退火温度对Ni-B非晶态合金催化苯丙酮酸胺化加氢反应性能的影响

Catalytic Performance of Amorphous Ni-B Alloy Annealed at Different Temperatures for the Amination and Hydrogenation of Phenylpyruvic Acid

研究了纳米非晶态Ni-B合金催化剂对于苯丙酮酸胺化加氢合成苯丙氨酸的催化性能。结果表明,Ni-B非晶态合金催化剂比传统催化剂雷尼镍和漆原镍具有更优异的活性和选择性,在Ni-B催化作用下,苯丙氨酸的产率和选择性分别高达94.15%和94.80%。同时,研究了退火温度对催化活性的影响。结果表明,在473 K退火处理2 h后的Ni-B催化剂催化合成苯丙氨酸的产率最高,为95.28%。随着退火温度的升高,Ni-B催化剂的催化活性急剧下降。结合XRD、XPS和TEM等表征手段,发现镍的富电子效应是非晶态合金催化剂具有较高活性和选择性的主要原因,而高温退火处理会导致催化剂发生团聚和晶化,进而降低催化剂的反应活性。

It was investigated that the preparation of phenylalanine （Phe） from phenylpyruvic acid （PPA） by amination and hydrogenation over nanosized amorphous Ni-B alloy catalyst. It had been found that the amorphous Ni-B alloy catalyst exhibited superior activity and selectivity to the traditional catalysts Raney Ni and Urushibara Ni. The yield and selectivity of Phe over Ni-B catalyst reached 94. 15% and 94. 80%, respectively. At the same time, the catalytic activities of amorphous Ni-B alloy annealed at various temperatures were investigated for the hydrogenation of PPA to Phe. The results indicated that the yield of Phe reached a maximum （95.28%）for the amorphous Ni-B alloy catalyst annealed at an optimized temperature of 473 K. A higher annealing temperature led to a dramatic decrease in the catalytic activity of Ni-B alloy. These catalysts were characterized by XRD, XPS and TEM. Based on the characterizations, the higher activity and selectivity of the amorphous Ni-B alloy catalyst for the preparation of Phe were mainly ascribed to the electron-rich Ni due to electron donation from alloying B. Whereas, the aggregation of nano-crystalline Ni resulted in the active decrease of Ni- B sample.