(401be) Development of CuCl-Supported Nanoporous Adsorbent Exhibiting High Performances (Adsorption Capacity and Selectivity) of Carbon Monoxide Separation, and Strong Resistance to Oxidation under Atmospheric Condition

Carbon monoxide (CO) is produced in various industrial fields including steam reforming process, partial oxidation and steelmaking process [1]. Especially in the steelmaking process, CO was emitted within off-gas streams such as coke oven gas, blast furnace gas and Linz-Donawitz gas. The concentration of CO in those off-gas is 20~80%, and the amount of annul emission of CO in Republic of Korea is approximately three million ton. The CO gas generated in the steelmaking field is generally burned off in the form of CO₂ to recover energy. However, if CO can be separated from the off-gas, CO can be better utilized as a precursor of high-valued chemicals such as acetic acid, poly-urethane, polycarbonate, formic acid, acrylic acid and phosgene, instead of emitting a greenhouse gas, CO₂. In addition, CO is recently expected to be highly used in the form of syn-gas to synthesize gasoline via Fischer-Tropsch catalytic process. There have been various methods to separate CO, such as cryogenic distillation, absorption method, and adsorption method [2,3]. Cryogenic distillation is commonly used in large-scale CO separation in various fields. However, this process is highly-energy demanding for maintaining cryogenic condition. In addition, it is quite challenging to separate CO and nitrogen which show quite similar boiling point. In the case of absorption method, CuAlCl₄ dissolved in toluene is normally used as absorbent, and this process is called as COSORB process. This method is highly advantageous for the generation of high-purity CO gas and recovery rate. However, toluene can be sometimes disposed to harmful species and Cu⁺ ion can be easily oxidized during the process. Adsorption method such as pressure swing adsorption is quite promising, and this process is especially suitable for medium-scale CO separation process. This process requires low energy consumption and low cost for process operation. In this method, the separation performance of adsorbent is very important. Development of new adsorbent can make innovation of the adsorption process.

We have developed nanoporous adsorbent supporting CuCl, which exhibits notable performance in selective adsorption of CO. The adsorbent was prepared impregnating CuCl on nanoporous materials via thermal dispersion or impregnation method. In this work, we could find new supporting material which exhibits unexpected characteristics. This supporting material shows high affinity of CuCl, so that exhibiting high adsorption capacity for CO, and extremely low affinity to CO₂. In these reasons, new CO adsorbent synthesized using this supporting material exhibits high adsorption capacity of CO (32 cm³ g^-1) and extremely low adsorption capacity of CO₂ (2.8 cm³ g^-1) under 100 kPa of each gas at 293 K. Thus, this adsorbent exhibits excellent CO/CO₂ separation coefficient higher than 10. In addition, we have developed simple method of pelletizing new adsorbent to show reasonable rigidity. More interestingly, new adsorbent is highly resistant to oxidation of CuCl under atmospheric condition. This result is quite notable, as considering the fact that CuCl is easily oxidized in air. The oxidation of CuCl can cause the dramatic decrease of the adsorption capacity of CO. Our new adsorbent can maintain CO adsorption capacity after six-month exposure to air. More detail results of the material synthesis and CO adsorption analysis will be presented in 2017 AICHE annual meeting. New developed material will be promising adsorbent for selective separation of CO from combustion exhaust and off-gas stream of various industry fields. Furthermore, it can be used as highly-performing adsorbent in separation processes of Ï€-bond-containing species such as olefin and sulfur.

[1] Y. Xie, J. Zhang, J. Qiu, X. Tong, J. Fu, G. Yang, H. Yan, Y. Tang, Adsorption 3 (1996) 27.

[2] F. Kasuya, T. Tsuji, Gas Sep. Purification 5 (1991) 242.

[3] F. Gao, Y. Wang, S. Wang, Chem. Eng. J. 290 (2016) 418.