Innovative Processes for the Catalytic Liquid-Phase Oxidation of C6-Based Substrates

This Thesis deals with the results of different research topics aimed at the development of innovative, catalytic liquid-phase oxidation processes. All of them are characterized by the use of C6-based substrate and by targets which may fit the aim of a more sustainable industrial chemistry. First, the oxidative cleavage of 1,2-cyclohexanediol to adipic acid was studied. This is an alternative synthesis of an important chemical intermediate which is produced by means of a process which holds serious drawbacks from the economic and environmental point of view. The reaction was carried out in water, with heterogeneous catalysts and using molecular oxygen as oxidant, obtaining high selectivity with Au-based catalysts. The same supported active phase was used for the oxidation of D-glucose to glucaric acid (also an intermediate for the synthsis of adipic acid) with molecular oxygen. This is an important example of a reaction starting from a substrate which is obtained from renewable resources, and that can be transformed into high added-value bio-based chemicals. Thereafter, the epoxidation of cyclohexene with Nb-based catalysts and hydrogen peroxide was studied. This study is an interesting case of catalyst design, aimed at the investigation of the molecular mechanism for the development of a more selective catalysts. Finally, the oxidation of maltodextrins and starch was studied. The goal was to investigate on a a process with hydrogen peroxide or molecular oxygen as the oxidants, testing both homogeneous and heterogeneous catalysts, with the aim to produce molecules able to replace those which are currently synthesized with less “green” processes.