The research of Prof. Dr. P. J. Deuss focusses on the conversion of sustainable resources using catalytic technologies for a society that reached a high level of circularity. The main focus is on closing the current unsustainable carbon cycle that relies heavily on fossil feedstocks. This is done by developing fundamental insight into the (chemical) structure and reactivity of complex alternative carbon sources such as inedible lignocellulosic biomass residues and mix plastic waste streams. Here detailed characterization of the chemical structure is linked to efficient catalytic processing technologies ranging from the application of mild enzymatic and acid-base catalysis to high temperature catalytic pyrolysis and hydrotreatment technologies. Here, a combination of realistic crude streams and model compounds/mixtures are applied. The insight into reactivity is then used to develop integrated catalytic processes that combine separation with conversion setps. An example is the development of flow-through extraction methodologie for the separation of ligncellulose components that allow their separate utilization as bio-polymers or bio-based chemicals.