Title : Comparative study of zeolite-5A and Cu-BTC for CO2 adsorption using thermodravimetric analyzer in the application of hydrogen
Abstract:
Hydrogen is considered as one of the most important clean and renewable energy carriers for a sustainable energy future. However, its efficient and cost-effective purification remains challenging. This paper presents the potential of using metal–organic frameworks (MOFs) in combination with pressure swing adsorption (PSA) technology for syngas based H2 purification. PSA process analysis is done considering high pressure and elevated temperature process conditions, it reduces the demand for off-gas recycle to the fuel reactor and simultaneously permits higher desorption pressure, thereby reducing the parasitic load on the hydrogen compressor. The elevated pressure and temperature adsorption we present here is beneficial to minimizing overall process heating and cooling demand compared to existing processes.
Here, we report the comparative performance of Ni-MOF-74, Cu-BTC and the mix of Ni-MOF-74/Cu-BTC for H2 purification from syngas typical of those exiting water-gas-shift reactors. The MOFs were synthesized hydrothermally and then mixed systematically at different weight ratios to find the optimum composition based on the adsorption performance. The formation of different compounds were characterized by XRD, N2 adsorption and desorption, SEM, FT-IR, TG and water vapor adsorption technologies. Single-component adsorption isotherms of CO2, CO, CH4, N2, and H2 over single materials and composites were measured at elevated pressures and different temperatures to determine their equilibrium adsorption capacity. The examination of the stability and regeneration performance of metal–organic frameworks was carried out using a gravimetric system at temperature ranges of 25-300? for a pressure range of 0-30 bar. The studies of adsorption/desorption on the MOFs showed selective adsorption of CO2, CH4, CO and N2 over H2. Overall, the findings of this study suggest that the Ni-MOF-74/Cu-BTC composites are promising candidates for industrial H2 purification processes.
Audience take-away:
- In literature, most PSA units operate at atmospheric temperature for better adsorption of gases. This study will help to evaluate PSA at high pressure and temperature that will minimize the process cost when considering not only the PSA unit, but also the systems integrated with the PSA unit. Therefore, the researchers from this field will have justification for the study of various adsorbents that could be stable enough at these conditions.
- MOF’s stability at high pressure and temperature has not been broadly reported before. Therefore, the audience could learn more details about the synthesis and performance of different MOFs at operating conditions of importance to this study.
- In this study, the adsorption and desorption were done at elevated pressures. The syngas leaves the shift reactor at elevated pressure and keeping this pressure high reduces demands for off-gas recycle to the fuel reactor. In addition, the higher desorption pressure reduces the parasitic loads on the hydrogen compressors. Therefore, it simplifies the downstream power requirement of different hydrogen purification processes.
