K2CO3-Impregnated Al/Si Aerogel Prepared by Ambient Pressure Drying for CO2 Capture: Synthesis, Characterization and Adsorption Characteristics

Materials

Yan Jin¹  Yanlin Wang¹  Baihe Guo¹  Jingnan Guo¹  Man Zhang²  Hairui Yang² 

[1] College of Electrical and Power Engineering, Taiyuan University of Technology, Taiyuan 030024, China;Department of Energy and Power Engineering, Tsinghua University, Beijing 100000, China;

关键词: Al/Si aerogel;    surface modification;    potassium-based adsorbent;    CO₂ adsorption performance;    adsorption kinetics;   

DOI  :  10.3390/ma13173741

来源: DOAJ

【 摘 要 】

A new potassium-based adsorbent for CO₂ capture with Al aerogel used as support is proposed in this work. The adsorbents with different surface modifiers (tetraethyl orthosilicate (TEOS) and trimethyl chlorosilane (TMCS)) and different K₂CO₃ loadings (10%, 20%, 30% and 40%) were prepared by sol-gel and iso-volume impregnation processes with ambient pressure drying. The CO₂ adsorption performance of the adsorbents were tested by a fixed-bed reactor, and their adsorption mechanisms were studied by scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray fluorescence spectrometry (XRF). Furthermore, the adsorption kinetics and the cycling performance were investigated. The results show that using TEOS to modify the wet gel can introduce SiO₂ to increase the strength of the skeleton. On the basis of TEOS modification, TMCS can further modify –OH, thus effectively avoiding the destruction of aerogel structure during ambient drying and K₂CO₃ impregnation. In this work, the specific surface area and specific pore volume of Al aerogel modified by TEOS + TMCS are up to 635.32 cm²/g and 2.43 cm³/g, respectively. The aerogels without modification (Al-B), TEOS modification (Al/Si) and TEOS + TMCS modification (Al/Si-TMCS) showed the best CO₂ adsorption performance at 20%, 30% and 30% K₂CO₃ loading, respectively. In particular, the CO₂ adsorption capacity and K₂CO₃ utilization rate of Al/Si-TMCS-30K are as high as 2.36 mmol/g and 93.2% at 70 degrees Celsius (°C). Avrami’s fractional order kinetic model can well fit the CO₂ adsorption process of potassium-based adsorbents. Al-B-20K has a higher apparent activation energy and a lower adsorption rate during the adsorption process. After 15 adsorption-regeneration cycles, Al/Si-TMCS-30K maintain a stable CO₂ adsorption capacity and framework structure, while the microstructure of Al/Si-30K is destroyed, resulting in a decrease in its adsorption capacity by nearly 30%. This work provides key data for the application of Al aerogel in the field of potassium-based adsorbent for CO₂ capture.

【 授权许可】

Unknown