(377n) Capture of Alkynes from Hydrocarbon Mixtures with Multi-Functional Metal-Organic Framework By Combining Molecular Recognition and Size-Sieving

Qingju Wang; Xili Cui; Zhaoqiang Zhang; Lifeng Yang; Huabin Xing*

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

E-mail: xinghb@zju.edu.cn

Selective one-step removal of all the alkynes from pyrolysis gases is a challenging but important technology in the production of polymer-grade olefins. The currently existed selective removal technology, front-end hydrogenation, is unable to achieve the deep removal of several kinds of alkynes simultaneously due to the complex compositions of pyrolysis gases (including C1-C5 fractions). Therefore, the revolution to the current separation technology to further simplify the process is necessary and urgent. Adsorptive separation technology, with the characterizations of energy-efficient and deep removal, would be a promising technology. However, the conventional adsorbents can hardly specifically capture multi-type alkynes and propadiene from mixed cracking gas. In addition, the existing adsorbent can also adsorb higher hydrocarbons easily. Hence, it remains a daunting challenge to design an ideal material that can not only selectively adsorb multi-type alkynes and propadiene, but also exclude higher hydrocarbons. Here we prepare a multi-functional metal-organic framework with high-density of anions and suitable pore size for the capture of multi-type alkynes and propadiene from mixed cracking gas. The unique hydrogen-bonding properties of inorganic anions can achieve the specific recognition of the acetylene, propyne and propadiene, meanwhile, the exclusion of higher hydrocarbons by precisely tuning of pore cavity size. The adsorption isotherms and dynamic breakthrough experiment all confirm the unprecedented separation performance. The underlying interactions between gas and porous material are explored by modeling studies.

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

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