| Owing to the increasing exploitation and use of non-renewable fossil fuels,the problems of energy shortage and environmental pollution are becoming a global concern.So developing renewable energy is the world's top priority.Biomass,as a renewable green energy source,is the ideal substitute for fossil fuels.In order to meet the demand of social development,fabrication of bio-fuels and high value-added chemicals from renewable biomass and biomass-derivatives by thermal catalysis reaction has aroused great research attention.In contrast to fossil fuels,biomass contains more oxygen.Therefore,the preparation of high value-added oxygen-containing compounds from biomass or biomass-based platform molecules is an irreplaceable development direction of energy and chemical industry in the future.The selectively catalytic hydrodeoxygenation process is one of the most effective methods for conversion of biomass-based platform molecules,like furfural,into corresponding bio-fuels and high value-added chemicals.And the realization of the process is highly dependent on the design and preparation of catalysts with high activity,selectivity and stability.To address some issues existed in current catalytic process,such as the complex catalyst preparation process,poor activity of catalysts,high price of noble metal and harsh reaction conditions,etc.,we aimed at developing a variety of simple,green and effective methods to synthesize high efficient carbon-based non-noble metal catalysts for the selectively catalytic hydrogenation or transfer hydrogenation of unsaturated compounds under relatively mild reaction conditions.The relationship between the composition and structure of catalyst and its high activity is revealed,and the main results are summarized as follows:1.The main reason for the poor catalytic activity of carbon materials is the lack of active sites on the surface.So the surface modification of carbon materials,such as sulfonation,is well worth studying.In this work,the non-noble metal catalysts supported by sulfonate group grafted active carbon(Cu/AC-SO3H,Ni/AC-SO3H)were prepared and activated simultaneously by liquid phase chemical reduction method.Specifically,the Cu/AC-SO3H catalyst has small average particle size(6.5 nm),high Cu dispersion(15.5%)and high surface area(826 m2/g).The catalyst displayed an enhanced catalytic performance for hydrogenation of furfural to furfuryl alcohol,in which almost 100%furfuryl alcohol was obtained.Cycling test proved the prepared catalyst could be recycled and reused for several times without noticeably reduced catalytic activity of hydrogenation.Similarly,the average particle size and Ni dispersion of the prepared Ni/AC-SO3H were 7.7 nm and 13.17%,respectively.Under the mild reaction conditions,it showed excellent furfural hydrogenation and transfer hydrogenation performance,in which furfuryl alcohol and tetrahydrofurfuryl alcohol were selectively obtained,respectively,and could be reused five times without loss in activity.2.The preparation of traditional metallic catalysts requires high temperature calcination and H2 reduction,which inevitably leads to the increase of particle size and the agglomeration of particles.This work innovatively utilizes active carbon as the reducing reagent to achieve highly dispersed non-noble metal catalysts(Cu/AC,Co/AC)by simply controlling the calcination conditions.The average particle size and Cu dispersion of the prepared Cu/AC were 14.9 nm and 6.7%,respectively.An almost 100%yield of 2-methylfuran can be obtained within 4 h under 170 C reaction temperature and 3 MPa H2 pressure in the hydrogenation of furfural.Cycling test proved the synthesized catalyst could be reutilized during successive catalytic cycles.For the identical catalyst,in the transfer hydrogenation of furfural and levulinic acid,91.6%2-methylfuran selectivity and 89.9%y-valerolactone selectivity were also attained,respectively.For the prepared Co/AC catalyst,similarly,the average particle size,the surface area and pore volume were 6.2 nm,774.1 m2/g and 0.311 cm3/g,respectively,and it is beneficial to the dispersion of active metal particles.The as-synthesized Co/AC-500 catalyst was used as heterogeneous catalyst for the selective transfer hydrogenation of various ?,?-unsaturated aldehydes using 2-propanol as hydrogen donor.Consequently,a range of substrates were selectively hydrogenated at the C=O bond with>90%selectivity at full conversion.3.N-doped carbon supported metal catalysts have been widely investigated for catalytic hydrogenation reactions,demonstrating superior catalytic activity and selectivity owing to N doping effectively tuning the electronic structure and surface property of carbon supports to promote the catalytic performance.In this work,N-doped activated carbon supported metallic nickle catalyst(Ni/NAC-1-1073)was fabricated by two-step calcination method in N2 atmosphere.And the average particle size,N doping content and surface area of the prepared Ni/NAC-1-1073 were 13.1 nm,3.65 at.%and 561.2 m2/g,respectively.Under optimized conditions,the Ni/NAC-1-1073 demonstrated complete conversion and almost 100%tetrahydrofurfuryl alcohol selectivity for the direct hydrogenation of furfural,and could be reused several times without any loss in activity.More importantly,in the transfer hydrogenation of furfural to furfuryl alcohol,amolst 100%furfural conversion was also obtained.4.The three-dimensional porous carbon is often used as a catalyst or catalyst carrier because of its large specific surface area,high porosity,superior conductivity and relative chemical inertia.Herein,we report a facile and scalable pyrolysis strategy for the synthesis of Cu-Co based bimetallic catalyst(denoted as CuCo0.8@C-500)using glucose as the carbon source.The Cu-Co based bimetallic nanoparticles were uniformly coated in three-dimensional porous carbon,and the average particle size was 13.5 nm.This catalyst can efficiently transform furfural to cyclopentanone in an aqueous medium under mild condition,and 90.2%yield of CPO was attained at 150?,0.5 MPa H2 pressure and 9 h,can be reused for several times without loss of activity.5.As a catalyst or catalyst support,N-doped carbon nanotubes have been widely used in the field of catalysis owing to their improved mass transfer ability and superior stability.First,a facile one-pot pyrolysis approach using melamine as carbon and nitrogen source was developed to fabricate metal nanoparticles embedded in bamboo-like N-doped carbon nanotubes(named as Co@NCNTs-600-800/Ni@NCNTs-600-800).Among them,the average diameter of carbon nanotubes of the Co@NCNTs-600-800 catalyst is 40-60 nm,the wall thickness is 2-4 nm,and the Co content is 40.3 wt%.The optimized catalyst exhibited outstanding furfural hydrogenation activity in aqueous media.The high yields of furfuryl alcohol(100%)and cyclopentanone(75.3%)were achieved at 80 ? and 140 ?,respectively.In addition,the as-prepared Ni@NCNTs-600-800 catalyst also exhibited remarkable activity in furfural hydrogenation process.Under the optimal conditions,a maximum tetrahydrofurfuryl alcohol yield(99.5%)was obtained.Second,a supported cobalt catalyst in N-doped carbon nanotubes(named Co-440-900)is successfully fabricated using MOF as the precursor via two-step pyrolysis method.And the average particle size and surface area of the prepared Co-440-900 were 10 nm and 157 m2 g-1,respectively.This sample showed excellent catalytic activity,perfect chemoselectivity and high catalytic stability for a wide range of bio-derived unsaturated compounds and substituted nitroarenes at low temperature. |
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