Hledat publikace

The solvent effects on hydrodeoxygenation (HDO) of 4-(2-furyl)-3-buten-2-one (F-Ac) over Pt/TiO2cat-alyst were investigated at T = 200◦C and P(H2) = 50 bar. The initial reactant is the main product of aldolcondensation between furfural and acetone, which constitutes a promising route for the production ofbio-based chemicals and fuels. A sequence of experiments was performed using a selection of polar sol-vents with different chemical natures: protic (methanol, ethanol, 1-propanol, 2-propanol, 1-pentanol)and aprotic (acetone, tetrahydrofuran (THF), n,n-dimethylformamide (DMF)). In case of protic solvents, agood correlation was found between the polarity parameters and conversion. Consequently, the highesthydrogenation rate was observed when 2-propanol was used as a solvent. In contrast, the hydrogenationactivity in presence of aprotic solvents was related rather to solvent-catalyst interactions. Thus, the ini-tial hydrogenation rate declined in order Acetone > THF > DMF, i.e. in accordance with the increase in thenucleophilic donor number and solvent desorption energy. Regarding the product distribution, a complexmixture of intermediates was obtained, owing to the successive hydrogenation (aliphatic C C, furanicC C and ketonic C O bonds), ring opening (via C O hydrogenolysis) and deoxygenation reactions. Basedon the proposed reaction scheme for the conversion of F-Ac into octane, the influence of the studiedsolvents over the cascade catalytic conversion is discussed. A significant formation of cyclic saturatedcompounds such as 2-propyl-tetrahydropyran and 2-methyl-1,6-dioxaspiro[4,4]nonane took place viaundesirable side reactions of cyclization and isomerization. The best catalytic performance was foundwhen using acetone and 2-propanol as solvents, achieving significant yields of 4-(2-tetrahydrofuryl)-butan-2-ol (28.5–40.4%) and linear alcohols (6.3–10.4%). The better performance of these solvents maybe associated with a lower activation energy barrier for key intermediate products, due to their mod-erate interaction with the reactant and the catalyst. In case of methanol and DMF, undesired reactionsbetween the reactant and the solvent took place, leading to a lower selectivity towards the targetedhydrodeoxygenated products.