## 4 Results and Discussion
### Parametric Study on Hydrogen Purification Performance
#### 4.3.5 Effect of AC/Zeolite 13X Ratio  
This section explores the impact of the AC/zeolite 13X ratio on PSA cycle performance. The purification performance of adsorption beds with different structural configurations is investigated, including layered and single-layer beds composed exclusively of AC or zeolite 13X. The results are presented in Figure 13.  
The results indicate that the purification performance of the zeolite 13X single-layer bed surpasses that of the AC bed. Moreover, incorporating zeolite 13X or AC into the other single-layer bed significantly enhances the purification performance of the adsorption bed. Notably, the enhancement resulting from adding zeolite 13X to a single-layer activated  
Figure 11: Influence of AD time on the purification of PSA.  
carbon (AC) bed is more pronounced. When the AC/zeolite 13X ratio is adjusted from 10:0 to 9:1, hydrogen purity increases from 86.28% to 91.73%, while recovery improves from 47.38% to 48.19%. Further decreasing the AC/zeolite 13X ratio to 5:5 leads to continued improvements in both the hydrogen purity and recovery. At AC/zeolite 13X = 5:5, purity reaches its maximum value of 97.38%. At AC/zeolite 13X = 3:7, recovery peaks at 49.13%. The recovery across different layered beds is relatively similar, with a maximum difference of approximately 1%. In contrast, the variation in hydrogen purity is more significant. The optimal bed configuration should be determined based on the specific purity and recovery requirements of the intended application. Additionally, it is worth noting that the purity and recovery of the zeolite 13X single-layer bed are higher than those of the 9:1 ratio but lower than those of the 8:2 ratio. This may indicate that when the proportion of zeolite 13X in the adsorption bed is too low, its purification performance cannot be effectively utilized.  
The results of the parametric studies highlight a trade-off between hydrogen purity and recovery. Several key results are specifically summarized in Table 4. To identify optimal solutions, the findings of this study can serve as a foundation for further exploration using multi-objective optimization algorithms to determine the best operating conditions, bed configurations, and corresponding hydrogen purity and recovery. Future work will consider the parameter range and incorporate multi-beds with larger size and multi-step approaches to better align with the requirements of industrial-scale studies. In large-scale  
Figure 12: Influence of P/F ratio on the purification of PSA.  
Figure 13: Influence of AC/zeolite 13X ratio on the purification of PSA.  
industrial hydrogen production, operating conditions, such as the feed pressure and feed flow rate, are significantly higher than those at laboratory scale. For example, PSA systems for SMR hydrogen purification typically operate at around 20 bar. Additionally, increasing the number of beds and steps further enhances both purity and recovery [23]. Hydrogen productivity and energy consumption can also be considered to further improve the overall PSA performance. Additionally, the model developed in this work can be not only further extended but also used to investigate the hydrogen purification performance of other advanced adsorbent materials such as MOFs. Such efforts will enhance the performance of hybrid layered configurations.