Abstract
Carbon capture has become a popular issue recently due to global warming. Adsorption of carbon dioxide from the atmosphere is also catching attention from public. However, technique to date still suffers from low gas separation efficiency and regeneration difficulties. Zeolite is natural microporous material that is often used as filter or catalyst. One of the members in the zeolite family called sodium 13X has ability to adsorb carbon dioxide from the atmosphere. Owing to this characteristic, it is chosen as the raw material in this study. Freeze casting method is utilized to synthesize hierarchical micro-sized channel and nano-sized pores through optimized cooling rate and water content. These unidirectional channels allow gas to flow to the interior of the scaffold and enhance adsorption efficiency. Furthermore, binders are necessary in order to provide enough mechanical strength. Bentonite/Poly Vinyl Alcohol are selected as inorganic/organic binder and sintering/etherification process are conducted to elevate compressive strength. The thermogravimetric analysis indicates that the total amount of adsorption is 3 mmol/g and the diffusivity is 10-15~10-16 m2/s. Both results are competitive to the zeolite pellet that is commonly seen. To summarize, hierarchical porous scaffold with unidirectional channels can be successfully synthesized by freeze casting. The total amount of adsorption and diffusivity are both comparable to the zeolite beads that are normally used.