(381ar) Purification of Ethylene with Anion-Pillared Metal-Organic Frameworks As Adsorbents

Purification of ethylene with anion-pillared metal-organic
frameworks as adsorbents

Qi Ding, Xili Cui, Zhaoqiang Zhang, Lifeng Yang, Huabin Xing*

College of
Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027

E-mail: xinghb@zju.edu.cn

As
an important feedstock in petrochemical industries, ethylene (C₂H₄)
is among the highest-yield chemicals in the world with a global production
capacity of more than 170 MT in 2016. Separation of C₂H₄ from
acetylene (C₂H₂) and ethane (C₂H₆) present
as critical steps in preparing polymer-grade C₂H₄, which
meanwhile exhibit great challenge due to the similar molecular size and
physical properties of these light hydrocarbons and are generally realized by
energy-extensive cryogenic distillation or solvent absorption, these processes accounting
for nearly 85% of the total cost for C₂H₄ production. Adsorption
based on porous materials is a commercially viable alternative technology for
gas purification, while the ever reported adsorbents usually meet with the trade-off
between uptake capacity and selectivity, confining their ultimate separation ability.
In the presentation, we will discuss strategies addressing the problem and
recent advances of our group in the context of ethylene purification. We reveal
that finely control of pore chemistry and pore size in anion-pillared ultramicroporous metal-organic frameworks (MOFs) enables
the materials brilliant performance for C₂H₂/C₂H₄
separation through exploiting supermolecular host-guest
and/or guest-guest interactions. Furthermore, the tactic to give an overall
consideration to adsorption thermodynamics and adsorption kinetics and take
advantage of their synergetic effect leads to outstanding molecular recognition
ability to C₂H₄ over C₂H₆.
Impressive adsorptive selectivities setting new
benchmarks were achieved in our work accompanied by high gas uptake.^1,2
The excellent performances of the anion-pillared ultramicroporous
MOFs were confirmed by single-component static and kinetic adsorption, and multi-component
break through experiments. The binding sites of C2 hydrocarbons on the materials
were explored by DFT-D (dispersion-corrected density-functional theory)
calculations to give insights into the interaction mechanisms.

Acknowledgement:

This research was
supported by the National Natural Science Foundation of China (No. 21725603),
Zhejiang Provincial Natural Science Foundation of China (No. LZ18B060001), the
National Program for support of Top-notch Young Professionals (H. X.) and China
National Petroleum Corporation.

References:

1.     Cui
XL, Chen KJ, Xing HB, et al. Pore chemistry and size control in hybrid porous
materials for acetylene capture from ethylene. Science. 2016; 353(6295): 141-144.

2.     Zhang
ZQ, Cui XL, Yang LF, et al. Hexafluorogermanate (GeFSIX) anion-functionalized hybrid ultramicroporous
materials for efficiently trapping acetylene from ethylene. Ind. Eng. Chem. Res. 2018; 57:
7266-7274.