Construction Of Hafnium-based Acid-base Functional Materials And Their Catalytic One-pot Cascade Conversion Of Furfural To γ-valerolacton

With the increasing demand for fine chemicals and fuels in modern society,the excessive exploitation and consumption of nonrenewable fossil energy resources are getting worse.There was thus an urgent need to seek renewable energy substitutes.Biomass was the most abundant organic carbon source and was widely distributed,which make it often used to produce biofuels and various valuable chemicals.γ-Valerolactone（GVL）was an attractive biomass-derived platform molecule that plays an important role in the production of biofuels and biopolymers.Here,a catalytic system of hafnium-based acid-base functional material was developed.One-pot cascade conversion of biomass-based derivative furfural（FF）to GVL,including hydrogenation,hydrolysis ring-opening,partial hydrogenation,cyclization,and other steps（e.g.,etherification,esterification,and lactonization）.This catalytic strategy opened a new avenue for the selective conversion of biomass feedstocks involving multiple steps and complex processes.The specific research contents are as follows:（1）A Hf Cl₄-mediated acid–base bifunctional catalytic system was developed,which could effectively upgrade FF to GVL in one pot.The yield of GVL could reach64.2%at 180℃in 8 h.It was found that the Lewis acid（Hf Cl₄）and the in situformed Lewis base species Hf O（OH）₂·x H₂O in medium strength were conducive to promoting FF and isopropyl levulinate（IPL）to undergo the CTH process,while the strong Br?nsted acid（HCl）generated by Hf Cl₄ hydrolysis made the furan ring open easily.The reaction system was optimized by response surface methodology.Kinetic analysis showed that the transfer hydrogenation of FF-FA and EL-GVL was the key step in the whole conversion process.Finally,the used catalyst could better catalyze the transfer hydrogenation of FF to FA after calcination.（2）The biomass-derived phytic acid（Ph A）was used as an organic ligand to coordinate with Hf Cl₄ by a simple hydrothermal method to obtain Hf-Ph A with different proportions.Hf-Ph A（2.5:1）exhibits excellent catalytic activity for the two key transfer hydrogenation steps（FF-FA and EL-GVL）of FF one-pot cascade conversion to GVL（reaction at 120℃for 2.5 h,FA yield was 96.1%;the yield of GVL was 92.2%at 180℃for 3 h）.This was mainly due to the appropriate acid-base content（3.7 vs 1.8mmol/g）,high specific surface area（95.4 m²/g）and pore volume（0.19 cm³/g）.The catalyst was good reusability,and its catalytic activity was not significantly reduced after five times of use.（3）The safer and more stable biomass derivative glucose was used as a raw material,which was carbonized and coordinated with Hf Cl₄ by a simple solvothermal method,and the strength of the Br?nsted acid was enhanced by grinding-SO₃H.he reaction system was optimized by single factor and response surface method（isopropanol as hydrogen donor,reaction at 180℃for 8 h,GVL yield up to 71.3%）.The characterization results showed that GPCS-Hf（1:1.5）had strong Lewis acidity basicity,B?nsted acidity and good porosity（the specific surface area of 181.6 m²/g and the pore volume is 0.34 cm³/g）,which were the main reasons for its excellent activity.A possible reaction mechanism was proposed based on characterization discussion and data analysis.GPCS-Hf（1:1.5）showed good reusability in the reaction system of FF-GVL,and its activity did not decrease significantly after five cycles.