Separation of Alkynes from Olefins for Polymer Production

November 12, 2020
Separation of Alkynes from Olefins for Polymer Production
Chemoselective separation of acetylene (C2H2) from ethylene (C2H4) by Ni-decorated faujasite. Acetylene molecules are trapped by the Ni sites while ethylene molecules can flow through. Image: Jill Hemman (ORNL)

Scientific Achievement

Chemoselective alkyne/olefin separation by a nickel decorated zeolite was found to occur via binding of acetylene to the confined Ni through formation of metastable [Ni(C2H2)3] complexes.

Significance and Impact

Understanding and controlling porous sorbants, like zeolites, can lead to cheaper and more efficient separation of alkynes from olefin, a costly step in the polymer processing of lower olefins (ethylene, propylene, etc.).

Research Details

  • Ni-decorated faujasite, a zeolite, was produced confining atomically dispersed Ni into zeolite channels.
  • In situ neutron diffraction and spectroscopy combined with density functional theory calculations revealed that the Ni sites interact much more strongly with alkynes than with olefins, leading to the excellent selectivity. 
  • The material also exhibits high dynamic uptake of alkynes, thanks to the large specific surface area of the porous faujasite.

“Control of zeolite pore interior for chemoselective alkyne/olefin separations”
Yuchao Chai1, Xue Han2, Weiyao Li2, Shanshan Liu1, Sikai Yao1, Chong Wang3, Wei Shi4, Ivan da-Silva5, Pascal Manuel5, Yongqiang Cheng6, Luke D. Daemen6, Anibal J. Ramirez-Cuesta6, Chiu C. Tang7, Ling Jiang3, Sihai Yang2, Naijia Guan1,4, Landong Li1,4, 
Science, 368, 1002 (2020). 
DOI: 10.1126/science.aay8447