Colloidal Processing and Thermal Treatment of Binderless Hierarchically Porous Zeolite 13X Monoliths for CO2 Capture

Adsorbents with high surface area are potential candidates for efficient postcombustion CO2 capture. Binderless zeolite 13X monoliths with a hierarchical porosity and high CO2 uptake have been produced by slip casting followed by pressureless thermal treatment. The zeolite powder displayed an isoelectric point at pH 4.7 and electrostatically stabilized suspensions could be prepared at alkaline pH. The volume fraction-dependent steady shear viscosity could be fitted to a modified Krieger-Dougherty model with a maximum volume fraction of 0.66. The narrow temperature range where monoliths could be produced without significant loss of the microporous surface area was identified and related to the phase behavior of the 13X material. Slip casting of concentrated suspensions followed by thermal treatment of the powder bodies at a temperature of 800 degrees C without holding time resulted into strong hierarchically porous zeolite 13X monolith that displayed a CO2 uptake larger than 29 wt%.