Dr. Elsje Alessandra Quadrelli is a CNRS researcher in the field of catalysis and organometallic chemistry and head of the sustainable development chair of École Supérieure de Chimie Physique Électronique de Lyon (CPE Lyon), France. Professor Gabriele Centi is a professor of Industrial Chemistry at the University of Messina, Italy. He is a former President of the European Federation of Catalysis Societies and was coordinator of the European Network of Excellence on Catalysis, IDECAT.

Together, they have guest edited the ChemSusChem special issue on Green Carbon Dioxide which focuses on emerging technologies for large-volume CO₂ recycling. They talk to the ChemViews magazine about how the perception of CO₂ has changed, the special issue, and the future of CO₂ recycling. 

Today CO₂ is often considered as a devil molecule. When and how did it start that CO₂ was considered as a resource?

Alessandra Quadrelli: This separation between CO₂, being a resource molecule and CO₂ being considered a devil-turned-resource molecule, is interesting.

CO₂ has always been a resource, given Nature’s capacity of transforming it into sugars and, more widely, into biomass. Chemists have long considered it as a resource for their own man-made processes: the Kolbe–Schmidt industrial process from CO₂ to sodium salicylate (precursor to aspirin and other reagents) is almost two centuries old now; urea-based fertilizers, that are central to the agricultural production, consume over 100 MT of CO₂ yearly. These uses of CO₂ as a resource therefore well predate the “devil” label.

CO₂ was identified by the lay-person as the molecule to take down — sometimes literally, for example, by capture and storage strategies — when climate change and the connected alarms on increasing of atmospheric CO₂ levels came to the forefront of societal concerns. To put a reference on the timeline, let’s recall that Al Gore’s movie An Inconvenient Truth, with the infamous sequence on the CO₂ levels skyrocketing behind the speaker’s podium, came out in 2006. This anathema on the molecule was not necessarily shared by chemists. Good proof is the biennial International Conference on Carbon Dioxide Utilization (ICCDU). This multi-disciplinary forum on chemical and biochemical innovations in fundamental and applied aspects of CO₂ utilization has been running since 1991, and the latest edition took place in June of this year in Dijon, France, which succesfully attracted hundreds of particpants.

What is maybe emerging more clearly now, is that the established body of work around CO₂ chemistry can become a precious asset also in the context of CO₂ management strategies. The novelty, maybe, is the awareness that CO₂ chemical recycling with sustainable energy sources can be, simultaneously, a desirable environmental solution, a viable business opportunity, and a tremendous research playing field.

Gabriele Centi: Reusing CO₂ to make fuels or chemicals, when using renewable energy in the process, is the best option available today to introduce renewable energy in the energy and chemical production chains, and thus the reuse of CO₂ is becoming a strategic issue towards the goal of achieving a resource efficiency, one of the flagship initiatives of the Europe 2020 Strategy. This was one of the key concepts presented in the special ChemSusChem issue. The relevance of which is thus going beyond the science & technology aspects. It is shown how science & technology enables the socio-political decisions to create a future sustainable society.

What is the state-of-the art of CO₂ recycling into fuels and chemicals?

Alessandra Quadrelli: It is almost impossible to provide an extensive list given the activity in the field. I think the special ChemSusChem issue gives some feeling for the richness of the topics involved. These range from mineral carbonation to reagent in organic chemistry (to carbonates, acrylates, carboxylic acids, polycarbonates and polyurethanes, etc.), from fuels derived from chemical reduction (methanol, formic acid, methane, DME, etc.) to value-added bioroutes to food supplements and possibly biofuels.

Gabriele Centi: It is important to mention that the ChemSusChem issue does not only give an overview of the current state-of-the-art, but also looks at carbon dioxide as a key element for the future of chemical industry. For example, one of the concepts presented regards how CO₂ could be converted to light olefins, the brick for all petrochemistry, at a competitive cost with respect to the current very energy-intensive process, when H₂ from renewable sources is available at a cost below about 2–3 €/kg. Current technologies are not so far from this value, and thus within a decade it will be possible to develop a CO₂-based chemistry.

Where is the field heading?

Gabriele Centi and Alessandra Quadrelli: We see several fields looking with interest at CO₂ chemistry, and each has a different perspective.

One point of view emerges from the large CO₂ emitters, e.g., the cement industry. Their challenge is to dispose of massive amounts of CO₂ in a cost-efficient way and/or avoid large amounts of CO₂ emission. To give a feeling of the size: three billion tons of Portland cement are produced yearly, and for each ton of cement produced, roughly one ton of CO₂ is emitted … the scale of the issue is just gigantic. The challenges are tremendous, therefore, for finding cost-efficient ways in this very mature field where the price of the starting materials are very low. The challenges are also technically very high for producing ‘greener’ materials, such as ‘green cement’, for which adherence to the sector standards is a tough nut to crack.

One different point of view is from manufacturers of organic chemicals that include the whole CO₂ molecule in their products like urea or organic carbonates. The field is rather advanced, with several products hitting the markets. Several incentives push them: a relatively energy accessible chemistry, for example:

• Carbonatation, the whole transfer of CO₂ moiety, is much less energy demanding than carbonylation, the transfer of a CO moiety by energy intensive reduction.
• The possibility of replacing toxic phosgene as carbonyl source in established industrial processes
• The availability of several catalytic systems already, etc.

The challenges lie in the development of new shorter catalytic pathways, for example, for directly obtaining industrially relevant carbamates, isocyanates, etc.

The fuel sector also looks closely at CO₂ chemistry. This sector is possibly one of the most strategic since the chemical industry is a tributary of the energy one. To put it quickly and coarsely: petrochemistry is the starting point to most chemistry intermediates now, also because we use oil to make our world go round. If we were using biomass — just to give one example — to power our energy needs, the cheapest starting chemicals would probably come out of the biorefineries. Making fuels out of CO₂ would be a tremendous asset in terms of circular carbon economy, but not necessarily in terms of carbon storage, we agree. The methanol economy concept, so strongly supported by Professors Olah and Surya Prakash at the University of South California, USA, is a good way to help conceptualize the fundamental societal changes that such a switch would bring. In this field, the biggest challenges in fuel-from-CO₂ probably reside in developing technology with renewable energies — if possible from the sun which would open the way to ‘solar fuels’ — and, as an intermediary challenge, in providing drop-in fuel that will facilitate the transition.

Many hopes and investments have also resided in Biotechs, for example, use of algae for synthesis of biofuels. The challenges are well summarized in the “fatter, faster, cheaper, easier” goals identified by W. Thurmond in his studies on algae biofuel commercialization. Many leverage points are present in this field such as white biotechs, photobioreactor engineering, processing engineering, … and, therefore, many possible futures.

And finally, beyond the strictly science-related orientations, there is a need to develop new tools to help critical assessment of the field; for policy orienters for example, but also investors or researchers. It would be nice to be able to develop common benchmarking and analysis tools such as life cycle assessment (LCA) analyses or other adequate multicriteria methodologies. We have to find a way to globalize, or at least coordinate, this aspect of the field of large scale CO₂ recycling to fuels and materials if we want it to emerge as a recognized and efficient environmental solution, business opportunity, and research frontier.

Where do you see our raw material supply coming from in 50 years time?

Alessandra Quadrelli and Gabriele Centi: Fossil fuel, mostly: the end of our current energy supply system is not tomorrow. But to use a popular quote, which apparently belongs to Saudi Oil Minister, Sheikh Zaki Yamani, back in the 1970s: “The stone-age did not end because we ran out of stones, the oil age will not end because we run out of oil.” In this context, where it is not immediate scarcity, but political choice that will accelerate transition to solutions other than fossil fuels, many options are surfacing of an extraordinary diversity. Some are very site specific, such as the use of Icelandinc geyser power by Carbon Recycling International to obtain MeOH from CO₂, others are extremely ambitious world-level collaborations, i.e., the ITER project around nuclear fusion, and still others are immensely diffuse and pursued in the scientific community, in particular, how to improve efficiency of solar energy harvesting. Probably a combination of the most successful among these and other energy-related routes will contribute to the new energy mix which will be our supply. Innovations, provided inter alia by proactive funding policies and investments, will eventually make the difference.

Will we soon see industrial applications?

Gabriele Centi and Alessandra Quadrelli: We already have many, as we tried to show in the Review Carbon Dioxide Recycling: Emerging Large-Scale Technologies with Industrial Potential where we identified 26 chemicals industrially produced from CO₂. The frontier is how many will reach their full potential and will be able to be cost-efficient with sustainable energy sources and acceptable overall CO₂ balances.

The amount of energy to re-use CO₂ is large and results in production of new CO₂. Wouldn’t this energy balance problem limit CO₂ recycling to a niche?

Alessandra Quadrelli: Right now, some technologies are already CO₂ neutral.

Gabriele Centi: But you are right, the use of renewable energies is central for applications that want to impact meaningfully on CO₂ emission strategies.

You edited the Special Issue “Green Carbon Dioxide” of the journal ChemSusChem. How did you decide which authors should contribute?

Alessandra Quadrelli and Gabriele Centi: As chair (AQ) of the CO₂ Forum 2010 on large-volume CO₂ recycling, which took place in September 2010 at the CPE Lyon School of Engineering, France, and as keynote-address speaker (GC) of the workshop CO₂: From waste to Value organized on March 30, 2011 in Brussels, Belgium, by the European Commission, we had a chance to invite and listen to many of the top players in the field. The events were also the occasion of active exchanges between the panelists and the meeting attendants. Most of the contributions present in the special issue originated from these contributions.

What is it like to hold the finished issue in your hands?

Alessandra Quadrelli: I always have a soft spot for hard copies of journals, even with the formidable access we have now through the internet. While a comprehensive literature search on a specific topic always goes through the keyboard, I still indulge in flicking through paper pages to see what is emerging, what is going on in the chemistry world. I hope other people will have the “yummy” feeling of “let’s see what’s cooking in CO₂ recycling” while browsing the issue. I keep one right on my desk.

Have you done other projects together?

Gabriele Centi: I was head of the European network of excellence Integrated Design of Catalytic Nanomaterials for a Sustainable Production (IDECAT) from 2005–2009 and Alessandra was co-responsible of the workpackage on training and education, that gave us numerous occasion to work together.

How is your research connected to CO₂ recycling?

Alessandra Quadrelli: From my side very little, actually. I am a full time CNRS researcher and I mostly study N₂ and SiH₄ activation on metal-funtionalized silica and MOF materials. I came to the field of CO₂ recycling as head of the sustainable chair of the French engineering school CPE Lyon. At the launch of the chair in 2009, we asked ourselves what action would show our chemical engineers-in-training that research, business, and policy are connected and that they have a role to play in their future careers. Our chemical engineers-in-training should be excellent chemists, but should also be aware of capacities and limitations of science & technologies, at the service of society’s needs and expectations, and able to face the increasingly more complex challenges (there included a credible business-plan …). Following the very appreciated suggestion of C. Fussler, former Vice President of Dow Chemical in Europe and Special Advisor of the UN Global Compact of which he directed the Caring for Climate program, we selected CO₂ recycling as THE topic for “embodying” this approach and launched the two day open conference “CO₂ forum”. Its second edition will take place in Lyon September 27–28, 2012.

Is there anything else you would like readers of the ChemViews magazine to know?

Alessandra Quadrelli: I feel chemistry is at the same time an awe-inspiring science and a real down-to-earth craftsmanship that can truly help society. I hope as chemists we succeed in making this more self-evident around us.

Thank you very much for the interview!

Dr. Elsje Alessandra Quadrelli studied chemistry at the Scuola Normale Superiore di Pisa, Italy, and gained her Ph.D. from the University of Maryland, USA. She performed post-doctoral research at the universities of Cambridge, UK, and Pisa, Italy, before becoming a CNRS researcher in the field of catalysis and organometallic chemistry. She is the head of the sustainable development chair of École Supérieure de Chimie Physique Électronique de Lyon (CPE Lyon), France, and co-chairs the decarbonated energies workgroup of the French competitive cluster AXELERA.

Her current research interests are N₂ and SiH₄ activation by silica-supported organometallic complexes and by novel functional materials, such as metal organic frameworks.

Professor Gabriele Centi studied industrial chemistry at the University of Bologna, Italy. He was associate professor in Chemical Reactor Engineering at the University of Bologna until 1996 when he joined the University of Messina, Italy, as full professor of Industrial Chemistry. He is a former President of the European Federation of Catalysis Societies, and was co-ordinator of the European Network of Excellence on Catalysis IDECAT. He is co-Chairman of the Editorial Board of ChemSusChem.

His research interests lie in the development of industrial heterogeneous catalysts for sustainable chemical processes, environmental protection, and clean energy.

Selected Publications

Quadrelli

• Emerging large-scale technologies around CO₂ recycling with industrial potential
  E. A. Quadrelli, J.-L. Duplan, G. Centi, S. Perathoner
  ChemSusChem 2011, 4, 1194-1215.
  DOI: 10.1002/cssc.201100473
• Heterolytic cleavage of ammonia N–H bond by bifunctional activation in silica-grafted Ta(V) imido amido surface complex. Importance of the outer sphere NH₃ assistance
  E. Gouré, P. Avenier, X. Solans-Monfort, L. Veyre, A. Baudouin, Y. Kaya, M. Taoufik, J.-M. Basset, O. Eisenstein, E. A. Quadrelli,
  New J. Chem. 2011, 35, 1011-1019.
  DOI: 10.1039/C1NJ20032A
• Synthesis and Stability of Tagged UiO-66 Zr-MOFs
  M. Kandiah, M. Hellner Nilsen, S. Usseglio, S. Jakobsen, U. Olsbye, M. Tilset, C. Larabi, E. A. Quadrelli, F. Bonino, K. P. Lillerud
  Chem. Mater. 2010, 22(24), 6632-6640.
  DOI: 10.1021/cm102601v
• On silsesquioxanes’ accuracy as molecular models for silica- grafted complexes in heterogeneous catalysis
  E. A. Quadrelli, J.-M. Basset
  Coord. Chem. Rev. 2010, 254(5-6), 707-728.
  DOI: 10.1016/j.ccr.2009.09.031
• Dinitrogen Dissociation on an Isolated Surface Tantalum Atom
  P. Avenier, M. Taoufik, A. Lesage, X. Solans-Monfort, A. Baudouin, A. de Mallmann, L. Veyre, J.-M. Basset, O. Eisenstein, L. Emsley, E. A. Quadrelli
  Science 2007, 317, 1056-1060.
  DOI: 10.1126/science.1143078

Centi

• Can We Afford to Waste Carbon Dioxide? Carbon Dioxide as a Valuable Source of Carbon for the Production of Light Olefins
  G. Centi, G. Iaquaniello, S. Perathoner,
  ChemSusChem 2011, 4, 1265-1273.
  DOI: 10.1002/cssc.201100313
• CO₂-based energy vectors for the storage of solar energy
  G. Centi, S. Perathoner,
  Greenhouse Gases: Sci. Technol. 2011, 1, 21-35.
  DOI: 10.1002/ghg3.3
• Solar production of fuels from water and CO₂
  G. Centi, S. Perathoner, R. Passalacqua, C. Ampelli,
  In Carbon-Neutral Fuels and Energy Carriers, N.Z. Muradov, T. N. V., Ed. CRC Press (Taylor & Francis Group): 2012; pp 291-323.
• Towards Solar Fuels from Water and CO₂
  G. Centi, S. Perathoner,
  ChemSusChem 2010, 3, 195-208.
  DOI: 10.1002/cssc.200900289
• Creating and mastering nano-objects to design advanced catalytic materials
  G. Centi, S. Perathoner,
  Coord. Chem. Rev. 2011, 255, 1480-1498.
  DOI: 10.1016/j.ccr.2011.01.021

Selected Awards
Quadrelli

• Pelczar Award form University of Maryland at College Park, 1998

Centi

• Award F. Durante on Nanotechnology, 2010
• UOP 2010 lectureship
• Societé Chimique de France French-Italian Prize, in recognition of distinguished works in industrial chemistry and sustainable processes, 2009
• Eminent Visitor Award, Catalysis Society of South Africa, 2007
• Award from Federchimica (Italian Society of Chemical Industries) for the innovative research on environmental catalysis, 1993

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  ChemSusChem 2011, 4 (9).