## 3 Results
### Residual Gas in Nanopores of Undegassed and Degassed Mixture  
Figure 2 are photos of glycerol/zeolite mixture taken after different treatment conditions, which show the gas content of the system before and after degassing treatment. Figure 2a is taken after glycerol/zeolite mixture placing at room temperature in a drying condition for 12 h, which demonstrates the gas content of an undegassed system. It is seen that there are a great amount of air bubbles suspended in the mixture. These small bubbles cannot surface because of the viscosity resistance of the liquid. Figure 2b is taken after placing the glycerol/zeolite mixture in vacuum for 12 h, representing the gas content of a degassed system. After 12 h' vacuum degassing, there are no visible bubbles in the system. However, we still carry out a more strict residual air test to estimate the amount of air that stayed in the zeolite's nanopores for degassed mixtures. The following paragraphs are the detailed procedural and analysis of the residual air test of the degassed system. Figure 2c is taken after the residual air test. The bubbles on the surface of the mixture prove that the used degassing treatment under normal temperature cannot eliminate air in nanopores completely. The residual air test is conducted with a DZF-6000 vacuum drying oven (Xi'an Yu Hui Experimental Apparatus, Xi'an, China). Put the degassed mixture in the vacuum drying oven, and vacuumize the oven to the maximum vacuum degree (0.003 MPa). Then, start the heating schedule of the oven to elevate the inside temperature. With the increase of temperature, the residual air in zeolite will get out of the porous channel gradually; meanwhile, the changing temperature and the pressure of the vacuum drying oven are recorded. Thus, the amount of air that is released from nanopores under certain temperatures can be calculated through the ideal gas law. The real gas can be considered as ideal gas when both molecular size and inter molecular attractions could be neglected. The test temperature is from 303.15 to 373.15 K and the test pressure is from approximate vacuum to atmosphere. For a large volume at lower pressures, because the average distance between adjacent molecules becomes much larger than the molecular size, the neglect of molecular size becomes less important for lower densities. On the other side, with increasing temperatures, the relative importance of intermolecular attractions diminishes with increasing thermal kinetic energy. Therefore, the ideal gas law can be applied. Since the absolute vacuum is unavailable, there is still air left in the oven at the highest vacuum degree. In addition, the vacuum drying oven may leak during heating process. A reference test with the same volume of pure glycerol is carried out. For both reference test and test with the degassed mixture, the temperature inside the oven is set to increase from 303.15 to 373.15 K, and the pressure  
Figure 2: Photos of glycerol/zeolite mixture taken after different treatment. variation is recorded during heating. Both pure glycerol and glycerol/zeolite mixture are vacuum degassing pretreated before test. For reference test, there is:  
\[pV_{0}=n_{0}\mathrm{R}T \tag{1}\]  
where, \(p\) is the absolute pressure inside the vacuum drying oven, \(V_{0}\) is the volume of the vacuum drying oven, which is a constant and can be measured in advance, \(n_{0}\) is the moles of air released during reference test, R is the ideal gas constant, and \(T\) is the temperature inside the vacuum drying oven. For test with glycerol/zeolite mixture, there is:  
\[pV_{0}=(n_{0}+\Delta n)\mathrm{R}T \tag{2}\]  
where, \(\Delta n\) is the amount of air released from nanopores under a certain temperature.