Catalysis with renewables & platform chemicals
Dr. Sandra Hinze
The chemical industry has been operated on an oil-based infrastructure for a very long period of time. This era is now coming to an end as the supply of fossil resources is limited. Therefore, research on the conversion of renewable feedstocks into bulk and fine chemicals has gained extraordinary importance. Our contribution to this research area focusses on the catalytic conversion of inedible plant material, such as cellulose, lignin or lignocellulose. These materials can be converted into a number of platform chemicals, such as ethanol, levulinic acid, 5-hydroxymethylfurfural (HMF) or furfural. Using mostly homogeneous catalysis we want to convert these platform chemicals into raw materials for polymers, such as butadiene, caprolactam, adipic acid or adiponitrile. Below we show some examples of the conversion of Levulinic acid and 2-Hydroxymethylfurfural to give an impression of the group’s approach and expertise.
Levulinic acid (LA) as platform chemical
Levulinic acid is the only platform chemical which can be made directly from lignocellulose (wood, agro waste) by treatment with dilute acid at high temperatures (Scheme 1). Yields are around 55-70% LA. For comparison, bioethanol is obtained with a yield of 40%. The potential of LA as platform chemical was proven by a process developed for the production of adipic acid from LA at DSM (Scheme 2) [de Vries and co-workers WO 2013/107904, WO 2013/107902, WO 2012/131028, WO 2012/131027].
We aim to convert levulinic acid into a range of other bulk and fine chemicals using homogeneous catalysis.
5-Hydroxymethylfurfural (HMF) as platform chemical
At the University of Groningen, where Hans de Vries has a part-time appointment as Professor Homogeneous Catalysis, a process was developed for the conversion of HMF into caprolactam in only four steps [de Vries, Heeres and co-workers, Angew. Chem. Int. Ed. 2011, 50, 7083-7087]. This shows the huge potential of HMF as platform chemical, as the current process starting from benzene requires seven steps.
Generally, HMF can be made in high yield from fructose by treatment with acid under water-free or two-phase conditions. However, a route is desired from glucose but preferably from lignocellulose for a breakthrough of HMF as platform chemical. The isomerization of glucose to fructose is a considerable bottleneck of the process as it is usually either done enzymatically (expensive) or by using toxic chromium salts. Therefore, we aim to develop new homogeneous catalysts for the isomerization step.
For an overview of the use of homogeneous catalysis in the conversion of renewables and platform chemicals, see: P.J. Deuss, K. Barta, J. G. de Vries, Cat. Sci. Technol., 2014, 4, 1174-1196.