Conversion Carbohydrates Into 5-hydroxymethylfurfural Catalyzed By Schiff Base Complex Immobilized On Modified MCM-41

Fossil energy has been unable to meet the needs of the rapid development of the world economy.It is important to seek clean renewable energy to replace the traditional fossil energy.Biomass resource has attracted widespread attention as a well-stocked,broad-source and renewable energy source.Carbohydrate,as a major component of biomass energy,has important practical significance of developing and utilizing carbohydrates to prepare some high value-added platform compounds.Among them,5-hydroxymethylfurfural(HMF)as a link between carbohydrate and petroleum industry chemistry,it has a very far-reaching significance in the preparation of HMF from carbohydrates.The catalyst of Schiff base metal complex and modified MCM-41 were used to dehydration of monosaccharides into HMF in the paper.The research contents and results are as follows :(1)First,an acidic functionalized ionic liquid 1-(propyl-3-sulfonate)vinylimidazolium hydrogen sulfate([(CH2)3SO3HVIm]HSO4,IL1)was prepared and immobilized on a modified MCM-41.The heterogeneous catalyst was used to prepare HMF and showed good catalytic activity for the dehydration of fructose.A HMF yield of 86.3% was achieved from fructose using MCM-41-IL1(30 mg)as the catalyst in DMSO at 130 °C for 3 h.The properties of catalyst were characterized by a series of analyzes,the results showed that MCM-41-IL1 had good thermal stability and large specific surface area,which could be used as a good solid acid carrier.(2)A series of novel heterogeneous catalysts were prepared by immobilizing Chromium(III)Schiff base complexes onto the different groups modified MCM-41.The catalytic activity of the solid catalysts was investigated for the conversion of glucose into HMF.The effects of catalyst type,reaction temperature,time,amount of catalyst and solvent on the catalytic activity of glucose were investigated.A HMF yield of 50.2% with a 99.3% glucose conversion was achieved from glucose using Cr(Salten)-MCM-41-IL1(50 mg)as the catalyst in DMSO at 140 °C for 4 h.Furthermore,the catalyst also demonstrated good activity on other substrates such as fructose,sucrose and so on.The catalyst of Cr(Salten)-MCM-41-IL1 still remains good catalytic activity on the conversion of glucose after 5 cycles(HMF yield was 42.2%).(3)We prepared a heterogeneous catalyst via the anchoring of Zirconyl Schiff base complex on the surface of mesoporous MCM-41 and then investigated the catalytic activity of catalyst on the conversion of fructose to HMF.The effect of reaction factors on the conversion of fructose to HMF was studied by using Zr(IV)-salen-MCM-41 as catalyst.A HMF yield of 92.0% was achieved from fructose using Zr(IV)-salen-MCM-41(50 mg)as the catalyst in DMSO at 140 °C for 4 h.The catalyst also demonstrated good activity on other substrates,HMF yield of 77.4% and 84.7% was obtained when sucrose and inulin were selected as the substrates,respectively.The catalyst Zr(IV)-salen-MCM-41 can remain good catalytic activity after recycled 4 times.