Tailoring zeolite/polydimethylsiloxane composite production to improve CO2/N2 adsorption selectivity

Abstract Hybrid NaLTA/PDMS composites were produced by dispersing NaLTA zeolite synthesized from calcined kaolin into a polydimethylsiloxane (PDMS) silicone rubber matrix, followed by molding and room-temperature vulcanization to obtain pellet-shaped adsorbents for application in CO 2 /N 2 gas separation. Pellet-shaped composites containing different zeolite loadings were prepared and characterized by XRD, FTIR, and SEM analyses. XRD results confirmed the formation of crystalline NaLTA zeolite and indicated the absence of structural changes after adsorption, suggesting a predominantly physisorption process. FTIR spectra demonstrated the successful incorporation of zeolite into the PDMS matrix, while SEM images revealed homogeneous dispersion and favorable interfacial interaction between the inorganic filler and the polymeric phase. Sorption analyses showed that increasing zeolite loading enhanced CO 2 adsorption capacity, with the composite containing 44 wt% zeolite exhibiting the best overall performance. This material reached a CO 2 /N 2 selectivity of 58.5 at 1000 mmHg, surpassing values reported for similar zeolite/PDMS systems. Cyclic sorption experiments also demonstrated stable adsorption behavior after consecutive CO 2 and N 2 adsorption steps, indicating the potential applicability of the composite in cyclic gas separation processes.