Study On The Construction Of Ni-Cu Catalysts Derived From Layered Double Hydroxide And The Promotion To Hydrogenation Of γ-Valerolactone To 2-Methyltetrahydrofuran

To promote sustainable development,China put forward the goal of carbon peak and neutrality in 2020.As one of the most abundant renewable resources in the world,biomass waste has the characteristics of wide distribution,low cost and carbon neutrality,and it shows great potential to replace traditional fossil fuels.2-methyltetrahydrofuran（2-MTHF）is a promising biofuel and gasoline additive,as well as one of the most attractive downstream products of the biomass-based platform compoundγ-valerolactone（GVL）.Due to the high thermal stability of GVL,it is quite technically difficult to achieve highly selective conversion of GVL to downstream materials.In order to improve the low activity and selectivity of cheap transition metal catalysts in the synthesis of 2-MTHF from GVL,it is of great practical significance to develop high-performance heterogeneous catalysts for this process.Layered double hydroxide（LDHs）has the characteristics of changeable metal composition,adjustable acid-base and thermal stability,which create more possibilities for the preparation of catalytic materials with excellent properties.Previous studies have shown that cheap Cu-based catalysts showed great potential in improving the conversion of GVL.On this account,in this work,a series of mono/bimetallic supported catalysts Ni_xCu_3-x/Al₂O₃（x=0,1,1.5,2,3）and mixed metal oxides（Ni₁Cu₂Al-MMO-T）derived from LDH precursors were prepared and evaluated for the hydrogenation of biomass-derived GVL to 2-MTHF.Compared with the catalysts prepared by traditional impregnation method,the optimal bimetallic catalyst Ni₂Cu₁/Al₂O₃ showed high selectivity to 2-MTHF（88.1%）with complete conversion of GVL under 200°C,5 MPa H₂ pressure after 5 h.Detailed characterization analyses revealed the existence of appropriate acid sites and Ni-Cu alloy in bimetallic catalysts,which was responsible for the promotion of selectivity to target product.More importantly,the strong interaction between Ni and Cu changed the chemical environmental of the Cu species on the catalysts surface which generated different copper species and enhanced its H₂ activation ability.Considering that there is a large proportion of metal oxidation state on the surface of the prepared bimetallic catalysts,this work simplified the preparation procedure of the catalysts and tried to use the mixed metal oxide derived from LDHs directly as a catalyst to promote the hydrogenation conversion of GVL.Under the same reaction conditions,GVL was completely converted and the selectivity to2-MTHF was 86.9%.The analysis showed that the synergistic effect of Cu⁺and acid-base sites promoted the hydrogenation process.In addition,the reusability of two catalysts and the impact of reaction conditions（such as temperature,H₂ pressure,solvents,etc.）were also discussed.