Catalytic transformation of HMF to valeric biofuels

Considering the depletion of fossil fuels resources, the corresponding increasing of oil prices and the global warming issues associated with greenhouse gases emissions, the need to move from con-ventional fossil feedstock to CO2 neutral ones for the production of fuels and chemicals is always more pressing. Biomass is an abundant, low cost and carbon-neutral renewable energy resource and on its upgrading is based the biorefinery concept. Amongst the various platform molecules, hy-droxymethyl furfural (HMF), the main product in the acid-catalyzed conversion of ligno-cellulosic biomass, has attracted a lot of interest as platform molecule because it can be converted in mono-mers for polymers, valuable intermediates for fine chemicals and above all in biodiesel components, so-called “furanics”. In a our previous study we have demonstrated that by tuning the acidity of the mesoporous catalysts surface, e.g. introducing Lewis or Brönsted acidic sites, the etherification reaction of 5-HMF with ethanol is selective to 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), a valuable biodiesel components, belonging to the class of furanics, or to ethyl 4-oxopentanoate (EOP) a potential precursor of valeric esters. The potential of valeric esters as biofuels additive is evidenced by researchers of Shell Global Solu-tion. Valeric biofuels are obtained from levulinic acid, converted to gamma-valerolactone, which is hydrogenated to valeric acid and then esterified to produce valerate esters. Depending on the reactants used in the esterification, valeric biofuels may be in the form of biogasoline or biodiesel, and can be well mixed with other fuels currently available. Reducing the steps in the production of valeric esters will be desiderable. In this work we propone an alternative way to have valeric biofuels by direct reaction of HMF with ethanol to give EOP and subsequent selective hydrogenolysis of carbonyl in γ position of EOP to the corresponding valerate ester.