ABSTRACT
The sequential transfer hydrogenation/hydrogenolysis of furfural and 5-hydroxymethylfurfural to 2-methylfuran and 2,5-dimethylfuran was studied over in situ reduced, Fe2 O3 -supported Cu, Ni, and Pd catalysts, with 2-propanol as hydrogen donor. The remarkable activity of Pd/Fe2 O3 in both transfer hydrogenation/hydrogenolysis is attributed to a strong metal-support interaction. Selectivity towards hydrogenation, hydrogenolysis, decarbonylation, and ring-hydrogenation products is shown to strongly depend on the Pd loading. A significant enhancement in yield to 62%, of 2-methylfuran and 2-methyltetrahydrofuran was observed under continuous flow conditions.
Subject(s)
Furans/chemistry , Hydrogen/chemistry , Alcohols/chemistry , Catalysis , Copper/chemistry , Ferric Compounds/chemistry , Hydrogenation , Nickel/chemistry , Palladium/chemistryABSTRACT
The selective oxidation of alcohols is a pivotal transformation within industrial and synthetic chemistry. In this contribution we use O2 as terminal oxidant and (H)NO(x) species as oxygen shuttle in order to mediate the oxidation of primary and secondary alcohols under the influence of a solid acid catalyst. Process optimization and intensification through the use of a continuous three-phase flow reactor is demonstrated. Space-time yields were found to increase by two orders of magnitude with respect to batch experiments, along with additional gains in selectivity and a decrease of N2O formation.
Subject(s)
Alcohols/chemistry , Aerobiosis , Kinetics , Oxidation-Reduction , TemperatureABSTRACT
The dehydration of D-fructose to 5-hydroxymethylfurfural was studied under single-phase conditions in the low boiling solvent 1,4-dioxane at moderate temperatures in the presence of the solid acid-catalyst Amberlyst-15. The reaction was first examined and optimized under batch conditions, where it was found that the yield could be increased up to 75 % by adding small amounts of DMSO. Subsequently, the reaction was performed under continuous flow in a fixed bed reactor. Internal and external mass transfer limitations could be eliminated by changing the particle size and by adjusting the flow rate. Under continuous conditions, the HMF yield could be further increased to 92 %; the space-time yield was found to be 75 times higher compared to the batch case. A long-term stability test (96â h), including solvent regeneration, demonstrated that the catalyst is stable over time. Additionally, it was shown that even small amounts of water have a negative effect on the HMF yield. Overall, the present system shows a good alternative to other systems presented in literature because high space-time yields and selectivities were obtained under relatively mild and continuous conditions.
Subject(s)
Fructose/chemistry , Furaldehyde/analogs & derivatives , Dioxanes/chemistry , Furaldehyde/chemistry , Green Chemistry Technology , Styrenes/chemistry , Water/chemistryABSTRACT
Functionalizing organic molecules is an important value-creating step throughout the entire chemical value-chain. Oxyfunctionalization of e.g. C-H or C=C bonds is one of the most important functionalization technologies used industrially. The major challenge in this field is the prevention of side reactions and/or the consecutive over-oxidation of the desired products. Despite its importance, a fundamental understanding of the intrinsic chemistry, and the subsequent design of a tailored engineering environment, is often missing. Industrial oxidation processes are indeed to a large extent based on empirical know-how. In this mini-review, we summarize some of our previous work to help to bridge this knowledge gap and elaborate on our ongoing research.
