Production Of 5-hydroxymethylfurfural By Catalytic Conversion Of Biomass Raw Materials

The contradiction between the diminishing of non-renewable resource reserves and the increasing demands for fuels,as well as the environmental pollution caused by overuse and exploitation of fossil resources,has become a huge challenge for mankind.Renewable biomass,which has the characteristics of friendly environment,abundant reserves and low cost,has been regarded as the most ideal new energy source.Recently,a great deal of efforts have been devoted to the process of acid catalyzed hydrolysis of biomass to produce a series of monosaccharides followed by their further preparation into different high-value platform compounds.Among them,5-hydroxymethylfurfural because of its multifunctional molecular structure is considered a "top building block chemical" and then by people in-depth study.In this paper,5-hydroxymethylfurfural was prepared by using CrPO₄,FePO₄ and Fe/β zeolite as the catalysts.Numerous biomass feedstocks were investigated as substrates in a biphasic system.The effects of reaction time,reaction temperature,and reaction systems on the catalytic activity of the catalyst were investigated.The highest yield of 83% and 63% of 5-hydroxymethylfurfural were achieved using CrPO₄ as the catalyst,fructose and glucose as reaction materials under the optimum reaction conditions of 140 ℃,15 min and 140 ℃,30 min.Moreover,CrPO₄ also showed good catalytic activity for more complex structures of cellulose and lignocellulose.The yield of 5-hydroxymethylfurfural was up to 72% and 50%,respectively,under the optimum reaction conditions of 140 ℃,15 min and 160 ℃,60 min,using fructose and glucose as raw materials and environmental friendly FePO₄ as catalyst.After the completion of the reaction,the FePO₄ catalyst dissolved in the aqueous phase at high temperature re-precipitates,showing the characteristics of temperature-controlled phase transfer,thus reducing the difficulty of separation of the catalyst.Moreover,the FePO₄ catalyst still exhibited a high catalytic activity after 5 consecutive cycles.Meanwhile,a 44% 5-hydroxymethylfurfural yield and 88% furfural yield were obtained under the optimum reaction conditions with FePO₄ and NaH2PO₄ as the co-catalyst.Acetic acid,furan compounds,aromatic compounds and other high-value chemicals can be obtained through the pyrolysis of solid residuesWe used a bi-functional Fe/β zeolite as catalyst to catalyze dehydration of glucose into 5-HMF and its reaction mechanism.A maximuim HMF yield of 61% was obtained under optimum reaction conditions.As the L/B ratio is 1.19,there could be an optimal balance between the isomerization rates of glucose-to-fructose and fructose dehydration to HMF.The extra-framework isolated Fe species are shown to be the active sites for the isomerization of glucose into fructose in the conversion of glucose.