催化学报 ›› 2020, Vol. 41 ›› Issue (4): 679-690.DOI: 10.1016/S1872-2067(19)63523-0

• 论文 • 上一篇    下一篇

Co3O4-CeO2氧化物对丙烷完全氧化的催化性能

朱文军a,b, 陈霄a, 金建辉a, 邸鑫a, 梁长海a, 刘中民b   

  1. a 大连理工大学精细化工国家重点实验室, 先进材料与催化工程实验室, 辽宁大连 116024;
    b 中国科学院大连化学物理研究所, 中国科学院洁净能源创新研究院, 甲醇制烯烃国家工程实验室, 辽宁大连 116023
  • 收稿日期:2019-08-22 修回日期:2019-09-30 出版日期:2020-04-18 发布日期:2019-12-12
  • 通讯作者: 梁长海, 刘中民
  • 基金资助:
    国家重点研发计划(2016YFB0600305).

Insight into catalytic properties of Co3O4-CeO2 binary oxides for propane total oxidation

Wenjun Zhua,b, Xiao Chena, Jianhui Jina, Xin Dia, Changhai Lianga, Zhongmin Liub   

  1. a State Key Laboratory of Fine Chemicals & Laboratory of Advanced Materials and Catalytic Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China;
    b Methanol to Olefins National Engineering Laboratory, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
  • Received:2019-08-22 Revised:2019-09-30 Online:2020-04-18 Published:2019-12-12
  • Supported by:
    This work was supported by the National Key R&D Program of China (2016YFB0600305).

摘要: 挥发性有机化合物(VOCs)是全球大气污染物的主要来源,近年来已造成严重的环境问题.催化氧化是一种有效的、经济可行的VOCs去除技术,其研究的关键在于开发高效、稳定的催化剂.在本文中,我们采用柠檬酸法合成了一系列具有不同Co/(Ce+Co)摩尔比的Co3O4-CeO2二元氧化物催化剂,研究了其对丙烷(低碳VOCs)的催化氧化性能.
在催化活性测试中,反应气的组成为0.2 vol.% C3H8和5 vol.% O2,Ar为平衡气,气体总流速为200mL min-1.实验结果表明,Ce的掺入能够明显提高Co3O4的丙烷催化氧化性能,Co3O4-CeO2催化剂的丙烷催化氧化活性顺序为CoCeOx-70 > CoCeOx-90 > Co3O4 > CoCeOx-50 > CoCeOx-20 > CeO2.当Co/(Ce+Co)摩尔比为70%时,CoCeOx-70催化剂的丙烷催化氧化性能最好.在丙烷转化率达到90%时,CoCeOx-70催化剂的反应温度为310℃(GHSV=120000mL h-1 g-1),相比于单一的Co3O4催化剂的反应温度降低了25℃.
XRD和TEM表征结果显示,在Co3O4-CeO2二元氧化物催化剂中存在Co3O4和CeO2两种晶型,同时随着Ce的掺入,催化剂的粒径明显降低.Raman光谱图显示,Ce的掺入使催化剂的晶格发生畸变,促进催化剂表面氧空位的产生,为催化剂中氧的迁移提供晶格位点.H2-TPR和C3H8-TPSR结果表明,Co3O4与CeO2间存在相互作用,能够提高催化剂的低温还原性能,以促进催化剂的丙烷催化氧化.O2-TPD和O 1s XPS结果表明,Ce的掺入能够增加催化剂表面活性氧物种的产生,提高催化剂中氧的移动性,从而提高了催化剂对丙烷的催化氧化活性.在对Co3O4和CoCeOx-70催化剂进行in-situDRIFTS表征和简单的动力学研究,我们发现Ce的掺入不改变催化剂的丙烷催化氧化反应路径,其存在能够促进丙烷在催化剂表面的吸附和活化,以提高催化剂的丙烷催化氧化活性.同时,丙酮和酯作为中间物参与到丙烷的催化氧化反应过程中.
此外,我们考察了反应气氛中水蒸气和CO2的存在对催化剂催化性能的影响.结果表明,CO2和水蒸气的存在都抑制了催化剂的丙烷催化氧化活性,催化性能随着CO2和水蒸气浓度的增加而降低.在相同条件下,水蒸气对催化剂催化性能的抑制作用明显大于CO2的抑制作用,但这种抑制作用会随着反应气中水蒸气和CO2的消失而消失.在稳定性测试中,CoCeOx-70催化剂表现出优异的抗水蒸气和CO2性能.在反应气中存在5 vol.%水蒸气和5 vol.% CO2的条件下,CoCeOx-70催化剂在50 h的稳定性测试中均未出现明显的失活现象.同时,经过10次加热和降温循环测试后,催化剂的催化活性也没有发生明显变化,这为CoCeOx-70催化剂的未来工业化的应用提供了可能.

 

关键词: 丙烷, 完全氧化, Co3O4-CeO2, 原位漫反射傅里叶变换红外光谱, 挥发性有机化合物

Abstract: A series of Co3O4-CeO2 binary oxides with various Co/(Ce+Co) molar ratios were synthesized using a citric acid method, and their catalytic properties toward the total oxidation of propane were examined. The activities of the catalysts decrease in the order CoCeOx-70 > CoCeOx-90 > Co3O4 > CoCeOx-50 > CoCeOx-20 > CeO2. CoCeOx-70 (Co/(Ce+Co)=70% molar ratio) exhibits the highest catalytic activity toward the total oxidation of propane, of which the T90 is 310℃ (GHSV=120000 mL h-1 g-1), which is 25℃ lower than that of pure Co3O4. The enhancement of the catalytic performance of CoCeOx-70 is attributed to the strong interaction between CeO2 and Co3O4, the improvement of the low-temperature reducibility, and the increase in the number of active oxygen species. In-situ DRIFTS and reaction kinetics measurement reveal that Ce addition does not change the reaction mechanism, but promotes the adsorption and activation of propane on the catalyst surface. The addition of water vapor and CO2 in reactant gas has a negative effect on the propane conversion, and the catalyst is more sensitive to water vapor than to CO2. In addition, CoCeOx-70 exhibits excellent stability and reusability in water vapor and CO2 atmosphere.

Key words: Propane, Total oxidation, Co3O4-CeO2, In-suit DRIFTS, Volatile organic compounds

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