Catalytic Conversion Of Furfural Over Hafnium-Tannic Acid Catalyst And Analysis Of Its Structure-activity Relationship

In recent years,with the gradual depletion of fossil resources,the search for renewable resources is hot topic.A promising approach for biomass is regarded as an excellent substitute has been to produce various chemicals.Furfural is an essential biobased platform molecule.Furfural has recently been produced as one of the top value-added chemicals derived from biomass.Catalytic conversion is an effective way for the molecular transformation utilization of biomass and biomass platform,and the efficient catalyst is the key to biomass catalytic transformation utilization.In this paper,according to the characteristics of many hydroxyls’ functional groups,the natural functional molecule is characterized by a large number of hydroxyl functional groups,and the coordination of hydroxy functional groups and metal ion Hf4 + is proposed,and the tannic acid and metallic hafnium construction,hafnium—tannic acid(Hf—TA)catalyst.A process for preparing a route and used for biomass platform molecular furfural hydrogenation;in the study,the prepared catalyst not only catalyzes furfural hydrogenation,but also has catalytic activity on aldol condensation reaction,so the next study catalytic properties of Hf—TA catalyst on furfural-acetone condensation reaction.Finally,a phenolic acid containing a phenolic hydroxyl group and an aromatic acid containing a carboxyl group as model ligands,the effect of catalytic hydrogenation and condensation reaction were analyzed in depth.The main research work and the results of this paper are as follows:(1)The catalyst was prepared by solvent thermal method and prepared for furfural hydrogenation and preparation.The catalyst preparation conditions,reaction conditions,circulatory and heterogeneity were investigated,and the catalyst structure was characterized.The results show that the Hf—TA catalyst prepared by tanning acid is composed of irregular particles,with a non-fixed crystalline form structure;the transformation of furfural has good catalytic activity,in optimizing reaction conditions(substrate dosage,solvent volume,amount of catalyst,reaction temperature of 70 ℃,reaction time 3 h)can reach 94% or more conversion and yields.After 10 reuses of the catalyst,the catalyst properties were substantially unchanged,and the catalyst structure after recycling was substantially stable.Base expansion experiments show that the prepared catalyst exhibits excellent catalytic performance to different structural carbonyl compounds,indicating that the catalyst has a wide range of substrate applicability.(2)During the above study,it had a predominantly basic character that led to the production of furfural and acetone,and thus resulted in a lower selectivity to reaction by-product,indicating that the Hf—TA catalyst had a certain catalytic activity against furfural-acetone condensation.Therefore,it has been studied of catalytic furfural-acetone condensation reaction.The results show that by optimizing catalyst preparation conditions and reaction conditions,furfural: acetone molar ratio of 1:50,catalyst is 50 mg,the furfural conversion can reach more than 90% under relatively moderate conditions(80 ℃,10 h).The yield of condensation product reached 85%.The above two parts have shown that Hf—TA catalysts are not only highly active on furfural hydrogenation,but also have catalytic performance to aldol condensation.(3)In order to reveal the relationship between the Hf—TA catalyst,the phenolic substances containing phenol hydroxyl and aromatic acids containing phenyl were selected as analog ligands,and the catalytic properties of the hydration and aldol condensation reaction of the prepared catalysts were investigated.The number and type of official groups on the benzene ring in the organic ligand have a major influence on the catalytic hydrogenation reaction and the condensation reaction performance,and the catalyst catalytic hydrogenation or aldol condensation activity can be regulated by changing the type of acidic function group in the ligand.The Hf—hydroxy phenol catalyst catalytic furfural hydrogen activity is better,Hf—gallic acid(3,4,5-trihydroxybenzoic acid)catalyst had a good catalytic activity for the condensation of furfural and acetone.Catalyst structure analysis showed that the specific surface area,the acid-base site,and the acidic site of Br(?)nsted acid and the Lewis acidity ratio(B/L)coincide with the catalyst activity.The content of the catalyst of the catalyst is more significant,and the B/L ratio in acidic sites is advantageous for increasing the catalytic performance of catalyst catalytic furfural hydrogenation and aldol condensation reaction.The above results show that the route of acidic functional groups and metal hafnium ion coordination using tannic acid is feasible,and the constructed catalyst has a good catalytic performance of furfural hydrogenation and aldol condensation.The structural relationship analysis showed that the performance of the catalyst catalytic furfural hydrogenation and aldol condensation reaction can be regulated by controlling the type of functional group and preparation conditions in the ligand.This work provides basic data and technical reference for high-value catalysts in a tannic acid resource.