Green success stories: The 2016 Presidential Green Chemistry Challenge Awards | June 20, 2016 Issue - Vol. 94 Issue 25 | Chemical & Engineering News
  • CORRECTION: This story was updated on June 17, 2016, to correct the type of enzyme that nitrapyrin inhibits (ammonium monooxygenase, not urease) and to correct a statistic about what percent of nitrogen applied to fields gets lost through nitrification.
Volume 94 Issue 25 | pp. 20-23 | Latest News
Web Date: June 13, 2016

Green success stories: The 2016 Presidential Green Chemistry Challenge Awards

Annual awards recognize chemical innovations that prevent pollution and promote sustainability
Department: Science & Technology
News Channels: Biological SCENE, Environmental SCENE, Materials SCENE, Organic SCENE
Keywords: green chemistry, catalysis, hydrosilylation, iron catalyst, earth abundant, alkylate, solid acid catalyst, zeolite, gasoline, green chemistry awards, pollution prevention, environmentally friendly

Few people could argue that using vegetable oil instead of crude oil, replacing platinum catalysts with iron, or avoiding the use of billions of liters of toxic and corrosive acids in petrochemical plants isn’t a good deal. These are the benefits of some of the environmentally and economically friendly innovations that are being recognized this week with 2016 Presidential Green Chemistry Challenge Awards.

Chemists attending the 20th annual Green Chemistry & Engineering Conference in Portland, Ore., are among the first to learn the names of this year’s winners: Albemarle, CB&I, Dow AgroSciences, Newlight Technologies, Verdezyne, and Princeton University’s Paul J. Chirik.

In addition to talks by the award winners, the three-day meeting will feature plenary and technical sessions on advances in green chemistry and engineering research, education, and policy issues on the incentives and barriers to adopting greener technologies.

“I’m happy to get to come to my hometown to celebrate something I am truly passionate about—ensuring a world that is green and sustainable for years to come,” says Allison A. Campbell, an associate laboratory director at Pacific Northwest National Laboratory. As president-elect of the American Chemical Society, Campbell is on hand to help present the awards.

The Presidential Green Chemistry Challenge Awards were established by the Environmental Protection Agency in 1995 as a competitive effort to promote chemical products and manufacturing processes that help the agency achieve federal goals set by the provisions of the Pollution Prevention Act of 1990. The program is administered by EPA’s Green Chemistry Program in the Industrial Chemistry Branch of the Office of Pollution Prevention & Toxics and is supported by partners from industry, government, academia, and other organizations, including ACS and its Green Chemistry Institute.

The work described in the award nominations must have been carried out or demonstrated in the U.S. within the preceding five years. An independent panel selected by ACS, which publishes C&EN, judges the nominations and selects the award winners.

Throughout the initial 20 years of the program, EPA has presented 104 awards to scientists and companies selected from more than 1,500 nominations. Through 2015, the winning technologies have made “billions of pounds of progress,” according to EPA statistics, including collectively saving 375,000 metric tons of hazardous chemicals and solvents and 80 billion L of water each year, and eliminating 3.5 million metric tons of carbon dioxide-equivalent emissions each year.

“For 21 years, the Presidential Green Chemistry Challenge Awards have highlighted best practices that incorporate green chemistry into chemical design, manufacture, or use, thereby reducing or eliminating hazardous substances,” Campbell explains. “This year’s awardees clearly demonstrate that science and technology innovation can not only address complex global issues, but do so in a sustainable and safe manner.”

Beyond the accolades for developing new technologies that prevent pollution and help companies with their bottom lines, the awards and the conference provide a foundation for the future, observes Julie A. Haack, coordinator of the Green Product Design Network at the University of Oregon. “As an educator, one of the challenges is teaching students how to design in the context of a chemical ecosystem,” Haack tells C&EN. “The Green Chemistry Challenge Awards help illustrate the elegance and robust multifaceted benefits that are possible when we apply green chemistry to the chemical enterprise as a system.”

The following are this year’s winners. Read on to learn more about how these inventions came about and how they’re positively impacting the environment.


Zeolite catalyst offers a better future for gasoline

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Albemarle and CB&I teamed up to develop a solid-acid zeolite catalyst to replace environmentally problematic liquid hydrofluoric and sulfuric acid catalysts used in the production of isooctane, the key component of the fuel-blending ingredient known as alkylate.
structures
 
Albemarle and CB&I teamed up to develop a solid-acid zeolite catalyst to replace environmentally problematic liquid hydrofluoric and sulfuric acid catalysts used in the production of isooctane, the key component of the fuel-blending ingredient known as alkylate.

When it comes to oil refining and petrochemical production, the words “environmentally friendly” usually don’t come to mind. Yet industrial technology firm CB&I and specialty chemical company Albemarle have teamed up to make them part of the vocabulary by inventing AlkyClean, a cleaner and safer process for producing alkylate, a key ingredient used in formulating gasoline. For their efforts, the companies shared the 2016 Greener Synthetic Pathways Award.

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Albemarle and CB&I's commercial-scale AlkyClean plant at Zibo Haiyi Fine Chemical in China’s Shandong Province began operating in August 2015.
Credit: CB&I
Image of Albemarle chemical firm.
 
Albemarle and CB&I's commercial-scale AlkyClean plant at Zibo Haiyi Fine Chemical in China’s Shandong Province began operating in August 2015.
Credit: CB&I

Alkylate is an ideal gasoline feedstock mainly made up of C8 branched alkanes that are free from olefins and aromatics, low in sulfur, and high in octane rating. Manufacturers typically make it by acid-catalyzed coupling of an olefin with isobutane at a global rate of 115 billion L per year.

But there are downsides to this tried-and-true approach. Conventional alkylate production requires the use of billions of liters of hydrofluoric acid or sulfuric acid, according to CB&I’s Arvids Judzis Jr. These liquid acid catalysts are toxic and corrosive, Judzis says, presenting health and safety challenges for local communities and for refinery workers who handle them. And once used, the spent acids must be regenerated or sent for disposal, which takes additional energy and further generates waste and pollution.

Refinery, catalyst, and petrochemical industry researchers have spent decades looking for a better option. The leading candidates are solid catalysts such as zeolites, which are porous aluminosilicate materials with acidic reactive sites. Efforts so far have failed in most cases because of poor selectivity for the preferred alkane products or rapid catalyst deactivation, Judzis explains. And there’s also no good way to regenerate the catalyst.

In developing AlkyClean, Albemarle researchers invented a platinum-containing alumina zeolite with optimized pore sizes and acidic sites that selectively makes high-octane trimethylpentanes over lower octane dimethylhexanes. As a bonus, the catalyst has a low susceptibility to fouling and produces minimal by-products. CB&I engineers designed and built a continuous-flow alkylate reactor system optimized for using the catalyst. It allows continuous regeneration of the catalyst by cycling from olefin addition (alkylation) to hydrogen addition (regeneration) without changing reactor conditions.

“Our AlkyClean technology provides customers in the gasoline alkylation market a solution to produce higher octane alkylate with less environmental impact,” says Philip K. Asherman, CB&I’s president and chief executive. “We are really inspired by the potential of this technology to power a greener and more sustainable world,” adds Silvio Ghyoot, Albemarle’s president of refinery solutions.

AlkyClean is the first solid-acid catalyst to reach commercial-scale production. The companies announced the successful start-up of a plant making about 155 million L of alkylate per year in August 2015 at Zibo Haiyi Fine Chemical in China’s Shandong province.


Earth-abundant metal catalysts turn the tide on silicones

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Chirik’s group and its colleagues at Momentive have developed iron, cobalt, and nickel catalysts (shown) to replace platinum in classic hydrosilylation reactions.
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Chirik’s group and its colleagues at Momentive have developed iron, cobalt, and nickel catalysts (shown) to replace platinum in classic hydrosilylation reactions.

Catalysis is at the heart of many chemical processes. To make it more cost-effective and sustainable, chemists have set out to replace precious-metal catalysts such as palladium, platinum, rhodium, and iridium with more abundant iron, cobalt, and nickel.

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Princeton’s Chirik has led an effort to pioneer development of first-row transition-metal catalysts that outshine traditional precious-metal catalysts in hydrosilylation reactions to make silicones.
Credit: Courtesy of Paul Chirik
Princeton’s Paul Chirik poses in his lab where students are conducting experiments.
 
Princeton’s Chirik has led an effort to pioneer development of first-row transition-metal catalysts that outshine traditional precious-metal catalysts in hydrosilylation reactions to make silicones.
Credit: Courtesy of Paul Chirik

Paul J. Chirik of Princeton University has provided a classic example of this trend by discovering a new class of hydrosilylation catalysts to make silicone compounds and polymers. These iron, cobalt, and nickel catalysts are less expensive, easier to use, and environmentally friendlier than the platinum catalysts they are replacing, Chirik says. And they often offer better performance. For his team’s work, Chirik has won the 2016 Academic Award.

Platinum-catalyzed alkene hydrosilylation is one of chemistry’s understated reactions. Although it’s a simple process in which a silicon hydride (RSi-H) is added across the double bond of an alkene (C=C), the reaction is critical for making silicones that are ingredients in many chemical products, from car tires and hair conditioner to releasable adhesive coatings on postage stamps and kitchen utensils such as spatulas.

The new catalysts operate on the principle of metal-ligand cooperativity, a concept pioneered by Chirik’s group in which first-row transition metals that typically promote one-electron radical processes can be used in place of traditional second- and third-row transition metals that operate via two-electron redox processes.

In collaboration with silicone manufacturer Momentive Performance Materials, Chirik’s group has shown that the iron, cobalt, and nickel catalysts are more stable and selective than platinum and work at room temperature with both terminal and internal alkenes instead of only terminal alkenes. The reaction mixtures also don’t require distillation to remove unwanted isomerized side products, as is sometimes a necessity with platinum.

Momentive engineers have estimated that if the Chirik catalysts were used to replace the world’s platinum hydrosilylation catalysts—which use some 5.6 metric tons of platinum each year, according to industry data—they would reduce energy use by 85 billion Btu per year, cut waste by 8.5 million kg per year, and reduce CO2 emissions by 21.7 million kg year.

“This recognition highlights the importance of collaboration between academia and industry to produce chemistry that spans the fundamental to the applied,” Chirik says. “Using earth-abundant elements in catalysis is often overlooked as a key component of sustainable chemistry. Hopefully our success will get more people thinking about how to use the elements on the periodic table more responsibly.”


Making every nitrogen count on the farm

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By encapsulating nitrapyrin in a polyurea shell (shown here), Dow AgroSciences’ researchers developed an aqueous formulation of the enzyme inhibitor that helps prevent soil microbes from breaking down fertilizer in the soil. The technology delivers nitrogen efficiently to plants and reduces water pollution and greenhouse gas emissions.
Credit: Dow AgroSciences
A diagram shows how fertilizers can break down from ammonium to nitrate and nitrous oxide, reducing amount of nitrogen for plants. Nitrapyrin, an enzyme inhibitor, can prevent the process.
 
By encapsulating nitrapyrin in a polyurea shell (shown here), Dow AgroSciences’ researchers developed an aqueous formulation of the enzyme inhibitor that helps prevent soil microbes from breaking down fertilizer in the soil. The technology delivers nitrogen efficiently to plants and reduces water pollution and greenhouse gas emissions.
Credit: Dow AgroSciences

Chemistry has always been an integral part of agriculture, never more so than today as farming is more dependent on fertilizers and pesticides than ever before. Agrochemicals are now designed to be more selective so they can be applied at lower rates, and they are also designed to be less toxic and less environmentally persistent.

One example is Dow AgroSciences’ Instinct, a new technology that makes more efficient use of nitrogen when it’s applied to crops. By encapsulating the ammonium monooxygenase enzyme inhibitor nitrapyrin in polymer microcapsules and applying it to fields with fertilizer or manure, Instinct helps prevent soil microbes from converting fertilizer into a form that is more likely to leach into groundwater and into streams and lakes. According to Dow, Instinct also reduces atmospheric nitrous oxide emissions from farming operations, a leading source of the greenhouse gas. For its efforts, Dow AgroSciences received the 2016 Greener Reaction Conditions Award.

Nitrapyrin, or 2-chloro-6-(trichloromethyl)pyridine, has long been used in agriculture to inhibit nitrification, according to Roberta J. Ressler, a member of the Dow team. Its use was initially spurred by findings that, of the nitrogen applied to fields as urea, ammonia, or manure that is lost, 70% of it is lost through nitrification. In this natural biological process, microbes in the soil oxidize ammonium (NH4) to nitrite (NO2), followed by oxidizing nitrite to nitrate (NO3). In soil, which is loaded with negatively charged particles, ammonium cations tend to stay put in plant root zones. But the nitrate anions are mobile and can leach away or are further broken down by microbes. Nitrapyrin disables the soil microbes, leaving more nitrogen in the ammoniacal form.

Dow has been selling nitrapyrin since 1974, Ressler notes, but until now it was only available in a formulation compatible with a “dry” fertilizer: the anhydrous ammonia form of nitrogen fertilizer. In the new approach, the Dow researchers designed an aqueous nitrapyrin microcapsule suspension that can be used with dry or liquid fertilizers.

The team’s formulation involves trapping nitrapyrin in a polyurea shell formed by the reaction between an oil-soluble polyisocyanate and a water-soluble amine. Besides improving on nitrapyrin technology, Instinct offers an alternative to coated slow-release fertilizers, which can be expensive. Dow estimates that Instinct’s nitrogen-retention abilities increased 2014 U.S. corn production by 50 million bushels while cutting U.S. nitrous oxide emissions in half, or by approximately 664,000 metric tons of carbon dioxide equivalents.

“The demand for higher crop-yield agricultural productivity continues to expand,” says Daniel R. Kittle, the company’s vice president of research and development, “and so too does the need for science-based solutions like Instinct that are focused on addressing urgent global challenges such as water quality and greenhouse gas emissions.”

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When fertilizers are applied to crops, nitrogen in the form of ammonium ions are most readily retained and used by plants. But soil microbes break down NH4+ to NO3-, which can leach into water or undergo denitrification to form the greenhouse gas N2O. Nitrapyrin, an ammonium monooxygenase enzyme inhibitor, when applied with fertilizer, significantly curtails nitrification and keeps more nitrogen available for plants.
A diagram shows how fertilizers can break down from ammonium to nitrate and nitrous oxide, reducing amount of nitrogen for plants. Nitrapyrin, an enzyme inhibitor, can prevent the process.
 
When fertilizers are applied to crops, nitrogen in the form of ammonium ions are most readily retained and used by plants. But soil microbes break down NH4+ to NO3-, which can leach into water or undergo denitrification to form the greenhouse gas N2O. Nitrapyrin, an ammonium monooxygenase enzyme inhibitor, when applied with fertilizer, significantly curtails nitrification and keeps more nitrogen available for plants.


Biocatalytic process stitches greenhouse gases into commodity thermoplastics

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Newlight Technologies’ biocatalytic process offers a sustainable route to commodity-grade thermoplastics that can compete with petroleum-based polymers.
Credit: Newlight Technologies

A flow diagram shows production route from petroleum to polypropylene and polyethylene versus a simpler route to AirCarbon polyhydroxyalkanoate.
 
Newlight Technologies’ biocatalytic process offers a sustainable route to commodity-grade thermoplastics that can compete with petroleum-based polymers.
Credit: Newlight Technologies


The sense of urgency that society now feels about tackling climate change has gotten many chemists and entrepreneurs busy trying to figure out what to do with easily captured industrial greenhouse gas emissions. The result is a growing number of clever approaches for converting one-carbon molecules such as carbon monoxide, methane, and carbon dioxide into commodity chemicals such as methanol, formate, and 2,3-butanediol, as well as incorporating them into polymers.

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A chair made with Newlight’s AirCarbon, a thermoplastic made from recycled methane emissions.
Credit: Newlight Technologies
A photo of a metal-frame chair with seat and back made from molded AirCarbon plastic.
 
A chair made with Newlight’s AirCarbon, a thermoplastic made from recycled methane emissions.
Credit: Newlight Technologies

Enter Newlight Technologies, winner of the 2016 Designing Greener Chemicals Award and Climate Change Award. Newlight’s biocatalytic process creates thermoplastics from sequestered methane and carbon dioxide. A proprietary bacterial polymerase enzyme couples carbon emissions from landfills, compost digesters, or power plants with oxygen from the air to produce polyhydroxyalkanoate polymers, which the company calls AirCarbon.

Although methods to produce this type of sustainable plastic were previously known, including some that have been commercialized, they have been limited by production costs or by polymer performance, explains Mark Herrema, Newlight’s cofounder and chief executive. For example, microbial enzymes used by other methods tend to shut down once polymer is produced, which means a large amount of biocatalyst is needed to meet production goals, making them cost-prohibitive.

Newlight’s production process avoids that issue, enabling the company to offer a sustainable plastic with commodity-grade performance that can outcompete petroleum-based thermoplastics such as polyethylene and polypropylene, Herrema contends. Those plastics require multiple production steps using oil or natural gas feedstock and metal catalysts at high temperature and pressure, leading to high capital costs. AirCarbon, on the other hand, is made from carbon emissions in a single reactor under near-ambient conditions.

“Our mission is to use greenhouse gases as a resource to replace oil-based plastics and reduce the amount of carbon in the air on a market-driven basis,” Herrema says. “This award is a testament to the extraordinary team at Newlight that has been dedicated to this cause for more than a decade.”

Since commercialization in 2013, AirCarbon has been used by Dell and Hewlett-Packard for computer packaging, Virgin and Sprint for cell phone cases, contract manufacturer KI for furniture, and The Body Shop for personal care product containers. Last year, Newlight signed a 20-year contract to supply chemical distributor Vinmar International with more than 8.5 million metric tons of AirCarbon and has licensing agreements with furniture maker Ikea and other firms to produce millions of tons more.


Yeast repurposes vegetable oil to make nylon

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Verdezyne scientists adapted yeast to develop a three-step enzymatic process for converting lauric acid derived from vegetable oil into diacids such as DDDA, which is used to make nylon and other chemicals that go into manufacturing consumer products.
Credit: Verdezyne/C&EN/Shutterstock
A diagram shows chemical conversion of vegetable oils into dodecanedioic acid, which is used to make nylon that goes into consumer products that are pictured.
 
Verdezyne scientists adapted yeast to develop a three-step enzymatic process for converting lauric acid derived from vegetable oil into diacids such as DDDA, which is used to make nylon and other chemicals that go into manufacturing consumer products.
Credit: Verdezyne/C&EN/Shutterstock

Increasingly, manufacturers are looking to derive their raw materials and feedstocks from renewable sources. Dicarboxylic acids sourced from sugar or vegetable oil are a class of compounds at the top of the list. But getting from a plant-derived sugar or oil to a diacid and then on to a commercial product still takes ingenuity.

Verdezyne received the 2016 Small Business Award for engineering a genetically modified yeast and developing an aerobic-fermentation-based technology platform to produce adipic acid, sebacic acid, and dodecanedioic acid. These three versatile diacid intermediates and their analogs are the starting materials for an array of consumer goods.

For example, dodecanedioic acid, or DDDA, is primarily copolymerized with hexamethylenediamine to make nylon 6,12 and nylon 12,12. These types of nylon are widely used in engineered plastics in automobiles and as filaments for paintbrushes, toothbrushes, and fishing line. DDDA is also used as a cross-linker for acrylic-based paints, coatings, and adhesives and as a source of diesters for lubricants and fragrances.

Manufacturers currently produce DDDA from fossil-based resources by the trimerization of butadiene followed by hydrogenation and then oxidation with nitric acid, which requires high temperature and pressure. Another DDDA route involves fermentation-based oxidation of dodecane distilled from kerosene.

Verdezyne researchers started with a Candida yeast strain originally isolated from petroleum-contaminated soil that uses alkanes as its sole source of carbon, explains Thomas A. Beardslee, the company’s vice president of research and development. The team first sequenced the yeast’s genome. Armed with that information, the scientists made genetic modifications to alter the yeast’s biochemistry, from feeding on alkanes and oxidizing them to produce energy to feeding on lauric acid derived from palm kernel oil or coconut oil. The optimized yeast uses a three-step enzyme-mediated fermentation process to oxidize lauric acid to DDDA at a rate of better than 140 g/L.

According to Verdezyne’s analysis, its Biolon-brand DDDA has a lower carbon footprint than fossil-fuel-based DDDA, and nylon made with Biolon has purity higher than performance equal to or better than fossil-fuel-based nylon. Its production occurs under ambient conditions rather than at high temperature and pressure, Beardslee notes, making it safer to produce and more energy-efficient. It also avoids using concentrated nitric acid and generating the greenhouse gas nitrous oxide as a by-product. Verdezyne has demonstrated the technology in a pilot facility and is now building a 9,000-metric-ton-per-year Biolon commercial facility in Malaysia.

“Renewable chemicals must be a central part of any broad strategy for combating climate change, and yet far too often they are left out of the discussion entirely,” says Verdezyne’s president and chief executive, E. William Radany. “This award plays a key role in raising awareness of clean chemicals.”

 
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Comments
Robert Buntrock (June 28, 2016 4:32 PM)
Re fertilizer nitrogen conservation, how "green" is the preparation of nitrapyrin and how does use of this affect the economics of this fertilizer use?
Steve Ritter (July 4, 2016 8:04 AM)
Thanks for the question. Nitrapyrin is typically prepared from methylpyridine and chlorine. At first glance, using chlorine as a reagent might not be considered very green, and neither does use of an organochlorine compound. But it depends on the alternatives. When it comes to evaluating how green a chemical product or process might be, a complete life-cycle analysis is needed to look at sourcing raw materials, the synthesis, use, and end-of-life stages, then also the toxicity and environmental impacts, and the economics. Made on a large scale, the economics for nitrapyrin likely are good overall—if using nitrapyrin to reduce the amount of fertilizer used, or to grow more food with the same amount of fertilizer, that is a green benefit. Nitrapyrin like many industrial chemicals isn’t nontoxic, but its effects depend on exposure level, and most people are not exposed to it. Nitrapyrin is broken down by microbes in the soil, so it is not considered a persistent or bioaccumulative chemical. Overall, it appears nitrapyrin comes out ahead on being green, but there could be greener technologies to come that could replace it. It has been used in agriculture since 1974.

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