Dynamic Adsorption/Desorption of NO x on MFI Zeolites: Effects of Relative Humidity and Si/Al Ratio

• Published in: Nanomaterials (Basel, Switzerland) Vol. 13; no. 1
• Main Authors: Tao, Haiyang, Liu, Yingshu
• Format: Journal Article
• Language: English
• Published: Switzerland 29.12.2022
• Subjects: flue gas; water vapor; Si/Al; MFI zeolites; NOx adsorption
• ISSN: 2079-4991; 2079-4991

Adsorption is a potential technology that is expected to meet NO ultra-low emission standards and achieve the recovery of NO . In this study, the adsorption/desorption behavior of NO with competitive gases (e.g., H O(g) and CO ) was studied on MFI zeolites with different Si/Al ratios and under different relative humidity (0~90% RH). Sample characterization of self-synthesizing zeolites was conducted by means of X-ray diffraction, Ar adsorption-desorption, and field emission scanning electron microscopy. The results showed that low-silica HZSM-5(35) showed the highest NO adsorption capacity of 297.8 μmol/g (RH = 0) and 35.4 μmol/g (RH = 90%) compared to that of other adsorbents, and the efficiency loss factor of NO adsorption capacity at 90%RH ranged from 85.3% to 88.1%. A water-resistance strategy was proposed for NO multicomponent competitive adsorption combined with dynamic breakthrough tests and static water vapor adsorption. The presence of 14% O and lower adsorption temperature (25 °C) favored NO adsorption, while higher CO concentrations (~10.5%) had less effect. The roll-up factor ( ) was positively correlated with lower Si/Al ratios and higher H O(g) concentrations. Unlike Silicalite-1, HZSM-5(35) exhibited an acceptable industrial desorption temperature window of NO (255~265 °C). This paper aims to provide a theoretical guideline for the rational selection of NO adsorbents for practical applications.