Clathrate Hydrate-Based Carbon Capture: A Laboratory Experiment

Clathrate hydrate-based carbon dioxide separation technology was applied to a laboratory experiment using a mixed gas of carbon dioxide and nitrogen. From October 2022 to August 2024, this experiment was offered to 16 groups comprising 109 second- and third-year undergraduate students. The experiment was also conducted in a high school lecture involving a total of 16 participants. To ensure safety, a glass pressure vessel enclosed in a polycarbonate casing was used at a maximum pressure of 1.5 MPa. Under low temperatures and high pressures, carbon dioxide and nitrogen reacted with a tetra-n-butylammonium aqueous solution to form clathrate hydrates, which preferentially incorporate carbon dioxide. By measuring the gas composition before and after hydrate formation, it was confirmed that carbon dioxide was consumed, thereby lowering its fraction. Based on the measured temperature, pressure, and gas-phase composition data, students tackled exercise problems requiring them to calculate the composition within the clathrate hydrates by applying the equation of state to the gas phase before and after clathrate hydrate formation. Assessment was based on written reports. An analysis employing The Revised Taxonomy verified that the experiment covered a broad spectrum of both Knowledge and Cognitive Process domains. Consequently, many students reached the learning objectives, resulting in a 93% pass rate with an average passing score of 86 out of 100.