催化学报 ›› 2019, Vol. 40 ›› Issue (5): 722-732.DOI: 10.1016/S1872-2067(18)63269-9

• 论文 • 上一篇    下一篇

三维有序大孔钙钛矿型La1–xKxNiO3催化剂提高炭烟催化燃烧活性:K取代的作用

梅雪垒, 熊靖, 韦岳长, 王楚君, 吴强强, 赵震, 刘坚   

  1. 中国石油大学(北京)理学院, 重质油加工国家重点实验室, 北京 102249
  • 收稿日期:2018-10-23 修回日期:2018-11-21 出版日期:2019-05-18 发布日期:2019-03-30
  • 通讯作者: 韦岳长
  • 基金资助:

    国家自然科学基金(21673142);移动源排放控制技术国家工程实验室(NELMS2017A05);中国石油创新基金(2018D–5007–0505);中国石油大学(北京)科学基金(242017QNXZ02,2462018BJC005).

Three-dimensional ordered macroporous perovskite-type La1-xKxNiO3 catalysts with enhanced catalytic activity for soot combustion: the Effect of K-substitution

Xuelei Mei, Jing Xiong, Yuechang Wei, Chujun Wang, Qiangqiang Wu, Zhen Zhao, Jian Liu   

  1. State Key Laboratory of Heavy Oil Processing, College of Science, China University of Petroleum-Beijing, Beijing 102249, China
  • Received:2018-10-23 Revised:2018-11-21 Online:2019-05-18 Published:2019-03-30
  • Contact: 10.1016/S1872-2067(18)63269-9
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21673142), National Engineering Laboratory for Mobile Source Emission Control Technology (NELMS2017A05), PetroChina Innovation Foundation (2018D-5007-0505), and Science Foundation of China University of Petroleum, Beijing (242017QNXZ02, 2462018BJC005).

摘要:

催化炭烟燃烧的本质是典型的固体(炭烟颗粒)-固体(催化剂)-气体(O2和NO)三相深度氧化反应.因此炭烟燃烧性能不仅与催化剂的本征活性有关,同时也与催化剂和炭烟颗粒之间的接触效率有关.钙钛矿型(ABO3)氧化物具有高热稳定性和高催化活性,在钙钛矿型氧化物中A位通常为稀土元素,B位通常为过渡金属元素,钙钛矿的A,B位离子都可以被半径相近的其他元素部分取代,而且物相结构不发生变化.我们组前期研究发现,用碱金属部分取代钙钛矿型氧化物中的A位,可以有效提高其催化活性.同时发现三维有序大孔(3DOM)结构可以有效的增加催化剂与碳烟颗粒的接触效率.基于此,本文利用胶体晶体模板法成功制备了3DOM La1-xKxNiO3钙钛矿型催化剂,并采用SEM,TEM,HRTEM,Elements mapping,XRD,Raman,XPS和H2-TPR等手段对其物理化学性能进行了表征,进一步探讨K取代对3DOM La1-xKxNiO3催化剂炭烟催化燃烧性能的影响.
SEM和TEM照片显示,制备的3DOM La1-xKxNiO3催化剂孔道三维有序贯通,孔径均一,孔壁厚度均匀,每个大孔下面展示清晰可见的小孔窗,大孔孔径大约为260 nm,这有利于炭烟颗粒在气流的协助下进入催化剂的孔道之内,从而提高炭烟与催化剂之间的接触效率.3DOM结构催化剂具有大的比表面积(24-27 m2g-1),且K的取代对其比表面积无太大的影响.XRD和Raman谱证实了催化剂的钙钛矿结构,且K能够取代La并进入钙钛矿氧化物的晶格中.XPS和H2-TPR表征发现,K取代La之后,B位的Ni元素的价态有所提升,表面活性氧物种密度增加,其中3DOM La0.95K0.05NiO3催化剂具有最高的Ni4+的含量和活性氧含量.3DOM La1-xKxNiO3催化剂展示了高的炭烟燃烧催化性能,且K的取代能够明显促进其催化炭烟燃烧活性.在松散接触条件下,催化剂炭烟催化燃烧活性的顺序为:3DOM La0.95K0.05NiO3 > 3DOM La0.90K0.10NiO3 > 3DOM La0.80K0.20NiO3 > 3DOM La0.99K0.01NiO3 > 3DOM LaNiO3 > particle-type LaNiO3.其中,3DOM La0.95K0.05NiO3催化剂展示了最高的炭烟燃烧催化性能,其T50SCO2值分别为338℃和98.2%,这与Pt基催化剂活性相当.另外,对炭烟催化燃烧性能的影响因素进行了探讨:一方面,三维有序大孔结构有效提高催化剂活性;另一方面,K元素的取代提高了Ni的价态,从而提升了表面活性氧物种数量,这对炭烟催化燃烧起着至关重要的作用.

关键词: 三维有序大孔材料, 镍酸镧, 钾, 钙钛矿, 炭烟燃烧

Abstract:

Three-dimensional ordered macroporous (3DOM) La1-xKxNiO3 perovskite-type catalysts were successfully prepared by a colloidal crystal template method and characterized by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray scattering elemental mapping, X-ray diffraction, Raman and X-ray photoelectron spectroscopy, and temperature-programmed reduction of H2. Further, their catalytic activity in soot combustion was determined by temperature-programmed oxidation reaction. K substitution into the LaNiO3 lattice led to remarkably improved catalytic activity of this catalyst in soot combustion. Amongst various catalysts, La0.95K0.05NiO3 exhibited the highest activity in soot combustion (with its T50 and SCO2 values being 338℃ and 98.2%, respectively), which is comparable to the catalytic activities of Pt-based catalysts under the condition of poor contact between the soot and the catalyst. K-substitution improves the valence state of Ni and increases the number of oxygen vacancies, thereby leading to increased density of surface-active oxygen species. The active oxygen species play a vital role in catalyzing the elimination of soot. The perovskite-type La1-xKxNiO3 nanocatalysts with 3DOM structure without noble metals have potential for practical applications in the catalytic combustion of diesel soot particles.

Key words: Three-dimensional ordered, macroporous material, LaNiO3 Potassium, Perovskite, Soot combustion