Catalytic Hydrogenation Of Levulinic Acid To Produce ?-valerolactone And 2-methyltetrahydrofuran

Renewable biomass is considered as a promising renewable alternative to fossil fuels,because it can be transformed into a wide range of value-added chemicals,clean solvents,and high-energy density fuels.y-Valerolactone(GVL)can be applied as gasoline blend,green solvent,food additive,precursor in perfume production and precursors to a variety of monomers.It can be transformed to liquid alkenes used for transportation fuels.2Methyltetrahydrofuran(2-MTHF)can be applied as biofuel,gasoline blend,green solvent and intermediate of pharmaceutical synthesis.Compared with y-valerolactone,2methyltetrahydrofuran can be straightforward used in nowadays gasoline facilities and engines.It is of great significance to produce y-valerolactone and 2methyltetrahydrofuran by the hydrogenation of levulinic acid(LA),a biomass-derived platform molecule.Cu/ZrO2-dp catalysts with abundant Cu-ZrO2 interfaces were elaborately fabricated by depositing amorphous ZrO2 onto Cu NPs for the hydrogenation of LA to GVL.Via the created abundant Cu-ZrO2 interfaces,the optimal 3Cu/ZrO2-dp catalyst revealed excellent catalytic property at mild reaction conditions and obtained the highest GVL mass productivity of 266.0 mmol GVL·h-1·g-1 Cu,which was 12.5 and 2.3 times than Cu/ZrO2 catalysts with equivalent Cu loadings prepared by traditional impregnation(3Cu/ZrO2-im)or co-precipitation(3Cu/ZrO2-cp).To our knowledge,this GVL mass productivity precedes those acquired by non-noble metal catalysts under similar reaction conditions in previous reports.Via multifarious systemic characterizations,density functional theory(DFT)calculations,and kinetic studies,it was found that interfacial active centers were created at Cu-ZrO2 interfaces,which contained oxygen vacancies(Ov),negatively charged Cu?-and partially reduced Zr3+.The Ov benefitted the adsorption and activation of LA by its ketone group and negatively charged Cu?-can enhance heterolysis of H2,which leaded to the formation of H+-Cu?-and Zr3+-H-active species by hydrogen spillover.Meanwhile,abundant acid sites,which derived from coordinatively unsaturated and defective Zr species,were generated at Cu-ZrO2 interfaces.Via the cooperation of interfacial active centers(Cu?--Ov-Zr3+)and acid sites,the fabricated 3Cu/ZrO2-dp with abundant Cu-ZrO2 interfaces obtained exceptional catalytic property for the hydrogenation of LA to GVL.Among 2:1 nickel phyllosilicate(NiSi-PS),nickel phyllosilicate with no hydrothermal process(NiSi-PSL-pre)and 1:1 nickel phyllosilicate(NiSi-PSL)catalysts,which were prepared by an ammonia evaporation procedure,NiSi-PSL had the highest activity for the hydrogenation of ?-valerolactone.NiSi-PSL achieved 73.9%conversion of y-valerolactone and 91.9%selectivity of 2-methyltetrahydrofuran after reaction for 5 h at the condition of 220?,5 MPa H2 and 2-butanol as solvent.By analysis with the characterizations of BET,XRD,TEM-EDX,H2-TPR and NH3-TPD,it was found that the catalytic performance of nickel phyllosilicate catalysts was negatively correlated with the relative acidity of the catalysts.The weaker the relative acidity of the catalysts,the better the catalytic performance of nickel phyllosilicate catalysts.NiSi-PSL possessed good stability during the recycle test for the hydrogenation of y-valerolactone to 2methyltetrahydrofuran.The hydrogenation of y-valerolactone to 2-methyltetrahydrofuran is the rate-determining step of the hydrogenation of levulinic acid to 2methyltetrahydrofuran.When the breakthrough of ?-valerolactone activation transformation was achieved,the direct hydrodeoxygenation of levulinic acid to 2methyltetrahydrofuran would achieve conveniently.NiSi-PSL achieved 100%conversion of levulinic acid and 62%selectivity of 2-methyltetrahydrofuran after reaction for 5 h at the condition of 220?,5 MPa H2 and 2-butanol as solvent.