@article {49295, title = {Continuous flow synthesis of hierarchical low silica X zeolite}, journal = {Materials Today Communications}, volume = {39}, year = {2024}, month = {JUN}, pages = {109047}, type = {Article}, abstract = {

Zeolites, renowned for their versatile applications in catalysis, adsorption, and ion exchange, have long been synthesized using conventional batch processes. However, the inherent limitations of these methods, such as resource-intensive conditions and inconsistent product quality, underscore the need for a sustainable and efficient approach. In this study, a continuous flow synthesis process was established for the synthesis of industrially important low silica X (LSX) zeolite using a tubular reactor. The synthesis gel was subjected to aging for 5 days at room temperature to facilitate nucleation and crystal growth combined with the fast-heating rate in a tubular reactor at 363 K \& 1.1 atm., which in turn produces LSX after 40 min. The synthesized product was confirmed by the XRD, FE-SEM, EDS, XRF, TEM, and N2 adsorption-desorption; the data was compared with the LSX sample synthesized by batch process. The result implies that LSX prepared by continuous flow has a pure phase of LSX with the hierarchical structure, which provides better adsorption capacity of CO2 at 298 K up to 20 bar. Due to continuous flow synthesis, the crystallization time was reduced and faster kinetics which may be helpful for scale-up the process for LSX synthesis.

}, keywords = {Adsorption, Carbon dioxide, continuous flow, Low silica X, Tubular reactor, zeolites}, doi = {10.1016/j.mtcomm.2024.109047}, author = {Adarsh, V. K. and Shrotri, Aadesh R. and Birje, Amit R. and Nandanwar, Sachin U.} } @article {49022, title = {Performance of Li exchange hierarchical X zeolite for CO2 adsorption and H2 separation}, journal = {Journal of Industrial and Engineering Chemistry }, volume = {133}, year = {2024}, month = {MAY }, pages = {505-514}, type = {Article}, abstract = {

Li exchange hierarchical X zeolite (Li-H-X) was prepared by decationization of X zeolite by NH4Cl solution followed by Li exchange and subsequent calcination. NH4-X and Li-X were prepared to compare the results of LiH-X. XRD, FE-SEM, EDS, N2 adsorption-desorption, and micro-/mesoporous volume were performed. The higher mesoporosity was confirmed in Li-H-X due to the framework dealumination during decationization. Static and dynamic sorption capacity of sorbents was evaluated to identify the performance of sorbent. The CO2 and H2 equilibrium adsorption capacity of Li-H-X was found to be 9.6 mmol g-1 and 0.78 mmol g-1, respectively, at 298 K and 20 bar, which was 25 \% (CO2) and 30 \% (H2) higher than Li-X. Static experimental data were validated using the Langmuir, Freundlich, and Sips models. The CO2 \& H2 dynamic sorption capacity of Li-H-X sorbent for binary gas (CO2/H2, 25/75 \%) was 4.145 mmol g-1 and 0.258 mmol g-1 at 303 K and 10 bar. The higher sorption capacity of Li-H-X was obtained due to large micro-/mesoporous volume of sorbent, which may allow to access unoccupied sites at higher pressure. This result reveals that micro-/mesoporous structure of zeolite adsorbs significantly higher CO2 from binary gas stream, which can use to separate pure H2 from gas stream.

}, keywords = {Adsorption, Carbon dioxide, Hydrogen, Microporous-mesoporous, Separation}, issn = {1226-086X}, doi = {10.1016/j.jiec.2023.12.027}, author = {Shrotri, Aadesh R. and Birje, Amit R. and Niphadkar, Prashant S. and V. Bokade, Vijay and Mali, Nilesh A. and Nandanwar, Sachin U.} } @article {49254, title = {Pressure swing adsorption of Li exchange hierarchical X zeolite for pure hydrogen from binary gas mixture}, journal = {International Journal of Hydrogen Energy}, volume = {73}, year = {2024}, month = {JUL }, pages = {138-147}, type = {Article}, abstract = {

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 highpressure 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.

}, keywords = {adsorbent, Binary gas mixture, Hydrogen purification, Li-H-X, Mesoporous zeolite, Pressure swing adsorption}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.06.011}, author = {Shrotri, Aadesh R. and Birje, Amit R. and Nandanwar, Sachin U.} } @article {49811, title = {Synthesis of Core-Shell ETS-4@LSX zeolite composite to enhance CO2/N2 selectivity in flue gas separation}, journal = {Microporous and Mesoporous Materials}, volume = {399}, year = {2026}, month = {JAN }, pages = {113840}, type = {Article}, abstract = {

The selective removal of CO2 from the flue gas remains a quite challenging due to the weak selectivity of CO2/N2 in adsorbents. Therefore, it is necessary to design an effective sorbent to improve its selectivity. This work attempts to synthesis of novel core-shell ETS-4@LSX composite via a seed-assisted hydrothermal method. In this composite structure, a small pore titanosilcate ETS-4 as a core, while a large pore aluminosilicate LSX forms the outer shell. The effects of ETS-4 seed loading (1-5 wt.\%) and crystallization time on the formation and structural integrity of the core-shell architecture was systematically investigated. The structural and physicochemical properties of samples were characterized by XRD, FE-SEM, HR-TEM, EDS, FT-IR, TGA, N2 adsorption-desorption, and pore size distribution. From XRD pattern and FE-SEM results confirmed that the composite synthesized with 2 wt\% ETS-4 seed and 3 h crystallization time has pure phase of ETS-4@LSX structure. HR-TEM imaging revealed uniform growth of LSX over the ETS-4 surface, resulting in the formation of a continuous shell. The 2 wt\% ETS4@LSX composite demonstrated an outstanding CO2/N2 equilibrium selectivity of 81.4 at 1 bar and 303 K with five and seven times higher than that of pure LSX and ETS-4, respectively. At 20 bar, the composite achieved a CO2 uptake of 5.25 mmol g- 1 and an N2 uptake of 0.50 mmol g- 1. Dynamic adsorption study exhibited the 2 wt\% ETS-4@LSX has 3.52 mmol g- 1 CO2 sorption capacity and N2 uptake capacity of 0.26 mmol g- 1. The enhanced adsorption capacity and selectivity of ETS-4@LSX are attributed to its dual-pore structure, highlighting its potential as an effective adsorbent for CO2 capture from flue gas.

}, keywords = {Adsorption, Core-shell composite, Dual-pore structure, ETS-4, Flue gas, LSX}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2025.113840}, author = {Birje, Amit R. and Shrotri, Aadesh R. and Nandanwar, Sachin U.} }