CO2 accounts for approximately 77% of the world's greenhouse gas emissions, which come from the combustion of coal, oil, and natural gas. Soon, given the continued use of fossil fuels as the backbone of electricity generation worldwide, strategies to reduce CO2 emissions are essential, especially in developing countries. In the gas industry, CO2 is a serious corrosive agent, especially in its dissolved form. In gas production, CO2 gas is not a decomposition agent. Carbon dioxide gas in contact with the electrochemical process of steel must be in aqueous and soluble phase. CO2 gas combines with H2O gas to form H2CO3, making the liquid acidic. In this project, the potential of MOFs with coordinated unsaturated sites was investigated, which shows promising and cheap methods for post-combustion carbon adsorption with high-pressure separation processes. Post-synthetic modification of MIL-101(Fe) and MIL 101(Cr)-NH2 frameworks was performed with a series of amines at different loadings. In the case of modified MIL-101 (Fe), a slight improvement in natural gas absorption capacity was observed at ED loading of 2.5 and 3 wt%. However, it was observed that the modified PEI samples were inactive to increase the adsorption capacity of natural gas. According to dry cycling studies, absorption is reversible for most materials. But the obtained results showed that the materials are not effective for post-combustion absorption due to their relatively low work capacity. Wet cycling tests indicated a high H2O absorption capacity, which resulted in a lower working capacity of natural gas compared to dry conditions. Interestingly, saturation of the materials by H2O absorption was not observed during the test time at 25 °C except for MIL-101(Fe)-ED when 1 vol% H2O was used in the feed gas stream. Compared with MIL-101(Fe), MIL-101(Fe) modified with 3 wt% ED and PEI loading exhibited higher work capacity under wet conditions at 25 °C. The type of amine, loading, temperature and pressure strongly influenced the adsorption capacity of natural gas by modified MIL-101(Cr)-NH2. With increasing PEI loading, the optimal adsorption temperature was obtained at higher temperatures due to faster kinetics at higher temperatures. Although PSM materials were almost saturated with natural gas at low pressures, high pressure absorption was investigated for MIL-101(Cr)-NH2. Comparison of the sorption capacity obtained in this work with the reported data for MIL-101(Cr)-NH2 showed that higher sorption capacities can be obtained through MIL-101(Cr) PSM. Therefore, improvement in the synthesis process of prefunctionalized MIL-101 (Cr)-NH2 is necessary.
