## 3 Experimental Investigation  
### Adsorbent Performance Testing Device  
The testing device is mainly consisted of heating/cooling unit, adsorption/desorption unit, data-collecting unit, vacuum ball valve, and pipes, the schematic diagram and photograph are shown in Figures 2 and 3. The heating/cooling unit comprises an electric heating furnace, a temperature  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**No.**} & **Types of Composite** & **Times of** & **Heating** & **Heating** \\  & **adsorption** & **Washing** & **Temperature/(\({}^{\circ}\)C)** & **Time/(h)** \\ \hline CA5X & 5 wt \% CaCl\({}_{2}\)—13X & 4 & 300 & 10 \\ CA10X & 10 wt \% CaCl\({}_{2}\)—13X & 4 & 300 & 10 \\ CA15X & 15 wt \% CaCl\({}_{2}\)—13X & 4 & 300 & 10 \\ CA20X & 20 wt \% CaCl\({}_{2}\)—13X & 4 & 300 & 10 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Washing and activating of composite adsorbents.  
Figure 1: 13X/CaCl\({}_{2}\) composite adsorbent.  
controller, and a blower which can control the heating and cooling of the adsorption bed well. The electric heating furnace consists of a stainless steel case, high-temperature-resistant insulation cotton, and electrically-heated wire. The electric heating furnace will provide heat for the adsorbent bed in the process of thermal vacuuming and desorption. The furnace has a strong point of simple operation, quick heating, good thermal insulation, and security. The blower is connected to the bottom inlet of the furnace through a soft pipe, which can provide the adsorbent bed the ambient temperature air to cool the furnace in the later process of thermal vacuuming and adsorption. Thus, the heating/cooling unit can effectively heat or cool the adsorbent bed.  
The adsorption/desorption unit includes a cylindrical adsorbent bed, evaporator/condenser, and a vacuum pump. The adsorbent bed is made of stainless steel. The inside diameter, height, and thickness of the adsorbent bed are 59 mm, 150 mm, and 2 mm respectively. The volume of the bed is about 410 mL which can be fully filled with 287 g zeolite 13X (3-5 mm). There are three absorb  
Figure 3: Photograph of adsorbent performance testing device.  
Figure 2: Schematic diagram of adsorbent performance testing device. 1—adsorbent bed, 2—adsorbent channel, 3—heating furnace, 4—temperature controller, 5—air inlet valve, 6—air inlet, 7—blower, 8—air outlet valve, 9—air outlet, 10—Flange, 11—vacuum ball valve 1, 12—vacuum ball valve 2, 13—pressure transmitter, 14—vacuum ball valve 3, 15—vacuum ball valve 4, 16—evaporator/condenser, and 17—vacuum pump.  
channels made of expanded metal in the cylindrical adsorbent bed, and the adsorbent bed connects to the system by two flanges, a seal washer, and four pairs of bolts and nuts to ensure it is leak-proof and convenient to install. The electric heating furnace can effectively heat the adsorbent through the cylindrical stainless steel. The evaporator/condenser consists of a flow calibration tube which comprises a stainless steel case and a glass blind tube with volume tick marks inside. The vacuum pump is a rotary-vane vacuum pump that is produced by Shanghai Second Vacuum Pump Factory Co., Ltd., Shanghai, China. The model number of the vacuum pump is XD-10 which means its pumping rate can reach 10 m\({}^{3}\)/h. Thus, the process of adsorption/desorption can be conducted under relative vacuum conditions.  
The data-collecting unit includes K type thermocouples with a measurement accuracy of 10\({}^{-3}\)\({}^{\circ}\)C and range from \(-\)200 \({}^{\circ}\)C to 1372 \({}^{\circ}\)C, a pressure transmitter range from 0 Pa to 5 kPa and measurement precision of 10\({}^{-4}\) Pa, an Agilent data acquisition instrument, and an all-in-one PC, which can accurately collect temperature and pressure data during the continuous process.