Author(s)

Masahiro Katoh^1*, Kota Horiuchi², Ayaka Satoh², Kota Aoyagi², Shigeru Sugiyama¹

¹Department of Applied Chemistry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan.
²Department of Chemical Science and Technology, Tokushima University, Tokushima, Japan.

Commercial silicoaluminophosphate molecular sieves (SAPO-34) received alkali treatment with either NaOH (0.2, 0.01, 0.005, or 0.001 M) or NH₄OH (0.005 M). Treatment with NaOH (0.005 M) increased the water adsorption initial rate of SAPO-34 by 1.4-fold. The alkali treatment introduced Na⁺ adsorption sites into the SAPO-34. The desorption ratio (adsorption at 30°C and desorption at 100°C) was 88.2% higher than the original rate (84.3%). On the other hand, after alkali treatment of SAPO-34 using NH₄OH (0.005 M), calcination resulted in the highest desorption ratio at 91.3%. When combined with calcination, alkali treatment with NH₄OH introduced H⁺adsorption sites into SAPO-34, H⁺ adsorption sites feature low levels of interaction with water, which enhanced the desorption ratio, but decreased the initial adsorption rate. These results indicate that treating commercial SAPO-34 with 0.005 M NaOH enhances both the adsorption and desorption behaviors.

Alkali Treatment, Silicoaluminophosphate Molecular Sieves, Water, Adsorption, Desorption

Katoh, M. , Horiuchi, K. , Satoh, A. , Aoyagi, K. and Sugiyama, S. (2019) Alkali Treatment of Commercial Silicoaluminophosphate Molecular Sieves (SAPO_-34) Enhances the Water Adsorption and Desorption Properties. Journal of Encapsulation and Adsorption Sciences, 9, 149-158. doi: 10.4236/jeas.2019.94008.