提出了一种利用果糖低温快速热解制备5-羟甲基糠醛(HMF)并联产糠醛(FF)副产物的方法。通过Py-GC/MS(快速热解-气相色谱/质谱联用)实验,研究果糖快速热解的产物分布特性以及温度对HMF生成的影响。结果表明,HMF是果糖低温快速热解的最主要产物,在350℃下可获得最大产率,在250℃下可获得最高纯度,相对峰面积含量高达81.2%。此外,通过密度泛函理论计算,研究果糖热解形成HMF的五条可能反应途径。计算结果表明,果糖热解形成HMF的能量最优途径为路径1,即果糖首先发生C2位羟基与C1位氢的脱水,再发生C3位羟基与C1位羟基氢的脱水,最后发生C4位羟基与C5位氢的脱水而形成HMF。
Low-temperature fast pyrolysis of fructose offered a promising way to produce 5-hydroxymethyl furfural(HMF) together w ith furfural(FF) as an important by-product.In this w ork,pyrolysis-gas chromatography / mass spectrometry(Py-GC / MS) measurements w ere performed to investigate the product distribution from fast pyrolysis of fructose;the effects of pyrolysis temperature on the HMF formation behaviors w ere considered.The results indicated that HMF is the predominant product from the fast pyrolysis of fructose;the product mixture w ith highest content of HMF(81.2%,determined by the gas chromatography peak areas) is obtained at 250 ℃,w hile the maximal yield of HMF is achieved at 350 ℃.Five possible pathw ays of HMF formation from fructose w ere considered by density functional theory(DFT).The DFT calculation results suggested that pathw ay 1 is most energetically favored,i.e.fructose molecule first undergoes a dehydration process by losing-OH at C2 and-H at C1 and then it is subjected to subsequent dehydrations involving-OH at C3 and-H of hydroxyl group at C1 as w ell as-OH at C4 and-H at C5,to form HMF.