**5. Conclusions**

Based on the proposed theory and simulation and experimental results, we have some conclusions to highlight as follows. Calculating and simulating adsorption columns is a very difficult task to deal with, however, with a suitable theory and mathematical tools, such as the help of computer software, we can simulate the partial pressure change of the adsorbed substance over time and in the direction height of the column. The partial pressure of the adsorbed material decreases both over time and the height of the column. The optimum working pressure of the column is 5.5 bar and adsorption time is 25 s. This simulation result is nearly accurate and has a margin of about 20% due to the rate of change, which in the simulation we calculated the speed as constant at the time of the column input. Drop pressure in this process is 0.148 bar. From the experimental research results, we understand the adsorption column uses a CMS-240 carbon molecular sieve material to separate N2 from air working in environmental, isothermal, working regime stability (pressure change over time) can separate N2 gas to reach a maximum concentration of 93%. Total pressure changes over time and decreases with column height. The optimal working mode at a pressure of 5 bar with adsorption time parameters is determined in Figure 20. Experimental results also show the mutual influence of technological parameters and the adsorption capacity of materials and columns.

The results of simulated and experimental research are very reliable on the basis of practical models and perfect laboratory equipment. The research methods and results are a solid basis for studying two columns and equipment according to the PSA cycle.

**Author Contributions:** Investigation, P.V.C., Software, H.N.N., V.D.T.; Methodology, P.V.C., H.N.N., N.T.H.; Visualization, V.D.T., T.-Y.N.; Formal Analysis, N.T.A., P.V.C. and T.-Y.N.; Writing—original draft, P.V.C., V.D.T., T.-Y.N.; Writing—review & editing, H.-N.N., D.V.T.

**Funding:** This research was funded by Institute of Technology—General Department of Defense Industry gran<sup>t</sup> number 100.02-2019.10.

**Conflicts of Interest:** The authors declare no conflict of interest.
