Yu Qiao,Yonghou Xiao,Shuohan Yang,Qidong Zhao,Wenkai Zhao,Gaohong He
Recently, the investigation of high-efficiency adsorbents for CO adsorption and separation has gradually become a research focus with carbon energy chemistry developing and environmental protection requirement enhancing. The adsorption performance of CO would be devitalized under a humid environment, although the traditional molecular sieves could serve as an effective adsorbent toward CO adsorption under an anhydrous atmosphere. In this work, a strategy of silanization modification was proposed to enhance the performance of CO adsorption by restraining the surface occupied by competitive water molecules due to the hydrophilic nature of silica hydroxyl groups on the 5A molecular sieves. A series of hydrophobic CO adsorbents (X-B-5A) were successfully prepared via impregnation using butyltrichlorosilane (BTS) as a hydrophobic agent, toluene as a dispersion solution, and commercial 5A molecular sieves as a raw material. The effect of different concentrations of BTS in toluene solution on hydrophobicity and CO adsorption performance was investigated. The results showed that the hydrophobicity of X-B-5A was significantly increased after silanization modification. Additionally, the water contact angle of 0.004-B-5A increased from 20° to 154°, and the static water vapor adsorption capacity was reduced from 27.5 to 6.0% at 35 °C. The CO static adsorption capacity of 0.004-B-5A still reached 1.54 mmol/g, which was only 14.6% lower than that of pristine 5A molecular sieves. Additionally, the dynamic adsorption capacity of CO over the as-prepared X-B-5A was significantly enhanced compared to pristine 5A molecular sieves in the presence of moisture. The as-prepared hydrophobic adsorbents exhibited satisfactory CO adsorption performance and high thermal stability in a humid environment. This work presents a novel strategy for the preparation of adsorbents toward CO adsorption employed under a high relative humidity environment.
Qiang Guo,Yu Qiao,Yonghou Xiao,Yi Pan,Yushan Li,Xu Liu,Gaohong He
Cuprous ion modified molecular sieves have been considered as promising CO adsorbents in gas separation or purification industry. However, it persists as a significant challenge to overcome the unfavorable effect of water vapor in the work environment on gas adsorption and separation. Herein, we propose a synthetic strategy using rare earth element La as an additive to form La O La coordination bonds followed by surface silanization treatment to construct a hydrophobic Si O Si barrier to significantly improve the stability of Cu + under humid atmosphere. By successively introducing La 3+ and Cu + into zeolite 5A, CuCl/LaA adsorbents were prepared via ion exchange and solid dispersion methods. And then by silanization modification using toluene as solvent and butyltrichlorosilane (BTS) as hydrophobic agent, hydrophobic CuCl/LaA-BTS adsorbents were prepared. Dynamic adsorption investigation demonstrated that the as-prepared CuCl/LaA-BTS adsorbents possessed hydrophobic surface and consequently the adsorption capacity of CO was enhanced significantly under humid atmosphere. The CO adsorption breakthrough capacity over CuCl/LaA-BTS attained 0.34 mg/g, which was 5.7 times higher than that of zeolite 5A at 40 °C, atmospheric pressure and a relative humidity of RH = 55 %. Moreover, the CO adsorption capacity of CuCl/LaA-BTS retained 0.31 mg/g after four cycle regenerations. This work provides an effective and novel route for synthesizing highly stable cuprous ion modified zeolite adsorbents.
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