Selectivity improvement of polysulfone-zeolite templated carbon membrane by annealing and coating treatment for CO2/CH4 and H2/CH4 separation

Natural gas, which majorly consists of methane (CH4), is a renewable
energy source widely used as fuel, as well as hydrogen (H2). However, in
its production process of each gas containing other impurity gasses.
Therefore, membrane technology is needed to separate the gasses from the
impurities. Mixed Matrix Membrane (MMM) is a more promising membrane
compared to the others. Zeolite Templated Carbon-based MMM offers a good
separation performance because of ZTC’s large surface area and
well-defined pore structure. However, the interfacial void in MMM is
challenging to be prevented, which contributes to the reduced separation
performance. This study aims to enhance separation performance by
modifying membrane surfaces using various methods. MMM PSF/ZTC modified by
annealing at 120, 150, and 190 °C; coating using 0.01, 0.03, and 0.05 mol
tetramethylorthosilicate (TMOS); and both combinations annealing at 190 °C
and coating using 0.03 mol TMOS. MMM PSF/ZTC was successfully
significantly improved CO2/CH4 selectivity by both combinations of
annealed at 190 °C and coated 0.03 mol TMOS from 1.37 to 5.90 (331%) and
H2/CH4 selectivity by coating with 0.03 mol TMOS from 4.58 to 65.76
(1378%). The enhancement of selectivity was due to structural changes of
the membrane that was denser and smoother, which SEM and AFM observed. In
this study, annealing and coating treatment are the methods that can use
for improving the polymer matrix and filler particle adhesion.