催化学报

催化学报 ›› 2016, Vol. 37 ›› Issue (5): 727-734.DOI: 10.1016/S1872-2067(15)61068-3

• 论文 • 上一篇    下一篇

铁氧体吸附剂的穆斯堡尔谱解析及其反应吸附脱硫性能

陈霄a, 朱凯新b,c, M. A. Ahmedd, 王军虎b, 梁长海a   

  1. a 大连理工大学化工学院先进材料与催化工程实验室, 辽宁大连 116012;
    b 中国科学院大连化学物理研究所穆斯堡尔数据中心, 辽宁大连 116023;
    c 中国科学院大学, 北京 100049;
    d 艾资哈尔大学理学院物理系, 开罗, 埃及
  • 收稿日期:2016-01-13 修回日期:2016-02-21 出版日期:2016-04-26 发布日期:2016-04-26
  • 通讯作者: Junhu Wang, Changhai Liang
  • 基金资助:

    国家自然科学基金(21373038,21403026,21476232);中国博士后基金(2015T80255,2014M551068);中-埃科技交流项目(21311140474).

Mössbauer spectroscopic characterization of ferrites as adsorbents for reactive adsorption desulfurization

Xiao Chena, Kaixin Zhub,c, M. A. Ahmedd, Junhu Wangb, Changhai Lianga   

  1. a Laboratory of Advanced Materials and Catalytic Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012, Liaoning, China;
    b Mössbauer Effect Data Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    c University of Chinese Academy of Sciences, Beijing 100049, China;
    d Physics Department, Faculty of Science, Al Azhar University, Cairo, Egypt
  • Received:2016-01-13 Revised:2016-02-21 Online:2016-04-26 Published:2016-04-26
  • Contact: Junhu Wang, Changhai Liang
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21373038, 21403026, and 21476232), the China Postdoctoral Science Foundation (2015T80255 and 2014M551068), and the China-Egypt Scientific-Technologic Exchange Project (21311140474).

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摘要：

运输燃料中的含硫化合物依然是空气污染的主要源头. 随着人们环保意识日益增强, 世界各国对燃料油标准特别是硫含量提出了越来越严格的要求. 为了应对燃料油的无硫化趋势, 探索新型脱硫技术去除油品中的含硫化合物成为研究热点. 吸附脱硫技术 (ADS) 能够选择性地脱除汽油中的含硫化合物, 而不影响其中的烯烃含量, 从而避免了加氢精制过程中烯烃饱和导致的辛烷值降低问题, 成为目前成熟的清洁油品生产技术.
本文采用微波辅助燃烧技术, 将一定化学计量比的金属硝酸盐和尿素混合物快速燃烧反应, 成功合成一系列铁氧体吸附剂 (MgFe2O4, NiFe2O4, CuZnFe2O4, ZnFe2O4, CoFe2O4). 以含有噻吩的正庚烷 (总含硫量 3000 mg/L) 为汽油模型, 在固定床反应器中 500 ℃ 反应条件下探索了所合成铁氧体吸附剂的吸附脱硫性能. 结果表明, 铁氧体吸附脱硫活性大小为: MgFe2O4 > NiFe2O4 > CuZnFe2O4 > ZnFe2O4 > CoFe2O4. 其中 MgFe2O4 较其他铁氧体具有更高的吸附脱硫性能. 这是由于 Mg-Fe 合金化程度低, 而且掺杂的 Mg 降低了 Fe 与 S 之间的相互作用, 从而显著提高了吸附脱硫性能. 此外, Mg 作为一种典型的碱金属可在一定程度上显著促进噻吩分解.
X 射线衍射和穆斯堡尔谱作为敏感的结构和组成检测手段, 广泛用于解析铁氧体吸附剂在吸附脱硫过程中的结构和相态变化. 通过穆斯堡尔谱成功解析了铁氧体中 Fe 的存在形式及其化合态. 对新鲜铁氧体吸附剂、吸附脱硫后的吸附剂以及氧化再生的吸附剂进行监测对比, 发现在吸附过程中铁氧体被部分硫化成 Fe1-xS 和双金属硫化物. 在空气中经高温 (500 ℃) 处理可成功实现铁氧体吸附剂再生. 本文通过对铁氧体吸附剂的结构解析和性能测试, 为新型吸附脱硫剂开发提供了理论依据.

关键词: 铁氧体, 吸附脱硫, 穆斯堡尔谱, 再生

Abstract:

Sulfur in transportation fuels is a major source of air pollution. New strategies for the desulfurization of fuels have been explored to meet the urgent need to produce cleaner gasoline. Adsorptive desulfurization (ADS) is one of the most promising complementary and alternative methods. Herein, nanocrystalline ferrite adsorbents were synthesized from metal nitrates and urea using a microwave assisted combustion method. A series of ADS experiments were performed using a fixed-bed reactor to evaluate the ADS reactivity over the ferrites, which was found to have the order MgFe2O4 > NiFe2O4 > CuZnFe2O4 > ZnFe2O4 > CoFe2O4. This effect is explained by the fact that the low degree of alloying of Mg-Fe and the doped Mg increased the interaction between Fe and S compounds, leading to a significant improvement in the desulfurization capability of the adsorbent. Additionally, Mg can dramatically promote the decomposition of thiophene. X-ray diffraction and Mössbauer spectroscopy were used to characterize the fresh, regenerated, and sulfided adsorbents. Although the ferrite adsorbents were partially sulfided to bimetallic sulfides during the adsorption process, they were successfully regenerated after calcining at 500 ℃ in air.

Key words: Ferrite, Adsorptive desulfurization, Mössbauer spectroscopy, Regeneration