Dynamic Adsorption of Methyl Iodide

Dynamic adsorption experiments were executed utilizing a laboratory-scale fixed-bed reactor operating at a temperature of 150 °C. Specifically, 30 mg of adsorbent was loaded into a quartz column (4.6 mm I.D. × 200 mm) with silane-treated glass wool employed to occupy the interstitial void space. The column was subsequently activated at 150 °C for 6 h under a dry helium flow (10 mL/min). To evaluate performance under a partial pressure of 0.2 bar, a nitrogen carrier flow at a rate of 3 mL/min was directed through a CH₃I vapor generator, subsequently passing through the adsorbent-packed column at a linear velocity of 18 cm/min, corresponding to a residence time of approximately 5 s. The concentration of CH₃I in the effluent was continuously monitored using an online mass spectrometry (MS) system. The flow rate of CH₃I under these conditions was determined to be approximately 4.408 mg/min by trial and error.
To assess performance under a partial pressure of 0.01 bar, a nitrogen carrier flow at a rate of 0.3 mL/min was directed through the CH₃I vapor generator, subsequently combined with another dry nitrogen flow at a rate of 5.7 mL/min before passing through the adsorbent column. Under these conditions, the linear velocity was 36 cm/min, with a residence time of ~2.5 s. The flow rate of CH₃I under this configuration was approximately 0.426 mg/min. Experiments conducted under humid conditions (RH = 50%) at 0.01 bar involved mixing a nitrogen flow passing through the CH₃I vapor generator at a rate of 0.3 mL/min with a nitrogen flow passing through the water vapor generator at a rate of 3 mL/min, along with a dry nitrogen flow at a rate of 2.7 mL/min. The combined gas stream was then directed through the adsorbent column. Monitoring of CH₃I in the effluent was performed using an online MS system.
The adsorption capacities at breakthrough (Q_breakthrough) were determined using the following equation: $Q_{breakthrough}=\frac{v\times t_{1\%}}{m}1$ Where v represents the flow rate of CH₃I (mg/min); t_1% (corresponding to C/C₀ = 1%, min) denotes the breakthrough point when the concentration of CH₃I in the effluent stream (C) reaches 1% of the initial concentration (C₀); m signifies the weight of the adsorbent (mg).