The dehydration of lactic acid to produce acrylic acid is a renewable alternative to the production of acrylic acid from propene. Cordula Buse, Deputy Editor ChemBioEng Reviews, talks to Professor Benjamin Katryniok, University of Lille, CNRS, France, about his recent review article on the dehydration of lactic acid.
Professor Katryniok, your main research interest is heterogeneous catalysis for the upgrading of biomass. Could you please briefly explain the focus of your work to a non-specialist?
I think everyone has already heard about lactic acid. It is produced even in the human body when the muscles don’t get enough oxygen and start to convert sugar to lactate. Hence, it plays a very important role in various biochemical processes. Furthermore, as its name suggests, lactic acid is present in milk products, but also in certain fruits and vegetables and it can also be produced directly from various biomass by fermentation, thus making it an easily accessible and renewable molecule.
On the other hand, acrylic acid and its derivates are used in the manufacturing of plastics, in acrylic paints, and in various other products. The demand for acrylic acid has gradually increased in the last years to approx. 5 million tonnes. Currently, acrylic acid is produced from propene, a by-product of petroleum refining.
Today, one of the main challenges of the chemical industry is the development of new sustainable and “green” processes, taking into account the numerous environmental issues that affect our planet. Consequently, there is an interest in the production and use of chemicals obtained through environmentally friendly technologies. That is why the production of acrylic acid from biomass-derived lactic acid is of great importance.
What was the inspiration for your article about the dehydration of lactic acid?
Even if this subject has been developed in the last decades there was not any complete review on this topic in the literature. Some good articles have been, of course, published but they are almost exclusively concerned with one family of catalysts or one method of catalytic transformation. There was without any doubt a need for a more complete review dealing with the catalytic synthesis of acrylic acid via dehydration reaction and presenting the whole cycle, from catalyst design, synthesis, and material characterization to the catalytic results.
What are you currently working on and what will be the next steps on your journey?
Catalytic dehydration of lactic acid to acrylic acid still remains a challenge to be understood and controlled by researchers. As could be seen from our critical review, all aspects of the reaction have not been addressed yet. In our group, we are just beginning to wonder about the influence of conditions under which the developed catalysts have been tested. The conception of new catalysts for this reaction must undoubtedly take into account the upstream production of lactic acid if it is produced from biomass by fermentation.
There is also the question of the desired properties of active materials. Although it seems that even if the dehydration reaction should be carried out on an acid site, we assume the participation of basic sites. Do they really participate in the reaction mechanism? What is the exact mechanism of the reaction? There are still so many questions that need to be answered and I and my colleagues are working on that.
What is the broader impact of your research for the scientific community and for the general audience?
The scientific and technological concepts proposed in our research are based on the use of state-of-art chemicals and catalytic strategies for biomass transformation, by using a combination of nanomaterial engineering, chemical engineering, and heterogeneous catalysis. Such methodologies enable the development of novel products and procedures, which act on the conception of more efficient, more sustainable, and more environmentally friendly processes and products, which is one of the main ambitions of this work. Indeed, there is a clear worldwide need to increase sustainability in the industrial catalytic processes, especially in the production of fine chemicals.
Which part of your work proved the most challenging?
The most challenging part is with any doubt the design of new catalytic materials. Indeed, the development of biorefinery processes is one of the major prerequisites for establishing an economy based on bio-resources. In this context, catalysis plays a crucial role. However, unlike petro-resources whose variations in nature and composition are ‘relatively’ restricted, in the case of bio-based substrates, different compounds with different functional groups are present. A range of specific materials and processes must be developed to selectively convert each fraction to the desired product. This involves, in particular, the development of many catalytic water-tolerant materials that can be easily recycled. Innovative solutions must be developed for that.
Are there any other topics your research group is investigating?
Currently, I am involved in the development of new advanced catalysts for biomass transformation. My research is focused especially on the hydrogenation, dehydration, and oxidation of bio-based compounds using heterogeneous and hybrid materials and their combinations under the efficient and novel concept of fully integrated hybrid catalysis. Furthermore, we are actually working on multi-component catalysts with tailored properties for eco-efficient products and processes.
Is there anything else you would like to add?
Yes, I would like to encourage all young students reading our work to take time to understand not only the chemistry or catalysis but also chemical engineering or bioprocesses. Actually, researchers are working on the interface between all sciences and sometimes ideas that seem to be wrong in one field are perhaps breakthrough innovation for another.
Thank you very much for the interview!
The article they talked about
- Dehydration of Lactic Acid: The State of The Art,
T. Bonnotte, S. Paul, M. Araque, R. Wojcieszak, F. Dumeignil, B. Katryniok,
ChemBioEng Rev. 2018, 5, 34–56.