A Study On Nickel Phyllosilicate Catalyst For The Selective Hydrogenation Of 5-Hydroxymethylfurfural

Biomass is the most abundant renewable resource in nature,and its development and utilization are considered as a new way to replace fossil resources to meet the needs of human energy and production materials.5-Hydroxymethylfurfural(5-HMF)is an important biomass platform compound,which can be converted into a variety of high value-added chemicals.For example,2,5-Hydrofuranediol(2,5-FDM)and 2,5-Tetrahydrofuranediol(2,5-THFDM)is expected to replace 1,4-Cyclohexanediol(1,4-CHDM)as a polyester monomer or polymer solvent.5-HMF contains aromatic furan ring,which has stable chemical properties.Hydrogenation process is generally under noble metal catalytic system or high temperature and pressure conditions.However,C-0 bond outside the furan ring is easy to break and dehydroxylate.Therefore,it is of great significance to study selective activation of 5-HMF C-0 bond under mild conditions and develop a high active non-noble metal based catalyst.Nickel-based catalysts are commonly used in 5-HMF selective hydrogenation,because of their low price and high activity.However,the active nickel species are easy to lose and sinter in liquid phase.Not only that,organic matter produced by reactions is easy to accumulate on these catalysts,leading to deactivation.Therefore,the preparation of nickel-based catalysts with stable structure is of great significance.It is found that metal phyllosilicate catalysts can stabilize metal nanoparticles and make them hard to lose.Acid sites on the surface also play a synergistic role and improve the hydrogenation rate.This provides an idea for designing stable and efficient nickel-based catalysts.In this paper,by in-situ precipitation of layered nickel phyllosilicate as precursor,nickel-based catalysts with stable structure and uniform particle size distribution are prepared for selective hydrogenation of 5-HMF.Nickel-based catalysts prepared by traditional impregnation,sol-gel and deposition-precipitation methods are compared to investigate the selective hydrogenation performance of 5-HMF.The physical and chemical properties of nickel phyllosilicate catalyst are studied by a series of characterization methods.The results show that compared with traditional nickel catalysts,nickel phyllosilicate catalyst prepared by ammonia evaporation and hydrothermal process exhibits excellent 5-HMF selective hydrogenation performance.Compared with different morphologies of nickel phyllosilicate,lamellar nickel phyllosilicate catalyst(Ni-PS-L)has higher 5-HMF hydrogenation activity.100%conversion of 5-HMF and 90.4%selectivity of 2,5-THFDM can be obtained under reaction conditions(373 K,8 h,1.5 MPa H2).Moreover,Ni-PS-L maintains a stable 5-HMF conversion and 2,5-THFDM selectivity after 7 times of cycle reaction.Nickel phyllosilicate structure can stabilize the nickel nanoparticles,thus preventing particle aggregation and metal loss.As Lewis acid site,coordination unsaturated nickel divalent on surface promots the adsorption of electron-rich substrate,which is beneficial to 5-HMF saturation under mild conditions.The surface Lewis acid density of the catalyst can be controlled by changing precursor treatment conditions,so that C-O bonds in the product molecules can be selectively activated.Large specific surface area and loose pore structure are favorable for the desorption of organic matter from the active center,leading to good cyclic stability of catalysts.These four characteristics make nickel phyllosilicate catalysts of great potential in the application of biomass hydrogenation.