滴流床反应器中甘油连续催化氧化制甘油酸

Continuous Catalytic Oxidation of Glycerol to Glyceric Acid in a Trickle-Bed Reactor

为了提高非碱性条件下甘油选择性氧化反应中催化剂的稳定性和目标产物的收率,在滴流床反应器中考察了碳纳米管负载Pt催化剂(Pt/CNTs)上甘油氧化反应的性能,结合热重分析、高分辨率透射电子显微镜和X射线光电子能谱等表征了反应前后催化剂的结构和性质,并优化了甘油水溶液和氧气流量、反应温度以及甘油初始浓度等工艺条件。结果表明:连续操作的滴流床反应器中,Pt/CNTs催化剂上平均吸附的产物量较少,催化剂表面Pt4f的结合能仅有少许降低,且反应后催化剂颗粒无明显团聚和活性组分浸出现象,因而表现出较高的活性和稳定性。实验确定的较优工艺条件为甘油溶液流量0.10cm^(3)/min、氧气流量20.0 cm^(3)/min、反应温度60.0℃和甘油初始质量分数10.0%,在此条件下Pt/CNTs催化剂催化甘油转化率大于80%,甘油酸的收率大于55%。

Base-free oxidation of glycerol over carbon nanotubes supported Pt catalysts(Pt/CNTs)was carried out in a trickle-bed reactor,aiming to improve the stability of the catalyst and the yield of target product.The fresh and used catalysts were characterized by means of thermal gravimetric analysis,high resolution transmission electron microscopy and X-ray photoelectron spectroscopy.The operating conditions,such as flow rates of glycerol and oxygen,reaction temperature and initial glycerol concentration were also optimized for higher yield of glyceric acid.The results showed that the catalysts tested in the trickle-bed reactor exhibit high stability,which was mainly due to relatively low amount of products adsorbed,little reduction in Pt binding energy,no obvious aggregation of Pt particles and almost no leaching of Pt.Under optimal reaction conditions with glycerol flow rate of 0.10 cm^(3)/min,oxygen flow rate of 20.0 cm^(3)/min,reaction temperature of 60.0℃and initial glycerol mass fraction of 10.0%,a yield of glyceric acid larger than 55%can be obtained with a glycerol conversion higher than 80%.