Heterogen katalysierte reduktive Umsetzung von biogenen Carbonsäuren zu 2-Pyrrolidonen und deren Vinylierung zu Monomeren

• Heterogeneously catalyzed reductive conversion of biogenic carboxylic acids to 2-pyrrolidones and their vinylation to monomers

Louven, Yannik; Palkovits, Regina (Thesis advisor); Pich, Andrij (Thesis advisor)

Aachen : RWTH Aachen University (2021)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2021

Abstract

Biomass will play an important role in the chemical value-added chain to reach the climate goals and tackle climate change. However, processes to convert biomass efficiently into valuable chemicals must be established to make biorefineries compatible to the fossil based chemical production. Thus, this work investigated a two-step process for the upgrading of bioderived itaconic, succinic and levulinic acid to value-added N-vinyl-2-pyrrolidone (NVP) monomers. The first step in the conversion of dicarboxylic acids to 2-pyrrolidones comprises a one-pot amidation/ cyclization of the acid and reduction of the in-situ formed imide. Investigation of the reaction network revealed temperature-driven amidation and dehydration/ cyclisation steps to finally form an imide, which may be reduced by a catalyst to 2-pyrrolidones. The reactions were carried out in concentrated aqueous phase with ammonia as nitrogen source and hydrogen as reducing agent. Carbon supported ruthenium and palladium materials were identified to efficiently catalyse the reaction, as 3- and 4-methyl-2-pyrrolidone were formed with yields of 90 %. Palladium catalysts could be applied at lower hydrogen pressures and were shown to be more versatile, as they can also convert levulinic acid to 5-methyl-2-pyrrolidone with yields of >96 %. Furthermore, STEM and CO-Pulse analysis have shown, that the imide reduction is structure sensitive, as the palladium nanoparticle size strongly influences the catalytic activity. With stability tests, up-scaling and continuous production in a CSTR, a general feasibility of the process for an industrial application was shown in this work. In the second step, the 2-pyrrolidones were converted with acetylene to N-vinyl-2-pyrrolidones. This industry-known process uses KOH as catalyst, 130-170 °C and 15-25 bar. It was shown, that the methyl-substituted 2-pyrrolidones synthesized in this work can be converted under similar conditions with similar yields of 80 %.Yet another alternative to produce NVP from biogenic acids alternative is the conversion of 2-pyrrolidones with cyclic carbonates to N-2-hydroxalkyl-2-pyrrolidones which may be dehydrated to NVP. With the KOH catalysed reaction, yields of up to 70 % were reached at 170 °C.