Anders Theilgaard Madsen

Oxidation of glycerol and propanediols in methanol over heterogeneous gold catalysts

Aerobic oxidation of glycerol over metal oxide supported gold nanoparticles in methanol results in the formation of dimethyl mesoxalate in selectivities up to 89% at full conversion. The oxidative esterification takes place in methanol, acting both as solvent and reactant, and in the presence of base. Thus, it constitutes a direct transformation of the glycerol by-product phase from biodiesel production or from glycerol obtained e.g. by fermentation. Au/TiO2 and Au/Fe2O3 was found to have similar catalytic activity, whereas Au/C was inactive. 1,2-Propanediol was oxidized to methyl lactate with a selectivity of 72% at full conversion, while 1,3-propanediol yielded methyl 3-hydroxypropionate with 90% selectivity at 94% conversion. Methyl 3-hydroxy propionate can be easily converted into methyl acrylate, which is then a green polymer building block.

Challenges and perspectives for catalysis in production of diesel from biomass

The production of biofuels is expected to increase in the future due to environmental concerns, accelerating oil prices and the desire to achieve independence from mineral oil sources. Of the proposed methods for diesel production from biomass, the esterification and transesterification of plant oils or waste fats with methanol is the most prominent and has been applied industrially for a decade. Homogeneous acid and base catalysis is normally used, but solid acids, solid bases, ionic liquids and lipases are being developed as replacements. Hydrodeoxygenation of vegetable oils has likewise been commercialized. Diesel from biomass may also be produced by catalytic upgrading of bio-oils from flash pyrolysis, by aqueous-phase reforming of carbohydrates into non- or mono-functionalized hydrocarbons via consecutive reduction-condensation reactions, or by gasification of biomass to synthesis gas of CO and H2 and liquefaction to alkanes via Fischer–Tropsch synthesis. Here, the current challenges and perspectives regarding catalysis and raw materials for diesel production from biomass are surveyed.