Stepping stones in CO₂ utilization Towards process development of oxalic and glycolic acid monomers

Science shows that the global climate is changing and that anthropogenic greenhouse gas emissions, mainly CO₂, are largely to blame. Consequently, we need to ban as much fossil-based carbon from our lives and atmosphere as possible. Using CO₂ as a feedstock will be a requirement for meeting our ambitions of a circular future and staying within the planetary boundaries. The work in this thesis is part of the OCEAN (EU Horizon 2020) project in which we develop a new route from CO₂ to polymers. At the center of this route is oxalic acid and its role as a polyester monomer and new platform to produce chemicals and other monomers. We introduce the opportunities of oxalic acid and assess how it can be produced sustainably from renewable sources. In the following five chapters 2-6 we investigate the production of oxalic acid from formate. We first provide an overview of the reaction (Ch.2), introduce better catalyst for the reaction (Ch.3), find ideal reaction conditions using a response-surface-modeling approach (Ch.4), successfully couple formate with CO₂ in ch.5, and study the mechanism in detail in a joint effort of experimental and molecular dynamic modeling (ch.6). In the last three chapters 7-9 we study the selective catalytic reduction of oxalic acid to glycolic acid. We screen suitable known and commercial catalysts for the reduction reaction (Ch. 7), establish an improved continuously operating process (Ch.8), and develop improved, highly selective multi-metal catalysts with higher stability in chapter 9.