NiFeB非晶态合金催化剂催化麦芽糖加氢反应

Hydrogenation of Maltose over NiFeB Amorphous Alloy Catalyst

采用化学还原法制备了NiFeB非晶态合金催化剂,通过X射线衍射、透射电子显微镜等技术对该催化剂的结构、形貌进行了研究。以麦芽糖加氢制备麦芽糖醇为探针反应,考察了还原剂KBH_4加入量、Fe加入量对NiFeB非晶态合金催化剂活性的影响。实验结果表明,NiB非晶态合金中引入Fe并没有改变它的非晶态结构,仅增大了NiB非晶态合金非晶态合金的结构无序度,使催化剂具有磁性,呈链状骨架结构。NiB非晶态合金中引入适量Fe后,催化剂粒径大小相对均匀,提高了活性组分的分散度,活性组分Ni更富电子,提高了催化剂的加氢活性。当n(Fe):n(Ni+Fe)=0.25、n(KBH_4):n(Ni+Fe)=5、反应压力3.0 MPa、反应温度100℃、搅拌转速800 r/min、反应时间3h时,麦芽糖的转化率达100.0%。

NiFeB amorphous alloy catalysts with different Fe contents were prepared by chemical reduction method and used as catalysts for hydrogenation of maltose to maltitol. Their physicochemical properties were characterized by mecns of XRD and TEM. Investigation of NiFeB amorphous alloy focused on effects of Fe content and reducing agent KBH4 dosage in preparation. Addition of Fe does not change amorphous state of NiB catalyst, but enhance the amorphous degree. When Fe content is suitable, NiFeB amorphous alloy catalyst is larger in surface area, more rich in unsaturated Ni active sites and more heavy in electron density of active sites, therefore exhibits much higher hydrogenation activity in comparison with NiB catalyst. The morphology of NiFeB particles is quite different from NiB, spherical in shape and relatively even in diameter, and trend to aggregate chains due to magnetic properties of Fe. When NiFeB was used as catalyst in hydrogenation of maltose, under the optimal conditions ： n （Fe） ： n （ Ni ＋ Fe） 0.25, n （ KBH4 ） ： n （ Ni ＋ Fe） 5, reaction pressure 3.0 MPa, reaction temperature 100℃ ,stirring speed 800 r/min and reaction time 3 h, conversion of maltose can reach 100.0%.