Bio-based monomers are synthesized in a two-step process starting from common platform chemicals. The featured sequence of heterogeneously-catalyzed reduction and gas phase dehydration makes for a promising alternative to traditional Reppe chemistry.

Succinic acid is a valuable biomass-derived platform molecule, which can be further catalytically converted into many industrially-relevant molecules such as γ-butyrolactone, 1,4-butanediol or tetrahydrofuran. The influence of the support nature...

For the first time ammonium perrhenate (APR) supported on zeolites of the types H-β, H-ZSM-5 and HÀ Y were shown to be efficient catalysts for the deoxydehydration (DODH). They catalyzed the transformation of 1,2-hexanediol (1,2-HDO) to 1hexene in the presence of 3-octanol as reductant and solvent with productivities up to 0.24 mol 1-hexene • g Re À 1 • h À 1 . The productivity decreased with increasing Si : Al ratio, independent of the zeolite structure. Catalyst characterization indicates Re-species to preferably bind to the Al centers of the support, resulting in a higher amount of active metal centers.

Pt–Re bimetallic catalysts have many applications, ranging from catalytic reforming to the reduction of carboxylic acid derivatives. However, the exact role of Re in these systems has remained a matter of discussion, partly due to the plethora of suggested synthesis protocols and analysis conditions. This study presents an extensive comparison of such literature protocols and the resulting materials. In detail, characterization by N2 physisorption, X-ray diffraction, temperature-programmed reduction, CO pulse chemisorption, Fourier-transform infrared spectroscopy of adsorbed CO, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and in situ X-ray photoelectron spectroscopy is combined with catalytic testing to yield synthesis–structure–activity correlations. Accordingly, the investigated catalysts share common features, such as Pt0 nanoparticles (1–4 nm) decorated with partially reduced Re species (ReO x–y ). The remaining rhenium oxide is spread over the TiO2 support and enhances Pt dispersion in sequential impregnation protocols. While differences in the number of active sites (Pt0/ReO x–y ) mostly explain catalytic results, small variations in the extent of Re reduction and site composition cause additional modulations. The optimal bimetallic catalyst outperforms Ru/C (previous benchmark) in the reduction of N-(2-hydroxyethyl)­succinimide, an important step in the production of a bio-based polyvinylpyrrolidone polymer.

Abstract:Three new zinc complexes with monoamine-guanidine hybridligands have been prepared, characterized by X-ray crystallography and NMR spectroscopy, and tested in the solvent-free ring-opening polymerization of rac-lactide. Initially the ligands were synthesized from camphoric acid to obtain TMGca and DMEGca and then reacted with zinc(II) halides to form zinc complexes. All complexes have a distorted tetrahedral coordination. They were utilized as catalysts in the solvent-free polymerization of technical rac-lactide at 150 • C. Colorless polylactide (PLA) can be produced and after 2 h conversion up to 60% was reached. Furthermore, one zinc chlorido complex was tested with different qualities of lactide (technical and recrystallized) and with/without the addition of benzyl alcohol as a co-initiator. The kinetics were monitored by in situ FT-IR or 1 H NMR spectroscopy. All kinetic measurements show first-order behavior with respect to lactide. The influence of the chiral complexes on the stereocontrol of PLA was examined. Moreover, with MALDI-ToF measurements the end-group of the obtained polymer was determined. DFT and NBO calculations give further insight into the coordination properties. All in all, these systems are robust against impurities and water in the lactide monomer and show great catalytic activity in the ROP of lactide.

The reductive transformation of biogenic carboxylic acids and ammonia presents a promising route to access pyrrolidones as N‐containing bio‐based fine chemicals. Herein, we report the first approach to convert itaconic acid to N‐unsubstituted pyrrolidones. The reaction was carried out in low amounts of water as solvent with hydrogen as reduction agent and ammonia as nitrogen source. A Ru/C catalyst was found to be highly active for this reaction. Furthermore, a coherent reaction network could be proposed. Catalyst recycling and variation of substrates demonstrate both the robustness and broad scope of the presented catalytic system.

The adsorption of biogenic hydroxymethylfurfural and fructose from aqueous phase reaction mixtures on polymer-based spherical activated carbons was studied. The adsorbents show a high capacity in combination with an outstanding selectivity due to their hydrophobic surface. Equilibrium isotherms and breakthrough curves of single and multicomponent solutions as well as the desorption behavior were measured and modelled accordingly. Overall, the results obtained enable further process development for adsorptive liquid phase separation in future biorefinery processes.

Bio-based monomers are produced in a two-step process starting from common platform chemicals. The heterogeneously catalyzed reduction of bio-based acids into 2-pyrrolidones makes for a promising drop-in technology for the industrial NVP production.