Catalyzing the Circular Economy: Challenges and Opportunities
Oct. 14, 2024
10 min read
In This Article
This article discusses three areas of catalysis in need of development for a circular economy:
and the systemic approach essential for improving progress on circularity.
Catalysts have played a key role in the development of the chemical industry and should be the driving force for the creation of a circular economy.
That’s the conclusion of a commentary paper written by a team of chemical engineers, chemists and environmental scientists from Australia and the United States published in a recent issue of the sustainability journal One Earth.
The authors note that while the chemical industry contributes US$5.7 trillion to the global economy and sustains 150 million jobs worldwide, it remains the largest industrial energy consumer and the third-largest emitter of direct CO2 emissions globally.
Moreover, its operations have led to significant water contamination and the release of toxic chemicals into the environment, perpetuating a cycle of ecological harm.
"Catalytic processes could minimize reliance on finite fossil fuels and curb CO2 emissions significantly by harnessing agricultural, municipal, and plastic waste as feedstocks,” says Adam Lee, co-lead author of the paper and professor of sustainable chemistry at Griffith University in Queensland, Australia.
"This feedstock transition not only mitigates environmental damage but also addresses vulnerabilities in the industry's supply chain, which are susceptible to geopolitical and natural disruptions," he adds.
The authors highlight several cross-industry catalyst innovation initiatives underway that are showing promise.
One is Kalundborg Symbiosis in Denmark. Since 1972 this partnership of nine public and private companies has been working on an industrial park to develop circular approaches to production. Today, Novo Nordisk, Equinor Refining and Statoil are among the companies operating there.
Leveraging Biomass
A comprehensive review in Clean Technologies and Environmental Policy summarizes current advances in liquid biofuel production and solid catalysts prepared from waste biomass, as well as their advantages, drawbacks and statistical data.
The authors, from chemical engineering and chemistry departments at universities in Mexico and Colombia, offer an extensive perspective, covering conventional methods and cutting-edge techniques, such as biochemical and thermochemical biomass conversion technologies — hydrolysis, fermentation, pyrolysis and gasification — to produce bioalcohols, biodiesel, renewable diesel, bio-jet and bio-oil (Figure 1).
They also analyze the preparation of heterogeneous catalysts using residual biomass and different synthesis routes and their role in biofuel production.
The article notes sustainable biofuels production depends on feedstock, reagents, processes and technologies, all of which have different social, economic, environmental and political impacts.
The article emphasizes that a successful circular economy hinges on ramping up biofuel production using an effective waste-to-wealth strategy. This requires input from various fields of expertise. However, the authors note that society is still a long way from making this a reality.
These issues were the focus of the annual European Biomass Conference and Exhibition (EBCE) that took place in Marseille, France, in late June.
While acknowledging that strong bonds forged between the research and academic community and industry are helping to close knowledge gaps, the EBCE heard that serious hurdles stand in the way of large-scale advanced biofuel plants — as highlighted by a spate of recent closures.
In February, Enerkem Alberta Biofuels announced the closure of its biofuels plant in Edmonton, Alberta. The plan was to transform garbage that couldn’t be recycled or composted into biofuels.
The facility would have generated enough biofuels to supply over 400,000 cars per year running on a 5% ethanol blend.
"We felt we had reached our main objectives, which was to demonstrate this technology at commercial scale," Chornet said in an interview with CBC News. "Now we are retiring this facility."
Similarly, Clariant has closed its bioethanol plant in Podari, Romania, and downsized related activities in Germany. German newspaper Frankfurter Allgemeine Zeitung reported that technical problems with processing raw materials at an industrial scale were to blame.
The company planned a 50,000 t/yr plant using its proprietary Sunliquid technology to produce cellulosic ethanol from wheat and other cereal straw from local farmers. Sunliquid uses enzymes to break down lignocellulose from plant fibers.
Nevertheless, there are opportunities.
Both Evonik and BASF are upping their production capacities for sodium methylate in South America. Sodium methylate is a catalyst designed to promote higher yields and lower costs during biodiesel production.
In Evonik’s case, the plan is to increase production capacity at its Rosario plant in Sante Fe, Argentina, by 50% to 90,000 t/yr and to significantly increase biodiesel productivity and reduce production costs across South America.
The announcement is of particular importance to the region due to the Brazilian government’s recent increase of mandatory quotas for blending fossil diesel with 15% biodiesel in 2025. It also aligns with the objectives of New Industry Brazil, which aims to boost the national industry and expand the share of biofuels in the transportation energy mix.
BASF, too, is upping capacity for sodium methylate production at its site in Guaratinguetá, Brazil, to 90,000 t/yr (Figure 2).
Polymer Posers
Despite the industry’s progress with catalysts to recycle and reuse polymers, significant hurdles remain to creating a genuine circular economy.
These include the need for milder reaction conditions, more robust catalyst design, selective product yields, and experimental and feedstock standardization.
Researchers from the Artie McFerrin Department of Chemical Engineering, Texas A&M, College Station, Texas, take aim at these in a Chem Catalysis review. They note that experimental standardization is required so results obtained by different experimental and analytical methods can be compared and contradictory results avoided. This, they say, also is a problem inherent to both biomass and plastic conversion.
Uniformity in catalyst characterization and reporting is lacking, as is catalyst-to-feed ratio.
Selectivity and yield are significant challenges, too. While high selectivity is desirable, catalysts also need to be versatile for mixed feedstocks. Catalysts are currently being designed for substrate specificity. As such, highly specific catalysts cannot effectively convert mixed post-consumer plastic streams, the Texas A&M research team writes.
Then there is the issue of process design for upcycling plastics. For example, hydroconversion is efficient for upcycling polyolefins, while solvolysis and solvent extraction are efficient for upcycling condensation polymers, such as polyesters and composite plastic materials, respectively.
Plastic feed streams typically come with a variety of polymer components, all with different impurities and additives, and the level of contamination of the feed can vary drastically. An amalgam of processes and methods will be necessary to effectively handle this plastics problem, they suggest.
As with chemical processes in general, upstream and downstream processing can prove critically expensive. For reactions with either gaseous or solvent reagents, both require separation processes to extract the hydrocarbon products from the catalyst and/or solvent. Thus, process design and selection must include a holistic perspective of the processes accompanying the core depolymerization reaction.
One solution proposed is versatile catalytic processes to handle mixed streams. Series reactors with discrete catalyst beds may be applied to sequentially process the mixed substrate. In addition, solvent-assisted separation of a mixed plastic feed can be done before the catalytic reaction.
As such, say the authors, a careful balance must be struck between reaction conditions and downstream/upstream separation techniques.
Remediation
As noted by the Texas A&M chemical engineers, one of the biggest environmental challenges for the circular economy is what to do with composite waste.
Técnicas Reunida, an engineering and infrastructure development firm for the oil and gas industry, has launched a project called COMAR to develop strategies and technologies to help.
Broadly, the Madrid, Spain-based company wants to establish innovative routes for the reuse and recycling of waste coming from composites, striving to minimize energy consumption and maximize the properties of the recovered fibers for use in the construction, wind energy and transportation sectors.
It also wants to improve the sustainability of the composite industry through the revaluation of byproducts and provide a waste valorization strategy for each application.
The emphasis is on developing new recycling techniques based on pyrolysis and solvolysis and reducing the environmental impact of both processes through researching the use of catalysts.
In terms of catalytic pyrolysis technology applied to the recycling of composite materials, COMAR has two fundamental objectives. First, the company is looking to improve operating conditions to reduce processing temperatures and energy consumption. It’s also aiming to obtain higher value-added liquid pyrolysis products for applications as fuel or as precursors for high-interest chemicals, such as phenol, styrene or the BTX aromatic hydrocarbons, among others.
For liquid fraction valorization, COMAR will collaborate with Repsol, acting as an external advisor, with the aim to tailor the composition and performance of these fractions to market needs.
Key Takeaways
- Catalyst's Role: Catalysts are critical for advancing a circular economy, particularly in biomass utilization, polymer recycling, and pollution remediation, helping reduce fossil fuel reliance and CO2 emissions.
- Challenges in Polymer Recycling: Creating a circular polymer economy faces challenges like needing milder reaction conditions, improved catalyst designs, and standardization of experimental processes.
- Collaboration for Circularity: Partnerships between industries, governments, and research institutions are essential for overcoming hurdles and building a sustainable, circular economy.
Rethinking the Circular Economy
A further note of caution comes from a July whitepaper by research consultancy Wood Mackenzie. The authors of the report, Waste to wealth: Unlocking circular value chains, argue that more systemic thinking is needed.
In particular, with nascent, pre-commoditized markets typical of circular value chains, such as biofuels, transparency is lacking, presenting commercial challenges to businesses trying to make progress on circularity, among them.
The paper notes that international oil companies, technology companies and waste-management firms all operate with different capital bases, risk appetites and cashflow needs. This complicates expectations about what “fair value” looks like.
Without a clear route to value, waste-processing companies and new technologies will not be induced to bring supply to the market. Moreover, there are operational challenges for companies adopting circular business models.
For starters, new systems need to be put in place to track material flows, and staff will need to be trained to act in ways that promote the value chain as a whole, write report authors Guy Bailey, head of Wood Mackenzie’s oils and chemicals markets, and Husam Taha, principal analyst for plastics sustainability at the Edinburgh, Scotland-based firm.
Sales and procurement teams, for example, need to operate differently when success depends on the whole value chain rather than just their own business, they note.
The authors add that the stuttering progress toward circularity at the macro level suggests that the essential partnerships, joint ventures and vertical integration needed for success are not being widely adopted.
It’s not all doom and gloom, however. The authors point out that initiatives already in play show that these approaches are possible across different value chains and that their application can pave the way for a more circular, sustainable economy.
Lyondell Basell is singled out for its ambitious target for boosting circularity in plastics targeting 2 million metric tons of recycled plastic production in 2030 — an increase of 1,500% from 2023.
The company is praised for its joint venture with French waste management company Suez and investments in other waste management and technology companies as it seeks to build capacity 60-fold.
“Boosting recycling offers a means of reducing fossil-fuel extraction and adding value to a waste stream to prevent its leakage into the environment,” Bailey and Taha write.
They cite Eni, Rome, Italy, for its ambitious plan to expand biorefining capacity from 1.7 million t/yr in 2023 to 5 million t/yr by 2030, while investing in vertical integration into the agricultural sector in Africa.
“Recognizing that its capital and expertise could be used to benefit farmers in the region, Eni has helped source land that does not compete with food production and provides security of income to farmers through its long-term feedstock needs,” the report notes.
Nevertheless, they are keen to emphasize that the case studies should not be taken as templates:
“Joint ventures are not ‘the solution’ to recycling, not all refiners should invest in farming and e-waste will require more than the closer economic partnership (CEP) arrangement to drive circular outcomes in the future,” the authors note. “What they do show is that adopting the right forms of value-chain relationship — driven by the needs of the company and the value chain — can serve to introduce coordination, laying the foundation for circular value chains to grow together.”
About the Author
Seán Ottewell
Editor-at-Large
Seán Crevan Ottewell is Chemical Processing's Editor-at-Large. Seán earned his bachelor's of science degree in biochemistry at the University of Warwick and his master's in radiation biochemistry at the University of London. He served as Science Officer with the UK Department of Environment’s Chernobyl Monitoring Unit’s Food Science Radiation Unit, London. His editorial background includes assistant editor, news editor and then editor of The Chemical Engineer, the Institution of Chemical Engineers’ twice monthly technical journal. Prior to joining Chemical Processing in 2012 he was editor of European Chemical Engineer, European Process Engineer, International Power Engineer, and European Laboratory Scientist, with Setform Limited, London.
He is based in East Mayo, Republic of Ireland, where he and his wife Suzi (a maths, biology and chemistry teacher) host guests from all over the world at their holiday cottage in East Mayo.
Sign up for Chemical Processing Newsletters
Get the latest news and updates.