering Conference in Reston, Virginia last week.

 

1. Academic Category – Eric J. Schelter, Ph.D., University of Pennsylvania

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The 2017 award in the Academic category features targeted coordination chemistry towards separations and recycling of rare earth metals, using tailored metal complexes and ligand synthesis.  Rare earth metals are essential components in many modern technologies, from personal electronics and lighting to renewable energy. However, these applications require various mixtures of elements which are difficult to separate once combined. In order for rare earth metals to be reused, the pure elements need to be isolated and extracted from consumer products in various recycling streams, which is one of the biggest challenges related to critical elements. Electronic waste is currently an elemental sink, to the point that the amount of rare earth metals found in e-waste is greater than known quantity within global reserves of such metals.

 

In order to solve this problem, Professor Schelter and his research group have come up with a simple and cheap method of extraction using a ligand framework that takes advantage of solubility differences.  Through combining metal mixtures with a benzene or toluene solvent, solid-liquid equilibrium can be identified which allows for quick separation.  Using the example of Neodymium (Nd) and Dysprosium (Dy), which are often used in large magnets, Schelter’s experiments showed that when starting with a 50/50 mixture of the two elements, a single pass from the ligand framework created 98% pure separation, which is the minimum purity necessary for reuse.

 

When analyzing the greenness of this process, the use of benzene raises a few concerns. Schelter and his group are well aware and plan to address this unsustainable solvent in future iterations of the technology.  In the future, Schelter and his group plan to make modifications to the ligand framework, working towards using kinetic control to achieve purification, as well as focus on recycling chemistry and eventually attaching the ligand to a resin.

 

2. Small Business Category – UniEnergy Technologies, LLC

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The 2017 award in the Small Business Category features an advanced vanadium redox flow battery for grid energy storage applications produced by UniEnergy Technologies.  The need for energy storage goes hand in hand with renewable energy technology – many arguments against solar and wind power focus on their inconsistency and lack of reliability over 24 hour days.  Unfortunately, times of maximum generation for such renewable technologies often do not correspond with maximum usage in the early mornings and late afternoons.  Without storage options, the produced power goes to waste.  However, if the abundance of energy produced during daylight hours or times of continuous wind patterns could be stored and used when needed, renewables would become more reliable and readily available than nearly any other energy source.

 

This new battery, called the UniSystemTM, achieves what many energy storage attempts have failed to do before.  The vanadium electrolyte technology represents a breakthrough chemistry technique due to the increased energy density and broader operating temperature, allowing for megawatt scale storage that can be deployed in nearly any location on Earth, while also using much fewer chemicals with increased stability. Active heat management and self-contained cooling allow the battery to regulate itself, while also holding the power and energy in separate tanks, allowing for flexible and tunable usage that is not possible with conventional batteries.  This battery also has a longer lifetime than those currently on the market, and all materials are fully recyclable and non-toxic at end of life since the vanadium electrolyte is water based, immutable and does not degrade.

 

3. Greener Synthetic Pathways Category – Merck & Co.

 

The 2017 award in the Greener Synthetic Pathways category features an improved formula for Letermovir, an antiviral therapeutic agent for treatment of human cytomegalovirus.  This pharmaceutical route is greener than the original method in many ways.  The original route featured only 10% yield, estimated CO2 emissions of 1,657 kg, as well as 9 different solvents throughout the process and late stage chiral resolution which can have unpredictable results. The new process features a more reliable late stage asymmetric aza-Michael transformation using a fully recyclable and chemically stable organocatalyst.  The greener route also achieves high conversion and purity, increasing overall yield by over 60% at a low cost, all while using a through process with only 2 solvents and recycled reagents.

 

The final catalyst in this process is toluene, which is not ideal.  However, a lot of effort was put towards optimizing this drug for sustainability and atom economy with positive results; the new process reduced the carbon footprint of Letermovir by 89% and water usage by 90%.  With future improvements, Merck believes that this process is only a few steps away from zero-waste manufacturing.

 

4. Greener Reaction Conditions Category – Amgen Inc. and Bachem

 

The 2017 award in the Greener Reaction Conditions category features an improved technology for solid phase peptide synthesis, created as part of a collaboration between Amgen and Bachem. The pharmaceutical industry is often very energy intensive with high consumption of water, as well as inefficiently using many different materials and solvents in high quantities while yielding very small amounts of product. Peptide-based pharmaceuticals are an important part of therapeutics, including ParasabivTM and its active ingredient Etelcalcetide which is used to treat hyperparathyroidism. The newly designed manufacturing process has improved upon many of the unsustainable factors: shortened development processes equating to a 56% decrease in manufacturing time; high coupling yields resulting in a 5-fold increase in manufacturing capacity; the elimination of 1,440 cubic meters of waste, including 750 cubic meters of aqueous waste; and a 51% decrease in solvent use creating much cleaner reactions.

 

The future of this process lies in continued solvent reevaluation – according to green chemistry principles as well as Amgen executives, “the best solvent is no solvent at all.” Due to its broad applicability, this synthesis process has the potential to be used for manufacturing of many other peptide-based pharmaceutical products in the future.

 

5. Designing Greener Chemicals Category – Dow Chemical Co. and Papierfabrik August Koehler SE

 

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The 2017 award in the Designing Greener Chemicals category features a breakthrough sustainable imaging technology for thermal paper that uses air-voided structures.  Thermal paper is very prevalent in everyday life, widely used for point of sale receipts, tickets, tags, and labels, all of which are often quickly discarded after use. The new manufacturing method takes a process that was previously chemically intensive and environmentally toxic due to lack of recyclability, and turns that process into a physical change reaction that occurs completely void of chemical interaction.

 

The new paper consists of three simple layers.  The top layer is comprised of voided opaque polymers, with a colored layer underneath, followed by a base layer.  When heat is applied to the opaque layer, the air void particles instantly collapse to reveal the color below. This process eliminates the need for ink, avoids manufacturer and consumer exposure to imaging chemicals, as well as improves long term storage capabilities since the contrast created will not fade even under direct and severe sun exposure.  The final product is compatible with existing thermal printers and is also directly recyclable with normal paper recycling steams, which creates a new recycled feedstock potential that was previously sent into landfills.

 

 

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Contributed by Lauren Winstel, ACS Green Chemistry Institute® Research Assistant

 

Photosynthesis is one of the most fundamental processes in nature, absorbing ever-present sunlight, water and carbon dioxide, and then converting it to glucose and oxygen. When combined with modern technology, this basic process can be applied to many different industries. The result is a “bionic leaf” that can mimic energy conversions, creating various commercially viable fuels as well as chemical feedstocks. Conventionally, hydrogen is produced through the oxidation of methane, or the steam reforming of fossil fuel waste gases. This technology has the potential to sustainably produce hydrogen gas using simple inputs from the air using catalysts that are non-toxic and made from abundant elements. Over the last few years, two research teams have been developing different versions of the “bionic leaf” technology, both with their own advantages that have the potential to go above and beyond the initial goal of hydrogen gas production.

 

The basic concept of artificial photosynthesis is focused on water splitting, where H2O molecules are broken down into their separate oxygen and hydrogen atoms. Hydrogen production in this manner has been studied by many different research groups over the years, including one of the very first artificial leaves developed by Nocera Lab that used indium/fluorine tin oxide membranes combined with phosphate and cobalt catalysts. Daniel Nocera was one of the first scientists to devote his studies to artificial photosynthesis, and he is often unofficially credited with the creation of the first “practical bionic leaf” in 2008. A major development in the technology was made in 2014, when Nate Lewis and his research team at the California Institute of Technology (CalTech) greatly increased its sustainability, efficiency and safety over all previous attempts at the time because its reaction was chemically stable, and it used earth-abundant materials instead of rare elements.

 

On top of a silicon semi-conductor base, a thin coating of nickel-based oxide created a membrane that isolated the hydrogen and oxygen from each other. Separation is essential with highly reactive mixtures such as this because they are explosive when exposed to heat or electricity. When in close proximity to the current created by the leaf’s photoelectrodes, the mixture could be very dangerous. However, the transparent film produced at CalTech eliminates this possibility by holding the split molecules completely separate. The result is an infinite supply of usable hydrogen and oxygen created by a system solely powered by sunlight.

 

The most recent version of the “bionic leaf” has been developed by Daniel Nocera and his group of researchers at Harvard University. Nocera has continuously improved his technology over the years, and the newest version builds on the concepts from Nocera’s own product from 2011 as well as Lewis’ technology. The 2017 edition swaps the nickel-molybdenum-zinc catalyst for a cobalt-phosphorus alloy. The purpose for this change was to make the separation membrane more bacteria-friendly, since the previous nickel-based catalyst coating was poisonous to microbes. This allowed Nocera to pair the water-splitting technology with Ralstonia Eutropha bacteria, which takes the entire process one step further. Nocera’s version not only isolates hydrogen for potential fuel use, but it also creates a bioplastic fertilizer that improves crop growth.

 

Nocera’s team has engineered a microbial organism that works in tandem with their “bionic leaf.” The microbe’s sole food source is hydrogen, and it also contains nitrogenase, an enzyme that absorbs nitrogen from the atmosphere. This microbe intakes carbon dioxide combined with the hydrogen produced by the “bionic leaf,” and then it has the potential to produce two different products. One option is that the organism could create a hydrogen-based fuel that it expels. The second option is the creation of polyhydroxybutyrate, a bioplastic that would be stored inside the organism as a fuel source for basic cellular activity. This second option was implemented and put into a feedback loop, and as a result, Nocera and his team created a self-sustaining organism.

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In addition, this organism also uses the hydrogen from the “bionic leaf” in a third way.  Due to the nitrogenase within the microbe, it can absorb nitrogen and then combine it with hydrogen to create ammonia. Because of a molecule block inserted into the microbe, none of the ammonia is absorbed into the cells. Instead, the ammonia builds up until it begins to be expelled from the organism at a constant rate. At this point, the microbe can be buried and produce an infinite amount of ammonia-rich soil. The improvements in crop yields can be clearly seen in Figure 1. Not only does this fertilizer increase the size of crops, but it also isolates the ammonia under the ground in the soil instead of being topically applied like many conventional fertilizers. This could greatly reduce agricultural runoff when it rains, which would reduce algal blooms that are often found in waterways downstream of croplands.

 

While Nocera’s and Lewis’ basic technologies are very similar, the final applications are very different. The minor change in membrane material allowing for microbial growth created an entirely new avenue of applications in agriculture. Bionic leaves and artificial photosynthesis play an important role in the future of the green revolution. What began as mimicking nature has become a method of improving upon it and creating artificial processes that surpass their natural counterparts in both efficiency and sustainability.

 

 

“The Nexus Blog” is a sister publication of “The Nexus” newsletter. To sign up for the newsletter, please email gci@acs.org, or if you have an ACS ID, login to your email preferences and select “The Nexus” to subscribe.

 

To read other posts, go to Green Chemistry: The Nexus Blog home.

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American Chemical Society Expresses Concern over Executive Order on Climate Change

March 29, 2017 | American Chemical Society

The ACS public policy statement on Global Climate Change specifically supports the importance of addressing Earth’s changing climate and calls for international cooperation to address the issue.

 

AkzoNobel has Developed Intelligent Biocides for Coatings in the Shipping Industry

March 28, 2017 | The Guardian

Scientists at AkzoNobel, a global paints and coatings company, are using principles derived from nature to develop coatings that protect surfaces such as the hulls of cargo ships, which could save fuel and emissions.

 

General Mills is Making Efforts to Improve the Agricultural Supply Chain

March 27, 2017 | GreenBiz

To reduce its footprint, General Mills has set a goal of cutting greenhouse gas emissions by 28 percent by 2025. It’s moving towards zero waste-to-landfill at 100 percent of its production facilities over the same time frame. And it has committed to sustainably sourcing 100 percent of 10 key ingredients.

 

Amgen Executive Shares How Green Chemistry has Become Vital to the Pharmaceutical Industry

March 27, 2017 | C&EN

Margaret Faul, leader of the sustainability transition, discusses the firm’s strategy to reduce waste and save time and money

 

How Green Chemistry is the Key to Reduced Waste and Improved Sustainability

March 26, 2017 | The Conversation

Making chemical compounds, particularly organic molecules (composed predominantly of carbon and hydrogen atoms), is the basis of vast multinational industries from perfumes to plastics, farming to fabric, and dyes to drugs.

 

New Hydrogen Production Catalyst Developed at Aalto University

March 24, 2017 | The Chemical Engineer

Engineers at Aalto University, Finland, have developed an electrocatalyst for hydrogen production which uses 100 times less platinum than conventional electrocatalysts, yet with similar efficiency, which could be used as a low cost option for renewable energy storage.

 

 

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To read other posts, go to Green Chemistry: The Nexus Blog home.

In 2004, the United States Department of Energy published a landmark report titled “Top Value Added Chemicals from Biomass,” in which they highlighted a dozen molecules as the most promising framework molecules that could potentially replace commonly used petroleum-based molecular building blocks. These 12 biobased value-added chemicals would provide prospective routes for everything from biofuels to less toxic paints and adhesives, which can be seen in Figure 1.  Despite the fact that these innovations took almost 13 years to garner attention and be developed on an industrial scale, these molecules now embody the promising future of the biobased economy.  The following update features four biobased chemicals with recent innovations on the market:  Itaconic Acid, Glucaric Acid, 3-Hydroxybutryolactone, and 5-Hydroxymethylfurfural.

 

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The basic chemical composition of itaconic acid is similar to the petrochemicals currently derived from maleic acid/anhydride.  Maleic anhydride is the basis for many coatings and polymers and is currently produced in large volumes for this purpose.  Itaconic acid’s functionality lies in two distinct carboxylic acid groups that allow the molecule to be easily broken down into monomers and rearranged into various chemical structures.  However, this production and reconstruction process is often slow and comes at a high economic cost, contributing to a slow uptake from manufacturers over the past decade.

 

In 2004, the key barrier to commercial success for this biobased chemical was its limited polymerization potential.  However, one company has devoted itself to building up the itaconic acid market for the past 20 years, creating biobased polymers for various small-scale industrial and commercial applications. A recent agreement with AkzoNobel expands Itaconix’s economic resources and will likely accelerate the rate at which itaconic-based polymers are commercialized.

 

Holding 42 current patents, Itaconix sells a multitude of products in the homecare, industrial, and personal care markets. These include: non-phosphate water conditioners for dish detergents, agriculture, and industry; a no-residue odor neutralizer; mineral dispersion polymers; low-VOC paint and coating binders; flexible formaldehyde-free encapsulation technology; and even a bio-based hair styling polymer. The variety of compositions and applications of Itaconix’s products have enormous potential once they achieve commercial-scale production and market equality with conventional petroleum products.

 

Glucaric Acid (also called Saccharic acid)glucaric.png

 

This organic sugar comes from inexpensively obtained glucose oxidized with nitric acid, which serves as a conversion catalyst for complex sugar polysaccharide breakdown. The resulting simple sugar monosaccharaides can then be used further in biorefineries. One high value application for glucaric acid is as an intermediate in the production of biobased adipic acid, which is used to produce various polyurethanes, non-phthalate plasticizers and biodegradable polyesters, as well as 100 percent renewable nylon-6,6 fibers. This nylon is widely used in the textile and plastics engineering industries.  Glucaric acid is a key feedstock that could make the process more sustainable and is currently being developed by Rennovia Inc.

 

Another company investing in glucaric acid technology is Rivertop Renewables, whose commercial production facility manufactured more than nine million dry pounds of sodium glucarate in 2016.  Their patented chemical oxidation process fully converts the glucose feedstock by utilizing every carbon atom and adding oxygen weight, allowing for greater acid production compared to C6 sugar feedstock input. The process also allows for reagent recovery, leading to low energy consumption throughout the manufacturing process.

 

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As a cyclic C4 sugar compound, 3-HBL requires multiple chemical transformations during production and, therefore, is not considered to be an economically viable option as a chemical building block.  However, various high value derivatives, such as gamma-butenyl-lactone and acrylate-lactone, can result from dehydration and esterification respectively. Such derivatives have potential applications in the formation of new polymers. Considering that 3-HBL is labeled a specialty chemical with fairly high value uses, not much research has been done on commercialization or potential as a commodity chemical intermediate. However, a small startup called Kalion Inc. is challenging convention by producing 3-HBL in high volumes for pharmaceutical applications.

 

Kalion is providing a low cost and highly efficient production route to 3-HBL, which they intend to commercialize. The main advantage of Kalion’s process is the ability to specify the chirality of the molecule and then use 3-HBL as a pharmaceutical intermediate. The basic core structure, along with the chiral specificity of 3-HBL, may potentially benefit the emerging Oxazolidinone class of antibiotics, with higher purity rates and lower costs than traditional antibiotic production methods.

 

5-Hydroxymethylfurfural  (5-HMF)5hmf.png

 

Although not among the “Top 12” highlighted in the DOE report, this molecule was identified in the study as a major biobased chemical building block derived from starch and cellulosic C6 sugar feedstocks. 5-HMF can be synthesized from different types of C6 carbohydrates through dehydration.  According to Ava Biochem, the special characteristics of 5-HMF make it “a key chemical in biochemistry and an important ingredient in the industrial production of polymers,” including resins and additives.  Avalon Industries, the current market leader in 5-HMF production technology and applications, uses a cost-efficient and scalable method of hydrothermal processing to produce 5-HMF. Avalon is currently developing 5-HMF based adhesives of various types, such as phenolic, melamine and urea resins.  Avalon’s goal is to create a 100 percent biobased and sustainable non-toxic adhesive in which 5-HMF fully replaces formaldehyde in each of the resin formulations.

 

5-Hydroxymethylfurfural contains an aldehyde group, as well as an alcohol functional group, which allows for various structural reformations once broken down into furan-monomers and corresponding polymers, leading to more than 175 product derivations and 20 different high-performance polymers. These furan derivatives have been called the “sleeping giants” of renewable chemicals due to their enormous market potential. As a key intermediate between biomass and biochemicals, 5-HMF is primarily seen as a natural, toxin-free formaldehyde replacement, which is also often biodegradable in product form. One key application lies in oxidation with furandicarboxylic acid (FDCA) as a basis for polyethylene furanoate (PEF) manufacturing, currently in commercial-scale production at several companies, including BASF, Avantium and Eastman. PEF made from 5-HMF is a biobased substitute for polyethylene (PET), which is widely, and wastefully, used in soft drink bottles and food packaging. Further applications for 5-HMF currently being developed by Avalon include agrochemicals, pharmaceutical active ingredients, wood composites, paints, and coatings.

 

 

These advancements collectively represent the general furthering of the biobased and renewable chemicals economy over the past decade, and reinforce the promise of a biobased future. According to McKinsey & Company, estimated “worldwide production of biobased products is projected to grow from approximately $203.3 billion in 2015 to $400 billion by 2020 and $487 billion by 2024.”  Sustainability initiatives, as well as non-toxic alternatives, are gaining priority in the chemical industry, and one can expect an increased number of promising developments from these molecules in the future.  Biobased formulations have the potential to replace a majority of petroleum-based chemical feedstocks and derivatives, therefore making everyday products greener on the most basic molecular level.

 

 

“The Nexus Blog” is a sister publication of “The Nexus” newsletter. To sign up for the newsletter, please email gci@acs.org, or if you have an ACS ID, login to your email preferences and select “The Nexus” to subscribe.

 

To read other posts, go to Green Chemistry: The Nexus Blog home.

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