Coalbed Methane Hydrate Separation: An Experimental Study Using Ordered Mesoporous Materials

Coalbed methane (CBM), a major unconventional natural gas, is considered an essential energy source and a substitute for traditional fossil fuels, such as oil and coal, because of its abundant reserves and environmentally friendly characteristics. It mainly consists of methane but also includes nitrogen, oxygen, etc. Among them, methane is the most valuable to be utilized. Therefore, methane separation and purification from CBM are of great importance. The gas separation technology based on the hydrate approach has been considered a suitable, cleaner, and promising approach to recovering methane from CBM compared to other methods. Compared with other CBM components, methane can preferentially synthesize gas hydrate. Hence, methane can be separated from other gas components in CBM as hydrate to achieve energy recovery. For this, two main parameters, hydrate formation kinetics and energy recovery efficiency, need to be optimized experimentally. In this study, a series of CBM hydrate separation experiments were performed using ordered mesoporous materials, SBA-15 and MCM-41. We examined the variation characteristics of the hydrate formation rate and gas storage capacity at the mesoscopic scale and comprehensively analyzed the strengthening effect of the two mesoporous materials during the CBM separation process. The results show that the hydrate synthesis rate in the MCM-41 was higher than that in SBA-15 under the same thermodynamic conditions, while the effective gas storage capacity of SBA-15 was higher than that of MCM-14. This difference became smaller with increasing pressure. The gas storage rate can reach more than 85% of the final gas storage capacity within 15 min in entire experiments. Thus, both mesoporous materials had their advantages in promoting hydrate synthesis. These findings of this study can provide a better understanding for studies on separating and purifying CBM to achieve energy efficiency.