Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (6): 534-539.DOI: 10.6023/A20040130 Previous Articles     Next Articles

Special Issue: 多孔材料:金属有机框架(MOF)



陈杨a, 杜亚丹a, 王勇a, 刘普旭a, 李立博a,b, 李晋平a,b   

  1. a 太原理工大学化学化工学院 气体能源高效清洁利用山西省重点实验室 太原 030024;
    b 太原理工大学 煤科学与技术教育部和山西省重点实验室 太原 030024
  • 投稿日期:2020-04-29 发布日期:2020-05-26
  • 通讯作者: 李立博
  • 基金资助:

Ammonia Modification on UTSA-280 for C2H4/C2H6 Separation

Chen Yanga, Du Yadana, Wang Yonga, Liu Puxua, Li Liboa,b, Li Jinpinga,b   

  1. a College of Chemistry and Chemical Engineering, Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization, Taiyuan University of Technology, Taiyuan 030024;
    b Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024
  • Received:2020-04-29 Published:2020-05-26
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 21908155, 21922810), Natural Science Foundation for Young Scientists of Shanxi Province (No. 201901D211053) and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi.

Recovering C2H4 from refinery gas is an effective way to broaden the source of ethylene. However, it's a challenging task to separate C2H4 and C2H6 due to their very close physical properties and molecular size. Metal-organic frameworks (MOFs) are shown broad prospects in the field of light hydrocarbon separation in recent years. In this work, NH3 is used to modify the structure of UTSA-280, the efficient separation of C2H4/C2H6 can be achieved through the adjustment of one-dimensional channels. UTSA-280 has undergone stepwise adsorption of ammonia gas at 298 K and 100 kPa. After partial ammonia removal, we obtained the modified UTSA-280 that ammonia adsorption modification with a mass loading of 5.6% for UTSA-280-M1 and 2.8% for UTSA-280-M2. The NH3 modified UTSA-280 shows a unique ultramicroporous structure that can enhance the adsorption of C2H4 and does not adsorb the slightly larger C2H6, achieving the ideal C2H4/C2H6 adsorption selectivity (more than 1000). Ammonia molecules play the role of perfectly adjusting the size of one-dimensional channels and realize the ideal screening effect of C2H4/C2H6. The C2H4 adsorption capacity of NH3 modified UTSA-280-M2 can be improved to 2.83 mmol/g at 298 K and 100 kPa (an increase of 29% compared with initial material). And its ultramicroporous structure can fully block the adsorption of C2H6, which finally achieves a C2H4/C2H6 selectivity over 1200. Grand Canonical Monte Carlo (GCMC) simulation of C2H4/C2H6 mixed gases (equal volume) adsorption results showed that the modified UTSA-280 had more C2H4 adsorption distribution in the mixed components than C2H6. Through the C2H4/C2H6 mixed gases breakthrough test at 298 K, NH3 modified UTSA-280-M2 shows a separation time of more than 48 min, which is more than the initial 25 min. Compared with the unmodified material, the separation performance is nearly doubled. Scalable synthesis, stable structure, and the advantages of controllable performance after ammonia modification have prompted this material to have great prospects in the industrialization of C2H4/C2H6 separation.

Key words: metal-organic frameworks, NH3 modification, C2H4/C2H6 separation, selectivity