Ni-based Layered Double Hydroxides Derived Oxide And Composite Materials Catalyst For The Hydrogenation Of 5-hydroxymethylfurfural

With the rapid depletion of non-renewable petroleum-based energy reserves,increasing greenhouse gas emissions and increasing environmental pollution,rich and low-cost renewable energy sources as a promising alternative to the sustainable production of liquid fuels and chemicals,which is attracting more and more attention in scientific and industrial communities.The product,5-hydroxymethylfurfural?HMF?,derived from the inedible lignocellulosic material,is derived from the acidic hydrolysis of carbohydrates through sugar,which is considered to be one of the most promising biomass-based platform molecules for the manufacture of high value-added chemicals and biofuels.Of all the important derivatives of HMF,especially 2,5-dimethylfuran?DMF?is more promising due to its superior properties such as ideal boiling point,high energy density,and high research octane number.DMF has been identified as a highly interesting biomass-derived liquid fuel that can alternative to ethanol.Therefore,it becomes more and more important to develop an efficient catalyst for converting HMF to DMF.Layered double hydroxide?LDH?is used as a catalyst support and precursor because it has the characteristics of acidity and alkalinity,stability,and cation exchangeability.The calcined mixed metal oxide?MMO?have attracted much attention in the field of catalysis,due to high specific surface,memory effect,thermal stability and other excellent properties have attracted much attention in the field of catalysis.In recent years,LDH catalytic materials prepared from transition metals such as Co,Ni,Al have been favored by researchers.In this paper,LDH prepared by urea hydrothermal method was used as the precursor,and the hydrocatalytic effect of hydrotalcite oxide and its combination with cobalt porphyrin on the hydrogenation of DMF was studied.The details are as follows:?1?Mixed metal oxides NiCoTi-x?x=NiCo/Ti?derived from LDH for selective hydrogenation of 5-hydroxymethylfurfural.NiCoTi-LDH were synthesized by hydrothermal method and calcined to obtain the derived NiCoTi-MMO.Different catalysts were obtained by adjusting the ratio of NiCo to Ti,and uesd to research the catalytic performance on the selective hydrogenation of HMF.A series of characterization such as FT-IR,XRD,BET,SEM,TEM,XPS and TGA are employed to investigate the structure and composition of the precursors and catalyst.The uniform distribution of the three metal cations in the LDH precursor ensures a good dispersion of each metal cation in the mixed metal oxide catalyst.The effects of reaction temperature,reaction time,NiCo/Ti ratio and hydrogen pressure on catalytic performance are investigated with NiCoTi-8 catalyst as the optimum,and the possible catalytic mechanism is proposed.The repeatability test of NiCoTi-8 catalyst has been performed.The catalyst still has good catalytic performance during many uses,indicating that it has good stability.?2?NiAl-LDH cobalt porphyrins complex for selective hydrogenation of 5-hydroxymethylfurfural.In this section,NiAl-LDH was successfully prepared by hydrothermal method,and the cobalt porphyrin and NiAl-LDH are compounded by different synthetic methods to obtain CoTAPP/NiAl-LDH.The calcined Co-N-C/NiAl-MMO as the catalyst for the selective hydrogenation of HMF.In order to provide anchor point for metal particles during high temperature pyrolysis of M-C-N,the aggregation of metal ions is inhibited.In addition,cobalt porphyrin is composed of alternating nitrogen-containing ligands and Co ions,which can effectively control the dispersion of active sites at the atomic level.A series of characterization such as XRD,SEM,TEM,FT-IR,TGA,Py-IR,XPS,NH₃-TPD and CO₂-TPD are employed to investigate the structure and composition of the precursors.The effects of reaction temperature,reaction time,and hydrogen pressure on catalytic performance are investigated,and the possible catalytic mechanism is proposed.In addition,the reason for deactivation of the catalyst after repeated use is explained.