Single-bed Pressure Swing Adsorption Research Articles

Pressure swing adsorption of Li exchange hierarchical X zeolite for pure hydrogen from binary gas mixture

This study reports the separation of pure hydrogen (H2) employing pressure swing adsorption (PSA). The Li-X and Li-hierarchical X (Li–H-X) zeolite were prepared by an ion exchange process. The sorbents were evaluated through several experiments including, breakthrough, empty bed contact time (EBCT), single-bed, and two-bed PSA with different steps. The effect of pressure, purity, and recovery relationship was developed. The high-pressure PSA study was performed at 4, 6, and 10 bar with varying feed flow rates to assess their efficacy in pure H2 separation using binary gas stream (H2/CO2, 75/25 vol.%). The breakthrough adsorption capacity of Li–H-X exhibited 3.4 mmol g−1 and 0.212 mmol g−1 of CO2 and H2, respectively. Li–H-X shows ∼8% higher CO2 sorption capacity than the Li-X sorbent at 1 bar and 300 K due to the large meso-microporous structure of the sorbent. The two-bed PSA purity and recovery were found higher than single-bed PSA. Using two-bed PSA, the Li–H-X achieved a 99.5% of purity, 92.9% of recovery, and 10.4 mL min−1 g−1 of productivity, which was ∼16% higher recovery and productivity than single-bed PSA at a flow rate of 1200 mL min−1 at 6 bar. With increasing the pressure and flow rate, the recovery of Li–H-X was enhanced up to 93.7% with 99.1%–99.9% H2 purity. The long-term PSA was run using Li–H-X sorbent for 7.5 h with 230 cycles with H2 purity between 98.5 and 99.5% at 6 bar. Interestingly, the adsorbent shows the scalability of PSA for efficient H2 separation for a binary mixture of H2/CO2.

High pressure adsorption isotherms of nitrogen onto granular activated carbon for a single bed pressure swing adsorption refrigeration system

Adsorption characteristics of nitrogen onto granular activated carbon for the wide range of temperature (303–323 K) and pressure (0.2027–2.0265 MPa) have been reported for a single bed pressure swing adsorption refrigeration system. The experimental data were fitted to Langmuir, Dubinin-Astakhov and Dubinin-Radushkevich (D-R) isotherms. The Langmuir and D-R isotherm models were found appropriate in correlating experimental adsorption data with an average relative error of ±2.0541% and ±0.6659% respectively. The isosteric heat of adsorption data were estimated as a function of surface coverage of nitrogen and temperature using D-R isotherm. The heat of adsorption was observed to decrease from 12.65 to 6.98 kJ.mol−1 with an increase in surface concentration at 303 K and it followed the same pattern for other temperatures. It was found that an increase in temperature enhances the magnitude of the heat of adsorption.

96/06000 Single bed pressure swing adsorption process to generate high purity nitrogen

96/06000 Single bed pressure swing adsorption process to generate high purity nitrogen

Single bed pressure swing adsorption process to generate high purity nitrogen

The separation of air for the production of nitrogen by pressure swing adsorption over a carbon molecular sieve is kinetically based. The basic steps involved in a cycle are typically pressurization, high pressure adsorption, countercurrent blowdown and vent. Simulations studies with DAPS (Dynamic Adsorption Process Simulator) were performed to analyze the effect of the pressurization rate and bed length on the performance of a single bed nitrogen pressure swing adsorption unit in the high purity region. Both specific product and yield improve with the bed length due to the reduction in the axial dispersion effect. A comparison between the predictions of the theoretical model and experimental results was carried out.