## 3 Results and Discussion
### Dynamic Adsorption and Temperature Control Tests  
Dynamic adsorption-desorption tests for HVPM were firstly conducted using a small-scale apparatus to test the regeneration and reuse performance of HVPM. Results were shown in Figure 9. For the first-time adsorption of toluene, HVPM had an adsorption capacity of 0.32 g toluene/g HVPM. Three adsorption-desorption cycles were subsequently conducted, and the synthesized adsorbent only showed a 0.03 g/g decrease in adsorption capacity. The ratio of the adsorption capacity and the previous adsorption capacity was over 0.93, which also suggests good regeneration performance.  
Using a self-designed adsorption column, which enables real-time inner-column temperature recording, temperature-control capability of the synthesized HPVM was tested. Two adsorption tests were carried  
Figure 8: Pore size distribution of HVPM.  
Figure 9: Regeneration and reuse performance of HVPM.  
out using (i) activated carbon (40 g), (ii) activated carbon (40 g) and HVPM (20 g), as adsorbents. Toluene was used as adsorbate. The temperature of the adsorbents and inlet gas was set at 45 \({}^{\circ}\)C, using an oven and water bath, respectively. The breakthrough curves of the two experiments are shown in Figure 10. Initial toluene concentration and flow rate were both high so there was toluene found at the gas exit at the beginning. The adsorption capacities of activated carbon and HVPM were 0.31 and 0.21 g/g, respectively. The value was determined by weighing the adsorbents after the adsorption process. The result shows the considerable adsorption capability of HVPM.  
Figure 11a shows the real-time inner-column temperature, using activated carbon as an adsorbent. Adsorption started at 0 min and, at 0 cm, the temperature started to increase because of released heat due to the adsorption. As the adsorption occurred from bottom to top of the column, the temperature at 5 cm subsequently increased because of heat transferred from the lower position and the released heat of the adsorption. The highest temperature in the column reached near 49.5 \({}^{\circ}\)C. As the activated carbon in the lower position reached saturation adsorption, the temperature at 0 cm slowly decreased. Finally, as adsorption was completed, the temperature at different locations decreased. The onset time of the temperature-decreasing trend at 5 cm corresponded to the saturation adsorption time (around 320 min) indicated by the breakthrough curve in Figure 10. The final temperature was lower than the initial temperature because of the heat transfer between column and air.  
Figure 11b shows the real-time inner-column temperature using activated carbon and HPVM as an adsorbent. A similar thermal behavior was observed, compared to Figure 10a. However, the final highest temperature was around 47.4 \({}^{\circ}\)C. Around 1.2 \({}^{\circ}\)C, the temperature rise occurred in the second experiment, in contrast with 3.2 \({}^{\circ}\)C in the pure activated carbon adsorption experiment, indicating a 62.5% decrease in temperature rise. The large difference in temperature rise is because the wax in HVPM stores the heat released from adsorption as it undergoes phase transition. The temperature-buffer characteristic of HVPM also results in a lower gradient, both in temperature rise and temperature drop, as seen in Figure 11b. Even for this small-scale adsorption test, the temperature rise was high in the column of activated carbon adsorption, as shown in Figure 10a, and the synthesized HVPM shows a capability of controlling the inner-column temperature during the adsorption process, as expected.  
Figure 10: Breakthrough adsorption curves of (i) activated carbon (AC); (ii) AC and HVPM toward toluene. (Temperature: 45 \({}^{\circ}\)C; feed flow rate: 0.90 L/min; initial toluene concentration: 65,000 ppm).