Abstract:

A boron phosphate/silica oxide (BPO₄/SiO₂) catalyst with fibrous structure after calcination was prepared by electrospinning. The effects of BPO₄ loadings and calcination temperatures of the catalysts on the structure and catalytic performance for oxidative dehydrogenation of propane (ODHP) were investigated. Studies have found that the calcination process reduces the fiber diameter. With the increase of BPO₄ loading, the activity of propane oxidative dehydrogenation increased. The BPO₄/SiO₂ catalyst calcined at 600℃ with BPO₄ loading of 7%(mass) showed the best catalytic performance for ODHP. The conversion rate of propane and the yield of propylene for the catalyst at the reaction temperature of 480℃ reached 17.0% and 13.0%, respectively. Meanwhile, the stability test indicated that the catalyst was stable during the reaction. The results showed that when the calcination temperature was low (550℃), the organic molecules in the catalysts were not completely removed, resulting in low olefin selectivity. However, the SiO₂ structure shrank tightly and inhibited the exposure of the active phase with the high calcination temperature (700℃). The catalytic activity of the nanofibrous catalyst was much higher than the conventional bulk BPO₄ catalyst at the same conditions, demonstrating that the structure could expose more active sites.

Key words: alkanes, oxidative dehydrogenation, fiber, nano-structure, electrospinning, catalyst, boron phosphate

摘要：

通过静电纺丝法制备了一种高温焙烧后具有纤维状结构的磷酸硼/二氧化硅（BPO₄/SiO₂）催化剂，并考察了BPO₄负载量和焙烧温度对该催化剂的结构和催化丙烷氧化脱氢性能的影响。研究发现焙烧过程使纤维直径减小。随着BPO₄负载量的增加，丙烷氧化脱氢活性增高。当BPO₄负载量为7%（质量分数），焙烧温度为600℃时，BPO₄/SiO₂催化剂具有最佳的催化性能；在反应温度为480℃下，丙烷转化率和丙烯产率分别达到17.0%和13.0%，且催化剂稳定性良好。当焙烧温度较低时（550℃），催化剂中的有机物分子未被除尽，导致烯烃的选择性偏低；当焙烧温度较高时（700℃），SiO₂结构收缩紧密，抑制了活性相的暴露。由于纤维结构可暴露更多活性位点，该催化剂较相同条件下粉末状BPO₄催化剂有着更高的催化活性。

关键词: 烷烃, 氧化脱氢, 纤维, 纳米结构, 静电纺丝, 催化剂, 磷酸硼