WO3/Nb2O5固体酸催化果糖制备5-羟甲基糠醛

Preparation of 5-hydroxymethylfurfural from fructose catalyzed by WO3/Nb2O5

摘要:

采用浸渍法制备氧化铌负载氧化钨固体酸催化剂，用XRD、EDS、TEM、NH3-TPD、Py-IR、BET、BJH对催化剂的结构、组分、形貌、酸性、比表面积及孔径等进行表征；并将其用于催化果糖转化为5-羟甲基糠醛( HMF) 反应，对氧化钨负载量、反应时间、反应温度、催化剂用量等影响因素进行考察。结果表明，氧化钨负载量对催化剂结构、酸性以及催化活性均有影响：随着WO3负载量的增加，氧化钨分子从表面分散的非晶态WO3转变为结晶WO3，且Nb2O5上适量的WO3产生大量强酸位点，使催化剂的Brønsted酸含量增加，从而使果糖的转化率得到提高；但结晶WO3却不利于HMF的生成。当氧化钨的负载量为5%时 ，在催化剂加入量为100mg，170 ℃条件下反应1 h，HMF选择性 较高为85.4%，收率可达49.6%。

Abstract:

A series of WO3/Nb2O5 was prepared by impregnation method. The structure, components, morphology, acidic property, specific surface area and porosity of the catalysts were fully characterized by XRD, EDS, TEM, NH3-TPD, Py-IR, BET, BJH. And its catalytic properties in conversion of fructose to 5-hydroxymethylfurfural (HMF) are studied. The factors such as tungsten oxide loading amount, reaction time, temperature and amount of catalyst are investigated. It is found the tungsten oxide loading amount plays important role on the structure, acidic property and catalytic properties of the catalysts. With the increase of tungsten loading amount, the molecular structure of tungsten oxide changes from the surface dispersed amorphous WO3 to the crystalline WO3, and the presence of appropriate amount of WO3 clusters on Nb2O5 leads to generation of maximum number strong acidic sites and additional number of Brønsted acid sites in the catalyst, thereby increasing the conversion of fructose. However, the crystalline WO3 is not conducive to the production of HMF. The selectivity and yield of HMF can respectively reach 85.4% and 49.6% within 1 h at 170 ℃ over 100 mg 5%-WO3/Nb2O5 catalyst．