Date of Award

5-2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical and Civil Engineering

First Advisor

Darshan G. Pahinkar

Second Advisor

Hamidreza Najafi

Third Advisor

M. Toufiq Reza

Fourth Advisor

Troy V. Nguyen

Abstract

This work presents the development of a porous, hydrophobic zeolite 13X coating for the separation of carbon dioxide (CO2) from flue gas or natural gas. Zeolite 13X was combined with yeast, glucose, and sodium alginate as pore-forming agents, and with polytetrafluoroethylene (PTFE) and Polydimethylsiloxane (PDMS) as hydrophobicity-inducing agents to enhance water resistance while maintaining CO2 access to the adsorbent. The study explored PTFE/13X mass ratios ranging from 0 to 2.33 to investigate the interplay between hydrophobicity and CO2 uptake. The wettability of the coating was characterized by using a temporal water contact angle (WCA) measurement. Increasing the PTFE fraction enhanced surface hydrophobicity, and for a PTFE/13X mass ratio of 2.00 and a PDMS binder between the coating and the substrates, achieved a WCA of 135°. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses confirmed the effective distribution of both zeolite 13X and PTFE throughout the coating. Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction Spectroscopy (XRD) confirmed that zeolite 13X remains unaffected. Yet, other hydrophilic ingredients have been converted into hydrophobic porous coatings using PTFE and PDMS. The coatings were tested for CO2 uptake after undergoing several water-imbibition and thermal-cycling tests, as well as water-vapor adsorption tests. The coatings with a PTFE/13X ratio of 2.00 on metallic substrates, along with a PDMS binder between the metal and the coating, were considered the best-case scenario from this work, with a WCA of 135°, excellent durability after thermal cycling, CO2 uptake performance within 30% of that of pure 13X, and suppression of water vapor affinity.

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