Preparation Of Carbon Nitride Complex Hydrotalcite Catalyst And Its Catalytic Performance For Hydrogenation Of 5-Hydroxymethylfurfural

Dwindling fossil fuel stocks,climate change caused by anthropogenic greenhouse gas emissions and increasing environmental problems have stimulated research into the production of clean biofuels from renewable resources.Biomass energy has attracted extensive attention because of its diversity,universality,abundance and cheapness.Biomass not only stores solar energy,but can also be transformed into solid,liquid or gaseous fuels via appropriate processing.5-hydroxymethyl furfural（HMF）can be converted from biomass under acidic conditions.HMF is an important biomass-based platform compound that catalyzes conversion to high value added chemicals and fuels.Among the many derivatives of HMF,2,5-dimethylfuran（DMF）is regarded as the second generation biofuel due to its similar properties to many existing transportation fuels.Therefore,the preparation of DMF from HMF is of great significance to the chemical industry and energy sector.High temperature derived metal oxides（MMO）of hydrotalcite（LDH）have been widely used in catalysis due to their unique structure memory effect and thermal stability.The anchoring site of nitrogen-doped carbon structure can inhibit the loss and aggregation of metal particles and make the catalyst structure more stable.In this paper,nitrogen-doped carbon hydrotalcite based catalysts were prepared around non-noble metals for hydrogenation of HMF to DMF.The main work is summarized as follows:（1）Hydrogenation of HMF over modified Co Al-hydrotalcite catalyst to produce DMF.A novel mixed metal oxide catalyst CuCoNiAl-MMO containing Cu,Co,Ni and Al was prepared by hydrothermal method and applied to hydrogenolysis of HMF to DMF.The catalysts were characterized by SEM,TEM,XRD,XPS,FT-IR,H₂-TPR,etc.The effects of reaction time,reaction temperature and hydrogen pressure on HMF hydrogenation and the recycling performance of the catalyst were investigated.Under relatively mild reaction conditions（180°C,1.0 MPa H₂,6 h）,CuCoNiAl-MMO showed both a high initial activity and selectivity for hydrogenolysis of HMF to DMF,with HMF conversion rate of 99.8%and DMF selectivity of 95.3%.（2）Efficient and selective hydrogenation of HMF to DMF over a non-noble Co NC_x/NiFeO catalyst.A Co NC_x/NiFeO catalyst was synthesized by combining cobalt phthalocyanine（Co Pc）with Ni Fe-LDH by ultrasonic exfoliation.The catalysts were characterized by SEM,TEM,XRD,XPS,FT-IR,H₂-TPR,etc.The effects of reaction time,reaction temperature and hydrogen pressure on HMF hydrogenation and the recycling performance of the catalyst were investigated.Co NC_x/NiFeO showed very high initial activity and selectivity for the hydrogenation of HMF to DMF in tetrahydrofuran（THF）under mild reaction conditions（180°C,1.0 MPa H₂,6 h）,evidenced by a 99.8%HMF conversion and 94.3%DMF selectivity.（3）Nitrogen-doped carbon modified Cu-Co catalyst for efficient transfer hydrogenolysis of HMF to DMF.The CN_x-Cu Co Al-MMO catalyst was prepared by a one-pot hydrothermal method using melamine as the NC precursor.The catalysts were characterized by SEM,TEM,XRD,XPS,FT-IR,H₂-TPR,etc.The effects of reaction time,reaction temperature and hydrogen pressure on HMF hydrogenation and the recycling performance of the catalyst were investigated.Under the reaction conditions of 200°C and 1.0 MPa H₂,99.9%HMF conversion and DMF selectivity can be obtained for 3 h.The catalyst showed good stability.