Synthesis And Catalytic Performance Of W-Ta Solid Acid

In recent years,fossil resources are gradually exhausted with the economic growth of all countries in the world.Energy has become the main factor restricting China's economic development,and energy transformation has become an inevitable trend.Biomass sugar,as a renewable resource,has huge reserves and is easily obtained from nature.The development and utilization of biomass resources and their conversion into energy products and bio-based chemicals can effectively alleviate environmental problems such as the shortage of fossil resources and the greenhouse effect.5-Hydroxymethylfurfural(5-HMF)and furfural(FA)are bio-based platform compounds with high added value,obtained by dehydration of biomass monosaccharides(hexa-carbon and penta-carbon sugars),and widely used in production of rubber,resin,coating,medicine,pesticide and other industries.Therefore,it is of great significance for conversion of Biomass into 5-HMF and furfural in a clean way.Tantalum solid acid has excellent catalytic activity and stability in water-containing system,and is an important catalytic material.WO₃ has a good promotion effect on many reactions.Therefore,WO₃supported on Ta₂O₅was synthesized in this paper,and various factors affecting catalyst performance were considered to determine the optimal conditions for W-Ta catalyst to catalyze conversion of biomass sugar into 5-HMF and furfural.In order to realize the high-value utilization of 5-HMF and furfural and its ecological and environmental benefits,W-Ta catalysts with different tungsten content were prepared by impregnation method.XRD,SEM,pyridine infrared and BET were used to characterize the morphology and acid sites of the catalyst.When fructose,glucose,inulin,soluble starch and xylose as reactants,5-HMF and furfural were prepared by biomass sugar dehydration using W-Ta catalyst in a two-phase water-2-butanol system.The effects of catalyst composition on the properties of catalyst and the preparation of 5-HMF and furfural from biomass sugar dehydration were investigated.The optimal conditions for preparing 5-HMF and furfural from biomass sugar as catalyzed by W-Ta catalyst were further studied.The characterization results of W-Ta catalyst showed that with the decrease of tungsten content,the acid content and acid strength of the catalyst increased.The W-Ta catalyst and Ta₁₀catalyst were used to catalyze the conversion of biomass sugar respectively.The experimental results showed that the yields of 5-HMF and furfural increased with the decrease of the tungsten content.The catalytic activity of Ta₁₀ catalyst was higher than that of Ta₉W₁,Ta₈W₂ and Ta₇W₃solid acid catalysts.The single factor variable method was used to optimize the reaction conditions,including catalyst composition proportion,catalyst dosage,reaction temperature and other aspects.The optimal reaction conditions for preparing 5-HMF were as follows:reaction at 180^?,1200mg fructose was catalyzed by 100mg Ta₁₀-360 catalyst.Under the optimal conditions,the yield of5-HMF reached 62.86%.The optimal reaction conditions for the preparation of furfural were as follows:reaction at 190 ^?,catalyzed by 1000mg xylose with 100mg Ta₁₀-360^? catalyst;Under the optimal conditions,the furfural yield reached 58.30%.After 5 times of recycling,the activity of Ta₁₀catalyst was basically stable,and the yield,selectivity and sugar conversion of5-HMF and furfural were basically stable.The catalyst was reused five times,and the activity did not change obviously.It has good stability and recyclability.