Defense J.O.P. Broekman: Exploring homogeneous catalysis for the oxidation of starch

Promotors: prof. dr. P.J. Deuss, prof. dr. ir. H.J. Heeres

Abstract: Starch is an important bio-based feedstock from sources such as potato, rice, corn and wheat, produced on a massive scale worldwide. Starch oxidation is a common process to improve the properties of native starches for use in various applications such as giving viscosity to processed foods and adding strength to paper. Currently, bleach is used for the oxidation of starch on an industrial scale leading to salt waste and toxic byproducts. This thesis aimed to find alternatives to allow cheap oxidation of starch without the environmental burdens. Our approach was to use hydrogen peroxide and develop a catalyst to activate the peroxide. A manganese-based catalyst was found which was able to oxidise starch to a high degree, giving desired properties close to those achieved by the conventional process. However, small changes in the properties and the microstructure of the starches were found, requiring us to study the catalytic process in more detail. These studies revealed complex interactions of the catalyst and the starch granules on the microscale, giving further understanding of both catalytic oxidation of starch and the catalyst itself. The starches oxidised with our system showed never seen before behaviour extending the interest past the initial goal of replacing bleach. Still, with this new process, starches can be oxidised without the waste generated by the use of bleach.

Dissertation