催化学报

催化学报 ›› 2019, Vol. 40 ›› Issue (11): 1758-1765.DOI: 10.1016/S1872-2067(19)63432-7

• 论文 • 上一篇    下一篇

用于乙苯氧化脱氢制苯乙烯铝-硼催化剂:铝硼组成及制备方法对催化剂性能的影响

Nagaraju Pasupulety, Muhammad A. Daous, Abdulrahim A. Al-Zahrani, Hafedh Driss, Lachezar A. Petrov   

  1. 阿卜杜拉齐兹国王大学工程学院化工与材料工程系, 吉达 21589, 沙特阿拉伯
  • 收稿日期:2019-03-10 修回日期:2019-06-24 出版日期:2019-11-18 发布日期:2019-09-06
  • 通讯作者: Nagaraju Pasupulety, Lachezar A. Petrov
  • 基金资助:
    This project was funded by the Deanship of Scientific Research (DSR) at King Abdulaziz University, Jeddah, under grant no. (G-1281-135-1440). The authors, therefore, acknowledge with thanks DSR for technical and financial support.

Alumina-boron catalysts for oxidative dehydrogenation of ethylbenzene to styrene: Influence of alumina-boron composition and method of preparation on catalysts properties

Nagaraju Pasupulety, Muhammad A. Daous, Abdulrahim A. Al-Zahrani, Hafedh Driss, Lachezar A. Petrov   

  1. Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia
  • Received:2019-03-10 Revised:2019-06-24 Online:2019-11-18 Published:2019-09-06
  • Contact: Nagaraju Pasupulety, Lachezar A. Petrov
  • Supported by:
    This project was funded by the Deanship of Scientific Research (DSR) at King Abdulaziz University, Jeddah, under grant no. (G-1281-135-1440). The authors, therefore, acknowledge with thanks DSR for technical and financial support.

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摘要： 采用溶胶-凝胶（SG）法合成了不同摩尔比的Al-B催化剂（Al-10B与Al-35B）.在450-500℃，乙苯（EB）接触时间为0.54 g-cat.s.cm-3的条件下，在氧气和水蒸气存在下对这些催化剂进行催化乙苯脱氢反应.利用NH3-TPD质谱分析了Al-B催化剂的酸性.扫描电镜图像显示，硼在氧化铝中负载量达15%（Al-15b）时仍分布很好，而在较高的硼含量（Al-25B和Al-35B）催化剂中观察到硼聚集.从本质上讲，在Al和Al-10B催化剂上观察到强度非常弱（Tmax ≤ 125℃）的酸位，使得EB转化率和苯乙烯产率很低.另一方面，在Al-25B和Al-35B催化剂酸位较弱（Tmax ≤ 180℃），因而EB转化率较高.然而，在弱-中等强度酸位的Al-15B催化剂上可以得到较高的苯乙烯产率（43.2%）和合理的EB转化率（46%）.另外，采用共沉淀法（COP）和浸渍法（IMP）合成了Al-15B催化剂.IMP和COP催化剂的NH3-TPD-质谱分析结果发现，与NOx形成有关的酸位点在500℃时将EB转化率分别提高到66%和63%.然而，Al-B SG催化剂中的这些酸位降低，使得500℃时EB转化率为50%.当EB转化率为50%时，在Al-B IMP，Al-B COP和Al-SG催化剂上苯乙烯选择性分别为73%，82.5%和84%.因此，不同方法制备的Al-B催化剂，会产生不同强度和密度的酸位，从而影响苯乙烯的形成.

关键词: 铝-硼, 氧化脱氢, 乙苯, 苯乙烯, 共沉淀

Abstract: Different mole ratio Al-B catalysts (Al-10B to Al-35B) were synthesized by using sol-gel (SG) method. Ethyl benzene (EB) dehydrogenation in the presence of oxygen and water steam was carried out on these catalysts at 450-500℃ with EB contact time of 0.54 gcat.s.cm-3. Acidity of Al-B catalysts was estimated by using NH3-TPD-mass spectral analysis studies. SEM-mapping images revealed fine distribution of boron up to 15% of its loading in alumina (Al-15B), whereas, boron aggregation was observed in higher boron content (Al-25B and Al-35B) catalysts. Essentially, acid sites of very weak strength (Tmax ≤ 125℃) were observed for Al and Al-10B catalysts and resulted in low EB conversion and styrene yield. On the other hand, acid sites of weak strength (Tmax ≤ 180℃) were observed for Al-25B and Al-35B catalysts and resulted in high EB conversion. However, greater styrene yield (43.2%) with reasonable EB conversion (46%) was obtained on acid sites of weak moderate strength in Al-15B catalyst. Further, Al-15B catalyst was synthesized by using co-precipitation (COP) and impregnation (IMP) methods. Acid sites related to NOx formation during the NH3-TPD-mass analysis on IMP and COP catalyst essentially improved the EB conversion to 66% and 63% respectively at 500℃. However, these acid sites were diminished in Al-B SG catalyst and resulted in 50% of EB conversion at 500℃. At 50% of EB conversion level, styrene selectivity of 73%, 82.5% and 84% were observed on Al-B IMP, Al-B COP and Al-SG catalysts, respectively. Hence, different method of preparation of Al-B catalyst generated acid sites of different strength and density and thereby influenced the styrene formation.

Key words: Alumina-boron, Oxidative dehydrogenation, Ethyl benzene, Styrene, Co-precipitation