Executive Summary : | 2-pyrone molecules are the versatile class of platform chemicals that are produced from the fermentation of waste lignocellulosic biomass. Upon undergoing ring-opening (RO) and decarboxylation reaction in the presence of water or Brønsted acid catalysts such as SiO₂/Al₂O₃ 2-pyrones have been upgraded to a variety of value added fuels and chemicals at low temperature and pressure conditions. For example, Dumesic et al. employed triacetic acid lactone (TAL), a 2-pyrone molecule as a feed stock to produce acetylacetone via RO and decarboxylation reaction in the presence of water. Similarly, 6-amyl-alpha pyrone (6PP) another class of 2-pyrone molecule underwent RO and decarboxylation reaction to produce 4-nonanone. Furthermore, partially saturated 2-pyrone have been shown to undergo RO and decarboxylation reaction via retro-Diels Alder (rDA) reaction mechanism. On the other hand, in the presence of a noble metal catalyst such as Pd/C both TAL and 6PP underwent complete hydrogenation to produce ring saturated products such as 6-methyl-5,6-dihydro-2-pyrone3 and δ-decalactone without undergoing RO and deoxygenation reaction. In contrast highly reducible noble metals such as Pd, Pt, Rh etc. when combined with oxophilic promoters (Re, Mo etc.) have been observed to exhibit high activity in the hydrodeoxygenation reactions of phenolics, biomass derived polyols etc. For instance, Dumesic et al. employed a bifunctional (RhReOx/C) catalyst for the hydrogenolysis of secondary C-O bonds in biomass derived cyclic ethers. They observed that the bifunctional catalyst containing a combination of highly reducible metal (Rh) with an oxophilic promoter (Re) promotes C-O bond hydrogenolysis to produce terminal diols from cyclic ethers. In this proposal, we propose to use a similar bifunctional catalyst consisting of cheap and easily available reducing metal such as Ni in combination with an oxophilic promoter (Re, W, Co, Fe etc.) to produce polymer precursors or fuel additives from biomass derived 2-pyrone molecules. It is hypothesized that Ni present in the bifunctional catalyst will catalyze the hydrogenation reaction whereas the oxophilic promoter will lead to RO and deoxygenation of the 2-pyrones to produce either diols or alkanes. An array of catalyst materials will be screened computationally using quantum mechanical density functional theory (DFT) calculations combined with ab-inito microkinetic modelling (MKM). Selected Ni based bifunctional catalysts showing high reactivity will be tested experimentally for the RO and deoxygenation reaction of 2-pyrone molecule with an aim to produce polymer precursors or fuel additives from biomass. |